Power System Over-voltage Monitoring And Research For Generator Security Forecasting

Abstract: Power system over-voltage is a subject closely in correlation with equipment insulation. Over-voltage condition suffering on equipments can indirectly inflect whether insulation cooperation is reasonable. Power equipment on-line monitoring technology recently develops so rapidly, and it is a new technology that spans multi-disciplinary and is applied extensively in the power system. However most of oscilloscopes fail to monitor over-voltage waveform for their frequency despondence so that they can not been used to get real condition. So it's necessary to develop highly performing and automation equipment to implement recording completely and exactly real changing process of voltage when defaults happen, at the same time, saving waveforms and several parameters in order to know condition at that time and affection to power system which can afford some accurate datum for scientific research and operation personnel to analyze reasons for fault and to afford reliable proof whether power system is safe.Over-voltage can introduce insulation accidences, and unsuitable insulation cooperation can create dangerousness to equipment lifespan. All kinds of power equipment so different in insulation construction and operation mode that insulation aging characteristic points and their abstraction is variant;Most of insulation aging theories are based on probability statistics in mathematics, and standard by trials,then get a malhematic model from large quantities of datum, which is of sense in projects. Insulation aging theory affords a good theoretical reference proof whether power equipments is safe, and a decisive action to state maintenances.The paper is composed of three parts. First of all, the author formulates all types of over-voltage and their waveform features after normal insulation cooperation, including arguments and time of duration, etc;introduces conventional method of insulation cooperation to afford a theoretical base of following over-voltage analyses.Secondly, at the aspect of developing over-voltage pick device, using some tools like programmable logic technology and CPU) devices and MAX+phisU, the author explores and researches the coral part about general logic design;then the author prefers "TR2000-B Transient Over-voltage Monitoring And Recording System" developed by Sichuan Power Trial Institute, to obtain analyzing datum, and spends quantities of time to compile up-programs for the device. Using VB and LabVDEW to make a interface of device, it's enough to implement all analyses functions. At the over of the part, the author quotes some classical and frequent over-voltage waveforms and analysis them.Finally, the author takes 2 generator stator winding insulation in Nanya River power plant forecasts its safety. On the one hand, the author formulates generator's insulation construction > aging mechanics > trials and insulation crack judging criterion;on the other hand, the author also formulates generator insulation safetyforecasting theory------Maximal Discharge Quantity Lifespan Forecasting Methodand Aging Discharge coefficient lifespan Forecasting Method (D graphic method);Collect trial datum in the power plant to forecast its lifespan and make a decision of replacing insulation finally, and formulate all kinds of efficiency after insulator renovation. At last, put forward to improvable assumption of Maximal Discharge Quantity Lifespan Forecasting Method, in which the author adds parts of over -voltage conditions of generators' operation to approach to the factThere is some sense to relative subjects about monitoring and analyzing over-voltage or equipments forecasting, and some cases of insulation forecasting and many waveforms can been contrast relatively.