I. High output value and high energy consumption; oil pumping units have great potential for energy saving.
China is one of the countries with the highest energy consumption per unit of output in the world. Among the many technological improvements, the improvement of variable frequency speed control technology can also contribute to energy saving, consumption reduction and quality improvement of products.
Oil fields, as a special industry, have their own unique background. Taking pumping units as an example, they are currently one of the most widely used oil extraction machines and also a major consumer of electricity in oil fields, accounting for about 40% of the total electricity consumption of oil fields.
Oilfield pumping unit loads are uniquely time-varying loads, exhibiting both dynamic and static characteristics. Initially, the starting torque of the drive motor must be 3-4 times, or even greater, than the actual load of the pumping unit. Starting torque is the primary factor in selecting a motor for the pumping unit. If the starting torque is insufficient, the load power will inevitably be mismatched, with the operating load power far below the motor's rated power—a phenomenon known as "overpowered operation." Excessive pumping capacity increases the time the pumping unit is idle, resulting in high electricity costs for oil well extraction and significant energy waste.
This demonstrates the significant energy-saving potential of oil pumping units, and frequency conversion retrofitting of these units can substantially reduce the total electricity consumption of oilfields. Frequency conversion energy-saving retrofitting of oil pumping units has also become one of the main measures for optimizing and upgrading oilfield equipment and facilities and for energy-saving retrofitting under the current "carbon neutrality" context.
II. INVT GD300-29 Energy Feedback Inverter Solution
Currently, most commonly used beam pumping units employ a counterweight-based operating method, and their overall structure resembles a balance scale: one end is the pumping load, and the other end is the counterweight load.
For the pumping unit, if the torque generated by the pumping load and the balancing load is equal or changes in the same direction, then a very small amount of power is needed to make the pumping unit work continuously without interruption. In one working cycle of the pumping unit, there are two electric operation states and two generator operation states.
1. System block diagram of the variable frequency control cabinet for the oil pumping unit
2. Wiring diagram of GD300-29 frequency converter
When the pumping unit is in generator operation, in traditional methods, regenerative energy is consumed as heat through a braking resistor. INVT has introduced the GD300-29 energy feedback solution, which uses PWM control for the rectifier and features four-quadrant operation.
The solution not only meets the speed regulation requirements of potential loads but also converts the regenerative energy of the motor into electrical energy to be fed back into the power grid, achieving maximum energy saving. Simultaneously, current harmonics are controlled within 5%, reducing harmonic pollution to the power grid.
III. Advantages of INVT's Solution
In addition to the traditional advantages of frequency conversion retrofitting of oil pumping units, the GD300-29 energy feedback frequency converter solution, as an upgraded version of the frequency converter + energy feedback unit solution, also has unique advantages.
"Combining multiple advantages to maximize energy savings"
① It greatly improves the power factor (from the original 0.25-0.5 to over 0.9), significantly reduces the supply current, thereby reducing the burden on the power grid and transformers and lowering line losses.
② The extraction speed can be dynamically adjusted according to the actual fluid supply capacity of the oil well, which can achieve energy saving and increase crude oil production at the same time.
③ It achieves "soft start", avoiding excessive mechanical impact on the motor, gearbox and oil pump, extending the service life of the equipment and improving production efficiency.
④ The rectifier section of the GD300-29 inverter adopts IGBT and PWM rectification mode, making it a true four-quadrant inverter. Regenerative energy is converted into electrical energy and sent back to the grid, resulting in high feedback efficiency and an average power saving rate of over 30%.
⑤ The integrated design of rectifier and inverter has a higher degree of integration and greatly saves cabinet space.
⑥ Current harmonics are controlled within 5%, reducing harmonic pollution to the power grid. Optional filter capacitors are also available, making it even more suitable for weak power grid environments.
IV. Development Vision
In recent years, oilfields including Daqing Oilfield, North China Oilfield, Changqing Oilfield, Yumen Oilfield, and Yanchang Oilfield have all chosen INVT GD300-29 energy feedback frequency converters.
Currently, over 1,000 GD300-29 pumping units have been used in oilfield pumping unit retrofit projects, covering power ranges from 7.5kW to 75kW, with an average energy saving rate of over 30%.
In the petroleum industry, INVT not only continues to focus on traditional applications such as pumping units, submersible electric pumps, water injection pumps, and oil transfer pumps, but also demonstrates strong market performance in high-end applications such as oilfield drilling rigs, including mud pumps, winches, rotary tables, and top drives. INVT's GD800 multi-drive solution and GD3000 medium-voltage three-level solution have proven effective in these applications. Looking ahead, INVT will continue to deepen its presence in the petroleum industry, contributing to the development of China's petroleum sector.
