Remedial Action Schemes
Maintain System Stability Using Proactive Controls and Contingency-Based Actions
Protect Against Blackouts
Increase Reliability With a
Robust, Multifunction System
Increase Corridor Capacity Limits
and Operate Closer to Stability Limits
Monitor System Diagnostics
Integrate Into Existing Systems
Making Electric Power Safer, More Reliable, and More Economical ®
www.selengineering.com
+1.509.332.1890
info@selengineering.com
Maintain Stability With SEL Remedial Action Schemes
SEL remedial action schemes (RAS) detect abnormal conditions in your power system and take automatic corrective actions. The SEL
proprietary control system provides system stability using proactive controls and contingency-based actions. SEL engineers have the
knowledge and experience to integrate these schemes into your current system. The SEL solution has flexible communications channels
and device options.
Example: A bus coupler opening will create a load deficit on one island and a generation deficit on the other island. Prevent
this condition by actively controlling the tie flow. If the breaker opens under flow, then load and/or generation shedding can
immediately correct for the disturbance.
Automatically Respond to System Contingencies
Detect and automatically respond to multiple, consecutive system contingencies. Control thousands of contingencies and loads with high-speed
Mirrored Bits® communications or IEC 61850 GOOSE messages. Preserve system stability using intelligent, contingency-based actions, such as
flexible load and generation shedding. All loads/generation are prioritized and shed only when necessary to satisfy the contingency. Detect
unstable power conditions and automatically take corrective action, such as system islanding, to avoid blackouts.
Possible Actions
Contingencies
Island
Detected
Generation
Dropped
Intertie
Loss
Load Shedding
X
X
X
Generation Shedding
X
X
Load
Dropped
System
Instability
X
X
X
X
System Islanding
Series Capacitor Bypass
X
X
X
X
X
Shunt Capacitor/Reactor/Resistor Insertion
X
X
X
X
X
DC Tie Runback
X
X
X
X
X
Avoid System Disturbances With Proactive Controls
SEL schemes proactively control your equipment to prevent system collapse. SEL RAS provides control of dc ties, static and synchronous condensers, generator field exciters and governors, and flexible ac transmission systems (FACTS) to place system operating conditions at an optimal
operating point to withstand major system disturbances.
System Strategies
Power Factor
Control
Voltage
Management
Raise/Lower Controls
DC Ties
Frequency
Management
Intertie Flow
Control
X
X
Load
Sharing
Static/Synchronous Condensers
X
X
X
X
Generator Field Exciters
X
X
X
X
Generator Governors
X
X
FACTS
X
Quickly and Easily Analyze Events
An HMI provides online monitoring of pertinent control
system parameters. The system has the ability to show
a detailed history of alarms, errors, and failovers. SEL
software displays oscillograms and vector diagrams to
accelerate event report analysis.
• HMI and SCADA alarms
• Sequence of events (SOE) logging and viewing
• Event reports (oscillography of events)
Event reports are created every time a
contingency is triggered.
Example system-wide sequence of events record viewer.
Remedial Action Schemes
Maintain System Stability Using Proactive Controls and Contingency-Based Actions
Monitor System Status and Easily Tune Settings
SEL RAS provides a full engineering interface for system tuning, system diagnostics, and device diagnostics.
Example device diagnostics screen.
Example system diagnostics screen.
Example system tuning screen.
Complete Testing and Simulation
SEL thoroughly simulates and evaluates, under real-world conditions, all remedial action schemes. This testing eliminates many unforeseen
complications before bringing the system online. All systems are heavily reviewed and tested at all phases of system design, manufacture, and
final validation. During final validation testing, SEL creates one or both of the following systems:
Static Simulation System — This system simulates real-world I/O, relays, and communications processing equipment. It generally consists of a single rack of equipment, which
communicates directly with the RAS system. Testers input data onto an HMI screen, and
it is propagated to the system under test. The Static Simulation System is available for
purchase for enhanced training and on-site simulation of system performance.
Dynamic Simulation System — This system provides for closed-loop system testing
using a real-time digital simulator (RTDS®). All system dynamics are fully simulated, including governors, exciters, transformers, motors and loads, capacitor banks, and more.
This testing is completed at the SEL factory, and its completion allows the RAS system to
“plug and play.”
Implement SEL remedial action schemes today. Contact SEL to find out how we can work with you.
Making Electric Power Safer, More Reliable, and More Economical ®
© 2008 by Schweitzer Engineering Laboratories, Inc. 20080430 • PF00176
www.selengineering.com
+1.509.332.1890
info@selengineering.com