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HVDC PLUS HVDC PLUS HVDC PLUS −−−Technology, Technology, Technology, BenefitsBenefitsBenefits, , , ApplicationsApplicationsApplicationsPower Transmission and Distribution

London, 4th October 2007J. Dorn; [email protected]

The Smart WayHVDC PLUS – One Step Ahead

2 04.10.2007 Power Transmission and DistributionJ. Dorn, PTD H 1T6

HVDC Classic – HVDC PLUS

~=

=~

AC Grid 1

DC

HVDC Classic HVDC PLUS

Line-commutated current-sourced converter

Self-commutated voltage-sourced converter (VSC)

Thyristors with turn-on capability only

Semiconductor switches with turn-on and turn-off capability, e.g. IGBTs

AC Grid 2


HVDC Classic – HVDC PLUS

~=

=~

AC Grid 1

DC

HVDC Classic HVDC PLUS

AC Grid 2

C

A

G

G

E

C


General Features of VSC Technology

Grid access of weak AC networks

High dynamic performance

Independent control of active and reactive power

Supply of passive networks and black start capability

Small space requirements

Additional Features and Benefits of HVDC PLUS


VSC Technology – A look back



)

+Ud/2

-Ud/2

High harmonic distortion

High transient stresses resulting in HF noise

Desired voltage Realized voltage


The Multilevel Approach

Small voltage steps

Small steepness of steps


Modular Multilevel Converter - MMC

Low generation of harmonics

Low HF noise

Low switching losses

Uc

Uc

Uc

0

0

0

Uc

0


HVDC PLUS with MMC

Phase Unit

Modular Multilevel Converter


HVDC PLUS with MMC

Modular Multilevel Converter

Phase Unit


HVDC PLUS with MMC

Phase UnitSubmodule (SM)


States of Submodules

State 1 = (0,0) State 2 = (1,0) State 3 = (0,1)


Perfect Voltage Generation

AC and DC voltages controlled by converter leg voltages:

+Ud/2

-Ud/2

Uac


PLOTS : Graphs

1.000 1.010 1.020

-250 -200 -150 -100 -50

0 50

100 150 200 250

U [k

V]

+Ud -Ud US1 US2 US3

-2.00

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

I [kA

]

is1 is2 is3

-1.50

-1.25

-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

I [kA

]

i1p i2p i3p i1n i2n i3n

Simulation Results: 400 MW with about 200 Submodules per Converter Leg


Submodule Design

Phase UnitSubmodule


Voltage Balancing

Phase UnitSubmodule

PLUSCONTROL


Converter Reactors

Phase Unit

Parallel connection of three voltage sources

Damp balancing currents between different phases

Limit current gradient during severe faults


Line-to-Line DC Fault

Phase UnitSubmodule


Modular Design: Submodule


Pre-Assembled Subunit


Converter Leg with more than 200 Submodules


Typical Converter Arrangement for 400 MW


Optional Seismic Reinforcements


Main Tasks of PLUSCONTROL TM

Calculation of required converter leg voltages

Choice of submodules to be switched

Control of active and reactive power

Submodule voltage balancing control

1

2

n

SIMATIC TDCC&P System

SIMATIC TDCMeasuring System


MeasuringSystem 2

MeasuringSystem 1

Uz1P, Uz1N, Uz2P, Uz2N, Uz3P, Uz3N

Converter Control& Protection

System 2

Converter Control& Protection

System 1

1

1

N1P, N2P, N3P, N1N, N2N, N3N

TDM Bus 1TDM Bus 1TDM Bus 1TDM Bus 1

MMS

Current ControlSystem 1&2

6

6

TDM Bus 2TDM Bus 2

IdOrder, IqOrder,A1P, A2P, A3P, A1N, A2N, A3N

C&P Topology – Low Power Range


TDM

Bus

2TD

M B

us 3

TDM

Bus

2TD

M B

us 3

TDM

Bus

2TD

MBu

s 3

TDM

Bus

2TD

MBu

s 3

TDM

Bus

2TD

MB

us 3

TDM

Bus

2TD

MB

us 3

TDM

Bus

2TD

MB

us 3

TDM

Bus

2TD

MB

us 3

TDM

Bus

2TD

MBu

s 3

TDM

Bus

2TD

MBu

s 3

TDM

Bus

2TD

MBu

s 3

TDM

Bus

2TD

MBu

s 3

C&P Topology – High Power Range


Main Features of PLUSCONTROL TM

Standard 19 inch racks

Highest degree of modularity

Advanced redundancy concept

Hot plug capability of PCBs and fans

High submodule interfacing capability

High numerical and logical perfomance

Highly flexible

andhighly

reliable control system

Integration into proven SIMATIC TDC systems


Properties of MMC topology and benefits

High modularity in hardware and software

Low generation of harmonics

Low semiconductor switching frequency

Use of well-proven standard components

Sinus shaped AC voltage waveforms

Easy scalability

Reduced number of primary components

Low rates of rise of current even during faults

High flexibility, economical from low to high power ratings

Only small or even no filters required

Low converter losses

High availability of state-of-the-art components Use of standard AC

transformersLow engineering efforts,

power range up to 1000MWHigh reliability,

low maintenance requirements

Robust system


Station Layout


VSC Systems with HVDC PLUS

DC cable transmission (XLPE cable)

DC overhead line transmission

Back-to-Back systems

Multi-terminal systems

STATCOM operation


Applications of HVDC PLUS

HVDC Systems up to 1000 MW where line-commutated converter have been used in the past

HVDC operation at very weak grids feasible

Grid access for regenerative energy sources, like wind farms

Supply of passive loads

Power supply of megacities

Co

ntrib

utio

n to

redu

ction

in C

O2

emissio

n


1

12

1

12

1

12

1

12

1

12

1

12

1

12

1

12

1

12

1

12

1

12

1

12

Converter Tower

System Test


System Test Transformers


Siemens will beMarket-Leader in VSC-based

HVDC Technology!

Thank you very much for your attention.

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