Analysis of Power quality of grids integrated with Power from multiple Renewable Energy Sources

Abstract

Due to industrialization and connection of more customers to electrical power by power utilities, there is need to generate more power. To reduce global warming effects, power from renewable energy sources is considered in this work. Intermittency of these sources however, can affect the power quality of the grid that they are connected to. Voltage stability is one of the main factors that should be considered when analyzing power quality of electrical networks. This research work presents analysis of the effects of connecting power from different renewable energy sources into the grid. Modelling of power production from solar PV, wind and small hydro was done then power from these sources was injected into three different grids, IEEE 14 bus system, IEEE 39 bus system and the Western Kenya power network. A method of determining the buses and sections that were most likely to be unstable by using bus and branch participation factors was formulated and its performance compared with related works. The proposed methods were tested using the three grids with power integration from wind, solar and small hydro sources. Analysis was done on the effects on voltage stability before and after injection of power from wind power alone, from solar PV power alone from both wind and PV power and from all the three renewable energy sources. The tools used for voltage stability analysis were; voltage profiles, bus Q-V sensitivities, eigenvalues, eigenvectors and Q-V curves. Sizing, placement and connection of D- STATCOM devices for mitigation of the effects of connecting the power from the renewable energy sources on voltage stability was done. The results showed that, wind power integration helped in improving voltage stability, integration of the modelled solar power led to voltage instability in some buses while integrating the three renewables showed improvement on voltage stability. After connection of the modelled D-STATCOM devices, the voltages were improved to the required limits. The results from the three test cases were compared to existing literature works. The Western Kenyan Network was chosen as a practical test case for the analysis with the aim of extraction of opportunities for renewable energy connection into the grid. Determination of the possible nodes for injection was done. The placement and sizing of a mitigation method will also be studied in this thesis. This will help in providing information to the Kenya Power company for future renewable energy generation and grid connection of the power from the sources.