This slide is an introductory part of the course Computer Application in Power system. it will describe the basic tasks of a computer and different computer application areas.

1. ASTU
SCHOOL OF ELECTRICAL ENGINEERING AND
COMPUTING
DEPT. OF POWER AND CONTROL ENGINEERING
COMPUTER APPLICATION IN POWER SYSTEM
(PCE5307)
CHAPTER ONE
INTRODUCTION
BY: MESFIN M.

2. OUTLINE
 Computers in Power System
Computer Tasks
AGC
SCADA
Generation Schedule
Network Analysis
Transmission System Development
Interactive Power System Analysis

3. COMPUTERS IN POWER SYSTEM
 The appearance of large digital computers in the 1960s
paved the way for unprecedented developments in power
system.
The emphasis in modern power systems has turned from
resource creation to resource management.
The two primary functions of an energy management
system are security and economy of operation

4. CONT.…
In the present state of the art the results derived by the
center computers are normally presented to the operator
who can then accept, modify or ignore the advice received.
However, in the longer term the operating commands
should be dispatched automatically without human
intervention

5. COMPUTERS TASKS
 The basic power system functions involve very many
computer studies requiring processing power capabilities in
millions of instructions per second (MIPS).
 The most demanding in this respect are the network
solutions, the specific task of electrical power system
analysis.

6. CONT.…
The main computer tasks involved in the management of
electrical energy systems are as follows.
AGC
SCADA
Generation Schedule
Network Analysis

7. AUTOMATIC GENERATION CONTROL (AGC)
As the system load changes continuously, the generation
is adjusted automatically to restore the frequency to the
nominal value. This scheme is called AGC.
During normal operation the following four tasks can be
identified with the purpose of AGC:

8. CONT.…
1. Matching of system generation and system load.
This task is met by governor speed control.
2. Reducing the system frequency deviations to zero.
3. Distributing the total system generation among the various control
areas to comply with the scheduled tie flows.
The 2nd & 3rd tasks are associated with the load-
frequency control

9. CONT.…
4. Distributing the individual area generation among its generating
sources so as to minimize operating costs.
This task is the economic dispatch function of AGC.

10. SCADA
 Stands for “Supervisory Control And Data Acquisition”
SCADA encompasses the collecting of the information, transferring
it back to the central site , carrying out any necessary analysis and
control and then displaying that information on a number of operator
screens or displays.
The modern utility control system relies heavily on the operator
control of remote plant.

11. CONT.…
In this task the operator relies on SCADA for the following
tasks:
Data acquisition
Information display
Supervisory control
Alarm processing
Information storage and reports
Sequence of events acquisition
Data calculations

12. GENERATION SCHEDULING
 The operation scheduling problem is to determine which generating
units should be committed and available for generation,
In general, utilities may have several sources of power such as
thermal plant (steam and gas), hydro and pumped storage plants,
dispersed generation (such as wind power or photovoltaic),
interconnections with other national or international companies, etc.
Also many utilities use load management control to influence the
loading factor, thus affecting the amount of generation required.

13. CONT.…
The economic effect of operations scheduling is very
important when fuel is a major component of the cost.
Large steam turbines take several hours to start up and
bring on-line; moreover they have costs associated with up-
and down-time constraints and start-ups.
Other factors to be considered are maintenance schedules,
nuclear refueling schedules and long-term fuel contracts.

14. NETWORK ANALYSIS
 This is by far the more demanding task, since it develops
basic information for all the others and needs to be
continuously updated.
The primary subject of power system analysis is the load-
flow or power-flow problem
It is also needed to determine the state of the network prior
to other basic studies like fault analysis and stability.

15. SECURITY ASSESSMENT
 The overall aim of the economy-security process is to operate
the system at lowest cost with a guarantee of continued
prespecified energy supply during emergency conditions.
An emergency situation results from the violation of the
operating limits and the most severe violations result from
contingencies.
A given operating state can be judged secure only with
reference to one or several contingency cases

16. OPTIMAL POWER FLOW
 The computational need becomes even more critical when it is
realized that contingency-constrained optimal power flow (OPF)
usually needs to iterate with contingency analysis.
The purpose of an on-line function is to schedule the power system
controls to achieve operation at a desired security level while
optimizing an objective function such as cost of operation.
The ultimate goal is to have the security-constrained scheduling
calculation initiated, completed and dispatched to the power system
entirely automatically without human intervention.

17. TRANSMISSION SYSTEM
DEVELOPMENT
 The basic algorithms developed by power system analysts are
built around conventional power transmission plant with linear
characteristics.
The advances made in power electronic control, the longer
transmission distances and the justification for more
interconnections (national and international) have resulted in
more sophisticated means of active and reactive power control
and the use of HVDC transmission.

18. CONT.….
 Although the number of HVDC schemes in existence is
still relatively low, most of the world’s large power systems
already have or plan to have such links.
considering the large power ratings of the HVDC schemes,
their presence influences considerably the behavior of the
interconnected systems and they must be properly
represented in power system analysis.

19. INTERACTIVE POWER SYSTEM
ANALYSIS
 Probably the main development of the decade in power system
analysis has been the change of emphasis from mainframe-based to
interactive analysis software.
Until IBM introduced the PC/AT in 1984 it was out of the question to
use a PC to perform power system analyses.
At the time of writing, the 32-bit architecture and speed of the Intel
8086 chip combined with the highly increased storage capability and
speed of hard disks has made it possible for power system analysts to
perform most of their studies on the PC.