Improving power and reliability of multilevel frequency converters for drilling rigs

Modern electric drives used in the oil and gas sector are made based on two-level power circuits for voltages up to 1 kV and have a modular cabinet design. The paper presents improvements based on the optimization of the number of modular frequency converters aimed at insuring smooth operation of critical oil and gas applications. Using the method of numerical analysis, the criteria for optimizing the number of phases of the power circuits of the converter in terms of cost, electrical losses and reliability were derived, based on the data on the cost of two-level frequency converters. An economic justification for reducing capital and operating costs when using multilevel frequency converters is given. It is revealed that the proposed optimization methods allow reducing electrical losses due to the reduction of overvoltages on the electromechanical converter, as well those in the DC link. The reliability increase is determined by the operability of the electromechanical converter in the event of a failure of one of its phase winding, taking into account the decrease in the installed power. The results of the introduction of multilevel frequency converters “MOMENTUM” of the MT-1000/MT-2000 series of the Scientific and Technical Center “Privodnaya Tekhnika” LLC are presented.