Lesson Introduction Review: Lesson 6 The previous Lesson was about Gas turbine Power station. The student/User is expected to remember the following from the lesson 6. Basics: Arrangements: Advantages & Disadvantages: Definition components that make up a gas turbine power station. How this station measures up Preview: Lesson 6 This Lesson is about Variable loads on Power stations. The student/User is expected to understand the following at the end of the lesson. Definitions Load Curves Types of loads on a power station Selecting generation units for a power station Base & Peak loads Methods of meeting load To begin this lesson we look at definitions that will be used. learn these well.
Lessons in ELECTRICAL POWER GENERATION
Lesson #1:
Lesson #2:
Lesson #3:
Lesson #4:
Lesson #5:
Lesson #6:
Lesson #7:
 Power Generation: Variable load← You are here
Lesson #8:
Quiz Test:
Course Formula Sheet:

Part 1: Definitions
 Maximum demand ( MD ): The greatest demand of load on the power station during a given period. The highest peak on the power station load curve. Demand Factor ( Dem.F ): Ratio of maximum demand to connected load. this is usually less than 1. $Dem.F = \frac{MD}{Con_.Load}$ Average load ( MD ): This is the average of loads occuring on the power station in a given period. Daily average load: Average of loads occuring on a power station in 1 day (24Hrs). $= \frac{Total_.of_.units(in_.kWh)}{24Hrs}$ Monthly average load: Average of loads occuring on a power station in 1 month (24Hrs x No. of days). $= \frac{Total_.of_.units(in_.kWh)}{24Hrs \times days}$ Yearly average load: Average of loads occuring on a power station in 1 year (8760Hrs). $= \frac{\sum Total_.of_.units(in_.kWh)}{8760Hrs}$ Load factor ( LF ): The ratio of average load to maximum demand. typical ≈ less than 1. This is the measure of the effective use of the power station. $LF = \frac{Load_{ave}}{MD} = \frac{Output_{Annual}(in_.kWh)}{(Capacity_{Installed} \times 8760Hrs)}$ High LF = Low MD = Low plant capacity = Low cost per unit generated. Diversity factor ( DF ): The ratio of the sum of all individual maximum demands on the power station to the Maximum demand on the station. Consumer maximum demands donot occur at the same time thus maximum demand on power station will always be less than the sum of individual demands. $DF = \frac{MD_{individual}}{MD_{On_.station}}$ High DF = Low MD = Low plant capacity = Low investment capital required. Plant capacity factor ( PCF ): The ratio of actual energy produced to the maximum possible energy that could have been produced on a given period. $PCF = \frac{kWh_{per annum}}{Plant_.Capacity \times 8760Hrs}$ This indicates the reserve capacity of a plant. From these we can see that: $Units_.generated = MD \times LF \times 8760Hrs$

 Part 2: Introduction Objectives of a Power station: The power station is constructed, comissioned and operated to supply required power to consumers with generators running at rated capacity for maximum efficiency. we saw in lesson one that the fundamental problem in generation, transmission and distribution of electrical energy is the fact that electrical energy can not be stored. It must be generated, transmitted and distributed as and when needed. This lesson looks at problems associated with variable loads on power stations, and discusses the complexities met in deciding the make, size and capacity of Generators (Generating units) that must be installed in a power plant to successfully meet these varying energy demands on a day to day basis. Variable load: The load on a power station varies from time to time due to uncertain demands of consumers. Energy demand of one consumer at any given time is distinct/differs from the energy demand of another consumer. This results in the total demand on the power station to vary over a given period of time and may necesitate the following: Additional equipment/Generating units to meet demand Increase in production cost to recuperate use of more material/equipment In order to study the pattern and effect of the varying load, station engineers use load curves.