The document discusses active harmonic compensation (AHC) systems used to improve power quality in industrial plants affected by nonlinear loads. It notes that traditional passive filters have drawbacks, while AHCs can actively control harmonic and reactive currents. The summary describes the key components of an AHC system, including a closed-loop control system that detects harmonic currents and generates compensating currents using a PWM inverter. It states that while AHCs provide advantages over passive filters, their higher material costs have limited market adoption.

1. 10/20/2016 2:12:02 PM

2. ATHUL RAJ
ruathul@gmail.com

4. HISTORY
 The industry and industrial mains passive filters are
traditionally used
 The filter absorb harmonics generated by the non-linear
load.
 PFC capacitor banks to compensate reactive current.
 They have a number of significant drawback,
 They result in new resonances
 Their magnify the other harmonics
 They are affected by harmonic current from other
non-linear load.

5. INTRODUCTION
 An Active harmonic compensator (AHC) can be
used to improve supply quality.
 Load such a arc furnaces with rapid fluctuations of
reactive and active power consumption contribute
the degradation of power supply quality.
 Non sinusoidal current of the non-linear loads to
fluctuation of power consumption.
 Distortion of the supply voltage waveform and
cause voltage fluctuation.

7. Harmonic
reference
Closed
loop
control
PWM
inverter
LCL
circuit
Non linear
load
Linear load
Power supply/grid Industrial plantHarmonic load
current
Harmonic
Compensation
current
AHC

8.  The industrial plant may include different types of
electrical load.
 Linear loads(resistive load, AC machine), non linear load
(arcing devices).
 The AHC has detect the current harmonics to generate
compensate current that cancel the harmonic
component.
 The control of AHC consist of closed loop control.
 This control loop needed regulation of the inverter
current and DC voltage and detection and generation of
compensation current refference.

9. CONTROL SYSTEM
PLL Harmonic
reference
Reactive
power &
flicker
estimation
Voltage
controller
Current
controlle
r
PWM
inverter
LCL circuit
Selectofswitchin
sequence
H.C.C

10.  The current controller sets the output voltage source
inverter for each sampling period of control system.
 The line current has a reference value.
 The voltage controller allows DC voltage at constant value.
 the selection of the switching sequence for every switching
operation of both voltage source inverter
 The PLL is reduces the high ripple frequency
 The reactive current calculated by reactive power and
flicker estimation module of control unit.

12. The use of active mains compensation holds a
number of advantages compared to the passive
 it is easy to size with the application.
 Does not generate resonance.
 Actively controls with both harmonic and
reactive currents.

13.  The AHC have a limited market share mainly due to
high cost
 Due to the large amount of copper and steel used
in the system to increases the material cost.

14. APPLICATIONS
 AHC operates the compensating reactive current at exactly
right moment.
 To voltage changes and distrotions are reduced to safe
value.
 Main applications,
Mitigation of harmonics
Flicker mitigation
Compensation unbalanced current from a welding
machine.

16.  Can develop rectifiers without capacitors
 In future it can operate as highly dynamically controlled
reactive current source
 It will replace PFC capacitors
 It will replace passive filters

17. CONCLUSION
 AHC for industrial networks can be successfully used.
 The non linear loads and consumers with rapid
fluctuations of reactive and active power to improve
supply quality.
 Voltage wave form distortion and the voltage changes
(flicher effect) to stablised with main voltage.
 These all make the application of the power electronics to
improve supply voltage quality in industry.

18.  Akagi,H: new trends in active filters for power
conditioning. “ IEEE Transitions on industry applications
, vol.32, no.6,pp.1313-1322,1996.
 Rumich,e,Kalaschnikow,s,Oberschwingungs-arme
Netzeinspeisung von windkraftanlagen mit hilfe von
aktivmn finterl, E& I 117.JG.(2000,H.2,pp 129-133.)
 Kalachnikov, s., verger,H: a new control strategy for DC
link voltage of a 3 phase bidirectional pwm
rectifier,epe’95,Spain,1995,pp 2558-2562
 The magazine electrical for you, march edition, 2011

19. ANY DOUBTS