8 Artifi cial Intelligence in Power System Optimization
operating zones and multiple fuels are introduced. Other economic dispatch
problems of multi-objective, combined heat and power and hydrothermal systems
are also presented. An optimal dispatch solution for a competitive electricity
market is also covered. Complementary, in this chapter, solution methods based
on artifi cial intelligence including particle swarm optimization and augmented
Hopfi eld Lagrange network are described. The particle swarm optimization method
developed through simulation of simplifi ed social models is one of the most modern
heuristic algorithms. It can deal with non-convex optimization problems similar
to other evolutionary algorithms. The Augmented Lagrange Hopfi eld network
is a continuous Hopfi eld neural network having its energy function based on an
augmented Lagrange function. This network is simpler than a Hopfi eld network
and more effi cient in fi nding the optimal solution within a shorter computational
time. In addition, fuzzy linear programming, a method based on the vagueness in
linguistics, is also used for solving economic dispatch problems in traditional and
competitive markets. The mathematical models and explanations for these methods
are also provided so that the reader can easily understand them.
In Chapter 3, unit commitment is used as the criteria for operation planning
for one day up to one week ahead based on load forecast considering generating
unit statuses as discrete variables and time dependent constraints. The solution
methods have to handle both continuous and discrete variables. In this problem,
many constraints are considered such as ramp rate, transmission line, environmental
emissions, fuel limitations etc. Additionally, the unit commitment approach in
competitive markets based on the maximization of total revenue is also considered.
The methods suggested in this chapter are a new adaptive Lagrangian relaxation
and hybrid systems based on generating a unit merit order, Hopfi eld network
and Lagrangian relaxation. In the adaptive Lagrangian relaxation method, the
Lagrangian multipliers are adaptively adjusted to enhance the convergence rate.
Moreover, introducing a new on/off criterion also improves the convergence in this
method. The augmented Lagrange-augmented Hopfi eld network is also an effi cient
method to solve the unit commitment problem. This method is a combination of
both continuous and discrete Hopfi eld networks with its energy function based
on the augmented Lagrange function. Another method based on a merit order of
generating units is also effi cient in resolving unit commitment issues. The merit
order of generating units based on their average production cost is effective in
determining the thermal unit scheduling. In the methods based on this, heuristic
search is needed to enhance the results or repair constraint violations. Besides this,
the sub-procedures of these methods for certain tasks are illustrated.
One of the most complex problems in generation scheduling optimization,
hydrothermal scheduling, is presented in chapter 4. The role of hydro power
plants has become more important in power systems due to their comparably low
environmental impact and—over lifetime—marginal cost. However, the capacity
of hydro power plants depends on reservoir capacity and weather. Therefore, the
optimal scheduling of hydro-thermal systems is of utmost importance, especially