Abstract: Water resources and energy shortage are the important factors restricting the economic development of our country. Water-saving and energy-saving are the basic national policies for the sustainable development of social economy in our country. Key words: Frequency-conversion speed regulation technology Water-saving energy-saving Urban-rural water supply Agricultural irrigation Automatic control device 1 Background and Technical innovation Water resources and energy shortage are the important factors restricting China's economic development, water saving and energy saving is the basic national policy of sustainable development of social economy in the United States from the 1990s, the frequency of water-saving energy-saving technology is applied to translation, shaft rotation Irrigation and pipe irrigation systems, the test of its energy-saving rate of 39% to 56%, water-saving rate of 15% to 30%, not only stabilize the pipe network pressure and improve irrigation quality, but also water and energy saving, easy to automate management , But its price is expensive.At that time, in our country urban and rural water supply and pump pumping system, once the pump started to work, the motor will run at rated speed, and the rated water supply, when the water consumption decreases or in the water trough, the pipe network Pressure is too high, the faucet (or nozzle) and the water pipe is often damaged, so that the water flow out, the power consumed in vain; System through the valve to control the amount of water, to reduce the pressure on the water supply network, which also resulted in the waste of electricity and water resources. "Ninth Five-Year" period, China in the industry will be the exchange of variable frequency speed regulation technology as a new technology promotion project, At that time, the water conservancy sector was not applied in the irrigation area.In order to improve the waste of resources and produce a low-cost, agriculturally-acceptable frequency-conversion water-saving and energy-saving control device, the Northwest Institute of Hydraulic Research under the Ministry of Water Resources undertook the "948" Water saving and energy saving technology ", the key technology of this project is AC variable frequency speed regulation technology.In December 1998, we introduced the German 8210 and 8220 series inverter standard specifications, technical indicators, performance parameters detection methods and some prototypes. Technology can be broadly divided into two kinds of direct - AC frequency and AC - AC frequency, we introduce the direct - AC frequency conversion technology, which is commonly seen in the inverter frequency conversion technology used most of our technology is the introduction of key technologies and Its digestion and absorption, on this basis, the development of peripheral technology, development and production of frequency-energy-saving energy-saving products, and To promote the application of the technology after the introduction of the prototype of our imported performance parameters were fully measured and recorded on the basis of digestion and absorption developed four series of frequency control speed water-saving devices, the frequency of water-saving Energy-saving products in addition to the inverter and PLC, the other has all the domestic.This article describes the CX-B series constant pressure water supply automatic control device and CX-D series of constant pressure water saving irrigation automatic control device. The project's technological innovation Point: (1) The application of AC variable frequency speed regulation technology in urban and rural water supply and agricultural irrigation, water saving and energy saving effect; (2) According to project needs, developed their own water level display controller to improve the degree of automation; (3) Need to develop a multi-stage pressure setting conversion circuit to adapt to a variety of agricultural irrigation methods; (4) the frequency control technology, programmable control technology, water level display control technology, pressure sensing technology were integrated 2 Frequency Control The basic principle of AC induction motor rotor speed n can be expressed as follows f - stator power supply frequency; p - motor pole pairs; s - asynchronous motor slip rate can be seen from equation (1), when the smooth change of the asynchronous motor supply frequency f, you can change the motor rotor speed n .. According to the water pump (2), (3), (4), we can see that the speed control ratio is based on the flow rate control Can greatly reduce the shaft power 3 CX-B series of constant pressure water supply automatic control device 3.1 The basic structure of the entire constant pressure water supply system CX-B series of constant pressure water supply automatic control device and pump motor combination (see Figure 1) The device consists of frequency converter (including PID regulator), programmable time switch, programmable logic controller (PLC), water level display controller, remote pressure gauge, water level sensor and related electrical control components, is a With the frequency control and automatic closed-loop control of mechatronic intelligent devices (see Figure 2), which can simultaneously one or more three-phase 380V, 50Hz pump motor for automatic control. System components Figure 2 frequency conversion constant pressure water supply automatic control device block diagram of the principle of 3.2 Working principle CX-B series inverter constant pressure water supply automatic control device to work in frequency conversion mode, the pump motor starting with a soft start after the operation by the remote pressure gauge The actual pressure of the water supply network is detected. The actual pressure of the network is compared with the set pressure to output the deviation signal. The deviation signal controls the frequency of the power supply output from the inverter and changes the pump speed so that the pressure of the network continuously approaches the set pressure. The closed-loop control system through continuous testing, continuous adjustment of the pipeline pressure to achieve a constant, so that the pump automatically adjust the amount of water supply to achieve the purpose of energy saving. PLC's main control: (1) control of multiple pumps (Including spare pump), it will start the cycle softly, and work in frequency conversion mode periodically; (2) Control the automatic start of spare pump.When the first pump motor runs in frequency conversion mode and reaches the rated power (that is, the inverter output power frequency reaches 50H), while the water supply network pressure does not reach the set pressure, the second pump motor will be from Start, and run in frequency mode, then if the pipe network pressure can not reach the set pressure, the third pump motor will start automatically, the first pump is still running in frequency conversion mode to achieve the purpose of maintaining pipe network constant pressure , The number of pumps put into operation is automatically controlled by the device according to the pipe network pressure.The water level display controller is provided with three water level control limits of upper, middle and lower, when the water level of the water tank is lowered from the upper limit to the middle limit, the controller outputs the makeup water pump to start When the water level reaches the lower limit, the controller outputs the stop signal of the water pump to stop the water intake pump until the water level reaches to the upper limit. When the water level reaches to the upper limit, the controller outputs the stop signal of the water pump to stop the water replenishment. After the limit, the controller will automatically take the water pump to recover the water 3.3 Control Function CX-B series of constant pressure water supply automatic control device has the following control functions: (1) with manual / automatic switching circuit, when switched to automatic position The system can automatically adjust the speed of the variable frequency pump and automatically start and stop the standby pump according to the change of the outlet pressure to keep the outlet pressure constant, Frequency control circuit fails, you can switch to the manual position, the pump runs directly under the power frequency to ensure normal water supply; (2) can be set within 1d 1 ~ 9 water supply period, the water supply time of the day can be a day Different; (3) with PLC control of the pump (including spare pump) full-cycle soft-start, periodically automatically exchanged to the pump life is basically the same; (4) after the underground reservoir water pump automatic shutdown protection, Automatic power-up, fill the water after the pump automatically shut down, the reservoir water level to digital display; (5) fault display and alarm, with phase, short circuit, overheating, overload, overvoltage, undervoltage, leakage, instantaneous power failure Protection and other electrical protection functions 4 CX-D series of constant pressure water saving irrigation automatic control device 4.1 The basic structure The entire constant pressure water supply system by the CX-D series of constant pressure water saving irrigation automatic control device and pump motor combination (see Figure 1). Some water-saving irrigation base design sprinkler irrigation, micro-sprinkler irrigation, drip irrigation and other irrigation methods, different irrigation methods require different working pressures in order to make the same water supply pipe The network can provide different working pressure for different irrigation modes. Multi-stage pressure setting conversion circuit is added to CX-B series inverter constant voltage control device, which can automatically control one or more three-phase water pump motors at the same time See Figure 3