The document discusses key terms related to electric power generation systems and operations. It defines reserve capacity, operating reserve, average demand, maximum demand, base load and peak load. It also discusses load curves, load duration curves, mass curves, demand factor, load factor, diversity factor, capacity factor, use factor and different tariff structures. Factors that help determine the optimal size and number of generating units are also covered. The roles and challenges of electrical grids are outlined. Brownouts and blackouts are defined and distinguished.

1. Introduction to Electric
Generation Systems
Unit: 5

2. Economics of Power Generation and
Interconnected Power Station

3. Terms Commonly Used in System Operation
• connected load
• Firm power: Reserve Capacity of plant used for meeting emergency condition.
• Cold reserve: Reserve Capacity of plant in service but not in operation.
[200MW]
• Spinning reserve: Reserve Capacity of plant connected to the grid ready to
take load. [150MW]
• Hot reserve: Reserve Capacity of plant in operation but not in service. [50MW]
• Operating Reserve: In electricity networks, the operating reserve is the
generating capacity available to the system operator within a short interval of
time to meet demand in case a generator goes down or there is another
disruption to the supply.

4. Average Demand
• The average of loads occurring on the power station in a given
period (day or month or year) is known as average load or average
demand. The station capacity is so selected that it must meet the
maximum demand.

5. Maximum demand
• The maximum demand in kVA is nothing but a peak operating load
(maximum load) in kW of the consumer for the specific interval
divided by the operating power factor. The interval will be defined by
your electricity provider. Hence, the maximum demand formula can
be written as,
Maximum demand in kVA = Peak Load in kW / Power factor

6. Base Load and Peak Load defined
• Base load is the minimum level of
electricity demand required over a
period of 24 hours. It is needed to
provide power to components that
keep running at all times (also
referred as continuous load). Peak
load is the time of high demand.
These peaking demands are often
for only shorter durations.

7. Load Curve
• Load curve is the variation of load
with time on a Power Station. As
the load on a Power Station never
remain constant rather it varies
time to time, these variations in
load is plotted on half hourly or
hourly basis for the whole day. The
curve thus obtained is known as
Daily Load Curve.

8. Load Duration Curve
• Definition: The load duration curve is
defined as the curve between the
load and time in which the ordinates
representing the load, plotted in the
order of decreasing magnitude, i.e.,
with the greatest load at the left,
lesser loads towards the rights and
the lowest loads at the time extreme
right. The load duration curve is
shown in the figure below.

9. Integrated Duration Curve
• Integrated Load Duration Curve:
A plot of number of units
generated (kWh) for a given
demand (kW) is called
integration load duration curve
on Y-axis, load demand in kW or
MW is plotted while on X-axis
corresponding number of units
generated are obtained. Such a
curve corresponding to load
duration curve shown in Fig.

10. Determine the Average Load From the Load Curve
From load curve load distribution are
(0-6)hours -40MW for 6 hours
(6-10)hours -50MW for 4 hours
(10-12)hours -60MW for 2 hours
(12-16)hours -50MW for 4 hours
(16-20)hours -70MW for 4 hours
(20-24)hours -40MW for 4 hours
Total Load
=(40×6)+(50×4)+(60×2)+(50×4)+(70×4)+(40×4)
=1200MW
Total no of hours =24
Average Load =1200/24=50MW

11. Mass Curve
• A mass curve gives the total energy consumed by the load up to a
particular time in a day. This curve can be easily plotted from the
chronological load curve by summing up the energy consumed up to
different times starting at the zero time.

13. Demand factor
It is the ratio of maximum demand on the power station to its
connected load. The value of the demand factor is usually less than 1.
It is because maximum demand is always less than the connected load.
The knowledge of the demand factor is vital in determining the
capacity of the plant equipment.

14. Load Factor
• Load factor is defined as the ratio of the average load over a given
period to the maximum demand (peak load) occurring in that period.

15. Diversity Factor
• Diversity factor is defined as the ratio of the sum of the maximum
demands of the various part of a system to the coincident maximum
demand of the whole system.

16. Plant Capacity Factor
• The capacity factor is defined as the ratio of the total actual energy
produced or supply over a definite period, to the energy that would
have been produced if the plant (generating unit) had operated
continuously at the maximum rating.

17. Plant Use Factor
• It is defined as the ratio of energy produced in a given time to the
maximum possible energy that could have been produced during the
actual number of hours the plant was in operation.

18. Tariff
(i) Flat Rate Tariff:
This types of tariff differs from the former one in the sense that the different types of
consumers are charged at different rates i.e. the flat rate for light and fan loads is slightly
higher than that for power load. The rate for each category of consumers is arrived at by
taking into account its load factor and diversity factor.
(ii) Block Rate Tariff:
A block rate tariff, sometimes listed on energy bills as peak, demand or single rate, is a type
of tariff which charges customers a different price depending on how much electricity or
gas they have used.
(iii) Two Part Tariff:
The total energy charge to be made to the consumer is split into two components namely
fixed charge and running charge. This type of tariff is expressed as
Y = Rs a kW + b kWh
Where Rs a is the charge per kw of maximum demand assessed and Rs b is the charge per
kwh of energy consumed. This tariff is mostly applicable to medium industrial consumers.
18

19. Tariff
(iv)Three Part Tariff:
In this tariff total energy charge is split into three elements namely
fixed charge, semi-fixed charge and variable charge. Such a tariff is
expressed as
y = Rs a + bkW + c kWh.
Where a is a constant charge, b is unit charge in Rs per kw of maximum
demand in kw during billing period (in some case it is also charged in
Rs per kVA instead of Rs per kw) and c is the unit charge for energy in
Rs per kwh of energy consumed. This type of tariff is usually applicable
to bulk supplies.

20. Advantages of Interconnection
(I) EXCHANGE OF PEAK LOADS
(ii) USE OF OLDER PLANT
(iii) ENSURES ECONOMICAL OPERATION
(iv) INCREASES DIVERSITY FACTOR
(v) REDUCES PLANT RESERVE CAPACITY
(vi) INCREASES RELIABILITY OF SUPPLY

21. Load Flow Analysis

22. Load Flow Analysis

23. How do you choose a size and number of generating units?
• Important Points in the Selection of Units
1. The number and sizes of the units should be so selected that they
approximately fit the annual load curve of the station.
2. The units should be preferably of different capacities to meet the
load requirements.

24. How load curves help in the selection of size and
number of generating units?
The area under the daily load curve divided by the total number of hours
gives the average load on the station in the day. The ratio of the area under
the load curve to the total area of the rectangle in which it is contained
gives the load factor. The load curve helps in selecting the size and
number of generating

25. Electrical Grid
• Electrical grid or power grid is defined as the network which
interconnects the generation, transmission and distribution unit.
• Regional Grid – The Regional grid is formed by interconnecting the
different transmission system of a particular area through the
transmission line.
• National Grid – It is formed by interconnecting the different regional
grid.

26. What are the impact of grid failure?
• Blackout - Cascading failures - Control infrastructures of smart grids
affected
• Delay, blockage or corruption
• Downed wires - Economic and social disruptions
• Line faults

27. What causes grid failure?
However, the three most common causes are natural causes, human
error, and overload. Basically, any interruption between power
generation and the supply of electricity to homes can cause a power
outage. It can stem from inclement weather conditions, human error,
equipment failure, and even animal interference.

28. What is a grid fault?
• The grid is faulty when the peaks of voltage and frequency are
severe and exceeds the maximum margins mentioned in the
standards.

29. 7 Major challenges of a power grid and their solutions
1. Growing amount of renewable energy sources. ...
2. Electricity transmission losses. ...
3. Frequent power outages. ...
4. Electro mobility. ...
5. Grid modernization. ...
6. Threat of cyber attacks. ...
7. Threat of terrorist attacks.

30. What is Brownout?
A brownout is a temporary, partial abrupt drop in voltage level followed by a
quick recovery. It’s the opposite of a power surge in which case some electrical
motors do not work and room lights are dimmer than normal. This indicates
that the demand for power was momentarily greater than the supply, resulting
in reduced voltage, or a condition what is called a brownout. It is caused by
high electricity demand that is close to or above the production capacity of a
power grid system. Simply put, a brownout, sometimes called a sag if it lasts
for less than a second, refers to partial electrical supply failures of the energy
grid system which in turn affects some areas while others remain unaffected.
During a brownout, lights will flicker or become dimmer and unprotected
systems will often turn themselves off or restart. It is a strategy used by the
power grid utilities to prevent the system from a blackout condition.

31. What is Blackout?
As compared to a brownout, a blackout is a total disruption of electrical services
in an area for a longer period of time. A blackout, also called a power failure or
power cut, is a total crash of the power grid as a result of severe weather
conditions or equipment failure at power plants. It is a large-scale service
disruption which can last from hours to days and days to weeks in case of a
serious emergency or a natural disaster like storm, earthquake, flood, cyclone,
and so on. Blackouts usually happen due to an imbalance between power
generation and power consumption meaning more electricity is consumed than
power companies can supply. When the demand is higher than the supply,
power utilities cut back on the power they release in order to prevent a blackout
from happening, which allow them to save power for the times when it is
needed the most. They do that in two ways – a pre-planned brownout and a
rolling blackout.