Study On Online Monitoring System For Power System Overvoltage

Overvoltage is a critical factor of that influence the security of the power system. It is due necessary to online monitoring overvoltage in power system as obtaining the waveform and characteristic parameters of overvoltage, which is very helpful in anasys accident and improve the insulation cooperation. Most of the existing overvoltage monitoring systems adopt divider to get signal. But for the reasons of the divider's self-deficiencies, its application under higher voltage grade is limited. Aimed to solve this problem, in this paper, the key technologies of overvoltage online monitoring system are researched systematically and a method that using a special designed voltage transducer which is installed at the tap of bushing to get the voltage signal from the power grid is presented.Also a new type of overvoltage monitoring system model machine based on this method is developed.This paper, first, briefly introduces the structure of the whole system and its operational principle. And then, structure and parameters setting of the voltage transducer fixed at the tap of bushing aer presented in detail.The author also gives the design principle of the key companent and analysis factors which influence the transducer's characteristic. The validity of transducer model is testifies through the experiment in lab.The paper detailedly introduces the primary principles and concrete method of overvoltage online monitorning data acquisition system,particularly discusses the scheme and the function of the second divider circuir,signal transformation circuit,trigger circuit and protection unit controlling circuit.Moreover,it briefly illustrates the operational principle of data acquisition card and the structure of system acquisition software.The paper accomplishes the adjustment and test to the whole overvoltage online monitoring system and gives the overvoltage waveform character analysis base on the operation result of monitoring system which has been set in power system and operated for more than one year. Based on these analysis and support vector machine, a new algorithm is proposed to identify the internal and external overvoltage.The result indicate that this overvoltage monitoring system operates reliable and can satisfy the requirements of overvoltage monitoring in power grid.