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Control strategies against voltage collapse considering undesired relay operations
Song, H.,Lee, B.,Ajjarapu, V. IET 2009 IET GENERATION TRANSMISSION AND DISTRIBUTION Vol.3 No.2
<P>Control strategies as countermeasures against voltage collapse considering undesired relay operations are mainly discussed here. In the experiences of blackouts, undesired relay operations have played a very important role in cascading events leading to a voltage collapse. An algorithm for quick identification of critical relays is first depicted, the operations of which may significantly deteriorate the systems in terms of voltage stability. Then, the proposed approach determines a control strategy satisfying a relay margin criterion. For this purpose, a combinatorial optimisation formulation with a utility function evaluated by a quasi-steady-state simulation is used, and a local search algorithm to deal with binary control variables in the formulation is employed. The methodology is demonstrated with the modified New England 39-bus system.</P>
증배형 부하회복 모델을 포함하는 연속법 기반 준정적 해석
송화창(Hwachang Song),Venkatanamana Ajjarapu 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.2
This paper presents a new continuation-based quasi-steady-state(CQSS) time-domain simulation algorithm incorporating a multiplicative aggregated load model for power systems. The authors" previous paper introduced a CQSS algorithm, which has the robust convergent characteristic near the singularity point due to the application of a continuation method. The previous CQSS algorithm implemented the load restoration in power systems using the exponent-based load recovery model that is derived from the additive dynamic load model. However, the reformulated exponent-based model causes the inappropriate variation of short-term load characteristics when switching actions occur, during time-domain simulation. This paper depicts how to incorporate a multiplicative load restoration model, which does not have the problem of deforming short-term load characteristics, into the time simulation algorithm, and shows an illustrative example with a 39-bus test system.
Lee, B,Kang, S.-G,Seo, S,Ajjarapu, V,Song, H IET 2010 IET GENERATION TRANSMISSION AND DISTRIBUTION Vol.4 No.5
<P>A new algorithm for the determination of adequate generation re-dispatch as a protective measure against voltage instability is presented in this study. The study applies the method to the Jeju island system in Korea with a frequency control by the current sourced converter (CSC) high-voltage direct current (HVDC) system, which regulates the local system frequency by the active power injection from the mainland system. In order to transfer the active power using the CSC HVDC system, reactive power consumption is essential, and the frequency control of the HVDC is very fast. Therefore voltage instability may occur if the dynamic reactive support is not enough in the local power system at severe contingencies such as generator's outages. The authors suggest generation against voltage curves (<I>g</I>-<I>V</I> curves), constructed by generation continuation power flow, and propose the procedure to determine voltage stability limit of active power generation at each generator using g-V curves. An illustrative example of the proposed algorithm is shown as applied to the Jeju island system.</P>
Song, Hwachang,Lee, Byongjun,Kwon, Sae-Hyuk,Ajjarapu, V. IEEE 2003 IEEE transactions on power systems Vol.18 No.4
This paper presents a new concept of reactive reserve-based contingency constrained optimal power flow (RCCOPF) for voltage stability enhancement. This concept is based on the fact that increase in reactive reserves is effective for enhancement of voltage stability margins of post-contingent states. In this paper, the proposed algorithm is applied to voltage stability margin of interface flow. Interface flow limit, in the open access environment, can be a main drawback. RCCOPF for enhancement of interface flow margin is composed of two modules, modified continuation power flow (MCPF) and optimal power flow (OPF). These modules are recursively performed until satisfying the required margin of interface flow in the given voltage stability criteria.
Lee, Byongjun,Song, Hwachang,Kwon, Sae-Hyuk,Jang, Gilsoo,Kim, Jun-Hwan,Ajjarapu, V. IEEE 2002 IEEE transactions on power systems Vol.17 No.3
This paper reports a study on determining steady. state voltage stability limit of interface flow on a set of interface lines between the metropolitan region and the neighboring regions in the Korea Electric Power Corporation (KEPCO). The interface flow limit considering severe contingencies is determined with a concept of interface flow margin, which is the active power flow margin of the key transmission lines between one region and others under a fixed load demand condition. The paper proposes a procedure to determine secure limit of active power flow on a set of specified interface lines. The procedure uses the modified continuation power flow (MCPF) tracing a path of power flow solutions with respect to generation shift to vary interface flow. In simulation, voltage stability limits of the metropolitan interface flow of the KEPCO'98 system are determined.