1.State Grid Corporation of China, Beijing 100031, China;2.Beijing Sifang Automation Co., Ltd., Beijing 100085, China
In December 2018, a 1 810 Hz resonance of AC voltage occurred during the open line test (OLT) of Hubei-side AC system in Chongqing-Hubei back-to-back HVDC project of China (referred to as “Chongqing-Hubei project”). After adopting the typical suppression measures for high-frequency resonance, a 700 Hz resonance of AC voltage occurred during OLT of Chongqing-side AC system. According to the Nyquist stability criterion, this paper adopts the Bode diagram based on impedance theory to study the resonance mechanism of the whole AC/DC system. The impedance characteristics of the flexible DC system and AC systems are analyzed. And the results show that there are risks of resonance near 1 780 Hz and 750 Hz in the flexible DC system and Hubei-side and Chongqing-side AC systems, which basically coincides with the field test. This paper proposes a control strategy based on the voltage feedforward link with the nonlinear filter, which changes impedance characteristics of flexible DC system in middle and high frequency bands to avoid its resonance with the AC system. An electromagnetic simulation model is established to simulate the flexible DC system and AC systems on both sides of Chongqing-Hubei project, and the resonance is reproduced. The simulation results verify the effectiveness of the proposed strategy for resonance suppression. Finally, the proposed strategy has been applied in Chongqing-Hubei project, and no resonance has been observed in typical operation modes.
This work is supported by National Key R&D Program of China (No. 2016YFB0900905) and State Grid Corporation of China (No. 5100-202014009A-0-0-00).
|||GUO Xianshan, LIU Bin, MEI Hongming, et al. Analysis and Suppression of Resonance Between AC and DC Systems in Chongqing-Hubei Back-to-Back HVDC Project of China[J]. Automation of Electric Power Systems,2020,44(20):157-164. DOI:10.7500/AEPS20200211008|