ERCOT Transmission

1
ERCOT Transmission Decision-Making Study
http//seniord.ee.iastate.edu/Dec0406
Abstract
Project Requirements
The Electric Reliability Council of Texas (ERCOT)
is responsible for monitoring and controlling the
Texas transmission system. ERCOT is interested
in using a probabilistic security assessment
method to determine the security level of the
system for events such as line, generator, or
transformer outages. To provide an assessment of
ERCOTs system risk level, a risk-based security
assessment program will be developed from a set
of MATLAB routines created at Iowa State
University. From the results of the program, an
analysis will be conducted to determine what can
be done to improve the reliability of the
transmission system. Using this program, ERCOT
will be able to take corrective actions to lower
the security risks and improve the reliability of
the transmission system.

• Design Objectives
• Develop useful probabilistic security assessment
  software
• Determine system security in the event of
  component failure
• Functional Requirements
• Software capable of reading ERCOT data
• Evaluate necessary contingencies
• Acceptable execution time

• Design Constraints
• All components adequately modeled
• Software can handle ERCOTs large system
• Measurable Milestones
• Format ERCOT data
• Model incompatible components
• Successfully run security assessment software
  with ERCOT data

Introduction
Proposed Approach and Considerations
Problem Statement Use a probabilistic security
assessment program to determine the security
level of ERCOTs system in the event that a line,
generator, or other piece of equipment
fails Solution-Approach Statement Modify
current risk-assessment software to provide
meaningful insights regarding system security

• Proposed Approach
• Model components to be compatible with software
• Examine contingencies in order to display a
  risk-based security assessment of the system (see
  result visualization in Figure 3)

• Technologies Considered
• MATLAB software
• Parallel processing
• Testing Considerations
• Greater emphasis transmission lines with voltages
  230 kV
• Newton-Raphson method vs. fast decoupled method
  to compute power flow

• Operating Environment
• ERCOT computer network or control center (see
  Figure 1)
• Intended Uses
• Assess power system security risk
• Determine critical system components
• Intended Users
• ERCOT control center employees

Figure 3 Example output of risk-based security
assessment
Estimated Resources and Schedule
Figure 1 Example control center

• Assumptions
• Users computer is capable of handling power flow
  calculations for a system the size of ERCOT (see
  Figure 2)
• Users are familiar with basic probabilistic
  analysis
• Limitations
• Certain components (DC lines, remote voltage
  controllers, etc) will not be explicitly modeled
• The size of ERCOTs system may require
  alternative techniques of analyzing contingencies

Personnel Effort (hours)
Financial Resources
Project Schedule

• Expected End Product
• Software capable of performing risk-based
  security assessment of ERCOT transmission data
• Comparison of traditional and probabilistic
  results

Summary
Figure 2 Texas transmission system
Project Team Information
Closing Summary The Electric Reliability Council
of Texas (ERCOT) desires that a probabilistic
approach be used to assess system security. The
software developed by this team will weigh
higher-risk system components more heavily in
determining actions necessary to maintain system
security. Much effort will be put into
successfully reading data from ERCOTs
transmission system into risk-based security
assessment software. It will also modify the
software to meet contingency and execution time
constraints, while incorporating elements of a
probabilistic method.
Dec0406 Team Members Jacob D. Anderson EE Ryan
M. Link EE James D. McBreen EE Aung M.
Oo EE Christopher L. Storms EE
Faculty Advisor Dr. James McCalley Client H.
Steven Myers, ERCOT Control Center