IDC harmonic control solutions

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PM series precision power distribution cabinet
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Description

Harmonic pollution

    When the sine wave voltage is applied to the non-linear circuit, the current becomes non-sinusoidal, non-sinusoidal current produces a voltage drop on the grid impedance causes the voltage waveform becomes non-sinusoidal. Non-sinusoidal Fourier series decomposition, the same frequency and power frequency component called the fundamental frequency is greater than the fundamental components are called harmonics.


    Now widely used in most of the load is non-linear, such as rectifiers, inverter, UPS, elevators, air-conditioning, the energy-saving lamp (fluorescent lamp), copiers, household appliances, etc., these non-linear load will produce a lot of harmonic currents and injected into the grid, the grid voltage distortion, this harmonic "pollution" grid and the user will produce serious harm.

    In addition, impact resistance, fluctuating load, such as electric arc furnaces, welding equipment in operation will not only produce large amounts of high-order harmonics, and cause voltage fluctuations, flicker and unbalanced three-phase power quality problems, endangering the safety of the power grid operation.

 

Harmonics may cause the following problems

Ø increase the line loss, the cable overheating, insulation aging, reduce the power efficiency.

Ø the capacitor overload fever, speed-up capacitor aging or breakdown.

Ø protection device malfunction or refuse to move, led to a regional blackout.

Øcaused by grid resonance.

Ø motor efficiency and uptime, resulting in vibration and noise, shorten motor life.

Ødamage to sensitive equipment in the power grid.

Øvariety of measuring instruments of the power system to produce errors.

Ø interfere with communications, electronic equipment; caused by the failure or malfunction of the control system.

Øzero sequence harmonic neutral current is too large, resulting in neutral heat or even fire.

 

     Grid nonlinear, volatility, unbalanced load increasing, the to inject large number of harmonics and reactive power impact, energy saving and improve power quality, increasing demand on the utility grid. On the one hand, the power grid in order to reduce line loss to improve the quality of the supply voltage for the purpose of the application of the parallel capacitance compensation is increasingly widespread, but a wide range of application of parallel capacitance harmonic amplification phenomenon more common, exacerbated by the effects of harmonics and deteriorated power quality , increased power loss; other hand, with the popularization and application of the computer as the representative of a large number of sensitive equipment on the public grid power quality have become increasingly demanding.

 

    Now widely used in most of the load is nonlinear, such as the rectifier, inverter, electric arc furnaces, welding equipment, UPS, elevators, air-conditioning, the energy-saving lamp (fluorescent lamp), copiers, etc., and these non-linear load will produce a lot of harmonic current and injected into the grid, the grid voltage distortion, such harmonic "pollution" interested in serious harm to the grid and the user. In addition, the impact, the volatility of the load, such as electric arc furnaces, welding equipment in the operation will not only produce large amounts of high-order harmonics, and can cause voltage fluctuations, flicker and unbalanced three-phase power quality problems, endangering the safety of the grid operation.

 

    The traditional harmonic suppression and reactive power compensation method is passive filtering techniques, that the use of passive components such as power capacitors and filter reactance passive filter. In recent years, the IGBT technology as the representative of the active power filter (APF) began large-scale applications.

 

    Compared with the passive filter, APF response speed is fast, high controllability can track each harmonic compensation, dynamic reactive power to generate the desired load change, APF also has the characteristics from the system, no harmonic dangerous wave amplification, small size, light weight and other prominent advantages, and thus has become an important means of power harmonic suppression and reactive power compensation.

 

    APF is based on current sensing and current injection technology High Power Electronics Equipment. The working principle is: the load current waveform through real-time detection, the need to compensate for harmonic current component, and the reverse, by controlling the triggering of the IGBT, the reverse current is injected into the power supply system, and was filtered off (offset) harmonic function, thereby enhancing the safety and reliability of the electrical system, to achieve the purpose of energy efficiency.

 

 

Governance ago:
   

Voltage waveform

Power factor curve

After treatment:

 

   

 

The before filtering system sedan harmonic current and voltage waveform record:

Filtered sedan harmonic current and voltage waveform record:

Single-phase current harmonic control before

Single-phase current harmonic control