微网虚拟同步发电机下的自适应滑模控制策略

虚拟同步发电机(virtual synchronous generator,VSG)通常用作微网逆变器中各种分布式电源的接口,以便使系统具有更大的惯性。负荷中的不平衡和非线性负载会对逆变器输出电压造成的影响。为此,设计了一种电压自适应滑模控制器。以VSG作为基础控制器,然后根据系统在αβ坐标系下的方程,将系统的负载电流作为扰动,设计自适应扰动补偿,使系统能在保持稳定的条件下,减少输出电压的抖振。最后,对控制策略进行仿真,结果验证了控制策略在电压不平衡与谐波抑制方面的有效性与鲁棒性,提高了微网逆变器输出电压的电能质量,减少了并联逆变器之间的环流。

An Adaptive Sliding Mode Control Strategy for the Virtual Synchronous Generator of the Micro-grid

The virtual synchronous generator (VSG) is usually used as an interface for various distributed generation in a micro-grid inverter to increase system inertia.Unbalanced and nonlinear loads will affect the output voltage of the inverter.For this reason,this paper designs a voltage adaptive sliding mode controller.Using VSG as basic controller and based on the system equations in theαβcoordinate system,this paper uses system load current as disturbance to design an adaptive disturbance compensation to reduce chattering of the output voltage under the condition that the system remains stable.Finally,the result of simulation of the proposed control strategy verifies that it is effective and robust with respect to voltage unbalance and harmonic suppression,thus improving the power quality of the output voltage of the micro-grid inverter and reducing circulating current between paralleled inverters.