Abstract
The most important part of the shunt active power
filters is generating of gate signal for Voltage Source Inverters (VSI). In this
paper the proposed Space Vector Pulse Width Modulation (SVPWM) is implemented
in a closed loop control system for a shunt active power filter. The reference harmonic
components are extracted from the sensed nonlinear load currents by applying
the Synchronous Reference Frame (SRF) theory, where a three-phase thyristor
bridge rectifier with R-L load is taken as the nonlinear load. The switching
control algorithms of the proposed SVPWM would be generating appropriate
switching gates to the voltage source inverter. The shunt active power filter
generates the actual compensating harmonic current based on the switching gates
provided by the controller. For showing the performance of proposed method a typical
system has been simulated by MATLAB/SIMULINK. The proposed active power filter
is able to improve about 30.18% of the total harmonic distortion (THD) for the
distorted line current caused by an uncontrolled rectifier as the nonlinear
load and to meet IEEE 519 standard recommendations on harmonics level.
Keywords
1.
Power Quality
2.
Shunt Active
Power Filter
3.
Synchronous
Reference Frame Theory
4.
Space Vector
Pulse Width Modulation (SVPWM).
Block Diagram
Fig 1. Block
diagram of proposed Shunt active power filter for a 3phase 3 wire system
Fig 1. Block
diagram of proposed Shunt active power filter for a 3phase 3 wire system
Simulation Results:
Fig
2. Three phase voltage and load currents for before Compensation-simulation
results:(a) a-phase voltage, volts, (b) a-phase load current, Amps
Fig 3. %THD source current before compensation
Fig
4. Reference compensation-(a) a-phase compensation currents, Amps (b) b-phase
compensation currents, Amps (c) c-phase compensation current, Amps.
Fig
5. %THD source current after compensation
Fig
6. Source Voltages and Currents in three phases after compensation-(a)a-phase
source voltage, (b)a-phase source current
Conclusion
In
this paper, a novel simplified control method, which is suitable for digital
control realization, for the active power filter using SVPWM is proposed. The
objectives of this project have been achieved by reducing the harmonic
components that exist in a power system with a chosen nonlinear load. This most
recent aimed on the one hand to prove the effectiveness of the SVPWM in the
contribution in the switching power losses reduction in shunt active filter.
The proposed closed loop filtering control system mainly consists of the
harmonics isolator, the hysteresis tolerance comparators conjunction with the
space vector pulse width modulation controller and the active power filter. The
combination of these components enables the closed loop control system to be
implemented. The proposed system is able to compensate the harmonics caused by
a three phase uncontrolled diode rectifier and it provides positive results by
reducing the percentage of THD of the line current. The shunt active filter is
found effective to meet IEEE 519 standard recommendations on harmonics
level.
References
[1] Singh.B,
A1-Haddad.K, Chandra.A, “Review of active filters for power quality
improvement”, IEEE Trans. Ind. Electron.,(46), 5, Oct, 1999, pp. 960-971
[2] E1-Habrouk.
M, Darwish. M. K, Mehta. P, “Active power filters-A review,” Proc. IEE-Elect.
Power Applicat., vol. 147, no. 5, Sept. 2000, pp. 403-413.
[3] Akagi, H.,
“New trends in active filters for power conditioning,” IEEE Trans. On Industry
Applications, (32), 6, Nov-Dec, 1996, pp. 1312-1322
[4] Peng
Fangzheng, “Application issues of active power filters,” IEEE Industry
Applications Magazine, v 4, n 5, Sep-Oct, 1998, pp. 21-30
[5] Akagi.H,
Kanazawa.Y, and Nabae.A, “Instantaneous reactive power compensators comprising
switching device without energy storage components,” IEEE Trans. on Industry
Applications, (20), 3, 1984, pp. 625-630.
