Case Analysis For Failures Of Equipment Protection In Tai’erzhuang Pumping Station Of South-to-North Water Diversion Project

Safe and reliable operation of mechanical and electrical equipment in pumping station is one of key problems for the East Route Project of South-to-North Water Diversion.At present,automatic operation management mode is used in new large-scale pumping stations,but the automation system is still not perfect now.In the actual operation of pumping stations,sometimes there are false alarms of transformers,motors,pumps and water levels and other major equipment,which will result in stopping operating to check and eliminate the false appearance of equipment failure.The normal operation of the pump station is affected seriously.Therefore,based on the experience of dealing with misoperation problems of equipment protection,the cases of equipment protection misoperation for the main equipments in Taierzhuang Pumping Station have been investigated and analyzed.According to the principle of seeking truth from facts,the improvement measures were put forward,and it is good for improving the opertional reliability of pumping station.The main achievements of this paper are as follows:1.After investigating and analyzing the misoperation cases of transformer temperature protection system,the main reasons for misoperation of transformer temperature protection system are found,i.e.equipment installation is not standard,connector of signal output cable of on-site temperature measurement protection instrument occurs,which leads to short circuit between cores and acceptance of wrong signal by protection device,thus misoperation of protection was triggered.Based on the analysis and research,emergency measures for eliminating faults and preventive measures and suggestions for preventing similar malfunctions are put forward.Through the implementation of various measures,the false alarm fault of transformer temperature protection is eliminated and the safe operation rate of the pumping station is effectively raised.2.By analyzing the case of misoperation of motor temperature over-high protection system,the reasons for misoperation of protection are obtained:defective temperature measuring circuit of main motor and logic judgment procedure of protection result in that the temperature measurement and protection system is prone to sudden change of temperature and can not be filtered,thus misoperation of protection is occured.The measures for improving connection mode of temperature measurement cable and optimizing logic judging procedure are put forward.By optimization and improvement,the fluctuation of temperature measurement data is reduced,and the reliability of temperature measurement protection system is improved.3.By analyzing the case of misoperation of protection system for cooling and lubricating water cut-off of water pump,the reasons for misoperation are obtained:the operation mode of pumping station in South-to-North Water Diversionr Project is special,so that the damage rate of thermal current indicator is increased and service life is reduced.At the same time,single-point measurement of measuring signal of current indicator leads to low fault tolerance rate of the system,which results in misoperation of protection.The measures for improving the usage condition of flow signal and optimizing logic judging procedure are put forward,and the reliability and fault-tolerance rate of protection system are improved.4.By analyzing the case of of water level misalarm in outlet pool of pumping station,the main causes of water level misalarm are obtained,i.e.air pipe of water level sensor is blocked and accurate atmospheric pressure can not be obtained through connecting the atmosphere,which results in the final measured water level changing with outside temperature and thus causes water level misalarm in outlet pool.The measures for eliminating and preventing water level protection misalarm are put forward.After eliminating the water level meter failure,water level protection alarm disappears and water level measurement data returns to normal.The typical cases of mis-alarm and mis-action are summarized for the equipment protection in Taierzhuang Pumping Station in recent years.From the aspects of installation mode of sensors,installation mode of signal transmission lines,logic judgment procedure setting of equipment protection and parameter setting of equipment protection,the causes of equipment protection failure are studied,the defects and shortcomings of protection system are found.The rationality of equipment protection design is anaylzed,and the improvement measures and suggestions are put forward.The reliability of equipment protection system in Taierzhuang Pumping Station is enhanced through implementation of improvement measures.Meanwhile,it has important reference value and guiding significance for analysis and judgment of misoperation of equipment protection optimization and improvement of equipment protection system and improvement of reliability in other large pumping stations of South-to-North Water Diversion.