On-line soft measurement method and device for polished rod load of beam-pumping unit

The invention relates to an on-line soft measurement method and device for a polished rod load of a beam-pumping unit. According to the measurement method, a measurement and control device is adopted to collect input active power of the pumping unit system, a mathematical model among driving motor input electrical parameters, pumping unit four-bar linkage fixed parameters and a pumping unit horse head polished rod load is established, and accordingly soft measurement of the polished rod load of the beam-pumping unit is achieved. The measurement and control device is composed of three working units, namely a beam-pumping unit driving motor electric parameter acquisition unit, a beam-pumping unit driving motor electric parameter processing unit and an output execution unit. The method can accurately monitor the polished rod load of the beam-pumping unit, and effectively overcomes the defects that a conventional measurement method is easily interfered by a working environment, the accuracy of a measurement resul