Real-Time Monitoring Method for Small-Signal Stability of VSC-HVDC Converter Based on Digital Twin Approach

With the increasing penetration of renewable energy and power electronic switching devices in the power system, the power grid is facing serious challenges. Frequent and intense disturbances propose higher requirements for stability of the power grids. For the purpose of improving the monitoring effect of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) system under small disturbances, a real-time monitoring method of small-signal stability based on digital twin is proposed. Firstly, the state space model of a VSC-HVDC converter system is derived according to its topology and control strategy. Secondly, the small-signal model of the system is further constructed according to the state space model, which is the digital twin of the real system. The twin is driven by the real-time state parameters, the twin data of online simulation computation is obtained, and the monitoring results of small-signal stability of the system are presented in the form of root locus. Finally, results based on the PSCAD/EMTDC-MATLAB co-simulation technology show that the proposed method can effectively establish highly realistic virtual twins, achieving real-time mapping of the system root trajectory in multi-working condition scenarios. It can accurately reflect the small-signal stability of the system. The research outcome lays a foundation for the subsequent realization of system intelligent decision-making and equipment operation management and other auxiliary decision-making functions.