Homotopy-enhanced Short Circuit Calculation For General Distribution Networks With Distributed Generation: Algorithm And Application

Recently,renewable energy,such as wind energy and solar energy,is developing rapidly.Large-scale distributed generation in distribution networks has had a certain impact on power network running and scheduling.When short circuit fault occurs,there is a need to calculate the short circuits flowing through different equipment(such as transformer,line,and breaker).These values are used to confirm the specifications of devices and design specifications of grounded system.Thus provide a basis for electrical switchgear.Besides,short circuits are of great important for relay protection setting.Therefore,short circuit calculating is vital for distribution system analysis.In this paper,for different DG model,we apply compensation method for short circuit calculation.Different load model has different effect on the convergence and accuracy of short circuit calculation.When there are constant power load in power system,conventional short circuit calculation methods may encounter divergence.In this paper,we propose a three-stage homotopy-enhanced iteration compensation method to solve this problem.The accuracy is guaranteed,as well,the convergence property is improved.As more and more distributed generators access to distribution network,the short circuit current level rises,bringing great harms to power system equipment and power system protection.This paper proposes a two-stage technology of binary particle swam optimization algorithm based on loop searching method for distribution network reconfiguration to reduce the short circuit current level.Without increasing investment in equipment,the short circuit currents are reduced and the protection equipment can work correctly.IEEE-13 and IEEE-8500 node test cases are tested on to verify the proposed methods.The results show that the convergence property is improved and the results are accurate.Besides,a practical 1101 node test case is used to verify the feasibility and reliability of distribution reconfiguration for short circuit currents reduction.