• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.655-657
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• 1996

The objective of this paper is to compare the series and shunt approaches of controlled reactive power compensation to improve power system transient stabilities. Including main circuit considerations of series and shunt compensators, application aspects are thought to have major impacts on efficiency and economy of the installation of the compensators. The concept is studied by means of EMTP simulations on one machine-Infinite Bus Test System which consists of a 612MVA steam turbin generator and transformer and double circuit 345KV transmission line. Idealized dynamic models of Thyristor Controlled Series Compensation and Shunt Compensation are used for the comparative study of the series and shunt compensation approach to damp power system oscillations.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.11
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• pp.133-140
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• 1982

In recent years, a number of thyristor-controlled shunt compensators have been used in industrial and utility systems for phase balancing, power-factor correction and flicker reduction. This paper describes a simple and basic control scheme and circuits for shunt compensator with a fixed capacitor and thyristor-controlled reactor. Feedforward-control scheme is applied, and compensating currents are computed from the symmetrical components of the disturbed system. A 8 bit microprocessor is used for the computation of the compensating currents as well as for the measurements of the symmetric components. A 3-phase 1 KVA compensator is developed and a good reduction of the unbalance factor of the power source is achieved using it.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.689-697
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• 2012

This paper proposes a new coordinated voltage control scheme between STATCOM (Static Synchronous Compensator) and reactive power compensation devices, such as shunt elements(shunt capacitor and shunt reactor) and ULTC(Under-Load Tap Changer) transformer in a local substation. If STATCOM and reactive power compensators are cooperatively used with well designed control algorithm, the target of the voltage control can be achieved in a suddenly changed power system. Also, keeping reactive power reserve in a STATCOM during steady-state operation is always needed to provide reactive power requirements during emergencies. This paper describes the coordinative voltage control method to keep or control the voltage of power system in an allowable range of steady-state and securing method of momentary reactive power reserve using PSS/E with Python. In the proposed method of this paper, the voltage reference of STATCOM is adjusted to keep the voltage of the most sensitive bus to the change of loads and other reactive power compensators also are settled to supply the reactive power shortage in out range of STATCOM to cope with the change of loads. As the result of simulation, it is possible to keep the load bus voltage in limited range and secure the momentary reactive power reserve in spite of broad load range condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.1-8
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• 2010

The ultrafashionable machinery that require high quality electricity power has been daily come into being. Because domestic power system has been larger and more complicated in accordance with raising power demand by power market requirement. Because of these power market situations, The FACTS (Flexible AC Transmission System) which is power transmission system for the next generation to meet flexible supply the power and reliability has been applied. If they, compensators and FACTS, are used inter-efficiently in range that does not affect the stability and a badly influence the security, they might be increase in the voltage stability of system, supply reliability and also achieve the voltage control in a suddenly changed power system. Therefore we describe and suggest on this treatise that a plan for coordination control between UPFC, Shunt elements (Sh. Capacitors & Sh. Reactors) among compensators and also describe the method to keep or control the voltage of power system in allowable ranges. The method follows that, we used characteristics of each equipment, UPFC would be also settled to keep the identified voltage range in change of load bus, Shunt elements also would be settled to supply the reactive power shortage in out of operating range of UPFC to cope actively with change of the power system. As the result of simulation, it is possible to keep the load bus voltage in limited range in spite of broad load range condition. This helps greatly for the improvements of supply reliability and voltage stability.

• Proceedings of the KIEE Conference
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• summer
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• pp.224-226
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• 2004

Flexible AC Transmission System (FACTS) can greatly reinforce power systems through improvement of power transmission capacity and utilization of equipment under the circumstance of continuous load growth and deregulation SVC and STATCOM are shunt FACT devices that have similar static characteristics with Mwhuical Swikhed Capacitor (MSC). The main issue of this paper is the analysis of different dynamic characteristics when STATCOM is solely adopted and when STATCOM is adopted with combination of other reactive power compensator such as SVC and M5C. Furthermore, better application of reactive power compensators can be clarified through analysis of dynamic characteristics of various combinations of reactive power compensators.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2737-2743
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• 2015

The wind power plant must be able to produce reactive power at the POI bus of a wind farm connected to power system to keep or control the voltage of POI bus. But, the reactive power capability of wind turbines may not be sufficient to control the voltage of POI bus due to the reactive power losses in connection lines between wind farm and POI bus. The solution of this problem is to install an external STATCOM. The proposed cooperative control method of STATCOM and conventional reactive power compensators such as Switched-shunt and tap changing transformer can control the voltage of POI bus more efficiently. The simulation results are shown that the voltage drop of POI Bus of Test System with the arbitrary load change rate to initial loads is improved more than 60% and the voltage of load bus is maintained more than 95% of rated voltage.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.269-271
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• 2006

In power system, the reactive power is closely associated with voltage. In addition Reactive power has localized characteristic. Recently wide area blackout caused by reactive power imbalance. Therefore it is important to control reactive power considering its characteristic. Until now maintenance of system voltage has been controlled by shunt compensation rather than generators. However because of a large time-constant, shunt compensators are difficult to manage disturbances immediately. In addition shunt compensation has discrete characteristic, which make disturbances in system. In this paper we studied the voltage maintenance method of local buses by controlling the reactive power output of a generator which is closely related a load bus in addition the proposed method was verified by test system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1011-1016
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• 2010

It is an important issue to electric power system operations that it can reliably supply large-capacity power to consumption area as due to increasing power demand growth. For this purpose, The FACTS equipment based on Power IT technology with the existing mechanical compensators has been applied to power system. Therefore we suggest on this paper that a plan for coordination control of multiple power compensation equipment in order to increase the utilization of each facility and secure operation margin capacity. As the result of simulation, it is possible to cope actively with a suddenly changed power system. This helps greatly for the voltage stability and supply reliability in a suddenly changed power system.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.8-17
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• 2015

This paper analyses the power flow of a three-feeder/multi-bus distribution system by a custom Generalized Power Quality Conditioner (GUPQC). The GUPQC has been realized by three voltage source converters (VSCs) coupled back-to-back through a common DC-link capacitor on the DC-side. One feeder was controlled by the shunt compensator, whereas each of the other two feeders was controlled by the proposed novel series compensator. The GUPQC has the capability to simultaneously compensate voltage and current quality problems of a multi-bus/three-feeder distribution system. Besides that, the power can be transferred from one feeder to other feeders to compensate for poor power quality problems. Extensive simulation studies were carried out by using MATLAB/SIMULINK software to establish the ability of the GUPQC to improve power quality of the distribution systems under distorted supply voltage conditions.

• Journal of Power Electronics
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• v.6 no.3
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• pp.195-204
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• 2006

This paper presents a new compensating system, consisting of series and shunt active filters, for mitigating voltage and current disturbances. The shunt filter is used to compensate for unbalanced and distorted load currents. The series filter comprises two inverters, used to suppress voltage disturbances and handle source currents independently. This configuration is devised to reduce the overall cost of active compensators by using low-frequency high-current switches for the latter inverter. The filters are controlled separately using a novel control strategy. Since voltages at the point of common coupling contain interharmonics, conventional methods cannot be used for extracting voltage references. Therefore, voltage references are obtained from generated sinusoidal waveforms by a phase-locked loop. Current references are detected based on rotating frame vector mapping. Simulation results are presented to verify the system.