1. 中国南方电网电力调度控制中心, 广东省广州市 510623; 2. 华南理工大学电力学院, 广东省广州市 510641
1. China Southern Power Grid Dispatching and Control Center, Guangzhou 510623, China;2. School of Electric Power, South China University of Technology, Guangzhou 510641, China
Enhanced governors are adopted in some hydroelectric units in Yunnan power grid, which causes the ultra-low frequency oscillation and threatens the frequency stability of power grid seriously. In order to reveal why the enhanced governors of hydroelectric units affect the frequency of Yunnan power grid of China, the theoretic calculation and time-domain simulation are conducted on dynamic behaviors when the system frequency difference across the dead zone of primary frequency regulation from different directions. It is demonstrated that the enhanced governor does not have a stable equilibrium point near the dead zone of primary frequency regulation of hydroelectric generator, and when the system frequency difference slowly passes back to the dead zone, a phase lag of about 90 degrees is introduced in ultra-low frequency band, thus reducing the safe and stable margin of the system frequency. Finally, the eigenvalues of a single-machine system including hydro turbine, governor and generator models are calculated with the aid of small disturbance analysis tools. Through the comparative simulation, it is shown that the enhanced governor not only has similar negative damping effect with the water hammer in ultra-low band, but also is the one of the disturbance sources of ultra-low frequency oscillation, which keeps ultra-low frequency oscillation continuous and unable to attenuate.
HE Yue, ZHANG Yong, CHEN Yiping,et al.Analysis on Impact of Enhanced Governor on Ultra-low Frequency Oscillation in Yunnan Power Grid of China[J].Automation of Electric Power Systems,2019,43(13):185-190. DOI:10.7500/AEPS20190123001.