Fuzzy logic controller for five-level shunt active power filter under distorted voltage conditions

 ABSTRACT:

In this paper, a five-level inverter is used as a shunt active power filter (APF), taking advantages of the multilevel inverter such as low harmonic distortion and reduced switching losses. It is used to compensate reactive power and eliminate harmonics drawn from a diode rectifier feeding a RL load under distorted voltage conditions. The active power filter control strategy is based on the use of self tuning filters (STF) for reference current generation and a fuzzy logic current controller. The use of STF instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the a-J3 axis without phase locked loop (PLL). This study is divided in two parts. The first one deals with the harmonic isolator which generates the harmonic reference currents. The second part focuses on the generation of the switching pattern of the inverter by using a fuzzy logic controller applied and extended to a five level shunt APF. The MA TLAB Fuzzy Logic Toolbox is used for implementing the fuzzy logic control algorithm. The obtained results show that, the proposed shunt active power filter controller has produced a sinusoidal supply current with low harmonic distortion and in phase with the line voltage.

KEYWORDS:

1.      Active filter

2.      Harmonics isolator

3.      Distorted voltage conditions

4.      Self-tuning filter

5.      Fuzzy logic control and PWM control

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig1.power system configuration

EXPECTED SIMULATION RESULTS:

Fig. 2. Supply voltage Vs waveform

Fig. 3. Supply current Is waveform without filtering.

Fig. 4. Supply current Is waveform with filter.

Fig. 5. Active filter current If

Figure 6. APF output voltage Vab (line to line) for a five-level with

PDPWM

Fig. 7. DC voltage of the condensers Vdc

CONCLUSION:

This paper has discussed the control and performance improvement of a shunt active power filter under distorted voltage conditions, using a fuzzy logic controller for a five level shunt active power filter based on the optimization of the reference current generation and using a modified version of the p-q theory and PDPWM to generate switching signals. Simulation results have shown high performances in reducing harmonics and power factor correction. The use of the Self-tuning filter leads to satisfactory improvements since it perfectly extracts the harmonic currents under distorted conditions. With the fuzzy logic control, the active filter can be adapted easily to more severe constraints, such as unbalanced conditions. In addition, results have demonstrated the major advantages of using STF and fuzzy logic controller in filter control. The Five-level APF provides numerous advantages such as improvement of supply current waveform, less harmonic distortion and possibilities to use it in high power applications. As final conclusion, the obtained results showed that, the proposed active power filter controller have provided a sinusoidal supply current with low harmonic distortion and in phase with the line voltage.

REFERENCES:

[I] H. Akagi, "Trend in active power line conditioners," IEEE Trans Power Electronics, vol.9, pp.263-268, August 1994.

[2] H.-K. Chiang, B.-R. Lin, K.-T. Yang, and K.-W.Wu, "Hybrid active power filter for power quality compensation," IEEE Power Electronics and Drives Systems,voL2, pp.949-954, 2005.

[3] X. Wanfang, L. An, and W. Lina, "Development of hybrid active power filter using intelligent controller, " Autom. Electric Power Syst. Vo1.27, pp.49-52,2003.

[4] O. Vodyakho, T. Kim, S. Kwak, 'Three-level inverter based active power filter for the three-phase, four-wire system," IEEE Power Electronics Specialists Conference, pp. 1874-1880,2008.

[5] G.W. Chang, C.M. Yeh, "Optimization-based strategy for shunt active power filter control under non-ideal supply voltages, " lEE Electric Power Applications, voL152, pp.182-190, March 2005.

Comparison of two compensation control strategies for shunt Active Power Filter

ABSTRACT:

The purpose of this paper is to present a harmonic mitigation using a shunt active filter with accurate harmonic current identification and compensation based on instantaneous active and reactive power theory and a self-tuning filter for the harmonic isolation and a fuzzy hysteresis band technique for the current control. In order to find the best strategy for the power quality improvement, a comparative study has been illustrated. The Analysis and simulation results using Matlab/Simulink confirm the effectiveness and limits of the proposed methods and also show the performances of fuzzy logic control which provides flexibility, high precision and fast response.

KEYWORDS:

1.      Active power filter (APF)

2.      Fuzzy logic control

3.      THD

4.      Harmonic

5.      Hysteresis-band control

6.      Power quality

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure 1. Active Power Filter

 EXPECTED SIMULATION RESULTS:

Figure 2. Harmonic compensation with p-q theory and fuzzy hysteresis band control

Fig 3.Source current's harmonic spectrum (p-q theory)

Figure 4. Harmonic compensation with STF theory and fuzzy hysteresis band control

Figure 5. Source current's harmonic spectrum (STF)

Figure 6. The DC voltage

CONCLUSION:                                                    

In this paper the quality of the energy is improved by using the active filtering. A model of shunt active power filter is illustrate with its control strategy based on the p-q theory concept and a STF using fuzzy logic current control, the developed techniques shown excellent performances in harmonics mitigation and reactive power compensation. The comparative evaluation proved that the STF gives better quality filtering then the conventional p-q theory which is the main objective to be achieved. To confirm the efficiency of this solution and to improve the system response experimental application and others techniques as Neuro-fuzzy control can be developed.

REFERENCES:

[1] H. USMAN, H. HIZAM, M. AMRAN, M. RADZI "Simulation of single-phase shunt active power filter with fuzzy logic control ler for power quality improvement", clean energy and technology, 2013.

[2] A CHAOUI, J-P. GAUBERT, A BOUAFIA, "Experimental validation of new direct power control switching table for shunt active power filter power", conference on Electronics and Applications (EPE), 2013.

[3] R. BELAIDI, M.HATTI, A HADDOUCHE, M. M. LARAFI, "Shunt active power filter connected to a photovoltaic array for compensating harmonics and reactive power simultaneously", 4th international conference on power engineering, energy and electrical drives, may 2013.

[4] B. SINGH, K. AL-HADDAD, A CHANDRA, "A review of active filters for power quality improvement", IEEE transactions on industrial electronics, vol. 46, no. 5, October 1999.

[5] G. W. CHANG, C. M. YEH, "Optimisation-based strategy for shunt active power filter control under non-ideal supply voltages ",lEE proceedings - electric power applications, vol. 152, no. 2, pp. 182,2005.

Hardware Implementation of a Three-Phase Active Filter System with Harmonic Isolation Based on Self-Tuning-Filter

ABSTRACT:

This paper presents the hardware implementation of a new control method based on an improved harmonic isolation for active filter systems. The harmonic generation is based on Self Tuning Filters for the harmonic isolation and on a modulated hysteresis current controller for the current control technique. This active filter is intended for harmonic compensation of a diode rectifier feeding a RL load. The study of the active filter control is divided in two parts. The first part deals with the harmonic isolator which generates the harmonic reference currents and is implemented into a Dspace DS1104 prototyping card. The second part focuses on the generation of the switching pattern of the IGBTs of the inverter by the modulated hysteresis current controller, implemented into an analogue card. The use of Self Tuning Filters instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the α-β axis at high performances, without any Phase Locked Loop. The effectiveness of the new proposed method is verified by computer simulation and validated by experimental study.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig 1. Power system configuration.

EXPECTED SIMULATION RESULTS:

Fig 2. Simulation results for the phase 1 under sinusoidal voltage conditions: (a) load current, (b) supply current after compensation

CONCLUSION:

This paper has discussed the control and performances of a shunt active power filter. The hardware implementation has been performed based on the optimisation of the reference current generation and using a modified version of the p-q theory. The control of the active filter was divided in two parts, the first one realized by the DSPACE system to generate the reference currents and the second one achieved by an analogue card for the switching pattern generation, implementing a modulated hysteresis current controller.

STFs have been introduced in the proposed modified version of the p-q theory instead of classical extraction filters (high pass and/or low pass filters) for both grid voltages and load currents. The use of this filter experimentally leads to satisfactory performances since it extracts the harmonic currents at high performances. For the current controller, we implemented the modulated hysteresis current controller to obtain a fixed switching frequency for the IGBT’s.

The simulation and the experimental results have demonstrated and conforted the effectiveness of using STF and modulated hysteresis current controller in the filter control. In conclusion, the proposed control for shunt active power filter is effective in installation on an actual power system.  

REFERENCES:

[1] J. C. Das,” Passive filters- Potentialities and limitations” IEEETransactions on industry applications, vol. 40, pp. 345-362 (2004).

[2] H. Akagi, “Active and hybrid filters for power conditioning” IEEE International Symposium on Indsutrial Electronics, vol 1, (2000).

[3] P. Jintakosonwit, H. Fujita and H. Akagi,” Control and performance of a fully-digital-controlled shunt active filter for installation on a power distribution system” IEEE-Transactions on power electronics, vol. 17, pp. 323-334 (2002).

[4] M. P. Kazmierkowski and L. Malesani, “Current control techniques for three-phase voltage source PWM converters: a survey” IEEE Trans. Ind. Elect. vol.45, n°5, pp. 691-703 (1998).

[5] H. Akagi, Y. Kanazawa and A. Nabae “Generalized theory of the instantaneous reactive power in three-phase circuits” , Proceeding International power electronics conference. Tokyo, Japan, PP. 1375-1386, (1983).

Design and Implementation of Sliding Mode and PI Controllers based Control for Three Phase Shunt Active Power Filter

ABSTRACT:

This paper presents a simulation and experimental comparative study of Sliding Mode Controller (SMC) and Proportional Integral (PI) regulator based the control of the DC bus voltage of three phase shunt Active Power Filter (APF). The capacitor that feeds the active filter plays the role of a voltage source. This tension must be kept constant, so as not to degrade the filter performances, and not to exceed the voltage of semiconductors. The main cause of the variation of this voltage is the change in the pollutant load, which creates an active power exchange with the network (if the inverter provides power active, then the average voltage across the capacitor will decrease and if the inverter consumes power active, then the average voltage across the capacitor will increase). The algorithm used to identify the reference currents is based on the Self Tuning Filter (STF). This study was verified experimentally, using a hardware prototype based on dSPACE-1104.

KEYWORDS:

1.      Active Power Filter (APF)

2.       Sliding Mode Controller (SMC)

3.      Self Tuning Filter (STF)

4.       Proportional Integral (PI) Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Basic compensation principle of the shunt APF.

 EXPECTED SIMULATION RESULTS:

Fig.2. Simulation APF with PI: capacitor voltage Vdc (V); source current iS (A) and load current iL(A).

Fig.3. Simulation APF with SMC: capacitor voltage V_dc (V); source current i_S (A) and load current i_L(A).

CONCLUSION:

 Two different control strategies for a three-phase shunt active power filter employing a digital signal processor DSP were presented in this paper. The first is based on sliding mode control SMC and the second uses a single proportional-integral controller PI. These controllers are used in order to regulate the DC voltage of the three phase shunt active power filter and improving the dynamical performances. Several tests have been performed in order to prove the efficiency of the type of the control. The results obtained by simulations and Experimental, show that the SMC controller offers better performances than the PI.

REFERENCES:

[1] Das J.C (2004), “Passive filters- Potentialities and limitations”, IEEE-Transactions on industry applications; 40(1): 232– 241.

[2] Wei Zhao, An Luo, Ke Peng, Xia Deng “Current control for a shunt hybrid active power filter using recursive integral PI” Journal of Control Theory and Applications, February 2009, Volume 7, Issue 1, 77-80.

[3] Mekri F, Machmoum M, Mazari B and Ahmed N A.( 2007) “Determination of voltage references for series active pow er filter based on a robust PLL system”. In: IEEE International Symposium on Industrial Electronics. p.473 – 78.

[4] Karimi S. ,Poure P. ,Saadate S. , Gholipour E. (2008), ‘FPGA-based fully digital controller for three-phase shunt active filters’, International Journal of Electronics, 95( 8), 805–818.

[5] Abdusalam M, Poure P, Saadate S. (2008) “Study and experimental validation of harmonic isolation based on Self -Tuning-Filter for threephase active filter”, In: IEEE International Symposium on Industrial Electronics,166 – 71.

Control of the Shunt Active Power Filter under Non- Ideal Grid Voltage and Unbalanced Load Conditions

ABSTRACT:

In this study a new method is proposed in order to improve the harmonic suppression efficiency of Active Power Filter for the problems caused by the distorted and unbalanced voltages with unbalanced load currents in control strategy. The proposed control method gives an adequate compensating current reference even for non ideal voltage and unbalanced current conditions. The results of simulation study are presented to verify the effectiveness of the proposed control technique in this study.

KEYWORDS:

1.      Active Power Filter

2.      Park Transformation

3.      Clark Transformation

4.       Self Tuning Filter

5.      Unbalanced Load Currents and Voltages

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Block diagram of the APF

 EXPECTED SIMULATION RESULTS:

Fig. 2. Three phase unbalanced and distorted (non-ideal) grid voltage

Fig. 3. Unbalanced varying load current under non-ideal voltage condition.

Fig. 4. Voltage waveforms, a-) Three phase unbalanced and distorted grid voltages, b-) Grid voltages after transformation to α-β ( at the input of STF), c-) The obtained balanced and undistorted two phase voltage waveforms (at the output of STF), d-) The obtained balanced and undistorted three phase voltage waveforms (at the input of PLL).

Fig. 5. DC-link terminal voltage with the proposed control method

Fig. 6. Three phase converter currents

Fig. 7. Grid current after filtering by proposed control method under distorted and un-balanced grid voltage with unbalanced load conditions

CONCLUSION:

In this paper, we have considered to design a control method in order to generate correct reference current signal to satisfy the requirements of harmonic suppressing and reactive power compensation for the unbalanced nonlinear loads combination under case of non-ideal grid voltage conditions. In the propose method, the distorted and unbalanced voltages first processed by using Self Tuning Filter to determine the correct angular positions. Then second STF is used to extract balanced load current waveforms after obtaining the fundamental and harmonic components of instantaneous currents by using park transformation. In this study, additional low-pass or high-pass filter is not used to extract harmonic components from the fundamental. The simulation studies shows that the proposed control technique gives an adequate compensating current references.

REFERENCES 

[1] W. M. Grady, S. Santoso, "Understanding power system harmonics", IEEE Power Eng., Rev. 21, pp. 8-11.

[2] B. Singh, K. Al-Haddad, K, A. Chandra, "A review of active filters for power quality improvement", IEEE Transaction on Industrial Electronics., vol. 46, no. 5, pp. 960–971, 1999.

[3] N. Mariun, A. Alam, S. Mahmod, H. Hizam, "Review of control strategies for power quality conditioners", PECon 2004, Power and Energy Conference, vol., no., pp. 109- 115, 29-30 Nov. 2004.

[4] H. S. Song, “Control scheme for PWM converter and phase angle estimation algorithm under voltage unbalance and/or sag condition”, Ph.D. thesis in Electronic and Electrical Engineering. South Korea, 2000.

[5] M. Abdusalam, P. Poure, S. Saadate, “A New Control Scheme of Hybrid Active Filter Using Self-Tuning-Filter,” POWERENG 2007 International Conference on Power Engineering, Energy and Electrical Drives, 2007, vol., no., pp.35-40, 12-14 April 2007.