基于状态矩阵的构网型多变流器系统高精度建模方法OA

[Objective]In the simulation of grid-forming multi-converter systems,traditional LC equivalent model exhibits insufficient accuracy and significant transient response errors,rendering them struggle to accommodate high-frequency switching characteristics,particularly failing to accurately represent switching transient processes at sub-microsecond simulation time step.To resolve the above challenges,a high-precision modeling method for grid-forming multi-converter system based on state matrix is proposed.[Methods]Firstly,a discretized model for converter switching components under grid-forming virtual synchronous generator control was established,where undetermined parameters were determined by combining discrete circuit with ideal switching characteristic,thereby constructing a generalized fixed-admittance switching(FAS)model based on LC equivalent circuits.Secondly,based on the coupling characteristics of grid-forming multi-converter,an extension method from the single converter state matrix to the multi-converter system was derived,and system-level state-space equations were formulated to efficiently characterize dynamic interactions among converters.Finally,a grid-forming multi-converter system simulation model was established based on the PSCAD/EMTDC platform,and compared the proposed FAS model with the PSCAD ideal model and traditional LC equivalent model.[Results]The simulation results showed that the simulation results of proposed FAS model were closer to the PSCAD ideal model,which effectively reduced the power loss under the sub-microsecond simulation time step and improved the system simulation accuracy and efficiency while maintaining the system stability.[Conclusion]The proposed FAS model exhibits excellent applicability and stability under sub-microsecond simulation time step.