Simulation of DC/DC Converter for DC Nano-Grid Integrated with Solar PV Generation

Rajesh M Pindoriya

Co-Authors,

S RajendranIndian Institute of Technology

Gandhinagar (IITGn)

Dr. N M PindoriyaIndian Institute of Technology

Gandhinagar (IITGn)

Aim of a paper

Introduction of Nano grid

The need of Nano grid

Environmental aspects

Schematic layout of DC Nano grid integrated with solar PV generation

Simulink Model of DC Nano grid

Future directions on Nano grid research

Conclusion

References

Outline

Distributed energy resources (DER) based micro grid and Nano-grid framework is most technically viable bottom-top approach to sustainably meet ever-increasing demand of rural and urban communities.

This paper presents simulation results of a buck boost converter, MPPT algorithm (P & O method) for solar PV module and closed loop PI control system for obtaining constant 12 V and 24 V DC output voltage at DC bus.

The proposed methodology is to extract maximum DC power from solar PV system and it is directly fed to DC load or DC Nano grid.

Aim of a paper

What is Nano grid?

It is a small-scale power supply network that is designed to provide power for a small community.

It comprises of various small power generating sources that makes it highly flexible and efficient.

It is connected to both the local generating units and the utility grid thus preventing power outages.

Excess power can be sold to the utility grid.

Size of the Micro grid may range from housing estate to municipal regions.Nowadays, energy generate in form of clean, efficient, and environmentally friendly sources has

become one of the major challenges for engineers and scientists [1].

Introduction of Nano grid

Applications of DC Voltage

Fig.1. Hair dryers

Fig.2. Ovens

Fig.3. Laptop chargers

Fig.4. Mobile chargers

Recently the growth of DC operative home appliances like mobile and lap top chargers, ovens and hair dryer’s are increasing

Therefore a DC/DC converter is an efficient way to meet the electricity need from the local DER and helps in improving the system efficiency

Micro grid could be the answer to our energy crisis.Transmission losses gets highly reduced.Micro grid results in substantial savings and cuts emissions without

major changes to lifestyles.Provide high quality and reliable energy supply to critical loadsCO2 Emissions are reduced.

The Need of Micro grid

The efficiency of solar cells depends on many factors such as

1. Temperature2. Insolation 3. Spectral characteristics of sunlight 4. Dirt5. Shadow and so on.

In addressing the poor efficiency of PV system some methods are proposed for improving an efficiency of solar PV system among by implementing a new concept called “maximum power point tracking” (MPPT).

The DC/DC converter is responsible for transferring maximum power from the solar PV module to the load. A MPPT is used for extracting the maximum power from the solar PV module and transferring that power to the load [4].

Environmental aspects

Poly crystalline solar PV moduleVmpp =35.9 V, Impp= 8.22 A

 

Mono crystalline solar PV moduleVmpp =35.7 V, Impp= 7.99 A

 

Thin film solar PV moduleVmpp =79.0 V, Impp= 1.9 A 

MPPT(using P & O algorithm)

MPPT(Using P & O

algorithm)

MPPT(using P & O algorithm)

DC/DC buck boost converter

DC/DC buck boost converter

DC/DC buck boost converter

DC/DC buck converter

Charging station for

mobiles

Charging station for

mobiles

Battery energy storage (BES)

Battery energy storage (BES)

24 V DC bus bar 

12 V DC  

24 V DC  

Vmpp =71.8 V  

Vmpp =71.4 V  

Impp =3.8 A

 

Schematic layout of DC Nano grid integrated with solar PV generation

Solar PV module

DC load

VI

MPPT algorithm and duty cycle modification (PI controller)

DC/DC converters(Buck, Boost,

Buck- Boost, Cuk) Converter)

Pictorial view of DC Nano grid with MPPT and PI controller

Power delivered by a module depends on the load connected to the module.

MPPT is algorithm that included in charge controllers used for extracting maximum available power from PV module under certain conditions.

The voltage at which PV module can produce

maximum power is called ‘maximum power point’ or peak power voltage.

MPPT is most effective under, cold weather, cloudy or hazy days.

There are large number of algorithms that are able to track MPPs.

Simulation of DC Nano grid integrated with monocrystalline solar PV module

Simulink Model of DC DC converter

Fig. 5. Simulink diagram of closed loop buck boost converter with PI controller

Recently, the deployment of DC appliances is exponentially increasing in all sectors like, industrial, commercial and domestic customers.

In addition, the solar PV module generates DC power and therefore it can be directly fed to DC load through DC/DC converter to minimize the conversion losses and improve power quality and efficiency.

Output voltage of buck boost converter is define as below.

𝑽 𝒐𝒖𝒕=−𝑽 𝒊𝒏∗𝑲(𝟏−𝑲 )

Fig. 6. I-V Characteristic of mono crystalline 285 W solar PV module

Fig. 7. P-V Characteristic of mono crystalline 285 W solar PV module

Characteristics of Mono Crystalline Solar PV module

Fig. 8. DC 12 V output voltage of buck boost converter Fig. 9. DC 24 V output voltage of buck boost converter

Output Voltage of Buck Boost Converter

This small level DC output voltage is directly fed to DC equipment’s like, (laptop battery, mobile charger and battery charging).

Sr. No. Advantages Disadvantages

1 Significant environmental benefits made possible by the use of low or zero emission generators.

Electrical energy needs to be stored in battery banks thus requiring more space and maintenance.

2 The use of both electricity and heat permitted by the close proximity of the generator to the user, thereby increasing the overall energy efficiency.

Resynchronization with the utility grid is difficult.

3 Nano grid protection is one of the most important challenges facing the implementation of Nano grids.

Advantages & Disadvantages of Nano grid

05/03/2023

To investigate full-scale development, field demonstration, experimental performance evaluation of frequency and voltage control methods under various operation modes.

Transition between grid connected and islanded modes on interaction phenomena between distribution generation and high penetration of distributed generation.

Transformation of Microgrid system today into the intelligent, robust energy delivery system in the future by providing significant reliability and security benefits.

Future Directions on Nano grid Research

Conclusion This paper simulates the DC-DC converter for application of DC Nano grid, at two voltage levels: 12 V &

24 V DC output voltages from buck boost converter.

This small level DC output voltage is used for small home appliances load.

The constant DC output voltage is obtained through two level using PI controller and MPPT algorithm for track maximum power from solar PV module.

The simulation results demonstrate the buck-book converter application for maintain constant voltage at DC bus irrespective of variation of solar PV generation.

Also it improves the system efficiency by reducing no. of conversions.

References1. A. Safari and S. Mekhilef, “Simulation and Hardware Implementation of Incremental Conductance MPPT

With Direct Control Method Using Cuk Converter”, IEEE Trans. Ind. Electron, vol. 58, no. 4, pp. 1154 – 1161, Apr. 2011.

2. W. Xiao, W. G. Dunford, P. R. Palmer, and A. Capel, “Regulation of photovoltaic voltage,” IEEE Trans. Ind. Electron., vol. 54, no. 3, pp. 1365– 1374, Jun. 2007.

3. K. K. Kalyan, R Bhaskar, and H. Koti, “Implementation of MPPT algorithm for solar photovoltaic cell by comparing short circuit method and incremental conductance method,” Science Direct, The 7th Inter. Conf. Interdisciplinary in Engineering (INTER-ENG 2013), Procedia Technology 12, pp. 705-715, 2013.

4. K. Y. Chen, T. J. Liang, J. F. Chen, “Novel maximum power-point tracking controller for photovoltaic energy conversion system” IEEE Trans. on Ind. Electro., vol. 48, no. 3, pp.594-601, Jun. 2001.

5. S. Kjaer, J. Pedersen, and F. Blaabjerg, “A review of single-phase grid connected inverters for photovoltaic modules,” IEEE Trans. on Ind. App., vol. 41, no. 5, pp. 1292–1306, 2005.

6. E. Koutroulis, K. Kalaitzakis, and N. C. Voulgaris, “Development of a microcontroller-based, photovoltaic maximum power point tracking control system,” IEEE Trans. Power Electron., vol. 16, no. 1, pp. 46–54, Jan. 2001.

7. E. Koutroulis, K. Kalaitzakis, and N. C. Voulgaris, “Development of a microcontroller-based, photovoltaic maximum power point tracking control system,” IEEE Trans. Power Electron., vol. 16, no. 1, pp. 46–54, Jan. 2001.

THANKS