Voltage Stability Investigation of Power Systems with Grid-Connected Wind Turbine Generators: A Case Study of the Nigerian Distribution System
Abstract:
Wind energy is one of the fastest growing technologies in energy generation industry nowadays. As wind energy is increasingly integrated into power systems, the stability of the existing power systems is becoming a concern and of utmost importance to the power system engineers and operators. The subject of voltage variation at the Point of Common Coupling (PCC) is very crucial to the consumers. This voltage variation is as a result of variable nature of wind turbine power output, which is a function of the wind speed. A load-flow analysis, therefore, needs to be carried-out to ascertain the effect on the test distribution grid with and without the connection of wind turbine generators. Only a small part of Lagos (test) Distribution system is considered in this research work. The purpose of carrying-out load-flow analysis is to evaluate the voltage at each bus, its phase angle and the total loss on the system. Due to high Resistance/Reactance (R/X) ratio of the distribution lines and the radial nature of distribution network, the usual load-flow methods used for transmission network are not adequate for distribution system. To further evaluate the impact of the wind turbine generators on the test distribution network, a dynamic stability was carried out to see if the turbine generator will stay in service during and after the fault is cleared. The stability assessment carried out in this work involves the following: Modelling of the test distribution network components for both static and dynamic stabilities, the mathematical model of the grid parameters and the simulation using Matlab/Simulink (SIMSPOWER Tools) software for dynamic stability. The results of the load-flow analysis show that connection of wind turbine to this test distribution system improves the voltage profile at each bus and it also minimizes the loss on the system’s lines. The dynamic stability results show that the Doubly-Fed Induction Generators (DFIGs) have positive influence on the distribution system especially when a single-line to ground fault was applied at 33-kV bus when the generator was in voltage regulation mode ORDER COMPLETE MATERIAL FROM CHAPTER 1-5
