Reliability Evaluation of Distribution System with Network Reconfiguration and Distributed Generations

Abstract

This chapter titled “Reliability Evaluation of Distribution System with Network Reconfiguration and Distributed Generations” proposes reliability and power loss evaluation of distribution system using network reconfiguration tool and optimal DG siting and sizing. The objectives are reliability improvement and power loss reduction subjected to various operating constraints. The renewable DG technologies including the synchronous machine-based biomass generator are considered in distribution system expansion planning. The network reconfiguration with DGs and tie-switch placement for the reliability improvement and loss minimization is proposed. Tie-switches are placed at terminal nodes with geographical constraints and their all possible binary combinations are considered. DGs sizing for the predefined DGs are calculated using integer programming for objective viz. reliability improvement and minimization of losses with penetration level taken for less than total load. Power loss is calculated using forward/backward sweep distribution load flow algorithm in all the cases analyzed. A search-based reconfiguration algorithm has been formulated for finding the optimal switch configuration for the radial distribution system with DG. The optimal DG placement and DG sizing for combined objectives of reliability improvement and loss minimization, using fuzzy logic approach is proposed in two steps. Out of four DG variables, type, and number are taken as fixed variables and size and location are considered as variables in the formulation. In the first step, for all DGs combination, their optimal sizes are calculated using nonlinear optimization tool with the improved reliability and real power loss reduction objectives. SAIDI and SAIFI indices are used for the reliability evaluation in this case. In the formulation three indices, power loss, SAIDI and SAIFI are used with weighing factors and taken as combined objective. A combined network reconfiguration and optimal DG siting and sizing is carried out for the objectives viz. real power loss reduction and reliability improvement for various penetration levels and various loading conditions. It is observed that optimal sitting and sizing of the DGs improve the system performance in terms of real power loss reduction and improvement in the system reliability. Different objectives give different optimal locations and sizes but based on the physical constraints, the final decisions are to be made. The present work may be a guideline to the planners and policy makers for planning the DGs in the distribution systems.