An accurate continuous calibration system for high voltage current transformer

Tong, Yue; Li, Bin Hong

doi:10.1063/1.3523341

Cited by 12 publications

(8 citation statements)

References 4 publications

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“…Its magnitude and phase responses are closer to the ideal integrator when the sampling frequency is two times higher than the signal frequency. 16 The two clamp-shape coils were compared with a calibrator which is made up of an accurate digitizing voltmeter (HP3458A) and a shunt. The uncertainty of the calibrator is 0.013% for ratio error and 0.4 for phase error.…”

Section: Verification Of the Simulationmentioning

confidence: 99%

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An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

Zhou

2013

Review of Scientific Instruments

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Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Based on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class.

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Section: Verification Of the Simulationmentioning

confidence: 99%

“…However, its accuracy is sensitive to the air gap length. [13][14][15][16] Tong et al 16 propose a continuous calibration method which can be operated when the power line is energized. However, it has some shortages: (1) a clamp-shape air-core coil is used as the standard current transformer, whose accuracy is sensitive to the air gap.…”

Section: Introductionmentioning

confidence: 99%

An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

Zhou

2013

Review of Scientific Instruments

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“…In a previous study [8], the open Rogowski coil CT was used as the reference CT; however, the air gap of the Rogowski coil affected its accuracy. Even if the printed circuit boards printed circuit board manufacturing process is adopted, the size of the open air gap must be less than 0.1 mm to achieve an accuracy of 0.05 [9].…”

Section: Introductionmentioning

confidence: 99%

Passive‐compensation clamp‐on two‐stage current transformer for online calibration

Xiong

et al. 2021

IET Science Measure & Tech

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Digital measurement equipment such as electronic transformers enable real-time functional control and monitoring systems to be built in power grids to accommodate the large-scale access of distributed renewable energy to the grid. However, the current offline calibration of electronic transformers is difficult to implement; therefore, an online calibration method for electronic transformers must be developed to ensure their accuracy. The design of a clamp-on two-stage current transformer (CTS-CT) with a passive compensation loop is presented herein. The compensation loop is utilised to reduce both the amplitude and phase errors, thereby achieving high accuracy. The formulas for calculating the resistance and capacitance of the passive compensation loop are presented. The expanded uncertainties (95% confidence level) of the proposed CTS-CT are estimated to be lower 0.03% for the amplitude error and 1′ for the phase error. Experimental results indicate that the proposed CTS-CT prototype is not affected by the external magnetic field nor the opening and closing times, thereby enabling good-quality online calibration for field applications. Moreover, the proposed CTS-CT adopts neither an active compensatory circuit nor software compensation; therefore, the manufacturing of the CTS-CT is steady and simple, and the calibration procedures are simplified.

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“…With the development of the smart grid, the digital substations are widely constructed as an important component of the smart grid. At present, there are two structures with which to gather the primary side signal of power lines in the digital substation [1][2][3]: the first is using an electronic transformer which is controlled by a synchronous sampling clock to measure the current and voltage from the primary side. And then converting the sampling values to IEC 61850-9-2 packets, for further controlling, protection, monitoring and metering [4][5]; the second is using an analog merging unit (MU) to gather the signal from the traditional transformer [6], and then converting the sampling values to IEC 61850-9-2 packets.…”

Section: Introductionmentioning

confidence: 99%

A multi-function IEC 61850 packet generator based on FPGA

Wei

Cheng

2016

Meas. Sci. Technol.

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An IEC 61850 packet generator is used to produce IEC 61850-9-2 packets by simulating the merging unit and testing the IEC 61850 digital device. While the existing IEC packet generator can produce ideal digital without any noise, it does not take into account the fact that the merging unit output signal packets will be inevitably superimposed with noise. Since the International Electrical Commission standard of the electronic current transformer specifies the minimum output signal-to-noise ratio of the merging unit to be 30 dB, and the signal superimposed with noise will influence the operation performance of the digital device, it is necessary to design a multi-function IEC 61850-9-2 packet generator for a digital device test. Therefore, in this paper, a multi-function IEC 61850 packet generator has been developed, which not only can output various IEC 61850-9-2 packets, but also can add white Gaussian noise to the signal for digital device testing. By testing three digital electricity meters from different manufacturers, we showed that the error of the digital electricity meter is significantly larger when the signal packet is superimposed with noise. Also when the signal-to-noise ration is 30 dB, the error of one of the meters exceeds the allowed range of the accuracy class. This indicates that the noise testing and the noise setting function of the system has an important role in the testing of a digital device.

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An accurate continuous calibration system for high voltage current transformer

Cited by 12 publications

References 4 publications

An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

Passive‐compensation clamp‐on two‐stage current transformer for online calibration

A multi-function IEC 61850 packet generator based on FPGA

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