Document Type : Research article


1 Department of Electrical Engineering, Payam Golpayegan Institute of Higher Education, Golpayegan, Iran.

2 Department of Electrical Engineering, Faculty of Engineering, Arak ‎university, Arak, Iran

3 Arak University


Most electrical devices like motors and transformers act as inductive loads, resulting in a lagging power factor and reduced system capacity and increased losses, ultimately decreasing voltage. To address this, parallel capacitors are installed which provide reactive power control, increase capacity, reduce losses, and lower distribution and transmission costs. The parallel capacitors provide the required reactive power, reducing apparent power losses. Adding parallel capacitors not only reduces losses but also improves the voltage profile, power factor, and voltage stability. Some recent methods to reduce distribution losses suggest adding optimal parallel capacitors at suitable locations. This study performed optimization of capacitor placement in a standard distribution network, with and without distributed generation (DG) and harmonic currents, using DigSILENT and MATLAB with a genetic algorithm. The goal was to minimize losses while meeting voltage and harmonic constraints. Results showed incorrect capacitor size or location selection can worsen voltage deviations with high harmonics. The method demonstrated optimal busbar capacitor selection and location. Examinations revealed more than 3-4 capacitors in the 33-bus system did not significantly impact results. Furthermore, using just one busbar capacitor did not satisfy voltage and harmonic constraints. In summary, optimally-sized and located parallel capacitors reduce losses, improve voltage profile and stability, and address issues with inductive loads. But with harmonics, suboptimal capacitor placement can worsen conditions. The optimization method successfully identified the best capacitor parameters for the test system.