Power-Management Strategies for a Grid-Connected PV-FC Hybrid System

Power-Management Strategies for a Grid-Connected PV-FC Hybrid SystemUNDER THE GUIDANCE Mr.N.MAHENDER Assoc. Professor

Presented ByV.MAHESH M.TECH (PE) 11641D4304

AbstractThis project presents a method to operate a grid connected hybrid system. The hybrid system composed of a Photovoltaic (PV) array and a Proton exchange membrane fuel cell (PEMFC) is considered. The PV array normally uses a maximum power point tracking (MPPT) technique to continuously deliver the highest power to the load when variations in irradiation and temperature occur, which make it become an uncontrollable source. In coordination with PEMFC, the hybrid system output power becomes controllable. Two operation modes, the unit-power control (UPC) mode and the feeder-flow control (FFC) mode, can be applied to the hybrid system. The proposed operating strategy with a flexible operation mode change always operates the PV array at maximum output power and the PEMFC in its high efficiency performance band, thus improving the performance of system operation, enhancing system stability, and decreasing the number of operating mode changes.

Existing systemsRenewable energy is currently widely used. One of these resources is solar energy. The disadvantage of PV energy is that the PV output power depends on weather conditions and cell temperature, making it an uncontrollable source with help of only pv system load requirement fulfillment is difficult . Loads also suffer from the power interruption. Proposed systemsThe hybrid system can either be connected to the main grid or work autonomously with respect to the grid-connected mode or islanded mode, respectively. In the grid-connected mode, the hybrid source is connected to the main grid at the point of common coupling (PCC) to deliver power to the load. When load demand changes, the power supplied by the main grid and hybrid system must be properly changed. The power delivered from the main grid and PV array as well as PEMFC must be coordinated to meet load demand. The hybrid source has two control modes: 1) unit-power control (UPC) mode and feeder-flow control (FFC) mode.

In the UPC mode, variations of load demand are compensated by the main grid because the hybrid source output is regulated to reference power. Therefore, the reference value of the hybrid source output must be determined. In the FFC mode, the feeder flow is regulated to a constant, the extra load demand is picked up by the hybrid source, and, hence, the feeder reference power must be known.The proposed operating strategy is to coordinate the two control modes and determine the reference values of the UPC mode and FFC mode so that all constraints are satisfied. This operating strategy will minimize the number of operating mode changes, improve performance of the system operation, and enhance system stability.

MAIN BLOCK DIAGRAM Grid-connected PV-FC hybrid system.MODIFIED Block diagram Power generationPVPMFCPCCinverterLoadsDC/DCDC/DCPWMPWMMPPTPWMRenewable energy

Renewable energyisenergy which comes fromnatural resources such assunlight, wind, rain,tides, andgeothermal heat, which arerenewable(naturally replenished). About 16% of global final energy consumption comes from renewable, with 10% coming from traditional biomass, which is mainly used forheating, and 3.4% fromhydroelectricity. New renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) accounted for another 3% and are growing very rapidly.The share of renewables inelectricity generation is around 19%, with 16% of global electricity coming from hydroelectricity and 3% from new renewables.Mainstream forms of renewable energy

Wind powerHydropowerSolar energyBiomassBio fuelGeothermal energy

SOLAR ENERGYSolar energy is unique source of energy, which can be exploited in many waysBy direct conversion to a fuel by photosynthesis. By direct conversion to electricity by photovoltaic By direct conversion to electricity via. thermoelectric power system.

When sunlight strikes the surface of a pv cell, the electrical field provides momentum and direction to light-stimulated electrons, resulting in a flow of current when the solar cell is connected to an electrical load. PHOTOVOLTAICS

How much solar energy?

The surface receives about 47% of the total solar energy that reaches the Earth. Only this amount is usable. PV technology is not currently competitive with conventional electricity and other renewable because power generated by a PV system typically costs around 60p-70p/kwh. PV as a high cost technology requires government support to make its use more widespread. APPLICATIONSSolar photovoltaic systems have found applications in households, agriculture, telecommunications, defence and railways. FUTURE DEVELOMENTS 14

Schematic Diagram of a Fuel Cell 15

Fuel Cell Stack16Electro sorption (forming Pt-CH2OH, Pt2-CHOH species) of methanol onto Platinum layer deposited on MEA

Addition of oxygen to absorbed carbon containing intermediates generating CO2 Mechanism for Methanol Oxidation 17Operation of Fuel Cell

Types of Fuel Cells Fuel Cell Operating ConditionsAlkaline FC (AFC)Operates at room temp. to 80 0CApollo fuel cellProton Exchange Membrane FC (PEMFC)

Operates best at 60-90 0CHydrogen fuelOriginally developed by GE for spacePhosphoric Acid FC (PAFC)

Operates best at ~200 0CHydrogen fuelStationary energy storage device Molten Carbonate FC (MCFC)

Operates best at 550 0CNickel catalysts, ceramic separator membraneHydrocarbon fuels reformed in situSolid Oxide FC (SOFC)

Operates at 900 0CConducting ceramic oxide electrodesHydrocarbon fuels reformed in situDirect Methanol Fuel Cell (DMFC)Operates best at 60-90 0CMethanol FuelFor portable electronic devices19Experimental SectionPreparation of clay supportCasting of prepolymersyrup on wet clay supportGas phase nitration of the membrane at 1100 CAmination of the membrane using hydrazine hydrateQuaternizationby dichloroethaneand triethylamineStyrene, AIBN, BPO, DMA, Bulk polymerization at 700 C700 C, 12 hMembrane PreparationAdvantages Power managementStabilityReduce the no of modesEffective cost

Applications

In power distributionIn industrial areas

SIMULATION RESULTS

Fig. Operating strategy of the hybrid source.

Fig. Operating strategy of the whole system.

Fig. Change of operating modes.

Fig. The operating strategy of the hybrid source

Fig. Operating strategy of the whole system.

Fig. Change of operating modes.

ConclusionThis paper has presented an available method to operate a hybrid grid-connected system. The hybrid system, composed of a PV array and PEMFC, was considered. The operating strategy of the system is based on the UPC mode and FFC mode. The purposes of the proposed operating strategy presented in this paper are to determine the control mode, to minimize the number of mode changes, to operate PV at the maximum power point, and to operate the FC output in its high-efficiency performance band.Software requirements Out put SimulationToolsMatlab /simulink

REFERENCES

[1] T. Bocklisch, W. Schufft, and S. Bocklisch, Predictive and optimizing energy management of photovoltaic fuel cell hybrid systems with short time energy storage, in Proc. 4th Eur. Conf. PV-Hybrid and Mini- Grid, 2008, pp. 815.[2] J. Larmine and A. Dicks, Fuel Cell Systems Explained. New York: Wiley, 2003.[3] W. Xiao, W. Dunford, and A. Capel, A novel modeling method for photovoltaic cells, in Proc. IEEE 35th Annu. Power Electronics Specialists Conf., Jun. 2004, vol. 3, pp. 19501956.[4] D. Sera, R. Teodorescu, and P. Rodriguez, PV panel model based on datasheet values, in Proc. IEEE Int. Symp. Industrial Electronics, Jun. 47, 2007, pp. 23922396.[5] C. Wang, M. H. Nehrir, and S. R. Shaw, Dynamic models and model validation for PEM fuel cells using electrical circuits, IEEE Trans. Energy Convers., vol. 20, no. 2, pp. 442451, Jun. 2005.

THANK U