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NETWORK / 16 / July/augusT 2017 Flexibility has become an increas- ingly critical aspect of network operations across the board. From the remote regions of the scottish islands to the big cities, networks are under increasing pressure to adapt to the rapidly changing mix of generation and storage technologies. synchro- nous generation is falling away to be replaced by distributed and intermittent technologies. This brings challenges to ensure there is enough capac- ity to meet demand. But it also challenges networks to ensure greater flexibility of operations to keep the power coming, even when infrastructure maintenance must be carried out. One area that is receiving increasing interest from networks and original equipment manu- facturers is the development and use of mobile substations or packaged control rooms as an effective way to ensure operations continue during maintenance and repair works, and also to offer the opportunity to connect new generation assets more quickly. Having been used for a num- ber of years at lower voltages, typically up to 145kV, to provide backup for existing infrastruc- ture, investment and develop- ment of higher-voltage systems to support and operate transmis- sion systems has increased in recent years. National grid outlined the potential benefits of a high-pow- ered mobile substation unit in an unsuccessful Network Innovation Competition submission in 2014: "The expectation is that it will significantly reduce construc- tion timescales for temporary capacity, enabling more flexible and efficient capital delivery and maintenance." Among the benefits that the project team envisioned mobile substations would bring were: freeing up outages or removing constraints, quickly providing temporary capacity to manage changes in network conditions, and positively benefitting custom- ers by connecting renewable generation sooner. although the submission on that occasion was unsuccessful, National grid and the DNOs are continuing to explore new ways to use and work with mobile substa- tions and mobile generation to alleviate some of the challenges brought on by the changes to the network landscape. For leigh Turley, engineering manager of transmission and distribution at aBB, the key to its appeal lies in its speed and the stability it offers: "Really, it's something that can be installed very quickly, that is repeatable and will add security and flexibility to the network. It reduces risk to the client and end user." In particular, there are two main aspects of operations where the technology has the greatest potential. The first is in outage management planning, where the units are rolled out and installed to provide temporary power when planned maintenance work on ex- isting assets is required, removing the need for any loss in power as a result of the works. The second area is dur- ing unplanned outages as an emergency replacement for a transformer, circuit or feeder that has suffered a fault. In such a case the mobile substation is installed and enables power to be quickly restored. But according to Turley, mobile substations hold even greater at present, because of the increas- ing need to connect distributed generation more quickly. "If you're doing a connection for a distribu- tion operator, they've historically not been turned around very fast. "For instance, somebody could build a solar farm or wind farm, and if the main substation hadn't been built, you could connect it to the overhead lines via a mobile substation, as a temporary meas- ure," explains Turley. "That stops you having to wait for planning consent and also means that if the power plant has been built earlier, you can start getting rev- enue from the system, so again, it reduces risk for all involved." In addition, he also sees it opening up the opportunity for networks to sweat assets longer, with the deployment of mobile substations, enabling improved maintenance schedules to maximise the operational life of existing and ageing assets. In terms of capitalising on these opportunities, Turley is adamant that the technologies are available and, as they develop, continue to get smaller and easier to deploy. However, in terms of maximising their potential, he suggests the more critical ele- ment is on a human and organi- sational front. Doing things differently He says: "The technology is one aspect of it, but the critical part is adapting and modifying your systems and your processes to work with the technology to allow yourself to do things differently." He adds that success will require a balance of "out of the box" think- ing and operational experience. Overall, he envisages a bright future for the technology, and believes it will fit neatly into the emerging demands being placed on networks: "There's a thirst to do things differently, a step change within our industry. People are thinking how can they influence the network by not just adding more bits of plant and more assets. so can we sweat assets a bit further if we maintain them a bit more – and if we do that, how do we reduce the impact of the outages required?" For Professor Phil Taylor, director of the EPsRC National M o b i l e S u b S tat i o n S A mobile substation can help during system maintenance and unplanned outages, or even help renewables developers connect their schemes to the network more quickly. A pair of 380kV Siemens mobile substations are to increase the resilience of the Saudi Arabian power grid