Voltage and frequency fluctuation risk and simulation evaluation of UHVDC sending network with high renewable energy penetration

With fast development of wind and solar energy resources in China, a type of UHVDC sending power grid with high proportion of renewable energy has emerged. In this paper, typical scenarios of voltage and frequency fluctuation in such power grids are analyzed, i.e., transient high voltage caused by DC fault or disturbance, low frequency caused by a large number of new energy units tripping, and high frequency caused by local power grid disconnection. It is pointed out that the directions of component modeling that should be strengthened in order to improve the accuracy of voltage and frequency fluctuation simulation, which include the simulation of generator auxiliary control of excitation system and the simulation of speed control of generator with dynamic system. The simulation evaluation process and the concerned precautions of UHVDC sending network with high proportion of renewable energy are put forward, which can provide references for the prevention and control of voltage and frequency fluctuation risk in actual power grid.