Combined approach for optimal placement and sizing capacitors in RDN

Purpose Reactive power in radial distribution networks (RDN) leads to detrimental effects like power factor degradation, voltage profile alterations and increased power losses, ultimately impacting network stability. This paper aims to present a novel two-phase optimization approach to address the challenging task of locating, sizing and determining the optimal number of capacitors in RDNs. Design/methodology/approach The first step of the proposed methodology is using a hybrid technique that combines the loss sensitivity factors (LSF) with voltage sensitivity factors (VSF) to identify network nodes requiring capacitor installation efficiently. The second step uses an external approximation technique to optimize the size and number of capacitors for each identified node, achieving significant power loss reductions. Findings The effectiveness of this new approach is evaluated on two RDNs: 33- and 69-bus. Simulations on these test systems demonstrate the effectiveness of the proposed approach, reducing total power loss by 34.7% in the first case and 35.3% in the second. The method’s robustness compared to other approaches further highlights its potential for practical implementation in RDNs, contributing to improved network stability and efficient power distribution. Originality/value This paper presents a novel, efficient and robust approach to determining the optimal number, location and size of an RDN capacitor. The problem is addressed through a new formulation with modified constraints. The method consists of two stages: initially, a hybrid LSF–VSF method identifies potential capacitor locations, followed by an external approximation-based mixed-integer nonlinear programming (MINLP) solver to optimize capacitor numbers and sizes. The proposed methodology is applied to the widely used 33-bus and 69-bus RDN test systems. Comparative analysis with existing methods highlights the proposed approach’s effectiveness. Key contributions of this study include the following: Proposes a new problem formulation with modified constraints. Proposes a novel two-stage framework for optimally locating and sizing capacitors in RDNs. Introduces a hybrid LSF–VSF algorithm to identify promising capacitor locations efficiently. Using an external approximation-based MINLP for optimal sizing. Demonstrates the effectiveness of the proposed approach through rigorous testing on standard benchmark systems. Provides a comprehensive comparative analysis against state-of-the-art methods, highlighting the proposed approach’s superior performance.