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Keywords

non‑contact; voltage transformer; frequency characteristics; finite element numerical simulation

Abstract

Compared with electromagnetic voltage transformer, capacitor voltage transformer commonly used in power system has many advantages, such as high impulse withstand strength, low production cost and low maintenance workload. However, some common problems that large space occupation, high insulation design level required (contact with high voltage directly), and insulation failure in severe environment are still exist in capacitor voltage transformer. In order to solve these problems, a non‑contact capacitor‑coupling voltage transformer suitable for 10 kV and below voltage level is designed in this paper. Based on electromagnetic induction principle, the coupling capacitors formed between the measuring end of voltage transformer and the inner core of cable, the transmission line or the wire inside the insulating bushing are designed as the high‑voltage terminal capacitance. The capacitor formed between the voltage transformer measuring end and the earth is acted 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, experimental test is carried out on a single‑phase 10 kV power transmission cable. The results show that the designed voltage transformer is capable of measuring the voltage accurately in real time, which can provide references for the establishment of intelligent power system, real‑time online monitoring of power grid and field operation of relay protection.

DOI

10.19781/j.issn.1673-9140.2023.03.022

First Page

197

Last Page

204

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