High-Power Induction Motors Supplied with Voltage Containing Subharmonics

Abstract

In some power networks, components of frequency less than the frequency of the fundamental voltage harmonic called subharmonics or subsynchronous interharmonics occur. In this paper, the effect of voltage subharmonics on currents, power losses, speed fluctuations and electromagnetic torque is examined. The results of numerical computations using the finite element method for an induction cage motor of rated power of 5.6 MW and four motors of rated power of 200 kW with different numbers of poles are presented. An extraordinary harmful effect on high-power induction motors is demonstrated. Among other effects, voltage subharmonics cause significant torque pulsations whose frequencies may correspond to the elastic-mode natural frequency. Possible resonance can result in excessive torsional vibration and the destruction of a power train.

Effects of Voltage Interharmonics on Cage Induction Motors

“…Their basic parameters are listed in Table 1. More details are provided in [34,35]. For the purpose of the paper, analysis with the finite element method (FEM) was employed.…”

“…The 2D numerical computations were carried out using the MAXWELL-ANSYS environment for motor 3-p4 and the ANSYS Electronics Desktop environment (ANSYS Electromagnetics Suite 18.0.0) for the other motors. The applied Tau meshes [34] contained from 4100 to 53,596 elements. The parameters of the models were identified on the basis of constructional and experimental data.…”

“…Thanks to the courtesy of its management he had free access to constructional documentations and the test results of the motors. A detailed description of the used field models is presented in [34,35].…”

“…Undesirable phenomena due to the interharmonics' occurrence have been discussed in numerous works [20][21][22][23][24][26][27][28][29][30][31][32][33][34][35]. In [26][27][28][29][30], induction motors under voltage fluctuations were analysed.…”

“…It should be noted that in [23] the vibration was investigated for the interharmonics of frequencies not exceeding 70 Hz because of the speed limit of the alternator used for the generation of interharmonics. It is also worth mentioning that some of the previous works were mostly focused on the adverse effects of subharmonics [23,32] or were limited solely to them [34,35].…”