What does utility frequency mean?

As the name suggests, alternating current changes its polarity continuously. This is achieved by generating a voltage force between two oppositely charged poles. Charged particles are set in motion between the poles for current to flow. This is the electrical voltage; it is the basic requirement for electricity to flow at all. A higher difference between the charged poles results in higher electrical voltage, which is measured in volts (V). Higher voltage leads to a higher electrical output. The following formula applies:

P (electric power) = V (electric voltage) *A (electric current)

A closely interconnected grid operated by alternating voltage requires a steady frequency that is largely constant over time. The frequency denotes how often the polarity changes between two points.
 

The interconnected European grid now only experiences minor deviations from the nominal value of 50 Hertz. However, as recently as the 1980s in the former German Democratic Republic, it was by no means uncommon for the utility frequency to drop by one or two Hertz on days with lower electricity generation. Even today, small deviations in the utility frequency have very practical consequences: Utility frequency is used as a time signal for simple electronic devices such as clock radios. In the spring of 2018, a drop in the utility frequency throughout Europe led to many delays in schools and offices, as the low utility frequency caused clock radios to run slower and sound their alarms later.
However, according to a press release from the Association of Transmission System Operators ENTSOE-E, these utility frequency deviations were not caused by specific physical or technical issues in the electricity grid, but by a political dispute between Serbia and the Autonomous Republic of Kosovo. Currently, 113 GWh of unsupplied electricity remain uncompensated. According to the ENTSOE-E press release, a political compensation solution is still pending.