| Optimization of the reactive power in power system is an effective means to guarantee the economic operation and high voltage quality. Improved approaches based on Tabu search algorithm are investigated and the corresponding application software is programmed.As for the problem of reactive power optimization at a certain instant, an improved Tabu search algorithm is suggested. The index considering both losses reduction and high voltage quality is established. The constraints include voltage requirements, electrical limitations of apparatus and control restrictions. The transformer taps, capacitor capacity and generator terminal voltage are used as the control variables. The solution vector is decimal coded. An expanding neighborhood searching approach is used to escape from the local optimal solution.Based on Tabu search algorithm, an improved reactive power optimization within a day using the load forecasting results is presented. The solution is composed of the beginning time and the control variable of each time-interval. It can avoid the problem of twice optimization process, in which, the time-intervals are optimized at first and the reactive power is optimized based on each time-interval. So, the proposed method has the performance of optimizing the reactive power and time intervals simultaneously. In the cases of the neighborhood solutions falling into infeasible area, i.e., the voltage constraints are not satisfied, the index is switched to the voltage quality, so as to guarantee the searching process can work and gradually reach the feasible area. Once neighborhood solutions returning to feasible area, the index is switched back to losses reduction during the whole day.The application software based on above approaches are realized on the platform of VC++6.0, which has been used in the SCADA systems. IEEE4 system, IEEE14 system and IEEE30 system are used as test examples. The results of testing show that the proposed approaches and the application software are feasible.
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