逆变型分布式电源控制系统的设计

CONTROLLER DESIGN FOR INVERTER-BASED DISTRIBUTED GENERATION

分布式发电系统并网运行时外特性控制是关系到其应用的关键问题之一。根据并网分布式电源的可控拟负荷外特性,设计了采用电流正弦脉宽调制(PWM)调节方法的电压型逆变控制器,整个体系充分考虑提高电能质量水平。该控制器的核心采用含有直流电压波动前馈补偿的双环串级PI结构。第1级为功率调节器,选择公共连接点(PCC)电压、电流作为反馈量,有功、无功可以分开独立调节;第2级为电流调节器,选择逆变器输出电流作为反馈量,考虑电流反馈解耦补偿,响应速度快。直流电压前馈补偿则可以降低直流侧缺少储能引发输入电压波动对控制效果的影响。输出滤波器的考虑则可进一步提高电能质量水平。仿真结果表明电流正弦PWM的双环串级PI控制系统能够较好地维持逆变型分布式电源恒功率电压源的拟负荷外特性,简单实用、设计灵活,可以得到较好的谐波注入。

How to control parallel operating distributed generation (DG) is one of the issues in application. Based on the proposed controllable quasi-load external characteristic of DG, an integrated control system is designed which adopts current sine-PWM regulation for voltage source inverter (VSI) of interconnected DG. The core of the controller is the infrastructure of double feedback loop and series PI regulators with DC voltage variation feed-forward compensation. The outer loop is power regulators, and the voltage and the current at the PCC are feed-backed. Active and reactive power can be regulated separately. The inner loop is current regulators that have rapid response with decoupled components compensator and the current at the inverter terminal is feed-backed. DC voltage feed-forward compensation may reduce the negative effect due to the lack of storage at the DC side. The output filter can further improve power quality. Simulation results show that the designed control system can properly maintain the constant power voltage source external characteristics of DG. The proposed design is flexible and a low harmonics penetration is obtained.