Memorandum submitted by Areva
1. What should the Government's vision be
for Britain's electricity networks, if it is to meet the EU 2020
renewables target, and longer-term security of energy supply and
climate change goals?
1.1 A development vision should include the addition
of transmission and distribution capacity. Clearly this cannot
be achieved solely by an increase in the number of lines; options
include:
— Upgrades of lines (higher voltage, higher
currents)
— Optimized monitoring and control
— Novel technologies (eg DC transmission)
1.2 For this reason it is important to have
a vision, which enables the identification of the best option
to meet the challenge of distributing and balancing more renewable
power. Transmission and distribution expansions are not in contradiction
with efficiency improvements: any improvement in efficiency or
the influence of embedded generation is extremely unlikely to
alleviate the need for added electricity transmission capacity
due to the increasing share of electricity in the consumption
mix (the more electric society).
1.3 A larger share of renewables in the generation
mix will require increased electricity network flexibility. Since
system flexibility is not the clear duty of a single actor, a
guidance vision is required here as well. The vision could integrate
the following elements:
— Use of dynamic component rating: this
represents a more flexible use of existing assets, just expanding
their operation range from a very conservative to a physically
justifiable level.
— Power flow control: a way for the system
to adapt to a wider range of operational situations (due to the
fluctuations induced by renewables). This can be achieved by using
DC transmission and/or flexible AC transmission systems.
— Investigate architecture changes, especially
at sub-transmission level: systems have been laid out under a
set of assumptions which included low levels of decentralised
generation. Since these assumptions no longer hold, system architectures
need to be reviewed.
1.4 Conflict situations between regulation and
flexible system operation will need to be addressed.
1.5 Added interconnection to continental Europe
and Scandinavia is crucial in order to achieve a degree of "mutualisation"
of renewable generation which permits to overcome the difficulties
associated with the stochastic in-feeds by renewable generators.
2. How do we ensure the regulatory framework
is flexible enough to cope with uncertainty over the future generation
mix?
2.1 Bring up to date the historical regulatory
constraints concerning:
— Plug-and-Play micro-generation
— Benefits for participating in demand
side management
2.2 Reduce the impact of uncertainty and intermittence
on the transmission system security (caused by renewable energy
connection), install system reserve capabilities, such as energy
storage.
2.3 Rigid rules must be urgently reviewed relating
to the needs of consumers and the advent of new technology.
2.4 Implement real-time and dynamic electricity
pricing to maximise the customer benefits.
3. What are the technical, commercial
and regulatory barriers that need to be overcome to ensure sufficient
network capacity is in place to connect a large increase in onshore
renewables, particularly wind power, as well as new nuclear build
in the future? For example issues may include the use of locational
pricing, or the availability of skills.
3.1 On the technical side, a major issue is
standardisation and inter-compatibility of equipment as well as
harmonization of practises. In the current R&D landscape,
it is blatant that parallel activities too often result in uncoordinated
developments. Standards need to be actively encouraged. International
collaboration and co-ordination in the Transmission & Distribution
area is therefore a key requirement.
3.2 Significantly increase the connection capacity
at suitable sites to allow connection of new-build nuclear and/or
renewables. One technology solution to achieve this could be the
conversion of AC lines to DC—to facilitate an increase in
power transmitted down an existing corridor of up to 300%, using
the same towers and foundations.
3.3 On the regulatory side, solutions to avoid
placing the burden of connection to the network (and ensuring
adequate capacity) on individual generators should be investigated.
Since a large number of novel generators will need system developments,
the objective is to achieve a regional network expansion planning.
3.4 A commercial challenge might result from
the difference between the current short and uncertain planning
horizon and the difficulty to mobilise resources and skills needed
for the integration of renewables. A better long term view of
the entire sector would certainly help.
4. What are the issues the Government
and regulator must address to establish a cost-effective offshore
transmission regime?
4.1 Define who owns the responsibility for the
offshore to onshore transmission connection.
4.2 Define an environment where a cost-effective
offshore network around the coast of the UK (not just a single
point-to-point connection from offshore to onshore) can be built
with clearly defined responsibilities between the offshore generation
owner, the offshore network owner/operator and the land based
transmission grid owner/operator.
4.3 R&D support associated with technical
development and requirement of establishing an offshore transmission
system, including offshore transmission technologies and risk
management of security and reliability of the transmission system
connecting with large renewables.
5. What are the benefits and risks associated
with greater interconnection with other countries, and the proposed
"supergrid"?
5.1 Benefits:
Provide system stability and security, reduce
the required spinning/system reserve, and reduce the overall investment
cost for these items.
Part of a solution to "onshore" congestion
5.2 Risks
May experience more network disturbances caused
by other countries
Dependence on security of the interconnectors
Need for more coordination of network operations
between countries (which may be difficult to implement).
5.3 Challenges:
Achieving acceptable cost levels
Technical feasibility of off-shore terminals,
multi-terminal operation
Exposure to "imported" high energy
prices
6. What challenges will higher levels
of embedded and distributed generation create for Britain's electricity
networks?
Lower observability/controllability
Higher stress on the Distribution network
More dynamic network operation
Architectural challenges: fault-levels, distribution
of power flows, etc.
6.1 Definitions
Embedded generation is the term used for any
electricity generating plant that is connected to the regional
electricity distribution networks. These networks are owned and
operated by the Distribution Network Operators (DNOs). The DNOs
are the distribution arms of the former Public Electricity Suppliers
(PESs) and came into existence when the distribution and supply
licences were separated by the Utility Act (2000). At present,
most power generating plant in the UK is connected to the high-voltage
transmission system, which, in England and Wales, is owned and
operated by the National Grid Company.
6.2 UK distribution network capacity
While the distribution networks do have some
capacity for adding new embedded generation plant, the constraints
are significant: the usual scenario, as a result, is that the
locations where generation can be added do not coincide with the
optimum location for the proposed plant. This is particularly
true for renewable energy technologies, which, in most cases,
must be located where the renewable resource exists or is optimal.
During the period to 2010, current government
targets for renewable energy and CHP, if achieved or approached,
will result in more than 20-25GW of total capacity being added
to the distribution networks. Given the current configuration
of the networks, this level of additional capacity cannot be accommodated
without significant change.
6.3 Observations on Embedded Generation: Fault
Contribution
The addition of embedded generation will lead
to an increase in fault contribution within the point of connection
of the generation. This reduces the margin in hand of the equipment
already operating on the network busbars, disconnectors and switchgear.
In locations where equipment is already operating at or close
to it fault rating and new installation of embedded generation
can necessitate or accelerate the need for plant replacement to
ensure switchgear rating remain above the aggregate of fault levels
from the network and embedded generation. With the relatively
short planning times from concept to installation of new embedded
generation schemes imposes difficult network planning decisions
for the DNO's.
The use of fault current limiters between the
DNO network and the oncoming embedded generation provides a fault
buffer to ensure that any fault infeed into the network from embedded
generation is limited. This can assist in areas where network
fault levels are running close to the switchgear ratings and would
enable embedded generation to be installed without the need or
switchgear replacement.
Any current limiters would need to have a response
time consistent with the operating time of protection scheme and
that of the circuit breaker.
In the UK the DNO's are seeing an increase in
the dc time constant component of short circuit currents, this
is due in part to the solid mesh network, lower transformer losses
and standardised method of calculation. Normally within the DNO
network the ac component of the short circuit current is steady
state sinusoidal however for circuit breakers close to sources
of generation the ac component is a decaying to steady state sinusoidal
due the sub transient and transient components of the generator
reactance, which when superimposed upon by the high time constant
of the dc component can lead to delayed current zero duty for
the circuit breaker. With more embedded generation it is possible
that this will lead to a higher population of circuit breakers
close to these new generation sources with delayed current zero
duty.
6.4 Observations on Embedded Generation: Plant
Availability
For correct operation the switchgear availability
and availability of the embedded generation plant should be coordinated.
To maximise the maintenance regime of network switchgear plant
and embedded generation plant will need to be reviewed to ensure
that they are being maintained in accordance with the manufacturers'
instructions. For example number of switchgear operations when
connected to embedded generation might increase dependant upon
the time cycle the embedded generation is connected to the network.
A change from traditional time based maintenance to condition
based maintenance could be considered as a means of minimising
the number of outages required due to carrying out intrusive time
based maintenance work. Condition monitoring procedures provides
the users with indications when maintenance is required based
on the condition of key switchgear components. This is especially
of benefit for un-manned substations.
6.4 Back up Connections
Dependant upon the location of the embedded
generation its importance to the support of the network decisions
needs to be taken. Duplicate connections onto existing network
may be required. This could have an impact on the decision of
the connection layout and suitability of existing switchgear.
6.5 Synchronisation of Embedded Generation onto
the Network
Switching generation onto a network will involve
synchronising procedures. If this is carried out via the network
circuit breakers, they will need to be verified by the manufacturers
whether the switchgear is suitable and rated for out of phase
duty. This could present a problem where old switchgear is to
be used for the connection, leading to a decision to replace with
new switchgear.
6.6 Spares and Manufacturing Support
Increased amount of embedded generation onto
the network would need some careful consideration into spares
and emergency work procedures in order to minimise the unavailability
of embedded generation in the event of switchgear failure.
With the different numbers of generation companies
owning and operating the embedded generation sites throughout
the UK, it might be conceivable for these companies and the DNO's
to share a common spares holding comprising both consumable and
strategic spares. This could be some form of a "spares club".
Manufacturers could be part or even run this shared club, their
input being supplying the spares, providing technical support
as well as site activity support.
6.7 Summary
The key to an optimised high level of embedded
generation into the network is for the end users, network owners
and equipment manufacturers to pool their expertise and review
all aspects of embedded generation in terms of the operation,
network and switchgear equipment.
7. What are the estimated costs of upgrading
our electricity networks, and how will these be met?
No comments available
8. How can the regulatory framework
ensure adequate network investment in light of the current credit
crunch and recession?
8.1 Change of policy to enable the unbundling
of network ownerships to allow new players to own and/or operate
new electricity network infrastructures.
8.2 Mitigate risks by providing tax benefits
to the new players, for first few years of the investment.
8.3 Match duration of legislation to duration
of return of capital for asset investment.
8.4 Technology specific incentives based on
technological maturity.
8.5 Increase transparency to enable informed
investments
9. How can the regulatory framework
encourage network operators to innovate, and what is the potential
of smart grid technologies?
9.1 Reduce penalties and/or increase incentives
to encourage new/novel technologies to be embraced and implemented.
9.2 From incentives to "obligation"
to devote money to R&D
9.3 SmartGrid technologies enable:
— Efficiently operated (and reliable) networks
— Differentiated Power Quality at connection
point
— Faster response to network disturbances
— Self diagnostic, self healing & self
re-dispatch capabilities, therefore reduced interruptions and
minutes lost
— Integration of (potentially) millions
of small scale generators
— Bulk power and small scale sustainability
to coexist
— Demand and supply balance solutions
— Customers to be part of the electrical
power supply system:
— Both producer and consumer of electricity
= "prosumer"
— Real-time price information (smart meters)
— Automated and embedded systems (DR/DSM)
— Adequate investment and reward incentives
— Mature markets and regulation
10. Is there sufficient investment in
R&D and innovation for transmission and distribution technologies?
10.1 The magnitude of R&D investments
into T&D, especially from public funds should be reviewed:
— In comparison to generation technologies,
R&D investments into the "upstream network" have
been lagging.
— Size and duration of individual projects
need careful attention. Innovation in T&D is comparatively
slow and complex. Use of R&D money can be improved by allocating
R&D money to larger projects. This requires:
— The encouragement of alliances and larger
consortia (with special attention to the inclusion of industrial
partners)
— Special encouragement of long term and
durable R&D efforts, more emphasis on long term exploitation
of results
— Dissemination of R&D results should
also be included as an integral part of the overall investments.
This increases the leverage with respect to the money invested.
10.2 Beyond investments into R&D, a regulatory
framework for R&D is required. This includes three aspects:
— DNOs and TSOs should be allowed, and
rewarded, to use revenues for R&D. The reward seems at the
moment too low, such that DSOs appear not to use the full extent
of the IFI scheme. In this situation, the regulator could take
these funds and redistribute them to those who are able to use
them, including relevant industrial companies.
— Innovation also impacts upon regulation.
Experience has demonstrated that some R&D project ideas have
never been proposed because they were in contradiction with current
regulation. To permit the investigation of innovative schemes,
solutions and technologies, the possibility to grant exceptions
to the regulatory framework should be included in the R&D
support schemes.
— A closely related issue is "loss
of revenue" incurred in demonstration based innovation and
research projects. These appear to be a barrier in some cases.
Allowing Generators, TSOs and DNOs to compensate their losses
to a larger extent would increase the R&D activity.
10.3 Technical consortia involving all parties,
end users, network operators and manufacturers should be formed
to explore and share the respective technologies of each. In this
way new innovative technologies can evolve towards optimising
the technical solutions of embedded generation schemes.
10.4 The benefit of this would be for each party
to be familiar with the whole picture rather than with their own
scope of responsibility, this should aid the generation of innovative
ideas and in doing so speed up the R&D solution to market
time.
11. What can the UK learn from the experience
of other countries' management of their electricity networks?
11.1 Early adopters of electronic meters: Italy
11.2 High proportions of renewables: Denmark,
Germany, Portugal
11.3 EDF (France) is committed to enhance its
efficiency and responsiveness under the cases of major disturbances,
and to improve the overall performance of the network. Several
plans have been then implemented:
— Climatic area plan so as to reduce the
sensitivity of the grid to the climatic risks (ice, storm, flood,
heat wave)
— Fast mobilizing plan for emergency
— Daily load shedding exercises
— Restoration of the power supply of critical
sites in 12 hours
— Restoration of the supply in less than
five days to 90% of the consumers under the exceptional circumstances
of a major climatic disaster (ref. wind storm of 1999)
March 2009
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