APPLICATION OF NUMERICAL METHODS TO INVESTIGATE THE INFLUENCE OF LONG-DUARATION VOLTAGE VARIATIONS OF THE DISTRIBUTION GRID ON THE PERFORMANCE CHARACTERISTICS OF LINE-START PERMANENT MAGNET SYNCHRONOUS MOTORS

Abstract

Currently, permanent magnet synchronous motors with on-line starting are being increasingly researched and applied to partialy replace squirrel cage
asynchronous motors, which are commonly used. The reason is that these motors have many advantages such as high efficiency, and high power factor value,
stable speed, higher power density compared to induction motors, and the ability to self-start. However, like other motors, during operation, these motors are
affected by external factors such as voltage, supply frequency, which impact operational parameters, especially power factor and efficiency. With the power
supply, the voltage from the distribution grid usually fluctuates depending on the time of day, month, season, and is typically maintained within permissible
limits. To assess the impact of long-duaration voltage variations of the distribution grid, the paper applies numerical methods to investigate the characteristics
and parameters of the motor when this phenomenon occurs. Based on the research results, the paper will propose some solutions to prevent negative effects
caused by long-duaration voltage variations to ensure the reliability of motor operation in the system.