Development of Asynchronous Blocking Algorithm through Asynchronous Case Study of Steam Turbine Generator

스팀터빈 발전기 비동기 투입 사례연구를 통한 비동기 방지 알고리즘 개발

  • Received : 2012.08.22
  • Accepted : 2012.09.20
  • Published : 2012.10.01


Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. When calculation method of protection settings and logic for protection of generator asynchronization will be recommended, a distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome asynchronizing protection, this paper describes an improved backup protection coordination scheme using a new logic that will be suggested.


Generator;Synchronous;Asynchronous;Phase angle;Backup protection;Coordination


  1. L. Wang, J. Jatskevich, C. Wang and P. Li, "A Voltage-Behind-Reactance Induction Machine Model for the EMTP-Type Solution", IEEE Trans. on Power Systems, Vol. 23, No. 3, pp. 1226-1238, 2008.
  2. B. Wang, X. Dong, Z. Bo and A. Perks, "RTDS Environment Development of Ultra-High-Voltage Power System and Relay Protection Test", IEEE Trans. on Power Delivery, Vol. 23, No. 2, pp. 618-623, 2008.
  3. Eun-Woong Lee, "The Analysis of Asynchronous Phenomenon and Electrical Characteristics of Synchronous Generator for Peak Load Operation" 전기학회논문지, 제47권 제6호, p719, 1998
  4. Cho Seong-jin외, "A Study on the Development of Protection Relay Applied a Generator protection Basic Algorithm", 대한전기학회 하계학술대회 논문집 A, 2003. 7
  5. IEEE Std.C37.102-2006 "IEEE Guide for AC Generator Protection"_5.7_ Synchronizing
  6. 정창호, 이재규, 정병태, 안복신, "Adaptive 보호범위를 가진 송전선로 보호용 디지털 거리계전기", 대한전기학회 하계학술대회 논문집 C, p7, 1998
  7. 권영진외, "발전기 과도현상에 따른 발전기 보호 계전기 동작 분석", 대한전기학회 전력기술부문회 추계학술대회 논문집, p379, 2006.11
  8. Hyung-Kyu Kim, Sang-Hee Kang, "Improved Coordination Method for Back-up Protection Schemes Based on IEC 61850", 전기학회논문지, 제60권, 제1호, p43, 2011. 1