High-speed pump speed control application summary

[Abstract]: Donghu Pumping Station in Shenzhen adopts 4 speed control units and 2 constant speed units, and the designed water supply capacity is 1.08 million m3 / d. The speed governing system of this pumping station is briefly introduced, the energy saving effect, existing problems and its maintenance and management methods are introduced. [Key words]: High-power pumps, speed control applications 1 Overview  Shenzhen City Water (Group) Co., Ltd. East Lake Pumping Station is located below the reservoir in Shenzhen, is a former water pumping station. Owing to the serious water shortage in Shenzhen, the tap water source came from neighboring Dongguan via 83km and was upgraded to Shenzhen Reservoir via Level 8 and then to Shenzhen and Hong Kong. The daily water supply in Shenzhen Special Economic Zone is more than 1 million m3, mainly provided by Donghu Pumping Station. Due to the concentration of rainfall in Shenzhen in recent years, resulting in drought and water shortage for most of the time, Donghu Pumping Station not only supplies raw water from various waterworks in the SAR but also supplies water to Baoan District. Before the Dongshen Water Supply Project overhaul, Reservoir water storage for use during maintenance. Therefore, the characteristics of Donghu pumping station are as follows: the water supply volume is large, and the daily water supply volume is more than 1 million m3; the head of water supply varies greatly during the year, the center elevation of the pumping station is 6m, the elevation of the water distribution well is 20-40m, The elevation is 58m, the water level of Shenzhen reservoir water level elevation varies between 16 ~ 27m. Therefore, it is very necessary for the pumping station to adopt a speed governor to adapt to different changes in head and water volume.   East Lake Pump Station by the Beijing Municipal Engineering Design and Research Institute, designed to start in early 1992, the end of 1993 completed trial operation, in May 1994 formally run. The pump room is equipped with 6 horizontal centrifugal pumps, single power is 1 600kW, 4 with 2 spares, of which 4 units selected Swedish ABB products, matching pumps used in Japan KUBOTA products. 2 units as a backup speed fixed unit for the Xiangtan motor and Changsha pump. Pump design water supply capacity of 1.08 million m3 / d, has now basically reached full capacity.  2 speed control system characteristics   East Lake pumping station speed governor used for cascade speed control system is ABB's 90 new products, technically advanced. The main control part of microcomputer control, cascade speed control system function settings, parameter settings, operating data display and so on are all concentrated in an operating screen, with flexible and intuitive features. In the monitoring and protection of the motor, it also uses a microcomputer-based integrated protection device, which replaced a large number of intermediate relays and improve system integration and reliability. When the unit is running, the micro-computer dynamically detects the various parameters of the cross-talk system and can display it in the form of bar graph or numerical value on the display screen. The operator can check the desired parameter at any time by pressing the key. When the equipment breaks down, the system will automatically record the breakdown information, the breakdown content appears on the operation screen in the form of the text, may call at any time, in order to help diagnose the breakdown reason. The control system also integrates a six-channel recorder, can be arbitrarily selected six parameters associated with it, in the form of curves on the LCD screen real-time display of parameter changes. When the equipment fails, the channel recorder can lock the information before and after the failure occurred, and study the reason of the failure by studying the parameter changes.   In the design of the rectifier bridge and inverter bridge, ABB uses a controlled rectifier bridge, through the rectifier bridge and inverter bridge SCR timing control, to ensure that the inverter bridge will not be shorted through the rectifier bridge. Eliminating the possible circulation between the rectifier bridge and the inverter bridge. The DC smoothing reactor commonly used between the two bridges can also be omitted, thus saving costs, reducing installation space and power consumption of the smoothing reactor , Inverter bridge and inverter transformer reduce the loss, the overall efficiency increase, because there is no reactor, the entire cascade speed control system on the power supply fluctuations will not be too sensitive.   This system has three modes of operation, namely CASCADE (string), BYPASS (bypass), SCRO (rotor short circuit). Three kinds of working modes not only relate to each other, but also different, the three can be smoothly switched. When the serial speed is running, when the speed reaches the lowest serial speed, the serial input is put into the system. The motor speed can be adjusted between the highest speed and the lowest speed. In bypass operation, the motor starts with a starting resistance, then the starting resistance is shorted, Full speed operation; rotor short-circuit operation, between series and bypass between the way, within the speed range, and the same series control mode, when the given value is greater than the maximum speed range, automatically into the bypass operation, When the given value is within the speed regulation range, the series control system is automatically put into operation again, and the unit operates in the series modulation mode.   $$ Div $$ 3 speed energy saving effect   East Lake Pump Station from May 1994 formally put into operation for more than 5 years, during which the way has undergone great changes, pumping unit design lift 37m, 1994 Just started running, speed control unit is debugging, mainly running speed fixed unit. After commissioning of speed regulating unit, the main running speed governor unit. Initially, due to the small amount of water supply, elevation of the water point low, so the crew work in the low head, high flow conditions, this time low efficiency unit, away from the high-efficiency area. With the gradual increase of water supply, the pressure of water supply gradually increased, and the working lift of the unit increased from less than 20m to 33m, and the unit efficiency was greatly increased. Before December 1995, the working pressure of generating units was basically the same. From the original statements, we sorted out the power consumption per thousand cubic meters of water at speed regulation and constant speed work, which are listed in Table 1. From January 1996 to September 1998 Between, the work style changes a lot. Since October 1998, the working condition has been relatively stable. We select the data from November 1998 to June 1999 as Table 2.  In Table 1, the governor unit and the constant speed unit at the same time work, we do not distinguish between single unit of water supply unit consumption, but only the governor unit and the fixed speed unit classification statistics. In Table 2, 1 # ~ 4 # units are speed control units and 5 # and 6 # units are speed units. Among them, 1 # and 2 # work in the speed control mode; 3 # and 4 # work in speed control mode at some time, and work in constant speed mode at some time. Therefore, in dealing with Table 2, we mainly contrast the relationship between speed and speed. For Table 1, the data are processed as follows:  energy saving rate = (89.02-52.82) /89.02×100%=40.67%  For Table 2, the data processing is as follows:  1 # and 2 # unit weighted average single The unit consumption of 5 # and 6 # units is 117.58 (kW · h / 103m3);  energy-saving rate = (117.58-93.91) /117.58×100%= 25.21%.  Through the above data analysis shows that when the water supply lift is low, the unit is not working in the high-efficiency zone, by adjusting the motor speed, you can change the operating point, so that unit efficiency, and thus energy-saving effect is very significant, saving up to 40% ; When the lift is raised, the unit efficiency is obviously improved, and the basic work of the unit is in the high-efficiency area, and the energy-saving rate still reaches 25%. Visible, energy-saving effect of speed control unit is very good.  4 system maintenance experience and problems   East Lake pumping station during construction, suffered a major flood in a hundred years, some of the equipment has been flooded before. After the system was put into operation, many problems occurred, some were technical problems, some were equipment problems, and some were left over from incomplete flooding treatment. In the past five years, the equipment has basically operated normally and the problems that have occurred have been solved one by one.   Through five years of operation and maintenance, we feel that we must manage this system, we must first have a strong technical maintenance team. September 1995, 2 # unit failure, equipment operation sometimes normal, sometimes tripping, and burning control insurance. A single test each component, are normal; cast DC, found + 5V power is not normal. After analysis of the drawings, paragraph by paragraph test, and finally found a more hidden place, a piece of metal debris ride in the power board between the two feet, when off, clear the metal debris after the device is operating normally.  In the equipment operation, we found that the system still has some problems:   (1) the system is more sensitive to lightning, especially some electronic components. Shenzhen is located in Dorei area, where the pump station is exactly the lightning strike area in Shenzhen. August 1995, there was a lightning strike, Unit 3 trip, fuzzy control speed control screen, restore the DC and reset after normal.   (2) series transfer system power factor is relatively low, according to our original record, the lowest only 0.65. Therefore, it is necessary to install local compensation devices and harmonic absorption devices, but the harmonic absorption devices are prone to failure. Under the action of harmonics, the low-voltage transformers often burn-in phenomenon.   (3) SCR components in the work will be fever, so that the temperature inside the device is high. In summer, the continuous high temperature in Shenzhen caused the temperature in the control cabinet to reach as high as 41 ° C, which is unfavorable for the work of the equipment. Therefore, the ventilation problem of the equipment is very important. Now, we will be part of the surrounding glass removed, the basic guarantee of work, but in the temperature is too high, have to be resolved through other means.   In order to ensure the normal operation of the system, in addition to technically to train a strong team in management also have an effective method to increase management efforts.   (1) to establish a file for each device, and use computer management, the equipment of various parameters regularly entered as historical data for analysis and comparison purposes. Every time the equipment for maintenance, maintenance, replacement of components, timely reflection in the file, be prepared.   (2) Regular cleaning carbon brush, vacuum cleaner suction toner, check the carbon brush wear and pressure are balanced, measuring carbon brush length, when the length is less than the specified value, to be replaced in time.   (3) regular cleaning of the SCR cabinet filter, filter plugging may cause poor heat SCR components, resulting in SCR burned.  ABB string transfer system in my station more than five years of operation, basically normal. System has a certain advanced technology, operation and management more convenient, and its energy-saving effect is more obvious, to achieve the desired goal.