Beam swing angle precision measurement system for pumping unit variable frequency control under complex conditions

RONG Jian-gang， LI Xiao-ying， SHEN Qiang， ZHAO Yan-ming， YUAN Guang-min
（Key Laboratory of Micro/Nano Systems for Aerospace， Nothwestern Polytechnical University, Xi'an 710072，China）

Abstract： Aiming at beam-pumping unit variable frequency drive in oil well，a high-precision and real-time beam swing angle measurement system for variable frequency control was designed，which provides high precision swing angle for the motor speed value curve optimization in order to improve the efficiency and stability. Under complex conditions，moving-average filtering for anti-pulse interference and sectional compensation technique were employed to achieve higher measurement accuracy. The swing angle measuring system online calibration method was proposed to eliminate installation errors effectively. Finally，static and dynamic tests of the beam swing angle system were done. The results indicate that system measurement precision of the swing angle can reach ±0.15° in the range of -50°~+50°，zero bias is ±0.05° with rigorous anti-vibration ability. This measurement system meets variable frequency driver requirements of oilfield under severe conditions.
Key words： oil well； beam-pumping unit； variable frequency control； swing angle measurement； moving-average filtering； zero bias； sectional compensation technique