Numerical Simulation of Starting Process of Electromagnetic Speed ​​Regulation Pump Unit

The rule of the excitation current control of the electromagnetic speed regulating motor during the start-up process of the pump unit can be obtained, and verified in a computer supervision and control system at the time of the intermission, and the change of the rotation speed is basically in accordance with the setting of the numerical simulation. The law of speed changes. The research method provides a useful reference for the development of control software for other asynchronous motor dragging speed control equipment, and has a definite practical value. 1 Introduction In the pumping station project, it is possible to adjust the speed of the pumping unit to adapt to changes in the operating conditions. The speed control is the energy saving and optimal operation of the pumping station. The effect is limited to the water unit driven by the electromagnetic speed governing motor. Can be composed of analog regulator + supervision of 1 computer as the structure of the 1 command supervision system 53, to achieve real-time unit speed control and optimal operation.

During the start-up process of the pump unit, it is required to smooth and reduce the impact on the water pump; under the premise of satisfying the requirement of the starting torque, the start-up characteristics of the water pump unit driven by the electromagnetic speed-regulating motor should be reduced as much as possible. Since the control law of the excitation current of the motor is determined, it is necessary to investigate the excitation current and provide the basis for the development. Simply follow the on-site commissioning, experience-only drive system equation of motion = from the machine from the machine motor + her loss pump negative 21 friction and 1 machine-like, for the magnetic clutch to the uniform friction torque and loss of force. 1; The load torque converted to the motor driven shaft is the rotational inertia of the motor driven shaft 12; 602. The angular acceleration of the motor driven shaft 1 and Liu respectively is the motor's driven axis. , Can easily cause accidents, and the debugging process takes a long time, this article intends to use numerical simulation to determine the control law of the excitation current in the pump unit starting process, so that not only can greatly reduce the blindness of on-site debugging, to avoid accidents, And can be combined with on-site commissioning in a relatively short period of time, more accurately determine the control parameters in the screwing software 2 numerical simulation of the electromagnetic speed start process 2.1 Moisture balance equation of the pump unit during start-up process 7-foot pump unit transmission system by electromagnetic adjustment The speed motor consists of a squirrel-cage asynchronous motor and an electromagnetic clutch, wherein the electromagnetic clutch is formed by the armature and the magnetic pole. Transmission equipment and water pump 纟 1. Into, such as the Court 1 according to the conservation of water kinetic energy management theory, there is a water pump rotor flywheel inertia 传动 for the transmission equipment, transmission ratio to meet the requirements of the water chestnut unit start, but also can be set with 2 different The law of pump speed change can be determined without 2.2 excitation current control law According to the requirements of the pump unit start process, you can set the start time and duration of the pump stop speed and pump speed in the starting duration of the law, which can be obtained The pump speed and the pump speed change rate at any time during the start-up period are used. The excitation current of the electromagnetic speed-regulating motor at this time can be calculated by Formula 17, and the control law of the excitation current within the starting duration can be obtained.

3 Example 3.1 Basic information of the pumping station Axial flow pumping station is a small pumping station with a single station. The main electromechanical equipment of the pumping station includes a 3225 type semi-regulated vertical axial flow pump, a 诏191 electromagnetic speed regulating motor and an angle belt transmission device. The rated power of the motor is 55kW, and the angle belt drive ratio is 276. The pump station is realized by a computer supervisory system to realize real-time speed regulation and optimization.

3.2 Numerical simulation According to the basic data of pump station of the pump station, the specific formula of the function in the mouth is as follows: The pump unit start process lasts 3, the pump end speed is 350, and the pump speed, the change law with time is linear, 2 2 The pump speed can be obtained at any time within 8 minutes. You and the speed change rate of the water pump can be calculated by Equation 17 and Formula 18 to obtain the excitation current at the corresponding time, so as to obtain the control law of the excitation current.

This axis is the motor's active shaft speed moxibustion is the coefficient related to the structure type of the electromagnetic clutch, the excitation current 3 her Mozi weight N; i, is the magnetic pole rotor rotation radius m; S is the slip rate; for the water chestnut shaft speed 4 you The kiln is a 7-foot pump unit. The pump speed and the motor follower at the end of the start-up process are considered to have no loss of the electromagnetic clutch torque.

According to the principle of conservation of power, the pump is negative and negative. The pump negative pump shaft power is obtained by equation 912; you are negative for the motor output power; from the pump negative is the load moment of the pump shaft, moment and the friction torque of the water pump. Several chestnuts, chestnuts and oysters are rated shaft power and rated speed of the pump, respectively. , Li, and, respectively, for the water pump bearing friction coefficient, the pump rotor weight and the pump rotor radius of rotation, the definition of the slip rate. 8 From the start of the pump unit, the moment balance equations 1 and 21 sentences, we can see the water pump unit start process The rate of change of the chestnut rotation speed over time is a function of the pump speed and the excitation current of the speed regulation motor. 4 For a pump unit of a certain type, this function is determined, that is, when the time is 53.3. Control software The computer monitoring system of the axial flow pumping station adopts a supervisory computer + calibration regulator structure analog regulator for the solenoid speed control motor wrapper system control the original 4 analog signals supervise the computer output to wring digital children's scriptures, Convert to analog, 315 as the controller's automatic signal. The controllable rectifying circuit in the controller, the pulse phase shifting trigger circuit and the like control the excitation current supplied to the excitation winding of the electromagnetic clutch, thereby driving the pump load operation. The controller adopts a single closed-loop control system. When the speed is negatively feedbacked by a single sensor, the generator captures the supply, and when developing the start-up process control software, how to determine the given rule of the output control digital quantity is a key issue in the premise of the known excitation current control law. Next, according to the definite relationship between the controller's automatic signal and the excitation current, a given law of outputting the analog signal by the computer output and controlling the digital output can be obtained, so that the computer output can control the digital output of a given law. The excitation current control law determined by numerical simulation provides a reliable basis for the given law of the computer output digital station. It is the basis for the development of the software. According to the law of digital supply, the software for starting the process of the pump unit is programmed. Field commissioning and actual operation. The speed change process of the water pump can meet the requirements of the unit start-up requirements in accordance with the speed change rule set by the numerical simulation. The starting process is smooth but it should be pointed out that the first time the unit is started and the unit operation is interrupted for a long time and it needs to be restarted again. These two conditions have slightly different rules for the digital quantity given that the friction torque of the water pump is greatly reduced in the latter case. Therefore, the digital setpoint is smaller than the previous one. The specific value can be determined through the use of a smaller pump friction coefficient. The start-up process control software of the pumping station control system takes these two conditions into account. The results of the operation clearly distinguish between these two conditions is necessary, it can reduce the conclusion of the pump 4 through numerical simulation, determine the electromagnetic motor speed control motor drive 7 undershooting unit in the starting process of the motor speed control law, It is possible to determine the given law of supervising the digital output of the computer and provide a reliable basis for the development of the control software, which has practical significance.

Speed ​​control equipment, such as frequency converter, water conservator, and other accelerating control system, speed control, numerical simulation, more reliable and accurate determination of the important control parameters in the software. Pump station energy-saving technology. Beijing Water Power Press, 1985 2 edited by China Electrotechnical Society. Fan, water pump, AC speed, energy-saving technology. Beijing Mechanical Industry Press, 1990135 3 Pan Xinmin. Microcomputer control technology. Beijing People's Posts and Telecommunications Press, Exciting current tachometer generator transmission electromagnetic clutch controller

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