含不平衡负载的微电网中三相微源逆变器的VSG控制策略

Virtual synchronous generator control strategy of three phase micro-source inverter in microgrid containing unbalanced loads

在离网模式下,微电网中虚拟同步发电机的输出电压易受不平衡负载影响。针对此问题,文章基于一阶全通滤波器(All-Pass Filter,APF)的电压电流正、负序分离方法,利用正序功率和正序电流建立了改进VSG控制模型,改善了VSG输出电压参考。采用比例积分(Proportional Integral,PI)+准比例谐振(Quasi Proportional Resonant,QPR)电压调节器对VSG输出负序电压分量进行控制,论证了PI+QPR调节器抑制负序电压分量的优良性能。最后,仿真结果验证了该控制策略的有效性,该方法有效地改善了三相微源逆变器输出电压的对称性。

The three phase micro-source inverter based on virtual synchronous generator(VSG)control technology is commonly used as an interface for distributed generation in microgrid,but output voltage of three phase micro-source inverter can be deteriorated under the unbalanced load conditions when the utility grid fails.In order to solve this problem,a voltage unbalanced control strategy for the three phase micro-source inverter is proposed.Firstly,a voltage-current positive and negative sequence separation method based on first order all-pass filter(APF)is proposed.Then,a improvement VSG control model is established by used the positive sequence power and positive sequence current component,which can improve the effect of VSG output voltage reference.Besides,the PI plus quasi proportional resonant(QPR)voltage regulator was used to suppression the negative sequence component of the VSG output voltage,and its excellent suppress ability is well proved by comparing characteristics PI with PI plus QPR regulator.Finally,the simulation results verify the correctness and practicability of the proposed control strategy.The proposed method effectively improves the quality of the output voltage of the three phase micro-source inverter.