Fast short circuit analysis method for unbalanced distribution systems

A fast short circuit analysis method for unbalanced distribution systems is proposed in the paper. Two matrices developed based on the topological structures of distribution systems are used to analyze the variations of bus voltages, bus current injections and branch currents under fault conditions. The proposed short circuit analysis method with exact three-phase models can then be developed from these two matrices and be exploited to solve the various types of single or simultaneous unsymmetrical faults. Since the proposed method does not use the traditional admittance matrix, the time-consuming procedures including matrix tri-factorization and/or matrix inverse are not necessary; therefore, the proposed method can achieve the advantages of high speed, robust convergence and accuracy. Test results show that the proposed method has great potential to be integrated into the existent distribution automation.