孤岛微电网逆变器不平衡负载下的控制策略

提出一种孤岛微电网逆变器在不平衡负载下的控制策略,采用分序网络解耦控制,在虚拟同步发电机(VSG)控制的基础上引入自适应负序补偿环.对三相负载不平衡下的电路进行分析,得到逆变器分序网络等效电路和逆变器间负序环流产生机理.通过分序网络解耦控制得到电压环参考电压各序分量,引入分序网络虚拟阻抗改进逆变器各序输出阻抗.正序网络...

Control strategy of inverter for islanded microgrid with unbalanced load

A control strategy of inverter for islanded microgrid with unbalanced load is proposed, which adopts the sequence network decoupling control and introduces adaptive negative sequence compensation loop based on VSG(Virtual Synchronous Generator) control. Based on analyzing the circuit with unbalanced three-phase load, the sequence network equivalent circuit of inverter and the generating mechanism of negative sequence circulation between inverters are obtained. Sequence network decoupling control is employed to obtain each sequence component of reference voltage of voltage loop, and sequence network virtual impedance is added to improve each sequence output impedance of inverter. VSG control is used in positive sequence network to realize positive sequence frequency and voltage regulation and current autonomous distribution, and negative sequence compensation loop is adopted in negative sequence network to suppress the negative sequence component of three-phase voltage of microgrid. The relationship among the negative sequence component of microgrid voltage, the negative sequence compensation coefficient and the negative sequence component of output current of inverter is analyzed in detail. The adaptive control is used in negative sequence compensation loop to realize three-phase voltage balance of microgrid and the independent distribution of negative sequence component of output current according to the inverter rated capacity. Modeling simulative results verify the effectiveness of the proposed control strategy.