Comparison of Fuzzy and ANFIS Controllers for Asymmetrical 31-Level Cascaded Inverter With Super Imposed Carrier PWM Technique

ABSTRACT:

 The modified topology for an asymmetrical 31-level cascaded inverter is analyzed with less number of DC voltage sources, power diodes, and power electronic knobs. The Super Imposed Carrier Pulse Width Modulation (SIC-PWM) is proposed for a 31-level asymmetrical modified cascaded inverter topology to reduce the Total Harmonic Distortions (THD). The Fuzzy logic controller (FLC) and Adaptive Neuro-Fuzzy Inference System (ANFIS) are suggested for a 31-level asymmetrical modified cascaded inverter topology to control the root mean square (RMS) voltage. These controllers help in maintaining the output voltage constant even when there is a change in input voltage to the inverter. This study aims to compare Fuzzy logic and ANFIS controllers by applying them to the 31-level cascaded inverter. Using both the controllers the inverter is controlled and its performance is compared using a step response tool in MATLAB. The study of the proposed modified 31-level Asymmetrical cascaded inverter is carried out to evaluate the THD without and with Fuzzy logic and ANFIS controller. Using the step response tool, Settling Time, Overshoot, RMS Voltage values, Peak Time, Peak value, and Rise Time were evaluated and compared for Fuzzy and ANFIS controlled 31-level asymmetrical cascaded inverter. The THD value for without a controller is 4.97%, with the fuzzy logic controller is 4.15% and with ANFIS controller is 3.77%. In both MatLab and real-time simulation, total harmonic distortion (THD) is observed to be the almost same and is lower than 5% which is under IEEE standards. The performance of Fuzzy and ANFIS controlled 31-level asymmetrical cascaded inverter is evaluated and compared with the use of MATLAB/Simulink and the same is done with Real-Time simulation using OPAL-RT 5700.

 KEYWORDS:

1.      Asymmetrical cascaded inverter

2.      Super imposed carrier PWM technique

3.      Total harmonic distortion

4.      Adaptive neuro-fuzzy inference system (ANFIS)

5.      Fuzzy logic controller (FLC)

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure 1. The fundamental circuit diagram of symmetrical and asymmetrical cascaded inverter.

 EXPECTED SIMULATION RESULTS:

 

Figure 2. Load wide output voltage for 31-level modified asymmetrical inverter.

 

Figure 3. Output Current through load for 31-level modified asymmetrical inverter.

Figure 4. FFT Analysis for output voltage of 31-level modified asymmetrical inverter.

 

Figure 5. Reference and output RMS voltage for 31-level inverter with fuzzy.

Figure 6. Output voltage across load with Fuzzy logic controller.

Figure 7. FFT analysis for 31-level inverter with fuzzy.

Figure 8. Output voltage across load with ANFIS controller.

CONCLUSION:

The proposed modified 31-level Asymmetrical cascaded inverter with and without Fuzzy logic and ANFIS controller is presented in this paper, demonstrating a substantial change in THD percentages and RMS voltage control. The proposed modified 31-level Asymmetrical cascaded inverter with Fuzzy logic and ANFIS controller is designed in MATLAB/ SIMULINK and verified in Real-Time simulation using OPAL-RT 5700. By using Super Imposed Carrier Pulse Width Modulation (SIC-PWM) with and without the controller, the RMS output voltage is controlled and THD is decreased. The performance of step response parameter values is evaluated and compared for Fuzzy and ANFIS controlled 31-level Asymmetrical cascaded inverter. The dynamic conditions were also analyzed for different DC source voltages and variable resistive loads, the RMS output voltage is controlled and maintained constant (i.e., RMS value is 21.98V for Fuzzy and 22.21V for ANFIS). Using the analytical solution for a 31-level cascaded inverter, it has been identified that the THD value for without a controller is 4.97%, with the fuzzy logic controller is 4.15% and with ANFIS controller is 3.77%. As compared to the Fuzzy logic controller, the ANFIS controller gives better performance. i.e., the RMS Voltage is controlled and settled in less settling time.

REFERENCES:

[1] K. K. Gupta, A. Ranjan, P. Bhatnagar, L. K. Sahu, and S. Jain, ``Multilevel inverter topologies with reduced device count: A review,'' IEEE Trans. Power Electron., vol. 31, no. 1, pp. 135_151, Jan. 2016.

[2] W. A. Halim, S. Ganeson, M. Azri, and T. T. Azam, ``Review of multi- level inverter topologies and its applications,'' J. Telecommun., Electron. Comput. Eng., vol. 8, no. 7, pp. 51_56, 2016.

[3] R. A. Krishna and L. P. Suresh, ``A brief review on multilevel inverter topologies,'' in Proc. Int. Conf. Circuit, Power Comput. Technol. (ICCPCT), Mar. 2016, pp. 1_6.

[4] J. Venkataramanaiah, Y. Suresh, and A. K. Panda, ``A review on symmetric, asymmetric, hybrid and single DC sources based multilevel inverter topologies,'' Renew. Sustain. Energy Rev., vol. 76, pp. 788_812, Sep. 2017, doi: 10.1016/j.rser.2017.03.066.

[5] F. Dijkhuizen, ``Multilevel converters: Review, form, function and motivation,'' in Proc. Ever, 2012, p. 7.

A Two-stage Single-phase Grid-connected Solar-PV System with Simplified Power Regulation

ABSTRACT:

 This study focuses on the design and development of a simplified active power regulation scheme for a two-stage single-phase grid-connected solar-PV (SPV) system with maximum power point (MPP) estimation. It aims to formulate and test an improvised new control scheme to estimate the real-time MPP of the PV panel and operate only at either the MPP or on the right-hand side (RHS) of the PV characteristics of the panel. A simple active power regulatory control scheme was formulated to provide frequency control services to a single-phase grid without using an energy storage device. The plant operator provides the reserve fraction as the input for the active power regulation controller. At any time, the reserve fraction is used to determine the magnitude of the reference power to be extracted from the PV panel for injection into the grid. A simple PI controller was used to track the calculated reference power. The different modes of operation of the regulatory scheme are presented in detail. All the above control schemes are integrated and implemented through appropriate switching of the DC-DC converter alone. The DC-AC converter maintains the DC link voltage and unity power factor at the single-phase grid terminals. The proposed control schemes were tested on a 250 Wp solar panel feeding power to a 230 V, 50 Hz single-phase grid through a two-stage converter. The entire scheme was modeled using the Matlab/Simulink platform, and the same was validated by hardware experimentation using Chroma Solar Simulator and NI my RIO controller under varied irradiation, temperature, and reserve fractions. The simulation and hardware results are compared and reported.

 KEYWORDS:

1.      Solar photo voltaic (SPV)

2.      Maximum power point (MPP)

3.      Right hand side (RHS)

4.      Power regulation

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1 Two-stage grid-connected single-phase solar-PV system with control logic

 EXPECTED SIMULATION RESULTS:

 

Fig. 2 Variation in maximum power estimation and grid power under varied irradiation and temperature with zero reserve

 

Fig. 3 Variation in maximum power estimation and grid  power under varied irradiation at constant temperature 25^oC with reserve fraction

Fig. 4 Variation in maximum power estimation and grid power under varied irradiation and temperature with the change in reserve fraction

Fig. 5 Grid injected current corresponding to the various irradiation, temperature, and reserve fraction

 

Fig. 6 Grid voltage in p.u. and grid injected current

 CONCLUSION:

The proposed simplified active power control with reserve fraction over the entire operating range from near-zero to 100 % of the available MPP was tested and reported for various operating conditions. The RHS operating point of the SPV was maintained under all operating conditions with a specified reserve fraction. This was validated by observing the operating voltage of the SPV, along with the results obtained through the solar simulator. Further, the power quality was ensured at the grid terminals in the proposed scheme by maintaining the THD and zero reactive power exchange. The essential findings and results required for supporting the proposed scheme were provided by modeling and simulating a grid-connected 250 Wp solar-PV system. Subsequently, experimental results obtained by implementing a prototype setup with the same specifications in the laboratory helped to validate the effectiveness of the proposed active power regulation scheme.

 REFERENCES:

 [1] N Gelsora, N Gelsorb, T Wangmob, et al. Solar energy on the Tibetan plateau: Atmospheric influences. Solar Energy, 2018, 173: 984-992.

[2] E Lorenzani, G Migliazza, F Immovilli, et al. CSI and CSI7 current source inverters for modular transformerless PV inverters. Chinese Journal of Electrical Engineering, 2019, 5(2): 32-42.

[3] X Zhang, Q Gao, Y Hu, et al. Active power reserve photovoltaic virtual synchronization control technology. Chinese Journal of Electrical Engineering, 2020, 6(2): 1-6.

[4] F Zhang, D Jiang, K Xu, et al. Two-stage transformerless dual-buck PV grid-connected inverters with high efficiency. Chinese Journal of Electrical Engineering, 2018, 4(2): 36-42.

[5] E I Batzelis, S A Papathanassiou. A method for the analytical extraction of the single-diode PV model parameters. IEEE Trans. Sustain. Energy, 2016, 7(2): 504-512.

A Novel Single-Phase Five-Level Transformer-less Photovoltaic (PV) Inverter

 ABSTRACT:

 Multilevel inverters are preferred solutions for photovoltaic (PV) applications because of lower total harmonic distortion (THD), lower switching stress and lower electromagnetic interference (EMI). In order to reduce the leakage current in the single-phase low-power PV inverters, a five-level transformer-less inverter is proposed in this paper. A total of eleven switches are required, while six of them only withstand a quarter of the dc-bus voltage, so the costs for them are low. Another four switches are turned on or off at the power line cycle, the switching losses for them are ignored. In addition, the flying-capacitors (FCs) voltages are only a quarter of the dc-bus voltage, and they are balanced at the switching frequency, which further reduces the system investment. The experimental results based on a 1 kW prototype show that the proposed modulation strategy can balance the FCs voltages at Vdc/4 very well. And the leakage current can be reduced to about 27 mA under both active and reactive operations, which satisfies the VDE 0126-1-1 standard.

 KEYWORDS:

1.      Leakage current

2.      Multilevel inverter

3.      Pulse width modulation

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Proposed single-phase five-level inverter topology.

 EXPECTED SIMULATION RESULTS:

 

                                         Fig. 2. Simulation waveforms under asymmetry filter inductance conditions. (a)

L1=1.6 mH and L2=1.44 mH. (a) L1=1.6 mH and L2=1.28 mH.

 

Fig. 3. Waveforms of output voltage VAB, Vout and current iout.

Fig. 4. Waveforms of output voltage VAB and FC voltages VC1, VC2.

Fig. 5. Waveforms of VAN, VBN, VCM and ileakage.

Fig. 6. Waveforms of VAN, VBN and VCM in the positive half cycle.

Fig. 7. Waveforms of VAN, VBN and VCM in the negative half cycle.

 

Fig. 8. Waveforms of VAB, VC1 and iout when θ is 35 degrees.

Fig. 9. Transient experiment in load.

 

CONCLUSION:

In this paper, a single-phase five-level transformer-less inverter and its modulation strategy for the PV systems are proposed. It adopts the symmetrical filter inductor configuration. The difference from the traditional FC-based topologies is that the FCs voltages are controlled at Vdc/4. Through the combination of dc-bus voltage and FCs voltages, the CM voltage is theoretically maintained at a constant value during the whole power frequency of unite grid, and then the leakage current is reduced. The two FCs voltages can be balanced at Vdc/4 automatically at the switching frequency through the selection of the redundant switching states. Finally, the volume and investment cost of the FCs are decreased. The theoretical analysis and experimental verifications are presented. In conclusion, the proposed topology and modulation strategy can ensure a constant CM voltage without any high-frequency components throughout the power frequency cycle. Consequently, the leakage current can be significantly reduced below 300 mA, which meets the specification in the standard VDE-0126-1-1.

REFERENCES:

[1] M. Pahlevani, S. Eren, J. M. Guerrero and P. Jain, “A hybrid estimator for active/reactive power control of single-phase distributed generation systems with energy storage,” IEEE Trans. Power Electron., vol. 31, no. 4, pp. 2919-2936, Apr. 2016.

[2] E. Rebello, D. Watson and M. Rodgers, “Performance analysis of a 10 MW wind farm in providing secondary frequency regulation: experimental aspects,” IEEE Trans. Power Syst, vol. 34, no. 4, pp. 3090-3097, Jul. 2019.

[3] H. Wang, L. Kou, Y. Liu and P. C. Sen, “A seven-switch five-level active-neutral-point-clamped converter and its optimal modulation strategy,” IEEE Trans. Power Electron., vol. 32, no. 7, pp. 5146-5161, Jul. 2017.

[4] X. Guo, X. Zhang, H. Guan, T. Kerekes and F. Blaabjerg, “Three-phase ZVR topology and modulation strategy for transformerless PV system,” IEEE Trans. Power Electron., vol. 34, no. 2, pp. 1017-1021, Feb. 2019.

[5] W. Li, Y. Gu, H. Luo, W. Cui, X. He and C. Xia, “Topology review and derivation methodology of single-phase transformerless photovoltaic inverters for leakage current suppression,” IEEE Trans. Ind. Electron., vol. 62, no. 7, pp. 4537-4551, Jul. 2015.

A Novel Design of Hybrid Energy Storage System for Electric Vehicles

ABSTRACT:

 In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles, a new hybrid energy storage system for electric vehicle is designed in this paper. For the hybrid energy storage system, the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor. At the same time, the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles. As a result, the size of battery is reduced, and the power quality of the hybrid energy storage system is optimized. Finally, the effectiveness of the proposed method is validated by simulation and experiment.

 KEYWORDS:

1.      Hybrid energy storage system

2.      Integrated magnetic structure

3.      Electric vehicles

4.      DC-DC converter

5.      Power dynamic limitation

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1 Topology of the hybrid energy storage system

EXPECTED SIMULATION RESULTS:

 

(a) Power command and actual power

 

(b) Power of the super-capacitor and Li-ion battery

Fig.2 Simulation results of the proposed HESS

(a) Battery current

 

(b) Super-capacitor current

 

(c) Load current

 

(d) Load voltage

Fig.3 Simulation results of the proposed HESS applied on electric vehicles

 

CONCLUSION:

In this paper, a new hybrid energy storage system for electric vehicles is designed based on a Li-ion battery power dynamic limitation rule-based HESS energy management and a new bi-directional DC/DC converter. The system is compared to traditional hybrid energy storage system, showing it has significant advantage of reduced volume and weight. Moreover, the ripple of output current is reduced and the life of battery is improved.

REFERENCES:

[1] Zhikang Shuai, Chao Shen, Xin Yin, Xuan Liu, John Shen, “Fault analysis of inverter-interfaced distributed generators with different control schemes,” IEEE Transactions on Power Delivery, DOI: 10. 1109/TPWRD. 2017. 2717388.

[2] Zhikang Shuai, Yingyun Sun, Z. John Shen, Wei Tian, Chunming Tu, Yan Li, Xin Yin, “Microgrid stability: classification and a review,” Renewable and Sustainable Energy Reviews, vol.58, pp. 167-179, Feb. 2016.

[3] N. R. Tummuru, M. K. Mishra, and S. Srinivas, “Dynamic energy management of renewable grid integrated hybrid energy storage system, ” IEEE Trans. Ind. Electron., vol. 62, no. 12, pp. 7728-7737, Dec. 2015.

[4] T. Mesbahi, N. Rizoug, F. Khenfri, P. Bartholomeus, and P. Le Moigne, “Dynamical modelling and emulation of Li-ion batteries- supercapacitors hybrid power supply for electric vehicle applications, ” IET Electr. Syst. Transp., vol.7, no.2, pp. 161-169, Nov. 2016.

[5] A. Santucci, A. Sorniotti, and C. Lekakou, “Power split strategies for hybrid energy storage systems for vehicular applications, ” J. Power Sources, vol. 258, no.14, pp. 395-407, 2014.

Seven-Level Inverter with Reduced Switches for PV System Supporting Home-Grid and EV Charger

ABSTRACT:

This paper proposes a simple single-phase new pulse-width modulated seven-level inverter architecture for photovoltaic (PV) systems supporting home-grid with electric vehicle (EV) charging port. The proposed inverter includes a reduced number of power components and passive elements size, while showing less output-voltage total harmonic distortion (THD), and unity power factor operation. In addition, the proposed inverter requires simple control and switching strategies compared to recently published topologies. A comparative study was performed to compare the proposed inverter structure with the recent inverter topologies based on the number of components in the inverter circuit, number of components per output-voltage level, average number of active switches, THD, and operating efficiency as effective parameters for inverter performance evaluation. For design and validation purposes, numerical and analytical models for a grid-tied solar PV system driven by the proposed seven-level inverter were developed in MATLAB/Simulink environment. The inverter performance was evaluated considering grid-integration and stand-alone home with level-2 AC EV charger (3–6 kW). Compared with recently published topologies, the proposed inverter utilizes a reduced number of power components (7 switches) for seven-level terminal voltage synthesis. An experimental prototype for proposed inverter with the associated controller was built and tested for a stand-alone and grid-integrated system. Due to the lower number of ON-switches, the inverter operating efficiency was enhanced to 92.86% with load current THD of 3.43% that follows the IEEE standards for DER applications.

KEYWORDS:

1.      DC-AC converter

2.      Electric vehicles

3.      Home grid

4.      Maximum power point tracking (MPPT)

5.      Multilevel inverter

6.      Photovoltaic (PV) system

7.      Seven-level inverter

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:  

Figure 1. Circuit configuration of solar PV system in integrated with the grid and EV loads via the proposed 7level-inverter.

 EXPECTED SIMULATION SYSTEM:

(a) Solar irradiation

(b) PV current

(c) PV voltage

Figure 2. Cont

time(s)

(d)PV power

Figure 3. the pv panel current, voltage, and power.

 Figure 4. multi- Level inverter output voltage.

Figure 5. the injected current, voltage, and power variation. (a) Grid voltage and current; (b) Grid injected power.

 

Figure 6. The reference and actual injected currents of the seven-level inverter at irradiance variation.

 

Figure 7. Simulation results of the proposed 7-level inverter as level-2 EV charger (240 V, 3:6 kW); (a) loading profile, (b) multilevel output voltage, and (c) inverter voltage/pulsating current

Figure 8. Simulation results of the proposed 7-level inverter for house loads voltage control (2 kW). (a) Load reference and actual voltages, (b) Load voltage and current

CONCLUSION:

 This paper has presented a new topology of a single-phase seven-level inverter as an interface for grid-integrated and stand-alone solar PV systems. The circuit configuration This paper has presented a new topology of a single-phase seven-level inverter as an interface for grid-integrated and stand-alone solar PV systems. The circuit configuration This paper has presented a new topology of a single-phase seven-level inverter as an interface for grid-integrated and stand-alone solar PV systems. The circuit configuration and operation principle of the proposed inverter have been presented in detail a long with    the switching patterns and control strategy. A comparative study between the proposed inverter structure and the recent MLI topologies is enriched to reveal the features of the proposed inverter. The proposed MLI structure considers a reduced number of power switches, NC/L, and NAVG/Pole, which enhances the inverter operating efficiency and decreases its cost. Only seven switches have been utilized to synthesis voltage waveform of seven levels at the output terminals. The performance of the proposed inverter and associated control was investigated for grid-integrated and stand-alone PV systems based on simulation and experimental tests. The test platform includes a boost converter with MPPT control, which feeds the front-end of the proposed MLI. The results show that the proposed inverter exhibits an improved steady state response, and minimum settling time (i.e., 5 ms). THD of both voltage and current waveforms during grid-integration and stand-alone operations is 3.43%, which follows the IEEE-1547 harmonic standards for DER applications. In addition, the inverter offers a high operating efficiency of 92.86%, compared to most of the recently published topologies surveyed in this paper.

REFERENCES:

1. Solangi, K.; Islam, M.; Saidur, R.; Rahim, N.; Fayaz, H. A review on global solar energy policy. Renew. Sustain. Energy Rev. 2011, 15, 2149–2163. [CrossRef]

2. Ali, A.I.; Sayed, M.A.; Mohamed, E.E. Modified efficient perturb and observe maximum power point tracking technique for grid-tied PV system. Int. J. Electr. Power Energy Syst. 2018, 99, 192–202. [CrossRef]

3. Sayed, M.A.; Mohamed, E.; Ali, A. Maximum Power Point Tracking Technique for Grid tie PV System. In Proceedings of the 7th International Middle-East Power System Conference, (MEPCON’15), Mansoura University, Dakahlia Governorate, Egypt, 15–17 December 2015.

4. Ali, A.I.; Mohamed, E.E.; Sayed, M.A.; Saeed, M.S. Novel single-phase nine-level PWM inverter for grid connected solar PV farms. In Proceedings of the 2018 International Conference on Innovative Trends in Computer Eng. (ITCE), Aswan, Egypt, 19–21 February 2018; IEEE: Piscataway, NJ, USA, 2018; pp. 345–440.

5. Youssef, A.-R.; Ali, A.I.; Saeed, M.S.; Mohamed, E.E. Advanced multi-sector P&O maximum power point tracking technique for wind energy conversion system. Int. J. Electr. Power Energy Syst. 2019, 107, 89–97.