Evaluation Method Of Schemes For Reactive Power Compensation In Transformer Area Considering Voltage And Economic Benefit

As the terminal part of the electric power system, it’s voltage distribution is very different from medium-voltage distribution network. Medium-voltage distribution network line loss voltage is small, the node voltage distribution curve is approximated by a smooth curve, the node voltage distribution curve of transformer area tends to show a sharp decline. The first and end node voltage deviation is often very large and it ofen exists problem of the lower and upper bounds of the voltage. Reactive power optimization is an effective method to improve the voltage and reduce the loss of the network, medium-voltage distribution network reactive power optimization is based on voltage eligibility at each node as the constraint conditions, different reactive power compensation scheme’s difference is not obvious in improving the voltage but is obvious in reducing the network loss, so the medium-voltage distribution network only need net loss or a single voltage index can identify the pros and cons of reactive power compensation. Transformer area is difficult to make all node voltage in the qualified range only relying on reactive power optimization, different reactive power compensation scheme’s effect is very complex in improving the voltage and reducing the network loss,the change of index value has no regulation.It is unable to comprehensively measure the pros and cons of reactive power compensation’s voltage and economic benefits only by installation voltage monitoring deviceor into the head of transformer area or network loss index. At present, there is a lack of effective index and method to quantify the of pros and cons of a variety of reactive power compensation schemes.So this paper reasearch on evaluation method of schemes for reactive power compensation in transformer area considering voltage characteristic and economic denefit.Firstly, set up the power flow simulation and reactive power optimization model in transformer area.Analysis of the voltage distribution’s difference between transformer area and distribution network and different reactive power compensation schemes’ s characteristic.Secondly, According to the evaluation of power system reactive power compensation schemes focuses on economic benefit level or voltage problem in transformer area, in this paper, the evaluation index system of reactive power compensation schemes is further improved from two aspects of voltage characteristic and economic benefit.Then, design improved order relation method to determe index weight. It can alculate the weight of the index by combination subjective and objective method.it takes into account the views of experts and considering the characteristics of the data itself.On this basis, grey relational grade method and technique for order preference by similarity to ideal solution is designed to evaluate the schemes of reactive power compensation. The two methods are applied to solve the multiple attribute decision-making Problems, but single method exits defect.The comination of the two methods can reflect the relationship of similarity of the data curve and the position between need evaluation solutions and ideal solution. Its evaluation result is a specific numerical value, which can be used to compare and rank of pros and cons between level similar objects.The reactive power compensation schemes’ selection of transformer area is a direct relation with the power supply enterprises and users, from the perspective of power supply enterprises as far as possible to save costs, from the perspective of the user side as far as possible to improve the quality of voltage, but it is difficult to meet the two sides at the same time. In this paper, evaluating model for the reactive power compensation schemes is established, which can carry out comprehensivly compare on reactive power compensation schemes which stress voltage or economic benefit. In order to provide somel reference for the practica application on the selection of reactive power compensation schemes giving consideration to the voltage and economic benefit.