The Research And Development On An On-line Insulation Monitoring System Of Capacitive Equipment In High-voltage Substation

The reliability of power transmission has been becoming an important factor withthe increment of capacity and voltage level in power system. On-line monitoring forhigh voltage equipment is a crucial requirement for condition-based maintenancewhich has taken over conventionally preventive maintenance. It is significant that HVcapacitive equipment is conducted on-line insulation monitoring since it has thebiggest proportion in HV substations.Dielectric loss factor is the critical factor reflecting the insulating state of HVcapacitive equipment. Therefore, how to precisely on-line monitor it is becoming ahotspot in online monitoring of power system within the condition of dynamicallyelectromagnetic interference.DSP-based insulation monitoring system with multi-CPUs is proposed in thisthesis, which is based on the deeply analysis of insulation monitoring technique for HVcapacitive equipment. And hardware and software operating in lower position machinefor terminal examination system is designed in this thesis. Active zero magnetic fluxmicro-current sensor is designed in order to extract signal effectively. Hanning windowinterpolation algorithm is used to correct the error caused by frequency fluctuationduring phase-angle measurement. In order to compensate the error caused by phasechanges of reference signal, fusion algorithm based on synchronous detection isproposed. The developed system management and diagnostic software can realize thefunction of fault diagnosis analyses which is based on maintenance regulation in thePC software..Simulation results show that this system has high measurement accuracy, goodanti-disturbed performance and robustness. Therefore, it meets the requirement ofsystem design and has a good application prospect.