Two-stage voltage transformer superposition principle based measuring circuit and operating method thereof

Abstract

The invention discloses a two-stage voltage transformer superposition principle based measuring circuit and an operating method thereof, relates to the field of high-accuracy voltage transformer voltage coefficient measurement and particularly provides a voltage transformer voltage coefficient measuring circuit and an operating method thereof. The measuring circuit comprises a tested two-stage voltage transformer T1, a semi-insulating two-stage voltage transformer T2, an all-insulating two-stage voltage transformer T3, a comparison device and the like, the T1, the T2 and the T3 are identical in rated transformation ratio and voltage, primary and secondary windings of the T2 and the T3 are serially connected, the tested two-stage voltage transformer T1 is subjected to error comparative measurement with the T2 and the T3 and serially connected windings thereof sequentially according to a superposition principle, and a voltage coefficient of the tested two-stage voltage transformer T1 isobtained by calculation. Influences on series connection addition measuring circuit due to low proportional linearity and imperfect shielding of two voltage transformers in series connection in voltage transformer series connection addition self-calibration are overcome, and uncertainty of voltage transformer voltage coefficient measurement based on the two-stage voltage transformer superpositionprinciple reaches 10<-6> level.

Description

technical field [0001] The invention relates to the field of measuring the voltage coefficient of a high-precision standard voltage transformer, in particular to a measurement circuit based on the superposition principle of a double-stage voltage transformer and a working method thereof. Background technique [0002] In order to ensure the fair trade of electric energy, the measurement transformers at the power supply and consumption gateways need regular metrological verification. Therefore, the accurate value of the standard voltage transformer is of great significance to the fair trade of electric energy, the accurate measurement of power equipment and line loss. For example, the typical value of the power factor of a large-capacity air-core reactor is 0.001 to 0.004. If the traceability of the loss measurement error is to be less than 1%, the accuracy of the voltage ratio standard needs to be higher than 0.001%. In 2014, China Institute of Metrology developed a set of 1...

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Problems solved by technology

[0014] In order to solve the above technical problems, the present invention provides a voltage coefficient measurement circuit based on the superposition principle of double-stage voltage transformers and its working method, which overcomes the problem of two voltage transformers connected in series in the self-calibration of the existing single-stage voltage transformer series addition. The impact of imperfect shielding of transformers and low proportional linearity on the series addition line makes the measurement uncertainty of the voltage coefficient of voltage transformers based on the principle of double-stage voltage transformer series addition superposition reach 10 -6 magnitude

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