A Comparative Study of Different Multilevel Converter Topologies for High Power Photovoltaic Applications

ABSTRACT:

This paper investigates the modern topology of multilevel converters, which are suitable for use in high power photovoltaic applications with the focus on achieving lower total harmonic distortion and better efficiency. Multilevel converters offer several advantages compared to conventional types. Multilevel converters provide high quality output while using the low switching frequency. It affects the switching losses, size of semiconductor switches and harmonic filters. This research investigates various topologies of multilevel converter for high power photovoltaic applications and compares their THD, efficiency, number of required semiconductors and other important characteristics. All topologies are simulated using MATLAB/Simulink in the same operating conditions. Finally, the more suitable multilevel topology is selected with respect to the simulation results.

KEYWORDS:

1.      Photovoltaic

2.      Multilevel converter

3.      Qualitative study

4.      High power application

SOFTWARE: MATLAB/SIMULINK

DIFFERENT TOPOLOGIES:

Fig 1: a) NPC b) Capacitor clamped c) Cascade d) Z-source e) Quasi Z-source f) Hybrid

EXPECTED SIMULATION RESULTS:

Fig.2. Three level NPC inverter voltage and current waveforms.

Fig. 3. Three level Capacitor clamped voltage and current waveforms.

Fig. 4. Voltage and current waveforms of three level cascaded inverter.

Fig.5. Voltage and current waveforms of three level Z source inverter.

Fig.6. Voltage and current waveforms of three level Quasi Z source.

Fig. 7. Voltage and current waveforms of three level hybrid model.

CONCLUSION:

The price analysis of the converter shows that multilevel converters are more economic than conventional types in the case of medium and high power applications. In This research, different multilevel converter topologies have been investigated and compared in order to find the most suitable topology, which is appropriate to use in the PV applications. Six multilevel topologies, which were proposed in the literature, have been investigated. The investigation was done via quantitative and qualitative study. In quantitative study, important output parameters of proposed multilevel topologies were evaluated using Matlab/Simulink at the same operating point. Also, a qualitative analysis has been performed to investigate some advantages and disadvantages of each topology, which cannot be considered in the simulation. The results prove that quasi Z-source converter has better performance in comparison with other types.

REFERENCES:

[1]   Nabae, I. Takahashi and H. Akagi, “A new neutral point clamped PWM inverter”, IEEE Trans. Ind. Appl., IA-17 (5) 518–523, 1981.

[2]   T. A. Meynard, H. Foch, P. Thomas, J. Couralt, R. Jakob, and m. Naherstaedt, “Multicel converters: Basic consepts and industry application”, IEEE Trans. Ind. Electron., 49 (5), 955-964, 2002.

[3]   M. F. Escalante, J. C. Vannier, and A. Arzande, “Flying capacitor multilevel inverters and DTC motor drive applications”, IEEE Trans. Ind. Elect., 49 (4), 809–815, 2002.

[4]   S. S. Fazel, S. Bernet, D. Krug and K. Jalili,“Design and comparison of 4 kV Neutral-pointclamped, flying capacitor and series-connectd H-bridge multilevel converters”, IEEE Trans. Ind. Appl., 43(4), 1032-1040, 2007.

[5]   J. V. Núñez, “Multilevel Topologies: Can New Inverters Improve Solar Farm Output? ” Solar industry journal, 5, 12, 2013.

A Synchronous Generator Based Diesel-PV Hybrid Micro-grid with Power Quality Controller

ABSTRACT:

This paper presents an isolated microgrid, with synchronous generator(SG) based diesel generation (DG) system in combination with solar photo-voltaic(PV). The DG supplies power to the load directly, and a battery supported voltage source converter (VSC) is connected in shunt at point of common coupling (PCC). The PV array is connected at DC-link of the VSC through a boost converter. A high order optimization based adaptive filter control scheme is used for maintaining the quality of PCC voltages and source currents. This controller makes the waveform free of distortion, removes errors due to unbalances, corrects the power factor and makes the source current smooth sinusoidal, irrespective of the nature of load. MATLAB/Simulink based simulation results demonstrate satisfactory performance of the given system.

KEYWORDS:

1.      Battery

2.      Diesel generator

3.      LMF

4.      Power quality

5.      PV

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1 System model

EXPECTED SIMULATION RESULTS:

Fig. 2 Steady State Response of DG-PV micro-grid

Fig. 3 Dynamic Response of DG-PV micro-grid

CONCLUSION:

An isolated SG based DG and PV hybrid micro-grid has been presented here, with a battery suppported VSC connected at PCC. Three-phase adaptive control is used for power quality improvement through VSC. The given system and control have been simulated in MATLAB/Simulink environment and results demonstrate their satisfactory performance in both steady state and dynamic conditions.

REFERENCES:

[1] G. Shafiullah et al., “Meeting energy demand and global warming by integrating renewable energy into the grid,” in 22nd Australasian Universities Power Engg. Conf. (AUPEC), pp. 1–7, Bali, 2012.

[2] M. Milligan et al., “Alternatives No More: Wind and Solar Power Are Mainstays of a Clean, Reliable, Affordable Grid,” IEEE Power & Energy Mag., vol. 13, no. 6, pp. 78–87, Nov.-Dec. 2015.

[3] L. Partain and L. Fraas, “Displacing California’s coal and nuclear generation with solar PV and wind by 2022 using vehicle-to-grid energy storage,” IEEE Photovoltaic Specialist Conf., pp. 1–6, LA, 2015.

[4] Daniel E. Olivares et al., “Trends in Microgrid Control,” in 2015 IEEE Trans. Smart Grid, vol. 5, no.4, pp. 1905–1919, July, 2014.

[5] Z. Zavody, “The grid challenges for renewable energy An overview and some priorities,” IET Seminar on Integrating Renewable Energy to the Grid, pp. 1–24, London 2014.

Real Time Control of an Active Power Filter under Distorted Voltage Condition

ABSTRACT:

This paper, presents three phase shunt active filter under distorted voltage condition, the active power filter control is based on the use of self-tuning filter (STF) for reference current generation and on space vector PWM for generation of pulses. The dc capacitor voltage is controlled by a classical PI controller. The diode rectifier feed RL load is taken as a nonlinear load. The self-tuning filter allows extracting directly the voltage and current fundamental components in the axis without phase locked loop (PLL) under distorted voltage condition. The experiment analysis is made based on working under distorted voltage condition, and the total harmonic distortion of source current after compensation .Self tuning filter based extraction technique is good under distorted voltage conditions. The total harmonic distortion (THD) of source current is fully reduced. The effectiveness of the method is theoretically studied and verified by experimentation.

KEYWORDS:

1.      active power filters,

2.      dSPACE1104,

3.      real time

4.      STF

5.      SVM

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure 1. Active Power Filter

 EXPECTED SIMULATION RESULTS:

Figure 2. The source voltage

Figure 3. The load current

Figure 4. Source current

Figure 5. Filter current and its reference

Figure 6. The DC voltage

Figure 7. Load current's harmonic spectrum

Figure 8. Source current's harmonic spectrum

CONCLUSION:

A modified pq theory control technique applied to a three-phase Shunt Power Filter is proposed. The appropriate control strategy for removing harmonics caused by non-linear loads is developed. The main advantage of the proposed method is its simplicity (no PLL circuit needed) and its efficiency in non-ideal voltage condition. The use of SVPWM method allows to the inverter to fellow its reference accurately which increase the performance of the active filter. The experiment results show the efficiency of the proposed method in terms of harmonic reduction as shown in Figure12, the THD obtained by the new control technique has been drastically reduced.

REFERENCES:

[1] N. Mariun, A. Alam, S. Mahmod, and H. Hizam, “Review of control strategies for power quality conditioners”, in Power and Energy Conference, 2004. PECon 2004. Proceedings. National, 2004, pp. 109– 115.

[2] G. W. Chang and C. M. Yeh, “Optimisation-based strategy for shunt active power filter control under non-ideal supply voltages”, IEE Proceedings - Electric Power Applications, vol. 152, no. 2, p. 182, 2005.

[3] S. George and V. Agarwal, “A DSP Based Optimal Algorithm for Shunt Active Filter Under Nonsinusoidal Supply and Unbalanced Load Conditions”, Power Electronics, IEEE Transactions on, vol. 22, no. 2, pp. 593 –601, Mar. 2007.

[4] M. I. M. Montero, E. R. Cadaval, and F. B. Gonzalez, “Comparison of Control Strategies for Shunt Active Power Filters in Three-Phase Four-Wire Systems”, Power Electronics, IEEE Transactions on, vol. 22, no. 1, pp. 229 –236, Jan. 2007.

[5] M. Abdusalam, P. Poure, and S. Saadate, “Hardware implementation of a three-phase active filter system with harmonic isolation based on self-tuning-filter”, in IEEE Power Electronics Specialists  Conference, 2008. PESC 2008, 2008, pp. 2875–2881.,

Three-Phase Shunt Active Power Filter for Power Improvement Quality using Sliding Mode Controller

ABSTRACT:

In this paper, experimental study of Sliding Mode Controller (SMC) DC bus voltage of three phase shunt active power filter (APF), to improve power quality by compensating harmonics and reactive power required by nonlinear load is proposed. The algorithm used to identify the reference currents is based on the Self Tuning Filter (STF). For generation of the pulse switching of the IGBTs inverter the hysteresis current controller is used, implemented into an analogue card. Finally, various experimental results are presented under steady state and transient conditions.

KEYWORDS:

1.      Shunt Active Power Filter (APF)

2.       Total Harmonic Distortion (THD)

3.       Sliding Mode Controller (SMC)

4.      Self Tuning Filter (STF)

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

\

Fig. 1: The basic compensation principle of the shunt APF.

 EXPECTED SIMULATION RESULTS:

\

Fig. 2. Experimental APF results: load current iL (A), filter current iF (A)

and source current iS (A). Ch1 to Ch4 scale: 5 A/div. Time scale: 20 ms/div.

\

Fig. 3. Experimental APF results: load current iL (A), filter current iF (A),

source current iS (A) and source voltage Vs (V). Ch1 and Ch3 scale: 5 A/div;

Ch2 scale: 100 V/div;Ch4 scale: 80 V/div; Time scale: 10 ms/div.

\

Figure 4. Experimental APF results : load current iL(A), filter current iF(A) ,

source current iS(A) and DC voltage Vdc(V). Ch1,Ch3 and Ch4 scale: 10

A/div. Ch2 scale: 100 V/div. Time scale: 20 ms/div.

\

Figure 5. Experimental APF results: DC voltage Vdc (V) and DC reference

voltage V*dc (V). Ch1 and Ch2 scale: 100 V/div. Time scale: 1s/div

CONCLUSION:

The control of the shunt Active Power Filter was divided in three parts, the first one realized by the dSPACE system to generate the reference currents, the second one achieved by an analogue card for the switching pattern generation, implementing a hysteresis current controller and the third party use a sliding mode controller SMC. A SMC controlled shunt active power filter has been studied to improve the power quality by compensating both harmonics and reactive power requirement of the nonlinear load. The performance of the SMC controller has been developed in real time process and successfully tested in the laboratory The results of experiment study of APF control technique presented in this paper are found quite satisfactory to eliminate harmonics and reactive power components from utility current. The shunt APF presented in this paper for the compensation of harmonic current components in non-linear load was effective for harmonic isolation and keeping the utility supply line current sinusoidal. The validity of this technique was proved on the basis of experiment results. The APF is found effective to meet IEEE- 519-1992 standard recommendations on harmonics levels.

REFERENCES:

[1] Chaoui; J.P.Gaubert; F.Krim; G.Champenois, “PI Controlled Threephase Shunt Active Power Filter for Power Quality Improvement” A. “Electric Power Components and Systems, 1532-5016, Volume 35, Issue 12, 2007, Pages 1331 – 1344.

[2] D. Benatous, R. Abdessemed, “Digital voltage control of AC/DC PWM Converter with improved power factor and supply current ”, Journal of electric machines and power systems, Taylor and francis, 2000.

[3] G. A. Capolino, A. Golea, H. Henao, “Système de réduction des perturbations réseau pour commande vectorielle ”, Proc. Colloque SEE Perturbations Réciproques des Convertisseurs et des Réseaux, Nantes, 6 juillet 1992.

[4] M. Abdusalam, P. Poure and S. Saadate,’’ A New control scheme of hybrid active filter using Self-Tuning Filter,’’ POWERENG, International Conference on Power Engineering , Energy and Electrical Drives, Setubal Portugal,12-14 April (2007).

[5] M. Abdusalam, P. Poure and S. Saadate, « Study and experimental +6validation of harmonic isolation based on Self-Tuning-Filter for threephase active filter ». ISIE, IEEE International Symposium on Industrial Electronics, Cambridge, UK, (2008).

Performance Improvement of Active Power Filters based on P-Q and D-Q Control Methods under Non-Ideal Supply Voltage Conditions

ABSTRACT:

In this paper, we investigate the effect of unbalanced and distorted supply voltages on the performance of active power filters that are based on the well-known p-q and d-q control methods. Our analysis shows that the harmonic suppression performance of the p-q and d-q control methods deteriorates when non-ideal sources are used. We propose the use of a self tuning filter (STF) with the p-q theory or d-q method as a way of alleviating the detrimental effects of non-ideal supply voltages. Simulation results show that the proposed method can improve the performance of active power filters under non-ideal voltage conditions.

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1.Block diagram of simulated APF

EXPECTED SIMULATION RESULTS: 

Fig.2 Three phase balanced and undistorted (ideal) source voltage

Fig.3. Supply currents with p-q method under case 1. (THDi=2.1%)

Fig.4. Supply currents with d-q method under case 1. (THDi=2.07)

Fig.5. Distorted and unbalanced source voltages for case 2.

Fig.6. Supply currents with p-q method under case 2.

Fig.7. Supply currents with d-q method under case 2.

Fig.8. Supply currents with STF based p-q method under case 3.

Fig.9. Supply currents with STF based d-q method under case 3.

CONCLUSION:

In this paper, we consider the effect of an unbalanced and distorted supply on the performance of the well-known p-q theory and d-q methods for active power filters. The ability of these methods to combat current harmonics deteriorates significantly when a non-ideal supply voltage is used. A modification to the p-q and d-q methods is then proposed for alleviating the effects of an imperfect supply. This involves the use of a self-tuning filter (STF) with p-q theory and the d-q method. We show that the total harmonic distortion of source current (THDi) can be reduced by up to around 2.30 % with the use of a STF under non-ideal voltage conditions. In addition, our comparative results show that an STFbased d-q method performs better than an STF-based p-q theory.

REFERENCES:

[1] W. Mack Grady, S. Santoso, "Understanding power system harmonics", IEEE Power Eng. Rev. 21 (November (11)) (2001) 8-11.

[2] S. Biricik, O. C. Ozerdem "Investigation of Switched Capacitors Effect on Harmonic Distortion Levels and Performance Analysis with Active Power Filter", Przeglad Elektrotechniczny, ISSN 0033-2097, R. 86 NR 11a/2010, pp 13-17.

[3] S. Buso, L. Malesani, P. Mattavelli, "Comparison of current control techniques for active filter applications," Industrial Electronics, IEEE Transactions on , vol.45, no.5, pp.722-729, Oct 1998.

[4] H. Akagi, Y. Kanazawa, A. Nabae, "Generalized Theory of the Instantaneous Reactive Power in Three-Phase Circuits", IPEC'83- Int. Power Electronics Conf., Tokyo, Japan, 1983, pp. 1375-1386.

[5] M. Asadi, A. Jalilian, H. F. Farahani, "Compensation of Unbalanced Non Linear Load and neutral currents using stationary Reference Frame in Shunt Active Filters," Harmonics and Quality of Power (ICHQP), 2010 14^th International Conference on, vol., no., pp.1-5, 26-29 Sept. 2010.