Abstract
Optical voltage transformers (OVTs) have been applied in power systems. When performing accuracy performance tests of OVTs large differences exist between the electromagnetic environment and the temperature variation in the laboratory and on-site. Therefore, OVTs may display different error characteristics under different conditions. In this paper, OVT prototypes with typical structures were selected to be tested for the error characteristics with the same testing equipment and testing method. The basic accuracy, the additional error caused by temperature and the adjacent phase in the laboratory, the accuracy in the field off-line, and the real-time monitoring error during on-line operation were tested. The error characteristics under the three conditions—laboratory, in the field off-line and during on-site operation—were compared and analyzed. The results showed that the effect of the transportation process, electromagnetic environment and the adjacent phase on the accuracy of OVTs could be ignored for level 0.2, but the error characteristics of OVTs are dependent on the environmental temperature and are sensitive to the temperature gradient. The temperature characteristics during on-line operation were significantly superior to those observed in the laboratory.
Highlights
Optical Voltage Transformers (OVTs) based on the linear electro-optic effect and applied at a certain scale around the world are recognized as a current development trend in the power transformer sector because of their simpler insulation structure, greater security and anti-electromagnetic interference properties [1,2,3]
In order to ensure the comparability of data, the testing method and the testing equipment in output of a traditional voltage transformer was compared as standard data with the same testing the laboratory were exactly the same as those used in the off-line field tests
After the Optical voltage transformers (OVTs) prototypes were calibrated for the first time, no output of a traditional voltage transformer was compared as standard data with the same testing adjustment or compensation for error were done during the experiments
Summary
Optical Voltage Transformers (OVTs) based on the linear electro-optic effect and applied at a certain scale around the world are recognized as a current development trend in the power transformer sector because of their simpler insulation structure, greater security and anti-electromagnetic interference properties [1,2,3]. The testing of OVTs based on the above research on temperature characteristics was conducted in the laboratory. The accuracy test is usually performed only for a single OVT under laboratory test conditions, whereas three-phase transformers run synchronously in field operation, where the existence of the adjacent phase may cause additional errors [14]. We selected OVT prototypes from a company of which multiple OVT products have already been put into operation, and tested the error characteristics under the three conditions of the laboratory, off-line in the field and during on-line operation. The comparison and analysis for the error characteristics of OVT under the three conditions of laboratory, off-line in the field and during on-line operation, are expected to help promote the application of OVTs
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