Power Electronics in New and Renewable Energy Systems Mohammad A. Abusara Lecturer in control and Power Electronics Renewable Energy Research Group College of Engineering, Mathematics, and Physical Sciences

Outline Microgrid Grid Connected Interleaved Inverter Exhaust Heat Energy Recovery Systems Marine Renewable Energy

Microgrid System

35kWHr lithium-ion batteries (60kVA Inverter) 100kW micro Gas Turbine

MicroGrid: Controller Structure

Microgrid Challenges and Features Challenges Maintain stability during connection, disconnection, load application/shedding Good Load sharing in island mode Good current quality in grid-connected mode Features Seamless transfer from grid-connected mode to island mode and vice versa Improved current quality Improved transient response

Microgrid-Practical Test

Microgrid-Practical Results

The effect of virtual impedance on improving current THD

Grid Connected Interleaved Inverter

Interleaved Concept  One channel is replaced by a number of channels connected in parallel  Switching instants are phase shifted equally over a switching period  Introduced for telecommunication power supplies (low voltage high current)

Interleaved Inverter- Advantages Smaller Power Switches Smaller capacitors Smaller Inductor

Novel DC/AC Grid Connected Interleaved Inverter Advantages over 2-level topology  Smaller C and hence so high output impedance to voltage harmonics (better current THD)  No need for a second L  Smaller in size

Controller Structure

System Modelling

Passive Damping For active damping Sampling frequency (35kHz) is only 1.47 to 3.2 times the natural resonance frequency Passive damping is possible (small capacitor current thanks to interleaved topology)

Passive Damping R Root locus, R = 0 ohmRoot locus, R = 0.5 ohm The varying parameter in the Root Locus is the grid impedance

Controller Design Phase Lag Controller Proportional Controller K(z) =10

Robust Digital Controller Immunity to Grid Impedance Variations Excellent Current Quality (THD=2.3%)

Interleaved Grid Connected Inverter

Exhaust Heat Energy Recovery Systems

Energy Recovery System Although it is a dominant prime mover and one of the most efficient power sources, a typical modern turbocharged Diesel engine still wastes significant amounts of fuel energy. The exhaust waste heat energy can be recovered and converted into useful electrical power

Components of Exhaust Recovery System Fuel Saving 5-7% Power Boost 10-15% Turbine + High speed alternatorPower Electronics

Exhaust Energy Recovery

Organic Rankin Cycle (ORC) System

ORC System Diagram

ORC Optimisation

Customers On road trucks Off road vehicleStationary power plants

Hybrid Turbocharger

Marine Renewable Energy

Marine Renewable Energy Systems Wave Tide

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