NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO FACILITATE INCREASED FACILITATE INCREASED FACILITATE INCREASED FACILITATE INCREASED LEVELS LEVELS LEVELS LEVELS OF DISTRIBUTED GENER OF DISTRIBUTED GENER OF DISTRIBUTED GENER OF DISTRIBUTED GENERATION ATION ATION ATION CONTRACT NUMBER: DG/DTI/00039/05/00 URN NUMBER: 06/1829
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NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO FACILITATE INCREASEDFACILITATE INCREASEDFACILITATE INCREASEDFACILITATE INCREASED LEVELS LEVELS LEVELS LEVELS OF DISTRIBUTED GENEROF DISTRIBUTED GENEROF DISTRIBUTED GENEROF DISTRIBUTED GENERATIONATIONATIONATION
CONTRACT NUMBER: DG/DTI/00039/05/00
URN NUMBER: 06/1829
The DTI drives our ambition of ‘prosperity for all’ by working to create the best environment for business success in the UK. We help people and companies become more productive by promoting enterprise, innovation and creativity.
We champion UK business at home and abroad. We invest heavily in world-class science and technology. We protect the rights of working people and consumers. And we stand up for fair and open markets in the UK, Europe and the world.
Page i
NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO NEW TECHNOLOGIES TO FACILITATE INCREASEDFACILITATE INCREASEDFACILITATE INCREASEDFACILITATE INCREASED LEVELS LEVELS LEVELS LEVELS OF DISTRIBUTED GENEROF DISTRIBUTED GENEROF DISTRIBUTED GENEROF DISTRIBUTED GENERATIONATIONATIONATION
CONTRACT NUMBCONTRACT NUMBCONTRACT NUMBCONTRACT NUMBER ER ER ER
This work was commissioned and managed by the DTI's Distributed Generation Programme in
support of the Technical Steering Group (TSG) of the Distributed Generation Co-ordinating
Group (DGCG). The DGCG is jointly chaired by DTI and Ofgem, and further information can be
found at www.distributed-generation.gov.uk
ContractorContractorContractorContractor
P B Power
The work described in this report was carried out under contract as part of the DTI Technology Programme: New
and Renewable Energy, which is managed by Future Energy Solutions. The views and judgements expressed in this report are those of the contractor and do not
necessarily reflect those of the DTI or Future Energy Solutions.
First published 2006
Crown Copyright 2006
Page ii
Project Steering Group SummaryProject Steering Group SummaryProject Steering Group SummaryProject Steering Group Summary
To implement the recommendations of the DTI/Ofgem report on Embedded Generation, a
Distributed Generation Co-ordinating Group (DGCG), together with a supporting Technical
Steering Group (TSG) was established. A number of workstreams were formed by the TSG -
one of which, Workstream 5 (WS5) is focussed on long-term network solutions. An issue
addressed by WS5 was to establish what new technology was likely to become available by
2010.
WS5 commissioned a Report, via Future Energy Solutions, from PB Power with the following
principal objectives:
1. To identify what new technologies are available or emerging (in UK and world-wide) to
facilitate increased levels of Distributed Generation (DG) in the time frame to 2010; and
2. To provide a summary of the status of emerging technologies to help inform decisions about what further work might be appropriate in this area.
The Report considered network-related technologies - including primary and secondary plant,
telecommunications and IT. Generation-related technologies were omitted except where they
formed part of a wider network solution. In compiling the Report the authors considered
technologies that may not yet be fully developed, commercially available, or are cost effective
but which would have the potential to be so by 2010.
The Report identified that the technologies likely to have the most impact on the connection of
additional generation were super-conducting fault current limiters, in-line voltage regulators,
micro-grid controllers and reactive power compensators such as SVCs, FACTs and STATCOMs.
Some of these technologies would be commercially available well before 2010, other may be
still at the ‘demonstrator’ stage by that time.
In commissioning the Report it was not the intention of WS5 to provide an exhaustive list of
emerging technologies, research, development and demonstration projects and initiatives
being undertaken by manufacturers. The intention was to understand what new technologies
were emerging to inform decisions on what might be done to eliminate barriers for the
introduction of DG. Whilst particular new technologies might be noted as being developed by
a certain manufacturer, it should not be interpreted as being solely developed by that
manufacturer or to be the only new technologies being developed by that manufacturer.
A number of areas were identified where additional work may be required to remove potential
barriers to the connection of additional generation. The successful connection and operation of
large quantities of distributed generation will require a high-speed reliable communications
network to be established. No standards were identified which cover communications
protocols between the substations and remote devices on the distribution system.
The Distribution Working Group (DWG) of the Energy Network Steering Group (ENSG) will
need to consider the issues raised in the report and ensure that they are taken into account in
AREVA is currently developing several new transformer technologies. Solid-state tap
changers are under development. These could be retrofitted to existing transformers
or could be fitted to new transformers. The main advantage could be the improved
reliability and lower maintenance requirements over existing mechanical devices. It is
expected that the tap changers would have full reverse power capability.
A two-position tap changer is also being developed for smaller distribution
transformers. This would give an increased range of operation by providing low/high
load positions, winter/ summer or load/generation positions. It was not disclosed
whether these could be retrofitted to existing transformers with off-load or fixed taps.
No details of the tap step size were provided. A large step size may restrict operation
in order to comply with Engineering Recommendation P28.
Page 9
4.2.1.24.2.1.24.2.1.24.2.1.2 Other Companies and InstitutionsOther Companies and InstitutionsOther Companies and InstitutionsOther Companies and Institutions
The EPSRC SuperGen Initiative1 claims limited benefits from superconducting
transformers. The main benefits are from the reduced size and reduced
environmental hazards. Due to the high efficiency of conventional transformers the
reduced losses of HTS transformers are not considered a major advantage.
The University of Canterbury (NZ) is in the process of developing an HTS transformer
in conjunction with CanterburyTX2. A resonating high voltage transformer has already
been constructed and utilised for testing other HV transformers. Advantages of the
HTS transformer are the use of liquid nitrogen as both a coolant for the HTS windings
and as a dielectric as opposed to oil. This reduces the environmental hazards and fire
risks. A special core design substantially reduces stray electric and magnetic fields,
thereby reducing interference with other equipment. The current carrying capacity is
higher, meaning that a HTS transformer could have four times the rating of a
conventional identically sized transformer. Voltage regulation is improved due to the
lower leakage reactance reducing the requirement for a tap changer. Fault levels
would be increased however. No cost indications or expected manufacturing dates
have been given.
Waukesha Electric Systems (US)3 is also developing an HTS transformer in its
dedicated R&D facility. Few details are given other than the perceived benefits of
reduced size and weight, no environmental or fire safety hazards, extended lifetime,
greater efficiency and 100% continuous overload capability. No cost indications or
expected manufacturing dates have been given.
SF6 insulated transformers are currently available from Mitsubishi Electric Ltd4. They
are available over a voltage range of 11kV to 33kV with a reduced footprint compared
to conventional dry-type transformers.
Dynamic Ratings (AUS)5 has developed dynamic transformer rating equipment that
provides the ability to utilise the full overload capability of the transformer. Optical
fibre temperature measurement is employed to determine the winding temperature
and provide an input to the dynamic rating and insulation ageing software. The
system provides transformer load monitoring and control, although the method of
controlling the load is not stated. A full system replaces all existing transformer
control equipment, including the AVC control and the pump and fan controls. It can
be fitted to new transformers or retro- fitted to existing transformers. Development
work is being undertaken on more advanced equipment. Existing products have
recently been installed on transformers on the Kansas City system in the US and a few
transformers in the UK. Although the technology is not new to the UK, it is not in
widespread use. It is being marketed in the UK by Wilson Transformers Ltd, an
Australian manufacturer.
Cooper Industries6 manufacture in-line voltage regulators for 2.4kV to 34.5kV systems.
These provide a 32 step ±10% tap range with ratings between 33kVA and 1MVA in
both directions. They are placed in series on a distribution circuit and provide
accurate voltage regulation of the downstream circuit section. These devices have
Page 10
been used by SP Powersystems in North Wales to allow increased amounts of
generation to be installed. They have also been installed by Scottish Hydro on the
11kV and 33kV systems, mainly to control the voltage profile on long circuits. They
have also been used to allow generation to be connected although problems were
experienced when loads and generators were connected onto the same circuit. For
this reason small SVCs are now being installed where required. They have been
included in this report as their use in the UK is not thought to be widespread. In-line
voltage regulators are in more common use in both Northern Ireland and the Republic
of Ireland where loads may be sparser than in Great Britain. Guidance on their use is
provided in ETR 126 ‘Guidelines for Actively Managing Voltage Levels Associated with
the Connection of a Single Distributed Generation Plant’7.
4.2.24.2.24.2.24.2.2 ReviewReviewReviewReview
HTS transformers are currently being developed by a number of companies and
institutions. They have a significantly higher power rating for the same footprint as a
conventional oil-filled or cast resin transformer. This may avoid the need to relocate
existing substations or build additional substations to accommodate load growth.
Fewer substations could therefore supply a wider area or increased load transfers
could be accommodated at lower voltage levels. Lower environmental hazards would
be realised due to the use of liquid nitrogen as opposed to oil, minimising fire risks
and disposal issues.
There would be less requirement for a tap changer on an HTS transformer due to the
lower reactances resulting in a low voltage drop. This would improve reliability by
reducing the maintenance but would also increase fault levels.
Disadvantages envisaged are more expensive cooling arrangements and higher plant
costs due to the use of superconducting materials. Integration into the existing
system would be relatively easy due to the smaller footprint of the transformers,
though space would be required for the cooling equipment. This equipment could
however be common to a number of HTS transformers, cables and other plant such as
fault current limiters (FCLs).
All these developments would allow space to be made available at existing
substations to accommodate additional switchgear or control equipment.
Dynamic transformer rating equipment is currently available and in service on
transformers between 50MVA and 333MVA, allowing closer control of the maximum
transformer load than at present and a possible means of postponing reinforcement
requirements. Potentially dynamic loading could increase the allowable loading by
10% to 20%. This figure would be dependent on ambient temperature, cooling
efficiency and previous loading conditions. Dynamic loading could also reduce the
allowable maximum loading under adverse conditions although under these
circumstances remedial action such as load shedding might be required.
In-line voltage regulators have been shown to allow the connection of additional
generation but are not thought to be widely used in Great Britain.
Page 11
4.2.34.2.34.2.34.2.3 SummarySummarySummarySummary
The following table summarises the features of the transformer technologies.
ManufacturerManufacturerManufacturerManufacturer Product or Product or Product or Product or
No tap wear allowing increased frequency of operation and ‘faster’ voltage control. Full reverse power capability.
AREVA
Two Position Tap Changer
Under development
Provides low/high load or load/generation positions for greater operational flexibility.
CanterburyTX Superconducting Power Transformers
Under development
Lower losses, smaller footprint, no oil required, and high overload capability.
More expensive cooling arrangements.
Tap changer requirements reduced. Possibility of low maintenance but higher fault levels.
Waukesha Electric Systems
Superconducting Power Transformers
Under development
Lower losses, smaller footprint, no oil required, and high overload capability.
More expensive cooling arrangements.
Tap changer requirements reduced. Possibility of low maintenance but higher fault levels.
Dynamic Ratings
Dynamic Rating Equipment
In use
Allows potentially higher loadings to be carried. Insulation ageing calculations also provided. Maximum loading dependent on environmental factors plus previous loading.
Cooper Industries
In-line Voltage Regulators
In use Regulate distribution system voltages, reverse power capability. In very limited use in Great Britain.
Mitsubishi Electric Ltd
SF6 Distribution Transformers
In use Smaller footprint than dry-type transformers.
4.34.34.34.3 Overhead Lines and CablesOverhead Lines and CablesOverhead Lines and CablesOverhead Lines and Cables
May not provide significant increase in capacity, requires thermocouples to be fitted to existing cables or installation of new cables. Could be employed on future cables if manufacturers incorporate optical fibre temperature measurement into cables.
Composite Technology Corporation
Composite Overhead Conductors
In use
Higher capacity for similar sized conductor, no special installations requirements, equally applicable at any voltage level.
4.44.44.44.4 SVCs, FACTs and STATCOMsSVCs, FACTs and STATCOMsSVCs, FACTs and STATCOMsSVCs, FACTs and STATCOMs
ABB currently produce FACTS and HVDC Light devices for high voltage transmission
and distribution solutions. ABB is not developing similar devices for use at
distribution voltage levels of 33kV and below as the company does not believe there is
sufficient demand and the relatively high costs would present a significant barrier to
their deployment.
The ABB HVDC Light system provides a DC link of up to 100MW between two remote
AC systems. This has been employed to connect a remote wind farm to the
transmission system in Gottland, Sweden. The cable link is 70km long with a rating of
50MW at 80kV. A DC link was selected due to the difficultly in building a new
transmission line as well as the ability of the system to improve power quality.
4.4.1.24.4.1.24.4.1.24.4.1.2 AREVAAREVAAREVAAREVA
AREVA is in the final stages of developing a compact STATCOM, C-STATCOM. The
first equipment is scheduled to go into service at the end of 2005. A single C-
STATCOM cabin has a steady state rating of ±10MVAr and up to five modules may be
combined to give ±50MVAr. The cabins will normally be connected to the power
system via a tertiary transformer winding. Connection voltages are expected to range
from 11kV to 132kV. The reactive power capability provides extremely fast voltage
control improving voltage regulation, flicker and power quality. They can also reduce
post fault oscillations and improve the ability to ride through faults. The addition of
energy storage provides full four quadrant operation. The required output is
maintained over a very wide voltage range whilst the dynamic capability of each
module is twice the steady state rating.
AREVA is also developing a new common range of SVCs that will be available for
tendering at the beginning of the second quarter of 2005. These provide similar
Page 15
benefits to STATCOMs; however, the STATCOM has some superior characteristics
whilst SVCs provide a lower cost solution.
4.4.1.34.4.1.34.4.1.34.4.1.3 Other Companies and InstitutionsOther Companies and InstitutionsOther Companies and InstitutionsOther Companies and Institutions
American Superconductors14 manufacture a range of static and rotary power systems
devices which are described below: -
• D-VAR – Dynamic VAR system similar to a STATCOM. Provides an
‘instantaneous’, continuous source of reactive power. Can be used to resolve
voltage stability issues, increase transfer capabilities, minimise voltage flicker,
improve fault ride through and improve steady state voltage regulation.
Already in use providing up to –37 to 97MVAr of reactive power mainly in the
US. Operates over 480V to 35kV with outputs of 1.0 to 8.0MVAr.
• SuperVAR – an HTS synchronous condenser. Due to the use of an HTS field
winding the unit is more efficient, compact and reliable compared to
conventional synchronous condensers. A ±10MVAr, 13.8kV unit is available
with maintenance costs of <$10k per annum. It provides steady state voltage
regulation, increases system inertia, responds to system transients and
generates no harmonic currents. It also provides a fault level contribution. The
transient rating is up to 8.0pu.
• D-SMES – Distributed Superconducting Magnetic Energy Storage system. Can
inject real and reactive power into the system, up to 3MW and 8MVAr
(18.4MVAR instantaneous) per unit. Fast response provides benefits during
voltage collapse and instability on systems between 69-500kV. The ability to
inject real power into the network may allow generators to ride through more
severe faults or provide a smoother transition to and from island mode
operation.
Scottish Hydro have installed SVCs at the distribution level in order to improve the
voltage control when generators are connected to the system. These are being
installed where in-line voltage regulators do not provide a wide enough range of
operation to accommodate the opposing demands of load and generation.
4.4.24.4.24.4.24.4.2 ReviewReviewReviewReview
FACTs technologies provide the opportunity to provide both steady state and dynamic
voltage support for a range of voltages and power levels. Power quality can be
enhanced and the reactive power capabilities could be utilised to reduce network
losses. The dynamic response could provide additional inertia or MVAr/voltage
support to reduce the effect of faults on local generators.
A variety of STATCOM products are available or due to go into production before
2010. These would provide improved steady state and dynamic voltage support for
the network. Some manufacturers provide the facility for injecting real power into the
network to improve the fault ride through characteristics.
Page 16
Distribution voltage SVCs are being installed by one DNO to overcome the limitations
of in-line voltage regulators.
4.4.34.4.34.4.34.4.3 SummarySummarySummarySummary
The following table summarises the features of the transformer technologies.
ManufacturerManufacturerManufacturerManufacturer Product or Product or Product or Product or
In use Provides steady state and dynamic MVAr capability reducing flicker, improving stability and regulation.
AREVA C-STATCOM Q4 2005
Improves system voltage regulation, provides steady state and dynamic reactive capability. Energy storage capability for four quadrant operation.
D-VAR (STATCOM) devices
In use Provides steady state and dynamic MVAr capability reducing flicker, improving stability and regulation.
SuperVAR HTS synchronous compensator
In use
Increases system inertia, no harmonic contribution, provides steady state regulation.
Increases system fault levels.
American Superconductors
D-SMES HTS Magnetic Energy Storage System
In use Provides real and reactive power injection during transients. Fast response.
4.54.54.54.5 Switchgear and Fault Current LimitersSwitchgear and Fault Current LimitersSwitchgear and Fault Current LimitersSwitchgear and Fault Current Limiters
ABB is continuously developing its range of switchgear products, covering most
distribution voltages. The main area of innovation is considered to be the use of new
or alternative materials. This could lead to more compact cubicles allowing additional
circuits to be installed in existing substations. This may generate interface problems
with existing equipment such as the need to re-route the existing cables. There is also
a possibility that cubicle sizes will increase if the use of SF6 as an insulator is
discontinued due to environmental concerns.
One barrier to the use of a manufacturer’s standard design equipment in the UK is the
requirement for UK specific Energy Networks Association Switchgear Assessment
Panel approval in addition to the internationally recognised standards. The UK-
specific requirements largely stem from the need to meet the requirements of the
Page 17
ESQCR and the Distribution Code. For example UK equipment typically has more
comprehensive interlocking than continental equipment. DNOs are however
purchasing larger quantities of switchgear from continental manufacturers.
An 11kV solid state circuit breaker has been developed and is installed at a substation
in Switzerland. It is expected that these would operate faster than conventional circuit
breakers. It has not reached the commercialisation state yet due to various issues
including the cooling requirements and cost of the unit.
An intelligent vacuum circuit breaker has been developed for medium voltage
applications. This incorporates all the measurement, protection and control functions
into the circuit breaker truck reducing the cabling required as well as providing an
Internet communications interface. This would allow control and monitoring via a
wide area corporate network or an Internet connection. The smaller size and reduced
number of parts allows space and cost savings. This would allow extra circuits to be
incorporated into existing substations whilst simplifying the installation requirements.
4.5.1.24.5.1.24.5.1.24.5.1.2 AREVAAREVAAREVAAREVA
A magnetic type fault current limiter has been developed. The prototype working
voltage ranges will be between 3.5kV and 33kV.
4.5.1.34.5.1.34.5.1.34.5.1.3 Other Companies and InstitutionsOther Companies and InstitutionsOther Companies and InstitutionsOther Companies and Institutions
Nexans15 have recently installed a 10MVA capacity HTS fault current limiter (FCL) on
an RWE 10kV network in Germany in May 2004. The next stage of development is for
a 110kV unit. HTS FCLs exhibit rapid resistance or reactance changes above defined
current limits. Excessive current levels force a change of state from superconducting
to resistive which results in a lower fault current. Conventional circuit breakers and
protection relays can then be used to isolate the faulted equipment.
EPRI is sponsoring a project16 to demonstrate an HTS FCL suitable for use on a 138kV
transmission network. The beta test version, currently being developed by Nexans, is
scheduled for installation in 2006 and will then undergo a one to two year test phase.
The EPSRC SuperGen Initiaitive1 anticipates that the first superconducting application
will be for fault current limiters that should be commercially available within 5 years.
They react more rapidly than any circuit breakers and are regarded as essential to
enable the incorporation of distributed generation into the grid system.
4.5.24.5.24.5.24.5.2 ReviewReviewReviewReview
Increased levels of distributed generation will typically result in increased system fault
levels. Fault current limiters could be employed to reduce the need to upgrade
switchgear fault ratings, and possibly allow the use of lower rated equipment in order
to reduce costs. It is considered that they could make a significant contribution to
allowing increased generation because of their ability to effectively split the network
or control fault flows.
Page 18
The future generation of fault current limiters will be fail-safe. HTS FCLs are inherently
fail-safe since the collapse of superconductivity is directly related to the current
density. No external systems are required to initiate operation, indeed failure of an
external system, such as the cooling, causes the FCL to operate.
Development is in the advanced stages with several prototypes in use at various
voltage levels. It is expected that these devices would be available by 2010.
Installation of a FCL could avoid the requirement to replace entire switchboards,
thereby reducing reinforcement costs.
An intelligent 11kV circuit breaker has been developed which incorporates all the
monitoring, control and protection functions inside the circuit breaker truck. All
functions are available via an Internet type interface which reduces installation costs.
New materials technologies are expected to provide smaller switchgear components
due to improvements in insulation properties. This may allow more equipment to be
installed in existing substations.
4.5.34.5.34.5.34.5.3 SummarySummarySummarySummary
The following table summarises the features of the FCL technologies.
ManufacturerManufacturerManufacturerManufacturer Product or Product or Product or Product or
Switchgear Improvements based on new materials technologies
Not given Smaller cubicle sizes, therefore more feeders per substation
Medium Voltage Intelligent VCB
Now
Incorporates measurement, protection and control functions into circuit breaker truck. Control and monitoring via internet interface.
ABB
Solid State Circuit Breaker
Not given Faster operation and reduced maintenance
AREVA Superconducting Fault Current Limiters
Under development
Failsafe operation, allows system operation at higher fault levels. Can avoid the need for asset replacement. Allows increased levels of generation to be connected.
Page 19
ManufacturerManufacturerManufacturerManufacturer Product or Product or Product or Product or
Allows system operation at higher fault levels. Can avoid the need for asset replacement. Allows increased levels of generation to be connected.
Fail safe operation.
Nexans Superconducting Fault Current Limiters
Under trial in several installations
Failsafe operation, allows system operation at higher fault levels. Can avoid the need for asset replacement. Allows increased levels of generation to be connected.
This section presents the results and analysis of the various searches for new
technologies applicable to secondary plant.
The technologies covered by secondary plant technologies include: -
• SCADA Systems and Substation Automation
• Communications Systems
Generation related technologies have been excluded from these studies except where
they form part of a wider system.
5.25.25.25.2 SCADA Systems and Substation AutomationSCADA Systems and Substation AutomationSCADA Systems and Substation AutomationSCADA Systems and Substation Automation
Fully integrated solutions with advanced functionality.
DNOs may only be using the basic product features.
AREVA e-terra SCADA/EMS
In use Fully integrated system allowing control over all system devices from individual generators to system wide power control.
Remsdaq CallistoIES In use
Wide variety of communications protocols and media. Interfaces with various plant items, both local and remote. Flexible inbuilt intelligence, possible to automatically schedule generation, change transformer taps etc.
GenAVC Approximately 12 months
Provides voltage set-point adjustment for systems with embedded generators. May double amount of generation that could be connected.
Econnect
Load Controller Approximately 10 months
Automatic control of loads to provide some voltage rise mitigation and/ or maximise on-site usage of energy/ minimum bought-in energy to provide economic benefit.
Range being extended to cover grid connected applications.
5.35.35.35.3 Communications SystemsCommunications SystemsCommunications SystemsCommunications Systems
6.46.46.46.4 Switchgear and Fault Current LimitersSwitchgear and Fault Current LimitersSwitchgear and Fault Current LimitersSwitchgear and Fault Current Limiters
This sections details the manufacturers and their technologies with likely benefits from section 5 in tabular format. It should be
noted that the results column ‘Potential to Allow Increased Generation’ are subjective. Factors considered when determining the
potential are the ability to control increasing quantities of distributed generation. Technologies which relieve system bottlenecks
have been classified as having a lower potential to allow additional generation to be connected.
7.17.17.17.1 SCADA Systems and Substation AutomationSCADA Systems and Substation AutomationSCADA Systems and Substation AutomationSCADA Systems and Substation Automation
Superconducting transformers are currently under development with no firm dates or
costs given for production units. It is considered that some units may be available
before 2010. There would be issues arising from the cooling system such as the
increased complexity and requirement for liquid nitrogen supplies. There would be
environmental benefits as insulating oils would not be required. They may allow
additional generation to be connected due to their improved voltage regulation
characteristics, but these would also result in higher fault levels.
Solid state tap changers are being developed which may provide more flexible system
operation. These may allow more generation to be connected if retrofitted to existing
transformers with limited reverse power capability. Costs were not available but it is
expected that production units would be available before 2010.
Two position tap changers may also provide greater system flexibility, especially if
they can replace existing fixed or off load tap changers. These would allow more
generation to be connected due to the larger voltage range. Costs were not available
but it is expected that production units would be available before 2010.
Dynamic rating equipment would allow the full temperature range, and therefore
power range, of transformers to be utilised. This equipment is in use outside the UK
and can be retrofitted. It may allow increased levels of distributed generation, but
only where network thermal capacity starts to constrain the allowable levels of
generation.
In-line voltage regulators have been shown to provide positive benefits and allowed
the connection of additional generation. They are not in widespread use in the Great
Britain but they have been included in this report due to the benefits provided.
8.28.28.28.2 Overhead Lines and CablesOverhead Lines and CablesOverhead Lines and CablesOverhead Lines and Cables
Superconducting power cables have been developed and are undergoing trials. No
costs or production dates were available. They would allow higher powers to be
transferred along the same cable corridor which may have benefits in congested
urban areas. The reduced impedance may allow more generation to be connected but
the advantages over conventional cables are considered to be marginal.
Dynamic conductor monitoring systems are in use outside the UK. They allow an
accurate cable rating to be determined which may increase the power transfer
capability of circuits. These systems may allow marginally more generation to be
connected where there are high levels of connected generation.
Page 39
Composite overhead conductors would allow existing overhead circuits to be
substantially up-rated. In areas where there is a high concentration of generation their
use may allow more generation to be connected.
8.38.38.38.3 SVCs, FSVCs, FSVCs, FSVCs, FACTS and STATCOMsACTS and STATCOMsACTS and STATCOMsACTS and STATCOMs
A variety of SVC and STATCOM type devices are available and use around the world
and in the UK at transmission voltage levels. Due to the cost these devices are
normally employed at transmission level. Smaller more cost effective devices are
becoming available which would allow improved steady state and dynamic system
performance at distribution voltage levels. They could allow the connection of
additional generation by improving the fault ride through capability and providing
additional voltage regulation. The relatively high costs of these devices are
considered to be a barrier, in the short term at least, to their widespread use in the UK.
Distribution voltage SVCs are being installed by one DNO where in-line voltage
regulators do not provide a sufficient degree of voltage control.
8.48.48.48.4 Switchgear and Fault Current LimitersSwitchgear and Fault Current LimitersSwitchgear and Fault Current LimitersSwitchgear and Fault Current Limiters
A number of superconducting FCLs are under development. It is expected that these
would be available before 2010. They could allow significant amounts of additional
generation to be connected to systems where there would otherwise be fault level
issues.
Intelligent circuit breakers are available which have all the necessary functionality built
in including Internet type interfaces to allow remote operation. These would not
directly allow more generation to be connected but may make new connections more
cost effective.
New material technologies are expected to provide more compact switchgear
components that may result in the ability to install more equipment in existing
substations. This in turn may allow the connection of more generation.
8.58.58.58.5 SCADA Systems and Substation AutomationSCADA Systems and Substation AutomationSCADA Systems and Substation AutomationSCADA Systems and Substation Automation
Several organisations and institutions21, 22, 23, 24 in the US are undertaking R&D on
micro-grid network controllers. These would provide real time control for all active
devices on a section of distribution network. They would provide an interface
between the complexity of the distribution network and the centralised DNO control
system. Such systems should provide a simplified system for connecting a variety of
low voltage generators (DCHP, solar, micro wind etc) into a local distribution system.
Centralised SCADA/EMS systems are being continually developed to provide more
functionality. Advanced features include wind speed prediction, control of individual
generators and wind farms and market modelling. The increased capabilities will
allow additional generation to be more easily integrated into the existing system.
Page 40
Improved methods of controlling the tap changers of 33kV/ 11kV (primary)
transformers are already developed and undergoing field trials on two distribution
networks. Power measurements are used to control the primary transformer tap
changer to enable the maximum generation to be connected whilst ensuring that all
voltages are maintained within acceptable limits. Studies undertaken to date indicate
that GenAVC™ could double the amount of generation that could be connected to a
network. It is expected to be in production in approximately 12 months.
Intelligent generation controllers are being developed that should allow improved
voltage control for systems incorporating generators. By optimising generator
operation the system should maximise the amount of generation that can be
connected to the system.
8.68.68.68.6 Communications SystemsCommunications SystemsCommunications SystemsCommunications Systems
No major communications related R&D activities were identified as part of this report.
New developments are utilising existing communications technologies to provide the
functionality required.
The main barrier to allowing increased amounts of generation is considered to be the
development of the communications infrastructure to support the needs of the various
technologies. Existing SCADA communications networks are considered to be
unreliable and too slow for the control of significant quantities of distributed
generation. As increased quantities of generation are installed a reliable, high speed
communications network may need to be established in order to provide the DNO
with sufficient levels of control and monitoring.
The suitability of existing communications protocols may need to be examined to
ensure compatibility between the DNOs and consumers’ equipment. IEC61850
specifies a communication standard for substation devices but not for devices located
elsewhere on the distribution system.
8.78.78.78.7 OthersOthersOthersOthers
A first generation expert system has been developed to evaluate connections options
for 11kV networks. Further software development and testing is underway to expand
the range of applicable voltages to 132kV. The system examines the impact of
proposed generation on voltage profiles and fault levels then identifies the most cost
effective connection.
More advanced design and analysis tools will be required in order that developers and
DNOs can design and operate networks comprising active management systems and
high levels of distributed generation more effectively.
Page 41
8.88.88.88.8 SummarySummarySummarySummary
Most manufacturers’ R&D programmes are market led. Therefore products will only
be developed if a market has been identified. Some manufacturers have reported
issues with identifying customers’ needs and the uncertainty of future energy system
policy changes.
From the reviews undertaken it has been concluded that the most influential
technologies, in terms of maximising the potential for new generation, that should be
available before 2010 are: -
• Super-conducting Fault Current Limiters
o These devices would potentially remove any fault level issues where
additional generation may result in existing switchgear being
overstressed.
• SVCs, FACTS and STATCOMs
o These devices have been used to resolve voltage regulation issues
where generation is present. They can also improve power quality
but their high cost may restrict their application.
• In-line Voltage Regulators (not yet in wide-spread use)
o Although in-line voltage regulators are in use in the UK and therefore
outside the scope of this report, it is considered that they can allow
significant quantities of additional generation to be installed. This,
together with their very limited use in the UK, has resulted in their
inclusion.
• Micro-grid Controllers
o First generation controllers will soon be available which allow
generators to be incorporated into distribution systems whilst
maintaining satisfactory voltage control.
A number of areas were identified where further work may be required in order to
remove any potential barriers to the connection of additional generation. These are: -
• Communications Networks
o The successful connection and operation of large quantities of
distributed generation will require a high speed reliable
communications network to be established.
• Communications Protocols
Page 42
o No standards were identified which covers communications
protocols between the substation and remote devices on the
distribution system.
The only overseas practice identified by manufacturers as being an improvement on
current UK practice was making fuller use of SCADA/EMS product features to improve
system operation and flexibility. Whilst this may allow additional generation to be
installed and easily controlled, the combination of the existing SCADA and
communications systems employed are not generally considered suitable for
controlling large numbers of distributed generators.
Page 43
9.9.9.9. REFERENCESREFERENCESREFERENCESREFERENCES
1 EPSRC SuperGen Initiative, Workshop on Future Technologies for a Sustainable Electricity System,
November 2003, http://www.econ.cam.ac.uk/dae/Supergen-workshop/programme.html 2 University of Canterbury website. http://www.comsdev.canterbury.ac.nz/news/2004/040310a.shtml
3 Waukesha Electric Systems. http://www.waukeshaelectric.com/
4 Mitsubishi Electric Ltd, http://www.mitsubishielectric.com.hk/mehk/p&m/MAR/transform/sf6gis.htm
5 Dynamic Ratings Selected by Kansas Utility, T&D World, July 2004
Demonstration of a Superconducting Fault Current Limiter, EPRI, Project P122.003,
http://www.epri.com/D2004/
17
ABB, www.abb.com
18
Econnect, www.econnect.co.uk
19
Remsdaq, www.remsdaq.com
Page 44
20 ScottishPower plc, Network Management Systems for Active Distribution Networks – a Feasibil ity
Study, K/EL/00310/REP, 2004. 21
NREL, Reliable, Low Cost Distributed System Generator/Utility System Interconnect,
www.nrel.gov/publications/
22
NREL, Innovative Distributed Power Interconnection and Control Systems,
www.nrel.gov/publications/
23
NREL, Intelligent Solutions for Distributed Power Technology, www.nrel.gov/publications/
24
Consortium for Electric Reliabil ity Technology Solutions, http://certs.lbl.gov/certs.html 25
IEC61850, Communication Networks and Systems in Substations, 2003
Page 45
APPENDIX A
Study Brief
Page 46
New Technologies – To Facilitate Increased Levels of Distributed Generation
Study Brief
Purposes of Study
1. To identify what new technologies are available or emerging (in UK and world-wide) to
facilitate increased levels of Distributed Generation (DG) in the time frame to 2010
2. To provide a summary of the status of emerging technologies to help inform decisions about
what further work might be appropriate in this area.
Approach to Study
The study will be carried out in three stages.
Kick-off Meeting
A draft study brief will be prepared prior to the kick-off meeting. This document will define the scope of
the work required to undertake a structured and well-managed study. The Brief will describe the
approach to the Study; Risks/Dependencies/Assumptions; Quality Assurance etc.
At the kick-off meeting with the WS Project Manager, the study brief will be reviewed and approved,
and the number of manufacturers to be interviewed will be agreed.
Information Gathering
This stage will comprise the bulk of the work. It will include the following activities: -
• Identification of possible manufacturers/contacts and preparation of the questionnaire for the
interview with manufacturers
• Review of international developments from the literature: DTI/DGCG commissioned reports,
IEE, IEEE, CIGRE, Tyndall Centre, EPRI, web sources etc. Note will be taken in particular of
earlier DGCG studies, ‘Survey Study of Status and Penetration Levels of Distributed
Generation (DG) in Europe and the US (stage one and two)’ by KEMA (K/EL/00306/02/REP)
and ‘Network Integration of Distributed Generation: International Research and Development’
by SPRU (K/EL/00307/REP)
• Discussions with specialists within PB Power
• Telephone discussions with academic contacts
• Administration of questionnaires and/or structured interviews with selected manufacturers
This will be a world-wide review. It is envisaged that the technologies to be covered would include
primary and secondary plant infrastructure, telecommunications and IT. These technologies may
not yet be fully developed, commercially available, or be cost effective, compared to more
traditional approaches, but they should have the potential to be so by 2010. Existing technologies
not currently employed in the UK will also be covered. Only network related technologies will be
covered, ie generation related technologies will be omitted. Specific technologies to be addressed
Page 47
could include wind generator control systems, SVC’s, FACTS and STACOM developments,
superconducting fault current limiters, in-line voltage regulators, substation automation and
integration of generator/voltage control, SCADA systems and associated communications.
Manufacturers to be contacted could include the following: -
1. ABB at Stone, Staffordshire for on-going developments in SVC (to stabilise voltage
fluctuations and provide grid interconnection); FACTS devices for wind generator
connections; Superconducting Fault Current Limiters etc
2. Siemens Power T&D Group at Manchester for developments in substation automation
systems
3. Peter Brotherhood based at Peterborough for innovations in designing and manufacturing
equipment for use in renewable energy applications
4. GE Wind Energy Systems for developments in wind turbines
5. VA Tech T&D for new switchgear developments
6. Eurowind Developments Limited for innovations in wind turbines
7. Alstom at Stafford
8. Thales Information Systems
The manufacturers to be contacted will be determined from the document reviews and discussion
with PB Power specialists in the UK and overseas.
Rev iew and Reporting
The final stage will consist of the following: -
• Review of information gathered and preparation of DRAFT report
• Review of comments from Work Stream
• Preparation of Final Report
The report will include: -
1) Tabulations of manufacturers and their products/technologies.
2) Classification of these technologies into functional groups.
3) Review and discussion of each of these groups of technologies covering:
• their function and applicability to the UK system.
• their potential to integrate more generation
• the ease with which they could be incorporated into existing systems and any issues which would
have to be addressed,
• their l ikely cost/benefit
• the timescales on which they are likely to become available
• a comparison of (advantages and disadvantages of) the different products / technologies
competing within each group
4) Conclusions about the impacts these technologies could have within the timescale of interest.
Page 48
Information that is commercially sensitive to a manufacturer will be presented in an appendix or
similar and would not be placed in the public domain.
Reports would be produced in either Microsoft Word or Adobe Acrobat format as required by the
workstream.
Assumptions
It is assumed that this work will build on previous reports delivered under the DTI New & Renewable
Energy Programme, and will not go back over the same ground. Material presented in earlier reports
will not have to be reiterated in detail.
Risks
A lot of the input for this report will come from the manufacturers. There will therefore be risks
associated with the quality and timeliness of the information provided. There may also be difficulties in
commercial confidentiality. This will be addressed by contacting the manufacturers ahead of sending
the questionnaire and carrying out a structured interview, in order to identify the correct individual to
approach, and to ensure that the purpose of the exercise is fully understood. The benefits to the
manufacturer in contributing to the report will be highlighted, and any confidentiality concerns
discussed and addressed. Any material which the manufacturers consider confidential will not be
published in the public domain report but may be included in a restricted appendix.
Staffing and QA
The majority of the work will be carried out by a senior engineer, Steve Ingram, who has
experience of carrying out previous studies for the DTI N&RE Programme, and meeting the
requirements of a DGCG workstream.
Guidance and peer review will be provided by Katherine Jackson and John Douglas. Katherine has
managed other DTI N&RE projects, and John has extensive experience of distribution network
technologies.
Timescales
It is intended to produce a Draft Final report by the 24th
September 2004 to allow it to be presented at
the workstream meeting on the 30th September. The Final version of the report will be issued in mid
October, assuming that workstream comments are received within approximately two weeks. This will
depend to some extent on the speed of response of the manufacturers
Page 49
APPENDIX B
Questionnaires sent to Manufacturers
Page 50
APPENDIX B –Questionnaires sent to Manufacturers
The following questionnaire was sent out to a number of manufacturers with UK offices.
Manufacturers Questionnaire
We have been asked by the Department of Trade and Industry (DTI) in the UK to establish the status
of the new technologies that could influence the power distribution industry over the next ten years.
The purpose of this study is to identify the potential new technologies that may be applied in the UK
and to enable them to concentrate their R&D funding on technologies that may have a commercial
future.
Specifically the DTI’s requirements are summarised as follows: -
“This will be a world-wide review. It is envisaged that the technologies to be covered would
include primary and secondary plant infrastructure, telecommunications and IT. These
technologies may not yet be fully developed, commercially available, or be cost effective,
compared to more traditional approaches, but they should have the potential to be so by
2010. Existing technologies not currently employed in the UK will also be covered. Only
network related technologies will be covered, ie generation related technologies will be
omitted. Specific technologies to be addressed could include wind generator control systems,
SVCs, FACTS and STATCOM developments, superconducting fault current limiters, in-line
voltage regulators, substation automation and integration of generator/voltage control,
SCADA systems and associated communications.”
We understand from publicity that your company may be involved in product development or R&D
which could enhance the current UK distribution system and allow the connection of increasing levels
of distributed generation.
As detailed in the covering e-mail we would like to meet to discuss your company’s plans for such
technologies. In order that we can have a useful discussion we have compiled some questions,
below, which we would use as a basis for any meeting: -
• Outline any current products which are used in overseas distribution systems which could
benefit the UK system
• Are any products in development that may increase the ability of distribution systems to
accept more distributed generation, or to delay reinforcement?
• If possible, discuss the company’s current areas of research on distribution technologies
• Outline the areas in which the company expects current distribution technologies to develop
over the next five years
Page 51
• Outline the areas in which the company intends to undertake research over the next five
years
The DTI is actively encouraging increased levels of distributed generation, and therefore the current
distribution system may require significant changes in order to satisfy future needs. Funding may be
available to support any technologies or R&D projects that aim to improve the capacity of the current
distribution system.
We acknowledge that there will almost certainly be confidentiality issues surrounding your research
and products. In order that the DTI gains the most benefit from this study we would be willing to abide
by a confidentiality agreement in order that sensitive information would not be disclosed. Such
information would be included in a report appendix but would not form part of the document released
into the public domain.
The following questionnaire was sent out to a number of manufacturers with no UK offices.
Sirs,
We have been asked by the Department of Trade and Industry (DTI) in the UK to establish the state
of the new technologies that could influence the power distribution industry over the next ten years. The purpose of this study is to identify the potential new technologies that may be applied in the UK
and to enable them to concentrate their R&D funding on technologies that may have a commercial future.
Specifically the DTI’s requirements are summarised as follows: -
“This will be a world-wide review. It is envisaged that the technologies to be covered would include
primary and secondary plant infrastructure, telecommunications and IT. These technologies may not yet be fully developed, commercially available, or be cost effective, compared to more traditional
approaches, but they should have the potential to be so by 2010. Existing technologies not currently employed in the UK will also be covered. Only network related technologies will be covered, ie
generation related technologies will be omitted. Specific technologies to be addressed could include wind generator control systems, SVCs, FACTS and STATCOM developments, superconducting fault
current limiters, in-l ine voltage regulators, substation automation and integration of generator/voltage control, SCADA systems and associated communications.”
We understand from your publicity that you are presently working on dynamic reactive compensation, high temperature superconductor cables and other methods of improving power quality.
Would you be able to confirm that you are still working on these technologies and when they are
expected to reach the commercial market?
We would also appreciate any information about any other exciting areas of research that you are undertaking that could be of interest to the power generation or power distribution industries.
We acknowledge that there may be confidentiality issues surrounding your research and products, but
would of course welcome any high level information that you would be prepared to share.