The Power System Stability Development and Application of Mathematical Model of Reactive Power Loss Index As A Measurement Of Voltage Stability in Nigerian Transmission System

Abstract

The Nigerian power system faces growing challenges in maintaining voltage stability due to increased demand, insufficient reactive power reserves, and the complexity of modern grid operations. This study presents the development and application of a mathematical model known as the Reactive Power Loss Index (RPLI) for identifying critical (weak) buses suitable for reactive power compensation in the Nigerian 52-bus transmission network. The RPLI model, derived using the bus admittance matrix method, serves as a voltage stability indicator by quantifying reactive power loss distribution across load buses. The model was implemented in MATLAB R2021a, and the voltage stability of the network was evaluated under contingency conditions. The performance of RPLI was compared with two existing methods: Relative Electrical Distance (RED) and Fast Voltage Stability Index (FVSI), based on voltage magnitude, maximum loadability, reactive power loss, and transmission line charges. Results showed that RPLI accurately identified vulnerable buses and achieved a reduction in reactive power loss by 6.78% and active power loss by 0.76% during contingencies compared to base contingency conditions. These outcomes validate the RPLI as an effective and computationally efficient tool for optimal placement of Static VAR Compensators (SVCs) and enhancing voltage stability in power systems.