Fuzzy Logic Control for Solar PV Fed ModularMultilevel Inverter Towards Marine Water Pumping Applications

 ABSTRACT:

This paper presents the design and implementation of Modular Multilevel Inverter (MMI) to control the Induction Motor (IM) drive using intelligent techniques towards marine water pumping applications. The proposed inverter is of eleven levels and has the ability to control the speed of an IM drive which is fed from solar photovoltaics. It is estimated that the energy consumed by pumping schemes in an onboard ship is nearly 50% of the total energy. Considering this fact, this paper investigates and validates the proposed control design with reduced complexity intended for marine water pumping system employing an induction motor (IM) drive and MMI. The analysis of inverter is carried out with Proportional-Integral (PI) and Fuzzy Logic (FL) based controllers for improving the performance. A comparative analysis has been made with respect to better robustness in terms of peak overshoot, settling time of the controller and Total Harmonic Distortion (THD) of the inverter. Simulations are undertaken in MATLAB/Simulink and the detailed experimental implementation is conducted with Field Programmable Gate Array (FPGA). The results thus obtained are utilized to analyze the controller performance, improved inverter output voltage, reliable induction motor speed control and power quality improvement by reduction of harmonics. The novelty of the proposed control scheme is the design and integration of MMI, IM drive and intelligent controller exclusively for marine water pumping applications.

KEYWORDS:

1.      Field programmable gate array

2.      Fuzzy logic controller

3.      Induction motor drive

4.      Modular multilevel inverter

5.      Proportional-integral

6.      Total harmonic distortion

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. Schematic Diagram Of The Proposed 11-Level Inverter.Aq

 EXPECTED SIMULATION RESULTS:

Figure 2. Speed Response Of Pi Controller At 1000 Rpm.

 

Figure 3. Speed Response Of Flc At 1000 Rpm.

 

Figure 4. Harmonic Analysis With Pi Controller.

 

Figure 5. Harmonic Analysis With Fl Controller.

 

Figure 6. Output Voltage Waveform Of An 11 Level Inverter.

 

CONCLUSION:

The relevance of the proposed work is to provide high quality of input power to the inverter drive pertaining to marine water pumping applications. A solar PV fed MMI for speed control of induction motor drive has been examined at steady state and dynamic behaviors to investigate its suitability for water pumping system intended for the marine applications. The solar PV array is connected with the proposed inverter when is then fed to an induction motor. The motor speed is sensed and feedback is given to the controller for generating optimal PWM pulses for the inverter switches. The motor is started gradually and the speed is increased to achieve reference speed with aid of PI and FL based controllers. The performance of PI and FL controllers for a feasible operation is verified and results are compared in both simulation and experiment. The results ensure that the FL based controller provides fast settling time and reduced harmonics when compared with the PI controller. The main impact of the proposed control scheme is to reduce the steady-state error of the induction motor speed control and deteriorate harmonics at the output voltage of modular multilevel inverter. On considering the number of components required for the proposed MMI, the Table 3 illustrates the comparative analysis on the number of semiconductor switches required for the design of MMI along with those inverters available in the literature.

The source, converter, load, controller and grid are the major components of a DC microgrid. A microgrid is normally referred as a standalone autonomous system to generate power by the community and for the community regions. In the proposed system, the entire component cited for DC microgrid is present and performs its function effectively. The appropriate estimation of power generated and power used is the future scope.

REFERENCES:

[1] H. Lan, Y. Bai, S.Wen, D. C. Yu, Y.-Y. Hong, J. Dai, and P. Cheng, ``Modeling and stability analysis of hybrid PV/diesel/ESS in ship power system,'' Inventions, vol. 1, no. 5, pp. 1_16, 2016, doi: 10.3390/inventions1010005.

[2] S. G. Jayasinghe, L. Meegahapola, N. Fernando, Z. Jin, and J. M. Guerrero, ``Review of ship microgrids: System architectures, storage technologies and power quality aspects,'' Inventions, vol. 2, no. 4, pp. 1_19, 2017, doi: 10.3390/inventions2010004.

[3] R. Kumar and B. Singh, ``Single stage solar PV fed brushless DC motor driven water pump,'' IEEE J. Emerg. Sel. Topics Power Electron., vol. 5, no. 3, pp. 1337_1385, Sep. 2017, doi: 10.1109/JESTPE.2017.2699918.

[4] S. Shukla and B. Singh, ``Single-stage PV array fed speed sensorless vector control of induction motor drive for water pumping,'' IEEE Trans. Ind. Appl., vol. 54, no. 4, pp. 3575_3585, Jul./Aug. 2018, doi: 10.1109/TIA.2018.2810263.

[5] C.-L. Su, W.-L. Chung, and K.-T. Yu, ``An energy-savings evaluation method for variable-frequency-drive applications on ship central cooling systems,'' IEEE Trans. Ind. Appl., vol. 50, no. 2, pp. 1286_1297, Mar./Apr. 2014, doi: 10.1109/TIA.2013.2271991.

Fractional Order Notch Filter for Grid-Connected Solar PV System with Power Quality Improvement

 ABSTRACT:

 This paper deals with the development of fractional order notch filter (FONF) for a grid-connected solar photovoltaic (PV) system. The developed FONF control approach is used to estimate fundamental active constituents from the distorted load currents and hence gating pulses for operating voltage source converter (VSC) are used in the PV system. This control approach for the grid-connected solar PV system is designed to achieve several purposes such as feeding active power demand of load/grid and counter current related power quality issues at common connecting point. The power quality issues taken into consideration are harmonics distortion, reactive power burden on the system and unbalancing of connected loads. The FONF based control proposes a modified structure of an integer order notch filter. The integer order filters have limitation due to fixed integrator and differentiator term. In FONF, the power of integrator used in a notch filter, can be modified according to the application required for obtaining accurate response of the system. A prototype of the grid-connected solar PV system is developed in the laboratory using IGBTs based VSC and dSPACE MicroLabBox (DS-1202) to demonstrate the behaviour of the FONF based control. Simulation and experimental results are obtained for steady state and unbalanced loads with variation in solar irradiance. The harmonic distortions in the system are observed as per the IEEE-519 standard.

 KEYWORDS:

1.      Solar photovoltaic generation

2.      Fractional order control

3.      Notch filter

4.      Harmonics

5.      Power quality

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

 

Fig. 1 System configuration of grid connected solar PV system.

EXPECTED SIMULATION RESULTS:

 

 

Fig. 2 Bode plot comparison of IONF (α=1, β=1, ξ=0.1 and α=1, β=1, ξ=1) and FONF (α=1.2, β=0.8, ξ=0.5) with different values of fractional parameters.

Fig. 3 Comparative performance of IONF and FONF in converging active weight component.

Fig. 4 Convergence of fundamental active components using FONF, NLMS and NLMF under (a) steady state and (b) unbalanced loading conditions.

 

Fig. 5 Harmonic spectra of (a) grid current iga using FONF (b) grid current iga using NLMS (c) grid current iga using NLMF (d) load current ila.

Fig. 6 Harmonic spectrum of grid current with different frequency components using FONF controller.

 

 

Fig. 7 Harmonic spectrum under nonlinear load with R-C parallel branch using FONF controller (a) grid current, iga (b) load current, ila.

 

CONCLUSION:

 A three-phase grid connected solar photovoltaic system with FONF based control has been proposed in this work. The FONF control has been designed to accomplish twin functions of the grid-connected PV system viz. delivering active power to the load/grid and alleviating current related power quality issues at PCC. Numerous power quality issues such as harmonics distortion in the grid current, reactive power demand of the load and unbalancing load currents have been solved by the developed control system. The FONF control has been found suitable in terms of its flexibility to alter power of integrator used in the notch filter and asymmetrical gain response curve, which is not possible in case of integer order notch filter. It has been observed from the Bode plot that sharpness of developed FONF does not alter by increasing the value of damping ratio once fractional gains are appropriately decided. Moreover, this control presents fast response when compared with integer order notch filter. Performances of FONF controller have been confirmed at steady state and unbalanced load along with variation in solar irradiance considered. Experimental results demonstrate performance of FONF controller in maintaining 3.2% THD in the grid current, which is in accordance with the IEEE-519 standard for the grid interfaced PV system.

REFERENCES:

[1] A. Reinders, P. Verlinden, W. Sark and A. Freundlich, Photovoltaic Solar Energy: From Fundamentals to Applications, Hoboken, NJ, USA, Wiley, 2017.

[2] R. Precup, T. Kamal, S. Z. Hassan, Solar Photovoltaic Power Plants: Advanced Control and Optimization Techniques, Gateway East Singapore, Springer, 2019.

[3] M. K. Hairat, S. Ghosh, “100GW solar power in India by 2022 – A critical review”, Rene. Sustain. Ener. Rev., vol. 73, pp.1041-1050, 2017.

[4] N. Priyadarshi, S. Padmanaban, P. K. Maroti and A. Sharma, “An extensive practical investigation of FPSO-based MPPT for grid integrated PV system under variable operating conditions with anti-islanding protection,” IEEE Sys. Journal, vol. 13, no. 2, pp. 1861-1871, June 2019.

[5] N. Mukundan C. M., Y. Singh, S. Naqvi, B. Singh and J. Pychadathil, “Multi-objective solar power conversion system with MGI control for grid integration at adverse operating conditions,” IEEE Trans. Sust. Energy, vol. 11, no. 4, pp. 2901-2910, 2020.

 

 

Enhanced Power Quality PV-Inverter with Leakage Current Suppression for Three-Phase SECS

ABSTRACT:

 This paper presents an enhanced power quality solar photovoltaic (PV) inverter enabling common-mode leakage current elimination. A three-phase transformer-less solar energy conversion system (SECS) is considered here, which, along with peak active-power production from PV-array, ensures different power quality improvement capabilities such as grid current harmonics mitigation, grid-currents balancing, while also offering the grid reactive power support. Unlike conventional power quality inverters, this strategy is a robust with respect to abnormalities in grid-voltages at far radial ends, and does not compromise with the leakage currents caused by parasitic-capacitance of PV-array with ground. Common practice in the PV inverter power quality control is to neglect the PV leakage-currents, however, they considerably affect the system performance by deteriorating the power quality and causing the safety issues of operating personnel. The standards VDE-00126 and NB/T-32004, therefore, compel the transformer-less PV-systems to operate with leakage current under 300mA range. Various simulation and test results show the satisfactory performance of the presented strategy, even under various grid-side abnormalities. The comparative analysis with state-of-art techniques shows the effectiveness of the strategy. Under all test conditions, the harmonics in grid-currents are observed within limits as per the IEEE-519 and IEC-61727 standards, while the PV leakage-currents are maintained well within the range recommended by VDE-00126 standard.

 KEYWORDS:

 

1.      Common mode voltage (CMV)

2.      Harmonics

3.      Kalman filter (KF)

4.      Leakage Currents

5.      Power quality and Voltage source Converter (VSC)

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Fig. 1. Schematic block diagram of solar energy conversion system

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. System response at unbalanced nonlinear loads (a) vs, is, iL, VAN, VBN, VCN and VCM , (b) ileak, vDVR, iDVR, VDC, VPV, PPV, Pgrid

 

Fig. 3. System response at abnormal grid voltages (a) vs, is, iL, vDVR, iDVR, VCM , ileak at harmonically polluted grid voltages and (b) vs, is, iL, Qg, VDC, VCM, ileak at unbalanced faults in grid side network

 

Fig. 4. System response at nonlinear loads (a) Conventional control (b) Control strategy for H9 converter, (c) Presented control, (d) Harmonic spectra of grid current with multi-PR control, (e) Harmonic spectra of grid current with presented control, (f) Comparative chart with state-of-art strategies

 

Fig. 5. Comparative response of the SECS using (a) Multi-PR controller (b) Presented controller

                                       

 

Fig. 6. System performance under nonlinear loads with load unbalancing event (a) vsab, isa, iLa and ivsca, (b) vsbc, isb, iLb and ivscb, (c) vsab and FFT of vsab, (d) VDC, Ipv, ivsca and isa , (e) vsca, isc, iLc and Ileak, and (f) isa and FFT of isa

 

CONCLUSION:

An effective Kalman state-estimator based controller for two-stage grid connected solar photovoltaic system has been presented, to address the power quality issues in the grid under normal/abnormal conditions, while also ensuring low leakage currents as per the VDE-00126 and NB/T-32004 standards. The common practice in power quality PV-inverters, is to neglect the solar PV parasitic capacitance, however, they considerably affect the system performance by alleviating leakage currents, increasing grid harmonic currents, while increasing the safety concerns of the operating personnel. The high leakage currents in the system are avoided here, while also maintaining a smooth ripple-free common mode voltage. This controller inherits multifunctional abilities such as harmonics suppression, balancing currents in the grid side network at event of abnormalities in the grid voltages, leakage current elimination, and the reactive power support under grid side voltage sag faults. It thereby complies with the power quality standards IEEE-519 and IEC-61727, as well as the leakage current standards VDE-00126. Extensive simulation and test results are performed to demonstrate the efficacy of the control approach for SECS at various scenarios such as load unbalances abnormalities in the grid voltages, and solar insolation variation in the presence of PV stray capacitance. These results illustrate the superior response of the proposed strategy in comparison conventional controllers. Even under the huge diversions in grid voltage caused at far distant radial ends, the grid currents are observed balanced and sinusoidal, and the leakage currents are significantly suppressed below 300mA. Practically, the solar PV system is connected to the grid and this system is subjected to incessant disturbances, and the presented controller is fine practical solution accounting to its manifold abilities and self-adapting features to the fluctuations in solar panel side as well as the grid side network.

 REFERENCES:

[1] J. Buongiorno, M. Corradini, J. Parsons and D. Petti, “Nuclear energy in a carbon-constrained world: big challenges and big opportunities,” IEEE Power and Energy Magazine, vol. 17, no. 2, pp. 69-77, Apr. 2019.

[2] M. Z. Malik, A. Ali, G. S. Kaloi, A. M. Soomro, M. H. Baloch and S. T. Chauhdary, “Integration of renewable energy project: A technical proposal for rural electrification to local communities,” IEEE Access, vol. 8, pp. 91448-91467, 2020.

[3] S. Vedantham, S. Kumar, B. Singh and S. Mishra, “Fuzzy logic gain-tuned adaptive second-order GI-based multi-objective control for reliable operation of grid-interfaced photovoltaic system,” IET Gen. Tran. Distrib., vol. 12, no. 5, pp. 1153-1163, 2018.

[4] M. A. Awadallah, T. Xu, B. Venkatesh and B. N. Singh, “In the effects of solar panels on distribution transformers,” IEEE Trans. Power Delivery, vol. 31, no. 3, pp. 1176-1185, June 2016.

[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, July 2015.

 

Effect of Various Incremental Conductance MPPT Methods on the Charging of Battery Load Feed by Solar Panel

ABSTRACT:

The presented work in this paper deals with various step sizes used in incremental conductance (INC) related to the maximum power point tracking (MPPT) technique. In the solar photovoltaic system, the variable step size selection method for INC is proposed and compared. The MATLAB/Simulink and hardware setup are used for assessing and analyzing step size methods. The variable step size (DVS), fixed step size (DFS) are comprehensively studied and compared. This DVS method is having a lower ON delay time TdON as 148 msec as regard to 164 msec in the DFS method. On the other hand, the lowest peak-peak oscillations in load current as 0.04 amp for DVS as compared to 0.5A for the DFS method, lower peak current as 1.96A for DVS as compare to 2.37A for the DFS method. In this way, the performance of the DVS method is found superior as it is analyzed and compared with the DFS algorithm.

KEYWORDS:

1.      Renewable energy

2.      Maximum power point tracking

3.      Photovoltaic system

4.       Incremental conductance

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Figure 1. Electrical Equivalent Circuit Of Pv Solar Cell.

 

EXPECTED SIMULATION RESULTS:

 

Figure 2. Load Power For Fix Step Size Inc Algorithm (Simulated Result).

 

Figure 3. Load Power In The Case For Variable Step Size Inc Algorithm (Simulated Result).

 

Figure 4. Load Voltage In The Case For Fix Step Size Inc Algorithm (Simulated Result).

 

Figure 5. Load Voltage In The Case For Variable Step Size Inc Algorithm (Simulated Result).

 

Figure 6. Solar Pv Panel Current In The Case For Fix Step Size Inc Algorithm (Simulated Result).

 

Figure 7. Solar Pv Panel Current In Case Of Variable Step Size Inc Algorithm (Simulated Result).

 

Figure 8. Irradiance Variation In Matlab/Simulation.

 

 CONCLUSION:

This study in this paper reports a comprehensive analysis and comparison between the two-step sizes methods for INC MPPT for solar PV panel. It reflects the superior MPPT tracking system that is built on a variable step size by the DVS method. The delivered power rate of the DVS algorithm is higher when equated with the DFS algorithms. It is quite practicable to deal with the rapid changes in weather conditions due to its stability and low rate of rising time.

As the DVS method, provide the maximum power in comparison to the DFS method. The life of solar panel has been an increase in the case of the DVS method because in the case of the DFS method the operating point is less than the maximum PowerPoint. In this case, the battery withdraws the maximum current from the source to maintain the power. The DFS method is not economical because it provides less power in comparison to the DVS method. So that more solar panel has been required to produce the same power as provided by DVS method.

The load side is not dangerous at higher overshoot current and especially at this point, there is no need for a high-value fuse. The protection circuit is also not necessary which makes it, a cost-effective approach. Salient points of the experimental study are-

·         T_dON  i n the DVS method is gained as 148 msec where 164 msec for the DFS method. _

·         T_P - _PR Peak to peak current oscillations for the DVS method is obtained as 0.04 Amp and 0.5 Amp for Fss.

·         Peak overshoot (M_p) in DVS is 1.96 Amp and 2.37 Amp for DFS.

The load current settles in less time with the sudden change in irradiance in the case of DVS.

 REFERENCES:

[1] M. Akbaba and M. A. A. Alattawi, ``A new model for I_V characteristic of solar cell generators and its applications,'' Sol. Energy Mater. Sol. Cells, vol. 37, no. 2, pp. 123_132, May 1995.

[2] B. C. Babu, T. Cermak, S. Gurjar, Z. M. Leonowicz, and L. Piegari, ``Analysis of mathematical modeling of PV module with MPPT algorithm,'' in Proc. IEEE 15th Int. Conf. Environ. Electr. Eng. (EEEIC), Jun. 2015, pp. 1625_1630.

[3] T. Radjai, L. Rahmani, S. Mekhilef, and J. P. Gaubert, ``Implementation of a modified incremental conductance MPPT algorithm with direct control based on a fuzzy duty cycle change estimator using d-SPACE,'' Sol. Energy, vol. 110, pp. 325_337, Dec. 2014.

[4] A. Gupta,Y. K. Chauhan, and R. K. Pachauri, ``A comparative investigation of maximum power point tracking methods for solar PV system,'' Sol. Energy, vol. 144, pp. 780_797, Oct. 2017.

[5] H. D. Maheshappa, J. Nagaraju, and M. V. K. Murthy, ``An improved maximum power point tracker using a step-up converter with current locked loop,'' Renew. Energy, vol. 13, no. 2, pp. 195_201, Feb. 1998.