Cooperative control method of multi-source grid-forming converters in weak electrical grids
Virtual Synchronous Generator(VSG),as one of the primary technologies in grid-forming controls,provides inertia support to the power grid.However,due to the limited capacity of individual converters,when larger inertia support is required,multiple VSGs must run in parallel,making the coordinated control of multiple VSGs a subject of significant interest.In this regard,a state-space model for multiple VSGs in parallel is established,and the system stability is analyzed through the eigenvalues of the state variable matrix.Concurrently,a coordinated control strategy for multiple VSGs based on model predictive control is proposed,which introduces the angular frequency deviation and power angle difference as performance indicators to design the objective function.The optimal active power increment required is solved,and the output angular frequency is dynamically adjusted through the power-frequency coefficient,enabling active support for the output frequency and effectively suppressing system frequency fluctuations caused by VSG paralleling,thus the grid stability is enhanced.The results indicate that,compared with the conventional VSG paralleling systems,the proposed MPC-VSG parallel control method can shorten the transient response time of the system and improve its robustness under transient conditions.The simulation result confirms the effectiveness of the proposed approach.
grid-forming convertervirtual synchronous generatorstate space modelmodel predictive controlinertia support
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