APF active power filters

Product introduction:

      In the face of severe power harmonic pollution, active power filters are the most effective tool to improve power quality. The active power filter is a new type of special equipment for power harmonic control , which is developed by using modern power electronic technology and digital signal processing technology based on high-speed DSP processing devices. The active power filter is equivalent to a harmonic current generator, which tracks the harmonic component in the harmonic current, and generates the harmonic current with the same amplitude and inverse phase.

    The active power filter is composed of two parts: command current calculation circuit and compensation current generation circuit. The command current calculation circuit detects the current in the circuit in real time, converts the analog current signal into a digital signal, and sends it to a high-speed digital processor (DSP) to process the signal, separating harmonics and fundamental currents, and the command current is thus obtained. Through the current tracking control circuit and drive circuit, the drive pulse is sent to the compensation current generating circuit in the form of a pulse width modulation (PWM) signal to drive the IGBT and IPM power module, which generates the compensation current with the same amplitude and opposite polarity as the harmonic current. The current is injected into the power grid to compensate or offset the harmonic currents, and actively eliminate the power harmonics, so as to realize the dynamic, fast and thorough treatment of the power harmonics.

Product features:

         Compared with traditional passive filters, active filters have the following outstanding advantages:

1. The harmonic filtering rate is high, and the harmonic impedance performance is not affected by the system impedance.

2. Dynamic compensation can compensate harmonics with varying frequency，magnitude and reactive power, and has a very fast response speed to the change of compensation object.

3. Harmonics and reactive power can be compensated at the same time. The magnitude of reactive power compensation can be adjusted continuously, and no energy storage components are required when compensating reactive power.

4. The energy storage element capacity required for harmonic compensation is small. When the current of the compensation object is too large, the active power filter will not overload and can compensate normally.

5. The device is not greatly affected by the impedance of the grid, and it is not easy to cause series and parallel resonance with the impedance of the grid, and the change of the system structure will not affect the treatment effect.

6. It can track the change of the grid frequency, and the compensation performance is not affected by the change of the grid frequency. It can compensate a harmonic and a reactive power source individually, and it can also compensate multiple harmonics and reactive power sources intensively.

Application fields: