不平衡电压下的虚拟同步发电机控制方法

摘要

电网在运行过程中经常出现电压不平衡的状况,通过改变逆变器的控制策略可以改善不平衡条件下逆变器的运行性能.虚拟同步发电机在三相逆变器的基础上,具有可改善逆变器运行性能的特性.为实现对逆变器在离网状态下不平衡电压的控制,通过d-q坐标系下电感电压正负序解耦控制,同时利用VSG能够为电网提供惯性的特点,使逆变器交流侧实现三相电压平衡.改善了离网不平衡状态下负序电压对电网的影响,从而抑制了逆变器输出有功功率的波动,提高了系统的稳定性.通过仿真实验证明所提方法的有效性.%The voltage imbalance occurs frequently during the operation of the power grid. By changing the control strategy of the inverter,the running performance of the inverter can be improved under the unbalanced condition.On the basis of three-phase inverter,the virtual synchronous generator has the characteristics of improving the performance of inverter. In order to realize the control of the unbalanced voltage of the inverter in the off-grid condition,the decoupling control of the inductive voltage was carried out by the d-q coordinate system.At the same time,the VSG could provide inertia for the grid characteristics,which made the inverter AC side achieve three-phase voltage balance. The influence of the negative sequence voltage on the grid was improved,which suppressed the fluctuation of the active power of the inverter and improved the stability of the system.The validity of the proposed method is proved by simulation experiment.