For many years, grid operators relied only on tried and tested technologies – but a drive towards innovation in recent years is reaping rewards. Peter Jones explains how new technologies and new applications for existing technologies can help operators make the most of their assets and do more with less
The UK is at the forefront of innovation in power grids. The World Energy Council has awarded us a rating of AAA for balancing the three priorities of energy security, affordability and environmental sustainability that form the energy trilemma. Of these, affordability is most often in the spotlight, with the government currently considering a bill to cap energy prices. Pressure is also being applied indirectly, for example from passengers reacting to the announcement in August about rail fare rises. The pressure means that it’s worth thinking about ways to achieve targets with less budget and without impacting quality.
Ofgem’s Network Innovation Competition (NIC) funding mechanism is a great demonstration of how the government is incentivising the industry. Two examples of projects funded through the NIC scheme were the PowerFul-CB and Phoenix projects. Under PowerFul-CB, ABB will introduce power electronic circuit breaking technology to help UK Power Networks address fault currents in London as the distributed generation and combined heat and power schemes are introduced.
During the Phoenix project, ABB will deliver a world-first hybrid synchronous converter (H-SC) for ScottishPower. The H-SC integrates two existing technologies: a power electronic static compensator (STATCOM); and a conventional synchronous converter. The H-SC will be deployed to provide dynamic voltage control as the UK’s coal power stations go offline.
Momentum inside the large rotating generators has inertia that keeps the turbines spinning for a long time even when unpowered. As coal plants are decommissioned, this is coming offline and renewable energy has little or no inertia to keep grid voltage and frequency stable. However, many operators adopt innovative approaches outside the scope of Ofgem’s funding programme.
Saving 60 % of grid connection cost
For example, Network Rail has adopted a Static Frequency Converter (SFC) to upgrade the power supply on the East Coast Main Line in preparation for new bi-mode dieselelectric trains that will begin service in 2018. To run on electricity through Doncaster, the new trains will draw around three times more power than is available on Network Rail’s existing supply. The conventional solution is to construct a new high-voltage grid connection – but this is costly and has a long lead time.
Instead, Network Rail opted for an SFC to adapt the three-phase feed from Northern Powergrid’s distribution network and convert it to a single-phase 25 kV trackside supply. The SFC has an estimated total cost saving of 60 percent compared with building a new grid connection. The technology is already well established in shore-to-ship power connections and also by Queensland Rail in Australia.
Other innovations can piggy-back on existing services and ABB’s high voltage transformer service team regularly adds value this way. In 2015 it took the opportunity to integrate the UK’s first real-time online monitoring through Transformer Intelligence while remanufacturing a 135 MVA generator transformer for Lynemouth Power Station. Another example was a de-tanking service of a transformer for cement manufacturer Cemex. De-tanking is usually undertaken at ABB’s specialist facility in Norway but in this case, de-tanking in the UK enabled close inspection of the windings to give confidence that the transformer could be repaired within a few months – saving the 12-month lead time and cost of a new unit.
Passing into normal practice
Projects to deliver new-to-the-UK products or services are often the subject of much focus. However, after the initial fanfare, they can become common. Adoption of PASS (plug and switch system) illustrates this. The compact hybrid switchgear combines all functions into a single switchgear module, therefore enabling a compact footprint. These include circuit breaker, combined disconnecting and earthing switches, current transformers and fast-acting earth switch.
It was first used in the UK by Scottish & Southern Energy (SSE) at its Reading substation in 2008. When delivering a new GIS (gas-insulated switchgear) substation on the densely populated site, adopting two PASS M0 units saved enough space to dismantle old switchgear bays and make way for a new substation building without losing any circuits during construction.
Many operators have since adopted other types of PASS unit since then, particularly when looking to achieve a cost-effective and compact substation – which the switchgear achieves by combining air insulated and gas-insulated elements in a single unit. In 2014, Northern Powergrid adopted PASS M00 units at its Cramlington substation to replace existing time-served 66 kV bus section circuit breakers.
Freedom Group ordered the UK’s first PASS M0H unit, a version of the switchgear that takes the form of an H-configured switchgear bay. Freedom Group specified the PASSM0H for a 10 MW data centre, where it delivers a 2N level of security through connecting to two separate incoming 132 kV transmission feeds. Today, PASS units are used regularly across the UK’s distribution networks.
Another innovation approach that we believe will be the first of many is the protection and control scheme that ABB is delivering for Network Rail for the Great Western Electrification Programme. The sophisticated substations communications and control concept has allowed Network Rail to reduce the number of circuit breakers required and replace them with less costly load break switches.
Circuit breakers can tolerate and break a high fault current, whereas load break switches cannot. Recognising this, Network Rail’s engineers devised a tailored approach to IEC 61850 smart grid communication called the Rationalised Autotransformer Scheme (RATS) scheme. This uses intelligent electronic devices (IEDs) to ensure that circuit breakers will open in the case of a fault, preventing the load break switches from ever experiencing a fault current.
The key to delivering RATS has been ABB’s IEC 61850 communication equipment and an extensive programme of simulation and bench testing at ABB’s system verification facility in Stone, Staffordshire. This has enabled ABB to deliver its protection and control equipment inside self-contained auxiliary equipment enclosures that arrive on site ready to plug and play. Once in operation, faults can be detected, isolated and supply resumed within six seconds without any manual intervention by a human operator.
Peter Jones is technology strategy manager for ABB Power Grids