Decentralized Robust Emergency Voltage Control of Power System with Large-scale Wind Power Integrated Via VSC-MTDC

Continuous displacement of conventional power plants by wind turbines significantly weakens the dynamic reactive power support ability of power grid. To correct nonviable or unstable voltages and avoid an imminent long-term voltage instability, this paper proposes a decentralized robust emergency voltage control strategy of power system with large-scale wind power integrated via voltage source converter based multi-terminal direct current system (VSC-MTDC). Firstly, a partition approach combining electrical distance and network structure is proposed. The electrical distance expectation considering wind power volatility is calculated in the partition, combined with the edge betweenness, the decoupling of reactive power/voltage control in each zone is realized by community detection. Secondly, a decentralized robust emergency voltage control strategy based on tube-based model predictive control (MPC) approach is innovatively proposed. In the proposed local emergency voltage control model, by treating the action of controllers in other zones as disturbances and compensating them using tightened constraints and ancillary controller, it achieves a robust voltage control in the absence of communication among local controllers. Finally, simulation results are shown with a modified IEEE Nordic Test System, which validates the effectiveness and superiority of the newly proposed strategy.