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Huo G.-Y.,Harbin Institute of Technology | Zhang G.-Q.,Harbin Institute of Technology | Yu W.-B.,Harbin Institute of Technology | Guo Z.-Z.,Harbin Institute of Technology | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

This paper researches the common signal extraction of optical voltage transducer and the imbalance during the transmission of dual optical path, gives an introduction to the basic principle of optical voltage transducer based on electro-optic Pockels effect, and analyses the main source of noise in the system and the difficulty in extracting the weak signal and the system error resulted from the imbalance of dual optical path. Furthermore, instead of applying the mature DC modulation, it offers a method to improve SNR by AC modulation and additionally works out the simulation block diagram. Then considering the differences in the dual optical path which are imbalanced, it offers the idea of low-frequency processing and high-frequency balancing. The result of simulation proves that using this method can improve the output SNR of optical voltage transducer to some extent.

Cheng S.,Harbin Institute of Technology | Zhang G.,Harbin Institute of Technology | Yu W.,Harbin Institute of Technology | Shen Y.,Harbin Institute of Technology | And 4 more authors.
Conference Proceedings - 2012 IEEE 7th International Power Electronics and Motion Control Conference - ECCE Asia, IPEMC 2012 | Year: 2012

The all-fiber optical current transformer (A-FOCT) is based on the Faraday magnetic rotation effect for current measurement, and utilize closed-loop digital control which is to adapt the demand of future smart grid development. In this paper, the origin of linear birefringence in sensing coil was analyzed. The effect of linear birefringence on the measurement system error was investigated. The mathematical model was established, based on which, the simulation was performed to discuss the correlation among the sensing coil sizes, linear birefringence and fiber optical materials, and the size of sensing coil was optimized. © 2012 IEEE.

Wang J.,Harbin Institute of Technology | Guo Z.,Harbin Institute of Technology | Zhang G.,Harbin Institute of Technology | Wang G.,Beijing Xuji Power Optics Technology Co. | And 2 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

The basic structure and working principle of ECVT (Electronic Voltage Transformer based on Capacitive voltage divider) are presented. Its transient characteristics are analyzed and the basic characteristic of single-phase 220 kV ECVT is taken as the modeling parameter. OrCAD software is used to simulate its transient response and quantify its range of resistance. Simulative result indicates that the short circuit and reclose problem occurred during the transition process of ECVT can be solved by properly setting the voltage divider resistance. Experimental data confirms that, the transient characteristics of 220 kV ECVT are the best when the resistance is set at 10 MΩ class, which, according to IEC60044-7, meets the design requirements for measuring accuracy of 0.5 class and for protection accuracy of grade 3P.

Yu W.,Harbin Institute of Technology | Jiang B.,Sichuan Electric Power Research Institute | Zhang G.,Harbin Institute of Technology | Zhang G.,Beijing Xuji Power Optics Technology Co. | Guo Z.,Beijing Xuji Power Optics Technology Co.
APAP 2011 - Proceedings: 2011 International Conference on Advanced Power System Automation and Protection | Year: 2011

Before becoming qualified engineering application product, and realizing large-scale engineering application target smart substation, electronic current transformer (ECT) must first accept comprehensive and strict performance tests. The sand-glass test scheme of ECT is proposed. This test scheme includes thirty-three test contents, combining with the type tests, the special tests and the field tests. These tests not only provide reliable guarantee for electronic current transformers running safety and quality in smart grid, and establish the valuable basis for forming the standard and test methods of ECT. The developed optical current transformers have passed the above complete and strict product tests. The optical current transformers are large-scale used in 220kV smart substation in Liaoning Province. It is the first smart substation all using optical current transformer in china. The substation includes ninety-nine optical current transformers. Test and operation results show that the optical current transformers have satisfactory measurement accuracy and operation reliability. The steady-state measurement accuracy of optical current transformer excels IEC 0.2S level measurement requirements, and the transient measurement accuracy excels IEC 5TPE level protection requirements. © 2011 IEEE.

Yu W.,Harbin Institute of Technology | Jiang B.,Sichuan Electric Power Research Institute | Zhang G.,Harbin Institute of Technology | Wang G.,Beijing Xuji Power Optics Technology Co. | And 3 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

The site operational performances of optical current transformer are evaluated in error calibration, energy measurement statistics and metering system overall calibration. The error calibration data before and during site operation show the error change is less than 0.1%, satisfying the requirement of class 0.2S. Two independent measuring systems are established for the long-term comparison of site operational data to demonstrate the long-term operating stability of digital energy metering system under various environmental conditions. The overall calibration data of digital energy metering system indicate that, at rated power, the uncertainty is 9.0×10 -5, the confidence probability is 97.15% and the system comprehensive error is 1.013%, satisfying the requirements of codes.

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