Impact Of Distributed Generation On Power System Protection

This dissertation describes a simulation study of the impact of distributed generation (DG) interconnection to an existing distribution system of an Iraq system. The increase load demand in many countries pushes the electrical company to use DG technology to meet their load. From the literature review, it was found in spite of many positive effects of DG such as reduce the power losses and reduce voltage drop; the parallel operation of DG with an existing distribution system has many technical problems. One of the most significant issues of parallel operation is the change of fault level and suitability of existing protection system that indeed needs to be maintained within acceptable limits as defined in the international standards. Therefore, this dissertation is performed to investigate the impact of DG based synchronous generator driven by diesel engine on both the fault level and protection system. A small part of the distribution system in Baghdad capital-Iraq which the DG is currently interconnected at 11kV bus has been chosen and modeled using DIgSILENT PowerFactory version 15. The impacts of DG installation at three different locations, i.e. two possible locations which are 33kV and 132kV buses as well as the actual location have been investigated. The dissertation basically includes two investigations which are; examine the change in the fault level without the presence of DG and with DG interconnection at three interconnection locations by executing three-phase fault at each bus of the network as well as investigate the suitability of protection devices through performing single-line-to-ground and three-phase faults at 33kV and 11kV feeders within the distribution system. The results show that after an extensive simulation study, the increase in short circuit level is noticeable at the buses where the DG is interconnected and the protection performance of unidirectional overcurrent relay suffer from blinding and sympathetic tripping as well as the under reach of distance relay, therefore, a series remedy is needed for safety purposes and to reliability of the system

Government review of the Mod-2 wind turbine (as-built)

The findings and recommendations of the Government committee formed to conduct an as-built review of the three Mod-2 wind turbine units at Goldendale, Washington are given. The purpose of the review was to identify any critical deficiencies in machine components that could result in failure, and to recommend any necessary corrective action before resuming safe machine operation. The review concluded that one of the deficiencies identified would preclude planned attended or unattended operation, provided that certain corrective actions were implemented