Load Analysis Of Walking Beam Pump And PMSM Motoring/Generating Dual-mode Driven Technique

Nowadays, the walking beam pump system has been the main equipment onthe oil field for both domestic and overseas. Comparing with other kinds of oillifting equipment, it has its own advantages and disadvantages both. Throughdoing research on the load characteristics, here Permanent Magnetic SynchronousMotor (PMSM) and its four-quadrant driven strategy was adopted, fulfilled thetask of making the walking beam pump operate smoothly and efficiently.Firstly, research on the changing rule of both static and dynamic load ofwalking beam pump was carried out, got the fundamental data for decisionmaking of the driven scheme and control strategy; on the basis of analyzing thepump jack and the polish rod load theoretically, a mathematical model was setupand simulations under different situations were done; an optimum algorithm wasadopted to decrease the maximum calculation orders and improve the efficiencyand accuracy.Research was carried out on the analysis of PMSM four-quadrant driventheory and system design, for not the same as the normal PMSM driven system,PMSM system that can perform a four-quadrant operation is more complex forboth the circuit topology and the control strategy. And then analyzed the PMSMand its control system frequency domain model under Space Vector Pulse WidthModulation (SVPWM or Space Vector PWM) driving; set up the resolver andRDC based circuit for rotor position detection.Considering the periodically load changing and alternating status betweenmotoring and generating, the high Total Harmonics Distortion(THD) along withgrid-side uncontrolled rectifying also the high energy wasting during dynamicbraking, a combined architecture of grid-side Converter and motor-side Converteris proposed, parameters are determined by analyzing its frequency domain model;achieved the phase angle detecting of grid-side voltage vector on the basis ofnovel software PLL; for further suppression of grid-side harmonics, a substitutionscheme of L filter with LCL structure with no changing of other parameters andlow cost is adopted in this article.Finally, joint simulation of the walking beam pump jack torque model, themotor-side and grid-side Converter were accomplished, simulation result and alsothe analysis were given; both hardware and software of the experimental platform are implemented using DSP&MCU TMS320F2812from TI as the core; did theexperimental verification in the laboratory environment.