Operational and Design Considerations for Electric Distribution Systems with Dispersed Storage and Generation (DSG).

摘要

Three studies were performed to examine the operational and planning problems associated with connecting small power sources to an electric distribution system. In one study, the harmonic distortion produced by a subdivision of photovoltaic arrays connected through line-commutated inverters was simulated. In a second study, the protection and safety problems associated with the operation of small ac generators and dc-to-ac inverters were examined. The third study was an assessment of the effects of dispersed power sources on distribution planning and design. The purposes of the studies were to determine the adequacy of the electric utility industry's current practices, hardware, and design for the operation of dispersed electric power sources; to make recommendations for accommodating this new technology; and to identify areas needing further research. Results of the studies indicate that (1) only minor changes in operation, protection, and maintenance practices and hardware may by required for low penetrations of dispersed storage and generation (DSG) devices; (2) if a line-commutated inverter is used for dc-to-ac conversion, the placement of capacitors to supply the reactive power consumed by this type of DSG device or an induction generator must take into account the amplification of the inverter harmonics by the capacitors; and (3) dispersed generation in significant concentrations can have beneficial affects at the distribution feeder level in terms of reduced voltage drop, losses, and breaker currents, although these benefits may be less significant than the concerns associated with distribution transformer load increases, backfeeding, and increased kVAR requirements. Integration of high penetrations of both small- and large-capacity DSG into the electric distribution system will require more extensive communications between the protection and other distribution equipment and DSG devices, as well as greater control of both distribution equipment and DSG. (ERA citation 10:000493)