Distributed Cooperative Disturbance-Rejection Control of Hybrid Alternating Current/Direct Current Distribution Grids with Multiple Inverters

Voltage stability control in distribution grids faces challenges due to strong nonlinearity, modeling error of power electronic devices, and external disturbances. Distributed cooperative disturbance-rejection control of multiple inverters is a novel and promising approach to improve voltage stability in distribution grids. First, the high-dimension model of inverters is simplified into an equivalent input-output model. An extended state high-gain observer is utilized to estimate the effects of multiple disturbances in the equivalent model. Then, a distributed cooperative control strategy for multiple converters is designed based on the consensus theory, achieving coordinated voltage control and active disturbance suppression by integrating the disturbance estimation results. To ensure the dynamic performance of the distributed controller, an optimal topology selection method is proposed based on the graph theory and network control system. A test system consisting of four inverters is built in PowerFactory to verify the proposed control strategy. The simulation results show that the proposed control strategy effectively realizes coordinated voltage tracking control and suppress external disturbances.