A Proposed Algorithm for Reactive Power & Voltage Coordination in Distribution Systems Using Fuzzy Technique


This method finds the Under Load Tap Changer (ULTC) position andcapacitor ON/OFF status of each hour for the next day in main or secondarydistribution substations, so the secondary bus voltage improves and the reactivepower flow into the transformer can be restrained at the same time. The onlycondition to achieve these goals is the previous knowledge (by forecasting) ofload demand for active and reactive power and the primary bus voltage for eachhour of that day. The practical constraints are involved through the use ofmembership concept in fuzzy set theory, where these constraints are bus voltagelimits, the tolerable worst power factor & the maximum allowable number ofswitching operations for the Load Tap Changer (LTC) and capacitor in a day. Thismethod is also considering the variation of load active & reactive power with itsvoltage, where the loads are classified into three categories according to theirrelationship with voltage, and so there are constant impedance loads, constantcurrent loads and constant power loads. To demonstrate the usefulness of thismethod an example on one of the Iraqi national grid substations (132/33KVYarmook substation) was made in MATLAB.