Power Protection Relays

Active Power Filter

Active Power Filter(APF Harmonic Correction)


BUENO-APF active power filter (hereinafter referred to as BUENO-APF), a new solution for harmonic control based on dynamic harmonic elimination technologies, can eliminate the grid harmonic with help of the advanced dynamic real-time tracking and compensation technologies. It can monitor the current waveform produced by the nonlinear load in real time, separate the harmonic component, and inject the harmonic currents of corresponding value and opposite directions to the grid, achieving the harmonic elimination function. All the indexes on technical performance of the BUENO-APF have reached the equal level of the equivalent products both at home and abroad and both the cost and the technology have achieved revolutionary breakthrough. Thanks to the new process design, the size is dramatically reduced, saving the precious space in the machine room and significantly lowering the threshold for the enterprise user to use the active filter technology.

BUENO-APF is a power electronic device of large power based on the current detection and current injection techniques. Its working principle is as follows: The waveform of the load current shall be detected in real time to obtain the harmonic current component to be compensated, which then shall be converted in direction, and the IGBT triggering shall be controlled to inject the reversed current to the power supply system, realizing the function of harmonic elimination (offset) and further improving the safety and reliability of the electrical system as well as achieving the goals of energy efficiency.

BUENO-APF can be viewed as a current source where a harmonic current is provided at the main connection and the harmonic current is opposite in direction to the total harmonic current produced by the nonlinear load. The grid is still running with the fundamental current before the BUENO-APF is connected to the load.

Since the compensation current of BUENO-APF is regular, the compensation quality is independent from the network impedance and the power source voltage distortion produced by voltage resonance, dip or flicker. The internal definition of the compensation current is designed to protect the equipment from damaged by over-current, and other loads connected to the power source are free from impact by parallel with the active filter. These features are applied especially to the pulse control system.

Product features:

Real-time monitoring

BUENO-APF can monitor the energy quality of the distribution system, through which, the followings can be read in real time: THDi and THDu on the grid and/or load sides, the phase current values, and the effect waveform diagram before/after compensation as well as the compensation current values generated by BUENO-APF and the waveform and other data on energy quality. The operation is simple with easy data reading.

System setting

In the monitoring system of BUENO-APF, the followings can be set: the working mode, date, CT ratio and the compensation mode etc. where the password shall be entered to ensure the independent and safe running. All the setting options shall be recorded and kept in the system.

Background monitoring

BUENO-APF is designed with RS485 and the network interfaces so that it can communicate with the computer via data or network lines. The special background monitoring software can be installed in the computer terminal and then the remote operation and control are available for BUENO-APF, offering huge convenience to its running.

Technical features of BUENO-APF

All the components are imported quality brands to ensure the quality;

The 3DSP+CPLD totally digital control mode is used to achieve high stability and reliability and eliminate the harmonic accurately;

It can filter dynamically the 2nd~50th harmonic in real time or select optionally the typical characteristic harmonics of various orders present in the grid phase and zero lines;

Many compensation functions such as harmonic compensation, Var compensation and imbalance compensation etc are provided so that the user can select the desired one;

For the APF of three phases and four lines, its capacity to filter the harmonic on the zero line is as three times as that on the phase lines, which is designed for the harmonic over-load on the zero line due to excessive single-phase loads (The 3rd harmonic current on the zero line can reach as three times as that on the phase line due to equal phase position and superimposition) and the imbalanced phases.

The operation is simple thanks to the friendly operation and display man-machine interfaces, and the data and curves can be displayed in real time;

The modular cabinet design is adopted for flexible assembly (Rack and wall-mounted types);

Various effective protection measures are provided to protect the distribution system and the internal equipment from any adverse impact in normal and/or abnormal conditions, including various protection functions (over-load, over/under-voltage, internal faults etc.). It can automatically limit the compensation current in a reasonable manner according to the load variation so that the device will be free from over-current and it can avoid over-compensation while filtering. In addition, the APF high-frequency carrier will not feed back to the grid so that it will not result in any interference on the power supply system and the system equipment.

It is designed with RS485 interface for communication with PC;

It is independent from the impedance of the grid system and thus free from impact of the impedance of the grid system and no resonance and harmonic voltage enlargement will occur. Obviously it is designed with good safety;

It is designed with good extension performance and several APFs can be applied in shunt.

Technical Specifications:

Harmonic Correction

Rated compensation capacity: 25A,35A,50A,60A,75A,100A,Modularized,Free parallel extended capacity


Work Voltage(V):          380V  -40%~+20%

Work Frequency:             50/60Hz  +/-10%

Performance Index

Machine Efficiency:           >97%

Filter Ability:                   THDi<5%

Filter Range:                  2~50 times

Response Time:             <300μs

Full Response Time:        <10ms

Neutral Line Filter Ability:   3 times as Phase Line

IGBT Frequency:               20kHz

Self-diagnosis and Protection:  Yes

Communication Interface:    RS232,  RS485  ,Ethernet

Protocol:                         Modbus

Mount:                           Wall or Rack

Protection Grade:            IP20

Surge Protection:            20kA

Parallel Nodes:               6 pieces

CT Transformer:             300/5~4000/5

Environment Condition

Work Temperature:         0℃~50℃

Storage Temperature:      -20℃~70℃

Humidity:                      95%,No condensing

Altitude:            ≤1500m,1500~4000m,Refer to GB/T3859.2,Every 100m increase,1% Power Reduction


Commercial Buildings, UPS, Computer Center, Elevator, Escalator, Cableways, Residential Buildings, Hospitals, TV and Broadcasting Stations, Air Conditioning System, Energy-saving Lights, Subways, Oil and Gas Plants, Electric Railways, New Energy(solar,wind farm), Steel Plant, Cement Plant, Water Treatment, Automobile Factory, Machinery Factory, Ship Yard and so on.




* You can also contact us for a quote by E-mail: sales@buenoptic.net

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