基于比例积分谐振的微网逆变器电压均衡控制策略研究

对于工作在离网模式下的微网逆变器,在可能会出现的负载不对称或者单相负载运行场合,采用传统的电压电流双闭环控制方法会导致输出电压严重不平衡,从而危害供电设备以及整个系统。基于分裂电容式的三相四线逆变器系统,针对逆变器在离网模式下带不平衡负载运行的问题,建立相关数学模型分析抑制不平衡问题,分析传统比例积分控制的缺陷,并在此基础上采用正负序分离独立控制和比例积分准谐振控制策略。同时针对微电网运行状态平滑切换的要求,给出一种基于间接电流控制策略的平滑切换控制策略。仿真结果证明该控制策略的正确性。最后在微电网逆变器实验平台上通过实验验证了该方案的实用性和可行性。

Voltage Balance Control Strategy for Microgrid Inverter Based on Proportional Integral Resonance

Under unbalanced or single-phase load, the traditional double closed-loop control method of voltage and current will cause a serious problem of output voltage unbalance to themicro-grid inverter working in island mode, thus endangering the supply equipment and even the overall system. Based on a three-phase four-wire inverter system with split capacitor,a mathematical model is established to analyze how to suppress the voltage unbalance when the inverter works in island mode and with unbalanced load. The shortcomings of the traditional proportional integral(PI) control are analyzed, and a control strategy based on positive and negative-sequence independent control and PI quasi-resonant control isproposed. Meanwhile, to satisfy the smooth switching requirements of microgrid operation states, a smooth switching control strategy is given based on indirect current control. Simulation results prove the correctness of the proposed strategy. Finally, the practicality and validity of this strategy were verified by tests on an experimental platform of microgrid inverter.