Multi-grounded Distribution Systems Research Articles

A detailed network model for distribution systems with high penetration of renewable generation sources

One of the most important aspects that characterizes smart grids is the widespread integration of loads and renewable-based generators connected to the distribution network. In general, sequence or phase based network models have included the effect of ground return on equivalent phase and neutral impedances using the Kron's reduction and Carson equations. Under unbalanced grid operation, these traditional models can produce inexact results being inadequate for advanced grid analysis and optimization. This paper presents a detailed and compact formulation for the analysis of multi-grounded distribution systems. The key contribution of the paper is to introduce a detailed representation of the ground loops in the distribution system model suitable to be applied under different analysis methods as power flow, optimal power flow, state estimation and network pricing in an integrated manner. This contribution is meaningful since it allows to analyze future electrical systems with severe unbalanced operation due to high penetration of single-phase renewable and load sources. The ground parameters can be adjusted in the context of a state estimator that integrates ground voltages and currents. The proposed model is tested using illustrative and real-world large-scale test cases. Results reveal significant differences when compared with system analyses using standard three phase network model approach.

Analysis of Multigrounded Four-Wire Distribution Systems Considering the Neutral Grounding

This paper has explored the inherent characteristics of multi-grounded three-phase four-wire distribution systems under unbalanced situations. The exploration also involved the effects of neutrals and system grounding. Power engineers have often disregarded these effects while analyzing a power system. The simulation tool is PSpice for Windows. It is capable of representing and simulating the equivalent model with an explicit neutral wire and groundings of a multi-grounded distribution system. In this paper the equivalent model of a full-scale multi-grounded distribution system implemented by PSpice is introduced. Simulation results have illustrated the effects of neutrals and system grounding on the operation characteristics of multi-grounded four-wire distribution systems.

Analysis of multi-grounded four-wire distribution systems considering the neutral grounding

This paper has explored the inherent characteristics of multi-grounded three-phase four-wire distribution systems under unbalanced situations. The exploration also involved the effects of neutrals and system grounding. Power engineers have often disregarded these effects while analyzing a power system. The simulation tool is PSpice for Windows. It is capable of representing and simulating the equivalent model with an explicit neutral wire and groundings of a multi-grounded distribution system. In this paper the equivalent model of a full-scale multi-grounded distribution system implemented by PSpice is introduced. Simulation results have illustrated the effects of neutrals and system grounding on the operation characteristics of multi-grounded four-wire distribution systems.

Determining temporary overvoltage levels for application of metal oxide surge arresters on multigrounded distribution systems

Different analytical methods that may be used to calculate values of temporary overvoltage on multigrounded distribution systems as a result of single line-to-ground faults are evaluated in terms of their general accuracy; their ability to account for changes of earth resistivity, ground electrode resistances, and grounding frequency; and the overall impact of such changes on the calculated overvoltage level. Recommendations are provided for the use of these methods under different sets of system conditions. It has been concluded that the commonly used method based on symmetrical components is inadequate for anything but the simplest calculation for a system with near-ideal grounding parameters. For systems where poor grounding conditions are known to prevail, the best method of analysis is to neglect the ground effects altogether. The best overall results are provided by a sophisticated, matrix-algebra-based method which analyzes the ladder network cells of the multigrounded distribution neutral individually.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Detection of High Impedance Faults on Multi-Grounded Primary Distribution Systems

Three techniques for detecting high impedance ground faults on multi-grounded distribution systems are considered on a theoretical basis. The methods, based on (a) combining two current measurements, (b) detecting power frequency harmonics and (c) sensing sequence voltages, all appear to have promise but require experimental investigation to determine practicality.