The Research Of Distribution Network Protection Containing Distributed Generation

The distributed generation technology is helpful to promote renewable energy development, improve the environment and the competitiveness of green energy in power system. However, in the interconnection of distributed generation (DG), the traditional simple single-source radial-network has developed to complicated multi-source loop-network, bringing traditional relay protection act incorrectly, which deeply affects system operating and controlling. Therefore it is necessary to analyze the influence of the DG to the distribution network protection and propose its countermeasures, which has important practical significance for promoting the development of distributed generation.This paper introduces the concept, background, classification, and the grid method of DG. The different capacity and location of the DG have different impact on the current flowing through the feeder protection in distribution network, meanwhile using the simulation of PSCAD/EMTDC verifies the conclusions. According to the feature of distribution network, a MAS based scheme of three-tier aggregate protection is proposed. Combined multi-agent technology with the wide-area protection, the scheme adopts wide-area failure direction as the fault location based on the amount of information that can quickly determine the fault location, and isolate the fault. In the anti-islanding protection issues, optical fiber communication signal detection method is proposed and combined with IEEE1547and IEEE1741standard gives the grid criteria. Finally, relied on the IEC61850standard designs the communication scheme of the MAS based three-tier aggregate protection. Given the communication mode of substation and station. Through analysis of communication latency the communication scheme meets the requirements of relay protection.