Single Phase NPC Inverter Controller with IntegratedMPPT for PV Grid Connection

ABSTRACT:  

This paper presents a single-stage three-level Neutral Point Clamped (NPC) inverter for connection to the electrical power grid, with integrated Maximum Power Point Tracking (MPPT) algorithm to extract the maximum power available from solar photovoltaic (PV) panels. This single-stage topology is more compact than the traditional topology, it was chosen because with the proper control strategy. It is suitable to connect the PV panels to the power grid.

The paper describes the design of a 5 kW NPC inverter for the interface of PV panels with the power grid, presenting the circuit parameters and the description of the control algorithms. A phase locked loop control is used to connect the inverter into the grid. Then, a proposed DC Link voltage control to regulate the input voltage of the inverter. Although an MPPT algorithm was used to optimize the energy extraction and the system efficiency. Inverter Output Current control to produce an output current (current injected in the power grid) with low Total Harmonic Distortion (THD) implemented in a DSP. Simulation and experimental results verify the correct operation of the proposed system, even with fluctuations in the solar radiation.

KEYWORDS:
  1. Photovoltaic System
  2. Maximum Power Point Tracking (MPPT)
  3. Neutral Point Clamped (NPC) Inverter
  4. Phase-Locked Loop (PLL)

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure 1. Block diagram of the NPC converter control system.

EXPECTED SIMULATION RESULTS:

Figure 2. Block diagram of the E-PLL.

Figure 3. Startup of the proposed system with maximum solar radiation: (a)

PV current (ipanels); (b) PV panels voltage (vpanels);

(c) PV panels power (ppanels).

Figure 4. Operation with fluctuations in the solar radiation, from1000 W/m² to

800 W/m² and to 600 W/m: (a) Maximum theoretical power (pmax); (b)

Extracted power PV panels (ppanels); (c) Inverter output current (iout).

Figure 5. Reference current (iref *) and current injected into the power grid (iout).

Figure 6. Power grid voltage (vgrid) and inverter output current (iout).

Figure 7. Voltages in the two capacitors of the DC-link (vc1, vc2).

CONCLUSION:

This paper presents the design, simulation and experimental results of a 5 kW single-stage three-level Neutral Point Clamped (NPC) inverter for connection to the electrical power grid, with integrated Maximum Power Point Tracking (MPPT) algorithm to extract the maximum available power from solar photovoltaic (PV) panels. It also describes the design of the PLL controller, used to track the fundamental power grid voltage in order to synchronize the NPC inverter with the power grid, and to generate a reference for the inverter output current (which consists in the injected power grid current).

All the controllers have been implemented using C code, validated by simulation in PSIM, and executed in a DSP. Experimental results indicate that the current injected in the power grid follows the reference, and that the voltages in the two DC-link capacitors are kept balanced. It is shown that the proposed system is able to always extract the maximum power available from the solar PV panels, even when there are solar radiation fluctuations.

REFERENCES:

[1] S. V. Araújo, S. Member, P. Zacharias, and R. Mallwitz, “Highly Efficient Single-Phase Transformerless Inverters for Grid-Connected Photovoltaic Systems,” Ind. Electron. IEEE Trans., vol. 57, no. 9, pp. 3118–3128, 2010.

[2] S. Saridakis, E. Koutroulis, and F. Blaabjerg, “Optimal  Design of Modern Transformerless PV Inverter Topologies,” Energy Conversion, IEEE Trans., vol. 28, no. 2, pp. 394–404, 2013.

[3] R.Teodorescu, M.Liserre, and P.Rodriguez, Grid Converters for Photovoltaic and Wind Power Systems. 2011.

[4] S. Busquets-monge, J. Rocabert, P. Rodríguez, P. Alepuz, and J. Bordonau, “Multilevel Diode-Clamped Converter for Photovoltaic Generators With Independent Voltage Control of Each Solar Array,” Ind. Electron. IEEE Trans., vol. 55, no. 7, pp. 2713–2723, 2008.

[5] P. Panagis, F. Stergiopoulos, P. Marabeas, and S. Manias, “Comparison of State of the Art Multilevel Inverters,” Power Electron. Spec. Conf. 2008. PESC 2008. IEEE, pp. 4296– 4301, 2008.

PMSG Based Wind Energy Generation System:Energy Maximization and its Control

ABSTRACT:

This paper deals with the energy maximization and control analysis for the permanent magnet synchronous generator (PMSG) based wind energy generation system (WEGS). The system consists of a wind turbine, a three-phase IGBT based rectifier on the generator side and a three-phase IGBT based inverter on the grid side converter system. The pitch angle control by perturbation and observation (P&O) algorithm for obtaining maximum power point tracking (MPPT).

MPPT is most effective under, cold weather, cloudy or hazy days. A designed control technique is proposed for the MPPT mechanism of the system. This paper will explore in detail about the control analysis for both the generator and grid side converter system. Further, it will also discuss about the pitch angle control for the wind turbine in order to obtain maximum power for the complete wind energy generation system. The proposed WEGS for maximization of power is modelled, designed and simulated using MATLAB R2014b Simulink with its power system toolbox and discrete step solver incorporated in the simulation tool.

KEYWORDS:

  1. Maximum power point tracking (MPPT)
  2. Permanent magnet synchronous generator (PMSG)
  3. Pitch angle control (PAC)
  4. Wind energy generation system (WEG)

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Control issue in PMSG based wind turbine system

EXPECTED SIMULATION RESULTS:

 

Fig.2. Wind speed (15 m/s).

Fig.3. Pitch angle ( 26 Degree).

Fig.4. Active power output (1.49 MW).

Fig.5. Stator voltage of PMSG (per unit).

Fig.6. Stator current of PMSG (per unit).

Fig.7. Wind speed (m/s).

Fig.8. Pitch control.

Fig.9. Electrical torque of PMSG.

Fig.10. Wind turbine power with pitch control.

 CONCLUSION:

This paper has briefly discussed about the energy maximization and control analysis for the PMSG based wind energy generation system. The paper also explored in detail about the different control algorithm for both the machine and grid side converter system and has used VSC control for our proposed mechanism. A brief discussion on the pitch angle control for the wind turbine has been described which aims to obtain maximum power for the complete wind energy generation system.

A designed control technique named as (P&O) has also been proposed for the MPPT mechanism of the system whose results has been validated using MATLAB R2014b Simulink. As discussed before the presented technique includes maximum power point tracking module, pitch angle control and average model for machine side and grid side converters. Also, the integrated control system controls the generator speed, DC-link voltage and active power along with the above-mentioned factors.

REFERENCES:

[1] M. Benadja and A. Chandra, “A new MPPT algorithm for PMSG based grid connected wind energy system with power quality improvement features”, IEEE Fifth Power India Conference, Murthal, pp. 1-6, 2012.

[2] S. Sharma and B. Singh, “An autonomous wind energy conversion system with permanent magnet synchronous generator”, International Conference on Energy, Automation and Signal, Bhubaneswar, Odisha, pp. 1-6, 2011.

[3] M. Singh and A. Chandra, “Power maximization and voltage sag/swell ride-through capability of PMSG based variable speed wind energy conversion system”,34th Annual Conference of IEEE Industrial Electronics, Orlando, FL, pp. 2206-2211, 2008.

[4] T. Tafticht, K. Agbossou, A. Cheriti and M. L. Doumbia, “Output Power Maximization of a Permanent Magnet Synchronous Generator Based Stand-alone Wind Turbine”,IEEE International Symposium on Industrial Electronics, Montreal, pp. 2412-2416, 2006.

[5] N. A. Orlando, M. Liserre, R. A. Mastromauro and A. D. Aquila, “A Survey of Control Issues in PMSG-Based Small Wind-Turbine Systems”, IEEE Transactions on Industrial Informatics, vol. 9, no. 3, pp. 1211-1221, Aug. 2013.

Induction Motor Drive For PV Water PumpingWith Reduced Sensors

ABSTRACT:

 This study presents the reduced sensors based standalone solar photovoltaic (PV) energised water pumping. The system is configured to reduce both cost and complexity with simultaneous assurance of optimum power utilisation of PV array. The proposed system consists of an induction motor-operated water pump, controlled by modified direct torque control. The PV array is connected to the DC link through a DC–DC boost converter to provide maximum power point tracking (MPPT) control and DC-link voltage is maintained by a three-phase voltage-source inverter. The estimation of motor speed eliminates the use of tacho generator/encoder and makes the system cheaper and robust. Moreover, an attempt is made to reduce the number of current sensors and voltage sensors in the system. The proposed system constitutes only one current sensor and only one voltage sensor used for MPPT as well as for the phase voltage estimation and for the phase currents’ reconstruction. Parameters adaptation makes the system stable and insensitive toward parameters variation. Both simulation and experimental results on the developed prototype in the laboratory validate the suitability of proposed system.

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1 circuit diagram (a) Proposed system,

EXPECTED SIMULATION RESULTS:

Fig. 2 Performance indices (a) PV array during starting to steady state at 1000 W/m2, (b) IMD indices at 1000 W/m2

 Fig. 3 Performance indices during insolation change 1000–500 W/m2

(a) PV array, (b) IMD indices 500–1000 W/m2, (c) PV array (d) IMD indices

Fig. 4 Adaptation mechanism

(a) Rs adaptation at rated speed and insolation, (b) τr Adaptation at rated speed and rated insolation

Fig. 5 Performance indices of the drive

(a) Starting at 1000 W/m2, (b) Starting at 500 W/m2, (c) Steady state at 1000 W/m2,

(d) Steady state at 500 W/m2

Fig. 6 Dynamic performance of the drive under variable insolation

(a) 1000–500 W/m2, (b) 500–1000 W/m2, (c) Intermediate speed signals at 1000–500

W/m2, (d) Intermediate speed signals at 500–1000 W/m2

Fig. 7 Intermediate signals in terms of

(a) Te* and Te at 1000–500 W/m2, (b) 500–1000 W/m2, (c) Reference stationary

components of flux and estimated flux at 1000–500 W/m2, (d) 500–1000 W/m2

Fig. 8 Reconstructed and measured current waveforms of phases a and b

at (a) Starting performance at 1000 W/m2, (b) 1000 W/m2, (c) 500 W/m2, (d) Boost

converter parameters at 1000 W/m2

CONCLUSION:

The modelling and simulation of the proposed system has been carried out in MATLAB/Simulink and its suitability is validated experimentally on a developed prototype in the laboratory. The system comprises of one voltage sensor and one current sensor, which are sufficient for the proper operation of the proposed system. The motor-drive system performs satisfactorily during starting at various insolations, steady-state, dynamic conditions represented by changing insolation. The speed estimation has been carried out by flux components in stationary frame of reference. The flux and torque are controlled separately. Therefore, successful observation of the proposed system with satisfactory performance has been achieved without the mechanical sensors. This topology improves the stability of the system. The stability of the system at rated condition toward stator resistance variation is shown by Nyquist stability curve and the stability toward the rotor-time constant perturbation is shown by Popov’s criteria. The DTC of an induction motor with fixed frequency switching technique reduces the torque ripple. The line voltages are estimated from this DC-link voltage. Moreover, the reconstruction of three-phase stator currents has been successfully carried out from DC-link current. Simulation results are well validated by test results. Owing to the virtues of simple structure, control, cost-effectiveness, fairly good efficiency and compactness, it is inferred that the suitability of the system can be judged by deploying it in the field.

REFERENCES:

[1] Masters, G.M.: ‘Renewable and efficient electric power systems’ (IEEE Press,Wiley and Sons, Inc., Hoboken, New Jersey, 2013), pp. 445–452

[2] Foster, R., Ghassemi, M., Cota, M.: ‘Solar energy: renewable energy and the environment’ (CRC Press, Taylor and Francis Group, Inc., Boca Raton, Florida, 2010)

[3] Parvathy, S., Vivek, A.: ‘A photovoltaic water pumping system with high efficiency and high lifetime’. Int. Conf. Advancements in Power and Energy (TAP Energy), Kollam, India, 24–26 June 2015, pp. 489–493

[4] Shafiullah, G.M., Amanullah, M.T., Shawkat Ali, A.B.M., et al.: ‘Smart grids: opportunities, developments and trends’ (Springer, London, UK, 2013)

[5] Sontake, V.C., Kalamkar, V.R.: ‘Solar photovoltaic water pumping system – a comprehensive review’, Renew. Sustain. Energy Rev., 2016, 59, pp. 1038– 1067

Control of a Three-Phase Hybrid Converter for a PV Charging Station

ABSTRACT:  

Hybrid Boost converter (H BC) has been proposed to supplant a dc/dc support converter and a dc/air conditioning converter to decrease transformation stages and exchanging misfortune. In this paper, control of a three-stage H BC in a P V charging station is structured and tried. This H BC interfaces a P V framework, a dc framework with a hybrid plugin electrical vehicles (HP E V s) and a three-stage air conditioning network. The control of the H BC is intended to acknowledge most maximum power point tracking (MP PT) for P V, dc transport voltage direction, and air conditioning voltage or receptive power control. A proving ground with power hardware exchanging subtleties is worked in MAT LAB/Sim Power systems for approval. Reproduction results show the possibility of the structured control design. At last, lab exploratory testing is directed to show H BC’s control execution.

 BLOCK DIAGRAM:

Fig. 1. Topology of the three-phase H BC-based P V charging station.

EXPECTED SIMULATION RESULTS:

 

 Fig. 2. Performance of a modified I C-PI MP PT algorithm when solar

irradiance variation is applied.

Fig. 3. Performance of the dc voltage control in the vector control. The solid lines represent the system responses when the dc voltage control is enabled. The dashed lines represent the system responses when the dc voltage control is disabled.

Fig. 4. Performance of a proposed vector control to supply or absorb reactive power independently.

Fig. 5. Power management of P V charging station.

Fig. 6. D st, Md and M q for case 4.

Fig. 7. System performance under 70% grid’s voltage drop.

 CONCLUSION:

Control of three-stage H BC in a P  V charging station is proposed in this paper. The three-stage H BC can spare exchanging misfortune by joining a dc/dc sponsor and a dc/air conditioning converter into a solitary converter structure. Another control for the three-stage H BC is intended to accomplish MP PT, dc voltage direction and responsive power following. The MPPT control uses altered gradual conductance-PI based MPPT strategy. The dc voltage direction and responsive power following are acknowledged utilizing vector control.

Five contextual investigations are led in PC reenactment to exhibit the execution of MPPT, dc voltage controller, responsive power following and in general power the board of the PV charging station. Trial results check the task of the PHEV charging station utilizing HBC topology. The reproduction and trial results show the adequacy and vigor of the proposed control for PV charging station to keep up nonstop dc control supply utilizing both PV power and air conditioning framework control.

REFERENCES

[1]A. Khaligh and S. Dusmez, “Comprehensive topological analysis of conductive
and inductive charging solutions for plug-in electric vehicles,”
IEEE Transactions on Vehicular Technology, vol. 61, no. 8, pp. 3475–
3489, 2012.
[2] T. Anegawa, “Development of quick charging system for electric vehicle,”
Tokyo Electric Power Company, 2010.
[3] F. Musavi, M. Edington, W. Eberle, and W. G. Dunford, “Evaluation
and efficiency comparison of front end ac-dc plug-in hybrid charger
topologies,” IEEE Transactions on Smart grid, vol. 3, no. 1, pp. 413–
421, 2012.
[4] M. Yilmaz and P. T. Krein, “Review of battery charger topologies,
charging power levels, and infrastructure for plug-in electric and hybrid
vehicles,” IEEE Transactions on Power Electronics, vol. 28, no. 5, pp.
2151–2169, May 2013.
[5] G. Gamboa, C. Hamilton, R. Kerley, S. Elmes, A. Arias, J. Shen, and
I. Batarseh, “Control strategy of a multi-port, grid connected, direct-dc
pv charging station for plug-in electric vehicles,” in Energy Conversion
Congress and Exposition (ECCE), 2010 IEEE. IEEE, 2010, pp. 1173–
1177.

Control of Solar Photovoltaic Integrated Universal Active Filter Based on Discrete Adaptive Filter

ABSTRACT:

In this work, a novel technique based on adaptive filtering is proposed for the control of three-phase universal active power filter with a solar photovoltaic array integrated at its DC bus. Two adaptive filters along with a zero crossing detection technique are used to extract the magnitude of fundamental active component of distorted load currents, which is then used in estimation of reference signal for the shunt active filter. This technique enables extraction of active component of all three phases with reduced mathematical computation. The series active filter control is based on synchronous reference frame theory and it regulates load voltage and maintains it in-phase with voltage at point of common coupling under conditions of voltage sag and swell. The performance of the system is evaluated on an experimental prototype in the laboratory under various dynamic conditions such as sag and swells in voltage at point of common coupling, load unbalancing and change in solar irradiation intensity.

 

KEYWORDS:

  1. Power quality
  2. Universal active power filter
  3. Adaptive filtering
  4. Photovoltaic system
  5. Maximum power point tracking
  6. Quadrature signal generation

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig.1 System Configuration of Solar Photovoltaic Integrated Unified Active Power Filter 

  

EXPECTED SIMULATION RESULTS

 

Fig.2 Salient Signals in Series Active Filter Control

Fig.3. Salient Signals in Extraction of Fundamental Positive Sequence Load Current using Adaptive Filter

Fig. 4. Steady State Per Phase Signals of PCC and Load Side in a PV-UAPF Compensated System

Fig. 5. Performance of PV-UAPF Under Three Phase Short Circuit Fault

CONCLUSION:

The performance of adaptive filter based PV-UAPF system under both steady state and dynamic conditions have been analyzed in detail. The method of sampling the fundamental component of load current obtained through adaptive filter enables fast extraction of fundamental active component of nonlinear load currents for all phases in one sampling. Only two adaptive filters are required to extract magnitude of active component of three phase load currents. This technique requires reduced computational resources while achieving good dynamic and steady state performance in extraction of fundamental active component of nonlinear load current. The system performance has been found to be satisfactory under various disturbances in load current, PCC voltage and solar irradiation. The series active filter is able to regulate load voltage at 220 V under variations of PCC voltage from 170 V to 270 V. The grid   current THD is maintained at approximately 3% even though the THD of load current is 28% thus meeting requirement of IEEE-519 standard. The PV-UAPF system has been able to maintain the grid currents balanced under unbalanced loading condition. The proposed topology and algorithm are suited for employing in conditions where PCC voltage sags/swells and load current harmonics are major power quality issues. Certain power quality issues not addressed include voltage distortions, flicker, neutral current compensation etc. This power quality issues can be addressed by modification of topology and control algorithm according to the requirements in the distribution system. The PV-UAPF system provides dual benefit of distributed generation as well as improving power quality of the distribution system.

 

REFERENCES:

  • R. Tummuru,M. K. Mishra, and S. Srinivas, “Dynamic energy management of hybrid energy storage system with high-gain pv converter,” IEEE Transactions on Energy Conversion, vol. 30, no. 1, pp. 150–160, March 2015.
  • Singh, A. Chandra, K. A. Haddad, Power Quality: Problems and Mitigation Techniques. London: Wiley, 2015.
  • Devassy and B. Singh, “Control of solar photovoltaic integrated upqc operating in polluted utility conditions,” IET Power Electronics, vol. 10, no. 12, pp. 1413–1421, Oct 2017.
  • Devassy and B. Singh, “Performance analysis of proportional resonant and adaline-based solar photovoltaic-integrated unified active power filter,” IET Renewable Power Generation, vol. 11, no. 11, pp. 1382–1391, 2017.
  • Ramya and J. Pratheebha, “A novel control technique of solar farm inverter as pv-upfc for the enhancement of transient stability in power grid,” in 2016 International Conference on Emerging Trends in Engineering, Technology and Science (ICETETS), Feb 2016, pp. 1–7.

Design and Implementation of a Novel Multilevel DC–AC Inverter

ABSTRACT:

In this paper, a novel multilevel dc–ac inverter is proposed. The proposed multilevel inverter generates seven-level ac output voltage with the appropriate gate signals’ design. Also, the low-pass filter is used to reduce the total harmonic distortion of the sinusoidal output voltage. The switching losses and the voltage stress of power devices can be reduced in the proposed multilevel inverter. The operating principles of the proposed inverter and the voltage balancing method of input capacitors are discussed. Finally, a laboratory prototype multilevel inverter with 400-V input voltage and output 220 Vrms/2 kW is implemented. The multilevel inverter is controlled with sinusoidal pulse-width modulation (SPWM) by TMS320LF2407 digital signal processor (DSP). Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.

KEYWORDS:

  1. DC–AC inverter
  2. Digital signal processor (DSP)
  3. Maximum power point tracking (MPPT)
  4. Multilevel

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of renewable system

EXPECTED SIMULATION RESULTS:

 Fig. 2. Waveforms of vgs1, vab, vo, and io at 500 W.

Fig. 3. Output voltage harmonic spectrum of vab calculated by FFT.

Fig. 4. Output voltage harmonic spectrum of vo calculated by FFT

Fig. 5. Waveforms of vC2, vo, and io at 1000 W.

Fig. 6. Waveforms of vC2, vo, and io at 2000 W.

Fig. 7. Waveforms of vo and io at 400 VA.

 CONCLUSION:

A novel seven-level inverter was designed and implemented with DSP in this paper. The main idea of the proposed configuration is to reduce the number of power device. The reduction of power device is proved by comparing with traditional structures. Finally, a laboratory prototype of seven-level inverter with 400-V input voltage and output 220 Vrms/2kW is implemented. Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.

 REFERENCES:

[1] R. Gonzalez, E. Gubia, J. Lopez, and L. Marroyo, “Transformerless single-phase multilevel-based photovoltaic inverter,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2694–2702, Jul. 2008.

[2] S. Daher, J. Schmid, and F. L.M. Antunes, “Multilevel inverter topologies for stand-alone PV systems,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2703–2712, Jul. 2008.

[3] W. Yu, J. S. Lai, H. Qian, and C. Hutchens, “High-efficiency MOSFET inverter with H6-type configuration for photovoltaic nonisolated, acmodule applications,” IEEE Trans. Power Electron., vol. 26, no. 4, pp. 1253–1260, Apr. 2011.

[4] R. A. Ahmed, S. Mekhilef, and W. P. Hew, “New multilevel inverter topology with minimum number of switches,” in Proc. IEEE Region 10 Conf. (TENCON), 2010, pp. 1862–1867.

[5] M. R. Banaei and E. Salary, “New multilevel inverter with reduction of switches and gate driver,” in Proc. IEEE 18th Iran. Conf. Elect. Eng. (IECC), 2010, pp. 784–789.

BLDC Motor Driven Solar PV Array Fed Water Pumping System Employing Zeta Converter

BLDC Motor Driven Solar PV Array Fed Water Pumping System Employing Zeta Converter

 ABSTRACT:

This paper proposes a simple, cost effective and efficient brushless DC (BLDC) motor drive for solar photovoltaic (SPV) array fed water pumping system. A zeta converter is utilized in order to extract the maximum available power from the SPV array. The proposed control algorithm eliminates phase current sensors and adapts a fundamental frequency switching of the voltage source inverter (VSI), thus avoiding the power losses due to high frequency switching. No additional control or circuitry is used for speed control of the BLDC motor. The speed is controlled through a variable DC link voltage of VSI. An appropriate control of zeta converter through the incremental conductance maximum power point tracking (INC-MPPT) algorithm offers soft starting of the BLDC motor. The proposed water pumping system is designed and modeled such that the performance is not affected under dynamic conditions. The suitability of proposed system at practical operating conditions is demonstrated through simulation results using MATLAB/ Simulink followed by an experimental validation.

KEYWORDS:

  1. BLDC motor
  2. SPV array
  3. Water pump
  4. Zeta converter
  5. VSI
  6. INC-MPPT

 

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Configuration of proposed SPV array-Zeta converter fed BLDC motor drive for water pumping system

EXPECTED SIMULATION RESULTS:

Fig.2 Performances of the proposed SPV array based Zeta converter fed BLDC motor drive for water pumping

system (a) SPV array variables, (b) Zeta converter variables, and (c) BLDC motor-pump variables.

 

CONCLUSION:

The SPV array-zeta converter fed VSI-BLDC motor-pump for water pumping has been proposed and its suitability has been demonstrated by simulated results using MATLAB/Simulink and its sim-power-system toolbox. First, the proposed system has been designed logically to fulfil the various desired objectives and then modelled and simulated to examine the various performances under starting, dynamic and steady state conditions. The performance evaluation has justified the combination of zeta converter and BLDC motor drive for SPV array based water pumping. The system under study availed the various desired functions such as MPP extraction of the SPV array, soft starting of the BLDC motor, fundamental frequency switching of the VSI resulting in a reduced switching losses, reduced stress on IGBT switch and the components of zeta converter by operating it in continuous conduction mode and stable operation. Moreover, the proposed system has operated successfully even under the minimum solar irradiance.

REFERENCES:

  • Uno and A. Kukita, “Single-Switch Voltage Equalizer Using Multi- Stacked Buck-Boost Converters for Partially-Shaded Photovoltaic Modules,” IEEE Transactions on Power Electronics, no. 99, 2014.
  • Arulmurugan and N. Suthanthiravanitha, “Model and Design of A Fuzzy-Based Hopfield NN Tracking Controller for Standalone PV Applications,” Electr. Power Syst. Res. (2014). Available: http://dx.doi.org/10.1016/j.epsr.2014.05.007
  • Satapathy, K.M. Dash and B.C. Babu, “Variable Step Size MPPT Algorithm for Photo Voltaic Array Using Zeta Converter – A Comparative Analysis,” Students Conference on Engineering and Systems (SCES), pp.1-6, 12-14 April 2013.
  • Trejos, C.A. Ramos-Paja and S. Serna, “Compensation of DC-Link Voltage Oscillations in Grid-Connected PV Systems Based on High Order DC/DC Converters,” IEEE International Symposium on Alternative Energies and Energy Quality (SIFAE), pp.1-6, 25-26 Oct. 2012.
  • K. Dubey, Fundamentals of Electrical Drives, 2nd ed. New Delhi, India: Narosa Publishing House Pvt. Ltd., 2009.

Design and Implementation of a Novel Multilevel DC–AC Inverter

 

ABSTRACT:

In this paper, a novel multilevel dc–ac inverter is proposed. The proposed multilevel inverter generates seven-level ac output voltage with the appropriate gate signals’ design. Also, the low-pass filter is used to reduce the total harmonic distortion of the sinusoidal output voltage. The switching losses and the voltage stress of power devices can be reduced in the proposed multilevel inverter. The operating principles of the proposed inverter and the voltage balancing method of input capacitors are discussed. Finally, a laboratory prototype multilevel inverter with 400-V input voltage and output 220 Vrms/2 kW is implemented. The multilevel inverter is controlled with sinusoidal pulse-width modulation (SPWM) by TMS320LF2407 digital signal processor (DSP). Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.

KEYWORDS:

  1. DC–AC inverter
  2. Digital signal processor (DSP)
  3. Maximum power point tracking (MPPT)
  4. Multilevel

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of renewable system.

EXPECTED SIMULATION RESULTS:

Fig. 2. Waveforms of vgs1, vab, vo, and io at 500 W.

Fig. 3. Output voltage harmonic spectrum of vab calculated by FFT.

Fig. 4. Output voltage harmonic spectrum of vo calculated by FFT

Fig. 5. Waveforms of vC2, vo, and io at 1000 W.

Fig. 6. Waveforms of vC2, vo, and io at 2000 W.

Fig. 7. Waveforms of vo and io at 400 VA.

 

CONCLUSION:

A novel seven-level inverter was designed and implemented with DSP in this paper. The main idea of the proposed configuration is to reduce the number of power device. The reduction of power device is proved by comparing with traditional structures. Finally, a laboratory prototype of seven-level inverter with 400-V input voltage and output 220 Vrms/2kW is implemented. Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.

REFERENCES:

[1] R. Gonzalez, E. Gubia, J. Lopez, and L. Marroyo, “Transformerless single-phase multilevel-based photovoltaic inverter,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2694–2702, Jul. 2008.

[2] S. Daher, J. Schmid, and F. L.M. Antunes, “Multilevel inverter topologies for stand-alone PV systems,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2703–2712, Jul. 2008.

[3] W. Yu, J. S. Lai, H. Qian, and C. Hutchens, “High-efficiency MOSFET inverter with H6-type configuration for photovoltaic nonisolated, acmodule applications,” IEEE Trans. Power Electron., vol. 26, no. 4, pp. 1253–1260, Apr. 2011.

[4] R. A. Ahmed, S. Mekhilef, and W. P. Hew, “New multilevel inverter topology with minimum number of switches,” in Proc. IEEE Region 10 Conf. (TENCON), 2010, pp. 1862–1867.

[5] M. R. Banaei and E. Salary, “New multilevel inverter with reduction of switches and gate driver,” in Proc. IEEE 18th Iran. Conf. Elect. Eng. (IECC), 2010, pp. 784–789.

Design of a multilevel inverter with reactive power Control ability for connecting PV cells to the grid

 

ABSTRACT:  

With the increasing use of PV cells in power system, optimal utilization of the equipment is an important issue. In these systems the MPPT controller is used to inject the maximum available power from solar energy. During day time that the active power decreases because of low intensity, the inverter is capable of injecting reactive power up to its nominal capacity and this is a chance for reactive power compensation. In this paper the aim is to propose a control method for injecting the maximum active power and if possible, the reactive power. In addition, a low pass filter is suggested to solve the problem of current fluctuations in case of unbalanced load. Simulation results on a typical system in MATLAB indicate proper performance of the presented method.

KEYWORDS:

 NPC inverter

Maximum Power Point Tracking (MPPT)

Photovoltaic cell (PV)

PI current control

Space vector pulse width modulation (SVPWM)

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 image001

Fig1. Studied system for injecting power to the grid and local load

EXPECTED SIMULATION RESULTS:
image002

Figure2. output active and reactive power of the inverter

image003

Figure3. THD of injected current to the grid in no-load condition

image004

Figure4. Injecting active power in no-load condition and low intensity of light

image005

Figure5. load increase at t=0.5s and its effects on active and reactive power

image006

Figure6. Injected voltage and current to the grid and the effect of inductive load on current

image007

Figure7. Analyzing THD of injected current to the grid in PeL=50kw and PQL=30kvar condition

image008

Figure8. Power increment in two levels: a. at t=0.5s and b. at t=0.7s

image009

Figure9. Output power of inverter and the grid

image010

Figure10. Output voltage and current after using filter and limiter

image011

Figure11. THD of circuit when PeL=50kw and PQL=30kvar and using filter and limiter

CONCLUSION:

In this paper a control strategy is proposed for current control of PV inverter that control s maximum generated active power and reactive power compensation of local load simultaneously .The main idea is to utilize inverter for reactive power injection during active power decrement .using a low pass filter and power limiter in control system , produced oscillations due to unbalanced load is eliminated and inverter works in safe condition simulation results show the proposed method to be viable in controlling inverter

REFERENCES:

[1] Chung-ChuanHou,Chih-Chung Shih, Po-Tai Cheng,Ahmet M. Hava, Common-Mode Voltage Reduction Pulsewidth

Modulation Techniques for Three-Phase Grid-Connected Converters , IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 28, NO. 4, APRIL 2013

[2] GeorgiosTsengenes, Thomas Nathenas, Georgios Adamidis,” A three-level space vector modulated grid connected inverter with control scheme based on instantaneous power theory”, Simulation Modelling Practice and Theory 25 (2012) 134–147

[3] S. Kouro, K. Asfaw, R. Goldman, R. Snow, B. Wu, and J. Rodríguez, NPC Multilevel Multistring Topology for Larg Scale Grid Connected Photovoltaic Systems,2010 2nd IEEE International Symposium on Power Electronics for Distributed Generation Systems

[4] Georgios A. Tsengenes, Georgios A. Adamidis, Study of a Simple Control Strategy for Grid

Connected VSI Using SVPWM and p-q Theory,XIX International Conference on Electrical Machines – ICEM 2010, Rome

[5] César Trujillo Rodríguez, David Velasco de la Fuente, Gabriel Garcerá, Emilio Figueres, and Javier A. Gua can eme Moreno,Reconfigurable Control Scheme for a PV

2016-17 IEEE Electrical Projects List

Model Predictive Control of PV Sources in A Smart DC Distribution System Maximum Power Point Tracking and Droop Control

 

ABSTRACT:

In a dc distribution system, where multiple power sources supply a common bus, current sharing is an important issue. When renewable energy resources are considered, such as photovoltaic (PV), dc/dc converters are needed to decouple the source voltage, which can vary due to operating conditions and maximum power point tracking (MPPT), from the dc bus voltage. Since different sources may have different power delivery capacities that may vary with time, coordination of the interface to the bus is of paramount importance to ensure reliable system operation. Further, since these sources are most likely distributed throughout\ the system, distributed controls are needed to ensure a robust and fault tolerant control system. This paper presents a model predictive control-based MPPT and model predictive control-based droop current regulator to interface PV in smart dc distribution systems. Back-to-back dc/dc converters control both the input current from the PV module and the droop characteristic of the output current injected into the distribution bus. The predictive controller speeds up both of the control loops, since it predicts and corrects error before the switching signal is applied to the respective converter.

KEYWORDS:

  1. DC microgrid
  2. Droop control
  3. Maximum power point tracking (MPPT)
  4. Model predictive control (MPC)
  5. Photovoltaic (PV)
  6. Photovoltaic systems

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

image001

Fig. 1. Multiple-sourced dc distribution system with central storage.

EXPECTED SIMULATION RESULTS:

image002

Fig. 2. Ideal bus voltage and load power as system impedance increases and loads are interrupted to prevent voltage collapse. (a) Bus voltage decreases in response to increased system impedance at t1 to reach the operating point on the new P–V curve at t2 . The new bus voltage is below the UVP limit, so control action cause load to be shed, moving to a new operating point on the same P–V curve at t3 with a higher bus voltage. (b) Load power in the system changes as point-of-load converters are turned OFF to reduce total system load when the bus voltage drops below the UVP.

image003

Fig. 3. Response of dc bus voltage to step changes in the power drained by load.

image004

Fig. 4. Response of dc bus voltage and output power to imbalanced input PV sources

image005

Fig. 5. Response validation of dc bus voltage to step changes in the power drained by load.

image006

Fig. 6. Response validation of dc bus voltage and output power to imbalanced input PV sources.

image007

Fig. 7. Response of dc bus voltage and output power to the input PV sources of Fig. 7.

CONCLUSION:

 High efficiency and easy interconnection of renewable energy sources increase interests in dc distribution systems. This paper examined autonomous local controllers in a single-bus dc microgrid system for MPP tracked PV sources. An improved MPPT technique for dc distribution system is introduced by predicting the error at next sampling time using MPC. The proposed predictive MPPT technique is compared to commonly used P&O method to show the benefits and improvements in the speed and efficiency of the MPPT. The results show that the MPP is tracked much faster by using the MPC technique than P&O method.

In a smart dc distribution system for microgrid community, parallel dc/dc converters are used to interconnect the sources, load, and storage systems. Equal current sharing between the parallel dc/dc converters and low voltage regulation is required. The proposed droop MPC can achieve these two objectives. The proposed droop control improved the efficiency of the dc distribution system because of the nature of MPC, which predicts the error one step in horizon before applying the switching signal. The effectiveness of the proposed MPPT-MPC and droop MPC is verified through detailed simulation of case studies. Implementation of the MPPT-MPC and droop MPC using dSPACE DS1103 validates the simulation results.

REFERENCES:

[1] Z. Peng, W. Yang, X. Weidong, and L. Wenyuan, “Reliability evaluation of grid-connected photovoltaic power systems,” IEEE Trans. Sustain. Energy, vol. 3, no. 3, pp. 379–389, Jun. 2012.

[2] W. Baochao, M. Sechilariu, and F. Locment, “Intelligent DC microgrid with smart grid communications: Control strategy consideration and design,” IEEE Trans. Smart Grid, vol. 3, no. 4, pp. 2148–2156, Dec. 2012.

[3] R. Majumder, “A hybrid microgrid with DC connection at back to back converters,” IEEE Trans. Smart Grid, vol. 5, no. 1, pp. 251–259, Jun. 2013.

[4] R. Lasseter, A. Akhil, C. Marnay, J. Stephens, J. Dagle, R. Guttromson, A. S. Meliopoulous , R. Yinger, and J. Eto, “Integration of distributed energy resources. The CERTS microgrid concept,” U.S. Dept. Energy, Tech. Rep. LBNL-50829, 2002.

[5] T. Esram and P. L.Chapman, “Comparison of photovoltaic array maximum power point tracking techniques,” IEEE Trans. Energy Convers., vol. 22, no. 2, pp. 439–449, Jun. 2007.