Accurate Modeling Simulation and Experimental Study of Hybrid Multi-Terminal UHVDC Transmission System

This study researches on the Wudongde hybrid multi-terminal Ultra High-Voltage Direct Current Transmission (UHVDC) project (referred to as Wudongde transmission project in short) from the electromagnetic transient model and simulation and establishes an accurate simulation model of the hybrid multi-terminal UHVDC transmission system with the Power Systems Computer-Aided Design (PSCAD). The hybrid multi-terminal UHVDC transmission system consists of the primary system and the control system. The simulation model of the primary system adopts the parameters of the Wudongde transmission project, and the simulation model of the control system refers to the control system benchmark model of HVDC transmission and 9-terminal DC grid in the International Council on Large Electric Systems (CIGRE). According to the characteristics of the hybrid multi-terminal UHVDC control system, the benchmark model of HVDC transmission and 9-terminal DC grid control system in the CIGRE is modified accordingly, and a simulation model of the control system applicable to the hybrid multi-terminal UHVDC transmission system is established. The accuracy and credibility of the model are verified through the comparison of the recording waveform and the simulating waveform of the steady-state and transient operation. The simulating and field recording waveforms show that the model can accurately simulate the Wudongde transmission project and be used as an effective tool for further studying the electromagnetic transient characteristics of the hybrid multi-terminal UHVDC transmission system.