• 제목/요약/키워드: UPQC-Q

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A New Control Scheme for Unified Power Quality Compensator-Q with Minimum Power Injection

  • Lee, Woo-Cheol
    • Journal of Power Electronics
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    • 제7권1호
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    • pp.72-80
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    • 2007
  • Voltage sags are one of the most frequently occurring power quality problems challenging power systems today. The Unified Power Quality Conditioner (UPQC) is one of the major custom power solutions that are capable of mitigating the effect of supply voltage sags at the load or Point of Common Coupling (PCC). A UPQC-Q employs a control method in which the series compensator injects a voltage that leads the supply current by $90^{\circ}C$ so that the series compensator at steady state consumes no active power. However, the UPQC-Q has the disadvantage that its series compensator needs to be overrated. Thus it cannot offer effective compensation. This paper proposes a new control scheme for the UPQC-Q that offers minimum power injection. The proposed minimum power injection method takes into consideration the limits on the rated voltage capacity of the series compensator and its control scheme. The validity of the proposed control scheme is investigated through simulation and experimental results.

통합 전력품질 제어기의 과전류 보호방법에 관한 연구 (A Study on Over Current Protection Method of Unified Power Quality Conditioners)

  • 이우철;김한정
    • 조명전기설비학회논문지
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    • 제16권5호
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    • pp.22-28
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    • 2002
  • 본 논문에서는 직렬형, 병렬형 능동전력필터로 구성되어 있는 통합전력품질 제어기(UPQC)의 과전류에 대한 보호기법이 제시되며, 해석된다. 제안된 과전류 보호기법은 직렬형 능동전력필터에 과전류의 기본파 성분에 대해서고 임피던스를 갖는 기능을 부여함으로써 구현하였으며, 세 가지 방법을 제시하였다. 첫 번째 방법은 p-q이론을 이용하여 기본파 전원전류를 검출하여 보호하는 방법, 두 번째 방법은 동기 좌표계에서 부하전류의 기본파 성분을 검출하여 보호하는 방법, 세 번째 방법은 입력전압을 검출하여 보호하는 방법이다. 전원계통에서 과전류가 흘렀을 경우 제안된 방법들은 UPQC에 부가적인 회로 없이 보호해 줄 수 있다. 제안된 방법의 타당성은 시뮬레이션 결과를 통하여 입증된다.

통합 전력품질 제어기의 과전류 보호방법에 관한 연구 (A Study on Over Current Protection Method of Unified Power Quality Conditioners)

  • 채범석;이우철;이택기;현동석
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2001년도 전력전자학술대회 논문집
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    • pp.543-547
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    • 2001
  • A protection scheme for Unified Power Quality Conditioner (UPQC) is presented and analyzed in this paper. The proposed UPQC has the series active power filter operated as a high impedance k($\Omega$) to the fundamentals when short-circuit faults occur in the power distribution system, and three control strategies are proposed in this paper. The first is the method by detecting the fundamental source current through the p-q theory, the second is the method by detecting the fundamental component of load current in Synchronous Reference Frame(SRF) and the third is the method by detecting the input voltage. When the short-circuit fault occur in the power distribution system, the proposed scheme protects the UPQC without additional protection circuits. The validity of proposed protection scheme is investigated through simulation results.

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Over Current Protection Schemes for Active Filters with Series Compensators

  • Lee, Woo-Cheol;Lee, Taeck-Kie
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • 제4B권3호
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    • pp.134-145
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    • 2004
  • This paper presents and analyses protection schemes for a series active compensator, which consists of a Unified Power Quality Conditioner (UPQC) or a hybrid active power filter. The proposed series active compensator operates as a high impedance "k(D)" for the fundamental components of the power frequency during over current conditions in the distribution system. Two control strategies are proposed in this paper. The first strategy detects the fundamental source current using the p-q theory. The second strategy detects the fundamental component of the load current in the Synchronous Reference Frame (SRF). When over currents occur in the power distribution system momentarily, the proposed schemes protect the series active compensator without the need for additional protection circuits, and achieves excellent transient response. The validity of the proposed protection schemes is investigated through simulation and compared with experimental results using a hybrid active power filter systems.