Evaluation of damping controls of a permanent magnet synchronous generator wind system with STATCOM

Large wind farms may pose stability and control issues when integrated to the power system. Although integration of large penetration of wind power into an existing transmission system does not require a major redesign, it necessitates additional control and compensating equipment to enable recovery from severe system disturbances. A variable speed permanent magnet synchronous generator (PMSG) wind generator system is considered in this study. This thesis develops a model of a variable speed wind turbine permanent magnet synchronous generator (PMSG) system including the detailed dynamics of the converter circuitry. The static converters used in PMSG systems decouple the mechanical frequency of the rotor and the electrical frequency of the grid, and are modeled as current controlled voltage sources. A STATCOM device is used to control the system performance in transient as well as in steady state.;The impacts of the location of the STATCOM device on the generator as well as grid side of the converter were investigated and best possible location is examined through small signal analysis. To enhance the operation of the PMSG system, the damping capabilities of the generator and grid side converter controls were investigated using various decomposition techniques through small signal analysis and control design is carried out with the best stabilizing signal for the control input identified. Non-linear time domain simulations have been carried out to validate the findings of the small signal model and also to assess the controller performance in terms of enhancing system operation. It was observed that the modulation index of the generator side-converter has the higher controllability to damp the oscillatory modes of the system when the STATCOM is located at the grid side converter. A PI/PID controller is designed to improve the performance of the wind turbine grid connected system. The controller gains were tuned through a frequency based optimization procedure.