Long-term distribution network expansion planning incorporating distributed generations placement via improved harmony search algorithm

This paper presents a new multi-objective framework for long-term multi−stage Distribution Network Expansion Planning (DNEP) in which expansion options are augmentation and/or installation of substations, feeders and also Distributed Generations (DGs). The proposed framework takes into account investment cost, maintenance cost, operation cost and Expected Customer Interruption Cost (ECOST) in the optimization as four problem objectives, while considers operational restrictions, Kirchhoff’s laws, radial structure limitation, voltage limits and capital expenditure budget restriction as problem constraints. The proposed model is a non-convex optimization problem having a non-linear mixed-integer nature. Hence, a hybrid Improved Harmony Search Algorithm (IHSA) and Optimal Power Flow (OPF) is used followed by a Fuzzy Satisfying Method (FSM) to obtain the final optimal solution. The IHSA is a recently developed optimization algorithm which imitates the music improvisation process. In this process, the harmonists improvise their instrument pitches searching for the perfect state of harmony. The planning methodology has been demonstrated on the 27-node 13.8-kV test system in order to demonstrate the feasibility and capability of the proposed model. Simulation results illustrated the sufficiency and profitableness of the newly developed framework when compared with some studies addressed in common literature.