Abstract:Compared with electromagnetic voltage transformer, capacitor voltage transformer commonly used in power system has many advantages, such as high shock resistance, low cost, low maintenance and workload cost, but there are still some common problems: the space occupied is large, the required insulation design level is high (directly in contact with high voltage), and insulation is easily failure in bad environment. In order to solve these problems, a non-contact capacitor-coupling voltage transformer suitable for 10 kV and below is designed. Based on the principle of electromagnetic induction, the coupling capacitance formed by the measuring end of voltage transformer and the inner core of cable, the transmission line or the wire inside the insulation sleeve are used as the high-voltage terminal capacitance, and the capacitance formed between the voltage transformer measuring end and the earth is used as the low-voltage terminal capacitance. Then the influence of voltage transformer capacitance on frequency characteristics is analyzed theoretically. The electric field and capacitance between the measurement end of coupling voltage transformer and high voltage transmission line is calculated and optimized by finite element simulation. Finally, the test is carried out on a single-phase 10 kV transmission cable. The results show that the designed transformer is capable of measuring the voltage accurately in real time, providing new methods and ideas for the establishment of intelligent power system, real-time online monitoring of power grid and field operation of relay protection.