Research On The Energy-Saving Variable Frequency Drive For Beam-Pumping Unit

With the energy shortage and environmental degradation, Energy-saving andenvironmental protection have been paid increasing attention to． On the other side, thebeam-pumping units occupy an important place in the oil production industry． However,the installed motor power is often larger than that required in normal condition to guaranteeadequate overload capacity． In the industrial application, the motor load rate is only about30%．Reason of these, some energy-saving measures should be taken to reduce the powerconsume of the beam-pumping unit．The application of the general variable frequency drive in the oil production industrywas not so good that a dedicated variable frequency drive for beam-pumping units wasdesigned in this thesis, which consisted of DSP system, rectifier/inverter and IGBTdriving-protection circuit．In this thesis, the digital signal processor (DSP) TMS320F28335was used as the coreof the control system, while sinusoidal pulse width modulation (SPWM) and space voltagevector pulse width modulation (SVPWM) technology were made use of in the frequencycontrol system．The AC-DC-AC configuration was adopted as the main circuit of the drivesystem of the dedicated variable frequency drive to achieve energy-saving speed regulationwith high combination of "green environmental protection"． The converter of the grid sideadopted PWM controllable rectifier, which have several advantages such as sine-waveapproximately AC current, controllable power factor, fast dynamic response, bidirectionalpower transmission． What’s more, A double closed-loops PI control system with currentinner-loop and voltage outer-loop was designed． The simulation in MATLAB/Simulinkhad verified that the system design in this thesis was correct and feasible．Based on these study and simulation, a55kW experimental device was designed andthe control program was realized with C language． Some experiments were carried out inoilfield and the performances of the proposed energy-saving equipment had beentested． The results proved the accuracy and effectiveness of the design, as well as obviousenergy-saving effect．...