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남순열(Soon-Ryul Nam),최준호(Joon-Ho Choi),강상희(Sang-Hee Kang),민상원(Sang-Won Min) 대한전기학회 2009 전기학회논문지 Vol.58 No.5
A Method for detection of saturation of a current transformer (CT) is proposed. The algorithm is initiated when the end point of a saturation period is detected. This detection is achieved by checking the time interval between the adjacent zero-crossing points of the second derivative of the secondary current. Once the end point of the saturation period is detected, the beginning point of the corresponding saturation period is determined by backward examination of the sum of the secondary current from the end point. The performance of the algorithm was evaluated for a-g faults on a 345 ㎸ 100 ㎞ overhead transmission line. The Electromagnetic Transient Program (EMTP) was used to generate fault current signals for different fault inception angles and different remanent fluxes. The performance evaluation shows that the proposed algorithm successfully detects the saturation period even in the presence of a remanent flux.
코사인 필터와 사인 필터의 이득차를 이용한 주파수 측정
南淳烈(Soon-Ryul Nam),姜相熙(Sang-Hee Kang),朴鍾根(Jong-Keun Park) 대한전기학회 2006 전기학회논문지A Vol.55 No.6
A new algorithm for estimating power frequency is presented. Unlike conventional algorithms, the proposed algorithm is based on the fact that the magnitude gains of cosine and sine filters become different when the power frequency is deviated from the nominal value. This makes the algorithm capable of providing an accurate and fast estimate of the power frequency. To demonstrate the performance of the developed algorithm, various computer simulated data records are processed. The algorithm showed a high level of robustness as well as high measurement accuracy over a wide range of frequency changes. Moreover, the algorithm was highly immune to harmonics and noise.
PSS/E를 이용한 제주계통의 DFIG 풍력발전단지 및 HVDC 동적모델 개발
남순열(Soon-Ryul Nam),강상희(Sang-Hee Kang),남해곤(Hae-Kon Nam),최준호(Joon-Ho Choi) 대한전기학회 2011 전기학회논문지 Vol.60 No.12
Since main portion of the required electric power in Jeju Island is provided from the mainland through two HVDC lines, Jeju HVDC has a most significant impact on Jeju power system. Average wind speed of Jeju Island is the highest among several candidates in South Korea. So, Jeju Island has been a suitable site for the construction of wind farms where several wind farms are now operating and several others to be sited. Since the large-scale wind generation could have adverse impacts on the stable operation of Jeju power system, wind power is also important for the stability of Jeju power system. Therefore, accurate modeling of Jeju HVDC and wind farms is required for stability analysis of Jeju power system. In this paper, PSS/E-based dynamic modeling of Jeju HVDC and DFIG wind farms is proposed. Model-writing technique of PSS/E is used to develop USRAUX model and USRMDL model for controlling the frequency of HVDC and imposing an operation limit of wind power, respectively. Dynamic characteristics of Jeju HVDC and DFIG wind farms are analyzed through the dynamic simulations. The simulation results show the effectiveness of the developed models for Jeju power system.
커패시터의 최적 스케줄링을 고려한 ULTC의 협조 제어
朴鍾泳(Jong-Young Park),南淳烈(Soon-Ryul Nam),朴鍾根(Jong-Keun Park) 대한전기학회 2006 전기학회논문지A Vol.55 No.6
This paper proposes a coordinated control method for under-load tap changers (ULTCs) with shunt capacitors to reduce the operation numbers of both devices. The proposed method consists of two stages. In the first stage, the dispatch schedule is determined using a genetic algorithm with forecasted loads to reduce the power loss and to improve the voltage profile during a day. In the second stage, each capacitor operates according to this dispatch schedule and the ULTCs are controlled in real time with the modified reference voltages considering the dispatch schedule of the capacitors. The performance of the method is evaluated for the modified IEEE 14-bus system. Simulation results show that the proposed method performs better than a conventional control method.