Inertia Response and Frequency Control Techniques for Renewable Energy Sources

Abstract

The penetration level of Renewable Energy Sources (RES) is increasing day by day with integration to the conventional power system in order to produce the electrical power from cheaper and cleaner sources of the energy. This has led to a few stability related issues in the power system. Frequency instability is one of them. Frequency of the power system depends on real power balance. If there is a mismatch between generation and demand, frequency will vary and the Rate of Change of Frequency (RoCoF) is deter- mined by the total system inertia. In converter based wind turbine generators, the power converters decouples 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 obvious that when the power system has a very small amount of inertia or else becomes inertia less, the entire frequency control methodology needs to be redefined and new methods needs to be developed for maintaining frequency. The wind turbine generators, if controlled by modifications in the controllers, will help to improve inertial response to the system. Such controllers will enable the wind turbines for supporting the frequency of the power system. The results for these simulations will be embodied and discussed in the thesis.