Analysis Of Error Characteristics Of Electronic Voltage Transformer With Partial Resistance

The accuracy of electronic voltage transformer is related to the accuracy of electric energy measurement in power system and the safe and stable operation of protective equipment.According to the difference of measuring elements,the electronic voltage transformer can be divided into capacitance divider type,resistance divider type and resistance capacitance divider type.In this paper,we mainly studied resistance divider type.It has the advantages of small size and almost no energy absorption from the power grid.Due to the immature technology,there are many problems in the operation of electronic voltage transformers,especially the accuracy problem.At present,there is little research on the factors that affect the measurement accuracy of Resistance Voltage Divider Electronic Voltage Transformers(R-EVT)at home and abroad.Because of this,we established the model of R-EVT resistance voltage divider,draws the relation diagram of voltage amplitude error,phase Angle error and stray capacitance with Matlab software,and analyzed the influence of stray capacitance and other factors on the error characteristics.We introduced two calculation methods of stray capacitance under the simple model and the complex model,and presents the method of using Ansoft software to establish the finite element model of R-EVT to calculate the voltage ratio difference and phase error.The correctness of the algorithm is verified by comparing the calculated value with the actual value.We also analyzed the influence of phase-to-phase interference on the error.In this paper,the R-EVT is optimized both on the primary side and secondary side.Ansoft Maxwell software was used to simulate the electric field distribution cloud diagram of R-EVT before and after the application of shielding cover,and the comparison proved that the internal electric field of R-EVT could be optimized by applying shielding cover.In this paper,we taken the inhomogeneity of field intensity as objective function,using Ansys software with first-order optimization algorithm to optimize parameters of shielded enclosure,and then use Matlab genetic algorithm called Ansys APDL to optimize parameters of shielded enclosure,the parameters of the shield are further optimized,and the inhomogeneity of the field intensity of the two optimization designs is greatly reduced compared with the initial design.The voltage ratio difference and phase error of voltage divider are compensated by phase-shifting circuit and phase-in-phase proportional amplifier circuit at the secondary side,and the compensation effect is simulated by Multisim software.The measures proposed to reduce R-EVT error have certain significance for improving the accuracy of electronic voltage transformers.