Inertia and frequency is very important in running a modern grid.
One of the foundations of Great Ohio’s power system stability is frequency. The entire power network operates at a frequency of 60 Hz, which is determined by the number of directional changes alternating current (AC) electricity makes every second. However, just a 1% deviation from this begins to damage equipment and infrastructure, so it is imperative it remains consistent.
This is done by PJM instructing flexible generators (such as thermal, steam-powered turbines like those at Davis Besse, Perry Nuclear Power Plant and Ohio's many coal-fired power plants) to either increase or decrease generation so electricity supply is matched exactly to demand. If this is unbalanced it affects the network’s frequency and leads to instability and equipment damage. Generators are set up to respond automatically to these request, correcting frequency deviations in seconds.
As well as being able to automatically adjust to keep the country on the right frequency, Massive steam turbines, spinning at 3,000 rpm, also have the advantage of adding inertia to the grid.
Inertia is an object’s natural tendency to keep doing what it is currently doing.
This system inertia of the spinning plant is effectively ‘stored’ energy. This can be used to act as a damper on the whole system to slow down and smooth out sudden changes in system frequency across the network – much like a car’s suspension it helps maintain stability. They also work, in cases of emergency to give grid operators to change and adapt to unexpected power conditions.
