Powerplant

Variable Load Problems

A variable load in a power plant is the changing demand for power from consumers, which can result in a power station's load varying over time.

Additional equipment

Power plants need extra equipment to adjust the supply of raw materials to meet the changing demand for power. For example, a steam power plant needs to increase the flow of air, coal, and water to the boiler when demand increases.

Increased production costs

  Variable loads increase the cost of producing electricity. Alternators are most efficient when operating near their rated capacity, so a single alternator will be inefficient during periods of low demand.

Load duration curve

When the load elements of a load curve are arranged in descending order, the resulting curve is called a load duration curve. 

Load Curve

refers to the graph used to represent the relationship between the demanded load and time sequence.

Monthly Load Curve

is the average of the daily load curves over a one-month period that is used in establishing the rates

•Annual Load Curve

is the average of the daily load curves over a period of one year that is used in determining the annual load factor.

Load Duration Curve

is obtained from the same data as the daily load curves for one year or a period of 8,760 hours.

Base Load Power Plant

include steam, hydro-electric and geothermal power plants.

•Peak Load Power Plant

include diesel – electric and gas turbine power plants.

1.Reserve Over Peak

also known as “reserve margin”, is a measure of the extra supply of electricity available in a given region compared to the expected peak demand

 Average Load

also known as “average demand”, is the average of loads on a power station over a given period of time, such as a day, month, or year.

Load Factor

is the ratio of the average load over a designated period of time to the peak load occurring in that period.

 Capacity Factor

is the ratio of the average load on a machine or equipment, for the period of time considered, to the rating of the machine or equipment.

Annual Capacity Factor

is a measure of how often a power plant runs at its maximum capacity, and how much electricity it generates relative to its theoretical maximum over a year.

. Use Factor

is the ratio of kWh generated to the product of plant capacity and the number of hours for which the plant was in operation.

Demand Factor

is the ratio of the maximum demand of a system, or part of a system, to the total connected load of the system, or part of a system under consideration.

Diversity Factor

is the ratio of the sum of the individual maximum demands of the various subdivisions of a system, or part of a system, to the maximum demand of the whole system, or part under consideration.

Utilization Factor

is the ratio of the maximum demand of a system, or part of a system, to the rated capacity of a system, or part of a system under consideration.

Operation Factor

is the ratio of the duration of the actual service of a machine or equipment to the total duration of the period of time considered.

Plant Factor

the ratio of a plant's average power load to its rated capacity. It's calculated by dividing the average demand by the plant capacity. Plant factor indicates a plant's reserve capacity, or how much extra capacity it has.

Regenerative cycle

The process of utilizing bled steam for reheating feedwater.

Reheat Regenerative Cycle

Reheat ang regenerative cycle combined

Reheat regenerative cycle

Improvement in overall thermal efficiency.

Reheat regenerative cycle.

Reduction in moisture content of steam