Research on the Voltage Distribution and Short Circuit Features of Distribution Network with High Level of Clean Energy Penetration

Based on the model building of doubly fed induction generation (DFIG) system and photovoltaic (PV) power generation system together with their grid-connection control system and 2 typical structures of power distribution system, i.e. radial structure and tree structure, digital simulations with various penetration levels were performed in the Real Time Digital Simulator (RTDS). The results indicate that the influence of the clean energy power source on the radial structure was the largest; voltage was increased in the PV power injected circuit, but decreased in the wind power injected circuit without reactive power compensation; and the variation is not linear with the penetration. As to the short circuit fault performance, short circuit current provided by the PV power system was low but rich in harmonics at 10$^{th}$ order and above; while the DFIG wind power generator performance was similar to synchronous AC source. However, there was transient surge in both current and voltage at the elimination of fault, imposing attention to the design of equipment insulation and power distribution system structure.