Analysis of Series Magnetic Connection Characteristics in Preventive Test of UHV Rheological Exchange

The UHV DC transmission project is an important way of trans-regional large-capacity power transmission in China, and it is of great significance to shorten the measurement time of DC resistance of grid-side and valve-side windings and accurately grasp the demagnetization state of the iron core in the course of preventive testing of converter transformers, which is of great significance to the lean maintenance of converter stations in terms of reducing the time of pre-testing and improving the success rate of one-time power delivery. The article focuses on calculating the transition process of the test current of the angularly connected converter transformer group under the auxiliary magnetic wiring, comparing and demonstrating the feasibility of synchronous measurement of the windings on both sides of a single unit, and analyzing the demagnetization method under the same wiring and the testing method of the on-load tap-changer operating characteristics. The analysis results show that the synchronous measurement of DC resistance of the net-side winding and valve-side winding can be realized by using series magnetizing wiring with heteronymous connection, and finally the core demagnetization can be completed by using a lower current. The research content of this paper has a high reference value for reducing the amount of field work and improving the degree of integration and automation of the test device.