• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.224-226
• /
• 2004

Flexible AC Transmission System (FACTS) can greatly reinforce power systems through improvement of power transmission capacity and utilization of equipment under the circumstance of continuous load growth and deregulation SVC and STATCOM are shunt FACT devices that have similar static characteristics with Mwhuical Swikhed Capacitor (MSC). The main issue of this paper is the analysis of different dynamic characteristics when STATCOM is solely adopted and when STATCOM is adopted with combination of other reactive power compensator such as SVC and M5C. Furthermore, better application of reactive power compensators can be clarified through analysis of dynamic characteristics of various combinations of reactive power compensators.

• Journal of Electrical Engineering and Technology
• /
• 제7권5호
• /
• pp.689-697
• /
• 2012

This paper proposes a new coordinated voltage control scheme between STATCOM (Static Synchronous Compensator) and reactive power compensation devices, such as shunt elements(shunt capacitor and shunt reactor) and ULTC(Under-Load Tap Changer) transformer in a local substation. If STATCOM and reactive power compensators are cooperatively used with well designed control algorithm, the target of the voltage control can be achieved in a suddenly changed power system. Also, keeping reactive power reserve in a STATCOM during steady-state operation is always needed to provide reactive power requirements during emergencies. This paper describes the coordinative voltage control method to keep or control the voltage of power system in an allowable range of steady-state and securing method of momentary reactive power reserve using PSS/E with Python. In the proposed method of this paper, the voltage reference of STATCOM is adjusted to keep the voltage of the most sensitive bus to the change of loads and other reactive power compensators also are settled to supply the reactive power shortage in out range of STATCOM to cope with the change of loads. As the result of simulation, it is possible to keep the load bus voltage in limited range and secure the momentary reactive power reserve in spite of broad load range condition.

• 한국산학기술학회논문지
• /
• 제16권4호
• /
• pp.2737-2743
• /
• 2015

풍력발전은 풍력단지가 전력계통과 접속되는 모선의 전압을 유지 또는 제어하기 위한 충분한 무효전력을 공급할 수 있어야 한다. 하지만 풍력단지와 계통 접속점(POI - Point of Interconnection) 모선을 연결하는 선로의 무효전력 손실 때문에 풍력터빈의 무효전력공급은 접속점의 전압을 제어하기에는 불충분하다. 이 문제는 접속점에 STATCOM(Static Synchronous Compensator)과 같은 부수적인 무효전력 보상장치를 설치하여 해결할 수 있다. 본 논문에서 제시하는 STATCOM과 Switched-Shunt, 탭변환 변압기와 같은 기존의 무효전력 보상장치의 협조제어를 사용하면 더욱 효과적으로 접속점 모선의 전압을 제어할 수 있다. 본 논문에서 제시한 방법을 이용하여 초기부하에 대하여 임의의 부하 변동률을 가지는 모의 시스템에 적용한 결과 접속점 모선의 전압강하는 60%이상 개선되었고 부하 모선의 전압은 정격전압의 95%이상을 유지하였다.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권4호
• /
• pp.159-164
• /
• 2005

Various compensators are installed into the power system to operate the system economically and stably by maximizing the availability of utilities and power transmission capability. Fixed Capacitor(FC), Mechanical Switched Capacitor(MSC), and FACTS(Flexible AC Transmission Systems) are used to regulate voltage and power flow of the system. When a disturbance occurs in the power system, the Fixed Capacitor operates dependently on the voltage of the power system and cannot change the amount of installation automatically. But compared to other equipment, the Fixed Capacitor is more economical due to its low cost. Since MSC can change the amount of installation according to the state of the power system, operates more effectively than the Fixed Capacitor. FACTS have fast dynamic performance for the transient condition, but the cost is high. Therefore, it is needed to develop an optimized installation planning for the reactive power compensators by considering their dynamic performance and cost. In this paper, an optimized compensator combination and the proposed scheme is proposed and it is applied to KEPCO system in order to show its capabilities.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 하계학술대회 논문집
• /
• pp.443-446
• /
• 1991

In the conventional current control methods for the current-type reactive power compensators, it is usual to compare the reactive reference current signal with the triangular wave and hence to generate the ON-OFF signals for the semiconductor reactive power compensator. To improve the response as well as the control capability, the delta modulated current control technique is proposed in this paper and studied theoretically.

• Journal of Electrical Engineering and Technology
• /
• 제12권1호
• /
• pp.53-63
• /
• 2017

The increasing of wind power penetration level presents challenges in classical optimal reactive power dispatch (ORPD) which is usually formulated as a deterministic optimization problem. This paper proposes a two-stage stochastic programming model for ORPD by considering the uncertainties of wind speed and load in a specified time interval. To avoid the excessive operation, the schedule of compensators will be determined in the first-stage while accounting for the costs of adjusting the compensators (CACs). Under uncertainty effects, on-load tap changer (OLTC) and generator in the second-stage will compensate the mismatch caused by the first-stage decision. The objective of the proposed model is to minimize the sum of CACs and the expected energy loss. The stochastic behavior is formulated by three-point estimate method (TPEM) to convert the stochastic programming into equivalent deterministic problem. A hybrid Genetic Algorithm-Interior Point Method is utilized to solve this large-scale mixed-integer nonlinear stochastic problem. Two case studies on IEEE 14-bus and IEEE 118-bus system are provided to illustrate the effectiveness of the proposed method.

• 대한전기학회논문지
• /
• 제41권3호
• /
• pp.244-252
• /
• 1992

This paper describes a reactive power compensator using current-source delta modulation converter, which compensates the reactive power in the ac sides of 3-phase rectifier. In the conventional current control methods for the current-type reactive power compensators, it is usual to compare the reactive reference current signal with the triangular wave and hence to generate the ON-OFF signals for the reactive power compensator. To improve the response as well as the control capability, the delta modulated current control technique is used in this paper. As a result, the input power factor is improved close to unity and both simulation and experimental results show good compensating performances.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
• /
• pp.66-68
• /
• 2004

The current source HVDC using thyristor valves requires the reactive power compensator, the increasement of short circuit ratio(SCR) by AC source, and the harmonic filter in power transmission. The voltage source HVDC that controls active power and reactive power independently can minimize the requirements and also can be used as a reactive power source without additional reactive power compensators. In this paper, the solution of supplying active power using direct current transmission and compensating additional reactive power at the heavy load zone in metropolitan area is proposed and verified by simulations.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
• /
• pp.269-271
• /
• 2006

In power system, the reactive power is closely associated with voltage. In addition Reactive power has localized characteristic. Recently wide area blackout caused by reactive power imbalance. Therefore it is important to control reactive power considering its characteristic. Until now maintenance of system voltage has been controlled by shunt compensation rather than generators. However because of a large time-constant, shunt compensators are difficult to manage disturbances immediately. In addition shunt compensation has discrete characteristic, which make disturbances in system. In this paper we studied the voltage maintenance method of local buses by controlling the reactive power output of a generator which is closely related a load bus in addition the proposed method was verified by test system.

• 전기학회논문지
• /
• 제59권6호
• /
• pp.1011-1016
• /
• 2010

It is an important issue to electric power system operations that it can reliably supply large-capacity power to consumption area as due to increasing power demand growth. For this purpose, The FACTS equipment based on Power IT technology with the existing mechanical compensators has been applied to power system. Therefore we suggest on this paper that a plan for coordination control of multiple power compensation equipment in order to increase the utilization of each facility and secure operation margin capacity. As the result of simulation, it is possible to cope actively with a suddenly changed power system. This helps greatly for the voltage stability and supply reliability in a suddenly changed power system.