A Digital Generic Multi-cell Network Control for LCL-filtered Inverters with Different Delay

The active damping of LCL filter, the decoupling of dq-axes injected grid current, and the injected grid current regulator are essential to the control of LCL-filtered grid-connected inverters. Generally speaking, the active damping suppresses resonance peak caused by the LCL filter and help to stabilize inverters, the dq-axes decoupling is to realize the independent regulation of active and reactive power, and the current regulator guarantees the quality of the injected grid current. Recently, digital control is widely used for its flexibility and reliability. However, the inherent delay of digitally controlled system usually can not be ignored when the active damping, decoupling, and current regulator are designed, otherwise inverter performance may be degraded. Based on a continuous-time complex-domain approximate rational model of inverters and the generic multi-cell network control (GMNC) structure, a generic design method of the GMNC for digitally controlled inverters with different delay is proposed. The GMNC with the proposed design method can make digitally controlled inverters obtain similar performance as analog controlled ones, and its effectiveness is verified by simulation results.