What is the Smart Grid, really?

Richard Ord, Amantys


Definitions of the "Smart Grid" range from highly technical descriptions to purely commercial interpretations

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Figure 1: Escalating installations of renewable energy sources are likely to be distributed far and wide

The Smart Grid - a changing landscape of supply, demand and storage Definitions of the "Smart Grid" range from highly technical descriptions to purely commercial interpretations, but whichever one you may follow, it implies a major re-engineering of all aspects of infrastructure, usage pattern and business models across the whole electricity supply industry. As a result, the management of the network is one of the biggest challenges facing suppliers and one significant challenge is how to observe effectively how each cell and part of the network is performing, placing network sensing and communications at the center of innovation. From central to distributed generation The distributed nature of the Smart Grid sets it apart from the historical unidirectional flow of power, where nuclear or fossil fuel power stations of up to 3GW generated power to distribute outwards through the grid. The very name of the UK's former nationalized generating body of the day gives the clue to the system structure - the Central Electricity Generating Board, or CEGB. Those power plants were typically based in low population areas or close to the fuel supply resource. Escalating installations of renewable energy sources are also likely to be distributed far and wide - whether onshore or offshore - and these too will typically be a long way from the existing grid infrastructure (see Figure 1). Key differences There are a number of key differences between a smart grid and the more traditional ‘national grid' approach, affecting all aspects of generation, transmission, storage and consumption, and with a bidirectional flow of energy throughout according to local and national variations of supply and demand. A smart grid may also include features such as digital sensing, control and communications across the entire network and a ‘cellular' type structure of regional grids. A modern cell within the smart grid will include industrial and consumer energy consumption, as well as renewable energy generation from wind and solar energy sources. These sources may themselves be under industry, government or private ownership. Even at the smallest level, any factory site, business premises or private household could be drawing power from the grid or supplying energy into it at different times of day or night. As a result the smart grid network isn't predictable, demand can vary depending on weather conditions, and supply may come from different sources at completely different times each day. Changing dynamics of power switching The implications at the level of power switching are enormous: as well as the need to monitor supply and demand at a micro level, the intersection of power transmission between each cell will need a level of robustness and reliability not previously engendered in the national grid. A power station ready to boost output at the half-time break in national sports events will no longer suffice. The need for resilience and robustness Homeowners with their own solar panels perhaps represent the smallest unit of power ebb and flow, drawing from or feeding back into the grid. Offshore wind farms face a similar challenge, dealing with wide day-to-day variations of power generation, and the management of how this is fed into the grid. At a national or macro-geographic level, there are already links between grids, whether across the English Channel, between different European countries, or across North America and China. At each of these junction points, energy flow is bi-directional, but the imperative is that failure or instability in one region cannot propagate into the other and shut down the neighboring region. This same imperative will also apply at the cell boundaries in the Smart Grid, demanding power switching systems that can isolate neighboring areas from varying energy flow and frequencies. Digital techniques at the core of the switching system At each of these stages, the level of performance monitoring available is still what we'd expect from the older national grid. When the network becomes much more complex, there's a clear demand for real-time observability at every level from the power switch to the national grid. In Germany there have been documented challenges in managing the supply generated though solar and this reinforces the need for something new. Whether that's in a warehouse hundreds of miles away from the nearest engineer or at a more local level, using digital techniques to monitor power switching can make smart grids much more manageable. Visibility across the network New monitoring systems will satisfy the need at a higher level of operational performance, but such systems will be better informed if information is available right from the power switch. The operator can then assess real-time data in light of changing power stack performance, environmental conditions and as critical components age. This performance intelligence helps to build a profile of how the system operates and reacts in different conditions, and this can then be rolled back into new developments and installations, reducing test time and cost. When there are faults or failures, current systems flag a failure but without context of what happened or the conditions leading up to the failure. Understanding what causes faults and failures is essential in improving the efficiency and the resilience of the smart grid. Getting renewable energy back into the grid Getting power back from the offshore wind farms or remote areas presents another challenge in power switching and it's here where HVDC (High Voltage DC) has proven to be more efficient and less expensive than AC transmission when these links are underground, underwater, or across hundreds of miles over-ground. A typical modern HVDC switching hall will be populated with rack after rack of power stacks, each comprising dozens of IGBT modules mounted on a cooling plate, and filling the space of a medium-sized warehouse. Yet this move presents another set of challenges, with a facility including tens of thousands of high power IGBT modules, each with a gate driver circuit, and, until now, the switching signals available from these modules was limited to on, off or fault. In a facility such as this, once the system is powered up, the operator won't want to open the doors for many months or even years, so any techniques that can help provide performance monitoring from within the switch to the outside control domain is welcome. This is particularly important when the facility is likely to be miles away from the nearest engineer; spotting faults early is critical to maintaining reliability.

Intelligence in Smart Grids At Amantys our approach is all about intelligent monitoring of power switching and understanding more than just a simple on/off/fault reading from each IGBT. Amantys Power Insight provides a hardware and software infrastructure to observe and monitor power switching from its foundation, providing the basis for a robust and resilient system. By integrating intelligence with an ARM Cortex® M3 processor at the core of the system, the operator can program and modify the flow of data from the switch as a function of performance and environment in real-time (see Figure 2). Smart Grid and the "internet of things" In the Smart Grid the biggest challenge is still managing and balancing the network. It seems almost backward that while techniques for generating and transmitting power may have changed, the level of insight into its performance and reasons behind faults and failures is lagging far behind. For the Smart Grid to be truly smart, understanding how it's working at its very core is essential to improve the efficiency and resilience of the system. Amantys