Application Of Time Series Analysis In Reactive Power Optimization Of Power Systems

Reactive power optimization is an important aspect of maintaining the power systemoperated stability, economicly and safty. In recent years, with the continuously development ofChinese industrial system and the increasing electricity demands for production and living ofresidents, the scale of the network expansion rate increases and the structure of power systemnetwork becomes more and more complex, the reactive power optimization has great meaningin all aspects.To confine the action times of control devices, a voltage-reactive power optimizationintegrated system of centralized optimization and distributed control is designed. The systemincludes VQC（voltage and reactive power control system）and optimal power flow calculationat master station. By using the fractal theory，the original data in the range of nonperiodiccycles are divided into several time-intervals. After the processing, the optimal points areselected by optimal power flow calculation in each period. Based on the load fluctuation rate,the voltage/reactive power limits of nine–area figure are set in every period. As the loadfluctuation rates changed in every segment, voltage/reactive power limits are different. Andthe tap changers and switchable capacitor banks are regulated according to each upper andlower limit. Furthermore, correctness and effectiveness of the proposed method have beenvalidated. And the results show that it not only reduces power losses but also restricts numbersof control device.According to the example analysis, the simulation results prove that the centralizedoptimization and distributed control can reasonably optimize the power system, the integratedsystem also can ensure the voltage qualified and reactive power balance. The time divisiontheory which is presented in this paper can meet the limitation of control devices, iteffectively reduces the times of control action and prolongs the service life of the devices. Onthe other hand, based on the load fluctuation rate, the regulation of compensation limits caneffectively avoid the misoperation.