microprocessor based relaying

8/3/2019 Microprocessor Based Relaying

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Microprocessor-Based Relays:

Implementation, Conflicts, andCorrective Actions

Steven V. Deases

AEP Station Engineer


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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


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Intro: Discussion Focus

Structure: Implementation Strategy Conflicts Encountered

Corrective Actions Topics:

Engineering Processes SCADA Communications

Commissioning Procedures


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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


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Microprocessor Technology

Electromechanical Steady

State

Microprocessor

Evolution of Protection Devices


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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


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Engineering Processes

Engineering Aspects Affected:

Standards

Design

Documentation

Philosophy


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Implementation Strategy:Develop internal Standard Schemes for Protection & Control using

Microprocessor-based Relays that would replace existingElectromechanical Relays and phase them out

These replacement schemes would be designed with a protection zonescope (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


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Documentation:The intent of the documentation was to communicate the standards to

the design groups for implementationApplication 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 philosophyCAD drawings with multiple layers were also developed to match the

standard relay schemes


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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


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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


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SCADA Communications

SCADA Communication Components:

Relay

RTU

SCADA Master


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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


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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


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Corrective Actions:

RTU Point Assignment documentation

Communication Configurations for relays & RTUs delivered by engineering

Training of advanced commissioning techniques

Convert RTUs and Communication Protocol


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HardWired Harris

DNP DNP

DNP Harris


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Commissioning

Commissioning Aspects:

Practices

Procedures

Troubleshooting


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Commissioning

Implementation Strategy:

It was initially assumed that commissioning Microprocessor-based relays was essentiallyvery 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.


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Commissioning


The Black Box phenomena: one device that performs multiple functions with severaldifferent 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 thatof an electromechanical relay scheme


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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


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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