Integration of PV, Battery and Super capacitor in Islanded Microgrid

 ABSTRACT:

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

 KEYWORDS:

1.      Battery

2.      MPPT Controller

3.      Photo Voltaic Cell

4.      Super capacitor

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1. Hybrid system model of PV, Battery and Super capacitor

EXPECTED SIMULATION RESULTS:

Fig.2. DC Bus voltages across two terminals using conventional controller

Fig.3. DC Bus voltages across two terminals using proposed controller

Fig.4. Power consumed by the load using conventional controller

Fig.5. Power consumed by the load using proposed controller

Fig.6. Power sharing between different sources using conventional Controller

Fig.7. Power sharing between different sources using proposed controller

Fig.8. SOC of Battery

Fig.9. Battery Voltage

Fig.10. Battery Current

Fig.11. SOC of Super capacitor

Fig.12. Voltage of Super capacitor

Fig.13. Current of Super capacitor

 

 CONCLUSION:

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

REFERENCES:

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

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

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

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

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

Induction motor drive for PV water pumping with 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

 BLOCK DIAGRAM:

Fig. 1 Block diagram

(a)     Conventional system, (b) Proposed system, (c) Scheme of the 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

 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

Improved MPPT method to increase accuracy and speed in photovoltaic systems under variable atmospheric conditions

 ABSTRACT:

The changes in temperature and radiation cause visible fluctuations in the output power produced by the photovoltaic (PV) panels. It is essential to keep the output voltage of the PV panel at the maximum power point (MPP) under varying temperature and radiation conditions. In this study, a maximum power point tracking (MPPT) method has been developed which is based on mainly two parts: the first part is adapting calculation block for the reference voltage point of MPPT and the second one is Fuzzy Logic Controller (FLC) block to adjust the duty cycle of PWM applied switch (MOSFET) of the DC-DC converter. In order to evaluate the robustness of the proposed method, Matlab/Simulink program has been used to compare with the traditional methods which are Perturb & Observe (P&O), Incremental Conductance (Inc. Cond.) and FLC methods under variable atmospheric conditions. When the test results are observed, it is clearly obtained that the proposed MPPT method provides an increase in the tracking capability of MPP and at the same time reduced steady state oscillations. The accuracy of the proposed method is between 99.5% and 99.9%. In addition, the time to capture MPP is 0.021 sec. It is about four times faster than P&O and five times faster than for Inc. Cond. and, furthermore, the proposed method has been compared with the conventional FLC method and it has been observed that the proposed method is faster about 28% and also its efficiency is about 1% better than FLC method.

KEYWORDS:

1.      PV

2.      MPPT methods

3.      FLC based MPPT

4.      DC-DC converter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of the designed system.

 EXPECTED SIMULATION RESULTS:

  

Fig. 2. PV currents for proposed MPPT technique.

 

  

Fig. 3. PV voltages for proposed MPPT technique under variable irradiance (fixed temperature).

  

Fig. 4. PV power for four different MPPT techniques under variable temperature (fixed irradiance).

 

 

   

Fig. 5. PV currents for proposed MPPT technique.

  

Fig. 6. PV voltages for proposed MPPT technique under variable temperature (fixed irradiance).

Fig. 7. (a) P-V characteristics curve, (b) Tracking global peak point for proposed MPPT technique.

CONCLUSION:

 

This study proposes a novel MPPT method and the detailed performance comparison with commonly used methods such as P&O, Incremental conductance and FLC techniques is achieved. Under sudden change in atmospheric operating conditions, the proposed MPPT method performs better performance than other methods to determine MPP. The efficiency of proposed MPPT method is between 99.5% and 99.9%, while P&O is between 91% and 98%, Inc. Cond. Is between 96% and 99% and FLC is between 98.8% and 99.4% for all case studies. The proposed MPPT method has achieved the lowest oscillation rate at the MPP compared to commonly used methods. This brings the method to the forefront in terms of efficiency. The duration of the proposed MPPT technique to reach a steady state has been measured as 0.021 sec. It is about four times faster than P&O and five times faster than for Inc. Cond. and, furthermore, the proposed method has been compared with the conventional FLC method and it has been observed that the proposed method is faster about 28% than FLC method this means the speed of proposed MPPT technique is the best. At the same time, the amount of oscillation is very low compared to conventional methods. The accuracy of the algorithm is high (%99.9 in many study cases) and also the proposed method is easy to implement in the system.

REFERENCES:

[1] Luo HY, Wen HQ, Li XS, Jiang L, Hu YH. Synchronous buck converter based lowcost and high-efficiency sub-module DMPPT PV system under partial shading conditions. Energy Convers Manage 2016;126:473–87.

[2] Babaa SE, Armstrong M, Pickert V. Overview of maximum power point tracking control methods for PV systems. J Power Energy Eng 2014;2:59–72.

[3] Dolara AFR, Leva S. Energy comparison of seven MPPT techniques for PV systems. J Electromagn Anal Appl 2009;3:152–62.

[4] Ngan MS, Tan CW. A study of maximum power point tracking algorithms for standalone photovoltaic systems. Applied Power Electronics Colloquium (IAPEC): IEEE. 2011. p. 22–7.

[5] Liu JZ, Meng HM, Hu Y, Lin ZW, Wang W. A novel MPPT method for enhancing energy conversion efficiency taking power smoothing into account. Energy Convers Manage 2015;101:738–48.