## 5 Conclusions  
The analysis revealed that compensating higher-order harmonics in the traction drive system is more effective in the time domain than in the frequency domain. This study substantiates the choice of a control strategy for the compensator, which is based on damping higher-order harmonics in the phase supply voltage of the asynchronous traction motor. A connection scheme for integrating the compensator into the power circuits of the traction drive is proposed, along with the structural diagram of the compensator control system. An algorithm for synthesizing reference voltage signals is also proposed, based on the use of FOC signals. This approach reduces the implementation time of the control system algorithm and, consequently, improves convergence. As a result, the compensator can be effectively used under both steady-state and non-steady-state operating conditions of the traction drive system. A generalized structure of the transfer functions for filters was developed, enabling dynamic adaptation of the cut-off frequency in response to variations in the supply frequency of the asynchronous motor, without the need to modify the filter structure itself. This is a critical factor for improving the performance of the compensator at supply frequencies different from the nominal value. A simulation model of the traction motor with FOC was developed using MATLAB18b software. A novel method for determining convergence was proposed--defined as the time at which the magnitudes of the spatial vectors of the stator currents in the studied circuit match those in a reference system powered by a sinusoidal voltage source. This approach simplifies the procedure and increases the accuracy of convergence time estimation. Based on the simulation results, the following performance metrics were calculated: torque ripple coefficient, efficiency of the output section of the traction drive, THD, and convergence time. The analysis of the results obtained at the nominal supply frequency of the asynchronous motor, as well as at frequencies below and above nominal, demonstrated that the use of filters with an adaptive cut-off frequency in the compensator control scheme leads to improved efficiency, reduced THD, and lower torque ripple coefficient. The THD value did not exceed 2% in any of the cases, while the torque ripple coefficient remained at 0.3% under steady-state operating conditions. The analysis of the traction drive performance indicators with a reactive power compensator revealed that the most effective solution is the implementation of an elliptic filter in the compensator control scheme. The control scheme incorporating the elliptic filter demonstrated the highest efficiency and superior convergence compared to schemes utilizing other types of filters. A logical continuation of this research involves efforts aimed at improving the energy efficiency of traction drive systems for electric rolling stock equipped with alternative types of traction motors--such as permanent magnet synchronous motors (PMSMs)--and controlled by different strategies, including direct torque control (DTC). Moreover, the findings of this study may be applied to enhance the effectiveness of other reactive power compensation methods, such as the modified d-q method, instantaneous reactive power control in p-q coordinates, and instantaneous reactive power control in extended p-q-r coordinates. Conceptualization, R.M., S.G. and V.L. ; methodology, R.M., S.G. and V.L. ; software, R.M., S.G. and V.L. ; validation, R.M., S.G. and V.L. ; formal analysis, R.M., S.G. and V.L. ; investigation, R.M., S.G. and V.L. ; resources, R.M., S.G. and V.L. ; data curation, R.M., S.G. and V.L. ; writing--original draft preparation, R.M., S.G. and V.L. ; writing--review and editing, R.M., S.G. and V.L. ; visualization, R.M., S.G. and V.L. ; supervision, R.M., S.G. and V.L. ; project administration, R.M., S.G. and V.L. All authors have read and agreed to the published version of the manuscript. This research received no external funding.