IEEE Power & Energy Magazine - May/June 2017 - 63

deliver up to US$543 million of savings for customers. In
addition, the ability to leverage the existing communication
and control infrastructure demonstrated the practicality and
scalability of this approach, which cost-effectively involves
millions of customers without having any negative impact on
the perceived quality of supply.
However, the major challenge that prevents this smart grid
solution from becoming standard practice for DNOs goes
beyond any technical and economic aspect. Indeed, the main
barrier is the lack of regulation allowing DNOs to participate
in balancing services markets. Two plausible solutions could
be pursued:
✔ create a balancing market specifically designed for
DNOs
✔ require DNOs to provide such balancing service with
a separate compensation mechanism (not in a market)
based on the capital expenditure and operating expenditure required by the deployment of CLASS.
Ultimately, DNOs need to (and need to be allowed to)
embrace a more active and flexible role by controlling their
networks and evolving towards distribution system operators that actively manage their circuits, using CLASS and
other methods.
CLASS is driving this transition, as clearly demonstrated by the U.K. regulator for Gas and Electricity Markets, Ofgem, which decided to extend the CLASS project to
assess the possible economic benefits of nationwide deployment. Based on the positive outcomes of such assessments,
in early 2017, ENWL decided to deploy CLASS to an additional 200+ primary substations, involving a total of over
2 million customers. This represents the first step toward
the discussion needed to define new regulatory and market
frameworks where DNOs can manage and operate their networks jointly with TSOs to address common challenges.
This project also incentivized closer collaboration between TSOs and future DNOs by pushing for novel wholesystem planning and operation of the power system (e.g., the
ICCP link that allows TSOs to access data from and control the assets of a DNO). This will not only accelerate the
deployment of smart grid solutions but will also encourage
the holistic, cost-effective design and management of future
power systems. CLASS played a pioneering role in challenging the way in which DNOs manage and operate their networks by encouraging a more flexible and active role, which
is essential to cope with the challenges of operating a lowcarbon power system.
Although not discussed in this article, the CLASS
project also investigated other potential solutions to defer
investment and help manage the distribution and transmission networks. Demand reduction at peak time can also
be used to release network capacity and hence avoid or
defer substation upgrades (primary or upstream). CLASS
can also be applied to temporarily increase customer demand and provide flexibility that avoids curtailing excess
(renewable) generation. Although controversial, this could
may/june 2017

prove to be a sustainable solution in a market that allows
such a scheme.
CLASS also demonstrated two other interesting techniques. One is the possibility of triggering a much speedier
(seconds) demand reduction by tripping the circuit breakers
of one of the pair of transformers (parallel transformers are
common in U.K. primary substations) based on frequency
measurements. The other is the provision of reactive power
services to the TSO via tap staggering (applicable to parallel
transformers) so as to counteract the effects on voltages from
renewables and/or low levels of demand. These and similar DNO-based solutions ultimately highlight the significant
potential that joint efforts between distribution and transmission can have for the cost-effective operation of future
low carbon power systems.

For Further Reading
Electricity North West. (2017). Customer Load Active System Services (CLASS) project [Online]. Available: http://
www.enwl.co.uk/class
K. Bailey. (2015). Customer Load Active System Services, second tier LCN fund, project closedown report [Online].
Available: http://www.enwl.co.uk/docs/default-source/classdocuments/class-closedown-report.pdf
A. Ballanti and L. F. O. Ballanti. (2015). WP2 Part A:
Final report off-line capability assessment [Online]. Available: http://www.enwl.co.uk/docs/default-source/class-documents/offline-demand-response-capability-assessmentfinal-report.pdf
A. Ballanti, L. F. O. Ballanti, and V. Turnham, "A Monte
Carlo assessment of customers voltage constraints in the
context of CVR schemes," in Proc. 23rd Int. Conf. Electricity Distribution CIRED, Lyon, 2015, pp. 1-5.
E. McKenna and M. Thomson. (2016, Mar.). Highresolution stochastic integrated thermal-electrical domestic demand model. Appl. Energy [Online]. 165, pp.
445-461. Available: http://dx.doi.org/10.1016/j.apenergy
.2015.12.089
L. F. Ochoa, F. Pilo, A. Keane, P. Cuffe, and G. Pisano,
"Embracing an adaptable, flexible posture: Ensuring that
future European distribution networks are ready for more
active roles," IEEE Power Energy Mag., vol. 14, no. 5,
pp. 16-28, Sept./Oct. 2016.

Biographies
Andrea Ballanti is with the University of Manchester, United Kingdom.
Luis (Nando) Ochoa is with the University of Melbourne, Australia, and the University of Manchester, United
Kingdom.
Kieran Bailey is with Electricity North West, United
Kingdom.
Steve Cox is with Electricity North West, United Kingdom.
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http://http:// http://www.enwl.co.uk/class http://www.enwl.co.uk/docs/default-source/class http://www.enwl.co.uk/docs/default-source/class-doc http://dx.doi.org/10.1016/j.apenergy

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