How come the lights don’t go out more often? Keith Bell discusses the challenges facing the UK power system.

Keith Bell, the Scottish Power Professor of Smart Grids at Strathclyde University visited the UCL Energy Institute at the end of January to give a talk about the risks and challenges facing the UK power system and the role of smart grids in responding to them.

 

The starting point for his talk was the annual cycle of concerns about system capacity with autumn being the regular season for press stories about the possibility that the UK might not be able to ensure that we have enough electricity to keep the lights on all winter.

It is an understandable concern given our reliance on electricity but as Keith pointed out the UK’s target of 3% more supply capacity than the peak demand is calculated based on peak demand on the peak day. So for much of the time, the excess supply capacity is greater.

Capacity does vary and modelling suggests that there could be 5 hours in the year in 2015-2016 during which there is not enough power to meet demand. However, if electricity demand is greater than supply there are a number of options the network operator can use before having to cut off supply:
• Reduce or remove supply to large industrial customers who have entered an agreement to allow this to happen in return for a financial incentive
• Operate the generating plant beyond its recommended operating standards for a short time
• Reduce the voltage

Energy storage is expensive and capacity is small so a better option is to try to time power generation for when it is needed.  Which means there really is someone whose job it is to watch TV in the National Grid control room and make sure that more plants are brought on at half-time in the world cup.

In reality, though, plant failure is a bigger issue than everyone switching their kettle on when the half-time whistle blows.  In particular, the complexities of interconnections mean that problems have occurred when more than one outage happens at the same time.  In some cases, protection mechanisms designed to protect assets have contributed to a cascade of failures across the network.  For example, in 1996, a system failure affected 7.5 million people in Western USA for up to 9 hours and another incident affected 20 -25 million people in Central Europe in 2006.  However, these remain the exception and normal operation is generally resumed quickly: in the 2006 incident, normal operation was resumed in 2 hours.

With only 2 double failure incidents per year in the UK, problems in the high voltage transmission network are rare.  Although, on average, the UK suffers 80 interruptions per 100 customers per year, this is mainly due to problems in the 300,000 km distribution network and generally only affects small areas.  It seems likely   that increasing adverse weather events as a result of climate change will lead to more problems with the distribution network.  But with distribution and transmission costs averaging 20% of a household’s electricity bill already, it is not clear that consumers will be willing to pay to increase reliability, nor that this would be cost effective.

It has been suggested that smart grids could provide some of the answer.  Smart grids are intended to   promote the reliability of supply and the decarbonisation of the grid, partly through supporting the electrification of heat and transport. However,  smart grids bring their own challenges. 

The huge explosion in the number of active elements and data means that communications present a new risk.  The smart part is in the design of the decision support tools and automation processes to manage demand. However, getting these right is difficult. For one thing,  the funding mechanisms must be right to create the incentives for innovation.  Increasing automation also increases the risk of communication faults and this is already the single greatest cause of system issues.

Overall the greatest challenge facing the UK power network is maintaining the necessary levels of knowledge and organisation in the industry, both in terms of ensuring sufficient numbers of graduates are entering the industry and in ensuring a degree of overarching co-ordination.

Keith concluded that there was no evidence that problems were as bad as some of the press scare stories. However, he also pointed out that power systems are large, complex systems and many  uncertainties are introduced by market conditions and new technologies. There is therefore a pressing need to ensure sufficient skills within the power industry to manage the uncertainties.