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.

PUC Converter Review:Topology, Control and Applications

 ABSTRACT:

Packed U-Cell (PUC) converter has been introduced as a 7-level converter in early 2008. Since then, different analysis and projects have been performed on, including various applications such as inverter and rectifier, linear and nonlinear voltage controllers. In this paper, authors try to do a detail review on this topology covering all aspects like topology design in single and three-phase, operation concepts, switching sequences for different multilevel voltage waveform generation, modelling and etc. It is shown that this topology can be comparable to popular multilevel converters (CHB and NPC) in terms of device counts and applications. Moreover, some performed and published works about the PUC are mentioned to show its different industrial applications and some other converter topologies derived based on the PUC. Experimental results are provided to show the good performance of PUC converter in several applications.

KEYWORDS:

1.      Packed U-Cell

2.      Multilevel converter

3.      Active power filter

4.      Active rectifier

5.      Inverter

6.      Power quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

PUC converter generates various voltage levels based on the voltage ratio of its two DC links similar to the CHB topology, while using fewer components. It is an interesting topology in inverter mode due to using only one isolated DC source. It is also attractive in rectifier application because of generating dual output DC terminal in boost and buck mode. As shown in  this paper, the PUC converter can be a good candidate for all modes of operation like standalone/grid-connected inverter and rectifier in various applications including PV systems, active filters, wind turbine, electric transportation, battery chargers, MMC, etc.

REFERENCES:

1] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, et al., "Recent advances and industrial applications of multilevel converters," IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553-2580, 2010.

[2] 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.

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

[4] J. Rodriguez, S. Bernet, P. K. Steimer, and I. E. Lizama, "A survey on neutral point-clamped inverters," IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2219- 2230, 2010.

A Modified Seven Level Cascaded H Bridge Inverter

 ABSTRACT:

 Presently Multilevel inverters are extensively used for high-voltage applications and their execution is exceptionally better to that of regular two-level inverters due to minimized harmonic distortion, lower electromagnetic interference and larger DC link voltages. Nevertheless certain shortcomings are faced such as adding in number of components and voltage balancing problem. In order to overcome these, a seven-level hybrid inverter has been proposed. This topology requires a lesser number of power switches which results in the decrease of multifaceted nature, add up to cost and weight of the inverter. Finally this can be able to generate near sinusoidal voltages and approximately fundamental frequency switching. The simulation and the experimental results of a modified cascaded seven level H bridge inverter with and without LC filter are presented for validation.

KEYWORDS:

1.      Cascaded H-bridge inverter (CHBI)

2.      Seven level hybrid inverter

3.      Asymmetrical DC sources

4.      Total harmonic distortion (THD)

5.      Pulse Width modulation (PWM)

6.      Multi-level Inverter (MLI)

7.      Real time Interface (RTI)

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

A modified cascaded seven level H-bridge inverter was fabricated which has the benefit of reduced THD, portability, and cost has compared to normal cascaded H-bridge inverter. Since the topology requires minimum switches, and low-cost real time interfacing device (Arduino) compared DSP, DSPACE, FPGA, etc., the overall expenditure for fabrication reduces. This paper envisages the working of proposed structure. An LC filter is introduced which helps in getting nearer to sinusoidal waveform. The concepts which are projected are verified through simulation and experimental results.

REFERENCES:

[1] E. Babaei and S.Hosseini, “Charge balance control methods for asymmetrical cascade multilevel converters”. In Proc. ICEMS, Seoul, Korea, 2007, pp, 74-79.

[2] K. Wang, Y. Li, Z. Zheng, and L. Xu, “Voltage balancing and

fluctuation suppression methods of floating capacitors in a new modular multilevel converter,” IEEE Trans. Ind. Electron., vol. 60, no. 5, pp. 1943–1954,May 2013

[3] J. Napoles, A. J. Watson, and J. J. Padilla, “Selective harmonic mitigation technique for cascaded H-bridge converter with nonequal dc link voltages,” IEEE Trans. Ind. Electron., vol. 60, no. 5, pp. 1963–1971, May 2013.

[4] N. Farokhnia, S. H. Fathi, N. Yousefpoor, and M. K. Bakhshizadeh, “Minimisation of total harmonic distortion in a cascaded multilevel inverter by regulating of voltages dc sources,” IET Power Electron., vol. 5, no. 1, pp. 106–114, Jan. 2012.

[5] S. Mekhilef, M. N. Abdul Kadir, and Z. Salam, “Digital control of three phase three-stage hybrid multilevel inverter,” IEEE Trans. Ind. Informat., vol. 9, no. 2, pp. 719–727, May 2013.

 

Performance Analysis of Grid Connected PV/Wind Hybrid Power System during Variations of Environmental Conditions and Load

 ABSTRACT:

This paper investigates a dynamic modeling, simulation and control of Photovoltaic (PV)-wind hybrid system connected to electrical grid and feeds large plant with critical variable loads. The technique of extracting maximum power point is applied for the hybrid power system to capture maximum power under varying climatic conditions. Moreover, Control strategy for power flow is proposed to supply critical load demand of plant. Modeling and simulation of the proposed hybrid system is performed using matlab-Simulink software. The Dynamic performance of the proposed hybrid system is analyzed under different environmental conditions. The simulation results have proven the effectiveness of the proposed maximum power point tracking (MPPT) strategies in response to rapid variations of weather conditions during the day. Moreover, the results show that when the injected power from hybrid system is larger than critical load power, the excess power will be injected to electrical grid. Otherwise, when injected power is lower than critical power demand, electrical utility grid in cooperated with hybrid power system will supply the critical load power. Moreover, when the injected power from hybrid system is unavailable, load demand is entirely fed by electrical utility.

KEYWORDS:

1.      PV

2.      Wind

3.      Hybrid system

4.      MPPT control

5.      DFIG

6.      Load

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, modeling, simulation and control of grid connected photovoltaic-wind hybrid power system have been successfully investigated. The proposed hybrid system consists of two Photovoltaic (PV) stations placed at different locations and one wind farm are integrated into main AC bus and supply large plant with critical variable loads. The incremental conductance MPPT technique is applied for both PV stations to extract maximum power under variations of solar irradiance. Also, an improved MPPT control strategy based on measurement of mechanical power is applied for wind farm to capture the maximum power under changes of wind speed. Moreover, control strategy for power flow is proposed to supply critical load demand of plant. The Dynamic performance of the proposed hybrid system is tested under different environmental conditions such as changes of solar irradiance and wind speed. In addition, the validation of the proposed power flow is evaluated under variation of the critical load demand. The simulation results have proven the robustness of the MPPT control strategies in response to rapid variations in weather conditions during the day. Moreover, the power flow control strategy successfully meets the critical load demand of the plant.

REFERENCES:

[1] R. Benadli and A. Sellami, "Sliding mode control of a photovoltaic-wind hybrid system," in Electrical Sciences and Technologies in Maghreb (CISTEM), 2014 International Conference on, 2014, pp. 1-8.

[2] J. Hossain, N. Sakib, E. Hossain, and R. Bayindir, "Modelling and Simulation of Solar Plant and Storage System: A Step to Microgrid Technology," International Journal of Renewable Energy Research (IJRER), vol. 7, pp. 723-737, 2017.

[3] U. Choi, K. Lee, and F. Blaabjerg, "Power electronics for renewable energy systems: Wind turbine and photovoltaic systems," in Renewable Energy Research and Applications (ICRERA), 2012 International Conference on, 2012, pp. 1-8.

[4] A. B. Oskouei, M. R. Banaei, and M. Sabahi, "Hybrid PV/wind system with quinary asymmetric inverter without increasing DC-link number," Ain Shams Engineering Journal, vol. 7, pp. 579-592, 2016.

[5] H. Laabidi and A. Mami, "Grid connected Wind- Photovoltaic hybrid system," in Energy (IYCE), 2015 5th International Youth Conference on, 2015, pp. 1-8

Integration of Supercapacitor in Photovoltaic Energy Storage: Modelling and Control

 ABSTRACT

Due to the variable characteristics of photovoltaic energy production or the variation of the load, batteries used in storage systems renewable power can undergo many irregular cycles of charge 1 discharge. In turn, this can also have a detrimental effect on the life of the battery and can increase project costs. This paper presents an embedded energy share method between the energy storage system (battery) and the auxiliary energy storage system such as supercapacitors (SC). Supercapacitors are used to improve batteries life and reduce their stresses by providing or absorbing peaks currents as demanded by the load. The photovoltaic cells are connected to DC bus with boost converter and controlled with MPPT  algorithm, Supercapacitors and batteries are linked to the DC bus through the buck-boost converter. The inductive load is connected to the DC bus by a DC-AC converter. The static converters associated with batteries and supercapacitors are controlled by current. The components of the systems are supervised through a block of energy management. The complete model of the system is implemented in MATLAB/Simulink environment. Simulation results are given to show the performance of the proposed control strategy, for the overall system.

KEYWORDS

1.      Photovoltaic

2.      batteries

3.      supercapacitors

4.      DC bus

5.      Energy storage

6.      Energy management

7.      Converters control

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

In this paper, the storage photovoltaic energy by using a combination of Battery-Supercapacitor has been presented. First, the modeling of different components of the system has been addressed. A comparison of different model of SCs is given. Second, a strategy of control and regulation of the DC bus voltage was proposed, to deal with the variation of solar irradiation and/or the variation of the load. This controller gives the better an efficient energy management and ensures continuity of supply by using the methodology that involves a reversible chopper between the batteries and the DC bus and another between the SC and the DC bus to ensure stable voltage on the DC bus of 400V. The three operating scenarios show that the proposed control and management strategies of DC bus are effective and able to supply desired power. It is also shown that SCs can absorb rapid changes in current to reduce the stress on batteries.

REFERENCES

[1] L. Peiwen, "Energy storage is the core of renewable technologies," Nanotechnol. Mag., vol. 2, no. 4, pp. 13-18, Dec. 2008.

[2] Q. Liyan and Q. Wei, "Constant power control of DFTG wind turbines with supercapacitor energy storage," iEEE Trans. Ind. Appl., vol. 47, no. I, pp. 359-367, Jan. 2011.

[3] M. Uzunoglu and M. S. Alam, "Dynamic modeling, design, and simulation of a combined PE M fuel cell and ultracapacitor system for stand-alone residential applications," IEEE Trans. Energy Convers., vol. 21,no. 3,pp. 767-775,Sep. 2006.

[4] B. P. Roberts and C. Sandberg,'The role of energy storage in development of smart grids," Proc. IEEE, vol. 99, no. 6, pp. 1139-1144, June. 2011.

[5] A Khaligh and L. Zhihao, "Battery, ultracapacitor, fuel cell, and hybrid energy storage systems for electric, hybrid electric, fuel cell, and plugin hybrid electric vehicles: State-of-the -art," IEEE Trans. Veh. Technol, vol. 59, no. 6, pp. 2806-2814, Jully. 2010.

Management and Control of Storage Photovoltaic Energy Using Battery-Supercapacitor Combination

 ABSTRACT

Due to the variable characteristics of photovoltaic energy production, batteries used in storage systems renewable power can undergo many irregular cycles of charge I discharge. In turn, this can also have a detrimental effect on the life of the battery and can increase project costs. This paper presents a study of the storage of photovoltaic energy by using a hybrid batteries-Supercapacitors system. Supercapacitors are used to improve batteries life and reduce their stresses. The photovoltaic cells are connected to DC bus (400V) with boost converter and controlled with MPPT algorithm, Supercapacitors and batteries are linked to the DC bus through the buck-boost converter. The inductive load is connected to the DC bus by a DC-AC converter. The static converters associated with batteries and supercapacitors are controlled by current. The components of the systems are supervised through a block of energy management. The complete model of the system is implemented in MATLAB/Simulink environment. Some simulation results prove the effectiveness of the proposed control strategy.

KEYWORDS

1.      Photovoltaic, batteries

2.      Supercapacitors

3.      DC bus

4.      Energy storage

5.      Energy management

6.      Converters control

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION

This paper presents the storage photovoltaic energy by using a combination of Battery-Supercapacitor. Batteries provide energy storage for a relatively long duration, while SCs can absorb rapid changes in current to reduce the stress on batteries. The proposed strategy concerned the regulation of the DC bus voltage for different sources: Photovoltaic, battery and Supercapacitor, despite the variation of solar irradiation. This enabled an efficient energy management and ensures continuity of supply. Simulation results show that the  proposed control and mangement strategies of DC bus are effective and able to supply desired power .

REFERENCES

[I] L. Peiwen, "Energy storage is the core of renewable technologies, " Nanotechnol. Mag., vol. 2, no. 4, pp. 13-18, Dec. 2008.

[2] Q. Liyan and Q. Wei, "Constant power control of DFiG wind turbines with supercapacitor energy storage, " iEEE Trans. Ind. Appl., vol. 47, no. I, pp. 359-367, Jan. 2011.

[3] M. Uzunoglu and M. S. A1am, "Dynamic modeling, design, andsimulation of a combinedPEM fuel cell and ultracapacitor system for stand-alone residential applications, " iEEE Trans. Energy Convers., vol. 21, no. 3, pp. 767-775, Sep. 2006.

[4] B. P. Roberts and C. Sandberg, 'The role of energy storage in development of smart grids, " Proc. iEEE, vol. 99, no. 6, pp. 1139-1144, June. 2011.

[5] A. Khaligh and L. Zhihao, "Battery, ultracapacitor, fuel cell, and hybrid energy storage systems for electric, hybrid electric, fuel cell, and plugin hybrid electric vehicles: State-of-the -art, " iEEE Trans. Veh. Technol, vol. 59, no. 6, pp. 2806-2814, Jully. 2010.

Integration of PV, Battery and Supercapacitor inIslanded Microgrid

ABSTRACT

Nowadays battery is used to stabilize the DC bus voltage but battery has low power density and high energy density. Whereas the supercapacitor has high power density but low energy density. So, for high energy and power density the integration of battery and supercapacitor is more efficient. It is more challenging to integrate the different sources. So it is required a control strategy to integrate the battery and supercapacitor and provide continuous power to the load. It has also shown that the battery and supercapacitor charged in access mode of power and discharged in deficit mode of power. In this paper proposed a new approach to control the power and dc bus voltage.

KEYWORDS

1.      Battery

2.      MPPT Controller

3.      Photo Voltaic Cell

4.      Supercapacitor

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

In this paper proposed controller is used for proper sharing of power between different energy sources. Here LPF is used to differentiate between the average power supplied by battery and transient power supplied by supercapacitor. Now, new scheme of converter is able to deal with fluctuation of voltage. The constant power and constant voltage across load were observed.

 REFERENCES

[1] U. Manandhar et al., “Energy management and control for grid connected hybrid energy storage system under different operating modes,” IEEE Trans. Smart Grid, vol. 10, no. 2, pp. 1626–1636, 2019.

[2] B. H. Nguyen, R. German, J. P. F. Trovao, and A. Bouscayrol, “Real-time energy management of battery/supercapacitor electric vehicles based on an adaptation of pontryagin’s minimum principle,” IEEE Trans. Veh. Technol., vol. 68, no. 1, pp. 203–212, 2019.

[3] Z. Cabrane, M. Ouassaid, and M. Maaroufi, “Battery and supercapacitor for photovoltaic energy storage: A fuzzy logic management,” IET Renew. Power Gener., vol. 11, no. 8, pp. 1157– 1165, 2017.

[4] H. R. Pota, M. J. Hossain, M. A. Mahmud, and R. Gadh, “Control for microgrids with inverter connected renewable energy resources,” IEEE Power Energy Soc. Gen. Meet., vol. 2014-October, no. October, pp. 27–31, 2014.

[5] S. Angalaeswari, O. V. G. Swathika, V. Ananthakrishnan, J. L. F. Daya, and K. Jamuna, “Efficient Power Management of Grid operated MicroGrid Using Fuzzy Logic Controller (FLC),” Energy Procedia, vol. 117, pp. 268–274, 2017.