• Title/Summary/Keyword: Reactive power compensation

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The Characteristics of the STATCOM System operated by SVPWM (SVPWM 방식의 STATCOM 시스템 동작 특성)

  • Lee, Hwa-Su;Kim, Yong-Heon;Lee, Eun-Woong;Lee, Dong-Ju
    • Proceedings of the KIEE Conference
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    • 2003.10b
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    • pp.69-71
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    • 2003
  • STATCOM which is connected the load parallel with capacitor, is the reactive power compensation device. In this paper, we study the principle of reactive power compensation with STATCOM system. And then we confirmed the function of STATCOM system to be fabricated by our lab, being measured and analyzed the output voltage and current

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Coordination of UPFC and Reactive Power Sources for Steady-state Voltage Control (정상상태 전압제어를 위한 UPFC와 조상설비의 협조)

  • Park, Ji-Ho;Lee, Sang-Duk;Jyung, Tae-Young;Jeong, Ki-Seok;Baek, Young-Sik;Seo, Gyu-Seok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.5
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    • pp.921-928
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    • 2011
  • This paper presents a new method of local voltage control to achieve coordinative control among UPFC(Unified Power Flow Controller) and conventional reactive compensation equipments, such as switched-shunt and ULTC(Under-Load Tap Changing) transformer. Reactive power control has various difficult aspects to control because of difficulty of system analysis. Recently, the progress of power electronics technologies has lead to commercial availability of several FACTS(Flexible AC Transmission System) devices. The UPFC(Unified Power Flow Controller) simultaneously allows the independent control of active and reactive power flows as well as control of the voltage profile. When conventional reactive power sources and UPFC are used to control system voltage, the UPFC reacts to the voltage deviation faster than the conventional reactive power sources. Keeping reactive power reserve in an UPFC during steady-state operation is always needed to provide reactive power requirements during emergencies. Therefore, coordination control among UPFC and conventional reactive power sources is needed. This paper describe the method to keep or control the voltage of power system of local area and to manege reactive power reserve using PSS/E with Python. The result of simulation shows that the proposed method can control the local bus voltage within the given voltage limit and manege reactive power reserve.

Reactive Power Control Algorithm of Grid-Connected Inverter at the Point of Common Coupling With Compensation of Series and Parallel Impedances (직병렬 임피던스 보상을 통한 계통 연계 분산전원 인버터의 PCC 무효전력 제어 알고리즘)

  • Heo, Cheol-Young;Song, Seung-Ho;Kim, Yong-Rae
    • The Transactions of the Korean Institute of Power Electronics
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    • v.27 no.2
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    • pp.92-99
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    • 2022
  • Due to space and geographical constraints, the power source may be located outside the island area, resulting in the considerable length of transmission line. In these cases, when an active power is transmitted, unexpected reactive power is generated at a point of common coupling (PCC). Unlike the power transmitted from the power generation source, the reactive power adversely affects the system. This study proposes a new algorithm that controls reactive power at PCC. Causes of reactive power errors are separated into parallel and series components, which allows the algorithm to compensate the reactive current of the inverter output and control reactive power at the PCC through calculations from the impedance, voltage, and current. The proposed algorithm has economic advantages by controlling the reactive power with the inverter of the power source itself, and can flexibly control power against voltage and output variations. Through the simulation, the algorithm was verified by implementing a power source of 3 [kVA] capacity connected to the low voltage system and of 5 [MVA] capacity connected to the extra-high voltage system. Furthermore, a power source of 3 [kVA] capacity inverter is configured and connected to a mock grid, then confirmed through experiments.

Unbalanced Power Sharing for Islanded Droop-Controlled Microgrids

  • Jia, Yaoqin;Li, Daoyang;Chen, Zhen
    • Journal of Power Electronics
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    • v.19 no.1
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    • pp.234-243
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    • 2019
  • Studying the control strategy of a microgrid under the load unbalanced state helps to improve the stability of the system. The magnitude of the power fluctuation, which occurs between the power supply and the load, is generated in a microgrid under the load unbalanced state is called negative sequence reactive power $Q^-$. Traditional power distribution methods such as P-f, Q-E droop control can only distribute power with positive sequence current information. However, they have no effect on $Q^-$ with negative sequence current information. In this paper, a stationary-frame control method for power sharing and voltage unbalance compensation in islanded microgrids is proposed. This method is based on the proper output impedance control of distributed generation unit (DG unit) interface converters. The control system of a DG unit mainly consists of an active-power-frequency and reactive-power-voltage droop controller, an output impedance controller, and voltage and current controllers. The proposed method allows for the sharing of imbalance current among the DG unit and it can compensate voltage unbalance at the same time. The design approach of the control system is discussed in detail. Simulation and experimental results are presented. These results demonstrate that the proposed method is effective in the compensation of voltage unbalance and the power distribution.

The Generalized Instantaneous Power Theory Using Mapping Matrices (맵핑 매트릭스를 사용한 일반화 순시전력 이론)

  • Kim, Hyo-Sung;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • 1997.07f
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    • pp.1930-1932
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    • 1997
  • Instantaneous active/reactive powers are defined in three phase four wire systems. The definition can be generally applicable to any source conditions and load conditions including nonlinear circuits. The zero-sequence power resulted from the zero-sequence voltage and zero-sequence current between two sub-systems affects both to the instantaneous active and reactive powers. The zero-sequence current can be controlled by compensation of the reactive power without power storage elements.

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Harmonic and Reactive power compensation of standby power supply(SPS) using digital controller (디지탈 제어기에 의한 예비전원장치 (SPS)에서의 고조파 및 무효전력보상)

  • Park, Ga-Woo;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.498-501
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    • 1994
  • This paper presents a digital calculation method of instantaneous reactive power component for standby power supply(SPS) system. Reactive current is defined in time domain, calculated instantaneously by using a TMS320C25. The theoretical analysis is verified by the digital simulation and experimental results.

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A Study on the Compensation of Reactive Power by III, IV Quadrant Phase Controlled Rectifier (III, IV상한 위상제어정류기에 의한 무효전력 보상에 관한 연구)

  • 정연택;서영수;이사영
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.32 no.3
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    • pp.76-83
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    • 1983
  • This paper describes the method of operating the phase controlled rectifier by controlling the firing angle in III, IV quadrant to absorb the lrading reactive power and of improving the waveform of ac current by driving dual converter. The system is intended to compensate the reactive power for any lagging load. Also, by the above method this paper enables us to improve the power factor and waveform referred to the source current and the dc output voltage in the converter.

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Analysis of the Distribution STATCOM for Improving the power factor and Mitigation of Voltage Flicker in Real System (전압플리커 저감과 역률 보상 기능을 갖는 배전용 STATCOM의 실계통연계 운전결과 분석)

  • Oh, Kwan-Il;Jeon, Young-Soo;Park, Sang-Tae;Choo, Jin-Boo
    • Proceedings of the KIEE Conference
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    • 2000.07a
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    • pp.245-248
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    • 2000
  • This paper presents the test and operation results of the domestic demonstration of the reactive power compensation device called STATCOM (STATic COMpensator). The object of the paper is to describe the reliability of the unit based on the extensive operation databases. By controlling reactive power, the technology offers utilities the opportunity for increased efficiency and their capabilities will permit transmission planners make the best use of their existing transmission resources STATCOM is a custom power device in a way and can be used in a similar way for the dynamic compensation of power transmission systems, mitigation of voltage flicker and improving the power factor. It is shown that the STATCOM has clear advantages in areas such as: mitigation of voltage flicker and improving power factor.

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Coordinated Control of SVC and ULTC Considering Reactive Power Compensation Margin (무효전력 보상여유를 고려한 SVC와 ULTC의 협조제어)

  • Moon, Kyeong-Seob;Son, Kwang-Myoung;Lee, Tae-Gi;Lee, Song-Keun;Park, Jong-Keun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.4
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    • pp.351-357
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    • 1999
  • This paper proposes the coordinated control of SVC and UTLC at the distribution substation to get larger operating margin of SVC for the voltage stability control by reactive power compensation. In the conventional method, ULTC doesn't respond to the variation of source voltage, so SVC has the entire responsibility for it. It could cause the lack of operating margin of SVC in some condition. It, however, is important to secure an operating margin for the dynamic stability control in emergancy. This paper proposes the coordinated control method that SVC controls the supply voltage and ULTC respond to the SVC compensation valve based on the relation between SVC compensation and ULTC tap position. The numerical simulation verifies that the proposed system could increase the operating margin of SVC compared with the conventional system.

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A Study on the Improvement for Power Quality Problems Caused by Electrical Arc Furnace in Power Systems (전력계통에서 전기로 부하에 대한 전력품질 개선방안에 관한 연구)

  • Kim, Jae-Eon;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.3
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    • pp.444-453
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    • 2007
  • This paper deals with a powerful countermeasure for power quality problems caused by the operation of electrical arc furnace in bulk power systems. The rapid active load fluctuations of electrical arc furnace could produce several problems such as voltage flicker and active power oscillations. The typical methods using only the reactive power compensation have their own limitation in solving the power quality problems caused by active load variations. The coordination of both active and reactive power compensation is required to solve the power quality problems. This paper focuses on the impacts and the dynamic phenomena caused by the active load fluctuation. This paper proposes the optimal algorithm for the active power compensation based on the function of 1(n ratio and the concepts for the active power compensation. The results from a case study show that the proposed methods can be a practical tool for the power quality problems in power systems.

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