Optimal placement, sizing and dispatch of battery energy storage system integrated distributed generation

Abstract

Distributed Generation (DG) has become a key component in modern power industry due its significant advantages over the traditional power generation methods. Nevertheless, it is required to integrate them for distribution networks in such a way that their best expected outcomes can be achieved as inappropriate allocation may impose power system stability, protection and quality issues. This thesis presents novel analytical approaches for optimizing the DG location, size and power dispatch. Analytical methodologies based on formulating objective functions using loss and voltage sensitivities are presented for optimizing the DG location and size. An alternative method for determining the optimal DG sizes which is solved by Lagrange Multiplier Method (LMM) is also presented for better comparison. Moreover, the values obtained for optimal DG sizes from the novel analytical methods are compared with the results obtained by Genetic Algorithm (GA). A novel approach for determining the Battery Energy Storage System (BESS) capacities is presented as a part of developing an optimal power dispatch schedule for BESS units. The time varying nature of loads and DG output are also taken into consideration in this approach. Raw data obtained from a Solar Photovoltaic (SPV) farm in Hambantota area and typical three load profile data (i.e. mix load, residential load and commercial load) obtained from Long Term Generation Expansion Plan (LTGEP) of Ceylon Electricity Board (CEB) are used for modelling the SPV generation and load patterns respectively. The BESS capacities are determined in terms of Load Proportionality Factor (LPF), State of Charge limits (SOC) of battery storages and proportion of off-peak solar period energy consumption expected to be served by each BESS unit. An optimal BESS dispatch algorithm is also presented in this thesis for minimizing the energy losses and voltage deviations. The applicability of the proposed methodologies are tested using standard IEEE-6 and IEEE-33 test bus systems. Simulation results obtained for active power loss variations, voltage profile variations, SOC variations of BESS units and charging/discharging rates of BESS units suggest the acceptability and the appropriateness of the proposed methodologies.