EMVT 12 september - Pavol Bauer - TU Delft

1Challenge the futureEPP

Electrical Power Processing

Met EMVT op Zee

P Bauer



Content

• Introduction

• Renewable energies offshore

• Wave energy innovation

• Need for the DC grids



Real available solar energy per month

Data: NASA



4

Real available wind energy per month

Data: NASA



5

Data: NASA



6



• Wind energy offshore• Wave energy

Collection system



• Higher average wind speeds at sea • Space limitations on shore• The turbines will on average have a larger

diameters and rated powers• Less turbulence and lower wind shear• Erection and maintenance will be more expensive• Turbine noise will probably not be an important

issue• Submarine electrical connection to shore • The farm will be difficult to access during periods

with high windsEPP




9

gear-ASGbox

f

a) direct grid connection(normal plant for grid operation)

n= (1-s) f/p s~ 0...0.8 (output dependent)inductive reactive power consumer

~

1) with thyristor converter 2) with pulse inverter

n~ 0.8 1.2 f/p (controllable)1) inductive reactive power consumer

gear-box

b) grid connection via direct-current intermediate circuit

ASG

~

f

2) controllable reactive power output

DC

c) grid connection via direct ac converter

inductive reactive power consumer

gear-box

n~ 0.8 1.2 f/p (controllable)~

ASGf

d) dynamic slip control

(output dependent, dynamic)

gear-box

n= (1-s) f/p s~ 0... 0.1... (0.3)~

ASGf


e) oversynchronous static Kraemer system


gear-box

n~ 1...1.3 f/p (controllable)~

ASGf

n

n

n

n

n

box

controllable reactive power outputn~ .8...1.2 f/p (controllable)~

f) double fed asynchronous generator

gear-ASG

n f

controllable reactive power outputn= f/p

boxgear-

SGn f

g) direct grid connection

h) coupling to direct current grid

SGgear-box

n~ 0.5...1.2 n

n uDC

~ N

~n~ 0.5...1.2 f/p (controllable)

i) grid connection via direct-current intermediate circuit

ngear-box SG

f


1) inductive reactive power consumer2) controllable reactive power output

n~ 0.5...1.2 f/p (controllable)

1) with thyristor converter 2) with pulse inverterj) grid connection via direct-current intermediate circuit

~

2) controllable reactive power output1) inductive reactive power consumer

nSG

f

DC

DC

k) grid connection via direct-current intermediate circuit

~


n~ 0.6...1.2 f/p (controllable) 1) inductive reactive power consumer2) controllable reactive power output

n

DC

f

l) grid connection via direct ac converter

~n~ 0.8...1.2 f/p (controllable) (partial) reactive power consumer

n f

conversion system with asynchronous generator (ASG)conversion system with synchronous generator (SG)

sho r

t-ci

rcui

t ro

tor

mac

hine

ssl

ip r

ing

roto

r m

achi

nes

perm

anen

tly

exci

ted

mac

hine

sm

achi

nes

wit

h ex

cita

tion

sys

tem

(normal plant for independent operation)

*

*

*



10



11



12



Introduction wave



IntroductionWave generators – Wave Dragon



IntroductionWave generators – Pelamis



IntroductionWave generators – Oscillating Water Column



IntroductionWave generators – Oyster



Introduction waveWave generators – Archimedes Wave Swing



IntroductionWave Generators – EAPWEC

(1)

(2) (3)

“Snake” made of rolled DE material and filled with water



IntroductionElectro Active Polymer – Dielectric Elastomer (DE)

• Actuator - If a voltage is applied to the electrodes electrostatic forces will squeeze the

dielectric elastomer material and reduce in thickness and expand in area

• Sensor - Stretching the DE material will change area and thickness resulting in a change

in capacitance which can be measured

• Generator - If a stretched DE film is charged and then relaxed the voltage will increase

significantly; converting mechanical energy to electrical energy

DE STRETCHED

DE CONTRACTED

contraction

� large capacitance

� low voltage

� low energy state

� small capacitance

� high voltage

� high energy state



Principle of operation

• Energy is generated as the charged electroactive polymer decreases in area and increases in thickness as it contracts

Variable capacitor generator

Energy = ½ Qo2 (1/Cr - 1/Cs)

C = εr εo x film area/film thickness

+ + + + +

_ _ _ _ _

+Vin (lo)+Vout(high)

EAP STRETCHED

+ + + + +_ _ _ _ _

+Vin (low)+Vout(high)

Dielectric Elastomer

Compliant Electrodes (2)

EAP CONTRACTED



Introduction

• Constant voltage

• Constant charge

• Constant electric field

Methods for Energy Harvesting

T

Cs

Cc

0

10 kV

0

Id

Ic

tcharge tdischarge

∆tc

∆td

∆qc

∆qd

• Current shape optimization for

the optimum energy harvesting

cycle



IntroductionPower Take Off System

• Low voltage DC bus of 800 V

• Maximum power output per segment 10 kW

• High power PEU required, 100 kW peak power rating

• Target efficiency of PEU >95%

• Bidirectional power flow capability of the PEU



Medium-voltage dc-dc topologies

1) Two Quadrant Converter – Boost-Buck (2QC)

2) Flying Capacitor Multilevel Converter (FCMC)

3) Cascade Multilevel Converter (CMC)

4) Boost-Buck Multilevel Converter (B/BMC)

5) Multiphase Boost-Buck Converter (MPC)

• Final decision will be made based on a total ranking of the converter based

on multiple criteria




• High efficiency at low switching

frequencies and low VDE

• Simple control

• Stacking of switches neccessary

• High current switches

• High current ripple through CDE

• Huge inductor size

1) Two Quadrant – Boost/Buck



V2V1

Lk

S3S1

S2 S4

S7S5

S6 S8

iLk

vT1 vT2

1:n

DAB1

DAB2

DABN

VBUSVGEN

DAB module

I1 I2

V1 V2

• Input parallel output series converter with DABs

• Very wide output voltage range

• Variable frequency trapezoidal control method for DABs



0 1000 2000 3000 4000 5000 600085

87

89

91

93

95

97

99

power [W]

eff

cie

ncy

[%]

parallelbypass

Comparison of parallel and bypass module

control method using efficiency curves

0 500 1000 1500 200085

87

89

91

93

95

97

99

power [W]

eff

cie

ncy

[%]

Efficiency curve of the module and

combination of parallel and bypass methods

– hybrid method

DAB

module 2

DAB

module 1

Controller

DAB

module 3

bypass

VGEN

c o n t r o l s i g n a l s




• DAB circuit for balancing of

intermediate capacitor

• Medium-voltage transformer

• ZCS and ZVS

• Low current switches

• Simple control

• Low current ripple through CDE

• Different control methods

• Transformer for every module

needed

• Low efficiency at low VDE

3) Cascade Multilevel



Chapter 17

Electric Utility Applications

• These applications are growing rapidly



• AC versus DC

string

G

G

G

star

~=

=~

DC

~=

DC

~

~=

=

G

G

=~

=~

DC

~=

~

G

=

G

~=

GG

~~==

40 / 80 kV6.25 MVA

80 kV(2 X 40 kV)

80 kV(2 X 40 kV)

4.16 / 40 kV6.25 MVA

150 kV

5 / 33 kV31.25 MVA

33 kV

150 kV

40 / 150 kV125 MVA

150 kV

33 / 150 kV125 MVA

40 / 150 kV125 MVA

40 / 80 kV6.25 MVA

40 / 80 kV125 MVA

10 kV(2 X 5 kV)4.16 / 10 kV

6.25 MVA

5 / 10 kV31.25 MVA

=≈

=≈

4.16 / 40 kV6.25 MVA

40 / 80 kV125 MVA

string

G G G

G

G

star

=~=~

~=

=~

~=

=~

~=

=~

~

~=

=

33 kV

5 / 33 kV6.25 MVA

150 kV

5 / 33 kV31.25 MVA

33 kV

150 kV

4.16 / 5 kV6.25 MVA

33 / 150 kV125 MVA

33 / 150 kV125 MVA

5 kV

4.16 / 5 kV6.25 MVA

Collection systems



31

Data: NASA


Electrical Power Processing Electrical

Maximum allowable load current asa function of cable length

Itot RI

R,maxI

l

maxI IR,max = Imax - IC

= Imax – U/wC’ length

Power Processing



33



Thank You for Your Attention

Any Questions?





• 1882

• 1882 The world’s first power transmission over a long distance was based on

DC. The first transmission was from Miesbach to Munich – by Oskar von Miller

and Marcel Deprez: 57 km, 1.4 kV

• 1945: World’s first DC transmission project by Siemens and AEG: 115 km

cable, mercury-arc based link from the power station Elbe/Elektrowerke AG to

Bewag/Berlin at 60 MW / ±200 kV, ready for commissioning, but then

transported to Russia …

History of DC power Transmission

• 1945

J.Dorn Siemens


Electrical Power Processing J.Dorn Siemens

HVDC advantages

Long overhead lines with high transmission Capacity,low transmission losses and reduced right-of-way

Cable transmissions with low losses and without limitation in length

Asynchronous grids can be interconnected

Increase of transmission capacity without increasing short circuit currents

Fast control of power flow, independent from AC conditions

Firewall against cascading disturbances, active power oscillation damping



J.Dorn Siemens

Worldwide installed capacity



J.Dorn Siemens

• HVDC Classic

• Line comutated CSC

• Thyristors with turn on

Capability only

• VSC HVDC

• Self commutated VSC

• Semiconductor Switches with torn

on and turn off - IGBT



HVDC Classic vs VSC



HVDC Applications



• Long distance overhead

• DC submarine cable

• Back to Back

HVDC Applications

J.Dorn Siemens



HVDC Transmission

• There are many such systems all over the world



HVDC Poles

• Each pole consists of 12-pulse converters



HVDC Transmission: 12-Pulse Waveforms



HVDC Transmission: Converters

• Inverter mode of operation



Control of HVDC Transmission System

• Inverter is operated at the minimum extinction angle and the rectifier in the current-control mode



Breakthrough



Thyristors



Thyristors en module 2x13


Electrical Power ProcessingChapter 17 Electric

VSC HVDC



Multilevel

reduced semiconductor voltage - Lower harmonic distortion- More levels possible (multi

level)



Multilevel

• Practical realization

σ

σ

α



Space vector multilevel


Electrical Power ProcessingChapter 17 Electric

A

B

A

B

A

B

A

B

A

B

A

B

A

B

A

B

A

B

A

B

A

B

A

B

B

A

VSC HVDC


Electrical Power ProcessingCopyright © 2003

Chapter 17 ElectricUtility Applications


Electrical Power ProcessingChapter 17 ElectricUtilityApplications



– Press-pack IGBT modules for the CTL converter.

ABB



Alsthom



Thank You for Your Attention

Any Questions?

Business

EMVT 12 september - Pavol Bauer - TU Delft