Voltage control of distribution networks using fuzzy approach and capacitors offline planning

This paper proposes a new approach to real time control of the bus voltages in the distribution systems. This approach consists of two control parts; includes offline and online control. In the offline part, switchable capacitors are scheduled based on day-ahead load forecasting. This step is solved using an efficient coding PSO algorithm. The under load tap changer (ULTC) is not a control variable in the offline scheduling and is only operated to improve voltage based on fuzzy approach. Once the switchable capacitors are scheduled, they are fixed on their hourly position in the real time operation. Then the ULTC is controlled based on the fuzzy system in the real time operation of the network. Easy implementation of the offline scheduling due to elimination of the ULTC as a control variable, removal of switching operation constraint and removal approximately of the voltage constraint is the main advantage of the proposed method. In addition, self-healing and possibility control of the bus voltages in different conditions such as unpredictable load changes and contingencies are other benefits. The 69 bus IEEE test system has been used to analyze and validation of the proposed approach.