Method for eliminating measurement error of transformer by active impedance vector electric voltage synthesis

Abstract

The invention discloses a method for eliminating transformer measurement errors by active impedance vector voltage resultant. The method is to detect a current of a primary circuit of a secondary winding and a current of a detection winding of a transformer independently and respectively, convert the currents into voltages, amplify the converted voltages, input the converted voltages to an add operation amplifier to sum the converted voltages and complete output of active impedance vector voltage resultant. The method can eliminate transformer measurement errors and improve measurement precision.

Description

technical field [0001] The method relates to a method for eliminating the measurement error of a double-stage current transformer in alternating current measurement. Background technique [0002] Current transformers are indispensable electrical components in power systems and metering and testing systems. This is because: a, low input impedance, b, good long-term stability and temperature characteristics, c, large current can be converted into small current measurement through impedance transformation. [0003] With the development of production and market needs, the requirements for accurate measurement of current transformers are getting higher and higher. There is an urgent need for instrument current transformers that measure currents ranging from hundreds of amperes to several milliamperes, with a measurement accuracy of 10PPm. Due to the characteristics of the transformer itself, in actual work, it will vary with the input current, secondary load and other parameter...

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Problems solved by technology

[0008] 1. With the design of zero magnetic flux, the working magnetic flux of the detection winding is in the critical area of ​​the initial magnetic permeability of the glass film alloy iron core, which makes the hysteresis phenomenon more serious

[0009] 2. The circuit is complex. Because there is a deep AC negative feedback loop between magnetoelectricity, it is easy to generate high-frequency self-excitation and phase shift, and the parameters of the circuit are not easy to choose

[0010] 3. The DC current drift is difficult to eliminate because there is no negative feedback loop, and the performance of the glass film alloy core will be deteriorated due to the influence of DC

[0011] 4. Due to the influence of mutual inductance and self-inductance, there is a reflection impedance problem in the electronic negative feedback of the compensation winding, which may cause false balance-zero magnetic flux in the detection winding, but the ampere-turn of the primary and secondary windings is not balanced

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