Fault analysis in four-wire distribution networks

Abstract

The neutral wire in most existing power flow and fault analysis software is usually merged into phase wires using Kron's reduction method. In some applications such as fault analysis, fault location, power quality studies, safety analysis, loss analysis, etc., knowledge of the neutral wire and ground currents and voltages could be of particular interest. In this paper, a general short circuit analysis algorithm for three-phase four-wire distribution networks, based on the hybrid compensation method, is presented. In this novel use of the technique, the neutral wire and assumed ground conductor are explicitly represented. A generalized fault analysis method is applied on the distribution network for conditions with and without embedded generation. Results obtained from several case studies on medium and low voltage test networks, with unbalanced loads, for isolated and multi-grounded neutral scenarios, are presented and discussed. Simulation results show the effects of neutrals and system grounding on the operation of the distribution feeders.

A New Method to Monitor the Primary Neutral Integrity in Multi-Grounded Neutral Systems

“…The subscript (k) is omitted for simplicity in Equation (8). The positive root of Z lad is the equivalent impedance of the ladder network; thus, Equation (9) is derived.…”

“…However, in this method, the multiple grounding electrodes were represented by only one node. Other research about the MGN system mainly focuses on the power flow analysis or ground fault analysis [7][8][9][10][11], and the research on the broken neutral integrity monitoring is relatively little. Some researchers have proposed the method of measuring the primary neutral impedance, such as "fall of potential"-based methods [12] and "staged fault"-based methods.…”

Unsymmetrical short-circuit analysis for distribution system considering loads

“…This was attributed to the unbalanced nature of distribution system which can have single and two phase lines, unbalanced loads and untransposed feeders leading to unbalanced impedance matrix [4]. As distribution systems are generally unbalanced in nature; therefore fault analysis methods based on phase variable approach [5][6][7][8][9][10][11][12][13][14][15][16][17][18] give better results. In [5,6], a method based on triangular factorization of the admittance matrix is proposed to simulate different types of fault.…”

Multiphase unbalanced power flow and fault analysis of distribution networks with high penetration of inverter-interfaced DERs

“…New methods for power flow and fault analysis have been proposed in literature [1][2][3][4][5][6][7]. [3][4][5] propose solutions based on actual three-phase equations; however, system matrices are constructed in such way that power injection from DERs cannot be included.…”

“…[3][4][5] propose solutions based on actual three-phase equations; however, system matrices are constructed in such way that power injection from DERs cannot be included. More advanced methods with the ability of considering DERs have been introduced in [1,6] but they are all valid for radial or, at most, weakly meshed networks.…”