GRID

Chief Engineer, SystemsMarch 2011

HVDC Grids:

A View to StandardisationCarl Barker

HVDC Grids: A View to Standardisation – March 2011 - P 2

Agenda

Why DC Transmission? Page 3

What are DC Grids? Page 6

How will DC Grids Evolve? Page 11

DC Grid Standardisation Page 13

HVDC Grids: A View to Standardisation – March 2011 - P 3

Why DC Transmission?

HVDC transmission is the correct technology for bulk submarine energy transfer.

AC

DC

Charges and DischargesEvery Half Cycle

Only Charges the Cable Once

HVDC Grids: A View to Standardisation – March 2011 - P 4

Why DC Transmission?

Basic Structure of VSC Transmission System

t

Idc

t

ii

Iact

i

Iac

Idc= V1- V2R

DC transmissionline

Q1 Q2P

VSC VSC

Station 1 Station 2

V1 V2

IC1

Network1

Network2

HVDC Grids: A View to Standardisation – March 2011 - P 5

Agenda

Why DC Transmission? Page 3

What are DC Grids? Page 6

How will DC Grids Evolve? Page 11

DC Grid Standardisation Page 13

HVDC Grids: A View to Standardisation – March 2011 - P 6

What are “DC Grids”?

• “DC Grids” – Multiple converters connecting AC power networks to a DC power network

• “DC Grids” – Permit the economic transfer of power over buried cables reducing environmental impact

• “DC Grids” – Permits economic bulk transfer over large distances

• “DC Grids” – Reduce the number of AC/DC Conversions therefore reduce losses

HVDC Grids: A View to Standardisation – March 2011 - P 7

132kV

400V400V400V

11kV11kV

400V400V400V

11kV11kV

DC Grid Configurations: Point-to-point System

HVDC Grids: A View to Standardisation – March 2011 - P 8

132kV

400V400V400V

11kV11kV

400V400V400V

11kV11kV

DC Grid Configurations: Radial System

HVDC Grids: A View to Standardisation – March 2011 - P 9

132kV

400V400V400V

11kV11kV

400V400V400V

11kV11kV

DC Grid Configurations: Meshed System

HVDC Grids: A View to Standardisation – March 2011 - P 10

Agenda

Why DC Transmission? Page 3

What are DC Grids? Page 6

How will DC Grids Evolve? Page 11

DC Grid Standardisation Page 13

HVDC Grids: A View to Standardisation – March 2011 - P 11

How will DC Grids Evolve?

• Large pan-European grids− Strategic all encompassing planning at the outset

• Four, five, six terminal grids− Small independent DC grids developing ‘organically’

“DC Grids” require rules in the same way that AC grids operate within “AC Grid Codes”

HVDC Grids: A View to Standardisation – March 2011 - P 12

Agenda

Why DC Transmission? Page 3

What are DC Grids? Page 6

How will DC Grids Evolve? Page 8

DC Grid Standardisation Page 13

HVDC Grids: A View to Standardisation – March 2011 - P 13

Do We Need to Standardise?

Purpose of Standards

− Reduce costs (design one build many, long run cost reductions etc.)

− Improve asset availability through improved maintainability

(common or interchangeable spares, common tooling etc.)− Support interoperability− Allowing interconnected systems to be built incrementally

and by different equipment suppliers, thus support

incremental investment plans and avoid “stranded assets”− Allow separation of cable and converter procurement thus

allowing buyers to take advantage of the increasing

number of HVDC cable manufacturers

HVDC Grids: A View to Standardisation – March 2011 - P 14

Functional Specifications

• AC/DC Converters

• HVDC Cables

• DC Breakers

• DC-DC Converters

• Dump Resistor

Equipment that should have a common functional specification

HVDC Grids: A View to Standardisation – March 2011 - P 15

Design Specification

• Topology?− Symmetric Monopole− Monopole− Bipole

• DC Voltage (nominal, steady-state and transient range)

• Fault Current Contribution

• Multi-terminal DC Protection

• Multi-terminal DC control*

*Barker CD, Whitehouse RS, ‘AUTONOMOUS CONVERTER CONTROL IN A MULTI-TERMINAL HVDC SYSTEM’, IET, ACDC 2010

Equipment that should be defined at the initial design stage

HVDC Grids: A View to Standardisation – March 2011 - P 16

DC Grid Standardisation Activities

• International recommendations being created;− CENELEC - Four, five, six terminal grids− Cigrè B4-52 - Large pan-European grids

• Cigrè have just approved five further DC grid working groups;− B4-56 Guidelines for the preparation of “connection agreements” or

“Grid Codes” for HVDC grids

− B4-57 Guide for the development of models for HVDC converters in a HVDC grid

− B4-58 Devices for load flow control and methodologies for direct voltage control in a meshed HVDC Grid

− B4-59 Devices for load flow control and methodologies for direct voltage control in a meshed HVDC Grid

− B4-60 Designing HVDC Grids for Optimal Reliability and Availability performance

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