High-speed pump speed control applications

Abstract: Shenzhen Donghu Pumping Station adopts 4 speed regulating 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 pump, speed control application

0 profile

?? Shenzhen City Water (Group) Co., Ltd. East Lake pumping station is located in Shenzhen Reservoir Dam 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 pumping station designed by the Beijing Municipal Engineering Design and Research Institute, started in early 1992, the trial run completed by the end of 1993, in May 1994 formally run. The pump room is equipped with 6 horizontal centrifugal pumps, single power of 1 600kW, 4 with 2 spares, of which 4 sets of speed control units selected Sweden 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. ?

1 speed control system features

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 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 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.

?? The system has three operating modes, 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. ?