Study On Scheme Of Protection And Fault Location Of Distribution Network With Distributed Photovoltaic

With deterioration of the global climatope and increasingly lack of fossil fuel, more and more attention have been paid on distributed generation technology, represented as photovoltaic generation. As the enhancing of national polices, we can forsee that there will be more and more PV access to middle and low voltage distribution network in the future. PV will change network structure and power flow distribution. This may easily result in tripping missing or mal operation of traditional protection. This paper analyzed the impact of PV on protection of distribution network considering fault performance, then proposed an division protection scheme and confirmed its feasibility.Firstly, the running characteristic of PV grid-connected system was established. After introducing structure and working principle of each part of PV, the model of three-phase PV was built by the PSCAD/EMTDC simulation software. In the model, the PV grid-connected system was accessed to an infinite power system. The model’s MPPT and grid-connnected characteristic in condition of light intensity changing were analyzed by simulation. Secondly, a brief introduction about common network structure of distribution network and its protection configuration was proposed, including current protevtion, automatic re-closing devices and distribution automation based on FTU. Thirdly, the response characteristic of IIDG represent as PV was analyzed and the equivalent model of PV was built. Then the impact of PV on protection of distribution network was qualitative analyzed, and the relationship expression between short circuit current and capacity of PV when PV located in different position was emphasized discussed and built. Then the impact of PV with different capacity in specific access point was compared by an example. On that basis, the maximum penetration level of PV in specfic access point according to current protection’s state was obtained.Finally, a kind of zoning protection scheme for distribution network with PV was proposed. According to the principle of load must be equal to or less than the capacity of PV, the distribution network was divided into several sub-areas. With the help of distribution automation system, on-line monitoring and analyzing can be achieved. The principle and constitute of algorithm of fault area location was discussed emphatically, then the feasibility of this algorithm in condition of switching of PV or missing of fault information was analyzed and some improvement was made. The effectiveness of algorithm of fault area location and the modified algorithm was verified by an example of distribution network with33nodes.