Equivalent three-phase short circuit calculation method based on static equivalence considering grounding branches

摘要

With the fast development of modern interconnected power systems, the impact of external neighboring network on internal network becomes ever-increasingly important and cannot be ignored in three-phase short circuit calculation. Static equivalent methods can retain the essential information of original external neighboring network. However, existing equivalent methods still have many insufficiencies. In this paper, a static equivalent model considering grounding branches of the external network is proposed to improve the equivalence accuracy of three-phase short circuit calculation. In this model, the equivalent grounding branches are derived according to the weighted partial derivatives of border node voltages with respect to the grounding branches. Based on the proposed equivalent model, a new equivalent three-phase short circuit calculation method is presented to achieve high calculation accuracy for interconnected power systems. The simulation results of the IEEE 14-bus system demonstrate the effectiveness and correctness of the proposed model and method.