By: Phil Kemble

Phil Kemble
Thu, 26 Jun 2025 12:11:46 +0000

The grid is balanced to 50Hz (50 cycles per second). This includes the generator in the power station which turns at 3,000 RPM (equates to 50 revolutions per second). If there is a fault somewhere in the grid, it can cause the frequency to change. A change in frequency alters the impedance that the line sees which in turn alters the voltage. A small change in frequency can cause the voltage to change dramatically leading to the system closing down. This is what happened in Spain. The sheer weight of the rotor turning in the generator in the power station produces inertia power. This inertia power fights against any frequency change thereby rebalancing the grid preventing any voltage change and the grid closing down. The more conventional power stations on the grid, the greater the inertia power.

There is no inertia power in renewables, so the more renewables replace conventional power stations the less inertia power in the grid and the more susceptible the grid is to collapse as happened in Spain. Inertia flywheels in renewable systems may overcome this problem. Not sure how advanced they are currently in practically working which is concerning considering the mad rush to net zero. Another problem with renewables is that they produce DC which cannot be used by the grid. Inverters are needed to convert the DC to 50Hz AC. I’m a retired electronics engineer but I also qualified in electrical engineering.