• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.3 no.1
• /
• pp.223-228
• /
• 1999

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Vu Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system, It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.425-433
• /
• 1999

This paper describes a simulation model and a scaled hardware model to analyze the dynamic performance of Unified Power Flow Controller, which can flexibly adjust the active and reactive power flow through the ac transmission line. The design of control system was developed using vector control method. The results of simulation and scaled hardware test show that the developed control system works accurately. And both models are very effective to analyze the dynamic performance of the Unified Power Flow Controller.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.423-424
• /
• 2015

전압 안정도를 향상 시키고 무효전력을 보상하는 방법 중 하나로 정지형 무효전력보상설비(SVC, Static Var Compensator)를 사용한다. 특히, 전기로(EAF, Electric Arc Furnace) 등 비선형 부하가 주를 이루는 철강 민수 사업자의 부하는 단시간 내에 전류 변화가 급격히 일어나며 큰 전압 변동을 일으키므로 무효전력 보상설비를 적용하여 안정적인 전력을 공급하고 전력 품질을 확보해야 할 필요가 있다. 본 논문에서는 LS-Nikko 동제련 온산 공장에 역률 보상을 목적으로 무효전력을 제어하기 위한 ${\pm}100[MVar]$ SVC 시스템 모델을 소개하고, 그 특성에 대한 이해를 돕고자 한다.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.60-62
• /
• 2005

The operation and control scheme of reactive power compensator (so called STATCOM) based on voltage source converter is theoretically reviewed. STATCOM for compensation of load power factor is designed and its operation is verified by simulation.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.8
• /
• pp.401-409
• /
• 2005

This paper describes a feasibility analysis result of STATCOM application for the Jeju-Haenam HVDC system. The Jeju-Haenam HVDC system is one of the typical HVDC system interconnected with the low short-circuit-ratio AC system, which is vulnerable to the commutation failure due to the AC voltage variation. STATCOM has been considered as an effective reactive-power compensator to increase short-circuit-ratio of the interconnected AC system. In this study, a simulation model of Jeju-Hacnam HVDC system with STATCOM was developed using PSCAD/EMTDC. The developed simulation model was utilized to analyze the dynamic performance analysis of Jeju-Haenam HVDC system with STATCOM. The analysis results show that STATCOM can improve the dynamic performance of Jeju-Haenam HVDC system, such as load-change recovery performance and fault recovery performance.

• Journal of Power Electronics
• /
• v.10 no.5
• /
• pp.572-578
• /
• 2010

This paper discusses a transformerless shunt static compensator (STATCOM) based on a modular multilevel converter (MMC). It introduces a new time-discrete appropriate current control algorithm and a phase-shifted carrier modulation strategy for fast compensation of the reactive power and harmonics, and also for the balancing of the three-phase source side currents. Analytical formulas are derived to demonstrate the accurate mechanism of the stored energy balancing inside the MMC. Various simulated waveforms verify that the MMC based STATCOM is capable of reactive power compensation, harmonic cancellation, and simultaneous load balancing, while controlling and balancing all of the DC mean voltages even during the transient states.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.198-200
• /
• 2004

The purpose of this paper is to explain improvement of voltage stability using STATCOM by active power margin and reactive power margin. STATCOM, the representative shunt compensator of the FACTS devices, is faster than machinery compensator in response speed and has the advantage of the small scale because it doesn't use reactor or large capacitor. In this paper, we investigated the compensatory effect of the STATCOM that applied to KEPCO system.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.4_1
• /
• pp.377-385
• /
• 2021

High voltage direct current(HVDC) systems has been an alternative method of a power transmission to replace high voltage alternate current(HVAC), which is a traditional AC transmission method. Due to technical limitations, Line commutate converter HVDC(LCC-HVDC) was mainly used. However, result from many structural problems of LCC-HVDC, the voltage source converter HVDC(VSC-HVDC) are studied and applied recently. In this paper, after analyzing the reactive power and output voltage ripple, which are the main problems of LCC-HVDC, the characteristics of each HVDC are summarized. Based on this result, a new LCC-HVDC structure is proposed by combining LCC-HVDC with the MMC structure, which is a representative VSC-HVDC topology. The proposed structure generates lower reactive power than the conventional method, and greatly reduces the 12th harmonic, a major component of output voltage ripple. In addition, it can be easily applied to the already installed LCC-HVDC. When the proposed method is applied, the control of the reactive power compensator becomes unnecessary, and there is an advantage that the cut-off frequency of the output DC filter can be designed smaller. The validity of the proposed LCC-HVDC is verified through simulation and experiments.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.146-147
• /
• 2014

This paper presents an operation of the modular multilevel converter-high voltage direct current (MMC-HVDC) system as a Statcom to support the grid voltage. The advantage of the MMC-HVDC system is that it can control the active and reactive powers independently. The proposed control scheme will be designed by combining this performance and the control method of the Statcom. The grid voltage is regulated by the control of the reactive power, meanwhile the active power is controlled according to its applications. The simulation results based on the PSCAD/EMTDC simulation program will evaluate the effectiveness of the control scheme.

• Proceedings of the KIPE Conference
• /
• 2019.07a
• /
• pp.35-37
• /
• 2019

본 논문은 배전선로 안정화 구현을 위한 무효전력 보상기의 새로운 무효전력 제어기법을 제안하였으며, 시뮬레이션 및 실험을 통해 무효전력제어 알고리즘의 성능을 검증하였다. 무효전력 제어는 동기좌표계 d축 전류성분 제어를 통해 수행되고, DC 링크 전압을 일정하게 유지하기 위한 전압 제어와 이에 필요한 유효전력은 q축 전류성분 제어를 통해 구현된다. 제안된 무효전력 제어기법에 포함된 DC 리플 보상방식은 추출된 DC 전압의 오프셋 성분을 제거하는 HPF(high pass filter)부와 HPF 위상 특성으로 인해 발생한 위상변화 특성을 보상하기 위한 지연함수부로 구성되며, 리플성분이 보상된 전압을 전압제어기 피드백 성분으로 적용하였다. 시뮬레이션 및 실험을 통해 DC 전압 리플 보상방식이 적용된 무효전력 제어 기법이 적용된 경우 전류 THD가 크게 향상된 결과로부터 제안된 알고리즘의 성능을 검증하였다.