Definition
Load following is the practice of increasing and decreasing generation over a period of many minutes to hours to track the diurnal pattern of demand and slower swings in net load, such as the gradual ramp of wind or solar output. It bridges the gap between slow, scheduled dispatch and fast, second-to-second regulation, keeping supply matched to the predictable daily shape of consumption.
Where load following sits
Power system balancing operates on several timescales. Frequency regulation handles the fastest, sub-minute fluctuations. Load following handles slower, more predictable changes over minutes and hours — for example, the morning demand ramp or the evening peak. A load-following resource typically transfers net energy (positive or negative) over an hour, but is expected to net out over a day. This makes it distinct from reserves held purely for contingencies.
Resources that follow load
Flexible generators — gas plants, hydro, and some thermal units — have traditionally provided load following by ramping output up and down. Responsive demand can contribute as well: a controllable load that raises consumption when demand is low and reduces it as demand climbs effectively follows load from the consumption side. As variable renewables grow, the need for flexible following capacity increases, since net load becomes harder to predict.
Load following is one of the balancing functions categorized among ancillary services, and demand-side participation links it to demand response.
In Simple Terms
Load following is the practice of increasing and decreasing generation over a period of many minutes to hours to track the diurnal pattern of demand…