| With the development of the national economy and improvement of people’sliving standard, the higher the reliability of power system is increasingly demanded.Insulation condition of high voltage equipment (HV equipment) is monitoredcontinuously via the on-line monitoring technique, genuine and accurate data aresupposed to provide great support for the status maintenance at the same time whichhas great significance on the safe operation of HV equipment. This paper is supportedby the cooperation project “Insulation On-line Monitoring System of the High VoltageEquipment based on WSN” of the Research Institute of Changchun Power SupplyCompany in Jilin province of STATE GRID Corporation of China and LejinElectronics Company Limited of Jilin province. The content of this paper is from theproject above, and some problems are discussed for further researches.A current sensor amplifier circuit is designed in this paper featuring very lowoperating voltage (only2.5V), low power consumption, single supply, fully protectionand seamless interface with ADC of the system resulting in achieving maximum ADperformance. These characteristics of the amplifier above make it particularly suitablefor battery-powered on-line monitoring devices. Precision and noise feature areanalyzed and assessed in this paper. Results show that the precision of the samplingpart can meet the design requirements and restore accurate signal, and is helpful toimprove the precision of the system.Comparison of properties of two kinds (active, passive) of commonly used zeroflux current sensors is made in details in this paper, and comparison of realadvantages and disadvantages of the two transformers is especially made from theactual engineering application point of view as well, proving there’s no big differencebetween them. The principle of transformers’ selection is put forward for the practicalproject. Some particular issues should be paid much attention to while designing thesystem using the passive sensor.A simulation experiment device based on DDS function signal generator inlaboratory is presented in this paper. Compared with the widely used high pressure simulation experiment device and low voltage simulation experimental apparatus, theexperimental device is more suitable for on-line insulation monitoring devicedebugging, that devices are based on harmonic analysis method. Several majordisadvantages of the traditional simulation experimental device have been overcomeby this device, such as the necessary use of expensive special capacitor, the influenceof power fluctuations, and the inability of harmonic simulation. This simulationdevice can simulate the harmonic and noise interference with controllable frequency,high stability, large continuous range of current and voltage phase and low cost. Thissimulator can not only simulate high voltage equipment, but also are suitable for thedebugging purpose of device based on harmonic analysis method, for it is easy tocontrol the experimental variables; meanwhile it is very helpful to analyze and assesscomprehensively the performance of the monitoring system.Variations of the parameters during the general process of the HV equipment’sinsulation deterioration are deduced in detail in this paper. Criterion given by themonitoring system of the HV equipment’s insulation deterioration should not besimply taken by certain physical quantities, should be judged by the dissipation factortan δ, the equipment’s capacitor C and the current I, and also by the tendency of thethree quantities above. This paper analyzes the original waveform data and finalresults of the measurement of the actual on-line monitoring device; compared with thedata under the laboratory conditions, there is greater harmonic interference in theon-site sampling waveform, but the result is hardly affected by the interference aboveand the system achieves all its precision. |
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