Test Device of UHV Transformer’s AC Withstand Voltage and Partial Discharge (PD) Tests

Abstract: This paper summarizes research status of test device of UHV transformer’s AC withstand voltage and PD test; Referring to 1000kV transformer test data from UHV test base of Wuhan High Voltage Research Institute, testing method and test circuit are proposed, which are applied in AC withstand voltage test and PD test on UHV device. Design methods of variable frequency power source and high-voltage reactor in the device are discussed. The paper also proves the rationality of test device and test method by analyzing the data from AC withstand voltage and PD test on 750kV transformer, and also demonstrates that test device has high stability, good security, strong practicability and good potential in application.   

Key words:  UHV transformer, AC withstand voltage, PD, power transformer    

Introduction

With rapid growth of electric load, it is urgent to increase super-high and UHV grid for long and high-capacity power transmission. In the ultra-high system, electric equipment is its core part. Smooth transmission of electric energy relies on reliable operation of electric equipment. The production department of electric equipment carries out strict delivery test when they leave factory. Because of large volume, equipment must be disassembled to small units, transported to site and then assembled on site. Therefore, it is very important to conduct the test on site. On the one hand, it needs to check whether the equipment is correctly installed; on the other hand, it is vital to check whether the equipment is broken or damped during the transportation. AC withstand voltage and PD test of electric equipment is an effective method, which reflects insulation condition of electric equipment. AC withstand voltage test reflects withstand capacity and voltage withstand level under normal condition; PD test is used for measuring PD level when electric equipment exceeds operation voltage and can correctly reflect health condition and aging degree.