Characteristics Behavior of Shunt DC Electric Spring For Mitigating DC Microgrid Issues

 ABSTRACT:

There is a huge pervasive consideration of integrating renewable energy sources (RES) to DC power system. Most of the modern loads are DC. Photovoltaic (PV) integrated DC microgrids feature remarkable advantages such as providing DC which can be directly utilized in DC grids that eliminates major step of ACDC conversion. However, intermittency of RES and presence of some non- idealistic like voltage fluctuation, droop effect, faults and harmonics causes instability problems in DC microgrid. This leads to voltage weakening, potential blackout and damage to equipment. To deal with inconsistency and improbability of RES new emerging demand side management (DSM) technology has been developed called Electric Spring (ES). ES can be employed in AC or DC grid for supply-demand management. DC Electric Spring (DC-ES) is a unique method of distributed voltage control over traditional single point control by effectively handling supply. This paper comprises one of the types of DC-ES called the shunt DC-ES for voltage regulation and Fault Ride Through (FRT) support with various mode of operation on DC bus. To demonstrate the performance analysis and to alleviate DC microgrid issues, DC-ES is implemented on 48V DC system. Moreover, the detail comprehensive characteristics behavior of shunt DC-ES is presented and validated using MATLAB software.

KEYWORDS:

1.      DC-Electric Spring

2.      DC Microgrid

3.      Fault Ride Through

4.      Renewable energy sources

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 This paper presents an effective proficiency of shunt DC-ES to fix the CL voltage and to improve Fault Ride Through (FRT) capability of DC system in case of low power DPGS like PV. The comprehensive investigation highlights the characteristics performance of shunt DC-ES for voltage variations during various DC system contingencies without energy consumption. The presented results verifies the successful performance of shunt DC-ES for mitigating different issues in DC microgrids such as voltage regulation and FRT support. It is found that the shunt configuration of DC-ES exactly follows its ideal characteristics with an excellent dynamic response.

REFERENCES:

[1] X. Chen, M. Shi, H. Sun, and H. He “Distributed Cooperative Control and Stability Analysis of Multiple DC Electric Springs in a DC Microgrid,” IEEE Trans. Ind. Electron, vol. 65, no. 7, pp. 5611-5622, July 2018.

[2] N. Hatziargyriou, Microgrids Architecture and Control, 1st ed. Wiley, 2014.

[3] S. Anand, B. G. Fernandes, and M. Guerrero, “Distributed control to ensure proportional load sharing and improve voltage regulation in low voltage DC microgrids,” IEEE Trans. Power Electron., vol. 28, no. 4, pp. 1900–1913, Apr. 2013.

[4] K. T. Mok, M. H. Wang, S. C. Tan, and S.Y.R. Hui, ‘‘DC electric springs -- An emerging technology for DC grids,’’ IEEE Applied Power Electronics and Exposition (APEC), Mar. 2015.

[5] Y. Yang, S. C. Tan, and S.Y.R. Hui, “Enhanced Digital PI Control with state Variable Feedback Loop for DC Electric Springs”, in Proc. IEEE Applied Power Electronics Confernce and Exposition (APEC), March 2017.

Design and simulation of cascaded H-bridge 5-level inverter for grid connection system based on multi-carrier PWM technique

 ABSTRACT:

Cascaded H-Bridge (CHB) multi-level inverter has become attractive in medium voltage and grid connection to improve power quality with high efficiency, and low switching losses. Voltage Oriented Control (VOC) regulates the injected power and the connection between the cascaded H-bridge inverter and the utility grid. In the modulation stage for the VOC, there are several techniques such as Space Vector Pulse Width Modulation (SVPWM), Multi-Carrier Pulse Width Modulation (MCPWM), Selective Harmonic Elimination (SHE) used to obtain gating pulses for the IGBTs switches. In this paper, a three-phase 5-level CHB inverter with a grid connection system is present and the technique of MCPWM is used. A comparative study between each method of (MCPWM) using MATLAB/ Simulink environment has been done on the Total Harmonic Distortion (THD) for inverter phase voltage and current with different injected reference current values. It is found that phase current THD is less with the Phase Shift PWM (PS-PWM) technique.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 This paper involves a study and analysis for a three-phase 5-level cascaded H-bridge inverter for grid connection with unity power factor. The system controlled by traditional voltage-oriented control. Carrier shift techniques are used in modulation stag and simulated by MATLAB/Simulink environment. The application of Fast Fourier Transform (FFT) analysis for THD in these techniques shows that the total harmonic distortion for the inverter current by using Phase Shift Pulse Width Modulation (PS-PWM) is small compared with other existing methods. It means that high-quality output current and even high-power distribution are obtained; therefore, this technique is suitable for grid connection.

REFERENCES:

[1] Hasan N S, Rosmin N and Musta H 2017 Reviews on multilevel converter and modulation techniques Renew. Sustain. Energy Rev. 80 163–74

[2] Tarek M S I, Siam A, Zia M and Rahman M M 2018 A novel five-level inverter topology with reactive power control for grid-connected PV system 2018 International Conference on Smart Grid and Clean Energy Technologies, ICSGCE 2018 (IEEE) pp 101–5

[3] Sinha A, Chandra Jana K and Kumar Das M 2018 An inclusive review on different multi-level inverter topologies, their modulation and control strategies for a grid connected photo-voltaic system Sol. Energy 170 633–57

[4] Al-Badrani H, Feuersanger S and Pacas M 2018 VSI with Sinusoidal Voltages for an Enhanced Sensorless Control of the Induction Machine PCIM Europe 2018, Nuremberg, Germany pp 1199– 205

[5] Shanono I H, Rul N, Abdullah H and Muhammad A 2018 A Survey of Multilevel Voltage Source Inverter Topologies , Controls and Applications Int. J. Power Electron. Drive Syst. 9 1186–201

Electrical Design of a Photovoltaic-Grid System For Electric Vehicles Charging Station

 ABSTRACT:

This work presents a smart method for a photovoltaic grid system for electric vehicles charging station, however, it describes the flow power through a smooth algorithm using Matlab/Simulink environment. The consumption of electric vehicle battery is considered as a daily load for the charging station, indeed, it is highly recommended to predict the periodic power use in the charging station. However, the storage system is ensured through a lithium ion battery, which provides a wider operating temperature and others convenient characteristics. Additionally, the contribution of the electrical grid is also combined in this architecture as a back-up plan for mutual benefits when the photovoltaic power is unable to secure the station needs, on the one hand and on the other hand, when the battery of the charging station is fully charged and the photovoltaic system is able to inject an extra energy in the grid.

KEYWORDS:

1.      Photovoltaic-Grid System (PVGS)

2.      Electric vehicle (EV)

3.      Charging Station (CS)

4.      Dc-dc Converters

5.      Maximum Power Point Tracking (MPPT)

6.      Perturb and Observe (P&O)

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

This paper presents an intelligent process to feed a lithium ion battery in an EVCS architecture. In this regard, the effectiveness of charging the battery through numerous modes of operation has been validated by simulation results, indeed, it is interesting how fast the battery is charging under higher recharge rate. In fact, this work is inspired from a study case of a project with full specifications, for instance, the meteorological data for the PV panels design and the daily need of energy for the EVB to resize the rated capacity of the BSB. However, the contribution of the grid power remains primordial in the structure nonetheless there are some complexity issues related to the used power flow algorithms in the controller unit, and how it effects on the grid, positively and negatively both.

 REFERENCES:

[1] I. Rahman, P. M. Vasant, B. S. M. Singh, M. Abdullah-Al-Wadud, and N. Adnan, “Review of recent trends in optimization techniques for plug-in hybrid, and electric vehicle charging infrastructures,” Renew. Sustain. Energy Rev., vol. 58, pp. 1039–1047, 2016.

[2] A. R. Bhatti, Z. Salam, M. J. B. A. Aziz, K. P. Yee, and R. H. Ashique, “Electric vehicles charging using photovoltaic: Status and technological review,” Renew. Sustain. Energy Rev., vol. 54, pp. 34–47, 2016.

[3] M. Van Der Kam and W. Van Sark, “Smart charging of electric vehicles with photovoltaic power and vehicle-to-grid technology in a microgrid ; a case study,” Appl. Energy, vol. 152, pp. 20–30, 2015.

[4] J. P. Torreglosa, P. García-Triviño, L. M. Fernández-Ramirez, and F. Jurado, “Decentralized energy management strategy based on predictive controllers for a medium voltage direct current photovoltaic electric vehicle charging station,” Energy Convers. Manag., vol. 108, pp. 1–13, 2016.

[5] P. Goli and W. Shireen, “PV powered smart charging station for PHEVs,” Renew. Energy, vol. 66, pp. 280–287, 2014.

Sensor-Less Five-Level Packed U-Cell (PUC5) Inverter Operating in Stand-Alone and Grid-Connected Modes

 ABSTRACT:

In this paper a new mode of operation has been introduced for Packed U-Cell (PUC) inverter. A sensor-less voltage control based on redundant switching states is designed for the PUC5 inverter which is integrated into switching process. The sensor-less voltage control is in charge of fixing the DC capacitor voltage at half of the DC source value results in generating symmetric five-level voltage waveform at the output with low harmonic distortion. The sensor-less voltage regulator reduces the complexity of the control system which makes the proposed converter appealing for industrial applications. An external current controller has been applied for grid-connected application of the introduced sensor-less PUC5 to inject active and reactive power from inverter to the grid with arbitrary power factor while the PUC auxiliary DC bus is regulated only by sensor-less controller combined with new switching pattern. Experimental results obtained in stand-alone and grid-connected operating modes of proposed PUC5 inverter prove the fast response and good dynamic performance of the designed sensorless voltage control in balancing the DC capacitor voltage at desired level.

 

KEYWORDS:

1.      Multilevel Inverter

2.      Packed U-Cell

3.      Sensor-Less Voltage Regulator

4.       PUC5

5.      5-Level Inverter

6.      Power Quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

The PUC5 inverter has been proposed in this paper while the capacitor voltage is balanced without involving any external controller and voltage feedback sensors. The proposed sensor-less voltage controller has been integrated into switching technique to work as open-loop system with reliable results. Moreover, another controller has been designed for the PUC5 inverter to work as unity power factor grid-connected inverter. Low harmonics components in both voltage and current waveforms generated by PUC5, no need to bulky output filters, reliable and good dynamic performance in variable conditions (including change in DC source, load, power amount injected to the grid), requiring no voltage/current sensor in stand-alone mode, low manufacturing costs and miniaturized package due to using less components and etc are interesting advantages of the  introduced PUC5 topology which have been proved by experimental results in both stand-alone and grid-connected modes. The presented PUC5 inverter can be a challenging candidate for conventional photovoltaic application inverters.

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] L. G. Franquelo, J. Rodriguez, J. I. Leon, S. Kouro, R. Portillo, and M. A. M. Prats, "The age of multilevel converters arrives," IEEE Ind. Electron. Mag., vol. 2, no. 2, pp. 28-39, 2008.

[3] C. Cecati, F. Ciancetta, and P. Siano, "A multilevel inverter for photovoltaic systems with fuzzy logic control," IEEE Trans. Ind. Electron., vol. 57, no. 12, pp. 4115-4125, 2010.

[4] M. Seyedmahmoudian, S. Mekhilef, R. Rahmani, R. Yusof, and E. T. Renani, "Analytical modeling of partially shaded photovoltaic systems," Energies, vol. 6, no. 1, pp. 128-144, 2013.

[5] 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.

Real-Time Implementation of a 31-Level Asymmetrical Cascaded Multilevel Inverter for Dynamic Loads

 ABSTRACT:

Among the renewable energy applications, the most popular inverters are cascaded multilevel inverters. Irrespective of numerous benefits these inverters face reliability issues due to the presence of more circuit components in the design. This has been a critical challenge for researchers in designing inverters with enhanced reliability by reducing the total harmonic distortion (THD). This paper proposes a 31-level asymmetric cascaded multilevel inverter for renewable energy applications. The proposed topology produces waveforms consisting of the staircase with a high number of output levels with lesser components with low THD. The investigations on the feasibility and performance of MLI under steady-state, transient, and dynamic load disturbances. The results are validated from a 1.6kW system which provides the proposed inverter.

KEYWORDS:

1.      Multilevel inverter (MLI)

2.       total harmonic distraction (THD)

3.       staircase modulation technique

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

The proposed inverter is tested experimentally with resistive and inductive loads. The output waveforms obtained during the resistive load test clearly show that the phase angle between current and voltage is zero. And the inductive load testing results show that the current is lagging voltage. To test the robustness of the proposed scheme, a load disturbances test is conducted. It is observed that the proposed topology is well stabilized under load disturbances conditions. The presented topology provides seven-level and thirty-one level output voltage with only 6 and 10 switches respectively in asymmetrical conditions. Under simulation a THD value of 3.62% is obtained using SIMULINK. under experimental conditions the computed THD value is 3.7%. The ability of presented MLI topology has been veri_ed using both simulation and experimental setups and the results are demonstrated for both conditions. The suggested topology is appropriate for the integration of medium-voltage renewable energy and power quality improvement in DVR, DStatcom and FACTs.

REFERENCES:

[1] T. Porselvi and R. Muthu, ``Comparison of cascaded H-Bridge, neutral point clamped and _ying capacitor multilevel inverters using multicarrier PWM,'' in Proc. Annu. IEEE India Conf., Dec. 2011, pp. 1_4.

[2] M. A. Hosseinzadeh, M. Sarbanzadeh, E. Sarbanzadeh, M. Rivera, and R. Grégor, ``Back-to-back modi_ed T-type half-bridge module for cascaded multi-level inverters with decreased number of components,'' in Proc. IEEE Int. Conf. Electr. Syst. Aircraft, Railway, Ship Propuls. Road Vehicles Int. Transp. Electri_c. Conf. (ESARS-ITEC), Nov. 2018, pp. 1_6.

[3] J. Rodríguez, J.-S. Lai, and F. Z. Peng, ``Multilevel inverters: A survey of topologies, controls, and applications,'' IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724_738, Aug. 2002.

[4] Y. Suresh, J. Venkataramanaiah, A. K. Panda, C. Dhanamjayulu, and P. Venugopal, ``Investigation on cascade multilevel inverter with symmetric, asymmetric, hybrid and multi-cell con_gurations,'' Ain Shams Eng. J., vol. 8, no. 2, pp. 263_276, 2017.

[5] N. Prabaharan, A. H. Fathima, and K. Palanisamy, ``New hybrid multilevel inverter topology with reduced switch count using carrier based pulse width modulation technique,'' in Proc. IEEE Conf. Energy Convers. (CENCON), Oct. 2015, pp. 176_180.

PWM Sensor-less Balancing Technique for theFifteen-Level PUC Converter

 ABSTRACT:

In this paper, a novel PWM technique insuring the self-balancing of the capacitors voltages has been proposed for the attained nine-level packed U cells (PUC) converter. In the traditional fifteen-level operation, the capacitors voltages have to be maintained around their references using a state variable feedback which requires three sensors, two for the capacitors voltages and one for the load current. By applying the proposed PWM technique to the fifteen-level PUC converter, self balancing of the capacitors voltages is attained, which results in the proposed nine-level converter. The proposed balancing technique is achieved without any closed loop regulation or sensors. The proposed concept has been verified by mean of simulations performed in the Matlab Simulink environments. Simulation results show that even under severe DC bus voltage and load parameters variations, the capacitors voltages remains around their required values. Harmonics contents of load current depend on the modulating signal frequency. Moreover, even under low frequencies, the total harmonics distortion remains reduced.

KEYWORDS:

1.      Packed U cells

2.      Multilevel converters

3.      Self balancing

4.      PWM technique

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

A sensor-less self balancing PWM technique applied to the fifteen-level PUC inverter was presented in this paper. It allows a fast open loop regulation of the PUC inverter capacitors voltages without using any additional circuit. Indeed, the self balancing is achieved without using any state variable feedback or sensors. The proposed concept was verified by simulation results.

REFERENCES:

[1] Y. Ounejjar and K. Al-Haddad "A novel high energetic efficiency multilevel topology with reduced impact on supply network", The 34^th Annual Conference of the IEEE Industrial Electronics Society, pp.489-494, 10-13 November 2008, Orlando, Florida, USA

[2]- Ounejjar, Y., K. Al-Haddad et L. Gregoire.. "Packed U Cells Multilevel Converter Topology: Theoretical Study and Experimental Validation". IEEE Transactions on Industrial Electronics, vol. 58, n°4, p.1294-1306, (April 2011).

[3] X. h. Zhang and W. k. Yue, "Neutral point potential balance algorithm for three-level NPC inverter based on SHEPWM," in Electronics Letters,vol. 53, no. 23, pp. 1542-1544, 11 9 2017

[4] M. Sleiman, K. Al-Haddad, H. F. Blanchette and H. Y. Kanaan, "Insertion Index Generation Method Using Available Leg–Average Voltage to Control Modular Multilevel Converters," in IEEE Transactions on Industrial Electronics, vol. PP, no. 99, pp. 1-1.

[5] I. López et al., "Modulation Strategy for Multiphase Neutral-Point- Clamped Converters," in IEEE Transactions on Power Electronics, vol. 31, no. 2, pp. 928-941, Feb. 2016.

Multilevel Inverter Topologies with ReducedDevice Count: A Review

 

ABSTRACT:

 Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of highpower medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analysed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application.

KEYWORDS:

1.      Multilevel inverters

2.      Reduced device count

3.      Even power distribution

4.       Fundamental switching frequency operation

5.      Source configuration

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

As multilevel inverters continue to gain increasing importance for both high power and low power applications, many researchers have proposed specific topological solutions for intended applications. Also, newer multilevel topologies have been proposed, offering high output resolution with a reduced number of power switches. In this paper, a review of nine reduced device count multilevel topologies is presented. Based on the review, it can be concluded that in the process of reducing the power switch count, various compromises are involved such as:

i. Increased voltage rating of semiconductor switches.

ii. Requirement of bidirectional switches

iii. Increased number of sources and/or requirement of asymmetric input DC levels.

iv. Loss of modularity.

v. Reduced number of redundant states.

vi. Complex modulation / control schemes.

vii. Difficulty in possibility of charge balance control.

In this paper, qualitative and quantitative features of RDC-MLI topologies have been discussed and a comparison has been made so as to facilitate a well-informed selection of topology for a given application. In addition, the paradigm presented in the paper will also help to evaluate the RDC-MLI topologies that will be proposed in future.

REFERENCES:

[1] Espinoza, J. R.;, "Inverters," Power Electronics Handbook, MH Rashid (Ed.), pp. 225-269, 2001.

[2] Abbott, D.;, "Keeping the Energy Debate Clean: How Do We Supply the World's Energy Needs?," Proceedings of the IEEE , vol.98, no.1, pp.42-66, Jan. 2010.

[3] Xinghuo, Y.; Cecati, C.; Dillon, T.; SimoÞes, M.G.;, "The New Frontier of Smart Grids," Industrial Electronics Magazine, IEEE , vol.5, no.3, pp.49-63, Sept. 2011.

[4] Daher, S.;,“ Analysis, design and implementation of a high efficiency multilevel converter for renewable energy systems” , PhD Dissertation Submitted to Kassel University, Kassel, Germany, 2006, Available: http://www.uni-kassel.de/upress/online/frei/978-3-89958-236-9.volltext.frei.pdf.

[5] Franquelo, L.G.; Rodriguez, J.; Leon, J.I.; Kouro, S.; Portillo, R.; Prats, M.A.M.; , "The age of multilevel converters arrives," Industrial Electronics Magazine, IEEE , vol.2, no.2, pp.28-39, June 2008.