• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.19-23
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• 2003

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 art recursively perform ed until satisfying the required margin of interface flow in the given voltage stability criteria.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.158-161
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• 2004

This paper presents practical applications of reactive power and voltage planning to obtain voltage stability and operational voltage level for 2005 year summer peak Korea power system. It also describes the new electric facilities, operation criteria, voltage levels, MVAr flows, reactive power reserves in each control area. And reactive compensation devices are installed to maintain established voltage levels and stability margins. This simulation results show the improvement of voltage levels and the increase of reactive margins & interface flow margins. Finally, the paper reports the necessity of dynamic reactive reserves. It can be applied to analysis reactive compensation requirements and P-V & V-Q curves by PSS/E & VSAT.

• 대한전기학회논문지:전력기술부문A
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• 제54권6호
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• pp.274-283
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• 2005

This paper presents a new method to derive energy function based on vector product. Using this method, an energy function to consider transfer conductances and capacitors is derived. Then we recommend a voltage collapse criteria to predict the voltage collapse in power systems by using the energy margin derived by the proposed energy function. This energy function is applied to a 2-bus power system reflecting transfer conductances and capacitors. We show that the energy function derived based on vector product can be applied in order to analyze power system stability and the energy margin can be utilized as a criterion of voltage collapse by simulation for the 2-bus system.

• 대한전기학회논문지:전력기술부문A
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• 제54권7호
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• pp.337-344
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• 2005

An energy function is derived on the basis of the EMM(Equivalent Mechanical Model) to take account of the effects of tap changer, and then the VC(Voltage Collapse) criteria is proposed to predict the voltage collapse in Power systems. The VC criterion can be evaluated by using the energy margin given by the energy gap between UEP(Unstable Equilibrium Point) and SEP(Stable Equilibrium Point) of the energy function adopted, in which it is noted that the energy contour should be considered due to energy discontinuity associated with tap changing. This paper shows that the proposed VC criterion improves the accuracy of voltage stability analysis with application to a two-bus sample system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1143-1146
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• 1998

Static excitation systems with high gain and fast response times greatly aid transient stability. but at the same time tend to reduce small signal stability. The objective of the power system stabilizer(PSS) control is to provide a positive contribution to damping of the generator rotor angle swings, which are in a broad range of frequencies in the power system. Therefore, this paper shows the field test results for the GE's EX2000 PSS tuning on units at Seo-Incheon power plant. The test is to verify that the PSS response meets GE's design, criteria. The responses of generator terminal voltage, active power, field voltage and current were analyzed and PSS gain was tuned by 10 finally.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.335-336
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• 2015

Voltage collapse is one of the main threats in power system operation and it is a result of a very low voltage profile in one or multiple areas in the power system network. Hence, the need for proper coordination among transmission and generator operators to maintain voltage stability if of paramount importance. In this paper, the different voltage and reactive power operating guidelines and criteria of various electric reliability councils, coordinating councils, transmission system operators and other electric utilities are discussed. Among these are NERC, ENTSO-E, WECC, PJM and ERCOT. A comprehensive comparison is also made to the existing Korean power system voltage reliability guidelines. Furthermore, this paper presents a set of voltage and reactive power guidelines that can help in determining voltage limits that can improve the reliability of the Korean power system operation.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.337-345
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• 2009

Deregulation in power industry has made the reactive power ancillary service management a critical task to power system operators from both technical and economic perspectives. Reactive power management in power systems is a complex combinatorial optimization problem involving nonlinear functions with multiple local minima and nonlinear constraints. This paper proposes a practical market-based reactive power ancillary service management scheme to tackle the challenge. In this paper a new model for voltage security and reactive power management is presented. The proposed model minimizes reactive support cost as an economic aspect and insures the voltage security as a technical constraint. For modeling validation study, two optimization algorithm, a genetic algorithm (GA) and particle swarm optimization (PSO) method are used to solve the problem of optimum allocation of reactive power in power systems under open market environment and the results are compared. As a case study, the IEEE-30 bus power system is used. Results show that the algorithm is well competent for optimal allocation of reactive power under practical constraints and price based conditions.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.491-492
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• 2016

This paper presents a robust feedback control design to mitigate the effect of grid voltage disturbances for three-phase grid-connected inverters in distributed generation systems. The proposed strategy consists of two major design steps. First, the controller is synthesized using the internal model principle to achieve a good reference tracking and disturbance rejection performance. Then, the feedback gain is systematically obtained by solving the linear matrix inequality conditions which are directly derived from the stability criteria. The main contribution of this paper is that the complexity of control structure can be substantially reduced and transient response is improved as compared with the existing robust control design methods. The simulation results are given to prove the validity of the proposed control scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.567-568
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• 2015

신재생에너지와 같은 분산전원의 연게와 전력계통 네트워크 구성방식의 고도화에 따른 기존의 네트워크 해석방식과의 차별성을 가지는 토폴로지 탐색방법을 제안한다. 배전계통 ICT 인프라는 이러한 응용과 해석을 가능하게 하며, 실시간으로 변화하는 계통의 구성과 상태를 반영한 전략수립 방법을 고찰한다. 본 논문에서는 해석적 접근에서 방법적 접근방법을 이용한 전압안정도의 지수를 판단하고, 해당 지수에 기반한 취약점 탐색과 토폴로지 구성변경 전략을 제안한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.127-129
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• 2005

We investigated the fault current limiting characteristics according to the various facilities in power system. Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such as short circuits are increasing higher, which causes the ratings of circuit breakers(CBs) to increase. Upgrading or replacement of CBs is not difficult from the technical and economical point of view. Bus split is being adopted into a part of 154 kV power systems, but it has adverse effects such as overload to neighboring power systems, increased voltage fluctuation, and decreased power system stability. For 345 kV power systems, the bus split measure is not feasible and dc reactors are being suggested. The superconducting fault current limiter is a protection gear of new concept that limits fault current automatically in a few milliseconds. It can also provide the effect of CB capacity increase, relaxation of power machine criteria, enhancement in power system reliability, and flexible power system operation.