Analysis of Impact of DFIG-based Wind Turbines with Virtual Synchronous Control on the Action Path and Low Frequency Oscillation of Synchronous Generator

In allusion to the impact of doubly fed induction generator (DFIG) based wind turbines (WTs) with virtual synchronous control (VSynC based on low frequency oscillation in power system, firstly, based on internal e.m.f. motion equation of DFIG-based WTs with VSynC and by means of establishing a linearized model of two-machine system both the path, through which the DFIG-based WTs with VSynC acted on the synchronous generator, as well as the physical process were analyzed. Secondly, utilizing damping torque method the mechanism, by which the DFIG-based WTs influenced low frequency oscillation in synchronous generator, was expounded. Finally, the proposed items were verified by the simulation based on Matlab/Simulink. Simulation results show that the phase of internal e.m.f. of DFIG-based WTs with VSynC varies with the variation of phase and amplitude of the internal e.m.f. of synchronous generator and then the active power of synchronous generator is directly impacted, or through impacting the branch, which impacts the terminal voltage amplitude variation of synchronous generator, the active power of synchronous generator is indirectly impacted, so they are the main path through which the DFIG-based WTs with VSynC impacts the damping of synchronous generator. Besides, the damping for low frequency oscillation in synchronous generator can be improved by increasing both virtual inertia time constant and damping coefficient, however the damping for low frequency oscillation in synchronous generator will be worsened while the bandwidth of the voltage control increases.