چكيده به لاتين
Shunt capacitor banks can generate the reactive power and therefore it is not necessary to supply all reactive power demands and losses by the feeding substation in a sub-transmission network. Thus, there is a possibility to minimize the loss associated with the reactive power flow through sub-transmission system by optimal switching scheduling of capacitor banks in distribution substations.
In many cases the procedure for these capacitor banks operation is done by defining a threshold value usually equal to the reactive power of the capacitor bank per step. In other words, when the reactive power of load becomes larger than the threshold value (capacitor nominal capacity per step) the capacitor bank will be increased one step, and if it becomes lower than the threshold value the capacitor bank will be reduced manually.
Most of the time in a year, the demand is slightly lower than the threshold value (medium load level), so thus according to this procedure (traditionally used in utility) no change in capacitor banks will be applied, resulting in high losses in the sub-transmission network.
In fact, The most important issue in power system designing and operating is minimizing losses and costs. Unlike existing methods which use a large amount of data across the entire network to determine optimal dispatch of shunt capacitors, this thesis introduces a method for optimal switching of capacitors only by using local data including voltage and current magnitude, outgoing/incoming reactive powers, and reactive load of transformer. The scheduling is carried out for different parts of Alborz Province MV network in IRAN. Simulation results show an acceptable accuracy in optimal dispatch of capacitors. The proposed algorithm of this thesis which, if executed in each substation, calculates the optimal capacitor without the need to receive any other information from other substations and minimizes the total losses of the sub-transmission network.
