Study On Distributed Energy Resource Based Uninterrupted Power Substation Control System

Recent deregulation in the electric power markets and increasing environmental concern have accelerated the improvement of various types small generations,such as a fuel cell, a wind farm power generation,superconducting magnetic energy storage,etc. The use of wide area T&D systems to interconnect a large number of generators and loads provides tremendous benefits in the cost and reliability of electricity supply. This apporach takes full advantage of load diversification, allows for minimal spinning reserve and favor use of the most cost-effective generators. Therefore, a powerful econocim and reliability incentive exists to interconnect DG with the utility T&D system rather than operate as local islanded systems. This holds true even for DG installations that never export power back into the T&D system.In the future, a number of small generators, which are generally called distributed generators, will be introduced in a distribution system.Leading the burgeoning power generation technology and new types of energy storage technology such as wind energy system, fuel cell, hydrogen production based energy storage and superconducting magnetic energy storage, to traditional power substation, a concept of the uninterrupted power substation is put forward which can make the power output of substation smooth, stable and uninterrupted. The models of three typical distributed electrical sources are first individually derived and examined. Successively these models have been adapted in view of their reciprocal integraion into an power substation. A coordinated management of thethree distributed sources is suggested in order to fully exploit the renewable energy from the wind.Because various types of DGs are to be independently controlled by their owners, the large-scale introduction of DGs makes system operation complex. The uncontrollable DGs such as a wind power generation system may enlarge the load fluctuation of the distributed system, causing some difficulties of the voltage control of the distribution system and the load frequency control of the whole system. However, if the controllable DGs such as fuel cells and superconducting magnetic energy storage are operated to compensate the output fluctuation of renewable power sources as well as load fluctuation, the reliability of distribution system will be improved.Therefore, a new operation scheme of a distribution system with the large-scale introduction of DGs is required. This paper focus on the load leveling by DGs as one of new technical advantages over the conventional system and propose a new control scheme of DGs for this purpose. Starting from the versatile interface model of distributed power network, the model of uninterrupted power station is presented and the mechanism of power coordination within the substation is analyzed. The concept of multi-agent technology, the hierarchical structure of the agents and the interaction strategy among the agents are described. On this basis a multi-agent system based coordinated control system for uninterrupted power station is built and the direction of further research are prospected.In order to value the proposed controle scheme, a simulation is carried out. As a result, load fluctuation of the whole uninterrupted power substation were effectively, suppressed.