Impact of green power generation on distribution systems

This paper discusses green power distributed generation (DG) sources (of 10 MW or less), which are connected to the utility system at the distribution level, and their impact on distribution system reliability. Distribution circuits are designed to supply radial loads. Therefore, the introduction of green generation can result in: redistribution of fault and load currents on the feeder circuit, overvoltage and ferroresonance, plus a possible loss of protection system coordination-all of which can result in customer outages. The paper also discusses the specific reliability and protection issues in interconnecting green power generators to utility systems to mitigate the above cited reliability issues. These issues are not adequately discussed in IEEE standard 1547, which addresses interconnection of DG to utility systems.