Authors: Jianbo Xin, Xiangning Lin, Zhengtian Li, Hanli Weng
Addresses: Jiangxi Provincial Electric Power Research Institute, Nanchang, 330096, China. ' Department of Electrical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China. ' Department of Electrical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China. ' Department of Electrical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
Abstract: In the first part of this paper, a new model of power system swings applicable for testing the algorithm digital distance protection is proposed. With the investigation of frequency during the transient process, the polynomials are used for fitting the variation of frequency. With this model, the key parameters of power swings can be determined and set to provide enough typical data for the evaluations of the behaviours of all types of relays. The availability of this model is validated with the EMTP simulation tests. Then, a novel fast unblocking scheme for distance protection to identify symmetrical fault occurring during power swings has been proposed in this paper. First of all, the change rate of three-phase active power and reactive power being the cosine function and the sine function with respect to the phase difference between the two power systems during power swings has been demonstrated. Thereafter, the cross-blocking scheme is conceived on the basis of this analysis. By virtue of the algorithm based on instantaneous electrical quantities, the calculation of the active and reactive power is immune to the variation of the system power frequency. As the integration based criterion, it has high stability. Finally, simulation results show that this scheme is of high reliability and fast time response.
Keywords: power systems; protective relaying; power swings; simulation; change rate of power; crossing blocking; modelling.
International Journal of Advanced Mechatronic Systems, 2011 Vol.3 No.1, pp.33 - 43
Published online: 18 Mar 2015 *Full-text access for editors Access for subscribers Purchase this article Comment on this article