Self-sensing parallel control of pumps

A hydraulic pumping system for pumping a flow of liquid comprising

• a. a main inlet pipe for supplying a flow of liquid;
• b. a plurality of feeder pipes branching from the main inlet pipe;
• c. a plurality of hydraulic pump assemblies, each of said pump assemblies being in operative fluid flow connection with a branching feeder pipe to control liquid flow through said associated feeder pipe, wherein each of the hydraulic pump assemblies comprises
• d. an electric motor,
• e. a variable frequency drive (VFD) electrically coupled to the motor, and
• f. a centrifugal pump mechanically coupled to the motor;
• g. a main outlet pipe in operative fluid flow connection with the plurality of feeder pipes for outputting the combined flow of liquid;
• and
• h. a controller electronically coupled via a communication channel to the VFD of each of the hydraulic pump assemblies, the controller comprising a programmable device programmed to control the speed of each of the motors via the connected VFD, as follows:
• i. to receive data from each of the VFDs, said data comprising the amount of electrical power consumed by the VFD, the speed of the associated motor, an estimation of liquid flow, and an estimation of head,
• j. to calculate the total aqueous liquid flow through the plurality of pump assemblies,
• k. and to calculate the total system head, and
• l. to vary the speed of each VFD to adjust the total system with respect to the desired system head.