具备无功补偿的NPC三电平光伏并网发电系统的准PR控制

Quasi-PR Control of NPC Three-level PV Grid-connected Generation System with Reactive Compensation

为避免传统方法中复杂的坐标变换和解耦控制,同时提高系统利用率,提出了一种基于准PR控制的中点箝位式(NPC)三电平光伏并网发电系统新型控制策略。该发电系统在白天可同时进行有功功率输出和无功功率补偿,在夜晚仍能实现对负载的无功补偿。准PR控制器的引入实现了在静止坐标系下对交流信号的无静差跟踪,不仅简化了控制算法,而且增强了系统的鲁棒性。同时基于准PR控制原理设计了分次谐波补偿器,大大减小了并网电流的谐波含量。此外,通过反馈上下电容的电压差实现了中点电位平衡控制。仿真结果证明了所提控制策略的可行性和优越性。

In order to avoid the complex coordinate transformations and decoupling control in traditional strategies,a novel control strategy based on quasi-proportion resonant （quasi-PR） control is proposed for neutral point clamped （NPC） three-level photovoltaic （PV） grid-connected generation system to improve the efficiency of the system.The system can not only output active power and compensate reactive power to the grid during the day,but also realize reactive power compensation for load at night.Quasi-PR controller is introduced to achieve zero steady-state error tracing of AC signal under stationary frame,which simplifies the control algorithm and enhances the robustness of the system.At the same time,the respective harmonic compensation controller is designed based on quasi-PR principle,which greatly reduces the harmonics of grid current.In addition,the neutral point balance is realized through the feedback of the voltage difference between the upper and lower capacitors.Simulation results verify the feasibility and superiority of the proposed strategy.