| With the development of distributed generation and increasing distributed generation capacity into grid, the impact of distributed generation bringing to grid can’t be ignored. This article studies the impact to grid protection after a large number of distributed power accessed to grid. Its’ essence lies in that the access of distributed generation changes the structure of the original network and causes changes in the detection current of the protection, the ultimate impacts protection correct action.First, from a theoretical point of the thesis analyzes the distributed power access location, capacity, protection setting influence on the line, knowing that the greater the impact on the protection of distributed power capacity is greater, based on the theoretical analysis, built on IEEE7node system PSCAD/EMTDC transient simulation software platform to verify the theoretical analysis and calculation of the access capacity under different circumstances distributed power access points, the results confirm the theoretical analysis is consistent with the simulation to verify the theoretical analysis correctness and reliability.Based on the analysis of various impact on the distribution network, this thesis proposes an adaptive protection scheme based on local information content. By adding an adaptive protection to the original line protect can largely improve the sensitivity of circuit protection, it tries to adapt to changes of various lines working state. The simulation shows that the algorithm can well cope with the over flow of distributed power access to the grid, verifies the validity and correctness of the adaptive algorithm presented.Against the inadequate of the current protection, after analyzing the impact on distance protection with distributed power, the thesis proposes adaptive distance protection scheme. It mainly improves the tuning of section II of the protection distance, and makes simulation to verify the feasibility of the program. |
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