Wind Energy Fed UPQC System for Power Quality Improvement

ABSTRACT

The extensive use of non-linear loads in domestic, industrial and commercial services origin harmonic complications. Harmonics make malfunctions in profound equipment, voltage drop across the network, conductor heat increases and overvoltage through resonance. All these problems can be remunerated by using Unified Power Quality Controller (UPQC) and the operation of UPQC depends upon the available voltage across capacitor present in dc link.

If the capacitor voltage is maintained constant then it gives satisfactory performance. The proposed research is basically on designing of Wind energy fed to the dc link capacitor of UPQC so as to maintain proper voltage across it and operate the UPQC for power quality analysis. The proposed technique is the grouping of shunt and series Active Power Filter (APF) to form UPQC

Which is fed wind energy system and connected to grid for better response in the output. In this paper, the simulation model of series APF, shunt APF, UPQC and Wind energy with UPQC are design in Matlab. The proposed Wind energy-UPQC is design in Matlab simulation for reduction of voltage sag, swell, harmonics in load current and compensation of active and reactive power.

KEYWORDS

  1. Harmonics
  2. Power quality
  3. Unified power quality conditioner
  4. Wind energy

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION

The advantage of wind energy system is to retain a constant voltage of 600 volts across the DC-Link capacitor. In this work the wind energy with boost converter output is 600V and simulation of wind energy-UPQC maintains constant voltage of 600V when Sag, Swell and Interruption occur.

It also reduces the harmonics content to 2.33% if any nonlinear load is associated as shown in Figure 19. Hence the proposed scheme can regulate active and reactive power injection to the grid and compensate voltage sag and swell in addition to the other usual operation of UPQC effectible as the voltage across the dc link capacitor is maintained constant. Figure 20 shows DC link voltage.

REFERENCES

[1] Carrasco JM, Franquelo LG, Bialasiewicz JT, Galván E, PortilloGuisado RC, Prats MM, León JI, Moreno-Alfonso N. Power-electronic systems for the grid integration of renewable energy sources: A survey. IEEE Transactions on industrial electronics. 2006; 53(4): 1002-1016.

[2] Samal S, Hota PK. Power Quality Improvement by Solar Photo-voltaic/Wind Energy Integrated System Using Unified Power Quality Conditioner. International Journal of Power Electronics and Drive Systems (IJPEDS). 2017; 8(3): 1424.

[3] Samal S, Hota PK. Power Quality Improvement by Solar Photo-voltaic/Fuel Cell Integrated System Using Unified Power Quality Conditioner. International Journal of Renewable Energy Research (IJRER). 2017; 7(4): 2075-84.

[4] Samal S, Hota PK. Design and analysis of solar PV-fuel cell and wind energy based microgrid system for power quality improvement. Cogent Engineering. 2017; 4(1): 1402453.

[5] Basu M, Das SP, Dubey GK. Comparative evaluation of two models of UPQC for suitable interface to enhance power quality. Electric Power Systems Research. 2007; 77(7): 821-830.

 

Fuzzy Sliding Mode Control for Photovoltaic System

ABSTRACT

In this study, a fuzzy sliding mode control (FSMC) based maximum power point tracking strategy has been applied for photovoltaic (PV) system. The key idea of the proposed technique is to combine the performances of the fuzzy logic and the sliding mode control in order to improve the generated power for a given set of climatic conditions.

Different from traditional sliding mode control, the developed FSMC integrates two parts. The first part uses a fuzzy logic controller with two inputs and 25 rules as an equivalent controller while the second part is designed for an online adjusting of the switching controller’s gain using a fuzzy tuner with one input and one output.

Simulation results showed the effectiveness of the proposed approach achieving maximum power point. The fuzzy sliding mode (FSM) controller takes less time to track the maximum power point, reduced the oscillation around the operating point and also removed the chattering phenomena that could lead to decrease the efficiency of the photovoltaic system.

KEYWORDS

  1. DC-DC converter
  2. Fuzzy sliding mode control
  3. photovoltaic system
  4. MPPT
  5. Solar energy

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION

In this paper, a fuzzy sliding mode controller based MPPT technique was developed and tested. The proposed controller is designed by combining the fuzzy logic and sliding mode control to guarantee the stability and the tracking performance and also to avoid the drawbacks of the traditional SM and FL controllers.

A Matlab/Simulink based simulation of a stand-alone PV system under varying climatic conditions and two levels of load was carried out to validate the proposed controller.

Simulation results demonstrate that the designed FSMC-MPPT exhibits good responses as it successfully and accurately achieved the maximum power point with a significantly higher performance than the P&O, SM and FLC strategies. The proposed approach provides a feasible approach to control PV power systems.

REFERENCES

[1] Dounis, A.I., Kofinas, P., Alafodimos, C., &Tseles, D. (2013). Adaptive fuzzy gain scheduling PID controller for maximum power point tracking of photovoltaic system. Renewable energy, 60, 202-214.

[2] Bhatnagar, P., & Nema, R.K. (2013). Maximum power point tracking control techniques: State-of-the-art in photovoltaic applications. Renewable and Sustainable Energy Reviews, 23, 224-241.

[3] Farhat, M., Barambones, O., & Sbita, L. (2015). Efficiency optimization of a DSP-based standalone PV system using a stable single input fuzzy logic controller. Renewable and Sustainable Energy Reviews, 49, 907-920.

[4] Kalashani, Mostafa Barzegar et Farsadi, Murtaza. New Structure for Photovoltaic Systems with Maximum Power Point Tracking Ability. International Journal of Power Electronics and Drive Systems, 2014, vol. 4, no 4, p. 489.

[5] Liu, F., Kang, Y., Zhang, Y., & Duan, S. (2008, June). Comparison of P&O and hill climbing MPPT methods for grid-connected PV converter. In Industrial Electronics and Applications, 2008. ICIEA 2008. 3rd IEEE Conference on (pp. 804-807). IEEE.

A modified PV-wind-PEMFCS-based hybrid UPQC system with combined DVR/STATCOM operation byharmonic compensation

ABSTRACT

This paper describes an improved Flexible Alternating Current Transmission System (FACTS)-based custom power controller with dynamic voltage restorer (DVR), static compensator (STATCOM) and unified power quality conditioner (UPQC) topology. The proposed controller can feed the power to grid and proficiently moderate the power quality problems like sag, swell, flicker, voltage interruption

Reactive and active power compensation and voltage disturbances with harmonic problems to make sure power quality in the distribution system. The proposed configuration utilizes the Distributed generations (DGs), e.g. Photovoltaic (PV), wind and proton exchange membrane fuel cell stack connected to the micro-grid for realilazisation of DVR, STATCOM and UPQC operation with reduced filtering requirements.

Space vector pulse width modulation -based hybrid cascade bottom leg multilevel inverter has been used for this purpose. The proposed topology has been simulated using MATLAB/Simulink and validated experimentally on a practical system. It is shown that the UPQC performs significantly better than the DVR and STATCOM for the improvement of different power quality issues.

KEYWORDS

  1. Hybrid cascade bottom leg multilevel inverter
  2. Dynamic voltage restorer
  3. Static compensator
  4. Unified power quality conditioner
  5. Space vector pulse width modulation
  6. Proton exchange membrane fuel cell stack
  7. Power quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

This paper investigates the combined renewable sources of PV-wind-PEMFCS-DVR, PV-wind-PEMFCSSTATCOM and PV-wind-PEMFCS-UPQC system for the purpose of simultaneous compensation and active power injection. This proposed method is capable to compensate network power quality issues and mitigate their effects on sensitive loads in distribution power systems.

The simulation and hardware outcomes specify the capability of custom power device in mitigating the voltage variation and harmonic polluting loads. The output voltage harmonics is reduced by SVPWM switching for the operation of DVR, STATCOM or UPQC modes. The proposed system also decreases the overall voltage THD in the micro-grid

decreases the total system loss, improves the dc link voltage, increases the effecting speed, solves the loss of commutation, minimizes the harmonics and optimizes the highfrequency switching problems. The proposed method is simple and can be easily implemented with the help of already available drive compatible hardware.

REFERENCES

[1] Kadri R, Andrer H, Gaubert J-P, et al. Modeling of the photovoltaic cell circuit parameters for optimum connection model and real-time emulator with partial shadow conditions. Energy. 2012 Jun;42(1):57–67. Available from: https://doi.org/10.1016/j.energy.2011. 10.018

[2] Bouilouta A, Mellit A, Kalogirou SA. New MPPT method for stand-alone photovoltaic systems operating under partially shaded conditions. Energy. 2013;55:1172–1185.

[3] Rahim KNA, Ping HW, Selvaraj J. Photovoltaic module modeling using simulink/matlab. Procedia Environ Sci. 2013;17:537–546.

[4] Dali M, Belhadj J, Roboam X. Hybrid solar-wind system with battery storage operating in grid-connected and standalone mode: control and energy managementexperimental investigation. Energy. 2010;35:2587– 2595.

[5] Bollen M. Understanding power quality problems: voltage sag and interruptions. New York: IEEE Press; 1999.

The Fastest MPPT Tracking Algorithm for a PV array fed BLDC Motor Driven Air Conditioning system

ABSTRACT:

The fastest and novel adaptive voltage reference MPPT tracking algorithm for PV cluster sustained BLDC drive for aerating and cooling application is proposed in this paper. The fastest maximum power point tracking (MPPT) algorithm tracks the power instantaneously if there is any change in the solar irradiation.

Low cost and energy efficiency is achieved by removing the conventional DC/DC boost converter stage which reduces the switching losses and further reduces the overall cost of the system thereby minimizing the power conversion stages.

The proposed quickest MPPT algorithm for BLDC motor driven PV array fed air conditioning system is designed and modelled such that the performance is not affected even under the dynamic conditions. The proposed system is validated by simulation studies.

KEYWORDS:

  1. Instantaneous
  2. Low cost
  3. Efficient
  4. MPPT
  5. BLDC
  6. Air conditioner compressor

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this study, a novel adaptive constant voltage reference MPPT technique was proposed to extort maximum power from solar panels and simultaneously uses PV voltage and current deviations to track the Maximum power point of a PV array under varying irradiance conditions has been presented in this paper.

The fastest MPPT algorithm is simulated and discussed to extract maximum power from solar panels without using DC-DC converters thereby reducing switching losses which in turn increasesr efficiency and reduces the cost for PV array fed BLDC Motor driven air conditioning system. The MATLAB simulation results effectively exhibit that, the proposed adaptive constant voltage MPPT algorithm works fine and shows good dynamic and steady state performance.

REFERENCES:

[1] Rodrigo A. Gonzalez, Marcelo A. Perez, Hugues Renaudineau and Freddy Flores-Bahamonde, “Fast Maximum Power Point Tracking Algorithm based on Switching Signals Modification,” IEEE International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), pp. 448-453, 4-6 April 2017.

[2] Hassan Fathabadi, “Novel fast dynamic MPPT (maximum power point tracking) technique with the capability of very high accurate power tracking,”Elsevier journal Energy., Vol. 94, pp. 466-475, Jan. 2016.

[3] E. Mamarelis, G. Petrone and G. Spagnuolo, “Capacitor Peak Current Control for MPPT Photovoltaic Applications,” 39th Annual Conference of the IEEE Industrial Electronics Society, pp. 3347–3352, Nov 2013.

[4] Arash Kalantari , A.Rahmati and A.Abrishamifar, “A Faster Maximum Power Point Tracker Using Peak Current Control,” IEEE Symposium on Industrial Electronics and Applications, pp. 117–122, October 4-6, 2009.

[5] Neil S. D’Souza, Luiz A. C. Lopes, and Xuejun Liu, “Peak Current Control Based Maximum Power Point Trackers For Faster Transient Responses,” Canadian Conference on Electrical and Computer Engineering on 7-10 May 2006.

A Seven Level Modified Cascaded H Bridge Inverter

ABSTRACT:

 This paper presents a new single phase seven level inverter topology is suggested to reduced number of switches for seven level cascaded multilevel inverter. A multilevel inverter is used in power conversion methodology for, high power application and high voltage in today’s power grid, transportation systems, transmission system and industrial motor drives.

This paper focus on modelling and simulation of single-phase inverter as a frequency changer by PWM. The model is implemented using MATLAB/Simulink software. The operation procedure of the inverter is detailed and is demonstrated with Simulink. Hence suggested model provides improved performance or more effective with less switch loss and total harmonic distortion. The simulation is carried out in MATLAB2018b for modified cascaded seven level H bridge inverter also shown its simulation.

KEYWORDS:

  1. Inverter
  2. Multilevel inverter
  3. Cascaded H-bridge
  4. Modified cascaded H-bridge

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, a cascaded H-bridge ML topology was simulated and it is concluded that for producing the same 7- level output voltage, the proposed ML inverter requires only 6 switches whereas the conventional type requires 8 switches. This difference will be larger if the number of output voltage level is further increased.

Therefore, the proposed cascaded H-bridge ML topology can eliminate roughly half the number of switches, their gate drivers compared with the existing cascaded MLI counterparts. Despite a higher total VA rating of the switches, the cascaded ML inverters are cost less due to the savings from the eliminated gate drivers. The proposed concept is validated through simulation studies.

REFERENCES:                                                           

[1]. B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques: John Wiley & Sons, 2014.

[2]. I. Gowaid, G. Adam, A. Massoud, S. Ahmed, and B. Williams, “Hybrid and Modular Multilevel Converter Designs for Isolated HVDC-DC Converters,” IEEE Journal Emerg. and Select. Topics in Power Electron., vol. PP, no. 99, p. 1, 2017.

[3]. H. Vahedi, K. Al-Haddad, Y. Ounejjar, and K. Addoweesh, “Crossover Switches Cell (CSC): A New Multilevel Inverter Topology with Maximum Voltage Levels and Minimum DC Sources,” in IECON 2013-39th Annual Conference on IEEE Industrial Electronics Society, Austria, 2013, pp. 54-59.

[4]. P. W. Hammond, “A new approach to enhance power quality for medium voltage drives,” in Petroleum and Chemical Industry Conference, 1995. Record of Conference Papers., Industry Applications Society 42nd Annual, 1995, pp. 231-235.

[5]. A. Nabae, I. Takahashi, and H. Akagi, “A new neutral-point-clamped PWM inverter,” IEEE Trans. Ind. Applications, no. 5, pp. 518-523, 1981.

Finite Control Set Model Predictive Control for Grid Connected Packed U Cells Multilevel Inverter

ABSTRACT:

 This paper presents a Finite Control Set Model Predictive Control (FCS-MPC) for grid-tied Packed U Cells (PUC) Multilevel Inverter (MLI). The system under study consists of a single-phase 3-cells PUC inverter connected to the grid through filtering inductor. The proposed competitive topology allows the generation of 7-level output voltage with reduction of passive and active components compared to the conventional multilevel inverters.

The aim of the proposed FCS-MPC technique is to achieve, under various operating conditions, grid-tie current injection with unity power factor and low Total Harmonic Distortion (THD) while balancing the capacitor voltage. Parameters sensitivity analysis was also conducted. The study is conducted on a low power case study single-phase 3-cells PUC inverter and with possible extension to higher number of cells. Theoretical analysis, simulation, and experimental results are presented and compared.

KEYWORDS:

  1. Grid Connection
  2. Model Predictive Control
  3. Packed U Cells Inverter
  4. PUC

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

This paper presented the design, simulations, and experimental validation of a FCS-MPC technique that properly deals with the complex nature of the PUC. Digital simulation for a grid-connected 7-level single-phase PUC inverter was carried out. The simulation results showed that the proposed MPC is capable of simultaneously controlling multi variables of the PUC inverter.

The tuning of the weighting factor was conducted successfully based on minimizing the grid current THD as well as the capacitor voltage error. Using the properly selected weighting factor, the MPC has shown an efficient and stable tracking of the reference current at steady state and fast transient response. It is also capable of maintaining the capacitor voltage at its pre-selected and desired level.

Parameters sensitivity analysis was carried out and showed that the parameters variation does not have a significant effect on the controller performance. The obtained experimental results confirmed the simulation results and demonstrated that the proposed MPC is effective in controlling the grid current with high steady-state and dynamic tracking performances while keeping balanced capacitor voltage.

REFERENCES:                                                           

[1] H. Abu-Rub, M. Malinowski, K. Al-Haddad, “Power Electronics for Renewable Energy Systems, Transportation and Industrial Applications”, John Wiley & Sons, 2014.

[2] E. Babaei, S. Alilu and S. Laali, “A New General Topology for Cascaded Multilevel Inverters With Reduced Number of Components Based on Developed H-Bridge,” in IEEE Trans. Ind. Electron., vol. 61, no. 8, pp. 3932-3939, Aug. 2014.

[3] J. Rodríguez, J.S. Lai, F.Z. Peng, “Multilevel Inverters: A Survey of Topologies, Controls, and Applications”, IEEE Trans. Ind. Electron., vol. 49, no. 4, August 2002.

[4] H. Abu-Rub, J. Holtz, J. Rodriguez and G. Baoming, “Medium-Voltage Multilevel Converters—State of the Art, Challenges, and Requirements in Industrial Applications,” IEEE Trans. Ind. Electron., vol.57, no.8, pp.2581-2596, 2010.

[5] J. Chavarria, D. Biel, F. Guinjoan, C. Meza and J. J. Negroni, “Energy-Balance Control of PV Cascaded Multilevel Grid-Connected Inverters Under Level-Shifted and Phase-Shifted PWMs,” IEEE Trans. Ind. Electron., vol.60, no.1, pp.98-111, Jan. 2013.

Design and Simulation of Single-Phase Five-Level Symmetrical Cascaded H-Bridge Multilevel Inverter with Reduces Number of Switches

 ABSTRACT:

Multilevel inverter is an effective and practical solution for increasing power demand and reducing harmonics of ac waveforms. Such inverters synthesize a desired output voltage from several levels of voltages as inputs. This paper analyzes the performance of five level cascaded H-bridge multilevel inverter with reduce number of power switches.

Further by reducing switches and increasing level will reduce filter cost & harmonic content. 5- Level cascaded H-bridge asymmetrical multilevel inverter topology requires 8 switches but in this new multilevel inverter it requires 6 switches in which same multilevel is obtained. Invariably switching losses and cost also reduced. In this .paper only multilevel inverter circuitry will be studied. The performance has been analyzed by the MATLAB/Simulink.

KEYWORDS:

  1. Cascaded multilevel inverter
  2. SPWM
  3. APOD
  4. PD
  5. POD
  6. THD

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

This paper showed that this modified multilevel inverter topology with reduced number of switches can be implemented for industrial drive applications. This multilevel inverter structure and its basic operations have been analyzed. A detailed procedure for calculating required voltage level on each stage has been analyzed.

As conventional five-level inverter involves eight switches, it increases switching losses; cost and circuit complexity. This 5-level inverter engages only six switches which reduces switching losses, cost and circuit complexity. Moreover it effectively reduces lower order harmonics. Therefore effective reduction of total harmonics distortion is achieved.

REFERENCES:

  1. http://www.esru.strath.ac.uk
  2. Kavita M, Arunkumar A, Gokulnath N, Arun S (2012) New cascaded H-bridge multilevel inverter topology with reduced number of switches and sources. IOSR-JEEE 2: 26-36.
  3. Peng FZ, Lai JS (2003) Multilevel converters, A new breed of power Electronics converters. IEEE Trans Ind Appl 32: 509 -517.
  4. Rodriguez J, Lai JS, Peng FZ (2003) Multilevel Inverter: A survey topology control and application. IEEE Trans Ind Electro 49: 724-738.
  5. Nabae A, Takahashi I, Akagi H (2003) New neutral point clamped pwm inverter. IEEE Trans Ind Appl IA-17: 518-523

Reduced DC Link Voltage Active Power Filter Using Modified PUC5 Converter

ABSTRACT:

 In this paper the 5-level Packed U-Cell (PUC5) inverter is reconfigured with two identical DC links operating as an active power filter (APF). Generally, the peak voltage of an APF should be greater than the AC voltage at the point of common coupling (PCC) to ensure boost operation of the converter in order to inject harmonic current into the system effectively; therefore, full compensation can be obtained.

The proposed modified PUC5 (MPUC5) converter has two equally regulated separated DC links, which can operate at no load condition useful for APF application. Those divided DC terminals amplitudes are added at the input of the MPUC5 converter to generate a boosted voltage that is higher than the PCC voltage.

Consequently, the reduced DC links voltages are achieved since they do not individually need to be higher than the PCC voltage due to the mentioned fact that their summation has to be higher than PCC voltage. The voltage balancing unit is integrated into modulation technique to be decoupled from the APF controller. The proposed APF is practically tested to validate its good dynamic performance in harmonic elimination, AC side power factor correction, reactive power compensation and power quality improvement.

KEYWORDS:

  1. Active Power Filter
  2. PUC5
  3. Harmonic Elimination
  4. Power Factor Correction
  5. Power Quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The MPUC5 configuration has been introduced as a modification to the PUC5 topology with the advantage of DC voltage boosting. It has been employed as an APF with reduced DC link voltages. The voltage balancing between DC capacitors in the APF has been done by the redundant switching states. Since the two capacitors voltages are regulated without external controllers

A simple cascaded control technique has been implemented to keep the sum of two DC voltages values at the reference level as well as synchronizing the source current with grid voltage. Finally, the performance of the MPUC5 APF has been tested practically. Results have shown that the proposed configuration operated well in current harmonic elimination, reactive power compensation and power factor correction.

REFERENCES:

[1] B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques: John Wiley & Sons, 2014.

[2] S. Rahmani, K. Al-Haddad, H. Y. Kanaan, and B. Singh, “Implementation and simulation of modified PWM with two current control techniques applied to single-phase shunt hybrid power filter,” IEE Proc. Electric Power Applications, vol. 153, no. 3, pp. 317-326, 2006.

[3] H. Zhang, S. J. Finney, A. Massoud, and B. W. Williams, “An SVM algorithm to balance the capacitor voltages of the three-level NPC active power filter,” IEEE Trans. Power Electron., vol. 23, no. 6, pp. 2694-2702, 2008.

[4] S. Du, J. Liu, and J. Lin, “Hybrid cascaded H-bridge converter for harmonic current compensation,” IEEE Trans. Power Electron., vol. 28, no. 5, pp. 2170-2179, 2013.

[5] M. Sharifzadeh, H. Vahedi, R. Portillo, M. Khenar, A. Sheikholeslami, L. G. Franquelo, et al., “Hybrid SHM-SHE Pulse Amplitude Modulation for High Power Four-Leg Inverter,” IEEE Trans. Ind. Electron., vol. 63, no. 11, pp. 7234-7242, 2016.

Real-Time Implementation of Model Predictive Control on 7-Level Packed U-Cell Inverter

ABSTRACT:

In this paper a model predictive control (MPC) has been designed and implemented on the Packed U-Cell (PUC) inverter which has one isolated DC source and one capacitor as an auxiliary DC link. The MPC is designed to regulate the capacitor voltage at the desired magnitude to have seven voltage levels at the output of the inverter. Since grid-connected application is targeted by this application, the inverter should be capable of supplying requested amount of active and reactive power at the point of common coupling (PCC) as well. Therefore, MPC should also consider the line current control in order to monitor the exchange of reactive power with the grid while injecting appropriate active power at low THD. Various experimental tests including change in DC source voltage, active power variation and operation at different power factor (PF) have been performed on a laboratory prototype to validate the good performance obtained by the proposed MPC. The dynamic performance of the controller during sudden changes in dc capacitor voltage, supply current and PF demonstrates the fast and accurate response and the superior operation of the proposed controller.

KEYWORDS:

  1. PUC Inverter
  2. Multilevel Inverter
  3. Model Predictive Control
  4. Grid-Connected PV
  5. Power Quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a Model Predictive Control has been designed for the 7-level PUC inverter in grid-connected mode of operation, an excellent candidate for photovoltaic and utility interface application to deliver green power to the utility. MPC is a simple and intuitive method that does not have confusing gains to adjust as well as featuring fast response during any change in the system parameters. Experimental results have been provided to show the fast response of the implemented controller on the grid-connected multilevel PUC inverter. It has been demonstrated that the DC link capacitor voltage has been regulated at desired level and 7-level voltage waveform has been generated at the output of the inverter. The injected current to the grid was successfully controlled to have regulated amplitude and synchronized waveform with the grid voltage to deliver maximum power with unity power factor. Moreover, the PF has been controlled easily to exchange reactive power with the grid while injecting the available active power. Exhaustive experimental results including change in the grid current reference, DC source and AC grid voltages variations, as well as PF have been tested and results have been illustrated which ensured the good dynamic performance of the proposed controller applied on the gridconnected PUC inverter.

REFERENCES:

[1] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[2] H. Mortazavi, H. Mehrjerdi, M. Saad, S. Lefebvre, D. Asber, and L. Lenoir, “A Monitoring Technique for Reversed Power Flow Detection With High PV Penetration Level,” IEEE Trans. Smart Grid, vol. 6, no. 5, pp. 2221-2232, 2015.

[3] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galván, R. P. Guisado, M. A. Prats, J. I. León, and N. Moreno-Alfonso, “Powerelectronic systems for the grid integration of renewable energy sources: A survey,” IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002-1016, 2006.

[4] M. G. Kashani, M. Mobarrez, and S. Bhattacharya, “Variable interleaving technique for photovoltaic cascaded DC-DC converters,” in IECON 2014-40th Annual Conference of the IEE EIndustrial Electronics Society, 2014, pp. 5612-5617.

[5] M. Mobarrez, M. G. Kashani, G. Chavan, and S. Bhattacharya, “A Novel Control Approach for Protection of Multi-Terminal VSC based HVDC Transmission System against DC Faults,” in ECCE 2015- Energy Conversion Congress & Exposition, Canada, 2015, pp. 4208- 4213.

Real-Time Implementation of a Packed U-Cell Seven-Level Inverter with Low Switching Frequency Voltage Regulator

ABSTRACT:

 In this paper a new cascaded nonlinear controller has been designed and implemented on the packed U-Cell (PUC) seven-level inverter. Proposed controller has been designed based on a simplified model of PUC inverter and consists of a voltage controller as outer loop and a current controller as inner loop. The outer loop regulates the PUC inverter capacitor voltage as the second DC bus. The inner loop is in charge of controlling the flowing current which is also used to charge and discharge that capacitor.

The main goal of the whole system is to keep the DC capacitor voltage at a certain level results in generating a smooth and quasi-sine-wave 7-level voltage waveform at the output of the inverter with low switching frequency. The proposed controller performance is verified through experimental tests.

Practical results prove the good dynamic performance of the controller in fixing the PUC capacitor voltage for various and variable load conditions and yet generating low harmonic 7-level voltage waveform to deliver power to the loads. Operation as an uninterruptible power supply (UPS) or AC loads interface for photovoltaic energy conversion applications is targeted.

KEYWORDS:

  1. Packed U-Cell
  2. Multilevel Inverter
  3. Voltage Balancing
  4. Nonlinear Controller
  5. Renewable energy conversion

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper a new cascaded nonlinear controller has been designed for 7-level PUC inverter based on the simple model derived by multilevel inverter topology concept. Experimental results showed appropriate dynamic performance of the proposed controller in stand-alone mode as UPS, renewable energy conversion system or motor drive applications.

Different changes in the load and DC bus voltage have been made intentionally during the tests to challenge the controller reaction in tracking the voltage and current references. Proposed controller demonstrated satisfying performance in fixing the capacitor voltage of the PUC inverter, generating seven-level voltage with low harmonic content at the output of the PUC inverter and ensures low switching frequency operation of those switches.

By applying the designed controller on the 7-level PUC inverter it can be promised to have a multilevel converter with maximum voltage levels while using less active switches and DC sources aims at manufacturing a low-cost converter with high efficiency, low switching frequency, low power losses and also low harmonic contents without using any additional bulky filters.

REFERENCES:

[1] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[2] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galván, R. P.Guisado, M. A. Prats, et al., “Power-electronic systems for the grid integration of renewable energy sources: A survey,” IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002-1016, 2006.

[3] M. Mobarrez, M. G. Kashani, G. Chavan, and S. Bhattacharya, “A Novel Control Approach for Protection of Multi-Terminal VSC based HVDC Transmission System against DC Faults,” in ECCE 2015- Energy Conversion Congress & Exposition, Canada, 2015, pp. 4208- 4213.

[4] B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques: John Wiley & Sons, 2014.

[5] B. Singh, K. Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron., vol. 46, no. 5, pp. 960-971, 1999.