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Optimization Strategy of Virtual Synchronous Generator Control for Doubly-fed Induction Generator in Unbalanced Power Grid
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Affiliation:

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

Fund Project:

This work is supported by Zhejiang Provincial Natural Science Foundation of China (No. LZ18E070001).

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    Abstract:

    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.

    图1 转矩-无功谐振控制环Fig.1 Control loop of torque-reactive power resonance
    图1 转矩-无功谐振控制环Fig.1 Control loop of torque-reactive power resonance
    图2 不平衡电网下优化策略控制框图Fig.2 Control block diagram of optimization strategy in unbalanced grid
    图3 VSG控制优化策略仿真结果(目标1)Fig.3 Simulation results of optimization strategy for VSG control (target 1)
    图4 VSG控制优化策略仿真结果(目标2)Fig.4 Simulation results of optimization strategy for VSG control (target 2)
    图5 VSG控制优化策略仿真结果(目标3)Fig.5 Simulation results of optimization strategy for VSG control (target 3)
    图 双馈电机虚拟同步控制框图Fig. Virtual synchronous generator control of DFIG
    图 DFIG等效电路图Fig. DFIG equivalent circuit
    图 双馈电机虚拟同步控制框图Fig. Virtual synchronous generator control of DFIG
    图 SOGI幅频特性伯德图(Kr=50,ωc=1)Fig. Amplitude-frequency characteristic of SOGI
    图 原有虚拟同步控制仿真结果Fig. Simulation results of original VSG control
    图 电网动态变化仿真仿真结果(目标3)Fig. Simulation results of grid dynamic change
    表 1 Table 1 System parameters of DFIG control system
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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/AEPS20190708005

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History
  • Received:July 08,2019
  • Revised:November 26,2019
  • Adopted:
  • Online: May 22,2020
  • Published: