Analysis and Optimizing Method of Transient Performance for LCL-Based Grid-connected Inverter with Passive Damping

Dynamic currents and voltages in power electronic converters often exceed rating when changing load. In this way, this paper researches on optimizing transient performance of LCL-type gird-connected inverter systems. Resistor connected in series with capacitor as passive damping (RCSCPD), which is widely used to damp resonance of LCL filter, needs to choose an appropriate resistor to acquire accurate and fast transient performance. To meet this requirement, an approach is proposed for analyzing and improving transient performance. It shows that passive resistor could damp resonance and stable system. Limitation of RCSCPD, which could not optimize dominant transient response, is exhibited as well. Hence, mix damping (MD) is proposed to achieve the goal. It could eliminate overshoot and decrease settling time efficiently when comparing with RCSCPD. MD could configure the poles effectively without adding precision sensors because it uses grid current, which used in control loop, to realize active damping resistor. Experimental results based on single-phase LCL-type gird-connected inverter prototype are given to show optimizing effects of transient performance.