A study of over-voltage monitoring device for different types based on virtual instrument and optical voltage sensor

A device has been developed for the on-line monitoring and the analyzing of the over-voltage of different types. It is based on the sensor head made with BGO crystal (Bi4Ge3O12) and the optical fiber that is the transmission medium of the optical signal to implement the conversion of the measured voltage. The acquisition unit of the system is composed of four A/D converters to fulfill the four channel lock-in acquisition at a high sampling rate. The sample frequency of the A/D is 20 MHz. The remote transmission of the acquisition information, and the remote control of the monitoring system are implemented by the virtual instrument through the data socket technology. The data processing of the over-voltage, including the calculation of the single over-voltage, the statistical analysis of the multiple record, probability distribution of the over-voltage and the identification of the type of the over-voltage through the fuzzy theory is implemented through LabVIEW platform. This device has better antiinterference characteristic, more rapid transient respond and perfect data analysis compared with other over-voltage monitoring devices composed of electromagnetic voltage transformer or capacitive voltage transformer. The analogy test results show that the system can realize the performance to monitor many different types of over-voltage.