SMART ENERGY POWER HUB: AN ADVANCED VIRTUAL POWER PLANT HELPING DENMARK AND THE FAROE ISLANDS INTEGRATE WIND POWER By Jonathan Spencer Jones The virtual power plant (VPP) is not a new technology but one whose time has now come, with the moves worldwide to increase renewable energy generation and to smarten the transmission and distribution grids. In concept the VPP is very simple, and basically comprises a central IT hub managing a cluster of distributed generation, storage and flexible consumption resources to deliver services to the various power markets, in much the same way as any traditional power plant and with the same reliability, but with a higher degree of flexibility. The challenge is that the renewable sources, particularly wind, are very variable. For example with wind – the main renewable generation source currently in countries in Europe – the variations can be both on a minutes to hours scale as the winds shifts or a storm stops the wind turbines for a few hours, or it can be days or weeks, as periods of either windy or calm weather can last. This VPP concept underlies the Power Hub, which has been developed by DONG Energy, a European energy group headquartered in Denmark, and is currently being demonstrated in Denmark and the Faroe Islands under the EU’s Twenties initiative. BACKGROUND TO POWER HUB What is the background to Power Hub? Anders Birke, Lead IT Architect at DONG Energy, explains that Denmark is the country with the largest share of wind power – in 2012 wind power covered 30% of the Danish consumption – and consequently is particularly challenged by this. For example, wind power can reach 100% of the consumption and on occasion has even reached 140-150% in the western part of Denmark, and the country needs to be able to manage this. Currently the excess power is exported through strong interconnectors to neighbouring countries Germany, Sweden and Norway. Particularly in Sweden and Norway a lot of the capacity is hydropower, which can be switched off to absorb this excess. Thus, effectively Scandinavian hydro power is able to help balance the Danish power system, keeping the Anders Birke lights on for the 5 million Danes. But if larger countries like Germany or UK installed the same percentage of wind power as Denmark has today, the European power system would be far more challenged, as the hydro capacity would not be sufficient for balancing. On windy days in Denmark the power price can drop to zero due to the excess wind power. Then one might expect the thermal power plants are closed down, but that is not the case, partly because they are delivering stabilizing services to the power system including inertia, reactive power, reserves, etc. This is a costly way to operate the system, as the power price is so low that it would not be able to cover even the fuel costs of the thermal power plants. On top of this Denmark’s policy is to almost double the current wind power capacity to 50% by 2020, so wind power will effectively become the base load of the system and the volatility will be greatly increased. Birke explains the four primary challenges to balancing a future wind-based power system: • Manage the surplus wind and be able to consume the excess power in a valuable way • When there is no wind, to have some back- up capacity or be able to move part of the consumption to other hours • Manage the extreme ramping needs, like when a storm stops a complete wind farm • For the grid – congestion handling, as society becomes more electrified, and voltage control, as wind power can’t deliver as much reactive power and nor can it easily be transported over long distances. Figure 1 – Schematic of Power Hub and the services it can deliver 108 “So we needed to find new ways to manage these challenges, and we see the VPP as a way of delivering services that can help integrate large amounts of wind power in the future low carbon power system.” METERING INTERNATIONAL ISSUE - 3 | 2013