Power Electronics as Efficient Interface in Dispersed Power generation Systems

Power Electronics as Efficient Interface in Dispersed Power generation SystemsBy Sai Chand (122527)Under the guidance of Uday bhaskarcontentsIntroductionCharaceristics of wind power conversionVariable speed wind turbinePower electronics for offshore wind farmsFuel cellsPower electronics in fuel cell systemsPower electronics in photovoltaic(pv) systemconclusion

introductionThe power system is a large number of dispersed generation units Renewable and non renewable sourcesAdv and disadv of renewable energyPower electronics being technolgy of efficiently converting electrical energyCharacteristics of wind power conversionThe aerodynamic power P, of a wind turbine given by

Wind turbine evolution and the main trend of power electronic conversion (blue indicates power level of converters) in the last 30 yearsVarible speed wind turbineThe wind turbine system keep an almost fixed speed by three methods, namely

system without power electronics,systems with partially rated power electronics,systems with full scale power electronic interfacing wind turbinessystem without power electronics,In this method the power is limited aerodynamically either by stall, active stall or pitch control which gives a speed variation of 1-2%

Wind turbine systems without power converter but with aerodynamic power control: (a) pitch controlled, (b) stall controlled, and (c) active stall controlled.systems with partially rated power electronics,In this method the induction generator with a wounded rotor. By the power electronic devices either the rotor resistance can be controlled or rotor currents can be controlled which gives speed range of 2-4%

Wind turbine topologies with partially rated power electronics:(a) rotor-resistance converter and (b) doubly fed induction generator

Wind turbine systems with full-scale power converters with activeand power control: (a) induction generator with gear, (b) synchronous generator with gear, (c) multipole synchronous generator, and (d) multipole permanent magnet synchronous generatorPower electronics for offshore wind turbineWind energy systems are developing towards higher capacity and offshore locationsFor long distance transmission of power from offshore farm, HVDC is a viable option Each wind turbine has its own power electronic converter

Wind farm arrangements: (a) a wind farm (40 turbines) with an ASVC unit, (b) a wind farm with a VSC based HVDC transmission and common ac-grid, and (c) a wind farm with an internal dc network and individual power control.Fuel cellsFuel cell is a chemical device, which produces electricity directly without any intermediate stage

Power electronics in fuel cell systemThe power conditioning system consists of dc/dc converter and a dc/ac inverter

Schematics of fuel cell power electronic conditioning systems. (a) dc/dc, dc link, and dc/ac conversion and (b) dc/ac, ac link, and ac/ac conversion.

Interface of a fuel cell consisting of a pushpull dc/dc converter with high-frequency transformer and a single-phase dc/ac inverters photovoltaic(pv) systemPV cell produces electrical power when exposd to sunlight

Model and characteristics of a PV cell. (a) Electrical model with current and voltages defined. (b) Electrical characteristic of the PV cell, exposed to a given amount of sunlight at a given temperature.Power electronics in pv systemsString inverters system Fly back current fed inverters

Fly-back current-fed (FBCF) inverter. A fly-back converter plus current source thyristor inverter.

Single stage inverter for multiple modulesconclusionMore and more dispersed generation units are being intigrated in to powersystems.power elecronic converters play a vital role in integration. The applications of power electronics in various generating dispersed units have been studied.References[1] S. Heier, Grid Integration of Wind Energy Conversion Systems. New York: Wiley, 1998.[2] E. Bossanyi, Wind Energy Handbook. New York: Wiley, 2000.[3] T. Markvart, Solar Electricity, 2nd ed. New York: Wiley, 2000.[4] N. Mohan, T. M. Undeland, andW. P. Robbins, Power Electronics-Converters, Applications and Design, 3rd ed. New York: Wiley, 2003.[5] P. Thocgersen and F. Blaabjerg, Adjustable speed drives in the nextdecade. Future steps in industry and academia, J. Electric Power Compon. Syst., vol. 32, no. 1, pp. 1332, 2004.[6] Z. Chen and E. Spooner, Voltage source inverters for high-power, variable- voltage dc power sources, Proc. Inst. Elect. Eng., vol. 148, no. 5, pp. 439447, Sept. 2001.[7] F. Blaabjerg and Z. Chen, Power electronics as an enabling technology for renewable energy integration, J. Power Electron., vol. 3, no. 2, pp. 8189, Apr. 2003.