基于虚拟同步发电机的微网逆变器控制策略研究

本文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。根据同步发电机的本体数学模型、一次调频及无功电压调节特性,分别设计了虚拟同步发电机算法、虚拟原动机调节及励磁电流调节模块,同时通过电压电流双环控制,使逆变器输出的电压幅值和频率具有良好的下垂特性、可调的转动惯量及较好的跟踪性能,从而提高了系统的稳定性和可靠性。此外在并网系统中要求频率控制精度高及实时响应的情况下,本文还对虚拟原动机调节模块进行了改进,实现了频率的无误差控制,提高了频率控制的精度和响应速度。最后在matlab/simulink中进行了模型的搭建和仿真,逆变器输出电压很好的模拟了同步发电机的外特性,单相电压的畸变率仅为0.2%,引入改进原动机调节模块后,输出频率不随负荷的变化发生偏移。最终稳定在49.98Hz,验证了本文理论分析的正确性和可行性。

Study of Micro-grid Inverter Control Strategy Based on Virtual Synchronous Generator

The paper studied a kind of micro-grid inverter overall control strategy based on virtual synchronous generator algorithm. According to the body mathematical model of synchronous generator, a modulation of primary frequency and reactive voltage regulating characteristic, designed a virtual synchronous generator algorithm, prime mover adjustment and excitation current adjustment model respectively, at the same time through with better tracking effect of the voltage current double loop control strategy, making the inverter output voltage amplitude and frequency with good droop, the adjustable rotational inertia and better tracking performance and improved the stability and reliability of the system. In addition, in the grid system frequency under the condition of high control precision and real-time response, the paper improved the virtual prime mover control module, and frequency has been achieved without error control, which improved the control precision and response speed of frequency. Finally built model and simulated in the matlab/simulink, inverter output voltage simulate the external characteristics of synchronous generator betterly , single-phase voltage distortion rate of 0.2 percent , and after the introduction of improved prime mover adjustment module , the output frequency does not change with the load shifted, eventually stabilize at 49.98Hz, which verified the correctness and feasibility of the theoretical analysis.