Application of AD series frequency converter in oilfield pumping unit

 

At present, the total number of pumping units in various oil fields in my country has exceeded 100,000, and they are the main energy-consuming equipment in each oil field. According to the capacity of each motor 30KW (actually more than that, 37KW and 45KW motors are used most in oil fields, and some 55KW and 75KW motors are used), the total installed capacity is more than 3 million kilowatts. As the most energy-consuming equipment used in oil field production, the load rate of the pumping unit drag motor is generally low, resulting in energy waste. In the actual production process, the pumping unit is affected by many objective factors such as the depth of the oil well, oil quality, impurities, sand content, water content and other objective factors. It is necessary to adjust the operation stroke and stroke, and even replace the motor and change the power of the motor; At the same time, due to the different geographic location and latitude of the oil field, and natural factors such as the climate in the area, it will also have an impact on the mining operation, requiring the pumping unit to adjust its speed according to the actual working conditions. In view of the above-mentioned technical requirements of the oil field pumping unit and the social benefits of its use, the basic requirements for the motor control system of the pumping unit are:

☆ A wide range, stable and reliable stepless speed regulation;

☆ It has a significant power saving effect.

1. Energy-saving control cabinet for variable frequency speed regulation

(1) A frequency converter with independent intellectual property rights developed and developed by Audite Electric Co., Ltd. The control object is an ordinary three-phase AC asynchronous motor, and the control accuracy reaches the control level of a synchronous servo motor. Wide speed range, high positioning accuracy, large low-speed torque, and complete software functions. This variable frequency speed regulation and energy-saving control cabinet combines the operating conditions of the pumping unit and the actual conditions of the oil well to timely and automatically adjust the motor's operating speed, acceleration, torque and other parameters, so that the original drive motor can be operated in a highly efficient and energy-saving state. jobs. Through the actual application in the oil field, it is proved that the frequency conversion speed regulation energy-saving control cabinet can carry out speed regulation operation simply and safely, which greatly reduces the work intensity of on-site operators, improves production efficiency, and achieves obvious energy-saving effects.

(2) Features of frequency conversion speed regulation energy-saving control cabinet

The frequency conversion speed regulation energy-saving control cabinet has the following characteristics:

1. AC-DC-AC main circuit

First, the input three-phase 50Hz alternating current is converted into direct current, and then it is inverted into a three-phase alternating current with adjustable frequency and voltage effective value to supply the drag motor.

2. A wide range of speed control

The speed of the motor can be controlled accurately and in a wide range. The speed control range is 0-1500r.p.m, and the speed control accuracy is 0.3r.p.m.

3. Overload capacity of three times rated torque

It has a constant torque output characteristic in the range of zero to rated speed, and has an overload capacity of 3 times the rated torque. Therefore, at a very low speed, the motor can also output rated torque and has a 300% overload capacity.

4. Control characteristics of low speed and large torque

In the process of starting the pumping unit motor, it can drive the motor to output enough torque. Thus, in the process of increasing the speed from 0 to the set value, the current is stabilized and a true "soft start" is realized.

5. Speed ​​control of slow down and fast up

Through the decoupling and independent control of speed and torque, the speed control of the pumping stroke from slow to higher is realized.

6. With internal soft PLC function, it can detect and control the torque.

 
(3) Advantages of frequency conversion speed regulation and energy-saving control cabinet

According to the analysis of the design principles, control characteristics and application examples of the AD series of frequency conversion energy-saving control cabinets, the oilfield pumping unit is equipped with the Deruis series of frequency conversion energy-saving control cabinets, which has the following advantages:

1. Easy to adjust speed

As the AD series AD series frequency conversion speed regulation energy-saving control cabinet has the characteristics of large range and continuous speed regulation, it only needs to adjust a knob to realize continuous and stable speed regulation function to meet the requirements of pumping unit adjustment strokes. For on-site operators, the operation is extremely simple.

2. Reduce work intensity

The use of Aodete AD series frequency conversion energy-saving control cabinet for speed control is easy to operate, and there is no need to change the mechanical structure of the pumping unit and supporting equipment during the operation, which greatly reduces the work intensity of the workers on site.

3. Improve production

 

ADT frequency inverter is applied to diamond wire saw(Diamond beads saw)

i Industry introduction:

Diamond wire saw (machine), also known as diamond beads saw, is the most advanced stone mining equipment, and has been widely used in the stone industry, machinery industry and construction. It is mainly used for the mining and processing of stone, the demolition and repairing of concrete buildings, the processing of brittle and hard materials such as glass.

ii The working principle:

The diamond wire sawing machine consists of main motion system, feed system, diamond beads saw, tensioning device, guiding mechanism, control system, and cooling system etc. The diamond wire sawing is jointly done by a diamond beads rope which directly involved in cutting and a mechanical device that drives the beaded rope movement. Before processing, a piece of beaded ropes are jointed end to end with copper tube casing forming a saw wire loop. During processing, the closed-loop bead rope tensioned on the wire guide set of the wire saw is driven to move at high speed, and the cutting is realized by the grinding motion of the bead. The diamond wire saw is divided into four series according to the cutting object: concrete cutting series, marble cutting series, granite cutting series and heterogeneous cutting series.

III Techniques requirements

The diamond wire sawing machine uses the main motor to drive the sawing rope to run along the track. The sawing rope passes through the drilled hole on the surface to be cut, and the main motor drives the whole sawing machine moving forward along the cutting face with a certain speed through the reducer. The saw rope speed must be adjusted according to the load condition of the main motor and the tension required by the saw rope. If the moving speed is too fast, the load of the main motor increases rapidly, and even overload. And the tension of the saw rope also increases rapidly. The saw wire will be broken if the speed is not adjusted timely. If the moving speed is too slow, the sawing wire tension is drastically reduced, the saw rope will slip on the stone, the cutting efficiency will be reduced, and the slack rope will be twisted to break the saw rope. The key to improve the sawing machine cutting efficiency is to make sure the main motor load balance and sawing wire tension proper.

Due to the irregular shape of the mine or rock, the cross-section is naturally large and small, and the moving speed of the sawing machine must be adjusted in time.

iv the application case

1) electrical configuration:

Main motor: 45KW, 380VAC, 8-poles, rated speed 740 rpm, Current 96A

Feed motor: 1.5KW, 380VAC, 4-poles, variable frequency motor

Main motor frequency inverter: AD300 series, T4, 45KW

Feed motor frequency inverter: AD300 series, T4, 1.5KW

2) Technical plan:

Main motor VFD output the main motor running current from AO1 to the feed motor inverter’s AI2 as the PID feedback value. PID works as auxiliary frequency reference.  External potentiometer is taken as the main frequency reference via AI1. The added value of main frequency and auxiliary frequency is output to the feed motor. The feed motor speed will change according to the PID feedback from the main motor real-time current. This keeps the main motor runs at constant current. The main motor frequency inverter’s frequency reference is set by external potentiometer. The advantage of this solution is that the load control is stable and precise. The feed speed freely adapt to the cross-section load change, system fluctuation is small and cutting efficiency is higher.

iii Inverter wiring diagram:

IV AD300 frequency inverter control features in diamond beads saw

1) the vector control method is adopted to improve the response speed and accuracy of the sawing machine.

2)The low frequency torque is large, and the acceleration and deceleration time is short, which improves the cutting efficiency for customer.

3) The inverter has strong overload capability, which avoids the trip-off in case of high instantaneous transient current when cutting the work piece.

4) The carrier frequency adjustment range is wide, which reduces motor noise and improves the working environment of workers.

5) the circuit board is coated with conformal coating made in Germany, so that the inverter can still run stably under the harsh environment of wet and dusty mine.

V. Conclusion:

The diamond wire sawing machine has been widely used in the stone industry. The diamond wire sawing machine with VFD control is used to extract stone and process various shapes of stone plates (mainly heterogeneous plates), which has the advantages of high production efficiency, good product quality and low cost. It embodies the new development of modern industrial production technology. It is of great significance to obtain high-quality raw materials and various shapes of plates, and also significant to improve he processing quality, production efficiency and economic benefits.