Remedial Action Schemes (RAS) - Washington State … Action Schemes (RAS) Presented by Brant Heap Salt River Project Hands-On Relay School March 19 th, 2014 2 Overview What is a RAS

Remedial Action Schemes (RAS)Remedial Action Schemes (RAS)

Presented by

Brant HeapSalt River Project

Hands-On Relay School

March 19th, 2014

2

OverviewOverview

What is a RAS

Why are RASs Needed?

RAS Classifications and Types

Composite of a RAS Scheme

RAS Design

RAS Testing

RAS Scheme Review

RAS Examples

3

What is a RAS?What is a RAS?

Synonymous Acronyms

RAS – Remedial Action Scheme (WECC)

SPS – Special Protection Scheme (NERC, others)

SIPS – System Integrity Protection Scheme (IEEE)

Automatic protection system designed to detect abnormal

predetermined system conditions and takes a predefined

action to prevent a system problem

Take corrective actions other than and/or in addition to the

isolation of faulted components to maintain system

reliability

4

What a RAS is not?What a RAS is not?

Fault conditions that must be isolated with standard

relaying schemes

Underfrequency or Undervoltage Load Shedding

Out of Step Relaying that is not an integral part of a RAS.

Sub-synchronous resonance (SSR) protection schemes.

Auto reclosing schemes

5

RAS or Other Alternative?RAS or Other Alternative?

Responds to low probability events in the system

Increases path capacity without building more

power lines

A $1m RAS in place of a $50-$200m transmission line

Operating transfer capability on a path could quadruple

with a RAS

Helps balance load and generation after a loss of

one or the other

Increases overall system reliability

Meet project schedules

6

What is a RAS SummaryWhat is a RAS Summary

RAS schemes are implemented to solve single and credible multi-

contingency problems not protected by standard equipment

protection.

Major applications of RAS include:

Increasing power transfer

Add reactive support

Limit scale of cascading outages

RAS schemes address specific pre-determined problems such as:

Equipment overloads, Low voltages, Unstable generation , and unstable

load.

RAS CLASSIFICATIONS

AND

TYPES

RAS CLASSIFICATIONS

AND

TYPES

7

8

Wide Area Protection Scheme (WAPS)

Local Area Protection Scheme (LAPS)

Safety Net (SN)

9

Wide Area Protection Scheme:

WAPS

Wide Area Protection Scheme:

WAPS

Wide Area Protection Scheme (WAPS): A Remedial Action

Scheme whose failure to operate WOULD result in any of the

following:

Violations of TPL – 001-WECC-RBP-2 System Performance RBP

Maximum load loss ≥ 300 MW

Maximum generation loss ≥ 1000 MW

Wide Area RASs require higher reliability requirements and a more

thorough review from WECC RASRS subcommittee as compared to

Local Area and Safety Nets

Meets WECC’s performance requirements.

Local Area Protection Scheme:

LAPS

Local Area Protection Scheme:

LAPS

Local Area Protection Scheme (LAPS): A Remedial Action Scheme

whose failure to operate would NOT result in any of the following:

Violations of TPL – 001-WECC-RBP-2 System Performance RBP

Maximum load loss ≥ 300 MW

Maximum generation loss ≥ 1000 MW

LAPS scheme will be reviewed by the RASRS for classification only.

Meets owner’s performance requirements with owner’s system.

10

Safety Net: SNSafety Net: SN

Safety Net: A Remedial Action Scheme designed to remediate TPL-

004-0 (System Performance Following Extreme Events Resulting in

the Loss of Two or More Bulk System Elements (Category D)), or

other extreme events.

Remediation of extreme events is not required by NERC or WECC.

An optional, extreme event remediation scheme is a RAS and classified as a

Safety Net

A scheme used to provide a defense against extensive cascading or complete

system collapse.

11

WECC Remedial Action Scheme

type definitions.

WECC Remedial Action Scheme

type definitions.

12

Event-based

Directly detect outages and/or fault events and initiate actions.

Parameter-based

Measure variables for which a significant change confirms the

occurrence of a critical event.

Response-based

Monitor system response during disturbances and react to actual

system conditions.

13

Types of RASTypes of RAS

14

Local RAS ExampleLocal RAS Example

A RAS trips 400 MW of generation to relieve a thermal line

overload following a single contingency.

• The WECC TPL RBP doesn’t mention thermal overloads,

so this criterion does not apply here,

• The maximum load loss is less than 300 MW, and

• The maximum generation loss is less than 1000 MW.

This scheme is a LAPS because it remediates a single

contingency (no SN), WECC TPL RBP doesn’t apply, and

generation and load loss levels are below those trigger levels

15


Wilder

Landon

Walnut Grove

Ingalls

500kV

500kV

500kV

345kV

Unit 1 online

Unit 2 online

Bypass Series Caps

500kV

With series capacitors installed on the Landon-Walnut Grove line, there is a concern of SSR problems on the generators if radial. Local RAS scheme in place to bypass series capacitors if generating while radial.

Is this event or

parameter based?

16

Wide Area RAS ExampleWide Area RAS Example

OREGON

COI

California/Oregon

Inter-tie (Path 66)

Palo Verde

Nuclear Generating

Station

Phoenix

ARIZONA

CALIFORNIA

•Loss of 2 units at Palo Verde while running above

2550MW would cause instability to the Calif/Oregon

Inter-tie (COI)

•Required load shed of at least 120MW to mitigate

17

QuestionQuestion

Studies show that the failure of the A RAS would result in the loss of

300MW of load and 900MW of generation. The studies also show there

are no Violations of TPL – 001-WECC-RBP-2 System Performance RBP.

Is this RAS a LAPS or WAPS?

COMPOSITE OF A RASCOMPOSITE OF A RAS

18

19

Composite of a RAS SchemeComposite of a RAS Scheme

Problem to Mitigate

The issue that needs to be reduced or eliminated.

Arming Condition

Permissive for RAS to operate.

Trigger Condition

Causes the scheme to operate if armed.

Operate

What the Scheme does to mitigate the problem.

20

Problem to mitigate Arming Condition

21

Problem to MitigateProblem to Mitigate

RAS are generally designed to mitigate three types of power

system problems and time scales:

• Thermal (minutes)

• Voltage Stability (seconds to minutes)

• Transient Stability (cycles to seconds)

22


Thermal Overload (Fast: seconds or minutes)

Result from excessive currents flowing through transmission

circuits caused by heavy loads

Can cause overheating, line sags, and loss of conductor

strength

These RAS schemes can take sec/min rather than a few cycles

Examples of mitigation include backing generation or load

shedding

23

When a line loaded above it’s Surge

Impedance Level (SIL), it acts like a

shunt reactor absorbing Mvars. This

pulls the voltage down and puts the

system at risk of a voltage collapse.

The reactance causes voltage problems

before resistance heating causes thermal

problems.

Examples of mitigation include shunt

cap insertion or gen drop


Voltage Instability (faster: cycles or seconds)

24

Transient Instability (fastest: 8-30 cycles)

Disturbance which does not allow a generator to deliver its

power into the network. (i.e. sudden line outages)

Power then absorbed by generator resulting in sudden

acceleration of the rotor and eventually cause damage of the

generator

Examples of mitigation include fast gen drop or use of

braking resistor


The permissive for a RAS to operate. We typically arm a

RAS based on changes in critical system conditions.

25

Arming ConditionArming Condition

Line out of Service

Generation Output

Line Loading

Trigger ConditionTrigger Condition

The trigger condition is what initiates the Operation actions.

Like the Arming condition, the Trigger condition is often a

change in or loss of a critical system.

26

Loss of GenerationLoss of Line

OperateOperate

What actions the Scheme takes to mitigate or prevent the

problem.

27

Cap Insertion

SWT

BKR

Cap Bypass

Load Shed

Gen Drop

RAS Composite OverviewRAS Composite Overview

28

RAS

Problem

Thermal

Voltage

Transient

Arming

Line Loading

Gen Output

Line OOS

Trigger

Line Loss

Generation Generation Loss

Operate

Cap Insert

Cap Bypass

Gen Drop

Load Shed

29


Wilder

Landon

Walnut Grove

Ingalls

500kV

500kV

500kV

345kV

Unit 1 online

Unit 2 online

Bypass Series Caps

500kV

Problem to Mitigate: SSR concerns when generating radial with series compensation in service.

Arming Condition: Series Compensation in service.

Trigger Condition: Loss of Landon- Ingalls line OR los of Wilder-Landon line.

Operate Condition:Bypass series compensation.

30

RAS Example 1RAS Example 1

Desert Basin 230kV

Casa Grande 230kV

Saguaro 230kV

Santa Rosa 230kV

Casa Grande – Saguaro 230kV line

Initially out of service (IOS)

To Tatmomli

To Knox

To TesttrakCasa Grande 69kV

Santa Rosa 69kV

Fault occurs on DBG-

Santa Rosa 230kV line

The only outlet for DBG

generation is 100MVA Casa

Grande 230/69kV transformer

Problem to Mitigate

•Voltage dip at DB 230kV bus

and neighboring busses

•Casa Grande 230/69kV

transformer overload

Thermal & Voltage Instability

31


GR

OS

S D

BG

OU

TP

UT

TH

RE

SH

OL

D (

MW

)

TERMINAL VOLTAGE (kV)

585

630 630

550558

567575

583

543535

525

465

510503

517

630627620

613607

600

590

576570

535

465

485

505

525

545

565

585

605

625

645

0.975 0.98 0.985 0.99 0.995 1 1.005 1.01 1.015 1.02 1.025 1.03 1.035 1.04 1.045 1.05

RAS Armed CT1 trip CT1&CT2 trip

1.042

583

18 18.3618.2718.1818.09 18.6318.5418.45 18.8118.72 18.917.64 17.73 17.82 17.9117.55

NOT ARMED

REGION 1CT1 or CT2 ARMED TO TRIP

REGION 2CT1 and CT2 ARMED TO TRIP

Arming Condition

32

ARMED SIGNALTO SEL321 RELAY

DCS

TOTAL MWSIGNAL

TERMINALVOLTAGESIGNAL

PLC

GENERATING INOPERATING REGION


33

Santa Rosa Line


ARMED SIGNALFROM PLC

SEL321 Relay

LOCKOUT

OUTPUT

CT1

CT1GEN BKR

CT2

CT2GEN BKR

SELECTOR SWITCHCT2

CT1

&

CT2

CT1

&

CT2

CT1

Trigger Condition

•Fault on the Santa Rosa Line

Operate – Method of Mitigation

•Gen Drop

Trigger & Operate

34

Average Time Elapsed fromSanta Rosa Line Fault to Generator Breaker Trip:

RAS A = 5.8 cyclesRAS B = 6.0 cycles

Indicates Timing Test Verified

T = 01.5 62.5

Time in Cycles

Timing Test Results


DESIGN COMPONENTSDESIGN COMPONENTS

35

36

Design Components OverviewDesign Components OverviewLogic

Logic diagrams, timing diagrams, flow charts, etc.

RAS Controllers

Relays, PLCs, DCS

Detection and Initiating Devices

Sensing

CTs/PTs, Transducers

Input/Outputs

Breaker status, trip coils, control outputs, etc.

Communications

High reliability

High availability

Appropriate timing

Monitoring and Alarms

Equipment self diagnostics, telecom., RAS actions, etc.

Redundancy, Redundancy, Redundancy!

LogicLogic

37

Detailed logic documentation is KEY to a successful RAS design and implementation.

Logic documentation comes in many forms such as, flow charts, written descriptions,

equations, timing tables, and logic diagrams.

Scheme logic will direct the design, aid in reviews, assist operating personnel, and provide

support for testing and troubleshooting the scheme.

Logic can become very complex and should be designed to maximize reliability, minimize

complexity, allow safe scheme testing, and allow for easy modifications.

38

Logic Chart: Arming AlgorithmsLogic Chart: Arming Algorithms

Logic Diagram ExamplesLogic Diagram Examples

39

ARMED

LOSS OF LINE 1

RAS Armed

LOSS OF LINE 2

LOSS OF LINE 3

UNIT TRIP LOGIC

TRIP TEST

RAS IN TEST

10cy

4ms

Timer 14

pu = 4ms

do = 10cy

Test Logic

LLL

LLL

LLL

TRIP PB

IN TEST

Communication Failure

Trip/Operate Logic

RAS ControllersRAS Controllers

Microprocessor Relay

40Distributed Control System (DCS)

Programmable Logic Controller

(PLC)

RAS controllers come in many different forms

Things to consider when selecting a RAS controllerComplexity of scheme logic and processing requirements

Reliability

Availability

Functionality

Maintainability

Familiarity with maintenance personnel

Expandability

Detection and Initiating DevicesDetection and Initiating Devices

Detection and initiating devices are the link between the field

and RAS controller. Some provide real time system

conditions for accurate logic processing while others securely

perform actions when requested.

• Some of their purpose are to provide, line open status,

generation output, line loading, and etc.

41


Sensing Equipment


Sensing Equipment

Transducers

42

Current Transformers (CTs) Potential Transformers

(PTs,CCVTs)

• Voltage• Current• Power• Frequency


Inputs and Outputs


Inputs and Outputs

43

Disconnect StatusControl Inputs

• Breaker status• Disconnect status• Breaker trip bus monitoring

• Manual arming• Local/remote disabling

Detection and Initiating DevicesDetection and Initiating Devices

Detection and initiating devices need to be secure and

reliable.

Several devices are often needed in combination to provide

accurate and secure indication.

A good example of this is ‘line open detection’. To

determine the correct status of a line we may need inputs

form several devices:

Breaker status

Disconnect status

Undercurrent detection

Breaker trip bus monitor

44


Loss of Line Examples



45

BKR1 BKR2 BKR3 BKR4

Protected Line

Line Loss Logic (LLL): Breaker Status





46

BKR1 BKR2 BKR3 BKR4

Protected Line

Line Loss Logic (LLL): Trip Coil Energized

Often used to increase speed of RAS operation.

CommunicationsCommunications

47


48

RAS are highly dependent on high-speed telecommunications.

Communication channels must meet at least the same criteria as other relaying

protection communication channels.

The scheme logic must be designed so that loss of the channel, noise, or other channel

failure will not result in a false operation of the scheme.

All channel equipment must be monitored and alarmed to the dispatch center so that

timely diagnostic and repair action shall be take place upon failure.

Leased telephone circuits or pilot wire circuits on power system structures will most

likely lead to unreliable operations. Such channels shall only be used when no other

communications media are available. Automatic channel testing and continuous

monitoring are required if telephone leased lines are used.


49

RAS scheme communications must have high Reliability, Availability, adequate

Redundancy, and appropriate Timing.

Reliability: the assurance that the system operates correctly. It will respond when

intended and restrain when not intended (…Dependability and Security)

Availability: how often is the system functioning at or above its required performance

level.

Redundancy: this helps improve the availability as well as allow for maintenance.

Communication system Timing: how long it takes for the communication system to

receive the packet from the device, transmit the packet across the network, and transfer

the packet back to the device. (…note that the complete End-to-End timing must also

consider the relay detection time, encoding time, device operation time, etc.)


50

End-to-End Delay


51Typical RAS Functions with Availability References

Monitoring and AlarmsMonitoring and Alarms

52

Minimum Monitoring Should Include

Arming status

Initiating device operation

Telecommunications

Tripping device operation

Status of operation or test switches

Equipment self-diagnostics and annunciation

Indication when a manually armed scheme should be armed or may be disarmed.

The monitoring of a RAS scheme is crucial.

All critical alarms and indication shall have adequate time stamping and be

made available to system operators.

RAS failures typically require system operators to adjust the transmission

system. This often requires the reduction of flow on major paths and

backing of generation.

Redundancy, Redundancy, Red…Redundancy, Redundancy, Red…

53

RAS redundancy requirements are similar to

the requirements for other protection

systems.

Redundancy is intended to allow removing

one scheme following a failure or for

maintenance while keeping full scheme

capability in service with a separate scheme.

Redundancy requirements cover all aspects

of the scheme design including:

Detection, arming, power supplies,

telecommunications facilities and equipment,

logic controllers (when applicable), and RAS

trip/close circuits.

54

Design Components ReviewDesign Components ReviewLogic

Logic diagrams, timing diagrams, flow charts, etc.

RAS Controllers

Relays, PLCs, DCS


Sensing

CTs/PTs, Transducers

Input/Outputs

Breaker status, trip coils, control outputs, etc.

Communications

High reliability

High availability

Appropriate timing

Monitoring and Alarms

Equipment self diagnostics, telecom., RAS actions, etc.

Redundancy, Redundancy, Redundancy!

RAS Controller SchematicRAS Controller Schematic

55

BKRStatuses

Control

InputsRemote/Local

Trip Coil Monitors

MonitoringRemote/Local

Local Control

Switch.Normal, Disable, &

Test

Relay Contact Chart

Panel Layout ExamplePanel Layout Example

RAS A

RAS B

Disable

Switches

56

LOCKOUTS

SELECTORSWITCHES

TESTSWITCHES

FT-19CUTOFF BLADES


RAS A Currents

& Potentials

RAS A Currents

& Potentials

RAS B DCRAS B DC

RAS B Control,

Alarms, Status

RAS B Control,

Alarms, Status

RAS B Currents

& Potentials

RAS B Currents

& Potentials

All cables redundant

Power supply fusing

redundant

RAS A wiring on

one side of panel,

RAS B wiring on the

other

RAS A DCRAS A DC

RAS A Control,

Alarms, Status

RAS A Control,

Alarms, Status


RAS ARAS A

RAS BRAS B


Three-lineThree-lineThree-lineThree-line

61

Commissioning and Maintenance

Testing

Commissioning and Maintenance

Testing

Acceptance Checks

Verify the functionality of the relay inputs/outputs

Scheme Checks

Verify the wiring and all new physical connections to

controllers/relays

Verify operation of lockouts when trip outputs are initiated

Logic Testing

Verify operation of relay settings and logic of each relay

End-to-end Testing

Verify data transfer between relays

Initiate trigger condition and verify operation

Verify timing requirements are satisfied.

62

RAS Scheme WECC ReviewRAS Scheme WECC Review

Remedial Action Scheme Reliability

Subcommittee (RASRS)

Originally a task force in 1985

In 2005, task force was designated a subcommittee

reporting to WECC

Committee consists of knowledgeable representatives

from several region utilities with backgrounds in

communication, automation, planning, operations, and

relaying.

Reviews the RAS designs to ensure reliability and no

single points of failure that would result in Bulk

Electric System performance outside of WECC

performance limits

63

RAS Scheme WECC ReviewRAS Scheme WECC Review

When is RAS Review Required?

Prior to initial installation and commissioning.

Before significant modifications.

Removal of the scheme from service.

More RAS Scheme ExamplesMore RAS Scheme Examples

64


System Changes

Addition of new generating unit at Longhorn

Potential Conditions

Overload of path 4

Post-transient voltage stability

65

66

Fredette

BuckeyeCougar

Jayhawk

345kV 500kV

Unit 1

Unit 2

Problem to Mitigate: Thermal overload on Path 4 and voltage

stability problems on neighboring busses

Arming Condition: Load on Buckeye-Jayhawk line exceeds

800MW

Trigger Condition: Loss of Buckeye-Jayhawk Line

Operate Condition:•Insert shunt cap within 10 cycles

•Trip Buckeye Unit 1 within 60 cycles

Longhorn

345kV500kV

Shunt Cap

Irving Substation

Thermal & Voltage Instability


67

Reclosing SummaryReclosing Summary

Avoid tripping generation at Buckeye if fault is momentary

Reclosing added on Buckeye-Jayhawk lineBU932, BU935

JH932, JH935

Reclosing can be enabled/disabled locally or remotely

Reclosing is in-service if…Reclosing is enabled

RAS is armed

Breaker is initially closed

5 minutes has elapsed since last reclose

Jayhawk will reclose first 35cy after fault inception

Buckeye will reclose 55cy after fault inception only if reclose was successful at Jayhawk

Reclose only has 1 shot per fault


68

Reclosing OperationReclosing Operation

Jayhawk

Unit 1

JH932

Buckeye

JH935 BU935 BU932

Initial Conditions:•Reclosing enabled on JH932 and BU932•RAS is Armed•79RB In-service = RAS Armed and Reclosing Enabled

79RB Enabled 79RB Enabled

79RB In-service 79RB In-service

Operation Scenario 1 (momentary fault):1. Fault occurs on BU-JH line2. All breakers associated with line open3. After 35 cycles from initial fault, JH932 recloses successfully4. After 55 cycles from initial fault, BU932 recloses successfully5. Unit 1 at Buckeye is not tripped (High speed caps still insert)6. RAS remains armed

RASArmed


69

Reclosing Operation (cont’d)Reclosing Operation (cont’d)

Jayhawk

Unit 1

JH932

Buckeye

JH935 BU935 BU932

Initial Conditions:•Reclosing enabled on JH932 and BU932•RAS is Armed•79RB In-service = RAS Armed and Reclosing Enabled

79RB Enabled 79RB Enabled

79RB In-service 79RB In-service

Operation Scenario 2 (sustained fault):1. Fault occurs on BU-JH line2. All breakers associated with line open3. After 35 cycles from initial fault, JH932 recloses into fault4. JH932 trips5. BU932 never attempts to reclose6. After 55 cycles from initial fault, Unit 1 at Buckeye is tripped 7. RAS disarms

RASArmed


70


Shunt Cap Overview

230kV Shunt caps at 2 sites may be used.

Breakers are used for high speed insertion

Shunt cap at IR is used for RAS exclusively.

Shunt cap at CRABB is normally used for voltage control

but can be switched to be used for RAS under certain

circumstances. Cap must be configured by Operations for

high speed insertion for use in RAS.

71


Irving

SWT

BKR IR658

IR655

Crabb

SWT

BKR CRB618

CRB615

• Crabb cap bank is typically used for operational voltage control but may be configured for use in RAS.

Shunt Cap Normal

Operation

72


Irving

SWT

BKR IR658

IR655

Crabb

CRB618

CRB615SWT

BKR

Operation Scenario (Irving is “Not Available”):1. Operations receive IR Cap Bank Not Available alarm2. Operations make Crabb available for high speed by opening CRB618 and closing CRB6153. Dispatch personnel to Irving to troubleshoot problem4. Once alarm at Irving is clear, switch back to normal

SWT

BKR

IR Cap

Bank

Not Avail

Shunt Cap at KI or

IR “Not Available”

73Example RAS Communication Network


MAIN N60

RAS1

MAIN N60RAS2

MAIN N60RAS3

MAIN N60MISC

C70 ARAS2

C70 BRAS1,2

C70 CRAS1,2

C70 DRAS1,2

ETHERNET

LAN

N60 ARAS1,2,3

N60 BRAS3

N60 CRAS2

N60 ERAS1,2

N60 GRAS3

G.703

N60 FRAS1,2,3

N60 DRAS2,3


Example RAS Simplified Communication Network

• Bandwidth to meet time constraints

• Low data error

• High availability

• Relays can exchange data with any other

relay in its network or ring

75


Relay Fail – Relay is failed or communication has failed and relay will not function as designed

Relay technician should be dispatched to diagnose problem

Communication technician may need to be involved as well

Diminished RAS – RAS is still operational, but is one condition away from being non-operational

Direct Ring break causes this alarm and System Protection should be contacted to find location of break

RAS Disabled – RAS is disabled either locally or by SUPY

RAS in Test – RAS system has been placed in “test” at site and is non-operational

RAS Armed – RAS system is armed and will operate under the required trigger conditions

RAS Operated – At least one component of the RAS has operated successfully

Dispatcher should follow recovery procedure

Alarm/Status Summary & Response

Utility C

76

+

1 2

Fredette

BuckeyeCougar

Jayhawk

345kV 500kV

Longhorn

345kV

500kV

Shunt Cap

Irving

RAS Example 2: Big PictureRAS Example 2: Big Picture

77

78

• A new 600MW unit was installed at Phoenix Generating Station (PGS).• Due to the added generation, series capacitors were installed on the

transmission system to increase the path operating capabilities. • New studies were performed modeling the additional generation and line

capacities. The studies identified several system configurations that would

result in transient instability violations and possible damage to the PGS units.• The Phoenix RAS was designed to mitigate the adverse effects of the added

generation and line capacities in lieu of building an additional 300 mile line.

79

Mesa500kV

Unit 1

Gilbert500kV

Unit 2

Scottsdale500kV

Unit 3

Phoenix

PhoenixGenerating

Station

600MW

600MW

600MW

New Series Capacitors

New 600MW Unit

RAS Example 3

ARM

Problem to Mitigate: Transient angle instability at Phoenix will cause

Phoenix Generating Station to go out-of-step and trip off line.

Arming Condition 1: Series capacitors bypassed on Mesa/Phoenix line

and Gilbert/Phoenix line and PGS >= 1050MW.

Trigger Condition 1: Loss of Phoenix/Scottsdale line

Operate Condition 1:•Trip Unit 3 within 15 cycles

80

Mesa500kV

Unit 1

Gilbert500kV

Unit 2

Scottsdale500kV

Unit 3

Phoenix

PhoenixGenerating

Station

600MW

600MW

600MW

ARM

TriggerOperate

RAS Example 3-1

ARM



Arming Condition 2: Series capacitors bypassed on Scottsdale/Phoenix

line and Gilbert/Phoenix line and PGS >= 1050MW.

Trigger Condition 2: Loss of Mesa/Scottsdale line

Operate Condition 2:•Trip Unit 1 within 15 cycles

81

Mesa500kV

Unit 1

Gilbert500kV

Unit 2

Scottsdale500kV

Unit 3

Phoenix

PhoenixGenerating

Station

600MW

600MW

600MW

ARM

Trigger

Operate

RAS Example 3-2



Arming Condition 3: Mesa/Phoenix line IOS and PGS >= 800MW.

Trigger Condition 3: Loss of Phoenix/Scottsdale line or loss of

Phoenix/Gilbert Line

Operate Condition 3:•Trip 2 units off within 20 cycles.

82

Mesa500kV

Unit 1

Gilbert500kV

Unit 2

Scottsdale500kV

Unit 3

Phoenix

PhoenixGenerating

Station

600MW

600MW

600MW

RAS Example 3-3

• The Phoenix RAS is dynamic and automatically selects and trips units based on which

line goes out of service.

• At times, Operations wants the ability to select which units trip offline.

• Under certain circumstances this is ok but must be done with caution to avoid tripping to

black plant

83

Mesa500kV

Unit 1

Gilbert500kV

Unit 2

Scottsdale500kV

Unit 3

Phoenix

PhoenixGenerating

Station

600MW

600MW

600MW

PHX11 PHX12 PHX13

PHX21 PHX22 PHX23

PHX31 PHX32 PHX33

PHX41 PHX42 PHX43

Lets consider our previous example of RAS-3 but this time we will have PHX12 out on maintenance and Unit 2 manually selected to trip

RAS Example 3-4

Exercise: University LAPSExercise: University LAPS

WSU

ORE USC

ASU

University Generating Station

230kV

230kV 230kV 230kV

230kV

12 Units 50 MW each

Total = 600 MW

More than 4 units are online

The only outlet is

through USC’s 69kV

system.

Fault occurs on the

WSU/ASU line and

WSU/ORE line

…or a fault occurs on the

WSU/ASU line and ORE/USC line

All but 4 units trip offline within

15cycles.

Without University LAPS installed.

With University LAPS Installed

Study Results

Exercise: University LAPS


What is the problem to mitigate?Voltage dip at ASU 230kV bus and neighboring busses

Thermal overloads on neighboring 69kV lines out of USC

What is the arming condition?More than 4 generators on line

What is the Tripping condition?Loss of ASU/WSU line and loss of either WSU/ORE or ORE/USC line

What are the operating actions?

Trip all but 4 generators off line with 15cycles.

86


87

UNIT TRIP LOGIC

10cy

4ms

ARMEDLLL

ASU/WSU

LLL

WSU/ORE

LLL

ORE/USC

Using the Trigger conditions create the Operate logic (unit trip logic) using the information

shown below.


88

WSU ORE USC ASU

WSU11

WSU10 ORE10 ORE20 USC20USC10

ASU21

ASU20ASU10

LINE 1 LINE 2

LINE 3

LINE 1 LINE 2

Now that we have the Operate logic, lets create the Line Loss Logic and Arming Logic.

Use only 52b status and Trip Coil Monitor.

WSU20


89

WSU ORE USC ASU

WSU11

WSU10 ORE10 ORE20 USC20USC10

ASU21

ASU20ASU10

LINE 1 LINE 2

LINE 3

LINE 3

Now that we have the Operate logic, lets create the Line Loss Logic and Arming Logic.

Use only 52b status and Trip Coil Monitor.LOSS OF LINE

10cy

Timer 2

pu = 0cy

do = 10cy

0cy

10cy

Timer 3

pu = 0cy

do = 10cy

0cy

10cy

Timer 4

pu = 0cy

do = 10cy

0cy

10cy

Timer 5

pu = 0cy

do = 10cy

0cy

WSU20

90

QUESTIONSQUESTIONS

Is my lanyard

connected?

Documents

Remedial Action Schemes (RAS) - Washington State … Action Schemes (RAS) Presented by Brant Heap Salt River Project Hands-On Relay School March 19 th, 2014 2 Overview What is a RAS