Reactive Power Optimization Considering The Cost Control

Reactive power optimization is an important topic for research of power system. The main purpose of it is not only to maintain the system's voltage level, but also to improve the voltage stability and reduce the system's active power loss by adjusting control variables such as generator's terminal voltage, transformer's tapping point and compensated capacity of the shunt capacitor which can make a reasonable distribution of reactive power flow.It is usually considered that the system's active power loss is minimum or voltage quality is best in traditional reactive power optimization models, which were feasible in the period when power plants and power network are united. But along with deeply innovation of the electricity market, bidding for access is implemented, and then power plants and power network are separated to independent entities. In the electricity market environment, each market entity runs independent economic accounting so that the cost and benefit are most concerned. Auxiliary services are no longer provided free by power plants, that means grid companies must pay for the active and reactive power needed by system. Thus, more reasonable optimization methods should be sought to coordinate the interests of different market entities since the traditional optimization model no longer meets the electricity market's demands.In this paper, a model considering the cost control which takes account of both the active power loss and the purchase cost of active and reactive power is proposed based on general optimization model considering minimum active power loss. Both needs of the two sides get a relative balance in the model, so as to make the best comprehensive economic benefit of the grid. It is a optimization model proposed for the electricity market as well as based on reactive power ancillary services. Therefore, several typical electricity markets and pricing methods of reactive power are introduced as preparation. Then, the model considering the cost control is educed and factors involved into the model such as active power marginal price, active power generating cost, reactive power generating cost and compensated capacity cost of the shunt capacitor are elaborated.Several kinds of reactive power optimization algorithms such as quadratic programming, genetic algorithm, and particle swarm algorithm are introduced in the paper. Simple comparative analysis is made for all common sorts of traditional optimization algorithm as well as artificially intelligent algorithm. Finally, algorithm flow used in this paper is presented. In the end, validated analysis for the proposed optimization model is made on the platform of MATLAB. IEEE-30 and IEEE-14 standard node system are optimized with the proposed objective function and the results are presented. Furthermore, comparison of the results obtained by the proposed model in the paper with that by the minimum active power loss model is put forward to verify the feasibility and superiority of the optimization model proposed in the paper.