CHAPTER hence at the same time it

CHAPTER 1

INTRODUCTION

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1.1 
General

Electricity
expanded rapidly throughout the world after invention. Electrical power systems
in the world have grown larger and more geographically expansive with many
interconnections between neighboring systems. India has also grown in
production of electricity. India has recorded impressive rates of economic
growth in recent years.

 

Electrical power
sectors play an
important role in national economy. Growth in
production of electricity has led to its extensive use in all the sectors of
economy. The growth in all sectors increases very rapidly and hence the demand
of electricity increases in the same ratio. The demand rate of electrical power
is very large as compared to generation of power.

 

Since electrical power
system has limited power generation and hence at the same time it is very
difficult task to satisfy the demand of all electrical consumers. It is also
very difficult task to provide electric power at a reasonable rate of price. So
that it is required to reduce the total generation cost of the electrical power
plants and fulfill the load demand.

 

Power system has
several generating power plants. Each generating power plant have several
generating units.  The total demand of the
system is supplied by different generating power plant at any particular time.
Economic load dispatch problem identify the generated output power of each generating
power plant and output power of each generating unit within a power plant in
such a way to minimize the overall generation cost in order to provide the
system load demand and not violate the constraints limits.

 

In the economic
load dispatch the generations are not fixed but they are allowed to take values
within certain limits so as to meet a particular load demand with minimum fuel
cost. Economic load dispatch problem is really the solution of a large number
of load flow problems and choosing the one which is optimal in the sense that
it needs minimum cost of generation. Since total cost of generation is a
function of the individual generation of the sources which can take values
within different constraints, the cost of power generation depends on the operating
constrains of the sources.

 

By proper planning
and design of power plant can be operate economically and efficiently.  Economic load dispatch used for analysis,
planning and design of the power system which operate economically and
efficiently. Economic load dispatch also used for the study of transient stability
and contingency studies of the power plant.

 

Power system fuel
cost problem numerically can be analyzed by the use of economic load dispatch. The
most important objective of the economic dispatch problem is to minimize the
total generation cost while satisfying the operational constraints.

 

Conventional economic
load dispatch would be considered as linear model and many algorithms were
proposed by researchers for the solution of such linear model, such as lambda-iteration
method, the base point, linear method, non-linear method, gradient method and
interior point method etc. But unfortunately, the input-output characteristics
of modern units are inherently highly non-linear because of valve point
loadings, prohibited operating zones and ramp rate limits etc., resulting in
multiple local minimum points in the cost function.

 

The characteristics
of economic load dispatch problem have to be approximated to meet the
requirements of the classical dispatch algorithms, however, such approximations
may lead to huge loss of revenue and time. The classical gradient-based
techniques failed in solving these types of problems.

 

Most recent trends
for research, therefore, have been directed towards application of evolutionary
algorithms i.e. GA, ES and EP. These evolutionary algorithms are search
algorithms based on the simulated evolutionary process of natural selection and
genetics. Evolutionary algorithms are more flexible and robust than
conventional calculus based methods.

In this work we have considered the test data of Satpura Thermal
Power Plant, solved by Ant colony optimization and its results are compared by
PSO.

 

1.2 Generation of Electricity by Various
Sources

Figure
1.1 shows that all India gross electricity generation through generating plants
was 13,654 Mega Watt (MW) during 1970-71. It rose to 27,680 MW during 1980-81,
to 63,636 MW during 1990-91 and to 1,05,046 MW during 2001-02.

 

 

Figure 1.1: Electrical
power generation by different sources

 

The production of
electricity was 1,32,329 MW during 2007-08, it rose to 1,99,877 MW during
2011-12, registering an annual growth rate of about 9.00%. Total Electricity
generation in the country from utilities and non-utilities taken together till
30 november 2017 was 3,26,841 MW. Out of this 1,92,971.5 MW was generated from
thermal and 49,352.97 MW was from hydro and 6,780 MW was generated from nuclear
sources.

 

1.3 Role of Economic Load
Dispatch and its importance in power system

As
discussed about the scenario of energy in India, it is seen that the demand of
electrical energy is much more than the production rate of the electrical
power. Also it is seen that the maximum power is generated by thermal power
plant and hence the load demand much depends on the thermal power plant. In
this situation the rate of per unit power generation increase very rapidly
because the rate of fuel cost increase worldwide. So if we have some way to
fulfill the load demand and at same time reduce the total generation cost of
the thermal power plant and hence the rate of per unit energy charges get
reduce, it will economical for consumers as well as producers. In this contest
we have to need some tool used to calculate fuel cost of the thermal power plants. 

 

Economic load
dispatch is an important optimization task in power system operation for
allocating generation among the committed units such that the constraints
imposed are satisfied and the energy requirements in terms of British thermal
units per hour (Btu/h) or dollar per hour ($/h) or rupees per hour (Rs/h) are
minimized. Improvements in scheduling the unit outputs can lead to significant
cost savings.

 

The efficient and
optimum economic operation of electric power systems has always occupied an important
position in electric power industry. In recent decades, it is becoming very
important for utilities to run their power systems with minimum cost while
satisfying their customer’s demand all the time and trying to make profit.
Since the demand is very large and the power generation is limited so it is
required to fulfill the load demand using committed generating units in minimum
fuel cost.