Abstract
At present, most sensor calibration methods are off-line calibration, which not only makes them time-consuming and laborious, but also causes considerable economic losses. Therefore, in this study, an online calibration method of current sensors is proposed to address the abovementioned issues. The principle and framework of online calibration are introduced. One of the calibration indexes is angular difference. In order to accurately verify it, data acquisition must be precisely synchronized. Therefore, a precise synchronous acquisition system based on GPS timing is proposed. The influence of ionosphere on the accuracy of GPS signal is analyzed and a new method for measuring the inherent delay of GPS receiver is proposed. The synchronous acquisition performance of the system is verified by inter-channel synchronization experiment, and the results show that the synchronization of the system is accurate. Lastly, we apply our online calibration method to the current sensor; the experimental results show that the angular difference and ratio difference meet the requirements of the national standard and the accuracy of the online calibration system can be achieved to 0.2 class, demonstrating the effectiveness of the proposed online calibration method.
Highlights
Any equipment or device that is used to perform measurements should be regularly calibrated
Offline verification is performed under line power failure conditions, which makes the operation complicated, and affects users in the area served by the sensor, which could lead to considerable economic losses and inconvenience
Our experimental results indicate that the sensor that is calibrated meets the national standard for ratio and angular differences, and can operate in a normal manner after calibration
Summary
Any equipment or device that is used to perform measurements should be regularly calibrated. As an important equipment in power systems, a current sensor should be periodically verified to ensure the stability of its current sensor operation as well as the accuracy of its output. This is because a current sensor contains components whose performance can degrade over time, including optical and electronic components, and is often placed outdoors for long time periods [1]. Accuracy and stability of current sensors are important guarantees for measurement, protection, and monitoring of power systems. Research on online verification technologies for current sensors is significant
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