Method of Efficient Control of the Sucker-Rod Pump Electric Drive

Results of designing of a control mode by the frequency-regulated electric drive of the sucker-rod pump with the induction motor are presented. The designing purpose is increasing energy efficiency of pump electric drive at the expense of electrical energy consumption decrease in a working cycle. Reducing energy consumption is achieved by using the kinetic energy of the unbalanced mechanical parts of the pump, which perform a reciprocating movement in a vertical plane. To implement this principle in a pump electric drive with frequency control asynchronous motor, it is proposed to use not a constant reference signal for the rotation speed of the motor shaft, but a periodically changing signal. In article is given the analytical substantiation of such solution. Mathematical expressions on which basis the speed reference signal should be formed, providing decrease in electrical energy consumption by the pump electric drive, are resulted. By means electrical engineering the expected effect can be provided by application of the special PLC, connected to the reference input of the frequency converter of the pump electric drive. Such PLC will perform the function of a specialized adjuster for the moving speed of the rod of the pump. The electric drive should be added by the position sensor established on a crankshaft of the pump unit and passing a signal about pump bar movement direction to the PLC of speed adjuster. At lowering of a pump rod the speed reference must be smoothly increase, providing growth of kinetic energy stock, and at lifting rod the speed reference must be smoothly decrease, providing the useful expense of kinetic energy stock. Thus, at use of an offered control mode the stream of energy, which is passing through the motor and the frequency converter at invariable volume of pump mechanical work, are decreases. So it defines increase of pump unit energy efficiency.