à‚ While the power industry and energy regulator Ofgem work on the definition of the Smart Grid and begin to lay down plans for its implementation, the UK energy gap continues to widen. Here, James Turner of Schneider Electric explains how existing technologies can help generators, distributors and users make the most of the available energy supply.à‚
Underlying any development in the power generation industry today in the UK ” indeed globally ” is the drive towards a low-carbon economy. Reducing carbon dioxide emissions on environmental grounds is the key principle behind all considerations of how we will generate, distribute and consume power in the future.
Not to be forgotten, however, are the economic drivers for increased energy efficiency from a cost-saving perspective. From both angles, we need to get more from the current power generation infrastructure, as well as to invest in new technologies.
Although the UK has made some progress in consuming power more frugally, the structure of modern society creates, and will continue to create, a hunger for power that the power industry struggles to meet. This hunger is compounded in the short term by the looming closure of old nuclear and fossil fuelled power plant. Unless some tough decisions are taken very soon, much of the UK’s generation capacity will be lost, with unpleasant consequences for its industry and consumers, and for global confidence in its economy.
In the longer term, new nuclear, carbon capture and renewable energies will have a more significant role in the overall energy mix. The European Union (EU) has set a binding target of 20 per cent of its energy from wind and other renewable resources by 2020 and is currently consulting on an increase to 30 per cent.
As we stand at the moment, despite some positive moves from the UK government and the best efforts of suppliers, low-carbon technologies are not yet deployed in sufficient capacity to play a major role in solving the energy supply challenge. So how do we make the most of the generation capacity we have available today?
A Smart Grid Needs A Holistic Approach
The vision for the future is the Smart Grid, an electricity grid with information and communications technology and control mechanisms to integrate the actions of all users connected to it. It envisages the greater adoption of smart metering, electric vehicles, microgeneration and CHP as active participants in the new intelligent network.
The Smart Grid as defined by the Electricity Networks Strategy Group (ENSG) has two key requirements: First, to facilitate the connection and operation of generators of all sizes and technologies; and, second, to enable demand-side management to help optimize the operation of the system.
Solutions for a Smart Grid involve a wide range of technologies and approaches, such as automatic network management, load aggregation, voltage control, dynamic line rating, condition monitoring, demand response, and advanced communications architecture. The initial tranche of proposed distribution network operator (DNO) projects under energy regulator Ofgem’s à‚£500 million ($770 million) Low Carbon Networks Fund are the first co-ordinated moves in the UK to pilot and understand the impact of these solutions on the network.
In its Smart Grid routemap, supporting the UK’s planned low-carbon transition and helping it hit the 2020 target, the ENSG has estimated a CAPEX investment of up to à‚£1.65 billion ($2.5 billion) this decade in substation sensing and control, transformer installation, smart appliances, demand response control equipment and IT, as well as additional communications.
Many of these solutions are already available and can be applied to improve the current network’s performance through optimizing operations, improving power quality and stabilizing supply.
Automatic network management
One such area of focus is automatic network management (ANM), which is the real-time management of distributed generation assets to meet network constraints. Requiring control and communication across the grid and a level of asset integration not seen before, ANM is a good example of the new grid environment with a host of providers working together: DNOs working with wind farm operators to provide network capacity, with electrical infrastructure providers to control assets, with IT firms to communicate data, and with the National Grid to manage impact on the network.
Substation sensing utilizes power meters, RTUs and SCADA to provide condition monitoring and remote switching and control of network nodes. This is an area where the academics of Smart Grid come crashing against reality. While it is clear that a cutting-edge automated substation, perhaps with variable tappings on the transformer for voltage control, would have many Smart Grid benefits, the practical situation is that DNOs have to work with existing legacy infrastructure where transformers are often more than 20 years old.
With perhaps 90 000 distribution transformers in a DNO region, the cost and disruption of upgrading and/or replacing them all with new substations would be untenable. Instead a rolling programme of transformer assessment gives the DNOs a greater understanding of their load index and asset health. As an iterative step towards the Smart Grid, the replacement of end-of-life assets by low-loss transformers gives an immediate improvement in substation performance.
Low-loss transformers require more core and winding materials than ‘standard’ transformers but their running costs are reduced. If a transformer is fairly high loaded (more than 70 per cent), then the savings can be considerable and the pay back period for the transformer can occur within a few years. Each DNO has a unique transformer loss level, based on the topography of its network, and provides manufacturers with capitalization formulas based on its network costs.
Implementing more flexible solutions
Demand energy management is a continual evolution and what we achieve now in energy-saving and energy-efficient technologies will not only instigate behavioural changes but also help pay for further improvements.
With the gap between supply and demand widening, more flexible solutions are required, such as the demand-response or Short Term Operating Reserve (STOR) programme. This is already proving one of the best solutions to provide a reliable and stable supply of electricity back to the grid, whilst protecting users from loss of power.
By entering into the demand-response programme, customers gain revenue and distributors secure advanced notification of grid stress. The programme also safeguards infrastructure as energy will be reduced when voltage fluctuations are likely.
Harmonics and power quality are other areas of growing significance. If renewable power sources such as wind farms are to play the greater role demanded of them, harmonics and network support during periods of variable power output will be key in their integration into the grid. The grid was built for traditional power sources and is not yet fully modified to cope with wind energy. The emphasis is on producers to make sure their power is of the highest quality for secure integration into the existing energy system, which means remaining within the tolerance of the grid code.
|Wind farm solutions architecture|
Harmonics affect power quality as they can disrupt the operation of devices and increase operating costs. Problematic harmonic levels can lead to overheating of transformers, motors, drives and cables, as well as thermal tripping of protective devices and logic faults in digital devices. Active Harmonic Filters (AHFs) provide one of the most effective means to mitigate harmonics, reduce process-related voltage fluctuations, and improve equipment life and system capacity.
An example of this is the Schneider Electric AccuSine PCS, which injects harmonic and reactive current to limit harmonic distortion and can improve the displacement power factor for the electrical distribution system. The resulting reduction in harmonic levels delivers improved network reliability and lower operating costs, eliminates complex harmonic compliance limit calculations and removes nuisance harmonics from the electrical network.
On the road to achieving the ultimate Smart Grid solution, the industry needs to consider both the optimization of existing fossil fuel supplies and the integration of energy from renewable sources.
A 36 kV Schneider switchgear designed for transformer substations in wind farms
Smart Grid is also a bigger issue than just the UK. Greater transmission links with Europe, at the very least, will be needed and, as we achieve more interconnection, the importance of applying information and communications technologies will increase. The Smart Grid can only be achieved by applying sensing, measurement and control devices with two-way communications that make it possibly for the system to respond to changes in grid condition.
Of course, this technology is already partly is situ. But it is now a case of how it is extended down the energy infrastructure. The controls used in today’s network can extend much further than substation level into areas such as lower level monitoring and switching, feeder pillars, LV switchgear, building management systems and renewable interfaces.
But, ultimately, the Smart Grid’s success will depend not on technologies, but on the industry delivering a robust, flexible and scalable grid for generations to come.
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