低压微网中三相光伏并网逆变器控制策略研究

Study on control strategy of three-phase photovoltaic grid inverter in low voltage micro-grid

在低压微网中,以三相光伏并网发电系统为对象,分析了三相光伏并网逆变器的数学模型。并网逆变器电流内环采用瞬时电流控制,可以实现系统电流动态跟踪,但是电流内环采用传统PI控制需要功率前馈解耦影响和复杂旋转坐标变换。在瞬时电流控制的基础上,对三相光伏并网逆变器提出一种外环为瞬时功率控制、内环为瞬时电流准比例谐振的控制策略,并采用复传递函数方法分析了PR控制器的动态性能。经过仿真分析,外环瞬时有功无功控制实现了光伏并网逆变器参考功率控制;在光伏并网发电系统输出功率发生突变的情况下,电流内环控制具有快速准确动态跟踪性能,并实现了功率解耦控制,为电网输出高质量电能,仿真结果有效验证了该控制策略的效果。

In low voltage micro grid,the mathematical model of three-phase photovoltaic grid inverter is analyzed which takes the three-phase photovoltaic grid power generation system as the object. Grid inverter current inner loop uses the instantaneous current control which can realize the current dynamic tracing system,but the current inner loop uses the traditional PI control to realize power feed-forward decoupling effect and complex rotating coordinate transformation. On the basis of the instantaneous current control,in this paper,the three-phase photovoltaic grid inverter is proposed a outer loop for the instantaneous power control,and the inner loop for instantaneous current control strategy of proportion of quasi resonant. Through the simulation analysis,instantaneous active reactive power control loop references for photovoltaic grid inverter power control; In photovoltaic grid power system,the output power under the condition of mutations,current inner loop control is featured with fast and accurate dynamic tracking performance,and realizes the decoupling control of power,and outputs high quality power for grid. The simulation results validate the effectiveness of the control strategy.