运行方式及工程等效对PSS试验的影响

研究了运行方式变化和工程等效对测量励磁系统无补偿相频特性的影响。首先阐释了PSS增加阻尼的原理和无补偿相频特性的工程等效测量方法。其次基于对单机无穷大系统的理论分析,得出发电机有功功率和无功功率是影响无补偿特性测量的主要因素。然后进行了实际电网仿真,得到了无补偿特性主要受发电机有功功率、无功功率影响的结论。电网负荷、电气距离、并列机组数量、并列机组PSS投退对试验结果影响较小。最后通过仿真对比,发现采用机端电压等效发电机内电势会使后半频段滞后角度偏大,得到了采用单机无穷大系统代替实际电网将使全频段滞后角度偏小的结论。该成果对于PSS性能的改善具有积极意义。

Impact of operation conditions and engineering equivalent on PSS test

This paper investigates the influences of operation conditions change and engineering equivalent on the uncompensated phase-frequency characteristics measurement of excitation system. Firstly, the principles of PSS increasing damping and the engineering equivalent measurement method of phase-frequency characteristics are elucidated. Secondly, based on theoretical analysis of single-machine infinite bus system, it is concluded that the active power and reactive power of generators are the main factors that influence the measurement of uncompensated characteristics. Then the actual power grid simulations are made, drawing a conclusion that the uncompensated characteristics are mainly affected by the active power and reactive power of the generator. Power grid load, electric distance, number of parallel units, and whether the PSS of parallel units are on or out have less influences on test results. Finally, through the simulation comparison, it comes to a conclusion that employing terminal voltage as the equivalent of internal electromotive force will cause the rear half band lag angle get larger and replacing the actual grid with a single-machine infinite bus system will make the full-band lag angle get smaller. The achievements obtained in this paper have a positive significance to improve the performance of PSS. This work is supported by National Natural Science Foundation of China (No. 51777074), Natural Science Foundation of Hebei Province (No. E2015502013), and Fundamental Research Funds for the Central Universities (No. 2018YQ03).