Power Losses Reduction and Reliability Improvement in Distribution System with Very Small Power Producers

Abstract

The promotion of small-scaled distributed generation, commonly known as Very Small Power Producer (VSPP) in Thailand's electric power industry, is derived from its incentive policy and environmentally friendly attribute. For this reason, distribution systems have seen a high penetration level of VSPPs powered by conventional or renewable energy resources. One of the main benefits for having VSPPs is the improvement of system reliability perceived by customers due to the availability of additional backup generations at the point of common coupling (PCC) during the loss of the main supply as a result of equipment outage without an adjacent feeder to perform open-loop configuration. Such a positive impact can, nevertheless, be only achieved when intentional islanding operation is permitted. In addition, during normal operation, the VSPP normally, but not necessarily, contributes to power loss reduction as the generation energy flow is generally against the major net flow. So the amount of the major net flow transferred over long distance of the power system can be reduced. This paper investigates the impact of VSPP based on power losses and reliability point of view. A case study with an existing urban 24 kV distribution system is presented with sensitivity analysis for the capacities of VSPP, locations of VSPP, and different number of VSPPs. The study results show that the VSPPs are useful as alternative generation resources for power losses reduction and reliability improvement in distribution system. Electric utilities should, however, pay special attention on their existing control and protection scheme in order to have their system to remain integrity.