On-line monitoring technology for the insulation condition of capacitive-type substation equipment

An on-line monitoring system for the insulation condition of capacitive-type equipment is described. The system adopts a distributed and layered multi-CPU structure, which is composed of the on-site measuring and processing unit, and data management and diagnosis system in the control room of substation. The on-site measuring and processing unit is based on DSP+FPGA hardware platform. Thus, the hardware design is simplified, the system is easy to be modified and updated, and the reliability is also raised. The windows and interpolation algorithm is applied to effectively reduce the influence of asynchronous sampling caused by frequency fluctuation of power system and to increase the precision. Moreover, many anti-jamming and protection methods are used in hardware and software design for the on-site intense electromagnetic field. Based on the simulation test conducted in the laboratory, the experimental results prove that measurement accuracy of the online monitoring system, which can meet the demand of on-site measurement.