GE High Voltage Direct Current Systems

Today’s Environment

Globally the utility environment is becoming more complex and utilities are

having to manage new challenges such as:

• Increasing demand for electricity

• Connection of remote generation

• Growth of distant offshore wind

• Integration of variable renewable generation

• Need for security of supply

• Reduce carbon footprint

• Land costs becoming more expensive

• New right-of-way access permits increasing difficult to obtain

The only choice for many utilities is to restructure their grid systems to

manage these challenges. Utilities are looking for cost effective solutions to

transfer power and to improve the quality, stability and reliability of the grid

which will anticipate their needs for the next 20 to 50 years.

HVDC Overview

High Voltage Direct Current (HVDC) solutions are ideal for supporting existing

AC transmission systems or for building new power highways. HVDC is a

system which interconnects two AC networks, converting AC voltage to DC

voltage, and DC voltage to AC voltage utilizing power electronics technology.

HVDC systems enable transfer of power, interconnection of grids, integration

of renewables and maximize grid performance.

Move more power, further

Ultra HVDC can operate at voltages up to 800kV enabling bulk transport

of electricity over long distances. HVDC systems have lower losses than AC

systems and can transmit up to 3 times more power than AC networks. HVDC

systems are more economical than HVAC for schemes with transmission

distances more than approximately 700 km(~400 miles). The use of insulated

cables in both submarine and underground applications, in combination

with HVDC, allows more power to be transmitted across long water

crossings, or buried out of sight adjacent to roads, railways and tunnels,

which may accelerate the permitting process compared to AC or overhead

DC transmission alternatives.

Integrate renewables

HVDC is a versatile and flexible technology, making it an ideal solution for

integrating renewable energy in modern grids such as remote windfarms,

both offshore and onshore. HVDC can provide additional controllability to

network operators to support efficient management of transmission of

mixed energy sources, including the increasing use of renewables combined

with energy storage.

Interconnect grids

HVDC enables the exchange of energy between two AC networks. In some

cases, this is the only means of neighboring utilities exchanging energy

since they operate at different frequencies or may not be synchronized.

An HVDC interconnection has many benefits, such as allowing neighboring

utilities to reduce and share ‘spinning reserve’, giving access to other lower

cost sources of energy.

Improve quality, stability and maximize network performance

All HVDC solutions provide a 'firewall' to prevent disturbances propagating

from one network to another. They provide fast and highly controllable

power transfer and today can provide reactive power into the local AC

network to improve stability and quality.

The GE Advantage

GE is globally recognized for designing, manufacturing and delivering customized

HVDC solutions for utilities worldwide. GE offers two HVDC technologies, Line

Commutated Converters (LCC) and Voltage Source Converters (VSC), for a broad

range of applications and available in a range of schemes including overhead

line (point to point), back to back, submarine/land cable and offshore.

Every HVDC solution is tailored and designed based on a project-by-project

assessment of the customers’ individual requirements, whether it's for long

distance power transmission, energy trading between independent networks

or connection between asynchronous networks. GE offers the complete

package including early feasibility studies, project management from

network analysis and design, to commissioning. GE is globally recognized

for partnering with customers to deliver technically challenging projects for

more than 50 years and provides customers with the following benefits:

Robust leading edge technology designed and built in advanced

automated manufacturing and testing facilities to maximize

quality and system performance

• Customer value driven innovation built on foundational engineering

practices that have been developed for more than 50 years

• New, advanced automated manufacturing and test facilities delivering

precision, repeatability and quality to meet the exacting requirements of

the HVDC industry

• Significant investment in quality systems and resources including one of the

largest VSC HVDC demonstration laboratories in the world, state-of-the-art

valve test facilities and one of the only HVDC cable ageing laboratories in

the industry, ensuring superior technical performance of installed systems

• Pioneered flexible HVDC control methods, for complex applications such as

de-icing, and multi-terminal HVDC

Trusted project partner with a collaborative customer

engagement model, extensive technical domain expertise

resulting in optimized solutions that exceed customer

expectations

• Recognized in the industry as having one of the most flexible, engaging

and educational collaborative customer models among all HVDC

providers, ensuring transparency in all aspects of project execution

• Deep domain expertise, including multiple Uno Lamm award recipients

across our global HVDC centers in the USA, India and South Korea,

coordinated from our HVDC Center of Excellence in Stafford, UK

• Global EPC capability that leverages GE's combined transmission

and power generation project execution excellence through shared

partner networks, localized supply chain and industry leading project

management practices

State-of-the-art Model Based Design Control System that

minimizes project risk and ensures optimal and accurate

performance by direct deployment into the system software

• Model based design provides rapid technical responsiveness and support

to the customer throughout the project life

• Intuitive graphical interface allows fast, automatic, and error free code

generation from control models, providing a greater level of confidence to

the customer

• Easy integration of control system software with power system modelling

tools such as PSCAD® providing an accurate representation of the power

system performance for planning and troubleshooting analysis

• Control system hardware utilizing a modular design, based on

commercial-off-the-shelf components, which provides extensive

scalability to any project rating while maintaining quick system delivery

time and simple life-cycle management

GE’s HVDC Technologies

Line Commutated Converters

Line Commutated Converter is a mature cost effective HVDC technology

based on thyristor power semiconductors, which enables the bulk transfer

of power of up to 8 GW with low losses and inherent DC fault protection.

LCC is available as point to point overhead line and submarine/land cable

and is ideally suited for back to back schemes.

Voltage Source Converters

Voltage Source Converter is a newer technology based on power transistors

with a reduced footprint compared to LCC technology. VSC is an ideal

technology for submarine/land cable interconnection, integrating renewables,

offshore and urban infeed applications. VSC is available as point to point,

back to back, submarine/land cable and offshore schemes. VSC has distinct

technical advantages over the traditional LCC schemes because it creates

an AC waveform that allows the scheme to control real and reactive power

independently and transmit real power into a very weak AC network,

which is not possible with LCC.

HVDC Schemes

Back to Back Scheme

Suitable for frequency changing and asynchronous connections. This

scheme provides fast accurate power flow, limiting the spread of cascading

faults and provides increased system flexibility relative to new generation

requirements. Once interconnected, the two systems’ daily and seasonal

cost differences can also be optimized.

Point to Point Scheme

Commonly used for bulk transfer of power applications utilizing overhead

lines over long distances providing low cost, fully functional, reliable and

environmentally friendly way to transmit power.

Submarine/Land Cable  Scheme

Where the power exchange or transmission crosses water, or an

environmentally sensitive region, cables may be the favored method of

interconnection between the HVDC Converter Stations. HVDC transmission

is particularly attractive and may be the only technically feasible method of

transmitting power using cables.

HVDC Applications

Transferring Bulk Power Over Long distances

Challenge

Transfer large amounts of power from distant power sources, such as hydro

plants, to a load centre.

GE’s solution

GE’s HVDC LCC point to point scheme is ideal for the bulk transfer of

power utilizing overhead lines over long distances providing a fully flexible,

controllable and environmentally friendly solution for transmit power.

Benefits include

• Maximizing transmission of substantial power utilizing UHVDC up to 800kV

• Improves environment impact as a result of the smaller towers and right

of way requirements

• Increasing power capacity up to 3 times more than AC circuits

Interconnecting Grids

Challenge

Interconnect asynchronous AC electricity grids to enable energy exchange,

which provides dynamic reserve power support, relieve energy bottlenecks

and maximize the efficient use of available power.

GE’s solution

GE’s HVDC back to back schemes are ideal for interconnecting grids

operating at different frequencies, not synchronized, operating at high

power and in extreme temperatures up to +55° C.

Benefits include

• Exchanges energy between two unsynchronized AC systems

• Provides fully controllable and flexible dynamic reserve power support

• Manages fault propagation providing a power "firewall" between the

interconnected networks

HVDC Applications

Connecting Offshore Wind

Challenge

Bring power from distant wind farms to the onshore grid.

GE’s solution

GE's HVDC VSC technology is the most economical and feasible solution for

connecting submarine cable applications, such as offshore wind farms. GE’s

solution gives full control and flexibility in managing the intermittent and

variable generation.

Benefits include

• Provides a low loss solution, with the most efficient method of

transmission technology

• Enables the controllability of intermittent power

• Optimizes the use of submarine cables

Infeed Urban Areas

Challenge

To get power into congested cities to address increasing demand, lack of

power highways and difficulties with establishing rights of way for a new grid.

GE’s solution

GE’s VSC HVDC technology is ideally suited to provide controllable

and efficient power into congested areas where small footprint and

environmentally acceptable solutions are essential.

Benefits include

• Minimizes the visual impact of the power infeed on the local landscape

• Provides high levels of power injected directly to where it is needed

• Manages fault propagation providing a power "firewall" between the

interconnected networks

• Provides lowest loss solution, with the most efficient method of

transmission technology

Connecting Renewable Generation

Challenge

Bring power from remote renewable sources to load centres

GE’s solution

GE’s HVDC LCC and VSC are amongst the most economical and feasible

solutions for connecting renewable generation applications, such as wind,

hydro and solar power. GE’s solution gives full control and flexibility in

managing the power flow from the intermittent and variable generation to

the load.

Benefits include

• Provides a low loss solution, with the most efficient method of

transmission technology

• Enables the controllability of intermittent power

• Improves environment impact as a result of the smaller towers and right

of way requirements

• Increasing power capabilities up to 3 times more than AC circuits

Multi-terminal HVDC systems and DC Grids

Challenge

Interconnect three or more regions and power systems to facilitate power

exchange and trading, and to provide added system security, efficiency and

flexibility to the benefit of the overall grid.

GE’s solution

GE’s HVDC enables the interconnection of multiple HVDC converters

providing controllability of power flow and facilitates the future expansion

into HVDC grids.

Benefits include

• Better management and integration of renewable energy generation

• Increases grid security

• Enables cross border energy trading

• Provides more efficient network by reducing reliance on thermal generation