Smarter Grid Solutions' poster session contribution for the IEEE Innovative Smart Grid Technologies Europe conference, Copenhagen, October 2013. Mike Dolan, Product Development Engineer, discusses the benefits of Active Network Management on the Shetland Islands as part of the Northern Isles New Energy Solutions (NINES) project. More details are included in a paper published by the ISGT Europe conference. This was written in conjunction with Scottish and Southern Energy Power Distribution, the Institute of Energy and Environment, University of Strathclyde, and Frazer-Nash Consultancy Ltd. Title: Active Network Management on Islanded Systems: The Shetland Experience Abstract: The Northern Isles New Energy Solutions (NINES) project is addressing the energy needs of the Shetland Isles by demonstrating the integration of low-carbon energy sources using smart grid technology. In so doing, NINES represents a major step towards a low-carbon future for Shetland whilst leading and informing the UK-wide transition. The principal objective is to accommodate more renewable connections in an area that has some of the richest renewable energy resources in Europe but is restricted by existing network infrastructure. This paper discusses the role of modelling in establishing constraint rules and the use of those rules in an Active Network Management (ANM) scheme on Shetland. The constraint rules are modelled in offline analysis to calculate the impact of the ANM scheme on the network access of potential customers and to model the dynamic response of the network. The rules are then implemented in the ANM software to manage the output of ANM-controlled generation in real time.

1. Active Network Management on Islanded
Systems: The Shetland Experience
B. O’Neill1, C. Foote2, R. MacDonald2, M. J Dolan2, S. Gill3, G. Milne4, S. Reid4
1 Frazer-Nash Consultancy Limited
2 Smarter Grid Solutions
3 Institute for Energy and Environment, University of Strathclyde
4 Scottish and Southern Energy Power Distribution
Project Summary
The Northern Isles New Energy Solutions (NINES) project is addressing
the energy needs of the Shetland Isles by demonstrating the integration
of low-carbon energy sources using smart grid technology. NINES
represents a major step towards a low-carbon future for Shetland whilst
leading and informing the UK-wide transition. The principal objective is
to accommodate more renewable connections in an area that has some
of the richest renewable energy resources in Europe but is restricted by
existing network infrastructure: The project is trialling a set of new
technologies and solutions including actively managed generation and
frequency responsive demand. The key objectives are to:
• Allow the maximum possible volume of renewable generation to be
connected and reduce fossil fuel consumption.
• Reduce the difference between minimum and maximum daily net
demand on Lerwick Power Station (LPS), enabling more efficient
dispatch of generator sets, and informing the design of a future
replacement power station.
• Enable the provision of ancillary services from a wider range of
customers on Shetland.
Conclusions and Future Work
• ANM can facilitate the connection of new generation to a network that was previously
considered to have no spare capacity
• ANM can be used to manage stability or other constraints, extending the scope of ANM-
based control beyond power flow and voltage constraint management
• The project serves as an example of what might be achieved in other networks to
overcome constraints that are slowing or restricting the transition to a lower-carbon
electricity system
• Future work will include refinement of the constraint management rules
© 2013 Smarter Grid Solutions Ltd. & Scottish and Southern Energy
Network Constraints
• Network Operation
• Frequency Stability
• Spinning Reserve
Where:
𝐿 𝑆ℎ𝑒𝑡𝑙𝑎𝑛𝑑
is total Shetland demand (MW)
𝑃 𝑀𝑎𝑟𝑔𝑖𝑛
is a safety margin (MW)
𝑓0 𝑓𝑖𝑥𝑒𝑑 𝐷𝑒𝑚𝑎𝑛𝑑 is an upper stability limit on wind power output
23 is the export limit from SVT (MW)
All other ‘P’ values are power exports from conventional and wind power plants
𝑃𝐹𝑆𝐶 = 𝑓0 𝑓𝑖𝑥𝑒𝑑 𝐷𝑒𝑚𝑎𝑛𝑑 − 𝑃 𝐵𝑢𝑟𝑟𝑎𝑑𝑎𝑙𝑒
− 𝑃 𝑆𝑚𝑎𝑙𝑙 𝑊𝑖𝑛𝑑
− 𝑃 𝑀𝑎𝑟𝑔𝑖𝑛
𝑃𝑆𝑅𝐶 = 23 − 𝑃 𝑆𝑉𝑇
− 𝑃 𝐵𝑢𝑟𝑟𝑎𝑑𝑎𝑙𝑒
− 𝑃 𝑆𝑚𝑎𝑙𝑙 𝑊𝑖𝑛𝑑
− 𝑃 𝑀𝑎𝑟𝑔𝑖𝑛
Generator
Name
Size
[MW]
Priority
Uncurtailed
Output
[MWh]
Final Curtailed
Output [MWh]
Curtailed
Capacity Factor
[%]
Gen A 2 1 8483.91 6274.81 35.82%
Gen B 2 2 8483.91 5675.24 32.39%
Gen C 2 3 8483.91 4792.94 27.36%
Gen D 2 4 8483.91 3752.59 21.42%
Gen E 2 5 8483.91 2776.00 15.84%
The lowest value from the three constraints
defines the limit on ANM-controlled
generation (ACG) on Shetland:
ACG_limit = min(𝑃 𝑁𝑂𝐶, 𝑃𝐹𝑆𝐶, 𝑃𝑆𝑅𝐶)
Establishing ANM Rules
The process of defining the constraint rules has four steps:
• Defining acceptable operational criteria
• Defining expected operating conditions
• Defining key events against which to secure
• Modelling the Shetland network
Curtailments Assessments
• Constraints determine the available network capacity
• Curtailment assessments use time series modelling
• Assess the impact of different constraints under varying network conditions
• Each time step the projected output of all generators is summed
• When ANM-controlled generation exceeds the ACG limit it is curtailed
0
2
4
6
8
10
12
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41
MW
Time Period
ACG
Release
Trim
𝑃 𝑁𝑂𝐶 = (0.6 ∗ 𝐿 𝑆ℎ𝑒𝑡𝑙𝑎𝑛𝑑
) − 𝑃 𝑆𝑉𝑇
− 𝑃 𝐵𝑢𝑟𝑟𝑎𝑑𝑎𝑙𝑒
− 𝑃 𝑆𝑚𝑎𝑙𝑙 𝑊𝑖𝑛𝑑
− 𝑃 𝑀𝑎𝑟𝑔𝑖𝑛
Stable
Envelope for
Wind
Generation
Figure 1: Shetland Island Location and 33 kV Network
Figure 2: ACG Limit as System Load Increases
Table 1: Example Output from a Curtailment Assessment
Prospective developers can use the outputs to estimate
the commercial viability of their developments
Figure 3: Illustration of ANM Controlled Generation