Method and device for testing and evaluating tolerance of drive motor system of frequency converter under power supply disturbance

Abstract

The invention discloses a method and a device for testing and evaluating tolerance of a drive motor system of a frequency converter under power supply disturbance. The method comprises steps as follows: 1, an instantaneous voltage disturbance resisting test; 2, a long-time voltage fluctuation test; 3, a harmonic disturbance test. The device comprises a power supply grid, a switch Q1, a switch Q2,a switch Q3, a power supply disturbance generator, a tested frequency converter, a tested electric motor, a pulled power generator, a filter device, a voltage compensator, a storage battery, a measurement control unit, a base, a rotating shaft, a UPS (uninterrupted power supply) and a grid-connected frequency converter. The device has the advantages that the device has accurate voltage regulationand frequency modulation and high fault simulation capability and can realize the functions of energy feedback, coordination control of rotating speeds and torque, high-speed and high-accuracy acquisition of the electric quantity and the mechanical quantity, measurement of temperature rising of a motor winding, control of software and machine starting and stopping, torque control, real-time display, wave recording, switch control as well as data analysis and computation.

Description

technical field [0001] The invention relates to a method and device for testing and evaluating the tolerance to power supply disturbance of a frequency converter-driven motor system, and belongs to the technical fields of power electronics and motor drive. Background technique [0002] At present, frequency converters are widely used in the field of motor drive and control, and play a vital role in saving electric energy, automatic control and improving equipment efficiency. For example, frequency conversion and speed regulation hoists used in the coal industry, high-power rolling mills used in the metallurgical industry, various motors used in the petrochemical industry, and various auxiliary machines used in thermal power plants such as fans, water pumps, and coal feeders. These devices are often in low-load and variable-load operation states, and the purpose of energy saving and efficiency enhancement can be achieved by adding frequency converters. The existing technolog...

AI Technical Summary

Problems solved by technology

[0006] 1. Voltage fluctuations: For example, due to the frequent start-up of large-capacity hoists in the coal industry, the grid voltage fluctuates frequently, which obviously deviates from the rated value

[0007] 2. Unbalanced three-phase voltage: For example, the load asymmetry of the three-phase electric arc furnace in the metallurgical industry causes a high degree of unbalanced three-phase voltage

[0010] 5. Frequency offset: The petrochemical industry usually has a self-provided power plant for combined heat and power generation. For some reason, it is separated from the system to cause isolated grid operation. At this time, when the output of the generator is insufficient to meet the load demand, the frequency of the isolated grid will drop. Even power failure

[0011] On the one hand, the above problems have caused harmonic pollution and power factor reduction to the power grid. On the other hand, they have caused harm to other equipment within the power supply range, resulting in the shutdown of inverter-driven motor equipment, increased loss, noise and vibration, and even damage to original components.

Voltage sags often cause the frequency converter to latch output

Most low-voltage inverters will block the output of power electronic components due to undervoltage protection when the voltage drops to 85% to 90% of the rated voltage for a short time, resulting in shutdown

[0013] 2. The power supply waveform is distorted and the harmonic content is large

Severe distortion of the power supply waveform, such as an instantaneous gap on the voltage sinusoidal curve, will affect the triggering of the controllable components of the inverter rectifier and inverter, and the triggering angle cannot be detected normally, resulting in a protective shutdown

[0014] 3. Unbalanced three-phase voltage

The unbalanced three-phase input voltage will cause the DC bus voltage of the inverter to fluctuate significantly, which will cause an imbalance in the power supply voltage of the motor and cause abnormal heating of the motor

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