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НаименованиеMicroprocessor Control for the Long-Stroke Pumping Unit

 

This article describes the structure and components of the microprocessor controller for a long-stroke pumping unit for the extraction of oil, as well as the various modes in which the control unit can operate the pump.

Sucker rod pumps are used at many oil wells, but certain working conditions can make it difficult to use this type of pump, and the way that these pumps operate causes them to frequently be offline. One way to address these problems is to use long-stroke pumping units, which employ a plunger to raise the level of the oil and which last longer and produce oil more efficiently.

Orenburg State University, along with the Russian Technical Physics Research Institute, has developed a long-stroke pumping unit that is comprised of a motor for turning the pump wheel, an electric motor, a gear box, a mobile platform, a control unit and an electric brake. The use of a microprocessor control unit allows for setting the cycle height/depth, the speed of the cycle and the pause at the highest and lowest points of the cycle. The control unit also allows the pump to run manually, automatically or remotely.

The control unit consists of a power supply; a discrete input module for receiving signals from the pump's motor and other sensors; a discrete output module for sending control signals to the pump unit; an analog input unit for receiving signals from the motor; a controller for processing signals from the primary sensors, set times and control signals for the motor; a keypad for setting operational parameters; a display to show the pump's status; ROM to hold the software for running the pump; and RAM to hold temporary data.

Since these pumps are designed for use in the field, all their components must be able to withstand a wide range of temperatures. The components that best meet this requirement are from Octagon Systems, so modules from this firm's MicroPC series were used in designing the control unit.

The control unit includes a 6040 microprocessor control module and two 5624 isolated discrete input/output modules. The 6040 module has an analog input port, a processor, a parallel port, two serial ports, ROM and RAM. The parallel port is used to connect a KP-3 hermetically sealed 16-key keypad, while the COM2 serial port is used to connect to a VF display (the 03612 Century from Industrial Electronic Engineers).

The microprocessor and input/output units are mounted in a four-slot 5204 RM box from Octagon Systems. The keypad, display and external signals are connected using CMA cable, STB terminal boards and an ATB-20 terminal board. The whole box is mounted in a Conceptline enclosure by Schroff/Hoffman.

Software for the pump, written in C, allows for manual, automatic and remote modes of operation. Remote operations employ an offsite computer connected to the control unit through an RS-232 interface. In this case, all the control commands and display output are handled through the offsite computer.


Traditional pumping unit.

View of the long-stroke pumping unit

By Oleg Zhugin, Vladimir Kalintsev, Boris Sirota, Vyacheslav Sorokin

Oleg Zhugin,  Vladimir Kalintsev,  Boris Sirota,  Vyacheslav Sorokin