Current-Limiting Soft Starting Method for a High-Voltage and High-Power Motor

Abstract

Focusing on the starting problems of a high-voltage and high-power motor, such as large starting current, low power factor, waste of resources, and lack of harmonic control, this paper proposes a current-limiting soft starting method for a high-voltage and high-power motor. The method integrates functions like autotransformer voltage reduction–current limiting starting, magnetron voltage regulation–current limiting starting, and reactive power compensation during starting, and then the power filtering subsystem is turned on to filter out harmonics in power system as the starting process terminates. According to the current-limiting starting characteristic curve, the topological structure of the integrated device is established and then the functional logic switching strategy is put forward. Afterwards, the mechanisms of current-limiting starting, reactive compensation and dynamic harmonic filtering are analyzed, and the simulation and experimental evaluation are completed. In particular, the direct starting and the current-limiting are performed by developing a simulation system. In addition, a 10 kV/19,000 kW fan-loaded motor of a steel plant is chosen as the subject to verify the performance of the current-limiting soft starting method. As shown by the experimental results, the motor’s starting current is about 2 times that of its rated current, the power factor is raised to over 0.9 after the reactive power compensation, and the harmonic filter can effectively eliminate current harmonics and reduce the total harmonic distortion (THD) of supply currents.

Theory analyses and applications of magnetic fluids in sealing

“…However, the starting resistance torque varies with the environment and standing time, which may cause the sealed equipment fail, and thus further research on the starting resistance torque is necessary. Large diameter shafts are widely used in various heavy equipment, such as high-power motors [164], shield machines [165], and propeller shafts of ships [166]. Due to the large diameter of the shafts, the radial runout of the shafts also increases, which will cause friction and wear between the shafts and the pole teeth, and even damage the sealing structure.…”

Research on start-up characteristics of electric motor driven reversely by hydraulic pump/motor

“…In the reverse driving process, the electric motor load is 0. Combine equation ( 6) to equation (7):…”

“…Researchers have proposed a variety of solutions for optimizing algorithm strategy. Wang et al 7 proposed a current soft method that combines autotransformer voltage reduction–current limiting starting, magnetron voltage regulation–current limiting starting, and reactive power compensation during starting to solve the problem of large start-up current for high-voltage and high-power motors. The method effectively improves the power factor of the electric motor while also lowering the start-up current.…”

A Proposed ANN-Based Acceleration Control Scheme for Soft Starting Induction Motor

“…A soft starter scheme has several advantages compared with several starting schemes. It has high effectiveness and low cost [5][6][7][8][9]. The soft starter mainly consists of a set of backto-back thyristors connected with stator motor windings.…”