Voltage Stability Enhancement using VSWT with Direct Drive Synchronous Generators

This paper investigates about the enhancement in grid voltage stability while integrating the large-scale variable speed wind turbine (VSWT) with direct drive synchronous generators (DDSG). A dynamic modeling and simulation of a grid connected VSWT driven DDSG with controllable power inverter strategies suitable for the study was developed, tested and verified. This dynamic model with its control scheme can regulate real power, maintain reactive power and generate voltage at different wind speeds. For this paper, studies were conducted on a standard IEEE 14 bus system augmented by a radially connected wind power plant (WPP) which contains 100 wind turbine generators (WTG). The studies include examining the voltage stability (λ-V) curves, voltage magnitude, reactive power delivered, loading margin and voltage collapse of the system. These voltage stability studies are done for the normal state as well as for line contingencies. It is found that large scale VSWT with DDSG at the transmission level has the potential to improve the long-term voltage stability of the grid by injecting reactive power with the help of controllable power inverter strategy.