Microprocessor-Based Relays

1
Microprocessor-Based Relays Implementation,
Conflicts, and Corrective Actions
Steven V. Deases AEP Station Engineer
2
Intro Discussion Focus

• Level High-Level Topic Discussion
• Scope Station Protection
• Questions Reserve Questions until the Conclusion
• Time Limitation Approximately 30 minutes total
• Prospective AEPs Experiences

3
Intro Discussion Focus

• Structure
• Implementation Strategy
• Conflicts Encountered
• Corrective Actions
• Topics
• Engineering Processes
• SCADA Communications
• Commissioning Procedures

4
Intro Presenters Background

• Work Group
• AEP Transmission Region Operations Texas
• Technical Support Engineering
• Station Equipment and Protection Controls
• Job Functions
• Application Engineering Design Review
• Technical Aid to Field Personnel
• Project Coordination Administrative Support
• Technical Training of Technicians and Engineers
• Process Improvement Quality Control
• System Performance Analysis Reporting

5
Microprocessor Technology
Evolution of Protection Devices
Electromechanical
Steady State
Microprocessor
6
Microprocessor Technology

• Advantages
• More sensitive and scalable
• Communication Options
• Fault Oscillography and SER data
• Better targeting and annunciation
• More reliable failure alarm also included
• Advanced protection features all in one box
• Economical both Financially and Physically
• Disadvantages
• Shift in Thought Digital Logic v. Circuitry
• More Complex Logical Systems
• Longer Commissioning Procedures
• Additional Training Requirements

7
Engineering Processes

• Engineering Aspects Affected
• Standards
• Design
• Documentation
• Philosophy

8
Engineering Processes

• Implementation Strategy
• Develop internal Standard Schemes for Protection
  Control using Microprocessor-based Relays that
  would replace existing Electromechanical Relays
  and phase them out
• These replacement schemes would be designed with
  a protection zone scope (Line, Bus,
  Transformer, etc.)
• The developed standards defined details such as
• relay brand/model options
• general protection scheme with generic wiring
• relay panel plate configurations
• relay setting templates with predetermined logic

9
Engineering Processes

• Documentation
• The intent of the documentation was to
  communicate the standards to the design groups
  for implementation
• Application Guides were written which described
• What standard schemes were available
• Where the standard schemes were to be applied
• What kind of protection was intended
• The general relay setting philosophy
• CAD drawings with multiple layers were also
  developed to match the standard relay schemes

10
Engineering Processes

• Conflicts Encountered
• Despite the large effort in strategizing the
  implementation process, there still were several
  conflicts encountered
• Perpetual evolution of standards due to newly
  gained experiences
• Design Interpretation of standards resulted in
  inconsistent implementation
• Lack of adequate communication and training of
  standards

11
Engineering Processes

• Corrective Actions
• To combat these engineering problems, we created
  and adopted
• Design Module concept that specifically lays
  out the entire intended design package of
  protection for a specific station application
• E.g. 25MVA Power Xfmr w/ LV CB (Xfmr and LV Bus
  protection included)
• Consistent Relay Setting Calculation Sheets
• Additional Training of how to use these tools and
  the philosophy intent
• Revision control of Standards

12
SCADA Communications

• SCADA Communication Components
• Relay
• RTU
• SCADA Master

13
SCADA Communications

• Implementation Strategy
• Send all potentially necessary data points to
  RTU, then filter which were actually deemed
  necessary for Dispatchers to be sent to the SCADA
  Master
• Let local personnel decide which points the SCADA
  system are needed, configure the devices
  themselves, and commission the data path
• Use existing equipment and communication
  protocols when able

14
SCADA Communications

• Conflicts Encountered
• Inconsistent amounts / types of data being sent
  to Dispatch
• Project Slowdown due to communication discussions
  on every project
• Little documentation of what was implemented
• Confusion regarding data identity due to lack of
  data point naming conventions
• SCADA Alarm Logging was not chronological

15
SCADA Communications

• Corrective Actions
• RTU Point Assignment documentation
• Communication Configurations for relays RTUs
  delivered by engineering
• Training of advanced commissioning techniques
• Convert RTUs and Communication Protocol

16
OLD
Hard Wired
Harris
RTU
Relay
SCADA Master
NOW
DNP
Harris
RTU
Relay
SCADA Master
FUTURE
DNP
DNP
RTU
Relay
SCADA Master
17
Commissioning

• Commissioning Aspects
• Practices
• Procedures
• Troubleshooting

18
Commissioning

• Implementation Strategy
• It was initially assumed that commissioning
  Microprocessor-based relays was essentially very
  similar to commissioning Electromechanical
  relays.
• Test each protection element individually while
  monitoring trip output.
• Technician can create his own test plan based on
  past electromechanical procedures.

19
Commissioning

• Conflicts Encountered
• The Black Box phenomena one device that
  performs multiple functions with several
  different outputs (trips, alarms, targets,
  annunciations, etc.)
• Element Testing vs. Functional Testing
• Those installing the scheme often asked, Whats
  the intent of the design?
• How should the scheme operate for this
  scenario?
• The procedure for troubleshooting a mis-operation
  or failed test is much different than that of an
  electromechanical relay scheme

20
Commissioning

• Corrective Actions
• Commissioning Guides
• Automated Testing Procedures with Pre-determined
  Test Plans
• Design Intent Documents provided with each
  engineered job
• Logic Diagrams matching actual programmed
  internal logic
• New Training Program at New Training Facility

21
Lessons Learned

• Process Improvements
• Re-engineering the process is sometimes needed
• Continual auditing of the process
• Specify Process Feedback Loops
• Identify Experts for Focus Groups
• Defined Time Interval for Revisions to take place
• Quality Control
• Adding quality analysts to team
• Strengthening peer-review ideals
• Workforce Solutions
• Invest in additional engineers, technicians, and
  support staff
• Invest in Training Programs