Analysis and Comparison of MSS and Fuzzy Methods for Optimal Capacitor Placement in Distorted Distribution Systems

Two algorithms for optimal capacitor sizing and placement in distorted distribution systems based on Maximum Sensitivities Selection (MSS) and fuzzy theory are presented and compared. Placement and sizing of fixed and switched capacitor banks under nonsinusoidal operating conditions is a constrained optimization problem with discrete variables. The objective function includes peak power and energy losses considering the cost of capacitor banks, while IEEE power quality limits and the number and locations of installed capacitors are used as constraints. A list of candidate buses are generated using the sensitivities of constraints and objective function with respect to reactive power injection at each bus. The best bus is selected by sequential placement of one capacitor unit at all candidate buses. In the fuzzy algorithm, a suitable fuzzy combination of objective and constraints is generated as a criterion to select the most suitable bus for capacitor placement. The a-cut process is used to guarantee simultaneous improvements of objective function and constrains. Simulation results for two IEEE distorted networks show the advantages and limitations of each method.

Keywords:

Harmonies , capacitor banks , placement , sizing , MSS , fuzzy theory