Study on Cooperative Control Strategies of Back-to-Back Dual-PWM Converter

Dual-PWM converter can simultaneously realize multiple control functions,so it has been used increasingly and widely in renewable energy sources and power system.Taking dual-PWM converter as research object,firstly its dynamic mathematical model is built.For the purpose of implementing its multi control functions,a dual closed-loop controller for voltage source converter(VSC) composed of dual-PWM converter is designed and based on the built d-q synchronous rotational coordinate mathematical model of VSC the inner-loop control strategy of the dual closed loop controller to implement decoupled control for output current of VSC as well as the multi outer-loop control strategies to implement constant DC voltage,AC voltage tracking and dynamic power control in four quadrants are researched.By means of digital simulation,not only dynamic cooperative response characteristics of different outer-loop control strategies implemented by the two VSCs in dual-PWM converter are investigated,but also the feasibility of the proposed control strategies is verified by simulation results.