There is increasing interest in renewable energy sources interconnections in distribution systems since they are inexhaustible and nonpolluting. Wind and photovoltaic are among most mature renewable energy sources, and their penetration continues to increase. This paper proposes a method for distribution network reconfiguration to minimize annual energy losses by determining the optimal configuration for each season of the year. Uncertainties including the daily time varying load and stochastic power generation of renewable distributed generators (DGs) are modeled and taken into account. The method is based on generating a probabilistic generation-load model that combines all possible operating conditions of the renewable DGs with their probabilities of occurrence, then accommodating this model in the reconfiguration problem. The reconfiguration problem, based on Genetic Algorithm, aims at achieving minimum annual energy losses. The constraints include the voltage limits, line current limits, radial topology, and feeding of all loads. The proposed method has been tested on two systems. Simulation results show significant reductions in the seasonal and annual energy losses for all the studied cases.

This paper presents a simple and efficient reconfiguration approach for balanced and unbalanced radial distribution networks with Distributed Generators. The proposed approach starts with meshed networks by closing all tie switches. A switching index is defined for reconfiguration using apparent power flow in lines. The radial configuration was restored by opening one switch in each loop subjected to system operational constraints. The switching index can be used for both loss reduction and service restoration during normal and emergency situations respectively. The time varying nature of loads through using daily load profiles was considered. The results concluded the effectiveness of: (i) fixed configuration compared to hourly reconfiguration in terms of energy losses and number of switching operations during normal operation; and (ii) building restoration plans with the consideration of load variation compared to plans based on pre-fault or peak load values. The proposed method has been tested on one balanced and one unbalanced systems

Effect of load variation on network reconfiguration and service restoration plans in balanced and unbalanced distribution systems is studied. Comprehensive survey of the conceptual aspect as well as published algorithms for distribution network reconfiguration is presented. Different reconfiguration networks and scenarios are discussed. Results showed the effectiveness of building restoration plans with the consideration of load variation compared to plans based on pre-fault or peak load values.

Until now, distribution systems have radial structure with unidirectional power flows and a simple protection scheme. As one of the smart grid objectives and in order to face the continuous demand growth, there is a trend to connect more distributed generation (DG units) to distribution networks. In order to realize this aim and to increase the maximum loadability, meshed network architecture has been suggested. For this reason, in this paper three possible arrangements for distribution networks (i.e., base radial configuration, radial configuration obtained from a reconfiguration problem, and meshed network) have been investigated and compared with each other. The three network configurations are compared in terms of feeder losses, maximum loadability, voltage profile and maximum DG penetration level. The comparison has been tested on the 33 bus balanced and 19 bus unbalanced systems

This article presents laboratory scale models developed to study the per- formance of grounding systems in uniform soil. Two parallel grids are investigated and correlated with a same mass grid having the same conductormaterial and extend- ing over the same area at a depth equal to that of the upper grid. The experimental results demonstrate how the potential profiles and ground resistance are influenced by the grounding grid design such as number of meshes, grid depth and spacing between parallel grids. The effectiveness of the two parallel grids is compared with that of the upper grid only. The measured surface potential and ground resistance agreed satisfactorily with the present calculated values

This article presents laboratory scale models developed to study the per- formance of grounding systems in uniform soil. Two parallel grids are investigated and correlated with a same mass grid having the same conductormaterial and extend- ing over the same area at a depth equal to that of the upper grid. The experimental results demonstrate how the potential profiles and ground resistance are influenced by the grounding grid design such as number of meshes, grid depth and spacing between parallel grids. The effectiveness of the two parallel grids is compared with that of the upper grid only. The measured surface potential and ground resistance agreed satisfactorily with the present calculated values

This article presents laboratory scale models developed to study the per- formance of grounding systems in uniform soil. Two parallel grids are investigated and correlated with a same mass grid having the same conductormaterial and extend- ing over the same area at a depth equal to that of the upper grid. The experimental results demonstrate how the potential profiles and ground resistance are influenced by the grounding grid design such as number of meshes, grid depth and spacing between parallel grids. The effectiveness of the two parallel grids is compared with that of the upper grid only. The measured surface potential and ground resistance agreed satisfactorily with the present calculated values

This article presents laboratory scale models developed to study the per- formance of grounding systems in uniform soil. Two parallel grids are investigated and correlated with a same mass grid having the same conductormaterial and extend- ing over the same area at a depth equal to that of the upper grid. The experimental results demonstrate how the potential profiles and ground resistance are influenced by the grounding grid design such as number of meshes, grid depth and spacing between parallel grids. The effectiveness of the two parallel grids is compared with that of the upper grid only. The measured surface potential and ground resistance agreed satisfactorily with the present calculated values

In this paper, the element incidence matrix has been extended to develop a comprehensive three-phase distribution system power flow program for radial topology. Three-phase overhead or underground primary feeders and double-phase or single-phase line sections near the end of the feeder laterals have been considered. Unbalanced loads with different types including constant power, constant current and constant impedance are modeled at the system buses. Substation voltage regulator (SVR) consisting of three single phase units connected in wye or two single-phase units connected in open delta are modeled to satisfy the desired voltage level along the feeder. The mathematical model of distributed generation (DG) connected as PQ and PV buses are integrated into the power flow program to simulate the penetration of DGs in the distribution systems. The proposed method has been tested and compared with different IEEE test feeders result. The developed algorithm has been used to study the impact of both SVR and high penetration of DG on voltage profile and system power losses.

In this paper, the element incidence matrix has been extended to develop a comprehensive three-phase distribution system power flow program for radial topology. Three-phase overhead or underground primary feeders and double-phase or single-phase line sections near the end of the feeder laterals have been considered. Unbalanced loads with different types including constant power, constant current and constant impedance are modeled at the system buses. Substation voltage regulator (SVR) consisting of three single phase units connected in wye or two single-phase units connected in open delta are modeled to satisfy the desired voltage level along the feeder. The mathematical model of distributed generation (DG) connected as PQ and PV buses are integrated into the power flow program to simulate the penetration of DGs in the distribution systems. The proposed method has been tested and compared with different IEEE test feeders result. The developed algorithm has been used to study the impact of both SVR and high penetration of DG on voltage profile and system power losses.