It is getting more difficult to construct new transmission lines, due to the increase of people's demand resulting from the change of social environment and people's consciousness. In order to solve these complicated conditions. we developed a computer system to support the route selecting and surveying of a transmission line. This paper introdouces the methodology for route selecting, designing, surveying of a transmission line and tower designing process using a computer system.

Current transformer (CT) saturation may cause a variety of protective relays to malfunction. The conventional CT is designed that it can carry up to 20 times the rated current. However, the possibility of CT saturation still remains, because the fault current may have substantial amounts of ac and/or de components. This paper presents a iron-cored CT design method to prevent CT saturation. The proposed method employs the overdimensioning factor $(K_{ta})$ considering dc components contained as well as symmetrical ac components in the fault current.

The power demand has increased the groth of industry and improvement of life. Otherwise the power supply is more difficult. because of regional egoism, reinforcement for environment, and investment of money. The load installation should be promoted to rational power management, according to the network, inteligent, and high-function. Therefore, this paper is made a study for the method of energy saving and for energy saving of medium-small type small type-below 500kW medium type-between $500{\sim}1.000kW$.

The second project of the development of distribution automation system was started recently in Korea. We will use two algorithms for feeder automation in this project. The one is Yes/No logic and it will be applied in large city. Yes/No logic determined the faulty section by fault current following information of the fault indicators of each switches. The other is automatic closing process of switches, and it will be applied in rural area. In the latter method, each switches close systematically, and it can find and separate the faulty section, the computer system treats only the feeder reconfiguration finally.

In this study, an adaptive evolutionary computation(AEC), which uses adaptively a genetic algorithm having global searching capability and an evolution strategy having local searching capability with different methodologies, is suggested. This paper develops AEC for solving ELD problem with piecewise quadratic cost function. Numerical results show that the proposed AEC can provide accurate dispatch solutions within reasonable time for the ELD problem with piecewise quadratic cost function.

In this paper, we propose the generalized on-line economic dispatch algorithm including transmission loss. it was derived from the process developing matrix form of the classic ELD problem. it can rapidly calculate generation power using transmission loss and transmission loss sensitivity calculated from the result of power flow analysis. Transmission loss sensitivity ${\partial}P_{loss}/{\partial}P_G$ is derived using optimization technique.

This paper proposes a new short-term load forecasting method for special day, such as Public holidays, consecutive holidays, and days before and after holidays. when the load curves are quite different from those of normal weekdays. In this paper, two Artificial Neural Network(ANN) systems are applied to short-term load forecasting for spacial days in anomalous load conditions.

에너지관리, 제어 시스템(EMS)은 전력계통의 실시간 제어 및 총체적인 관리를 최대화하기 하여 컴퓨터 및 통신 시스템으로 구축된 제어시스템이다. 본 EMS의 주요특성은, 첫째 상당히 빠른 속도로 발전되는 컴퓨터 및 통신 기술들을 수시로 수용할 수 있는 기능, 둘째 상대적으로 지속적이며 오래토록 사용되는 수학적인 알고리즘 및 Buiness Rule들을 처리하는 소프트웨어를 급변하는 Computing 환경에서 적응해 갈 수 있는 기능, 셋째 Heterogenous한 시스템에 접속시킬 수 있는 Database를 갖추었다. 끝으로, 대형 전력계통의 Modeling과 이에 부합하는 실시간 Data로 자동화된 전력계통 실시간 운영상의 결과들을 해석 및 검증하였다.

Daily generation scheduling system (DGSC) is a main tool in the power system operation. In Korea, a DGSC was developed in 1982 and it was updated continuously. However, as new type of generators and the number of constraints are introduced. it is very difficult to use the old DGSC. This paper presents a proposal for the development of new DGSC. In the Proposed proposal, line flow constraint and dispatch of combined cycle plant are included.

F.I(Fault Indicator) is equipped in automatic switchs for Distibution Automation System(DAS), and plays important role of providing the information for picking out a fault section. The restrictive sentence that F.I doesn't react for the inrush current is in the F.I specification. Nevertheless F.I has sometimes mal-functioned on the DAS in Kang-Dong branch office of KEPCO for latest 2 years. This Paper Proved the causes of the mal-function, and proposed the new F.I specification and operation methods against the mal-function causes.

This is Part I of a two part paper dealing with control design in power systems using the method of normal forms. In stressed power systems, due to the presence of increased nonlinearity and the existence of nonlinear modal interactions. there exist some limitation to the use of conventional linear control design techniques. The objective of this work is to understand the effect of the nonlinear modal interaction on control performance and to develop a procedure to design controls incorporating the nonlinear information. Part II presents the numerical results dealing with the design procedure.

This is Part II of a two part paper dealing with control design in petter systems using the method of normal forms. The companion paper (part I) [1] describes the general theory and control procedure. This paper depicts numeral results to show the validation of the proposed method and to observe the effects of controller setting changes.

It is most important in small signal stability analysis of large scale power systems to compute only the dominant eigenvalues selectively with numerical stability and efficiency. Hessenberg process is numerically very stable and identifies the largest eigenvalues in magnitude. Hence, transformed system matrix must be used with the process. Inverse transformation with complex shift provides high selectivity centered on the shift, but does not possess the desired property of computing the dominant mode first. Thus, advantage of high selectivity of the transformation can be fully utilized only when the complex shift is given close to the dominant eigenvalues. In this paper, complex shift is determined by Fourier transforming the results of dynamic simulation with PTI's PSS/E transient simulation program. The convergence in Hessenberg process is accelerated using the iterative scheme. Overall, a numerically stable and very efficient small signal stability program is obtained. The stability and efficiency of the program has been validated against New England 10-machines 39-bus system and KEPCO system.

A fault on the transmission line results in the variation of reactance and parametric uncertainties in the power system dynamics. In this case, we need a robust control to cope with these uncertainties. A sliding mode control, a sort of robust control, is known to be robust to parametric or state-dependent uncertainties if the bounding function of uncertain terms is determined a priori. However, in general, we can not readily determine the bounding function for the complex systems. Hence, in this paper we introduce a fuzzy system which can estimate the bounding function in relatively simple way. By the use of the proposed fuzzy system, determination of bounding function is made easier. We applied the proposed scheme to the stabilization of power system under the sudden fault on the transmission lines. The simulation result verifies the effectiveness of the scheme.

In this paper, sensitivity based approach to estimate BITC(bilateral interchange transfer capacity) considering the real power flow control function of FACTS device is presented. The real power flow setting of the FACTS device is adjusted so that it transfer the power flow from the first violation point of transmission capacity to other transmission lines in the power system, thus allowing more power to be transferred from the specified generator bus to the specified load bus. The transfer between the two bus locations is increased from this new operating condition until a violation of transmission capacity limits occurs or until the setting of the FACTS device can no longer be adjusted. The proposed algorithm is illustrated using examples of small and real life power system.

This paper presents an LQG based robust TCSC supplementary controller design to suppress the SSR in the FACTS. This controller is designed to have the robust stability against the plant model uncertainty. The robust stability is guaranteed using the $\mu$ analysis. Time domain simulations using a nonlinear system model show that the proposed TCSC supplementary controller can suppress the SSR efficiently against the plant model uncertainty.

This paper focuses on the simulation and ciontrol of the Unified Power Flow Controller (UPFC). This paper gives a brief outline of the initial results of the effect of the UPFC on the damping of the power system oscillations. The nonlinear simulation results show the effectiveness of each UPFC control variable and gives the future research direction.

TCSC is a FACTS device that can control the active power flow and current of transmission lines by adjusting line impedances. In this paper, we study the effect of TCSC on power transfer capability. A static model of TCSC is implemented in the continuation power-flow(CPF) Program and the power transfer capability is measured using the CPF. The site of TCSC is selected to increase power transfer capability by the sensitivity information provided from the CPF. The effect of TCSC with various control mode is tested in IEEE New England 30-bus system.

This paper presents the adaptive setting method of distance relay under the single line ground fault. The apparent impedance measured at the relaying point and actual impedance is different because of fault resistance and various prefault loading condition. For a resistance earth fault detection, relay setting zone is adaptively changed with measured load current and bus voltage at the relaying point to avoid maloperation.

Recent development of the digital computer and communication technology has made the concept of the adaptive protection possible, which is to adapt the operating parameters of the protective devices to the system changes, so that the best protection function can be maintained all the time. In order to achieve the adaptive protection, it is necessary to have the way to determine whether the change of the settings is needed under the certain system change or how good the current protection level is. This paper proposed the protectability index, which is a way to evaluate the protection level of the system under arbitary conditions and the operating strategy of the adaptive protection utilizing this index. It is based on an hierachical evaluation model and the evidence combination rule of the Dempster-Shafer theory.

Continuation power flow is a tool that can trace the path of the solution from the base stable solution. However, the base stable solution cannot be calculated when the initial system load is too large to operate at a stable operating point. This case is called as unsolvable case. This paper presents implementation of the optimal load shedding algorithm on continuation power flow. It performs steady-state analysis of power systems at unsolvable case that can occur in contingency analysis. Numerical simulation on 20-bus test system demonstrates that the continuation power flow applying the optimal load shedding algorithm is robust at solvable and unsolvable cases.

When the faults occur in power systems, the protective relay plays a roles of protecting power systems. It is important that the protective relay have high selectiveity and sencitivity performance in power system by correct setting the relays. This paper proposed a testing methods if the reliability of digital relay as simulating the response of relay at faults in the real power system operation environment.

The setting of protective relays, which is critical to the system security, requires a huge volume of data and a lot of repetitive calculations. Since an effective design of a database is essential. The relay setting database must accommodate a variety of protective devices. Also its information can be viewed and updated with easy by humans and by computer programs. This paper describes several existing database designs for power system protection, their advantages and disadvantages. Also this paper develops an effective database for power system protection with their advantages.

Modern AC electric car has PWM(Pulse Width Modulation) -controlled converters, which give rise to higher harmonics. The current harmonics injected from AC electric car is propagated through power feeding circuit. As the feeding circuit is a distributed constant circuit composed of RLC, the capacitance of the feeding circuit and the inductance on the side of power system cause a parallel resonance and a magnification of current harmonics at a specific frequency. The magnified current harmonics usually brings about various problems. That is, the current harmonics makes interference in the adjacent lines of communications and the railway signalling system. Furthermore, in case it flows on the side of power system, not only overheating and vibration at the power capacitors but also wrong operation at the protective devices can occur. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. From these point of view, this study presents an approach to model and to analyse traction power feeding system focused on the amplification of harmonic current. The proposed algorithm is applied to a standard AT(Auto-transformer)-fed test system in which electric car with PWM-controlled converters is running.

This paper presents an algorithm that evaluates the transfer capability of composite power systems using probabilistic approaches. The reliability indices calculated by using probabilistic method are expected maximal flow, expected transfer capability margin, and expected power not supplied. In this paper, a successive linear programming technique is used to evaluate transfer capability named maximal flow. Physical constraints considered in the maximal flow problem are the limits of toad voltage, line overloading, and real & reactive power generation. Numerical results on IEEE RTS show that the proposed algorithm is effective and useful.

Optimal routing of distribution networks can be attained by keeping the line power capacity limit to handle load requirements, acceptable voltage at customer loads, and the reliability indices such as SAIFI, SAIDI, CAIDI, and ASAI limits. This method is composed of optimal loss reduction and optimal reliability cost reduction. The former is solved relating to the conductor resistance of all alternative routes, and the latter is solved relating to the failure rate and duration of each alternative route. The routing considering optimal loss only and both optimal loss and optimal reliability cost are compared in this paper. The results showed that reliability cost should be considered as well as loss reduction to achieve the optimal routing in the distribution networks.

With the development of industry, the qualitical advancement of power is needed. Since it is placed in the end step of power system, the fault at the distribution system causes some users blackout directly. So if the fault occurs, quick restoration is very important subject and, for the reason, induction of the distribution automation system is now being progressed briskly. For the quick restoration of the faulted distribution system, the load shedding of the blackout-area must be followed, and the other problems like the shedded load, faulted voltage and the rest may cause other accident. Accordingly load shedding must be based on the precise calculation technique during the distribution system load flow(dist flow) calculation. In these days because of its superior convergence characteristic the Newton-Raphson method is most widely used. The number of buses in the distribution system amounts to thousands, and if the fault occurs at the distribution system, the speed for the dist flow calculation is to be improved to apply to the On-Line system. However, Newton-Raphson method takes much time relatively because it must calculate the Jacobian matrix and inverse matrix at every iteration, and in the case of huge load, the equation is hard to converge. In this thesis. matrix equation is used to make algebraical expression and then to solve load flow equation and to modify above defects. Then the complex matrix is divided into real part and imaginary part to keep sparcity. As a result time needed for calculation diminished. Application of mentioned algorithm to 302 bus, 700 bus, 1004 bus system led to almost identical result got by Newton-Raphson method and showed constant convergence characteristic. The effect of time reduction showed 88.2%, 86.4%, 85.1% at each case of 302 bus, 700 bus system 86.4%, and 1004 bus system.

Electric arc furnaces (EAFs) are a main cause of voltage flicker due to the interaction of the high demand currents of the load with the supply system impedance. The stochastic models have described the physical phenomena of EAFs. An alternative approach is to include deterministic chaos in the characterization of the arc currents. In this paper, a chaotic approach to such modeling is described and justified. At the same time, a DLL (Dynamic Link Library) module, which is a FORTRAN interface with TACS (Transient Analysis of Control Systems), is developed to implement the chaotic load model in the Electromagnetic Transients Program (EMTP). The details of the module and the results of tests performed on the module to verify the model and to illustrate its capabilities are presented in this paper.

A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

This paper describes the peak load forecasting technique of distribution transformers with correlation equation. While customers are demanding safe energy supply, conventional correlation equation that is used for load management of distribution transformers in domestic has some problems. To get accurate correlation equation, se-correlation equation were examined using new collected using the measuring instrument dev for this study. It was recognized that the qua equation was the most accurate for peak forecasting from working electrical energy.

Electric power distribution feeders are susceptible to faults caused by a variety of situations such as adverse weather conditions, tree contacts, equipment failure, accidents, etc. Distribution circuit faults result in a number of problems related to the reliability of service and customer power quality. In the past, the permanent interruption of customer service resulting from a blown fuse or a recloser lockout was the only factor which was used to determine service reliability. So we developed KODAS(Korea Distribution Automation System) with successful and had fieid-testing of Distribution Automation System in last three years at Kang-dong Branch Office. In performing the project, KEPRI has gained valuable experience, through dealing with many difficult problem. This paper is depicted about the circuit breaker coordination problems in the Underground for the Distribution Automation Feeder.

This paper presents the method of load management to measure the winter season's load characteristics of distribution pole transformers. The proposed load model constructed used by the quadratic load correlation coefficients. To verify the estimated model, we compared with linear model by calculation results. The results can contribute an improvement of conventional load management method.

This paper presents the process on the construction for the remote distribution pole transformer monitoring system. Especially, this system uses CATV cable as communication media which is located in KEPCO's main distribution line. It has four major components such as sensor for measuring secondary voltage and currents of distribution transformer, RF modem for data modulating/de-modulating, communication media for sending/receiving of data, and pc server for monitoring the results of sensing or computing information. This paper also describes the configuration of these each component's configuration and its functions.

This paper presents a method of modeling of DSTATCON (Distribution-line Static Condenser) for installation in a specific plant and analyze the effectiveness of the DSTATCON from the viewpoints of voltage regulation and harmonic mitigation in a distribution line. For the reliable modeling, detailed information on distribution system and loads is performed by field measurements. The DSTATCON has been modeled according to the control algorithm of real controller. The effectiveness of the DSTATCON installation is verified by simulation using EMTDC.

The distance relay is very important for transmission line protection. A quadrilateral zone shape is used mainly for a modern digital distance relay. The shape of quadrilateral is vendor specific. At the stage of design, the shape is determined considering all possible types of faults and diverse configurations of system. Also this type relay must be designed to avoid the operation by a sound phase at single-Phase-to-ground fault, by a sound phase at two-phase-to-ground fault. The effect of a source impedance and a load impedance is another important factor to design. In this paper, a reliable zone shape which is appropriate for the KEPCO's transmission system is provided.

Because of the zero sequence mutual coupling of parallel lines, the distance calculation performed by a distance relay is incorrect. To achieve correct operation, the relay has to use not only the measured quantities of faulty line, but also the zero sequence current of healthy line. But the zero sequence current of the healthy line cannot be always measured. Therefore, we propose the neural network method to estimate the zero sequence current and the criterion to determine whether faulty line or not.

This paper presents an artificial neural network approach to diagnose and detect faults in oil-filled power transformers based on dissolved gas analysis. The proposed algorithm is used to detect faults with or without cellulose involved. Several neural network topologies have been considered. Good diagnosis accuracy is obtained with the proposed approach.

This paper presents an adaptive reclosing scheme to improve the reliability in power distribution systems. For an originated faults, this scheme can determine the number of reclosing attempts, so that minimizes the affect of electric facility and customers' load. To verify the effectiveness of the proposed scheme. numerical simulation which calculates a various indices to consider the reliability and the effect of electric facility, is carried out with actual field data. Results show that the proposed scheme can be applicable to field operation.

This paper presents an application of power system stabilizer for a 5Kw Motor-Generator Set. The power system which was consisted of 5Kw Motor-Generator Set. Excitation system, Governor system and PSS was used for the performance test. The method by changing the PSS gain to allocate properly pole-zero positions was used for setting PSS parameter value. The result of the experiment was satisfactory.

Power telecommunication networks, being used to support the operation and management of power utility services, exhibits different characteristics from those of public domain networks. KEPCO is planning to evolve its own power network infrastructure to exploit ATM (Asynchronous Transfer Mode) technology. The ATM network to be developed needs to effectively utilize existing network of KEPCO and to fully support new and emerging power-utility-services. This paper summarizes the features of power communication services and the characteristics of Power telecommunication networks, and reports our evolution methodology for KEPCO network.

The TC curve of recloser which used in KEPCO's distribution line is a little different in a pattern with the TC curve of sub-station OCR. So it sometimes fails in protection coordination. And the recloser sometimes does mis-open/close owing to the inrush current of CB reclosing when a fault occurred on the source-side of the recloser. The mis-open/close is another trouble maker. This Paper Present a new delay TC curve of recloser which has the same pattern with the TC curve of OCR, and a new instantaneous TC curve of recloser which doesn't mal-function to the inrush current. In addition, this paper present another two TC curves for the serial positioning of 2 reclosers. So we accomplished the simple protection coordination of OCR-recloser-fuse.

In this paper, the proposed controller is obtained by combining the nonlinear feedback linearization-sliding mode controller (NFL-SMC) with the full order observer (FOO) and eliminates the need to measure all the state variables in the conventional NFL-SMC.

In this paper, the standard Dole, Glover, Khargoneker, and Francis (abbr. : DGKF 1989) $H_{\infty}$ controller $(H_{\infty}C)$ is extended to the nonlinear feedback linearization-$H_{\infty}$ /sliding mode controller (NFL-$H_{\infty}$/SMC) to solve the problem associated with the full state feedback for the unmeasurable state variables in the conventional SMC, to obtain the smooth control as the linearized controller for a linear system (or to cancel the nonlinearity for the nonlinear system), and to improve the time-domain performance under worst case.

For a nonlinear feedback linearization-full order observer/sliding mode controller (NFL-FOO/SMC), the separation principle is derived, and the closed-loop stability is proved by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

This paper presents the stability proof of a nonlinear feedback linearization-reduced order observer/sliding mode controller (NFL-ROO/SMC). The closed-loop stability is proved by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

This paper presents a stability proof for the nonlinear feedback linearization-observer/sliding mode model following controller (NFL-O/SMMFC). The separation principle is derived, and the closed-loop stability is proved by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

In this paper, a stability proof of the closed-loop stability for the nonlinear feedback linearization-$H_\infty$/sliding mode controller (NFL-$H_\infty$/SMC) is done by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

This paper presents a stability proof for the nonlinear feedback linearization-full order observer-based sliding mode controller (NFL-FOO-based SMC). The closed-loop stability is proved by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

This paper presents the stability proof of a nonlinear feedback linearization-reduced order observer-based sliding mode controller (NFL-ROO-based SMC). The closed-loop stability is proved by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

This paper presents a stability proof for the nonlinear feedback linearization-observer-based sliding mode model following controller (NFL-O-based SMMFC). The closed-loop stability is proved by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

In this paper, the standard Dole, Glover, Khargoneker, and Francis (abbr. : DGKF 1989) $H_{\infty}$ controller $(H_{\infty}C)$ is extended to the nonlinear feedback linearization-$H_\infty$-based sliding mode controller (NFL-$H_\infty$-based SMC). A stability proof of the closed-loop stability is done by a Lyapunov function candidate using an addition form of the sliding surface vector and the estimation error.

An operationally secure power system is one low probability of blackout or equipment damage. The power system is needed to maintain a designated security level at minimum operating cost. The inclusions of security make power system problem complex. But, because security and optimality are normally conflicting requirement, the separate treatments of both are inappropriate. So, a unified hierarchical formulation is needed. In this paper, the overview of security constrained optimal power flow (SCOPF) is presented and an introduction of parallel distributed formulation to SCOPF is also presented.

We present an approach to parallelizing optimal power flow (OPF) that is suitable for distributed implementation and is applicable to very large interconnected power systems. The objective of this paper is to find a set of control parameters with which the Auxiliary Problem Principle (Algorithm - APP) can be best implemented in solving optimal power flow (OPF) Problems. We employed several IEEE Reliability Test Systems to demonstrate the alternative parameter sets.

We present the implementation of a Lagrangian Relaxation based large scale thermal Unit Commitment problem. The problem is decomposed into thermal subproblem by using Lagrangian multipliers. The thermal subproblem is solved by using dynamic programmmg. we perform a numerical test using the thermal system of KEPCO over a week (168 hours) period. The programming language used for the test program is C. The result is compared with the priority list method.

This paper describes the possible undesier-able side effects that thyristor controlled compensation may have upon in several relays. This process consisted of calculating line conditions for each of the fault, compensation and loading levels. In some cases their effectiveness at coordinating compensated lines is lost, as they no longer can always accurately determine "distances" to faults.

This paper presents a design of network and database structure of the integrated system for power system operational planning and analysis that will be more economical and stable of power system operation. An alias of this system is Highly Integrated Total Energy System(HITES). The Client/server model of HITES is designed as a remote data management model. The input/output-type of application programs and Oracle server is standardized. The separated user-databases from main-database strengthen security of HITES. It is plan to do that tables and relationships are defined by database designs. The connection of application program and DBMS of HITES will be tested through database design and data construction.

This paper presents a database design for power system operational planning system of the integrated system for power system operational planning and analysis that will be more economical and stable of power system operation. An alias of the integrated system is Highly Integrated Total Energy System(HITES). We first describe the requirements for the Power System Planning System of HTES. Database design is processed in two phases(conceptual design and physical design), and CDM(Conceptual Data Model) and PDM(Physical Data Model) are generated by Powerdesigner(CASE tool for database design). In the future, the constructed database needs to be tested and tuning.

This paper presents the evaluation results of Korea Electric Power Corporation (KEPCO) system's power wheeling costs based on the postage stamp method. The results of several postage-stamp-based methodologies are compared where some of them are the conventional approaches. others are new approaches suggested in this paper. The approaches developed in this paper are suitable for a system where transmission transactions are occurred within a vertically integrated power system just like as Korea, Japan. etc. Also, they can overcome limitations related on the depreciation costs application. Test results show that the computed wheeling costs are around 4.0 [won/kWh] in 1995, and it is anticipated that the cost will increase when considering transmission network losses and ancillary costs.

This paper presents a new approach to large-scale optimal generator maintenance scheduling. To do this, we developed a kind of discrete sensitivity index of each generator by using difference of objective fuction when it is on and off status. Based on the sensitivity value, we applied the conventional priority approach as an optimization method in the order of each generator's sensitivity measure. By applying the developed method, we can efficiently search the state space and dramatically reduce the computation time in a large scale power system.

In this paper we present a Neural network approach to select weighting matrices of Linear-Quadratic-Gaussian (LQG) controller for TCSC control. The selection of weighting matrices is usually carried out by trial and error. A weighting matrices of LQG control selected effectively using Neural network. It is shown that simulation results in application of this method to one machine infinite bus system are satisfactory.

The method of building the system state matrix described here is the direct method which constructs elements of state matrix directly by the algebraic expressions from the machine data with time constants. From this method, it is reasonable to confirm the structure of state matrix and the relation of submatrices and elements efficiently. In this paper the interrelationship of submatrices of system matrix is investigated and a constitution of system matrix considering time constants.

In this paper, an efficient feature vector extraction method and MLP neural network are utilized to automatically detect and classify power quality disturbances, where the proposed classification procedure consists of the following three parts: i.e., (i) PQ disturbance detection using discrete wavelet transform. (ii) feature vector extraction from the detected disturbance. using several methods, such as FFT, DWT, Fisher's criterion. etc.. and (iii) classification of the corresponding type of each PQ disturbance by recognizing the pattern of the extracted feature vector. To demonstrate the performance and, applicability of the proposed classification algorithm. some test results obtained by analyzing 10-class PQ disturbances are also provided.

This paper presents a new analytical method for assessing outage cost of composite power system with considering transmission system uncertainty. Composite power system ELDC(CMELDC) was developed and proposed from reliability evaluation of composite power system in order to analysis the outage cost on HLII. In this study, considering the characteristic of each load point, the CMELDC was used for outage cost assessment and reliability evaluation at each load point. The characteristics and effectiveness of this methodology are illustrated by the case study (IEEE-RTS 24Buses).

The while, PD source detection in the oil TR was the level of the planar source detection. and it is to respected scientific research. The planar source detection technique had limits which have difficulties finding out the point of deterioration generation. In this study, our purpose is a development of PD source detection technique with Three-Dimensional using a principle and a technique of the planar source location.

This paper presents a practical fuzzy expert system to diagnose various faults occurred in local power systems. This integrated system can diagnose all faults occurred in a transmission network and substations. In this paper. the fuzzy reasoning of the diagnostic process is discussed in detail. The discrimination of false operations and non-operations of protective devices as well as the fault identification scheme are also analyzed together with the fuzzy inference process.

The main purpose of HITES(Highly Integrate Total Energy System) is to build and develop an integrated energy system for power system operational planning and analysis which consists of load forecast, economic generation schedule, stability analysis and relational database system. The integrated energy system can be utilized to supply a stable electric power and operate KEPCO power system facilities economically. This system will be put into operation in 1999. This paper describes the main feature of the HITES, system main functions, numerical methods adopted this system, and network configuration.

This paper deals with the new fault detection technique for transmission line using Neuro-fuzzy Scheme. Neuro-fuzzy Scheme is ANFIS(Adaptive-network Fuzzy Inference System) based on fusion of fuzzy logic and neural networks. The proposed scheme has five layers. Each layer is the component of fuzzy Inference system and performs different action. Using learning method of neural network, fuzzy premise and consequent parameters is tuned properly.

As the power systems evolve, they are incorporating increasingly complex control and protection functions. Due to this, utilities are relying more and more on real-time simulators to study complex system interaction problems. This paper addresses some key questions regarding the needs of such simulators and their characteristic features/requirements. In countries like France and Canada, large scale simulators are developed and placed in practical use, and in others are now under development. Following this background, three typical simulators(ARENE, RTDS/HYPERSIM) will be examined focusing on the purpose, technology and experiences in a real-time simulator. Discussion will be extended to the future issues and potentials of the power system simulation.

Using EMTP model which describes bipolar HVDC system, switching level simulation results are presented in this paper. Voltage synchronization at point of common coupling, gate pulse generation and current control loops are represented in TACS module. The system consists of 100 km submarine cable rated 300 MW and 12 pulse rectifier and inverter stations which are connected to equivalent three-phase sources and loads through the 154 kV AC lines, respectively. In convertor stations, harmonic filters and capacitor banks are equipped to cancel out the harmonics generated by converters and to supply the required reactive power.

Voltage dips caused by transmission system faults are usually of a short duration. High speed relaying and breaker operation will typically limit the disturbance to 0.1 seconds. Most motor controllers obtain their control power directly from the bus by means of a control transformer. Under this condition, a voltage dip can cause the contactor to drop out. disconnecting the motor from the line. The rapid re-energizing of the controller is in effect a fast reclosure which may result in motor damage. The time delay re-energizing of controller will result in a greater loss of speed and possibly loss of stability. Other means of controller can be used to prevent the motor from being disconnected from line during the fault. This can be accomplished by DC power controller or mechanically latched controller. This paper demonstrates that DC power controller or mechanically latched type controller to prevent the motor from being disconnected from line during the fault is, the most effective in minimizing speed reduction, transient motor current, transient motor torque and transient shaft torque by EMTP calculation.

This paper which can simulate FRIENDS(Flexible Reliable Intelligent Electrical eNergy Delivery System) model of distribution electrical system presents a new algorithm. In the operation of FRIENDS model, dispersed energy storage(DES) systems have an important role. We can use the active and reactive power of DES to control customer's voltage. In this, the former means load levelling operation and the later means voltage control operation of DES. We focus our research on load levelling operation of DES. We develope an algorithm to get an optimal capacity and operation schedule of DES and then apply it to the FRIENDS model. The results show the effectiveness of the proposed method.

This paper discusses the selection of optimal location of Thyristor Controlled Series Compensator (TCSC) devices to maintain the steady-state voltage profile within limits. A procedure for selecting optimal TCSC location based on sensitivity analysis is developed. This approach identifies the critical lines by evaluating all the voltage magnitudes sensitivity with respect to a line reactance. Computer simulation of a example system is used to verify the proposed procedure.

Many other unit commitment performed by complex mathmatical problems and algorithmm. but fuzzy logic is not concerned with mathmatical formulations so unit commitment is scheduled with ease. and fuzzy can express many constraints which has uncertanity feasibly because it use lingustic expressions. In this paper MATLAB is used as a simulation tool. Fuzzy Toolbox is made to make fuzzy control systems. Using this Toolbox easily and effectly we can make good unit commitment.

In this paper, the comparison and analysis of PTI and IEEE data formats are conducted. and the algorithm and the developed program for data conversion between these data formats are proposed. PTI and IEEE data formats are widely used as the input data form of the software program for power systems. However, they are composed of different formation with each other. So, it is necessary to convert between two formats in order to use more programs with different input data format. Numerical results of the power flow calculation of the test system show that developed program is effective and useful.

This paper presents the method of parameter estimation of diffusion model for monitoring Demand-Side Management Program. Bass diffusion model was applied in this paper, which has different values according to parameters ; coefficients of innovation, imitation and potential adopters. Though it is very important to estimate three parameter, there are no empirical results in practice. Thus, this paper presents the method of parameter estimation in case of few data with constraints to reduce the possibility of bad estimation. The constraints are empirical results or expert's decision. Case studies show the diffusion curves of high-efficient lighting and also forecasting of the peak value for power demand considering diffusion of high-efficient lighting, the feedback and least-square parameter estimation method used in this paper enable us to evaluate the status and forecasting of the effect of DSM program.

This paper proposes a new approach for calculating frequency and duration by using the moment matching technique. Two separate expressions are derived, one for the loss of load expectation(LOLE) and the other for the loss of load frequency(LOLF). These expressions are combination of exponentials and are therefore easily integrable and can be readily evaluated. The proposed approach is quite comparable of with the other methods at the aspect of accuracy and efficiency.

This paper describes the dissipation factor measuring device for insulating oil in operating pole transformer by DSP(digital signal processor). After applying voltage to the sensor which is installed in a transformer, acquire source voltage and current of sensor using FFT techniques, then we could evaluate the dissipation factor of insulating oil. To improve measuring accuracy and processing speed, we use TMS320C31 DSP, FFT and data analysis techniques. Also we suggest deterioration criterion of insulating oil and compared the developed diagnosis device with schering bridge on deteriorated insulating oil. The result of this paper show that the developed measuring device can be used as diagnosis device for the pole transformers.

In this paper, we developed a diagnosis device for ZnO arrester to detect on-line leakage current and acquire data from the power distribution system. The arrester is important power equipment used in power transmission and distribution systems to protect the generator and the main transformer from surge and overvoltage. First of all we developed a diagnosis device for ZnO arrester leakage current. And then we detect the total leakage current by the developed device without disconnecting the arrester ground wire and analysis the 3rd order harmonic by Fast Fourier Transform(FFT) to diagnose the ZnO arrester deterioration. With measuring the total current and the resistive current of power distribution system in operation, we analysis the trend of resistive current component in the total leakage current. We expect the result will be promote the method to protect electrical utility and customer from accident.

A distribution systems loss minimum reconfiguration method by simulated annealing is proposed. The problem is a complex mixed integer programming problem and is very difficult to solve by a mathematical programming approach. Simulated annealing generates feasible solutions randomly and moves among these solutions using a strategy leading to a global minimum with high probabilities. The solution algorithm has been implemented in developed software package and tested on 32-bus system.

The cogeneration facilities (COGN) into the power distribution system can cause operational problems - reenergization of distribution feeders under repair by utility personnel, voltage variation and regulation because of output power of COGN, and lost of coordination at emergency state - on an electrical utility system. This paper deals with momentary voltage dips as the parallel interconnection operation of COGN in the power distribution system. PSCAD/EMTDC simulation tool is used to show the behavior of momentary voltage dips. In addition, restraint solution for momentary voltage variation is presented.

The BESS has a major advantages such as load leveling, quick response emergency power (spinning reserve), frequency and voltage control, improvement of reliability, and deferred generation and transmission capacity construction. However, the economic feasibility of these systems requires justification from the customer side of meter. In this paper, we proposed the economic evaluation model of BESS which is modified and complemented the SYSPLAN model[2]. In addition, we analyzed a economic evaluation from the economic measures such as payback period, overall benefit, ROI, and ROR.

An intelligent power transformer protective relaying algorithm based on fuzzy decision-making is proposed. To distinguish external faults with CT saturation, overexcitation and inrush conditions from internal faults, a newly designed fuzzy-rule base is used. The Dempster-Shafer's rule of combition is used for fuzzy inference. A series of the S/W and H/W tests show the proposed protection algorithm has practically sufficient sensitivity and selectivity.

This paper describes methods to quickly reconfigure the branch in a distribution system by using tie-line switches without branch overloading and feeder overloading, voltage in load points, and distribution system is represented by object-based structure to search efficiently.

This paper presents the Two-Phase Neural Network(TPNN) to slove the Optimal Economic Environmental Dispatch problem of thermal generating units in electric power system. The TPNN, Compared with other Neural Networks, is very accurate and it takes smaller computer time for a optimization problem to converge. In this work, in order to provide useful information to the system operator, we are used the total environmental weight and relative weighting of individual insults(e.g., $SO_2$, $NO_X$ and $CO_2$) also, presented the simulation results of the dispatch changes according to the weights. The Two-Phase Neural Network is tested on a 11-unit 3-pollutant system to prove of effectiveness and applicability.

It is becoming more and more difficult to construct new transmission lines because of many social problems. According to the load increase, Some of existing transmission lines will be heavy loaded over the limit. To solve this situation, one of method is peformed by replacing existing ACSR transmission lines with STACIR for increasing power transmission capacity in the 345kv transmission system. This paper presents several techniques for design and construction of transmission line replacement based on the actual experience in the 345kv Shinseongnam-Shinsiheung and Shinseongnam-Shinyeongseo transmission lines.

Voltage Sags, different from electric outages, are important to industrial reliability because modern process controls are often sensitive to voltage sag, the designer and operator should recognize sag characteristics of the electric system not only to protect malfunction of equipment but also to make best choices between reliability and equipment cost. The voltage sags and compensation countermeasures of large md industrial distribution systems have been simulated using EMTDC. The causes of voltage sags occurred in the system are discussed in detail and several countermeasures including the transfer of large induction motor from normal power source to backup source are recommended in order to enhance the ride-through characteristics of equipments.

A robust economic dispatch algorithm involving transmission losses is proposed and investigated for a possibility of on-line applications. In this paper, the penalty factors are calculated directly from transposed Jacobian of load flow analysis with advantages of superiority to B-coefficients method based on its computation time and suitability for real time application since the approach is based on a current system condition. The proposed algorithm is systematically handling the generation capacity constraints with transmission losses. Implementation of the algorithm for IEEE systems and EPRI Scenario systems shows that computation time is enough to apply on-line economic dispatch to large power system and production cost is saved compared with the crude classical economic dispatch algorithm without considering transmission losses.

Recent applications of neural networks to power system fault diagnosis have provided positive results and have shown advantages in process speed over conventional approaches. This paper describes the application of neural network to fault detection and classification in distribution lines using the fundamental component, 2-5th harmonics index, even and odd harmonics index, and zero phase current. The Electromagnetic Transients Program (EMTP) is used to obtain fault patterns for the training and testing of neural networks. The proposed fault detection and classification method in distribution lines is obtained by analysing the difference among normal, HIF, ground fault, short circuit fault condition.

In this study, an adaptive evolutionary computation (AEC), which uses adaptively a genetic algorithm having global searching capability and an evolution strategy having local searching capability with different methodologies, is suggested. We applied the AEC to design of fuzzy logic controllers for a PSS (power system stabilizer). FLCs for PSS controllers are designed for damping the low frequency oscillations caused by disturbances such as tile sudden changes of loads, outages in generators, transmission line faults, etc. The membership functions of FLCs is optimally determined by AEC.

Inchon International Airport(IIA) is constructed for Northeast Asia Gate as is important for IIA to become a 21 century's leader in the world, as is planned for open at december 2000 as a important economic link for unified korea. Airport Power Information System(APIS) is designed through investigation of advanced domestic and international example. In addition to power facility operation it is designed for using an information infrastructure of whole airport. APIS is newly designed for uninterupted power supply, effective power management, information infrastructure's construction. making a profit by positively introduction of new technology for collection and conservation of power related data, correlation with airport infra systems, data interrelative arrangement about related systems like outdoor lighting system and automatic measuring record, CCTV systems for remote power facility monitoring, and promotion of management ability in the emergency status.

Inchon International Airport(IIA) is constructed for Northeast Asia Gate as is important for IIA to become a 21 century's leader in the world. as is planned for open at December 2000 as a important economic link for unified korea. Power System is designed through investigation of advanced domestic and international example. In addition to power facility operation it is designed for using an information infrastructure of whole airport. IIA Power System Design make instantaneously the Power Distribution Facilities and the SCADA System to construct the airport. and the Airport Power Information System to operate the Power System. It is designed to take efficient and safe Power System including the advanced technology. Power System make the integrated Power Information Database to operate the Main Control Center, analyze the data about the relation of the Power System and Airport operation, and will support the important files in the future.

Pilot Scheme은 거리계전방식과 전류차동계전방식의 단점을 보완할 수 있는 방식으로, 자기보호구간에 대해 전 구간을 빠르고 신뢰성있게 보호한다. 본 논문에서는 여러 가지 Pilot Scheme의 특성을 비교 분석하고, Weak Infeed, 전류반전, 통신 에러 등에 대한 효과적인 대책을 갖춘 새로운 Hybrid Scheme을 제안하고, EMTDC에서 얻은 고장데이터를 바탕으로 Digital Logic Simulation을 통하여 Logic을 검증하였다.

Distribution facilities are installed dispersedly nationwide and in view of huge amounts. it makes it difficult to manage and update distribution facilities information manually. Consequently, much efforts have been exerted on computerization of distribution facilities information. KEPCO has been building distribution facilities information system using GIS technology(DGIS) to manage distribution facilities. In order to implement DGIS, digitizing the existing cartographical and land registration map is essential. In this regard, the Government is pursuing the NGIS project. In parrallel with it, DGIS project will be accelerated in the future. This paper suggests the efficient development plans to computerize distribution facilities using GIS technology.

In case of multi-cable for one ph current in the same phase cable may be unba according to cable arrangement in underg system. In this paper, we described the way to ba current in each cable of same phase. This solut to make the impedence of each cable equal caculated the impedence of each cable for all ki cable arrangement in accordance with JCS168D finally found the cable arrangement of impedence.

Effective database is the key to manage automatic distribution system. Currently, automatic distribution system database has been studied with a relational concept. But, it is hard to describe the characteristic of automatic distribution system data which require real time management and composite type. This paper present the way how to design conceptual schema for EMS database using object-oriented concept which is free to decribe composite data type and support inheritance concept.

This paper presents object-oriented dynamic programing formulation of the unit commitment problem. This approach features the classification of generating units into related groups so called class. All object which share the same set of attributes and methods are grouped together in classes and designed inheritance hierarchy to minimize the number of unit combination which must be tested without precluding the optimal path. So this programming techniques will maximize the efficiency of unit commitment.

Static excitation systems with high gain and fast response times greatly aid transient stability. but at the same time tend to reduce small signal stability. The objective of the power system stabilizer(PSS) control is to provide a positive contribution to damping of the generator rotor angle swings, which are in a broad range of frequencies in the power system. Therefore, this paper shows the field test results for the GE's EX2000 PSS tuning on units at Seo-Incheon power plant. The test is to verify that the PSS response meets GE's design, criteria. The responses of generator terminal voltage, active power, field voltage and current were analyzed and PSS gain was tuned by 10 finally.

This paper presents the result of an analysis on effects of phase compensation on power system stability in the PSS parameter tuning. Synchronizing and damping coefficients are induced from lineal model for generator with PSS. Synchronizing and damping coefficients corresponding to time constants of phase compensation control block are calculated on a single machine, infinite bus test system. The Parameter tuning concepts, basic function, structural elements and performance criteria of PSS are introduced.

Recently, our electric industry confronts a structural change and high competiveness environment in the course of deregulation. Rapid growth in electricity demand, financial need for new power plant construction, and envionmental problems have led to search for more efficient energy production and energy conservation techmologies. Especially, residential and commercial buildings consumes 40% of electricity demands and building energies are increasing more and more in Korea. The purpose of this paper is to analyze the electricity use of commercial buildings by end-use. Also, we will use it as a basic informations of DSM potential evaluation and evaluation process based on different approach by sector and type of potential.

Super-conducting Magnetic Energy Storage(SMES) system is considered to be useful unit to power system stabilizer because of high efficiency and quick response. For effective operating of SMES, we need much studies on accurate modeling and interface characteristics of SMES. In this paper, we propose useful method to SMES, modeling using Artificial Neural Network. Interface technique of proposed model and criterion of stabilization effect is presented. In addition, to demonstrate the validity of proposed method. the simulations were carried out on 3-machine 9-bus system.

This paper Presents two distribution-feeder models to simplify complicated distribution system calculations. These equivalent models are developed to simulate the total series voltage drop at the end of the given feeder and the total line loss of the given feeder accurately. In addition, the proposed models are bidirectional. This means that power infeed can be at either end and the model is accurate. Also, it is shown that the proposed models are suitable for network reconfiguration.

The induced voltage of underground pipelines caused by the stray current not only do harm to workers and instruments. but also cause big accident such as gas explosion. The AC stray current is mainly produced by the grounding system of the 22.9kV distribution power system and the DC stray current is mainly produced by the subway system. The mechanism of AC and DC induction, stray current failure examples of domestic and foreign countries and the countermeasure of the AC and DC induction are described.

This paper presents a method of the regional long-term load forecasting considering economic indicator with the assuption that energy demands proportionally increases with the economic indicators. For the accurate load forecasting, it is very important to scrutinize the correlation among the regional electric power demands, economic indicator and other characteristics because load forecasting results may vary depending on many different factors such as electric power demands, gross products, social trend and so on. Three steps are microscopically and macroscopically used for the regional long-term load forecasting in order to increase the accuracy and practically of the results.

The Load characteristic of electric railway requires the power demand of the high capacity which amplitude is spacial-temporally fluctuated due to frequent starting and stopping with large tractive force. The conventional electric railway mainly consists of the resistance controlled and the thyristor controlled locomotives, are compensated for their bad characteristics of the power factor$(70\sim80%)$ with installation of another capacitor improving power factor at the substation. Since 1994, VVVF train car with good characteristics of power factor(100%) have been introduced and operated in Kwa-Chon Line. From the present technical tendency, it is judged that introduction of the locomotive with various controlled methods is necessary. The protective equipments installed at the substation are complicated and various aspects to detect faults and reduce their extension, so the universal countermeasures are required. Specially in the case of the fault occurrence it is difficult to calculate the fault location because of the change in the contactline constant according to modifying the characteristics of the contactline (the dualized catenary wire and extension, etc), so much time is required for the detection of fault location. In BT-fed method distance-relays and fault-locators are not installed, we have so many difficulties in the quick accident recovery.

The electrical power of nuclear power plant consists of Safety related power systems and Non-Safety related power systems. The safety related power systems are designed to have sufficient capacity to safely shut down the unit and to mitigate the effects of an accident assuming loss of off-site power. This paper presents the operation scheme of the safety related power system for several plant conditions in Korean Next Generation Reactor and reviews the diversity of power supply to the safety related bus.

This paper presented the development plan of voltage security on-line monitoring system (VSECOMs). VSECOMs consists of voltage security monitoring system and data management system. VSECOMs has the function of bus voltage watch. voltage stability analysis, and voltage security assessment. EMS data on-line acquisition, PSS/E file conversion, and overall data management. VSECOMs is designed with client/server structure. We will seek stable operation of KEPCO's power system by installation of VSECOMs in EMS of KEPCO.

This paper presents a model reduction procedure of the high order MIMO (multi input multi output) controller designed for the steam turbine in the generating plant. The application limit to reduction of the order is reviewed by variation in Hankel singular value as well as by variation in singular value Bode diagrams of transfer function matrices. Dynamic performances in the time domain are also compared for each reduced order model.

This paper describes the induced voltage of sheath on 154kV transmission power cable in multi fault states. Simulation was carried out to obtain the induced voltage of sheath according to change of, fault angle and grounding resistance using EMTP. Modeling of cable system is also established in EMTP to analyze. The simulation results can be useful reference to design cable system in power system.

Recently high impedance fault(HIF), which includes arcing wave, has often occured in power system. Some papers related to arcing phenomena and its modeling have been published. However the proposed methods show much different form in compare with actual arc wave under HIF. It is not so available to use to analyze HIF because of such problem. This paper proposes the new arcing wave model, which is nearly similar to actual arcing wave, developed using PSCAD/EMTDC. The arcing waves obtained from arcing model that applied in actual. power system are compared with some actual arcing wave gained from the field test and show the availability to application of relay test.

The object of this study shows a program for supervisory control of the electric power distribution, approach to the more easy manipulations and hangulization that could be easily familiar to the domestic operators whereas the program, up to now, displayed only in English. This program is consist of a skeleton-diagram designer and a state-displayer of the electric power distribution To make skeleton-diagram data available in state-displayer, the designer must be performed with the proposed format in the program manual. States display executes downloading S/Ws-state-data externally and display the S/W informations at that times, and also power distribution simulation of voluntary S/W manipulations performed by the internal operators is possible.

Detailed estimation of subsurface resistivity distribution and accurate estimation of actual fault current coming into the grounding system are indispensible to optimun grounding system design. Especially, it is essential for efficient grounding design to estimate subsurface resistivity distribution quantitatively and logically. Accurate estimation of subsurface resistivity distribution has an absolute influence on calculating touch voltage, step voltage and ground potential rise (GPR) which are related with grounding design standard for human safety. In this study, thirty-three electrical sounding surveys were made in Yongdam Power Station to obtain detailed subsurface resistivity distribution and the sounding data were interpreted quantitatively using multi-layered model. The results of the quantitative resistivity models were adopted practically to calculate grounding resistance values. Analytical asymptotic equations and CDEGS program were used in grounding resistance calculation and the results were compared and reviewed in the study.

This paper presents a optimal operation algorithm of 1MW class Battery Energy Storage System (BESS) which is constructed in EHWA electric corporation. Total electric charge of conventional '97 year and simulated '98 year are compared to verify the validity of the proposed algorithm. Simulation results have showed that the about \\32,000,000 reduction of electric charge for 1 year.

In this paper a design method of robust power system stabilizers is proposed by means of robust linear quadratic regulator design technique under power system's operating condition change, which is caused by inner structure uncertainties and disturbances into a power system. It is assumed that the uncertainties present in the system are modeled as one equivalent signal. In this connections an optimal LQR control input for disturbance rejection, the output feedback gain for eliminating the disturbance are calculated. In this case. PSS input signal is obtained on the basis of weighted ${\Delta}P_e$ and $\Delta\omega$. In order to stabilize the overall control of system. Pole placement algorithm is applied in addition. making the poles of the closed loop system to move into a stable region in the complex plane. Some simulations have been conducted to verify the feasibility of the proposed control method on a machine to infinite bus power system. From the simulation results validation of the proposed method could be achieved by comparisons with the conventional PSS with phase lag-lead compensation.

전력 사업자들은 일반 수용가에 대한 공급 신뢰도를 개선하기 위해서 배전 자동화 시스템을 도입, 실시간 고장구간 탐색 및 계통 재구성을 추진하고 있다. 그러나. 고장 감지기 자체의 오동작이나 통신상의 오류, 다중사고의 가능성 등 불확실성을 포함하고 있기 때문에 비상시 사고구간 추정에 많은 노력과 시간비용이 요구될 수 있다. 따라서. 본 연구에서는 확률론과 휴리스틱 탐색법을 이용하여 배전자동화 시스템에 수집된 정보가 불확실성을 포함하는 경우에도 신속하게 사고 예비 후보 지역을 제시함으로써 고장구간 추정시간을 최소화 할 수 있는 전문가 시스템이 개발된다.

Fault Detection of power system must be rapid and precise over input signal without relation to any disturbance. But, it is difficult to detect current unbalance, over voltage, and underfrequency for digital relay comparison of fault perfectly. In this paper, we measure each phase current and infer type of fault using fuzzy pattern classification.

For 21th Century, the assignment of power distribution will be the expansion of equipments to supply electric power and harmony with its environment, in process of approving value consciousness of land, space, and the preservation of surroundings. This paper proposes a plan to match with the requirement about equipments, having ability to supply electric power, being harmonized itself with its surroundings by applying a general concept of "Amenity" when we choose an established form of power distribution.

The complexity of newly developed protection algorithm and higher performance requested by the user makes the software embedded in the protective relay much harder to develop and maintain. The versatility of 32bit microprocessor and the availability of cheaper memory semiconductors introduced the fertile developing background for the protective relay developers. The use of component object model(COM) in the software developing process enables the developer to write much complex code in the easy and safe way and to maintain the code easily, too. And the aid of the COM library, the distributed computing environment will be expected to appear by the use of the COM programming model in the protective relay firmware program.

This paper presents the result of a feasibility study for the prediction method of fault symptoms on 22.9kV distribution line. In this paper, real distribution data was collected and analyzed to isolate failure signatures or parameters which were distinct behaviors before and after failure incident. A new strategy of analysis-based (event-date concept) prediction algorithm for the distribution insulators and a developed model system were also discussed.

For the improvement of an adaptive SPAR(Single-Phase Auto-Reclosure) and novel protection schemes, it is important to simulate arc faults. But, it is difficult to reproduce the real arc behaviour, i.e. the extinction phenomenon exactly by computer simulations due to extremely random behavior of secondary arc. This paper proposes a new computer modeling techniques for the primary and the secondary arc separately, which can be implemented with EMTP MODELS routine, and the performance of the proposed model is simulated on a typical 154 [kV] korean transmission line system.

High Power Laboratory is the facility for building to simulate the various phenomena generated from electric systems of the real world and to test making and breaking capability, switching capability and durability of circuit breaker, switchgear and other electric utilities, moreover, load equipments which contain capacitor bank is installed for studying the diverse effects originated from the constituent of load through entire systems or receiving end. Such factors, abnormal voltage or current, can be serious in electrical systems, especially, in the case caused by capacitive components such as overvoltage or inrushcurrent, the problems may be more fatal to the systems. In this paper, the optimal design of capacitor bank which will be equipped in High Power Laboratory, which is for simulating as closely as the practical phenomena resulted from the capacitive currents, and the verification aided by computer simulations are presented. For this, analysis of the circuit characteristics according to the standards which can be criteria of the capacitive current tests and the test circuit configuration in accordance with the analysis are proposed in prelude. In the body of the paper the optimal design of capacitor bank has been obtained on the basis of all conditions mentioned above and the test circuit configuration with LGIS test requirements. furthermore, analysis and verification for the design are derived by EMTP. finally, evaluation for the capacitor bank design and further study plan are concluded.

This paper presents an effect of cross magnetization to the generator characteristics in synchronous machine infinite bus system. Eigenvalues, synchronous torque and damping torque are investigated as the operating condition of the system is changed variously. The simulation results show that cross magnetization has an important effect to the generator characteristics in steady state stability analysis.

The deadbeat control has many advantage such as the ouput response without a ripple and the fast settling time. This paper presents a deadbeat control system to damp out the sustained low frequency oscillation. The proposed deadbeat control system consists of th integral controller and the state observer, and it is simulated on the one-machine infinite-bus model of a power system. The efficiency of the proposed control system is verified through the several case studies.

Design & Operation of power system for meeting increase of electric power demand is becoming more difficult and complex. One of reasons is increase of fault current. As one of the most effective methods for suppressing the fault current, installation of SFCL is expected. This paper describes a method of fault analyses of power system with SFCLs, and also discusses determination of specification of SFCLs, effects of limiting the fault current due to SFCLs by use of the model system of two - bus electric power system with parallel circuit model transmission line. Also, describes the definition of six specific parameters of SFCL for power system application & a proposal of design method of specific parameter of a resistance type SFCL in overhead transmission lines considering operation of protective relays.

Spacer Dampers must be carefully designed and tested. Because it can protect conductors from conductor oscillations due to winds and electrical forces. If the spacer damper has any problems in itself, it may cause extensive damage to the transmission lines. This paper suggests a design method and considerations of spacer damper for bundled conductor transmission lines.

For economic operating of distribution system, utility has to minimize the loss in distribution line by controlling reactive power and power factor. This paper presents calculation of reactive power in distribution line, estimation of the condenser capacity according to distance, and computation of optimal location and proper condenser capacity.

This paper presents a basic interposing module system to control nuclear power plant. In this paper, the system consists of master and loop controller. Also that we developed communication module and control logic software.

This paper present a variety fault problem brought out with the multifunctional Battery Energy Storage System [MBESS] expected to be practical in the short future interconnected to power distribution system. Multifunctional BESS model and interconnection model to power system is simply configured, the problems of protection coordination and operation is studied. A line fault in the power distribution system are discussed such as line to ground and three phase fault in order to show the impact on power utilities, demand-side and BESS-side. In order to simulate a variable transient phenomenon due to 2 the BESS interconnection operation to power distribution system, in this paper, PSCAD/EMTDC simulation tools is used.