• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.107-114
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• 2021

High penetration of renewable energy generators causes unnecessary investment for power system facilities. Especially with Korean government policies such as Renewable Energy 3020 and Inter-connection support Responsibility of KEPCO for 1 MW DERs, the applications of DER interconnection in distribution system have been increasing. To save the investment, smart control functions for DERs are required and the test bed for the inverters which have not been prepared are necessary to insure DER inter-connection stability. For this, test bed for advanced functions of a smart inverter has been constructed and the tests for necessary functions have been implemented. In this paper, the test bed and environment as well as specifications are introduced and the test results for the validation of the functions are analyzed.

• 전기학회논문지
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• 제67권10호
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• pp.1382-1387
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• 2018

There is a high demand for energy efficiency improvement of factories that make up a large part of national electric energy. Therefore, research on smart FEMS technology for monitoring, analyzing and controlling energy consumption patterns is under way, but there is still a lack of research on detailed element technology for communication and control inside the factory. In this paper, we proposed OFDM VLC system based on MODBUS protocol for communication between gateways, sensors, and devices to implement smart FEMS in indoor factory environment. Assuming a conveyor belt load control, we validated the proposed system by simulating the inverter motor control and checking the performance.

• International Journal of Computer Science & Network Security
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• 제22권4호
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• pp.1-12
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• 2022

In order to overcome the power fluctuation issues in photovoltaic (PV) smart grid-connected systems and the inverter nonlinearity model problem, an adaptive backstepping command-filter and a double second order generalized Integrators (DSOGI) controller are designed in order to tune the AC current and the DC-link voltage from the DC side. Firstly, we propose to present the filter mathematical model throughout the PV system, at that juncture the backstepping control law is applied in order to control it, Moreover the command filter is bounded to the controller aiming to exclude the backstepping controller differential increase. Additionally, The adaptive law uses Lyapunov stability criterion. Its task is to estimate the uncertain parameters in the smart grid-connected inverter. A DSOGI is added to stabilize the grid currents and eliminate undesirable harmonics meanwhile feeding maximum power generated from PV to the point of common coupling (PCC). Then, guaranteeing a dynamic effective response even under very unbalanced loads and/or intermittent climate changes. Finally, the simulation results will be established using MATLAB/SIMULINK proving that the presented approach can control surely the smart grid-connected system.

• 전기전자학회논문지
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• 제26권1호
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• pp.1-9
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• 2022

전력시스템의 신뢰성을 보장하며 분산전원의 수용성을 높이기 위해 IEEE 1547과 같은 표준을 개정하여 분산전원의 계통 연계기준을 강화하고 있다. 본 논문은 이러한 표준을 준수하는 IEEE 1547-2018 기반의 스마트 인버터 기능의 제어 알고리즘을 제안하고, 스마트 인버터 기술의 검증을 위해 구축한 Power HILS 기반의 테스트 플랫폼을 소개한다. 스마트 인버터 기능 중 Volt-var 제어와 Frequency-watt 제어 알고리즘은 상호운용성 표준을 준수하도록 해당 기능의 curve를 상위로부터 설정할 수 있도록 하며, 각 기능의 Enable 신호 시점을 상위 지령에 따라 제어할 수 있도록 하였다. 표준에 따라 Power HILS 테스트 플랫폼을 통해 Volt-var 제어와 Frequency-watt 제어에 대한 형식시험을 수행하였고, 명시된 표준 형식시험을 전부 만족함을 측정 결과를 통해 검증하였다.

• IEIE Transactions on Smart Processing and Computing
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• 제5권1호
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• pp.35-42
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• 2016

Developments in power electronics have enabled the widespread application of Pulse Width Modulation (PWM) inverters, notably for connecting renewable systems to the grid. This study demonstrates that a high-quality power can be achieved using a stand-alone inverter, whereby the comparison between the power quality of the stand-alone inverter with battery storage (off-grid) and the power quality of the utility network is presented. Multi-loop control techniques for a single phase stand-alone inverter are used. A capacitor current control is used to give active damping and enhance the transient and steady state inverter performance. A capacitor current control is cheaper than the inductor current control, where a small current sensing resistor is used. The output voltage control is used to improve the system performance and also control the output voltage. The inner control loop uses a proportional gain current controller and the outer loop is implemented using internal model control proportional-integral-derivative to ensure stability. The optimal controls are achieved by using the Sisotool tool in MATLAB/Simulink. The outcome of the control scheme of the numerical model of the stand-alone inverter has a smooth and good dynamic performance, but also a strong robustness to load variations. The numerical model of the stand-alone inverter and its power quality are presented, and the power quality is shown to meet the IEEE 519-2014. Furthermore, the power quality of the off-grid system is measured experimentally and compared with the grid power, showing power quality of off-grid system to be better than that of the utility network.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.319-324
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• 2005

The interface between host processor and the ShortStack Micro Server may be a Serial Communication Interface(SCI). The LonWorks control module with a high performance is developed, which is composed of the 8 bit PIC Microprocessor for host processor and the smart neuron chip for the ShoretStack Micro Server. This intelligent control board is verified as proceeding the various function tests from experimental system with an boost pump and inverter driving systems. It is also confirmed that the developed control module provides stably 0-10VDC linear signal to the input signal of inverter driving system for varying the induction motor speed. Thus, the experimental results show that the fabricating intelligent board carried out very well the various functions in the wide operating ranges of boost pump system. This developed control module expect to apply to industrial fields to require the comparatively exact control and monitoring such as multi-motor driving system with inverter, variable air volume system and the boost pump water supply systems.

• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.101-105
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• 2021

Encouragement of DER from Korean government with several policies boosts DER installation in power system. When the penetration of DER in the grid is getting high, loss of generation with break-away of DER by abnormal grid conditions should be considered, because loss of high generation causes abnormal low frequency and additional operations of protection system. Therefore, KEPCO where is Korean power utility is preparing improvement in regulations for DERs connected to the grid to support abnormal grid conditions such as low and high frequencies or voltages. This is called 'Ride Through' because the requirement is for DER to maintain grid connection during required periods when abnormal grid conditions occur. However, it is not easy to have a test for ride through capability in reality because emulation of abnormal grid conditions is not possible in real power system in operation. Also, it is not easy to have a study on grid effect when ride through capability fails with the same reason. PHILs (Power Hardware In the Loop System) makes it possible to analyze power system and hardware performance at once. Therefore, this paper introduces PHILs test methods and presents verification of ride through capability especially for low voltage grid conditions.

• Journal of Power Electronics
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• 제15권5호
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• pp.1338-1347
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• 2015

DC injection is a critical issue in transformerless grid-connected inverters. DC injection control based on virtual capacitor has the advantages of low cost, low loss, high accuracy and easy implementation. In this paper, the principle of DC injection control based on virtual capacitor was analyzed. In addition, the applicable conditions, working process, steady state error and advantages were also discussed in detail. The design of the control parameters based on virtual capacitor was proposed in a grid-connected inverter with LCL filter. The robustness of the control parameters was also discussed. Simulation and experimental results verify the validity of the analysis and demonstrate that this research has a certain value in engineering applications.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.414-420
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• 2005

The ShortStack Micro Server enables any product that contains a microcontroller or microprocessor to quickly and inexpensively become a networked, Internet-accessible device. The ShortStack Micro Server provides a simple way to add LonWorks networking to new or existing smart devices. . It implements the LonTalk protocol and provides the physical interface with the LonWorks communication. The ShortStack host processor can be an 8, 16, or 32-bit microprocessor or microcontrollers. The ShortStack API and driver typically require about 4kbytes of program memory on the host processor and less than 200 bytes of RAM. The interface between host processor and the ShortStack Micro Server may be a Serial Communication Interface (SCI). The LonWorks control module with a high performance is developed, which is composed of the 8 bit PIC Microprocessor for host processor and the smart neuron chip for the ShortStack Micro Server. This intelligent control board is verified as proceeding the various function tests from experimental system with an boost pump and inverter driving systems. It is also confirmed that the developed control module provides stably 0-10VDC linear signal to the input signal of inverter driving system for varying the induction motor speed. Thus, the experimental results show that the fabricating intelligent board carried out very well the various functions in the wide operating ranges of boost pump system. This developed control module expect to apply to industrial fields to require the comparatively exact control and monitoring such as multi-motor driving system with inverter, variable air volume system and the boost pump water supply systems.

• 한국전기전자재료학회논문지
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• 제32권4호
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• pp.327-332
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• 2019

Recently, inverter control systems have attracted immense attention to increase the energy efficiency. However, such systems use repeated on/off high currents for linear operation control, instead of the prevalent step variable current control method. Hence, there arise concerns of personal and property damage, especially due to the durability, explosive characteristics, and operating speed of the fuse, which is responsible for safety and is one of the internal components using current control. Therefore, in this paper, we propose an IEC60127-4 SMD sub-miniature fuse, consisting of Ag-Cu alloys and ceramic powder for arc soothing. The IEC60127-4 SMD sub-miniature fuse has high durability and cut-off capacity, and operates safely in dangerous circumstances caused by the inverter control system.