Optimal size and location of shunt capacitors on distribution feeders using the reduction of PPL and EL

Shunt capacitors are installed at primary feeders in electric power distribution systems to improve voltage profiles and the power factor as well as to reduce power losses generated by the flow of reactive power in the system. Furthermore, increasing the capacity of the distribution system by released KVA is another objective. Reducing peak power and energy losses, improving the power factor and keeping the voltage profile within the maximum and minimum permissible range (+/- 10% of the nominal voltage) providing that the voltage drop on the feeder is within the allowable value (5% of the voltage value) are investigated in this work. The benefits are achieved through the proper selection of capacitors by finding the optimal location and compensation levels as well as the maximum net dollar savings due to optimized shunt capacitor installation. The optimization technique used is based on an objective function that takes into account the maximum net dollar savings due to the reduction of peak power and energy losses while deducting the cost of the capacitor bank installation. The method is simple and does not require sophisticated optimization techniques. The optimal capacitor location and compensation level problem is solved using the Optimal Reduction of Peak Power and Energy Losses (ORPPL& EL). Practically, feeders and distributed loads are non-uniform and their models have to be converted to uniform using the base resistance technique. The reduction loss formula for determining the optimum location and compensation level of the capacitor banks considering an end-load on the uniform feeders is used. Analysis of optimal reduction of OPPL & EL is carried out for three different values of fixed end load reactive current using one to five capacitors. Results of optimal location and size of shunt capacitors, maximum net savings, improvements in voltage drop, power factor and released KVA are obtained and evaluated using a realistic test feeder system. The consequences of the changes in cost coefficients, the load growth and the installation of two capacitors on a realistic distribution feeder are studied and presented from an economical point of view to decide whether a relocation scheme is required or not.