• 전력전자학회논문지
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• 제10권6호
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• pp.626-633
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• 2005

본 논문에서는 직렬인버터를 이용한 2MVA SSFG(Sag Swell Flicker Generator)를 제안하였으며, 제안된 SSFG는 직렬인버터, DC 커패시터, 정류기, 클램프회로 등으로 구성되어 있다. SSFG는 선로에 순간전압강하/상승(sag/swell), 과전압/저전압(over/under voltage), 플리커(Flicker)등과 같은 전형적인 외란을 발생할 수 있을 뿐만 아니라, 인버터의 제어를 통해 상 뒤틀림(phase jump)도 구현 가능하다. 본 논문에서 제안된 2MVA SSFG의 효과적인 제어를 위해 세 가지 형태의 제어방식을 PSIM 시뮬레이션을 통해 비교${\cdot}$검토하였으며, 이 중 가장 효과적인 제어방식을 2MVA SSFG에 적용하여 순간전압강하, 순간전압상승, 플리커 등과 같은 외란발생 시험을 수행하였다.

• 전기학회논문지
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• 제58권6호
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• pp.1138-1145
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• 2009

This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The output power of a wind power system changes irregularly according to the variation of wind speed. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The operational feasibility of the proposed model was verified by simulations with PSCAD/EMTDC and the feasibility of hardware implementation was confirmed by experimental works with a scaled hardware model. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.

• 제어로봇시스템학회논문지
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• 제15권12호
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• pp.1163-1168
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• 2009

The power quality of wind energy becomes more and more important in connecting wind-farms to the grid, especially weak grid. This paper presents the simulation of a wind farm of a permanent magnet synchronous generator (PMSG) and a doubly fed induction generator (DFIG). Flicker mitigation is performed by using PMSG as a static synchronous compensator (STATCOM) to regulate the voltage at the point of common coupling (PCC). A benefit of the measure is that integrating two function of to control the active power flow and to reduce the voltage flicker in a wind farm. Simulation results show that controlling PMSG is an effective and economic measure in reducing the flicker during continuous operation of grid connected wind turbines regardless of short circuit capacity ratio, turbulence intensity and grid impedance angle.

• Journal of Power Electronics
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• 제3권3호
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• pp.185-196
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• 2003

In this paper, the single-phase static VAR compensator (SVC) is applied to regulate and stabilize the generated terminal voltage of the single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) under the conditions of the independent inductive load variations and the prime mover speed changes The conventional fixed gain PI controller-based feedback control scheme is employed to adjust the equivalent capacitance of the single-phase SVC composed of the fixed excitation capacitor FC in parallel with the thyristor switched capacitor TSC and the thyristor controlled reactor TCR The feedback closed-loop terminal voltage responses in the single-phase SEIG coupled by a VSPM with different inductive passive load disturbances using the single-phase SVC with the PI controller are considered and discussed herem. A VSPM coupled the single-phase SEIG prototype setup is established. Its experimental results are illustrated as compared with its simulation ones and give good agreements with the digital simulation results for the single-phase SEIG driven by a VSPM, which is based on the SVC voltage regulation feedback control scheme.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1346-1354
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• 2018

Quality of the power system depends upon the reliability of its components such as transformer, transmission lines, insulators, circuit breakers and isolators. The transient voltage due to internal or external reasons may affect the insulation level of the components. The insulation level of these components must be tested against these conditions. Different studies, testing of different electrical components against high voltage impulses and different industrial applications rely on the international manufactures for pulsed power generation and testing, that is quite expensive and large in size. In this paper a model of impulse voltage generator with capacitive load of pin type insulator is studied by simulation method and by an experimental setup. A ten stage high voltage impulse generator (HVIG) is designed and implemented for different applications. In this proposed model, the cost has been reduced by using small and cheap capacitors as an alternative for large and expensive ones while achieving the same effectiveness. Effect of the distributed capacitance in each stage is analyzed to prove the effectiveness of the model. Different values of front and tail resistances have been used to get IEC standard waveforms. Results reveal the effectiveness at reduced cost of the proposed model.

• 전기학회논문지
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• 제63권4호
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• pp.476-483
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• 2014

This paper describes the operational analysis results of the bipolar DC distribution system coupled with the distributed generators. The energy management for AC/DC power trade and the operational principle of distributed generators and energy storages were first analyzed by computer simulation with PSCAD/EMTDC software. After then a hardware simulator for the bipolar DC distribution system was built, which is composed of the grid-tied three-level inverter, battery storage, super-capacitor storage, and the voltage balancer. Various experiments with the hardware simulator were carried out to verify the operation of bipolar DC distribution system. The developed simulator has an upper-level controller which operates in connection with the controllers for each distributed generator and the battery energy storage based on CAN communication. The developed hardware simulator are possible to use in designing the bipolar DC distribution system and analyzing its performance experimentally.

• 전기학회논문지
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• 제63권2호
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• pp.224-229
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• 2014

This paper presents the novel voltage control method in power distribution system with distributed generators. The voltage in distribution systems is regulated by Under Load Tap Changer(ULTC) of substation and pole transformer of primary feeders. Recently, Step Voltage Regulator(SVR) is getting located at distribution feeders to regulate effectively voltage of primary feeders. But the effectiveness of SVR decreases due to independent operation between SVR and ULTC, and also the existing Line Drop Compensator(LDC) method considering the distributed generators may be not able to regulate the proper voltage in a permissible range. Thus, this paper presents a optimal voltage control algorithm of SVR by using the secondary voltage data of main transformer in substation.

• Journal of Power Electronics
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• 제10권6호
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• pp.762-768
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• 2010

This paper describes the development of a new islanding detection method for inverter-based distributed generation systems, which uses a signal cross-correlation scheme between the injected reactive current and the power frequency deviation. The proposed method injects 1% of the reactive current to the rated current which brings about a negligible degradation of the power quality. It discriminates the islanding state, when the calculated cross-correlation index is larger than 0.5. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software and experimental research with a hardware prototype. The proposed method can detect the islanding state without degrading the power quality at the point of common connection. Further study is required to overcome the cancellation of the injected reactive current from multiple distributed generation units interconnected with the utility grid.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1045_1046
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• 2009

This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.

• 대한전자공학회논문지
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• 제27권6호
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• pp.963-971
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• 1990

This paper proposes a memory intensive VLSI architecture for the realization of real-time 3x3 neighborhood processor based on the distributed arithmetic. The proposed architecture is characterized by a bit serial and multi-kernel parallel processing which exploits the pixel kernel parallelism and concurrency. The chip implements 8 neighborhood processing elements in parallel with efficirnt input and output modules which operate concurrently. Besides the a4chitectural design of a neighborhood processor, the design methodology using module generator concept has been considered and MOGOT(MOdule Generator Oriented VLSI design Tool) has been constructed based on the workstation. Based on these design environments MOGOT, it has been shown that the main part of the suggested architecture can be designed efficiently using 2\ulcorner double metal CMOS technology. It includes design of input delay and data conversion module, look-up table for inner product operation, carry save accumulator, output data converter and delay module, and control module.