Impacts of dispersing storage and generation in electric distribution systems. Final report

Small-scale Dispersed Storage and Generation (DSG) connected to the electric-distribution systems provide one alternative to large-scale additions to utility supply and delivery systems. In addition to being generating sources, DSG may also provide benefits to the distribution system by reducing capacity requirements, improving reliability, and lowering losses. This study offers a consistent, unifying methodology for evaluating the dispersion effect of DSG in distribution systems. The evaluation method and models developed compare the distribution systems expanded with and without DSG, using a consistent set of planning and operating criteria. The effects of DSG outages probabilities, diseconomies of scale, and loss savings are explicitly treated. The method also takes into account the effect on the bulk-supply system when DSG is planned and operated for distribution-system needs. To obtain the overall DSG impact on a utility system, the results derived from this methodology can readily be combined with the impact of the technologies assessed from a bulk-supply perspective undertaken in other studies. This assessment methodology would be suitable for use by most utilities since it is based on extant utility planning procedures and data bases, and practical assessment calculating. Application of this methodology for two utilities showed that the distribution capacity and reliabilitymore » benefits are highly site-dependent, and that potentially higher production cost and DSG capital cost may be incurred. The study points to the importance of caution and comprehensive assessment before implementing DSG in the distribution system on a large scale.« less