Abstract
The on-site measurement of transient voltages is of great significance in analyzing the fault cause of power systems and optimizing the insulation coordination of power equipment. Conventional voltage transformers normally have a narrow bandwidth and are unable to accurately measure various transient voltages in power systems. In this paper, a wideband parallel resistive–capacitive voltage divider is developed, which can be used for online monitoring of transient voltages in a 220 kV power grid. The structures of the high-voltage and low-voltage arms were designed. The internal electric field distribution of the high-voltage arm was analyzed. The influence factors and improvement techniques of the upper frequency limit were studied. The parameters of the elements of the divider were determined. The voltage withstand performances and scale factors under lightning impulses and AC and DC voltages, the temperature stabilities of scale factors and the step response and bandwidth of the developed voltage divider were tested. The results show that the deviations of the scale factors under various voltage waveforms and different temperatures ranging from −20 to 40 °C are within 3%. The withstand voltage meets the relevant requirements specified in IEC60071-1-2011. The step response 10~90% rise time is approximately 29 ns, and the 3 dB bandwidth covers the range of DC to 10 MHz.
Highlights
Publisher’s Note: MDPI stays neutralPrecise measurement of transient voltage waveforms in power systems is of great significance to fault analysis, optimal insulation design, optimized high-voltage experiments, etc
Online monitoring of transient voltages can be achieved by a voltage transformer, bushing tap, optical electric field sensor, high-voltage divider, etc. [1,2,3,4,5]
In order to meet the demand of monitoring various transients in the outdoor environment, the divider developed in this paper is characterized by good resistance against the environment, high temperature stability and a strong broadband measurement
Summary
Precise measurement of transient voltage waveforms in power systems is of great significance to fault analysis, optimal insulation design, optimized high-voltage experiments, etc. In non-contact voltage division, the sensing electrode is more likely to be installed on the ground, in which the space capacitance between the conductor and sensing electrode is used as a high-voltage arm [22,23]. These non-contact voltage division techniques have the advantages of a low cost and easy application, the inter-phase coupling issue reduces their practicality. The development works include the structural design of high and low arms, analysis of the internal field distribution, a study on the upper cut-off frequency of the divider and its optimization and the determination of the components’ parameters. The response characteristics of the divider were tested by the step response method and frequency sweep method
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