Short-circuit Current and Current Protection Influence Analysis for Distribution Network with Distribution Generator Access Based on Short-circuit Ratio

An increase in the access proportion of distributed generations in the distribution network leads to great changes in the characteristics of short-circuit current, which impacts the accuracy of current protections. At present, the method of studying the influence of current protection with distributed generation access is mainly through the iterative algorithm. In this paper, it is found that the concept of short-circuit ratio can be introduced into the short-circuit current calculation in the grid with distributed generation access, and the short-circuit current can be estimated. In view of the complexity of the iterative algorithm used in current protection analysis, this paper proposes an approach based on short-circuit ratio to analyze the impact on current protection. Firstly, the concept of short circuit ratio based on specific fault point is introduced, and the meanings of short-circuit ratio are defined. Secondly, this study proposes a method based on short-circuit ratio to calculate short-circuit current, and its basic principle is analyzed and the specific application in short-circuit calculation of power grid is given. Then the protection evaluation based on short circuit ratio is proposed. Finally, take the 10kV typical network topology as an example to prove the feasibility of the method based on short-circuit ratio.