Distributed solar power generation effects on short circuit protection of distribution network: New techniques for improvements regarding adverse effects

Distributed generation is a new application field regarding electricity generation and distribution. As this application grows, the network will face new challenges. One of the candidates for complications that may arise is the possibility of malfunction of the current relay coordination. Circuit breakers may be triggered, although there are no faults. Circuit breakers that must be triggered in the event of a fault might not interrupt the circuit unexpectedly. The network protection systems may lose their function. SAIDI (System Average Interruption Duration Index), SAIFI (System Average Interruption Frequency Index) and EENS (Expected Energy Not Served) values of the network may increase. In this thesis, the wide application of distributed generation (especially solar energy power plants) in the future is investigated and the possible effects on the existing relay coordination are predicted. In the network topology where the solar power plants are connected, the branches are systematically investigated in terms of safety. In order to conduct this investigation, the superposition analysis was applied for the first time in distributed generation short-circuit analysis. As a matter of fact that, the superposition analysis serve practical and easy ways to examine the effects of distributed generation on the distribution network. The literature survey shows that the IEEE 13-Node or IEEE 34-Node radial distribution test feeder topologies have been frequently used when the distribution network is examined. However, instead of using these topologies, an alternative topology which is sufficient and more useful for the required PSCAD simulation has been developed for the sake of simplicity, in this study. In order to obtain realistic results in PSCAD simulations, an Excel-based computing platform (Master Program) was developed that calculates the distribution network circuit parameters to be used in PSCAD. New applications are proposed that will help to reduce the adverse effects that are predicted/identified during all these simulations and investigation studies.