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Five big impact on the power system of the harmonic wave in the power grid
Category: Industry News
Date: 2019-01-21
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3 the major effect of the harmonic of motor, the motor is cause additional loss, followed by mechanical vibration, noise and harmonic overvoltage.
Polaris smart grid online news: in recent years, with various types of rectifier and converter equipment, electronic equipment, electric arc furnace, converter, the application of electrical appliances and lighting equipment, make the grid voltage and current distortion, grid generated a lot of high order harmonic of the grid. Harmonic effects: 1, transformer for transformer harmonic current can lead to copper loss and spurious copper loss increases, the harmonic voltage iron loss will increase. Basic wave and pure running, in comparison with sinusoidal current and voltage harmonic of transformer temperature rise of the overall impact is high. It is important to note: the additional loss caused by harmonic with the square of the current and frequency ratio rose, thus resulting in a decline in the fundamental wave load capacity of the transformer. But harmonic can also lead to the transformer noise increases. Dielectric loss tester 2, power cable in the heat generated by the central sine wave current conductor and compared with the same root mean square value of pure sine wave current, non sine wave will have higher heat. The additional temperature rise is known as caused by skin effect and proximity effect, and the two phenomena depends on the frequency and the size and spacing of the conductor. These two effects as increase conductor alternating current resistance, thereby causing I2Rac loss increased. 3 the major effect of the harmonic of motor, the motor is cause additional loss, followed by mechanical vibration, noise and harmonic overvoltage. When the harmonic current of the motor increases, increasing the magnetic saturation of the motor, it caused the increase of the additional loss of the motor and fever, than simply caused by harmonic itself much more loss and fever. Device for rotary motor, compared with sine magnetization, harmonic can increase the amount of noise. Harmonic sources, such as five times and seven times in the motor load system, can produce six harmonic frequency of mechanical vibration. Mechanical vibration is caused by the vibration of the torque, the torque vibration is caused by harmonic current and fundamental wave frequency magnetic field, if the mechanical resonance frequency and electric excitation frequency, resonance occur, resulting in very high mechanical stress, lead to the risk of mechanical damage. 4, switch, like other devices, harmonic current will cause additional temperature switch outside and lower the fundamental wave current load capacity. Temperature rise for some insulation components will reduce its service life. 5, computer and part of electrical and electronic devices, such as programmable controller (PLC), usually require total harmonic voltage distortion (THD) is less than 5%, and the individual harmonic voltage distortion rate lower than 3%, the higher the amount of distortion can cause misoperation control equipment, which led to the suspension of production or operation, caused large economic loss.
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