1 speed control system features: speed control device used in the pump station cascade speed control system, 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 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 parameters 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 rectifier bridge and inverter bridge, ABB uses a controllable rectifier bridge, through the rectifier bridge and inverter bridge SCR timing control, to ensure that the inverter bridge will not be short-circuit 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: CASCADE, BYPASS, SCRO. 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.  2 speed energy-saving effect: pump station officially put into operation so far, during the working methods have undergone great changes, pumping unit design lift is 37m, just started running in 1994, speed control unit is debugging, mainly running speed 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, since the speed regulating unit and the constant speed unit work at the same time, we do not distinguish between single unit water supply unit consumption, but only classify the speed regulating unit and the fixed speed unit. 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. Data processing is as follows:   energy saving rate = (89.02-52.82) /89.02×100%=40.67%   on Table 2, the data processing is as follows:   1 # and 2 # unit weighted average unit consumption of 93.91 ( kW · h / 103m3). The weighted average unit consumption of units # 5 and # 6 is 117.58 kW · h / 103m3. The energy saving rate is (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.  3 system maintenance experience and problems: pump station during construction, suffered a 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 to manage this system, we must first have a strong technical maintenance team. In September 1995, 2 # units failed, 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: 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. The crosstalk system has a relatively low power factor of 0.65 based on our original records. 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. Thyristor components will be heated at work, so that the temperature inside the device is very 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 make the system run normally, in addition to cultivating an excellent team technically, we must also have a set of effective methods in management and intensify the management. (1) To establish a file for each device, and use computer management, the device parameters of various regular input, 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) Regularly clean the carbon brush, vacuum cleaner to absorb toner, check the carbon brush wear and pressure are balanced, measuring the 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 clogging may cause SCR components poor heat, 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.