  The electrical generation and transmission infrastructures of many countries
are under increased pressure. This partially reflects the move towards low
carbon economies and the increased reliance on renewable power generation
systems. There has been a reduction in the use of traditional fossil fuel
generation systems, which provide a stable base load, and this has been
replaced with more unpredictable renewable generation. As a consequence, the
available load on the grid is becoming more unstable. To cope with this
variability, the UK National Grid has placed emphasis on the investigation of
various technical mechanisms (e.g. implementation of smart grids, energy
storage technologies, auxiliary power sources), which may be able to prevent
critical situations, when the grid may become sometimes unstable. The
successful implementation of these mechanisms may require large numbers of
electrical consumers (e.g. HVAC systems, food refrigeration systems) for
example to make additional investments in energy storage technologies (food
refrigeration systems) or to integrate their electrical demand from industrial
processes into the National Grid (HVAC systems). However, in the situation of
food refrigeration systems, during these critical situations, even if the
thermal inertia within refrigeration systems may maintain effective performance
of the device for a short period of time (e.g. under 1 minute) when the
electrical input load into the system is reduced, this still carries the
paramount risk of food safety even for very short periods of time (e.g. under 1
minute). Therefore before considering any future actions (e.g. investing in
energy storage technologies) to prevent the critical situations when grid
becomes unstable, it is also needed to understand during the normal use how the
temperature profiles evolve along the time inside these massive networks of
food refrigeration systems.
