A Study on Management for a Group of Distributed Generators Aimed at the Cooperation with the Bulk Power System

Abstract

Recently, the basic framework of electric power systems has been changed significantly by deregulation of electric power industry. Also, distributed generators (DGs) such as renewable energy generations, co-generations, and energy storage systems have been introduced into the demand sides not only for saving energy and the global environment, but also for compensating voltage drops and supply interruption. In the future power systems, a lot of small-sized DGs will supply the electricity with existing large-scale generators under a competitive environment. In this context, it is desirable that DGs contribute to stable, reliable and economic operations by coordinating with existing large-scale generators. For example, power from large-scale generators could be leveled if DGs are operated during the peak period. Also, ancillary services such as frequency control, voltage control, and supply of reserve capacity could be executed by controlling DGs directly or indirectly. Under these circumstances, the authors have proposed a new power distribution system: Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS). This paper investigates some kinds of power supply systems which coordinate DGs with existing large-scale generators including the concept of FRIENDS and considering how DGs are managed. The effects of DGs which contribute to supply the energy and/or the reserve in every power system are evaluated.