Orkney Smart Grid - Relieving grid congestion and connecting more renewables by managing power flows and estimating real-time thermal ratings.
The Orkney Islands smart grid has added >20MW capacity for
renewable generation and saved £30 million, demonstrating how
Smarter Grid Solutions' Active Network Management
technology can relieve grid congestion by creating additional
capacity in the existing electricity grid.
"Smarter Grid Solutions' technology has the potential to
significantly improve the efficiency of the electricity
distribution network in the UK. The Orkney network is a blueprint
for how power companies can use sm
art grids to connect high levels of renewable generation
cost effectively to resolve grid congestion.
The total cost of developing and delivering this innovative
technical solution was less than £500K. If we had tried to connect
similar levels of renewable generation by reinforcing our network
in the conventional way, it would have cost around £30 million, and
taken considerably longer."
Colin Hood
Chief Operating Officer, Scottish and Southern Energy Power
Distribution
The challenge
The Orkney Isles have unrivalled access to wave and tidal power,
together with one of the highest wind capacity factors in Europe.
Orkney was also quick to respond to the Government's Renewable
Obligations, which said that communities needed to meet more of
their power need
s from renewables. From 2002 onwards, there was an influx of
applications to connect new wind generators of varying sizes to
Orkney's electricity grid.
Scottish and Southern Energy Power Distribution (SSEPD), who
owns and operates Orkney's electricity grid, needed to find a
quicker, more cost effective and greener way to provide customers
with grid connections than taking the traditional route of
expensive upgrades to the grid infrastructure. It also wanted to
ensure that security or quality of supply were not compromised, and
to support Orkney's renewables projects by enabling appropriate
commercial arrangements for multiple new generators on the
Isles.
Our approach
The Orkney electricity network is served by two 33 kV
circuits connected to the Scottish mainland. The existing
generation at the outset of the project already included 21 MW
of capacity that would be disconnected or 'intertripped' in the
event of an outage on one of the circuits to the mainland.
According to conventional electricity grid planning standards the
Orkney grid was 'full' and unable to accommodate any additional
generator capacity for further wind farm and other renewable
generator projects. At this stage, Orkney was already exporting
power at times of high renewable generator output.
The starting poin
t for our solution was that in real time the grid had spare
capacity due to the inevitable fluctuations in electricity demand
and in output from different generators. The aim was to investigate
how to better exploit and quantify this latent capacity.
The outcome was new smart grid technology that allows greater
numbers of renewable generators to connect to the existing grid by
better exploiting the latent capacity available.
This Active Network Management
(ANM) technology allows generators to access capacity not
normally available under conventional grid planning. It does this
by monitoring and regulating various characteristics of the grid in
real time, and maximising the real-time output of new renewable
generators within the prevailing constraints of the grid.
sgs power flow
In November 2009 Smarter Grid Solutions installed our sgs power
flow application on sgs core, our smart grid
control platform, to enable SSEPD to connect multiple new renewable
generators to the constrained network on Orkney.
sgs power flow
works in zones and regulates the real-time output of participating
generators, demand or storage devices, at multiple locations on the
network. On Orkney, it varies power production of p
articipating generators between zero and full-rated power to
manage grid capacity constraints.
sgs power flow
includes fail-safe mechanisms to mitigate and minimise the risks to
the grid caused by generators not following issued set points,
outages on the grid and loss of communications between ANM components.
On Orkney, sgs core is
deployed with our sgs comms hub platform.
sgs comms hub
performs all data handling and processing for the ANM scheme and is fully
integrated with SSEPD's Supervisory Control And Data Acquisition
(SCADA) system to give the network control room an overview of how
sgs power
flow is working.
Despite its integration with the SCADA system on Orkney, the
solution is autonomous. It performs and implements control actions
without manual intervention and does not depend on SCADA, or any
other central system, to operate. sgs
core and sgs comms
hub can be installed at any suitable
location such as substation, control centre or data centre.
SSEPD has set up a pioneering commercial arrangement for
electricity distribution networks on Orkney. Each new generator
accepts a constrained connection based on its position within a
'priority stack'. So they are given access to grid capacity
according to an agreed order of merit.
sgs power flow is scalable and flexible so, as
demonstrated on Orkney, it can incorporate new generators and
changes to the grid over time.
sgs ratings
In early 2011, Smarter Grid Solutions worked with SSEPD to
upgrade the Orkney smart grid by installing the PowerDonut2 , a
dynamic line ratings device (DLR) that measures the temperature of
overhead conductors. We also installed our real-time thermal
ratings application, sgs ratings, to work
alongside the DLR and provide estimates of the real-time rating in
circuit spans without a DLR device i
nstalled.
sgs ratings
estimates ratings over a wide area of the electricity grid. It uses
meteorological stations and considers all the available information
about meteorological parameters, conductor temperature and
communications state, to estimate a safe and persistent value.
This provides a far more accurate real-time assessment of the
thermal constraints of the power system compared to the
conventional static seasonal ratings method, which is based on the
maximum operating temperature possible over a continuous period and
depends on how the power line dissipates heat to its surroundings.
It is also affected by environmental factors such as wind, air
temperature and solar radiation.
Using sgs ratings
together with sgs power
flow has offered several advantages
over conventional DLR for the Orkney grid. It has:
- minimised the number of DLR devices we need to install on the
grid
- been more resilient to measurement and communication
failures
- produced forecast ratings and estimates that apply for a longer
period.
The benefits
In November 2009, two new wind generators were connected to the
electricity grid. Another wind farm followed in 2010 - and today
there are a further five new renewable generators connected to
Orkney based on the smart grid technology.
The smart grid has stimulated a number of new renewables
projects, many community owned, that otherwise would have struggled
to gain access to the grid. This growth of activity in the local
economy has encouraged increasing numbers of community bodies,
development trusts and co-operatives to put forward new
projects.
The Orkney Smart Grid has also created global knowledge and
learning for future smart grid projects.
The business case
The business case for using real-time smart grid technology to
overcome grid congestion and connect high penetrations of renewable
generation is clear.
SSEPD has invested in the region of £500,000 in the Orkney Smart
Grid, which has so far released >20 MW of additional
capacity in the existing grid to connect new renewable generators.
This has paved the way for an estimated £25 million of investment
in community wind turbines and private sector-sponsored
initiatives. These schemes have generated significant
benefits for the local economy, including new community facilities
and additional ferry services between the islands. The Smart Grid
has also created a platform for us to trial future smart grid
developments.
To connect similar levels of renewable generation on Orkney by
conventional investment in grid upgrades would have cost around £30
million - 60 times more than the cost of the smart grid - and would
have taken considerably longer.
Furthermore, paying a share of these upgrade costs would have
been prohibitively expensive for generator developers, particularly
those with smaller projects.
As a result of introducing sgs
ratings, SSEPD expects to increase the output
of its generators by a further 48% and allow the connection of 20%
more renewable generation.
For more information please visit SSEPD here.
For other power companies and utilities wishing to relieve grid
congestion, Orkney is a real-life case study of how to deliver
financeable new generator connections to customers keen to exploit
their renewables output.