The Research Of UHV Wide Variable Ratio Standard Voltage Transformer

Voltage transformer is the key equipment of AC power plant.It connects the primary system and secondary system of power grid to provide signals for measurement,measurement and relay protection devices.Its accuracy is related to the accuracy of electric energy measurement and the reliability of relay protection.In ACUHV system,the accuracy of 1000 kV capacitive voltage transformer is the focus of attention of all parties.Standard voltage transformer is a standard device used to evaluate the accuracy of voltage transformer.Therefore,it is of great significance to carry out routine test and on-site accuracy verification of UHV transformer in UHV substation by using UHV standard voltage transformer.The traditional 1000 kV standard voltage transformer mostly adopts cascade structure,which has the disadvantages of complex structure,large weight and large error affected by the site environment.In order to meet the accuracy requirement,UHV standard voltage transformer has a narrow range of conversion ratio.The lifting mechanism of UHV standard voltage transformer used in the field has large maintenance workload and unsatisfactory operation convenience.In view of the above problems,this paper analyses the standard voltage transformers with different structures and principles,determines the technical route of UHV wide variable ratio standard voltage transformer,and develops UHV wide variable ratio standard voltage transformer with rated primary voltage covering 110 kV to 1000kV.In order to reduce the influence of external electromagnetic field on the accuracy of equipment,the single-stage winding structure is adopted.In order to meet the different working conditions of field and laboratory,the chassis and lifting mechanism are redesigned and manufactured.Finite element analysis and optimization of the electric field in the key parts of the product are carried out to make the theoretical field strength conform to the design benchmark.Based on the experience of design and manufacture of standard voltage transformer,the production process of UHV wide variable ratio standard voltage transformer is established in this paper.In the production process,the key processes were strictly controlled,and the prototype was finally manufactured.Through error test and adjustment,the measured error of 1000 kV UHV wide variable ratio standard voltage transformer at 110 kV voltage level conforms to 0.05 level,and the measured error at 220 kV to 1000 kV voltage level conforms to 0.02 level.The final error performance,insulation performance,sealing performance and lifting performance of the product achieve the design goal.The UHV wide variable ratio standard voltage transformer has high accuracy and good linearity,which is in line with the current development trend of the power industry,and can also promote the improvement of the manufacturing level of measuring equipment in China.