From The Telegraph, May 16:
Green grids need the resilience of synchronous turbines
The Danish government plans to evaluate the prospect of beginning a nuclear power programme, this week lifting a ban imposed 40 years ago. Unlike its neighbours in Sweden and Germany, Denmark has never had a civil nuclear power programme. It has only ever had three small research reactors, the last of which closed in 2001.
Most of the renewed interest in nuclear seen around the world stems from the expected growth in electricity demand from AI data centres, but Denmark is different. The Danes are concerned about possible blackouts similar to the one that struck Iberia recently. Like Spain and Portugal, Denmark is heavily dependent on weather-based renewable energy which is not very compatible with the way power grids operate.
Conventional generators produce alternating current, creating a stable output of current and voltage that alternates at a frequency which is directly – synchronously – linked with the rotating turbines which drive the generators in gas, coal, nuclear or hydropower plants. All of these turbines rotate at a speed of 3000 revolutions per minute, so producing electricity with current and voltage that varies in a sine wave shape with a frequency of 50 cycles per second (ie 50 Hz)....***....Electrical equipment is highly sensitive to this frequency and can break if it deviates too much from 50 Hz. For this reason, power stations, substations, switching equipment and other devices in the grid have fail-safes which will cause them to trip out should frequency fall outside acceptable bounds.This frequency property is also connected to the balance between supply and demand: if there is more generation than consumption, frequency increases and the turbines speed up, and if there is more demand than generation, the opposite happens.
Fortunately, conventional generators are large heavy lumps of metal whose speed of rotation is hard to change. They oppose changes to their speed of rotation, providing resistance to changes in grid frequency, a property known as “inertia”.
However, wind and solar do not produce synchronous alternating current. Although wind turbines rotate, they do not do so at a constant speed, and solar has no moving parts at all. They produce direct current which is converted to alternating current using electronic devices known as inverters. Wind and solar also have no inertia....
....MUCH MORE
