Presented By S.ROHITHA - 1075036

M.SAI KIRANMAI - 1075037

S.SARALA - 1075039

Under the guidance of

M.PALLAVI, M.TECH

SRI PADMAVATI MAHILA VISVAVIDYALAYAM

Head of the DepartmentProf. C. ESWAR REDDY M.TECH,PHD,FIE

The boost-inverter topology is used as a building block for a single-phase grid-connected fuel cell (FC) system offering low cost and compactness.

The proposed system incorporates battery-based energy storage and a dc–dc bidirectional converter to support the slow dynamics of the FC.

This system can operate either in a grid-connected or stand-alone mode.

In the grid-connected mode, the boost inverter is able to control the active (P) and reactive (Q) powers using an algorithm based on a second-order generalized integrator which provides a fast signal conditioning for single-phase systems.

ABSTRACT

EXISTING SYSTEM Fuel cell based power supply system

needs a power conditioner to convert the low dc output voltage generated by the fuel cell into usable ac voltage for any practical application.

Traditional two-stage power conditioner architecture consists of an active clamp full-bridge boost converter (ACFBC) for the dc-dc stage and a full-bridge sinusoidal pulse width modulation (SPWM) inverter for dc-ac stage.

EXISTING SYSTEM DRAWBACKS

Bulky Costly Relatively inefficient

PROPOSED SYSTEM A grid-connected single-phase FC system using a

single energy conversion stage only. The low-frequency current ripple is supplied by the

battery which minimizes the effects of such ripple being drawn directly from the FC itself.

In grid connected mode P,Q are controlled by the proposed algorithm SOGI.

The performance of a stand-alone FC system using the boost inverter with a bidirectional backup storage unit to support the slow dynamics of the FC and to cancel the ripple current that causes reduction of the lifetime and efficiency of the FC.

The proposed FC system includes Fuel Cell system Boost Inverter Backup energy storage unit Control of the Grid Connected Boost

Inverter

BLOCK DIAGRAM

EQUIVALENT CIRCUIT DIAGRAM OF GRID CONNECTED FUEL CELL SYSTEM

The boost inverter output voltage is indicated as Vo and Vg is the grid voltage. The active and reactive powers are expressedby

GENERAL STRUCTURE OF THE PROPOSED SYSTEM

Fuel CellElectrons are drawn from the anode to

the cathode through an external circuit, producing direct current electricity.

As the main difference among fuel cell types is the electrolyte, fuel cells are classified by the type of electrolyte they use followed by the difference in startup time ranging from 1 sec for PEMFC to 10 min for SOFC

Operation Of A Fuel Cell

Types Of Fuel Cells Proton exchange membrane fuel

cells (PEMFCs) Phosphoric acid fuel cell (PAFC) High-temperature fuel cells

SOFC MCFC

PEMFC

Applications• Power• Fuel cell electric vehicles (FCEVs)

Automobiles Buses Forklifts Motorcycles and bicycles Airplanes Boats Submarines

Boost Inverter The boost inverter consists of two bidirectional boost

converters and their outputs are connected in series.

Boost inverter(contd…) A double-loop control scheme is

chosen for the boost-inverter control being the most appropriate method to control the individual boost converters covering the wide range of operating points.

Backup Energy Storage Unit The functions of the backup energy storage

unit are divided into two parts. First, the backup unit is designed to

support the slow dynamics of the FC. Second, in order to protect the FC system,

the backup unit provides low-frequency ac current that is required from the boost inverter operation.

The backup unit comprises of a current-mode controlled bidirectional converter and a battery as the energy storage unit.

Simulation Block Diagram

Simulation ResultsOutput Voltages Of Boost Inverter

V1 V2 V0

Output at AC Grid

IgVg

Input Current Of Boost Inverter

I0

ADVANTAGES Low cost Compactness High power conversion efficiency

Reduced converter size Able to operate in stand-alone as well as in grid-connected mode

Conclusion The proposed FC system has a number of

attractive features, such as single power conversion stage with high efficiency, simplified topology, low cost, and able to operate in stand-alone as well as in grid-connected mode.

In the grid-connected mode, the single-phase FC system is able to control the active and reactive powers by a PQ control algorithm based on SOGI which offers a fast signal conditioning for single-phase systems.

It should be noted that the voltage-mode control adopted for the boost inverter may result in a distorted grid current (under given THD) if the grid voltage includes a harmonic component.

REFERENCES1. S. B. Kjaer, J. K. Pedersen, and F.

Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1292–1306, Sep./Oct. 2005.

2. J.-S. Lai, “Power conditioning circuit topologies,” IEEE Ind. Electron. Mag., vol. 3, no. 2, pp. 24–34, Jun. 2009.

3. Horizon Fuel Cell Technologies, H-Series PEMFC System User Guide(2010). [Online]. Available: http://www.horizonfuelcell.com