Analysis of smart meter data has shown that renewable energy fed into the main grid can destabilize the system and potentially cause power outages.
In the new study, mathematicians at the University of Nottingham used data from smart meters to track how the grid’s composition changes over time and found that resilience varies over the course of a day and a high uptake of solar panels can make the grid more prone to failures. Their findings have been published in scientific progress†
Just over a million small-scale residential photovoltaic (PV) systems have been installed in the UK. These small-scale, renewable generators are low-powered and intermittent, and are often distributed in large numbers and embedded in power grids.
Household generation is an important part of the integration of renewable energy sources and includes the ‘feed-in tariff’ that the producer pays for feeding its stored electricity back to the grid. This power supply is unpredictable with generators turning on and off intermittently and households taking on the role of consumer or producer as daily and seasonal use and meteorological conditions vary. According to the researchers, these fluctuations can put the network at risk of system failure.
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In a statement, study leader Oliver Smith said: “The increasing proliferation of small, intermittent renewables is causing rapid change in the structure and composition of the power grid. The effective structure of the grid can change over the course of a day as consumers and small-scale generators get online and offline.
“Using data from smart meters in UK households, we tracked how the grid composition varies over time. We then used a dynamic model to assess how these changes affect the resilience of electricity grids against catastrophic failures We found that resilience varies over the course of a day and that high solar uptake can make the grid more susceptible to failures.”
The first part of the research explored the theory of changing the proportion and size of generators by modeling a system with many small-scale generators. In all cases it turned out that the grid should be more robust than when using a single power source. When the real-world smart meter data was included, the researchers found that the reality for a network with many small-scale generators operating at different times means that the grid does not reach the optimum level to achieve this resilience, leaving it prone to failures. .
The researchers found that renewable energy stored in household batteries is only used to minimize household power costs and does little to minimize the risk of network outages. They recommend that the delivery of power from these batteries should be planned to also optimize for the resilience of the power grid.
“The biggest problem is the degree of fluctuation in the small-scale renewable energy supply,” Smith says. “A cost-effective way to overcome this would be to intelligently schedule the release of stored PV energy from household batteries at specific times. This would provide much more control and reduce the risk of system failure.”