High-voltage Active Electric Power Filter is an important trend to use active filter to restrain harmonic. This kind of filter can track and compensate the harmonic which will affect and change its frequency and amplitude, and the compensation can not be affect by grid impedance, so peoples pay more attention to the filter. Now its applied in Europe and America widely and perfect effect is gained .
Fundamental
APF detects harmonic current from compensation object, Compensator produces a same size harmonic compensation current with a opposite polarity to eliminate harmonic current, then a grid current only contains fundamental component.
Main switch parts: IGBT; Control system: DSP+CPLD+FPGA; Control theory: instantaneous reactive power theory.

1  Functions and characteristics

1.1 Real time tracking, dynamical compensation
It tracks change of harmonic automatically with controllable properties, and rapid respondence. Its compensation capability cannot be affected by undulation of grid frequency, its filter properties will never be affect by system impedance and eliminate danger of resonance between system impedance and APF
1.2  Compensation for harmonic and reactor power simultaneously
One APF has many functions. It not only can compensate harmonic, but also can compensate reactive and restrain voltage flashover. It can make compensation for single harmonic and reactor source as well as it can make compensation for multiple harmonics and reactor source collectively. It is unnecessary for energy storing parts when it is making compensation for reactor source.
1.3  IGBT Hi-frequency switch convertor
Full bridge PWM convertor is adopted to generate compensation current. A third generation IGBT is adopted to be a drive part. It will operate at high frequency mode. The IGBT part, drive and protection circuit are integrated together to be a power unit to make convertor with small volume, high efficiency, high reliability properties.
1.4  Tracking current control
Current measuring and detecting technique is adopted based on instantaneous reactive power to measure and detect current. The APF will carry out to compensate harmonic current dynamically. The APF can never make over load during compensating in whole hog because of current control.
1.5  DSP Monitoring intelligently
DSP ensures accuracy and validity during harmonic detecting and compensating because of high-speed measuring, detecting and computing. There are many functions existed, e.g., Monitoring intelligently, flexible operation, clear running parameter and operation status, fault diagnosis automatically, etc. A communication interface can be extended to be used for PC monitoring.High-frequency active electric power filter can be applied widely in power distributor for electric power factory, commercial and department groups, e.g., factory which applies full wave DC power supply and inverter quipment,electric power system, petrifaction enterprise, electrization railway, metallurgy factory, high-rise buildings, UPS/generator unit, precision electronics enterprise, stock exchange power distribution power system, airport/seaport spare power supply, medical treatment imaging system, etc.
Harmonic: electric arc furace, electric power engine, SCR convertor, inverter, TV, air conditioner, etc.
Fluctuating voltage: electric welding machine, punch, crane, elevator, wind power generator, X-ray machine, etc.
Flashover: electric welding equipment, crane, elevator, wind power generator, punch, electric saw, etc.
a three phase asymmetry: lighting equipment, inductive furnace, electric welding machine, electric resistance furnace, quarts melting furnace, etc.
Reactive power: asynchronous motor, transformer, convertor, inverter, inductive furnace, lighting equipment, etc.

2  The implementation of standards

GB/T1454993 Power Quality: Harmonic common power grid
GB/T155761995 Low-voltage static Lian reactive power installations of technical conditions
GB/T7625.11998 Low-voltage electrical and electronic products issued by the harmonic current limits
Q/SP001-2005 APF technical conditions

3  Technical Parameters

Power supply voltage     380V,+10%~-15%
Power supply frequency  50Hz±5%
Power supply phases3-phase, 3-wire or 3-phase, 4-wire
Current transformer(sensor)   /5A
Harmonic compensation times  3-phase, 3-wire 5~25 times; 3-phase, 4-wire 2~25 times
Dynamical compensation response time  100ms
Compensation capacity:  Full compensation within equipment compensation capacity; Max output capacity compensation over equipment compensation capacity
Protection:  AC over-voltage, under-voltage, DC over-voltage, IGBT over-current, APF over-heating
Cooling mode:  Ventilator cooling
Efficiency: >95%
Operation and display: LED & LCD display, digitals, menus, and figures display function, easy to operate, monitor and make maintenance
Running circumstance temperature: -10~+40
Relative humidity: <90%25
Insulated protection level: IP20
Structure: Vertical panel mode, cable incoming and output under panel