For compensating reactive power, shunt capacitors are often installed in electrical distribution networks. Consequently, in such systems, power loss reduces, voltage profile improves and feeder capacity releases. However, finding optimal size and location of capacitors in distribution networks is a complex combinatorial optimisation problem.
Therefore, the optimal locations and sizes of capacitors in distribution systems can be formulated as a constrained optimisation problem. To solve this problem, the optimisation techniques are applied. Many optimisation techniques were applied to solve the optimal capacitor placement problem.
One of the other important advantages of capacitor placement in distribution network is to free up the capacity of feeders and related equipment, delaying or eliminating investment costs for improving or developing the system, and to free up the distribution transformers capacity.
The results showed that there is a voltage drop problem at the end of the system in the 10-bus system, and this voltage drop can be improved by capacitor placement. In addition, network losses can be reduced. In the 33-bus system, network loss reduction and voltage profile improvement can be seen.
The optimal capacitor placement is defined by determination of the number, location, type and size of the capacitors installed in the radial distribution network. In such problem, different objective functions may be defined.
Using capacitors has positive effects on networks such as power and energy loss reduction, voltage deviation and network harmonic reduction as well as improvement in network power factor. Capacitor placement is applied on the network in a form of single or multi-objective problems.