Fault Analysis in Grids with Multiple Polyphase Buses

Abstract

This paper presents a method for fault analysis in power grids with multiple polyphase buses. Fault analysis for grids with multiple polyphase buses is performed by calculating an equivalent circuit for the polyphase bus of interest. Each equivalent circuit comprises an NxN impedance matrix, N corresponding to the number of phases of the polyphase bus for which the equivalent circuit is calculated. The elements of the impedance matrix are determined based on the voltages produced by the multiple experimental current injection vectors and the factorized pre-fault admittance matrix. The pre-fault admittance matrix represents the nodal admittance of an unfaulted multiphase bus. For each multiphase bus and fault type of interest, a fault current injection vector is determined based on the equivalent circuit determined for that multiphase bus. For each multiphase bus and fault type of interest, a fault voltage vector is determined based on the factorized pre-fault admittance matrix and the determined fault current injection vector for that multiphase bus and fault type.

Description

technical field [0001] The present application relates to power grids, and more particularly to fault analysis for power grids. Background technique [0002] A distribution management system (DMS) for electric power distribution systems uses a system model of the distribution network and assumed fault location, type, and fault impedance to identify faults by pattern matching between measured and predicted fault currents Location. Conventional symmetrical component based methods are not suitable for power distribution systems that are unbalanced both in construction and operation. A phase-based approach is required for accurate analysis. However, the resulting system can still be large even for moderate feeders due to the large number of nodes created by the explicit representation of individual phases. Impedance-based methods are both memory-intensive and time-consuming. Admittance matrix based methods are much more memory efficient, but time consuming. Compensation-bas...

AI Technical Summary

Problems solved by technology

However these conventional methods are computationally intensive for repeated fault analysis at many busbar locations with various fault types and involve constructing and factoring the admittance matrix, or even for each fault location and fault type the admittance matrix seek inversion

Traditional methods using symmetric components can also handle unbalanced faults, but cannot handle unbalanced network modeling

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