In recent years, with the continuous deepening of building an environment-friendly and resource-saving society, energy conservation has been paid more and more attention by the whole society. Oil production plants regard energy conservation as an important task, especially power conservation, which has become a The top priority of energy saving work.
1. Working characteristics of beam pumping unit
The movement of the beam pumping unit is to lift up and down repeatedly, one time per stroke, and its power comes from two relatively heavy balance weights driven by the electric motor. When descending, the oil production rod is raised to bring oil to the wellhead. Due to the constant speed of the motor, when the slider is lowered, the load is lightened, and the energy generated by the motor dragging cannot be attracted by the load, causing the motor to enter the state of regenerative power generation, and the excess energy is fed back to the grid, causing the voltage of the main circuit bus to rise. It is bound to have an impact on the entire power grid, resulting in a decline in the power supply quality of the power grid, a decrease in power factor, frequent high-voltage shocks will damage the motor, shorten the life of the motor, and increase the amount of maintenance.
On the other hand, in order to overcome the large starting torque of the beam pumping unit, the motor used is far larger than the actual required power. The utilization rate of the motor is generally between 20% and 30% during operation, and the maximum will not exceed 50%. , The motor is often in a light-load state, resulting in a waste of motor resources. And the working condition of the pumping unit changes continuously, which all depends on the state of the ground. If it is always in power frequency operation, it will inevitably cause a waste of electric energy. In order to save energy and improve the working efficiency of the motor, frequency conversion transformation is required.
In order to solve the above problems, the frequency conversion technology can be introduced into the control of the beam pumping unit. According to the motor theory, the speed formula is:
Among them: p is the number of pole pairs of the motor, s is the slip rate, f is the frequency of the power supply, and n is the actual speed of the motor. It can be seen from the formula that the motor speed is approximately proportional to the frequency, and the motor speed can be adjusted smoothly by changing the frequency, so that the pumping speed of the oil lifter can be continuously changed. The working frequency of the motor is determined according to the working current of the motor, so that the stroke of the pumping unit can be adjusted conveniently according to the change of the well condition, so as to achieve the purpose of saving energy and improving the power factor of the power grid. At the same time, the frequency conversion speed controller has a low-speed soft start, and the speed can be adjusted smoothly in a large range. It has complete protection functions for the motor, such as short circuit, overload, overvoltage, undervoltage and stall, etc., which can effectively protect the motor and mechanical equipment, and ensure that the equipment is in good condition. Working under a safe voltage, it has many advantages such as stable and reliable operation, and improved power factor. It is an ideal solution for the transformation of oil production equipment.
2. Advantages of pumping unit driven by frequency converter
(1) The power factor is greatly improved (it can be increased from 0.25 to 0.5 to more than 0.9), and the supply current is greatly reduced, thereby reducing the burden on the power grid and transformer, and reducing line loss. The frequency conversion transformation aimed at improving the quality of the power grid and reducing the impact on the power grid. This is mainly concentrated in the occasions where the power supply enterprises have high requirements on the quality of the power grid. In order to avoid the decline of the quality of the power grid, frequency conversion control needs to be introduced. The main purpose is to reduce the impact of the working process of the pumping unit on the power grid.
(2) According to the actual liquid supply capacity of the oil well, the pumping speed can be dynamically adjusted, on the one hand to achieve the purpose of energy saving, and at the same time to increase the crude oil production.
(3) The “soft start” has been realized, which avoids excessive mechanical impact on the motor, gearbox and pumping unit, prolongs the service life of the equipment and improves the production efficiency.
In recent years, with the continuous deepening of building an environment-friendly and resource-saving society, energy conservation has been paid more and more attention by the whole society. Oil production plants regard energy conservation as an important task, especially power conservation, which has become a The top priority of energy saving work.
1. Working characteristics of beam pumping unit
The movement of the beam pumping unit is to lift up and down repeatedly, one time per stroke, and its power comes from two relatively heavy balance weights driven by the electric motor. When descending, the oil production rod is raised to bring oil to the wellhead. Due to the constant speed of the motor, when the slider is lowered, the load is lightened, and the energy generated by the motor dragging cannot be attracted by the load, causing the motor to enter the state of regenerative power generation, and the excess energy is fed back to the grid, causing the voltage of the main circuit bus to rise. It is bound to have an impact on the entire power grid, resulting in a decline in the power supply quality of the power grid, a decrease in power factor, frequent high-voltage shocks will damage the motor, shorten the life of the motor, and increase the amount of maintenance.
On the other hand, in order to overcome the large starting torque of the beam pumping unit, the motor used is far larger than the actual required power. The utilization rate of the motor is generally between 20% and 30% during operation, and the maximum will not exceed 50%. , The motor is often in a light-load state, resulting in a waste of motor resources. And the working condition of the pumping unit changes continuously, which all depends on the state of the ground. If it is always in power frequency operation, it will inevitably cause a waste of electric energy. In order to save energy and improve the working efficiency of the motor, frequency conversion transformation is required.
In order to solve the above problems, the frequency conversion technology can be introduced into the control of the beam pumping unit. According to the motor theory, the speed formula is:
Among them: p is the number of pole pairs of the motor, s is the slip rate, f is the frequency of the power supply, and n is the actual speed of the motor. It can be seen from the formula that the motor speed is approximately proportional to the frequency, and the motor speed can be adjusted smoothly by changing the frequency, so that the pumping speed of the oil lifter can be continuously changed. The working frequency of the motor is determined according to the working current of the motor, so that the stroke of the pumping unit can be adjusted conveniently according to the change of the well condition, so as to achieve the purpose of saving energy and improving the power factor of the power grid. At the same time, the frequency conversion speed controller has a low-speed soft start, and the speed can be adjusted smoothly in a large range. It has complete protection functions for the motor, such as short circuit, overload, overvoltage, undervoltage and stall, etc., which can effectively protect the motor and mechanical equipment, and ensure that the equipment is in good condition. Working under a safe voltage, it has many advantages such as stable and reliable operation, and improved power factor. It is an ideal solution for the transformation of oil production equipment.
2. Advantages of pumping unit driven by frequency converter
(1) The power factor is greatly improved (it can be increased from 0.25 to 0.5 to more than 0.9), and the supply current is greatly reduced, thereby reducing the burden on the power grid and transformer, and reducing line loss. The frequency conversion transformation aimed at improving the quality of the power grid and reducing the impact on the power grid. This is mainly concentrated in the occasions where the power supply enterprises have high requirements on the quality of the power grid. In order to avoid the decline of the quality of the power grid, frequency conversion control needs to be introduced. The main purpose is to reduce the impact of the working process of the pumping unit on the power grid.
(2) According to the actual liquid supply capacity of the oil well, the pumping speed can be dynamically adjusted, on the one hand to achieve the purpose of energy saving, and at the same time to increase the crude oil production.
(3) The “soft start” has been realized, which avoids excessive mechanical impact on the motor, gearbox and pumping unit, prolongs the service life of the equipment and improves the production efficiency.
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