Interruption reduction at substations using battery energy storage systems.

Abstract

Reliable electrical power supply is vital in the modern society and electrical distribution utilities are responsible for ensuring continuity of supply. South Africa is experiencing a rapid increase in electrical power demand; with the number of people requiring electrification growing continuously. Eskom’s capacity to generate excess electricity is completely used up as the currently installed transformers are of a certain fixed rating and cannot accommodate the rapid continuous growth, resulting in the utility not being able to meet the power demand. The concept of load shedding is utilized when supply cannot meet demand due to certain system constraints and demand reduction is required; it is also regarded as a last resort action taken to prevent the collapse of the power system and protect the current electrical power equipment connected to the system. The constraints are mainly due to the incapability to store the power at any point in the supply, traditionally electrical power generation plants typically produce more energy than necessary to ensure adequate power quality at the points of transmission and distribution as a large percentage of the energy is lost in the power station as waste heat and even more losses occur at the power lines when the generated is transmitted for use; thus raising a need to implement a system to save as much of the discarded energy in between the points of the life-cycle of electricity such as battery energy storage systems (BESS). BESS is useful for its prompt capacity to adjust power well as the characteristics of storage and supply capability. The utilization of BESS for the reduction of network power loss and management of network congestion is the key factor to realize the optimal operation of distribution networks as it can store excess power that can be later utilized when there’s a shortage in the system. In this dissertation, the integration of BESS into electrical Distribution systems is investigated, with the objective to reduce the power supply interruptions that occur at the substations (planned/unplanned) and know-how BESS can be used to improve the performance of a distribution system. The proposed methodology consists of two main parts. The first one is of design and simulation of a balanced substation; It’s important to ensure that the substation is operating within its specifications as a standalone before any external features are added to improve the already existing adequate performance. And separately, a BESS with a control method for State of Charge (SoC) for the battery considering the network power loss during both grid and off-grid operation to ensure smooth BESS operation without compromising the voltage regulation performance of the network; as the basis of the investigation, consecutively. The second part consists of integrating the two models (Substation & BESS) and conducting simulation studies to obtain unique scenario-based outcomes. The optimal placement of BESS is investigated as the efficiency of integrating it into large-scale distribution networks depends on it. The substation and BESS are modelled and simulated using MATLAB Simulink to verify the effectiveness of the proposed methodology and based on the research it is evident that BESS integrated distribution systems solutions to overcome shortage created by load shedding or any other interruptions (planned/unplanned) are the best way to go in maintaining continuity of supply to customers.