Dynamic Characteristics and Improvement Measures of Grid-Connected DFIG in Different Control Mode

The dynamic characteristics of wind farms are different from the conventional thermal or hydro power plant, and the dynamic stability between wind farms and power systems is increasingly prominent after a system fault occurs. This paper firstly describes two different control modes of the grid-type double-fed induction generator (DFIG), that is the constant voltage control mode (CVC) and the constant power factor control mode (CPFC). Then the fault dynamic response analysis is conducted through a series of simulates by the well-known power system analysis software FASTEST (Fast Analysis of Stability using the Extended equal area criterion and Simulation Technologies). The results show that CVC-mode DFIGs can serve as reactive power to help the system restore voltage, but that CPFC-mode DFIGs need additional reactive power compensation equipments. So the SVC equipments installed at the point of common coupling help to improve the dynamic characteristics of wind farm and power system. Another FASTEST simulation tests verified the SVC improvement performance.