Voltage And Reactive Power Coordinated Control Of Three Classes For Distribution Network

With rapid economic development, the power load is growing rapidly, power is ofshortage, and higher requirements are needed for keeping power supply reliability and quality.Distribution network is the last part of the power system, and power is supplied directly to theuser, which is most closely linked with the user. As the distribution network with a largeradius, with levels of transforming voltage, and with low level of automation, those oftenmake that the enduser’s voltage quality can not be guaranteed. It is necessary to controlvoltage and reactive power of the distribution network. The control of voltage and reactive ofdistribution network is an effective means to ensure safe and economic operation of powersystems, also are important measures to reduce network losses and improve voltage quality.This paper introduces and analyzes the latest status of voltage and reactive power controlof the distribution system, which pointes out the problems. Then this paper has a detailedanalysis on the reasons that causes the problem of low voltage of distribution network.Reactive power control works by changing the on-load tap transformer turns ratio, reactivepower compensation device switching capacity to achieve change in voltage, power factor andpower loss. Then this paper describes the traditional voltage and reactive power controlstrategy of substation based on nine-area diagram, and gives the mathematical model.The traditional distribution network reactive power control is generally achieved onlypartial optimization of voltage and reactive power, so it has certain limitations, prone toaccrue that substation’s bus of low voltage side is qualified, but distribution transformer isunable to adjust, while the user’s voltage still exceed the limited voltage. Distribution networkvoltage and reactive power coordination control of three levels algorithm is on the basis of thesubstation voltage and reactive power control strategy. The upper and lower limits of voltageand reactive power are determined according to the principles of substation’s the nine zonescontrol strategy, and the objective of voltage and reactive control is minimum voltage offsetof all global nodes. Coordination and control of voltage and reactive power of distribution network used real-time operating data of distribution network, that is, grid operationparameters and state of controllable variables and the margin. Adjust the various controllablevariables, and judges the effect of the regulation program on each node voltage, then calculateout the voltage offset, then select the scheme that meet the requirements of minimum voltageoffset. If the program number is more than one, then choose the best scheme by the principleof optimal power factor and minimum power loss.Finally, apply the algorithm to two real distribution networks, which obtains bettercontrol results and economic benefits, and improve the users’ voltage to the maximum extentand improve the power factor, and reduce the power loss at the same time.