Synthetic Inertia Emulation in Wind Energy based Power System

Abstract

Over the years, penetration of wind based power plants in the power system has increased significantly. This has led to a few stability related issues in the power system. Frequency instability is one among them. Frequency of the power system depends on real power balance. If the balance between generation and demand is not reached, frequency will vary and the rate of change of frequency is determined by the total system inertia. In converter based wind turbine generators, the power converters decouple the power source from the grid. This causes zero contribution to the system inertia from these generators. Hence, although the generation is increased, the total inertia of power system does not. It is to be noted that even though the type 3 wind turbines have partial power owing through the converters, the converters are controlled in such a way that total inertia depends on the action of the converters. The wind turbine generators, if controlled by modifications in the controllers, will help to improve inertial response to the system. These controllers will enable the wind turbines to support the frequency of the power system. In addition, both the over frequency and under frequency response shall be improved. The work presented in this dissertation report describes the stability analysis by evaluating the eigenvalues of the wind turbine based power system. The frequency response of the power system with the proposed controllers is analysed and verified mathematical model of the power system. Simulations carried out using mathematical model of wind energy based power system, eigenvalue analysis for power system having only conventional generators and integration of wind farm in the power system are presented. Also a temporary frequency support scheme is suggested for varying wind condition. The results for these simulations will be embedded and discussed in the thesis.