Smart Energy Laboratory (SEL)
Computational Intelligence Applications (CIA) Laboratory

Department of Electrical Engineering
University of Washington


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.

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

Course Topics            

Introduction to Control Center Functions and Tools


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
Load forecasting
Power Flow
Real and reactive flow on lines
The Power Flow problem and solution techniques
Why invert a large matrix
State Estimation
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
Dynamic instability
Voltage instability
Protection systems
Automatic action
frequency based load shedding
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