Sensivity-based optimal capacitor placement on a radial distribution feeder

Optimal capacitor placement determines the size, type, and location of capacitors to be installed on a radial distribution feeder that will reduce peak power and energy losses while minimizing the costs of investment and installation of the capacitor banks. This paper describes a sensitivity-based optimal placement of capacitors that employs a new load characterization scheme using a voltage-current-angle-logger. The proposed method allows modeling of loads of different power factors for different portions of the distribution feeder. The optimal solution is obtained by testing various combinations of capacitor banks (based on the smallest bank size specified by the user) and candidate nodes along the distribution feeder, and calculating the resultant savings. In order to reduce solution time, the candidate nodes are ranked according to their sensitivity factors. The highest ranking nodes are considered first in the optimization process. At a node where the placement of a capacitor yields the greatest savings, a fixed capacitor bank is assigned. The procedure is terminated when the maximum allowable number of capacitor banks have been placed or until no savings improvement can be found. Based on the results of the placement of fixed capacitor banks for different loading levels, the switching capacitor banks can be determined. The proposed method has been applied to a typical distribution feeder of a local electric utility. Computer simulation results are very promising and they indicate that the proposed method yields large annual savings.