The power distribution system of drilling platform has been powered by generators, and has been powered by electricity. Now, the power supply is provided by the power grid. Because of the large amount of harmonic currents generated by DC motor and frequency conversion motor, dynamic reactive power compensation and harmonic control are needed. The frequent start and stop of the motor causes great interference to the power grid

The main load equipment is the frequency converter. Because of the large harmonic current (especially the 5 and 7 harmonics) produced by the load, the voltage and current of the system will be distorted, which will affect the normal operation and safety production of the equipment. The input side of the inverter is a nonlinear rectifier circuit, which affects the waveform of the power supply. The output side voltage, current, non sinusoidal or incomplete sine wave are rich in harmonics.

Container terminal loads are mostly cranes, which are impulse loads, with large amplitude and obvious voltage drop. Especially during the whole process, flickering and voltage collapse are very obvious. The power factor of the motor is very low during starting up. This impulse reactive power will make the grid voltage fluctuate violently, even even the users connected to the same power grid can not work normally.

In the port industry, the loading and unloading bridges and the belt conveyer are widely adopted by AC frequency converter and DC rectifier. This kind of load is a typical nonlinear load...

Through the effective protection of the harmonic control after the safe use of transformers, power distribution cabinets, and equipment, prolong the service life of the equipment; the utility grid device to produce additional power consumption is reduced; improve the efficiency of electricity charging equipment, battery charging protection in the process of safety; greatly reduces the harmonic current into the power grid, to avoid the interference of adjacent power supply system.

After the active filter is put into operation, the total current distortion rate is reduced to 0.75%. The quality of the power grid has been greatly improved, which effectively protects the normal operation of the equipment.

The total current distortion rate is reduced to 4.78%, the distortion rate of each subharmonic is within 1.5%, and the waveform of the non sinusoidal wave before the treatment is a sine wave. It can be seen that after the input of the filter, the harmonic of the system has been well suppressed, improving the reliability of the power supply system, eliminating the hidden trouble of the influence of the system harmonic on the communication system, and receiving good results.