Short Course on

Energy Management System Essentials

Mohamed A El-Sharkawi, Mark J. Damborg

Department of Electrical Engineering

University of Washington

Seattle, WA 98195

Course Description

This course deals with the fundamentals of the control center tools and functions of energy management systems (EMS). A primary objective of the EMS is to maintain grid reliability to ensure customers’ demands are continually met around the clock.  The course begins with a brief history of the evolution of EMS functions and a summary of the main functions and tools available to the operators to maintain power system reliability under a wide variety of system operating conditions.  The tools available to the operators to steer the system back to the normal state should unfavorable events occur are emphasized. After establishing an appreciation for the control center’s role, each “mode” of power system operation is examined in detail. During any operating mode, the operator’s focus on specific objectives based on the data gathered from the system and by using specific tools.  Depending on the mode, they can operate the system economically; assess the vulnerability of the system; and/or take corrective action in case the system is experiencing failure or is in imminent danger of experiencing failure. All normal and abnormal modes are examined and the operator objectives and tools for each mode are identified.  Case studies of previous real-life notable system failures (blackouts) will also be reviewed; these  reveal how control centers did and did not perform satisfactorily. Finally, likely future trends in control center functions and tools are presented.

Course Topics:

Introduction to Control Center Functions and Tools 

Basics                                  

AC Circuits

Complex Power

Three Phase Systems

Interconnections of Power Systems and power pools (spinning reserve, etc.)

Normal Operating State

Conditions: Constraints met and generation-load balance is maintained

Goal: Operate the power system economically while maintaining the system security

SCADA                                     

Load forecasting                       

Power Flow                              

Real and reactive flow on lines

The Power Flow problem and solution techniques
“Why invert a large matrix”

State Estimation                                             

AGC                                                                          

Economic operation: Energy Market and Deregulation         

Vulnerability Assessment                                          

Steady State Security Assessment

Dynamic Security Assessment

Contingency Selection

Alert State

Conditions: Constraints met, generation-load balance is maintained, but the system is judged to be vulnerable

Goals: Restore system security

Energy supply reserve                                    

Spinning reserve

Equipment limits

Voltage support                                   

Voltage Sags

Reactive power support

Emergency State                          

Conditions: Operating constraints violated but generation-load is maintained

Goals: Restore operating constrains without loss of loads

Reduce line overloads

Use generation reserves

Reroute power supply

Assistance from interconnection, neighbors

Increase reactive power supply

Use local reactive reserves

Assistance from interconnection, neighbors

Failed State (“In Extremis”)

Conditions: Operating constraints violated and generation-load mismatch

Goal: protect equipment, provide power to maximum possible loads at sustainable state

Causes                          

Dynamic instability

Voltage instability

Protection systems                             

Automatic action

frequency based load shedding

Islanding

Continued operation of portion of system

Operator response - Load shedding                

Bulk load shedding

Rolling blackouts

Restorative State                                               

Conditions: Unserved loads;

Goal: to restore the generation-load balance

Partial system - Operating constraints met, load not served

Restart and resynchronize

Blackouts – Case studies                        

New York City – July 1977

Northeastern US – Aug. 2003

Future technologies                                          

Phase measurements

Wide Area Control

Benefits

Participants will understand the responsibility of control center operators for maintaining successful power system operation and for recovering from difficulties due to unforeseen events.  They will learn what the operators’ objectives are in each situation and what management tools the control center provides.  And they will gain an appreciation of the analytical basis for these tools.

Target Audience

· Power system managers who don’t have a power engineering background.

· Electric utility employees who need greater understanding of system operation, e.g. software tool developers, those responsible for power marketing.

· System operators who want greater understanding of the technology.

· Public agency and regulatory staff with responsibility for electric power issues.

· Engineers without a background in power systems

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Jay Giri

AREVA T&D

Redmond, WA