Yucheng Distribution Network Partition Reactive Power Optimization And Control Research

The purpose of reactive power optimization is to change the reactive power flow distribution, and then reduces active power loss and improves voltage quality, though adjusting the control devices of reactive power in power system. There are usually on-load tap changer (OLTC) and shunt capacitor sets in substation of distribution network, so we can carry out reactive power optimization though the tap adjustment of OLTC and switching of capacitor sets.Considering the distributed characters of Yucheng distribution network, the dissertation presents a reactive power optimization algorithm basing distribution network partition. In this new algorithm, we use the partition thought for distribution network, and then divide a big distribution network system into several small subsystems. Although using traditional mature method, calculating in these small subsystems reduces the work time greatly.As for reactive power optimization at a single state, the objective function is to make the active power loss be least, and the requiring constraint includes two parts. The first part is nodal power balance equation constraint, and the second part is inequality constraint composed by branch power, nodal voltage, reactive compensation, and position of the OLTC taps. In the single state optimization, in order to reduce the active power loss and satisfy the voltage requirement of medium and low voltage network, we use the improved Genetic Algorithm to obtain the tap position of OLTC and switching number of capacitor set.As for comprehensive reactive power optimization during a long time, for example one day, we firstly use Artificial Neural Networks to forecast the power load in next24or48hours, and get the forecast data. According to the obtained data, the long time is divided into several small time durations. We still adopt the method for reactive power optimization at a single time to obtain the tap position of OLTC and switching number of capacitor set. This comprehensive optimization not only meets the voltage pass rate, but also reduces the action times of control devices, and extends the using time of these devices.The method using in this dissertation is proved be satisfied, and has good availability, though the calculation and operation of the Yucheng power grid.