An Optimized Overcurrent Protection Study Using Enough Number of SFCL at Optimal Points of a Distributed Real City Grid

In this paper, a new approach to an optimized overcurrent protection in a distributed real city grid is presented. A superconducting fault current limiter (SFCL) can be used for solving overcurrent problems. The most important overcurrent problem in the grid are the short circuit currents, especially in high voltage lines. Therefore, many devices connected to the grid could be damaged. In spite of the protection advantages of the SFCLs, using them for all connection nodes of the grid is an expensive and complicated solution. If the optimal points of the grid to use the SFCL are decided, the most appropriate number of SFCL can be used. A 2.026 MW powered distributed real city grid application is realized in Sincan providence in Ankara City. Also, the distribution line is 0.4 kV and the transmission line is 34.5 kV. Besides, the distributed grid is fed by two generators and two renewable energy sources which are a wind turbine and a solar power plant. Electricity consuming parts of the grid are greenhouses, loads and electrical transmission/distribution/customer lines. In order to analyse the grid, two options are simulated. Firstly, any resistive type superconducting fault current limiters (RSFCL) have been used for short-circuit protection. Results of the first option are not acceptable according to overcurrent standards. The second option is that RSFCLs are used at the optimal points of the grid. Optimal nodes are founded by the genetic algorithm. When the RSFCL is positioned at the determined optimal points, the fault current in some busbars has been obtained 82.78% less.