Shunt Active Filter for Electrical Pollution Compensation
Main pollution causes
• Reactive currents: Linear loads
AC motors, transformers) connected
to the line grid absorb sinusoidal
reactive current
SAF based solution
• Shunt Active Filter (SAF): Injects currents
in the line grid in order to compensate for
• Load current reactive components
Voltage and current for reactive loads
• Load current harmonic distortions
Iline
Line
Iload
Load
Ifilt
SAF
time [s]
• Current Harmonics: Produced by non linear
loads (power drives, rectifiers,.. all power
electronics in general)
Voltage and current for reactive loads
Detailed Architecture
current
sensor
LINE
NON LINEAR
REACTIVE
LOAD
voltage
sensors
C
I
Boost
Converter
I
V
V
Digital
Controller
V
I
Legend:
time [s]
Problems due to pollution
Additonal power losses in both electrical
distribution system and user’s facility
Line voltage distorsion
Reduction of reliability and efficiency of
other equipements
I
- V: voltage measurement
- I: current measurement
- C: PWM command
Energy
storage
elements
(capacitors)
- Energy flow:
- Measure and
command signal:
Active filter winning features
Smart compensation
• Partial/total harmonic cancellation
• Simple no line dependant tuning via software
parametrization
Safety
• Resonance phenomena are avoided
Recommended power quality standard
should be fulfilled
• Delivered current auto-saturation
SAF Performance
Line voltage and current for perfect compensation
Line and load current waveform
Line and load current FFT
time [s]
time [s]
Frequency [Hz]