基于虚拟同步发电机的微网逆变器控制研究

Control strategies of inverters based on virtual synchronous generator in a micro-grid

研究了一种基于虚拟同步发电机算法的微网逆变器控制策略,并分别设计了虚拟同步发电机算法、虚拟原动机调节及虚拟励磁电流调节模块,通过电压电流双环控制,使逆变器输出的电压幅值及频率分别与无功功率及有功功率呈现良好的下垂特性、且能够较快的跟踪负荷的变化,从而提高了系统的稳定性和可靠性。此外文章对虚拟原动机调节模块进行了改进,能够实现频率的实时无差控制,提高了频率控制的精度和响应速度。仿真结果表明,逆变器输出电压较好的模拟了同步发电机的外特性,且相电压的畸变率仅为0.2%,同时输出频率不随负荷的变化发生偏移,可稳定在49.98Hz,验证了文章理论分析的正确性和可行性。

The paper studied a kind of micro-grid inverter overall control strategy based on virtual synchronous generator algorithm. Designed virtual synchronous generator algorithm,prime mover adjustment and excitation current adjustment model respectively,meanwhile with the voltage current double loop control strategy,made the inverter with good droop characteristic of output voltage amplitude and reactive power as well as frequency and active power,which can track the changing load quickly and improve the stability and reliability of the system. In addition,the paper improved the virtual prime mover control module,which can achieve the frequency real-time control without error,and improved the control precision and response speed of frequency. Finally simulation results showed that inverter output voltage simulated the external characteristics of synchronous generator well and the phase voltage distortion rate was only 0. 2 percent,meanwhile the output frequency was stabilized at 49. 98 Hz and did not change with the changing load,which verified the correctness and feasibility of the theoretical analysis.