EQUIVALENT CIRCUITS OF HIGH-VOLTAGE SYNCHRONOUS TURBO-MOTORS FOR CALCULATION OF NONSINUSOIDAL MODES OF POWER SUPPLY SYSTEMS

The article considers the non-sinusoidal modes of power supply systems with powerful high-voltage synchronous turbo-motors. Powerful high-voltage synchronous turbo-motors of industrial enterprises designed to drive pumps, compressors, superchargers and other high-speed machines are generally referred to the first category electrical consumers and, when connected directly to the electrical power network, are considered to be the most sensitive to the non-sinusoidal modes of a power supply system, as in the conditions of the supply voltage quality deterioration the loss of their static and dynamic stability can occur. The authors considered the original equivalent circuit of high-voltage synchronous turbo-motors along the longitudinal and transverse axes within the synchronous steady state condition. On the equivalent circuit a real three-phase stator winding of a motor is represented as the system of two orthogonal rotating loops - longitudinal and transverse, and a solid cylindrical rotor – as an excitation winding circuit, longitudinal and transverse damper circuits. The article gives the equivalent circuit of high-voltage synchronous turbo-motors for higher harmonics along the longitudinal and transverse axes, which additionally includes the increase in active and inductive resistance of stator and rotor at high frequencies, and the slip of n-th harmonic of a rotating magnetic field. The authors obtained the analytical expressions for determination of the parameters of the equivalent circuit of high-voltage synchronous-turbo motors when calculating non-sinusoidal modes of power supply system. The expressions obtained for the average equivalent complex resistance of synchronous turbo-motors for the n-th harmonic allow to determine the higher harmonics currents that occur in the stator windings, and assess their unfavorable effect on the condition of retaining of simultaneous steady-state mode within non-sinusoidal power supply system modes.