Terms & Definitions

Load profile Load profile chart- Load curve In electrical engineering, a load profile is a graph of the variation in the electrical load versus time. A load profile will vary according to customer type (typical examples include residential, commercial and industrial), temperature and holiday seasons.

Power generation In the electricity generation sector, a load curve is a chart showing the amount of electricity customers use over a period of time. Generation companies use this information to plan how much power they will need to generate at any given time.

Load curve Load in KW Time in Hrs ( clock Hrs)

Daily load curve 700 200 Load in KW 150 Time Hrs

Load curve Avarage Load Load in KW 24 00 18 08 Time Hrs Max demand, peak load Avarage Load Load in KW 24 00 18 08 Time Hrs

Load Factor The ratio of the average load supplied during a designated period to the peak load occurring in that period, in kilowatts. Simply, the load factor is the actual amount of kilowatt-hours delivered on a system in a designated period of time as opposed to the total possible kilowatt-hours that could be delivered on a system in a designated period of time. Utilities are generally interested in increasing load factors on their systems. A high load factor indicates high usage of the system’s equipment and is a measure of efficiency. High load factor customers are normally very desirable from a utility’s point of view. Using a year as the designated period, the load factor is calculated by dividing the kilowatt-hours delivered during the year by the peak load for the year times the total number or hours during the year.

LF some examples NTPC Simhadri Power eyes 92% plant load factorBS Reporter / Chennai/ Visakhapatnam May 14, 2008, 4:06 ISTNTPC Simhadri Super Thermal Power Project, which operates a 1,000Mw plant at Parawada, near Visakhapatnam, is targeting to achieve 92 per cent plant load factor (PLF) during the current fiscal. Last year, the PLF of the unit was only 88.5 per cent as against 92 per cent in 2006-07, owing to turbines overhaul works, R Venkateswaran, general manager, Simhadri Power Plant, said. Due to drop in PLF, power production reduced to 7,779.66 million units in 2007-08 from 8,026 million units in the preceding year, he told the media. NTPC is adding another 1,000 Mw at the Simhadri plant and the stage-II units will start production from 2011-12. Power purchase agreements for the Simhadri stage-II have been signed with discoms of Andhra Pradesh, escoms of Karnataka and Tamil Nadu, Kerala and Puducherry electricity boards. Over 30 per cent of the Stage-II production would be dedicated to Andhra Pradesh, he stated. The Simhadri power station utilised 70.54 per cent of ash produced during the year 2007-08. The plant has been generation about 2 million tonnes of ash annually, he added.

Load factor Load factor (electrical) is the average power divided by the peak power over a period of time. in the electricity industry, load factor is a measure of the output of a power plant. The two commonest definitions are: 1. the ratio of average load to peak load in a period. 2.the ratio of actual energy produced to The maximum energy that could have been produced if the maximum demand stays on for all the time. A higher load factor is better: * A power plant may be less efficient at low load factors. * A high load factor means fixed costs are spread over more kWh of output. * A high load factor means greater total output.

Load Factor Daily LF

Load Factors Based on the period considered (Day,Week, Month,or year) Daily LF Weekly LF Monthly LF Yearly LF

Diversity factor Diversity factor: The ratio of sum of the individual non-coincident maximum demands of various subdivisions of the system to the maximum demand of the complete system. The diversity factor is always more than or equal to 1. Diversity Factor = --------------------------------- Sum of Individual max demand Max demand on Power station

Load duration curve Time 00 to 08 08 To 18 18 to 24 Load in kW 200 700 150

Load duration curve A load duration curve is similar to a load curve. The information is the same but is presented in a different form. These curves are useful in the selection of generator units for supplying electricity.

A load duration curve (LDC) is used in electric power generation to illustrate the relationship between generating capacity requirements and capacity utilization.

A LDC is similar to a load curve but the demand data is ordered in descending order of magnitude, rather than chronologically.

The LDC curve shows the capacity utilization requirements for each increment of load. The height of each slice is a measure of capacity, and the width of each slice is a measure of the utilization rate or capacity factor. The product of the two is a measure of electrical energy (e.g. kilowatthours).

A load duration curve