Research And Development Of Variable-frequency Electrical Heating Technique For Pumping Rod

Since the yield of the heavy oil in the world increases gradually, it becomes the main problem in petroleum restricting exploitation of heavy oil, that the heavy oil has high viscosity and bad fluidity. The viscosity of the heavy oil is sensible to the temperature, so heating becomes the main way to extract the heavy oil. At present, many big oil-fields usually adopt electrical heating of heavy oil using hollow pumping rod, which has many good characters, such as heating uniformity, cheaper primary investment, etc. But low heating efficiency, lots of losses , poor power factor and unbalanced three-phase power are the main problems in the single-phase work-frequency power supply, which has been widely used in our country now. To solve the above problems and improve the recovery efficiency of heavy oil and the efficiency of heating, the paper studies and develops a kind of low-media frequency inverter power supply for heating which makes use of the merit of the media-frequency and low-frequency heating fully.Based on analysis, sum-up and comparison of varieties of control ways of variable frequency power-supply for heating, this paper proposes the low-media frequency combination control method, and carries out the designing, simulation, researching, development and realization of hollow pumping rod variable-frequency power supply's main circuit and hardware and software control circuit's by high performance microcontroller 87C196MH as the control core. This system mainly includes the AC-DC-AC frequency conversion main circuit, the examination and protection unit, the microcontroller control unit, the display unit of running status and the driving unit and so on. The output's low and media frequency voltage and frequency of this equipment are independently adjustable, and the user can set 4 parameters according to the different well situation, to achieve the goal of saving energy and enhancing efficiency. In system protection aspect, also with the IGBT drive circuit characteristics, this paper proposes a centralized and decentralized over current protection program, so that the device's reliability is greatly improved. With the long-distance communication function, the user can observe the device's running status and revise the system's parameters through the superior machine and the operation is very safe and convenient. Through digital simulation and test results, the system and control program's correctness and feasibility is proved.