EMS
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
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