EE6009

POWER ELECTRONICS FOR RENEWABLE ENERGY

SYSTEMS

UNIT I INTRODUCTION Environmental aspects of electric energy conversion: impacts of renewable energy generation on environment (cost-GHG Emission) - Qualitative study of different renewable energy resources: Solar, wind, ocean, Biomass, Fuel cell, Hydrogen energy systems and hybrid renewable energy systems.

UNIT II ELECTRICAL MACHINES FOR RENEWABLE ENERGY CONVERSION Reference theory fundamentals-principle of operation and analysis: IG, PMSG, SCIG and DFIG.

UNIT III POWER CONVERTERS Solar: Block diagram of solar photo voltaic system -Principle of operation: line commutated converters (inversion-mode) - Boost and buck-boost converters- selection of inverter, battery sizing, array sizing Wind: Three phase AC voltage controllers- AC-DC-AC converters: uncontrolled rectifiers, PWM Inverters, Grid Interactive Inverters-matrix converters.

UNIT IV ANALYSIS OF WIND AND PV SYSTEMS

Stand alone operation of fixed and variable speed wind energy conversion systems and solar system Grid connection Issues -Grid integrated PMSG, SCIG Based WECS, grid Integrated solar system

UNIT V HYBRID RENEWABLE ENERGY SYSTEMS Need for Hybrid Systems- Range and type of Hybrid systems- Case studies of Wind-PV Maximum Power Point Tracking (MPPT)

UNIT II

ELECTRICAL MACHINES FOR RENEWABLE ENERGY CONVERSION

Reference theory fundamentals-principle of operation and analysis: IG, PMSG, SCIG and DFIG.

GENERATORS USED FOR WIND ENERGY CONVERSION SYSTEM● IG –power factor poor● SEIG- power factor improved● SCIG –constant speed WECS● DFIG(WRIG)- variable speed generator● PMSG –Permanent Magnet Synchronous Generator

Wind Turbine Generator Output Curve

Induction Generators● Same basic construction as squirrel-cage induction motors● Drive at a speed greater than the synchronous speed● Not started as a motor● Operated by wind turbines, steam turbines, etc.

ECE 441 9

Self Excited Induction Generator

Speed –Torque curve

Double Fed Induction Generator

PMSGAdvantages over the DFIG● The PMSG does not require DC excitation as the

magnetic field is produced by the permanent magnets rather than by the coil.

● Hence, the PMSG does not require slip rings and brushes, which reduces the weight, cost, losses, and maintenance

● PMSG, connected to the power electronic converter, can operate at low speeds; hence, a gearbox is not required

Classification of PMSGBased on the direction of the flux lines:● Radial flux PMSGs● Axial flux PMSGs and ● Transverse flux PMSGsBased on the location of the permanent magnets on the

rotor: ● Surface inset PMSGs● Surface mounted PMSGs and ● Interior PMSGs

Equivalent circuit of PMSG

Clarke’s Transformation● It transforms abc quantity into stationary and● coincides with phase a-axis and leads the by ● The equation with

The inverse

Park’s Transformation● It was proposed by Robert H. Park from MIT● There are wide ranges of application from machine

simulation, control, drives, etc. ● This transform is one of the most important application for

power engineers.

Park’s Transformation (2)

Park’s Transformation (3)● A vector in space can be seen from several coordinate

● We can change from one coordinate to another coordinate

Park’s Transformation (4)

Park’s Transformation (5)

The abc to dqo transformation

The abc to dqo transformation (2)

The abc to dqo transformation (3)

The abc to dqo transformation (3)

Commonly Used Reference Frame

Transformation Between Reference Frame

Application to Voltage Equation

Application to Voltage Equation(2)