Abstract:

Study on overvoltage and insulation coordination can provide basic technical support for the implementation of Zhoushan multi-terminals VSC-HVDC （voltage sourced converters based high voltage direct current） project. In order to determine the protection configuration of arrester scheme and the insulation level of equipment, integrated design was carried out and the main circuit parameters of the project were proposed, as well as the main wiring. According to the control strategy of Zhoushan multi-terminals VSC-HVDC project, the electromagnetic transient simulation model was established. The capacitance of sub-module in converters, the type of transformer, the inductance of arm reactors and DC reactors, the grounding modes and the selection of cable parameters all influenced simulation results significantly in the model. Based on the detailed research, the equipments’ parameters were selected and used for the overvoltage simulation, the insulation levels of main equipments were determined as well. As the key equipment in this project, the DC cable’s insulation margin was suggested to be 30% in order to ensure the safe operation, and its insulation level was finally determined to be 510 kV. The research results have been applied in Zhoushan multi-terminals VSC-HVDC project, which can provide references for other similar projects.

Key words: multi-terminals VSC-HVDC system, overvoltage, insulation coordination, main equipments parameters