SU1342460A2 - Water supply system for irrigation - Google Patents

Abstract

The invention relates to the field of agricultural land reclamation. The purpose of the invention is to increase the reliability of the pumping station by stabilizing the operation of the pump and reducing power consumption by limiting the current of the stator and its electric motor. The system includes a regulating device 1, an alternating current source 2 of adjustable frequency, an electric pump 3, an irrigation network 4, a pressure sensor 5, a pressure setting device 7. The control device 1 is controlled via an adder 6, resistors 11 and 12. and a switch 8 using an inverter 9, two rectifying devices 10 and 13, and a comparison device 14. The feedback target includes a current sensor 15, a reference voltage source 18, an additional comparison device 17 and a second switch 16. The system implements an automated filling mode of the hydraulic network at lower frequencies of pump rotation with increasing frequency as the pipeline is filled, which results in adaptation of the stabilization system and pressure (including with improved dynamic properties) to variations in the load characteristics of the pipeline. The transition to the necessary adjustment characteristic with a weak pressure feedback signal is accomplished by closing negative current feedback i (L N

Description

the stator of the drive motor when the current exceeds the nominal value. This allows you to retain all the advantages of the pressure control system with improved speed, the stability of the electric pump

The invention relates to agriculture, namely to stationary irrigation systems and is an improvement of the device according to the author. St. No. 1243653.

The purpose of the invention is to increase the reliability of the pumping station by stabilizing the operation of the pump and reducing power consumption by limiting the stator current of its electric motor.

Figure 1 presents the block diagram of the system; Fig. 2 shows dependency graphs (H) (characteristics of the hydraulic network and pump of the water supply system).

The water supply system comprises a series-connected regulating device 1, an alternating current source 2 of adjustable frequency, an electric pump 3, a hydraulic irrigation network 4, and a pressure sensor 5, the output of which is connected to the first input of the adder 6, to the second input of which the pressure setpoint 7 is connected. The control device is connected to the key 8. The output of the adder 6 is connected to the inputs of the inverter 9, the first rectifying device 10 and to a common point of resistors 11 and 12.

The output of the inverter 9 is connected to the input of the second rectifying device 13, the output of which is connected to the output of the first rectifying device 10 and to the first input of the comparing device 14. The output of the setting device 7 is connected to the second input of the latter and the control key of the code 8 to the output. Resistors 12 and 13 are connected to the first and second inputs of the key 8, and the input of the regulating device 1 is connected to the output.

unit and limiting, the motor stator current in case of an arbitrary change in the load characteristic of the hydraulic network, avoiding the complexity of the pump station control algorithm, 2 Il.

The system also contains a current sensor 15, the input of which is connected to the output of the alternating current source 2 at a controlled frequency, and the output to the input of the second key 16. The control

the input of the second key 16 is connected to the output of the additional comparing device 17, and the output is connected to the third, the input of the adder 6, and the water supply system for irrigation works as follows.

Reliability and cost-effectiveness of the operation of the pressure irrigation system depend on the correct matching of the Q-H characteristics of the pump to the HQ -H characteristics of the hydraulic network (FIG. 2), i.e. from the correct choice of the operating point of the pump at the intersection of its characteristics (natural or adjusting) with Q - H-characteristic of the hydraulic network (figure 2). In this case, the characteristic of the empty pipeline (curve 2) differs significantly from the characteristic of the full (curve 1), as a result of which point B is located outside the working zone of the pump.

 The operation on the natural characteristic is due to the large mismatch at the output of the adder 6 due to the small signal of the pressure sensor 5. The operation of an electric pump with a nominal frequency at flow rates substantially exceeding the nominal value leads to an increase in the stator current of the drive motor. When the stator current exceeds the nominal value corresponding to the output of the source 18 of the reference voltage, an additional comparison device 17 operates, relocating the key to position 1 corresponding to the connection of the output of the current sensor 15 to the third input of the adder 6, i.e. negative current feedback.

The signal of this feedback reduces the magnitude of the error voltage at the output of the adder 6, translating into an adjustment characteristic with a reduced rotation frequency. This occurs until the pump switches to the characteristic, the point (c) of intersection of which with the characteristic of the empty pipeline (2) will be within the working zone of the pump. The magnitude of the stator current will decrease to the nominal value. In this case, a hopping will occur (with some delay) by the amount of hysteresis of the additional comparing device 17, as a result of which the key 16 will be transferred to the O position and the current feedback circuit will be broken.

Thus, the current during the entire period of filling the pipeline (pump operation mode) will be kept close to the nominal, which ensures the shortest possible filling time. As the pipeline is filled (curves 4,3,2,5,1), the pump moves to the operating point corresponding to the H reference for pressure. The system begins to operate in a pressure stabilization mode with accelerated testing of large mismatches by changing the gain of the regulating device.

In the process of filling the pipeline, the contradiction between increasing the gain of the regulating device and the need to reduce the signal at its output is eliminated by providing a feedback signal on the current to the input of the adder. With the appropriate setting of the current sensor

0 5 0

5 0 5

0

the magnitude of the mismatch will decrease under the action of negative current feedback so much that switching of the comparison device 14 will not occur.

The device is implemented on the elements UBSR-AI. No increase in the number of cells is required.

The use of the invention makes it possible to automate the filling of the pipeline, to increase reliability due to the elimination of situations leading to the triggering of the protection (maximum or thermal) of a serial source of alternating current of adjustable frequency.

Compared with the main unit, the degree of automation and reliability are increased, the efficiency of the installation is stabilized and thus the electrical demand of the system is reduced.

Claims (1)

Invention Formula The irrigation water supply system according to the author, No. 1243653, differs in that, in order to increase the reliability of the pump station operation by stabilizing the pump operation and reducing the electric power consumption by limiting the stator current and its electric motor, the system is equipped with an additional a device, a voltage source connected to the first input of the additional comparison device, a second switch connected between the output of the last and the third input of the adder, and a current sensor connected to the output ohm AC variable frequency and additional inputs connected to the comparator and a second key, Editor P.Geershi Compiled by G.Paraev Tehred M. Didyk. Proofreader S. Shekmar Order 4537/2 Circulation 627 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 FIG. 2