Application of Fuzzy Logic Technique for Power Loss Reduction in the Nigeria 330kv System

Abstract of Application of Fuzzy Logic Technique for Power Loss Reduction in the Nigeria 330kv System

To improve the overall efficiency of the power system, the performance of transmission system must be improved. Some of the vital ways of achieving this objective is by reducing power losses in the system and also improving voltage profile. An important method of controlling bus voltage is by shunt capacitor banks in the transmission substations. The capacitor absorbs reactive power flow in the system, thus improving power factor. When this is done, active power is also improved. In this work, a 10-bus transmission system is taken as model. Newton-Raphson’s power flow program is executed using MATLAB toolbox to obtain p. u nodal voltage ranging from 0.8890 to 1.0564, total real power line losses (0.09438 p.u), and total reactive power line losses (0.36970 p. u). By using power loss reduction, power loss index is evaluated and normalized in the range [0, 1]. These indices, together with the p. u nodal voltage magnitude, is fed as inputs to the Fuzzy Inference System to obtain Capacitor Suitability Index (CSI). The CSIs obtained, ranges from 0.244 to 0.897. The values of the CSIs determine nodes most suitable for capacitor installation. Experimentally, highest values of CSIs are chosen for capacitor installation. As a result, 3 buses (3, 8, and 10) with CSI values of 0.680, 0.750, and 0.897 respectively, are chosen. Capacitor sizes of 50MVar, 85MVar, and 60MVar (obtained from Index Based Method) are installed on the buses. Voltage profile improves by 3.74%, 3.27%, and 3.33% respectively, while total real power loss in the system reduces by 17.55% and total reactive power injection to the network reduces by 8.70% respectively. Overall, system stability and efficiency, hence, reliability, are improved by installation of capacitors at suitable locations in a transmission system.

Chapter One of Application of Fuzzy Logic Technique for Power Loss Reduction in the Nigeria 330kv System

INTRODUCTION

Background of Study

Electrical energy is generated at power stations which are usually located far away from load centres [1]. Thus, a network of conductors between the power stations and the consumers is required in order to harness the power generated. This network of conductors may be divided into two main components, namely, the transmission system and the distribution system [1]. As power flows in the lines, a significant amount is lost. Accurate knowledge of these power losses on transmission lines and their minimization is a critical component for efficient flow of power in an electrical network. Power losses result in lower power availability to final consumers. Hence, adequate measures need to be taken to reduce power losses to the barest minimum.

Power plants’ planning in a way to meet the power network load demand is one of the most important and essential issues in power systems. Since transmission lines connect generating plants and substations in power network, the analysis, computation and reduction of transmission losses in these networks are of great concern to scientists and engineers.

Studies have indicated that as much as 9% or more of total power generated is consumed as

losses at the transmission level [2]. The losses can be separated to active and reactive component of branch current, where the losses produced by reactive current can be reduced by the installation of shunt capacitors. Capacitors (capacitor banks) are widely used in transmission systems to reduce energy and peak demand losses, release the MVA capacities of transmission apparatus and to maintain a voltage profile within permissible limits [3]. The objective of optimal capacitor placement problem is to determine the size, type, and location of capacitors to be installed on the transmission network to achieve positive economic response.