The plant capacity factor is defined as the ratio of actual power generated to the maximum possible power that could have been generated. Just like load curve, the plant capacity factor is also specified for a given period of time.
If the time specified is represented as T, the above formula equates
If the time period is considered as 1 year, then the plant capacity factor will be annual
Plant capacity factor and reserve capacity
The plant capacity factor is an indicator of the reserve capacity of the power plant.
The primary concern of power plant engineering is to design the plant in a way that it has some reserve capacity for meeting future load demands. The installed capacity of the power plant is always kept somewhat greater than the maximum demand on the plant.
The mathematical formula for reserve capacity is:
Reserve capacity = Plant capacity – Maximum demand
The difference between the load factor and plant capacity factor is an indicator of reserve capacity.
If the maximum demand on a power plant is equal to the plant capacity, then the load factor and plant capacity factor will have the same value and in such a case, the plant will have no reserve capacity.