Multi-terminal DC Transmission System and the Control Strategy for Ecological Restoration in the Mining Area

In order to meet the electricity demand of ecological restoration projects in the mining area, a transmission system scheme combining the utilization of renewable energy and the load electricity of ecological restoration in the mining area was proposed. Based on multi-terminal DC transmission technology, a power channel with controlled power flow between the local microgrid and the external power grids is created to support the local microgrid including wind power and electricity load. The circuit model and impedance model of the multi-terminal HVDC system with local microgrid are established, and the power flow control strategy based on the virtual resistance controller of the main converter station is proposed, and the value range of virtual resistance is given to realize the smooth switching of the working mode of multi-terminal HVDC system. Based on the actual data of the Penglai mining area, the effectiveness of the system scheme and control strategy is verified by simulation.