Solar and wind energy may stabilise the power grid

The energy transformation as a supply grid issue: Currently, large central power plants basically supply their immediate surroundings. In future, more small, decentralized wind and solar generators will take on a greater load of the supply. This will lead to a new network architecture that may be less vulnerable to power outages than present-day grids, contrary to the fears of some © designergold, based on outlines provided by the MPI for Dynamics and Self-Organization
The energy transformation as a supply grid issue: Currently, large central power plants basically supply their immediate surroundings. In future, more small, decentralized wind and solar generators will take on a greater load of the supply. This will lead to a new network architecture that may be less vulnerable to power outages than present-day grids, contrary to the fears of some © designergold, based on outlines provided by the MPI for Dynamics and Self-Organization

Renewable energies such as wind, sun and biogas are set to become increasingly important in generating electricity. If increasing numbers of wind turbines and photovoltaic systems feed electrical energy into the grid, it becomes denser – and more distributed. Therefore, instead of a small number of large power plants, it links a larger number of small, decentralized power plants with the washing machines, computers and industrial machinery of consumers. Such a dense power grid, however may not be as vulnerable to power outages as some experts fear. One might assume that it is much harder to synchronize the many generators and machines of consumers, that is, to align them into one shared grid frequency, just as a conductor guides the musicians of an orchestra into synchronous harmony.

In contrast, scientists at the Max Planck Institute for Dynamics and Self-Organization in Göttingen have now discovered in model simulations that consumers and decentralized generators may rather easily self-synchronise. Their results also indicate that a failure of an individual supply line in the decentralized grid less likely implies an outage in the network as a whole, and that care must be taken when adding new links: paradoxically, additional links can reduce the transmission capacity of the network as a whole.

Synchronization, the coordinated dynamics of many units to the same timing is found throughout the natural world. Neurons in the brain often fire simultaneously, fireflies synchronize their blinking lights, and crickets chirp in shared rhythm. A similar form of harmony is also necessary in electricity networks, in that all generators and all machines that consume electricity must be tuned to the grid frequency of 50 Hertz. The generators of large power plants are regulated in such a way that they stay in rhythm with the power grid. The grid, in turn, imposes its frequency on the washing machines, vacuum cleaners and fridges at the other end of the line, so that all elements remain in synchrony, avoiding short circuits and emergency shutdowns.

In the course of the energy turnaround, however, the structure of the power grid will change. Today's large power plants that supply energy to the surrounding areas will be largely replaced by multiple photovoltaic panels on roofs, biogas systems on fields, and wind turbines on hills and offshore. Power lines will no longer form star-like networks and only transmit energy from large power plants to nearby consumers, but will look more like dense fishing nets linking many generators with the consumers. Experts believe it will be very difficult to bring this multiplicity of small generators into synchronous harmony. In effect, it would be like conducting a huge orchestra with thousands of musicians, instead of a chamber orchestra. However, as the Network Dynamics Group, headed by Marc Timme at the Max Planck Institute for Dynamics and Self-Organisation in Göttingen has now discovered, synchronization in a decentralized power grid may actually be easier than previously thought, as a grid with many generators finds its own shared rhythm of alternating current.

How robust is the power grid? Using the British grid as an example, the Göttingen-based scientists calculated what happens when individual lines are cut. If one of the blue lines is cut, an outage in the whole network is unlikely. In the case of the dark red lines, however, the likelihood of a total blackout rises to almost 50 per cent. © Dirk Witthaut and Marc Timme / MPI for Dynamics and Self-OrganisationHow robust is the power grid? Using the British grid as an example, the Göttingen-based scientists calculated what happens when individual lines are cut. If one of the blue lines is cut, an outage in the whole network is unlikely. In the case of the dark red lines, however, the likelihood of a total blackout rises to almost 50 per cent. © Dirk Witthaut and Marc Timme / MPI for Dynamics and Self-Organisation

In a decentralized grid, power plants and consumers synchronize themselves

The Göttingen-based scientists have simulated a dense network of small generators and consumers. Their computer model calculates the grid for an entire country (for practical reasons, they chose Great Britain) and takes into account the oscillations of all generators and electric motors that are connected to the grid. Combining this level of detail with this grid size is a new departure. Previously, the dynamics of the oscillating 50 Hertz AC current was basically only simulated for small networks. Simulations for larger grids did exist, but they were generally used only to make predictions regarding the static properties of the network, such as how much electricity would be transmitted from A to B. They completely ignored the oscillations of the generators and electric motors. "Our model is sufficiently complex and extensive to simulate collective effects in complex networks and, just as importantly, it is simple enough that we can understand these effects too", says Dirk Witthaut, project leader within the research group.

The scientists simulated a very large number of networks, each with a different structure. The networks consisted of different mixes of large and small generators with lines of varying capacities, a little like country lanes and motorways for electrical current. This enabled them to identify differences between centralized and decentralized power grids.

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Too bad we are running out of silver to make these solar panels.

Yet, we have an over abundance of both silver and gold. If we ever, "run out," we have all the gold and silver we could want in jewelry.

Refreshing to see the concept of local sloar and wind energy distribution being discussed. "Think Global, Act Local". I have long been an advocate of solar and wind power generation and it really frustrates me when I see the vast acreages of roof-tops (homes and commercial) being nothing but a barrier to the environment. A social (thinking) change is needed to bring into reality self-sufficiency in energy. My latest website http://www.solarandwindpowerreviews.com/ is a small contribution towards a changing way of thinking.