Study And Development Of Generator On-line Partial Discharge Monitoring System

The development and application of on-line monitoring system is the indispensable approach for transition from the traditional time-based maintenance methodology to a condition-based maintenance strategy. Generator is a pivotal equipment of electric system, and its stator winding, which is always exposed to heat, electric, ambient, mechanical stress during operation, is a relatively fragile part. Nowadays, measurement of Partial Discharge is worldwide recognized as an effective method to monitor the insulation condition of stator winding, and related technology has flourished in past decades.In this paper, the mechanism and characterizing method of Partial Discharge (PD) is briefly introduced, the development history and classification of PD monitoring techniques is illustrated and an on-line Partial Discharge monitoring system based on B/S structure is described.The waveform and amplitude spectrum of raw PD signal and its transfer characteristics in cable, stator bar and the whole winding is studied, and sequentially the monitoring frequency band in which the whole winding can be monitored and corresponding sensor are selected.The hardware part based on unified Data Acquisition & Monitoring Platform is studied in this paper, including signal conditioning & acquisition, input protection and trigger signal generating circuits.The software flow and algorithm of data process is studied, with quasi-integration as emphasis. The influence of integration parameters on pulse resolution and calculation of apparent charge is studied via simulations; finally the suited parameters are selected for generator PD monitoring and implemented in FPGA.The build and mechanism of PD test specimen, the PD pattern captured by system described in this paper is studied and the influences on pattern of integration parameters are studied as well.