Introduction：
The pumping unit is the main equipment in the current oil production, the number of which is more than 100,000. The total installed capacity of the electric motor is 35 million KW, and the annual power consumption is more than 10 billion kWh. The electricity consumption of the pumping unit accounts for about 40% of the total electricity consumption of the oil field, and the operation efficiency is very low, the average operation efficiency is only 25%, the power factor is low, and the electric energy waste is large. Therefore, the energy-saving potential of pumping units is huge, and the petroleum industry is also a key industry for promoting "energy-saving of motor systems". By using the D71 frequency converter, the motion law of the pumping unit can be adapted to the changing working conditions of the oil well, so as to improve the system efficiency and achieve the purpose of energy saving and production increase.
Features：
D71 is a wall-mounted inverter, the power range is 0.75KW-500KW, the voltage level of the incoming line voltage is 380V-480V, and the control method is vector control without speed sensor.
D71 has a wealth of control devices, including 8 digital inputs (LI1-LI8), 2 analog inputs (AI), 2 relay outputs (TA), 2 analog outputs (AO), 5V auxiliary power supply for analog power supply Fixed input, 24V auxiliary power supply is used for digital input, all LI/TA, AI/AO can be freely programmed to define functions. MODBUS interface is standard configuration of D71, no option is required. The D71 can be connected to higher-level automation systems via MODBUS.
Advantage：
Good low-frequency torque performance (1.5 times the torque output when open-loop 0.5Hz), low-frequency large torque;
15kW and above are equipped with standard DC reactors, which perform well in harmonic control and stability, helping customers save hardware costs;
It has the advantage of fast torque response, and when the load fluctuates, the current fluctuation is small;
It has good overload capacity and environmental adaptability, and has high operational reliability;
Excellent current limiting characteristics, strong overload capacity, can effectively reduce frequency conversion overload, overcurrent protection, and maximize production continuity;
It has strong environmental adaptability, and the completely independent air duct design can greatly improve the resistance to harsh environments such as oil pollution, dust and damp heat.
System Introduction：
In this system, a D71 110KW inverter drives the 75KW motor of the pumping unit kowtow, and connects the touch screen, PLC and inverter to the system through RS-485 serial communication. The inverter realizes energy consumption braking through braking unit and braking resistor.
Technical Parameter：
| Inverter technical parameters | Device configuration | |
 Model: D71-X | Output current: 215A | One D71 inverter |
| Input voltage: 3-phase, 380-480V | Frequency range: 0-400Hz | 75KW kowtow motor |
| Input frequency: 50/60Hz ±5% | Overload capacity: 150%, 60 seconds | Brake unit |
| Output power: 110KW | Ambient temperature: -10-40°C | Braking resistor |
| Output voltage: 0-480V (the maximum value is determined by the input voltage) | Protection level: IP20 | touch screen |
| PLC | ||
On Site Usage：
According to the on-site space situation, a D71 series inverter is installed in the control cabinet, and the inverter installation and on-site motor are as shown in the figure
Running Result：
The oilfield pumping unit kowtow machine control system using D71 inverter has been put into operation for more than three years, and has achieved good economic and social benefits:
The control device operates reliably, has good environmental adaptability, can resist harsh environments such as oil pollution, dust and damp heat, and has a low failure rate;
The extraction speed can be adjusted dynamically, saving energy and increasing crude oil production at the same time;
Excellent current limiting characteristics, strong overload capacity, can effectively reduce frequency conversion overload, overcurrent protection, and maximize production continuity.
Customer Benefits：
The impact of mechanical parts is small, the amount of equipment maintenance is reduced, and the maintenance cost is greatly saved;
The comprehensive protection function of the inverter ensures maximum production continuity;
The energy saving effect is remarkable, and the crude oil production is greatly increased;
The operation of the system is safe and reliable, and the economic benefits are remarkable.