Research On Technologies Of Fiber Optical Current Transformer Key State On-line Monitoring

In the actual operation process of fiber optical current transformer(FOCT),system error increase or function failure will happened by the effect of extern al environment changing or internal device performance degradation.The changes above are slow process that can be early warned by monitoring the FOCT internal key state parameters(such as ambient temperature,SLD operating states,half-wave voltage of phase modulator,the received optical power of photodetector,etc.).In this paper,the design scheme of FOCT key state on-line monitoring system is proposed with the hardware circuit and algorithm.Further,a FOCT key state on-line monitoring system is developed,which was tested on China electric power research institute’s testing platform of full work conditions and long term performance of electronic transformer as trial operation for one year.The influence of the key state parameters on the system performance is analyzed through data analysis of trial operation with theoretical calculation and experimental design.It is found that the main factor affected system error is environmental temperature and the direct cause affected system reliability is the input optical power of photodetector.In order to improve the accuracy and reliability of FOCT,it is necessary to compensate for the temperature and give timely warning to the attenuation of optical power.The research above provides a theoretical basis and data support for the improvement of FOCT design,it will be helpful to improve the reliability and accuracy of FOCT in the field operation.