Power-Grid Load Balancing by Using Smart Home Appliances

Climate change is one of the greatest environmental, social and economic threats facing the planet, and can be mitigated by increasing the efficiency of the electric power generation and distribution system. Dynamic demand control is a low-cost technology that fosters better load balancing of the electricity grid, and thus enable savings on CO2 emissions at power plants. This paper discusses a practical and inexpensive solution for the implementation of dynamic demand control, based on a dedicated peripheral for a general-purpose microcontroller. Pre-production test of the peripheral has been carried out by emulating the actual microprocessor. Simulations have been carried out, to investigate actual efficacy of the

proposed approach.

Global warming is a major concern nowadays, mostly due to the increase on greenhouse gases concentration in the atmosphere. Power plants burning fossil fuel are responsible for a significant fraction of greenhouse pollutants emission. Among many issues, the global efficiency of power grid is limited by the need of providing a sufficient amount of spare power to face unpredictable demand peaks. Renewable energy sources (wind, solar plants) cause much lower pollution, but provide an inherently intermittent supply, thus again resulting

in grid balancing issues. Erratic load imbalances are compensated, at the supply-side, by a service called

“response”, which involves the use of spare generators. Such generators usually operate at low-output regimes to provideback-up capacity, and their efficiency is lower than at fullpower regimes. This relatively increases the greenhouse gas emissions. Consequently, there is a growing interest for demand-side techniques which, by adapting the user’s load to the grid actual availability, would help in smoothing out fluctuations in the power requirement.

Dynamic Demand Control (DDC) technology has been proposed in late ’70s as a solution directed to reduce

costs of electric power. It aims at a better matching between power supply and demand by exploiting self-balancing capability on the load’s end, rather than relying on statistical prediction on the power-grid end. Recently, the DDC approach has been retrieved: energy authorities are interested in incentivating DDC technology and UK Government has recently supported a large-scale field-trial. Nevertheless, cheap devices are needed to support massive deployments: in this abstract, a device conceived for low-cost DDC implementation in home digital appliances is presented.

II. DYNAMIC DEMAND CONTROL

DDC is sensitive to the mains frequency. Power grid operators have to keep the frequency within strict limits (e.g. fmains = 50 ± 0.5 Hz in several European countries). In practice, the frequency normally remains within even stricter bounds (± 0.2 Hz) but changes on a short time basis (minutes or even seconds). A frequency decrease can be correlated to an increase of the grid load , so that a frequency monitor could be exploited to evaluate the stress status of the grid. At the user’s side, such an information can be used to decide whether inserting a load or waiting for an healthier grid status: a wide variety of home appliances may indeed tolerate

moderate time shifts in their operating cycle without compromising their function (e.g., heaters, air conditioners, fridges, freezers, etc.). DDC allows the load to re-schedule its power request, according to the actual power-grid availability. If a large number of DDC-enabled device were connected, this would result in a self-balancing capability of the global network, ensuring a more stable cumulative load and thus reducing the need for spinning reserves.