1.State Key Laboratory of Smart Grid Protection and Control, Nanjing 211106, China;2.NARI Group Corporation (State Grid Electric Power Research Institute), Nanjing 211106, China;3.College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China
This work is supported by Zhejiang Provincial Natural Science Foundation of China (No. LZ18E070001).
When the grid voltage is unbalanced, since the control bandwidth of the virtual synchronous generator (VSG) is limited, it has almost no effective control over the double-frequency fluctuation component of the power caused by the negative sequence voltage of the power grid. Therefore, the long-term voltage imbalance will cause problems such as stator and rotor current distortion, power and torque oscillation in doubly-fed induction generator (DFIG), which seriously affect the output power quality and operation performance in the system. In order to solve these problems, this paper proposes a method to quantitatively control the electromagnetic torque and the double-frequency pulsation of reactive power for DFIG by using the second-order generalized integrator (SOGI). This method enables the VSG control system of DFIG to achieve three control objectives under unbalanced power grid conditions, namely balanced and sinusoidal stator current, sinusoidal stator current and constant active power, sinusoidal stator current and constant reactive power and electromagnetic torque. At the same time, each control target can be flexibly switched according to the real-time requirements of the power grid, which improves the control performance of VSG control system for DFIG. Finally, the effectiveness of the proposed strategy is verified by simulation results.
SUN Jun,JIANG Tianlong,WANG Yangming,et al.Optimization Strategy of Virtual Synchronous Generator Control for Doubly-fed Induction Generator in Unbalanced Power Grid[J].Automation of Electric Power Systems,2020,44(10):135-144.DOI:10.7500/AEPS20190708005Copy