BUILD Q3 2018

46 Build Q3 2018 lectric vehicles are becoming ever more prevalent in the UK, and the energy industry needs to start preparing today. Electric vehicles (EVs) give our industry the opportunity to show consumers just what is possible and will help the UK solidify its rightful place as a leader in the worldwide movement toward clean energy and a sustainable future. This new and exciting energy vector presents a fantastic opportunity, but there are plenty of challenges to overcome before we can move forward. As EV uptake increases, charging infrastructure will need to be available more quickly than many might have anticipated. At such a critical inflection point for the industry, we need to think seriously about solutions to the technical challenges ahead. Without question, distribution system operators (DSOs) are already facing challenges as the result of EVs. Distribution systems throughout the UK are engineered with the expectation that most domestic appliances are only switched on for short durations and not all at the same time, creating system load diversity. This ability to apply diversity factors in calculating load is the reason we are able to connect more than 400 amps per phase of potential load to typical LV feeder circuit. Now, with more and more households having one and sometimes more EVs charging continuously for many consecutive hours, diversity factors decline significantly, whilst simultaneous loads go up proportionately. Without proper planning and system modifications, the ultimate result will be exponential growth in faults and loss of customer supplies. There is little doubt that EVs can create many beneficial impacts on a macro-grid scale. However, there may be problems at the hyper-local/ distribution level due to legacy design issues. The network planning philosophy for most legacy assets installed on secondary networks was based on expectations that there will be cyclic load ratings throughout the day, week, and the annual seasons. This has allowed network engineers to up-rate assets to connect additional loads on the basis that there will be periods within any given cycle (usually 24-hours) when assets will get a thermal reprieve. However, with additional EV loads, the demand curve will flatten nearer to peak load. This means many local distribution assets must be de-rated to comply with their new operating regimes, which consequently means that many of these asset will then be operating outside their new ratings. Bar- ring this, there will be more network faults, leading to increased numbers of customers off supply, and decreased asset lifetimes. Charging must be intelligent and reward the flexibility the consumer gives the network, there is no question. However, this alone will not prevent the eventual need for incredibly extensive secondary network reinforcement. That is, of course, unless an innovative approach to overcoming the reducing asset rating issue can be found. Smart chargers that only allow EVs to draw power when the regional grid is at a state of low load, and when prices are correspondingly low is an- other element that requires more consideration. The only way this system will work without causing distribution network assets to go outside their maximum ratings is for all chargers to have the ability to communicate with all other local chargers on the network and be automatically controlled at a neighbourhood level, in conjunction with the local substation. Clearly, this system would require advanced controls, and the technology, practically speaking, does not readily exist today. Vehicle to grid (V2G) charging could help offset some of the variability in system demands and strengthen potential arguments in favour of a DSO- led supply market. V2G is simply power flow going the other way, which could be beneficial in helping the UK system manage daily generation demand curves from normal domestic and commercial loads. Even though the vast majority of EVs are not currently equipped for V2G usage, this may become the next-generation of EVs. Studies throughout Europe have shown that when V2G is controlled by a “smart grid” algo- rithm, owners see greatly reduced battery degradation in addition to the revenue they realise by sending power back on to the grid. A further question of this “smart” automated approach is whether consum- ers will accept the loss of control over when they charge their vehicles. Of course, they could choose to pay premium rates for charging during peak periods, but the automated controls required to allow this would mean that the DNOs and DSOs would have to be involved in setting dynamic energy prices. The challenge is that current regulation does not allow them to be involved in any pricing schemes, and we should therefore consider amending the current model. There are some significant technical challenges to be overcome when it comes to EVs. Currently, there are too many far-reaching problems that will inhibit the UK’s ability to integrate EVs into its systems and see consumer uptake increase. It is essential that OEMs, EV manufacturers, transmission and distribution network operators and the system operator all participate in a national EV strategy if we are to reach a comprehensive solution. EVs are already a disruptive force. The only question that matters now is what we will do to prepare to enable the carbon free future we all desire. James Crouch is UK Engineering Manager for Burns & McDonnell. To make EVs a success we need to focus on the infrastructure by James D. Crouch E

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