nerc staff analysis of reported misoperations - final analysis dl/nerc staff an… · nerc | nerc...

NERC | NERC Staff Analysis of System Protection Misoperations | December 2014 I

NERC Staff Analysis of System Protection Misoperations December 2014

NERC | NERC Staff Analysis of System Protection Misoperations | December 2014 i

Table of Contents

Preface ........................................................................................................................................................................ ii

Executive Summary ................................................................................................................................................... iii

Introduction ............................................................................................................................................................... 1

Chapter 1 – Misoperation Data Analysis ................................................................................................................... 2

Misoperation Data Reported ................................................................................................................................. 2

Misoperation Data Reported by Relay Technology ............................................................................................... 3

Chapter 2 – Misoperations Data by Regional Entity ................................................................................................. 5

FRCC Misoperation Analysis ............................................................................................................................... 5

MRO Misoperation Analysis ............................................................................................................................... 6

NPCC Misoperation Analysis .............................................................................................................................. 7

RF Misoperation Analysis ................................................................................................................................... 7

SERC Misoperation Analysis ............................................................................................................................... 8

SPP Misoperation Analysis ................................................................................................................................. 9

TRE Misoperation Analysis ................................................................................................................................. 9

WECC Misoperation Analysis ........................................................................................................................... 10

Chapter 3 – Recommended Actions ........................................................................................................................ 11

Incorrect setting/logic/design errors ............................................................................................................... 11

Communication failures ................................................................................................................................... 11

Relay failures/malfunctions ............................................................................................................................. 12

Overall activities ............................................................................................................................................... 12

NERC | NERC Staff Analysis of System Protection Misoperations | December 2014 ii

Preface The North American Electric Reliability Corporation (NERC) is a not‐for‐profit international regulatory authority whose mission is to assure the reliability of the bulk power system (BPS) in North America. NERC develops and enforces Reliability Standards; annually assesses seasonal and long‐term reliability; monitors the BPS through system awareness; and educates, trains, and certifies industry personnel. NERC’s area of responsibility spans the continental United States, Canada, and the northern portion of Baja California, Mexico. NERC is the electric reliability organization (ERO) for North America, subject to oversight by the Federal Energy Regulatory Commission (FERC) and governmental authorities in Canada. NERC’s jurisdiction includes users, owners, and operators of the BPS, which serves more than 334 million people. The North American BPS is divided into several assessment areas within the eight Regional Entity (RE) boundaries, as shown in the map and corresponding table below.

FRCC Florida Reliability Coordinating Council

MRO Midwest Reliability Organization

NPCC Northeast Power Coordinating Council

RF ReliabilityFirst

SERC SERC Reliability Corporation

SPP‐RE Southwest Power Pool Regional Entity

TRE Texas Reliability Entity

WECC Western Electricity Coordinating Council

NERC | NERC Staff Analysis of System Protection Misoperations | December 2014 iii

Executive Summary The State of Reliability 2014 report found that protection system misoperations continued to be a significant contributor to automatic transmission outage severity1. On average, transmission system events with protection system misoperations were more impactful than other transmission events. They were also, in aggregate, a significant contributor to transmission outage severity, indicating that a reduction in protection system misoperations would lead to an improvement in system reliability. This report focuses on analysis of the top three protection system misoperation cause codes reported on a quarterly basis by the Regions and NERC through compliance with Reliability Standard PRC‐004‐2.1a to identify regional trends and provide guidance to protection system owners that experience a high number of misoperations. Incorrect setting/logic/design errors in microprocessor relays were found to be the largest source of misoperations in almost every region. This further supports that focus should be placed on setting/logic/design controls for microprocessor relays. Specific NERC and industry actions are identified in the report, with the expectation that the rate of misoperations due to these causes can be reduced by 25 percent by yearend 2017.

1 http://www.nerc.com/pa/RAPA/PA/Performance Analysis DL/2014_SOR_Final.pdf

NERC | Polar Vortex Review | August 2014 1

Introduction Protection system misoperations was identified in the State of Reliability 20142 report as an outage cause code that has a significant probability of occurrence and is positively correlated with transmission severity3 when outages do occur. Below are additional findings from analyses of misoperations from 2011 through 2013:

Misoperation occurrences have been consistent over the past three years, with approximately 2,000 misoperations per year.

The rate of misoperations, as a percentage of total operations, has also remained consistent during this period at approximately 10 percent (i.e., roughly one in 10 operations is a misoperation).

The three most common causes of misoperations remain the same (approximately 65 percent of misoperations are caused by incorrect setting/logic/design errors, communication failures, and relay failures/malfunctions).

Three datasets are available to better understand the impact of misoperations on reliability. One dataset is the event reports that are submitted to the Regions and NERC through the event analysis program document4 that was established by the Events Analysis Subcommittee (EAS). When misoperations are associated with reported system disturbances, NERC can then assess their actual impact on the BES and also identify whether they were causal or contributory to the event through cause coding. In 2013, there were 71 transmission‐related system disturbances that resulted in a NERC Event Analysis reported event. Of those 71 events, 47 (about 66 percent) had associated misoperations. Of these 47 events, 38 (about 81 percent) experienced misoperations that were contributory to or exacerbated the severity of the event. In several cases, multiple misoperations occurred during a single disturbance. A second source of misoperations reporting occurs through the TADS data collection. Misoperations that were identified as being caused by human error or relay failure are identified in TADS reporting. This occurs for transmission facilities operated at 200 kV and above. A third source of misoperations reporting is a database of all misoperations that occur on the BES (100 kV and above) that is collected on a quarterly basis by the Regions and NERC through compliance with Reliability Standard PRC‐004‐2.1a. This database provides a comprehensive set of data for all transmission and generation misoperations. It is submitted by the system protection owners and includes detailed information about the misoperation, including a description of the misoperation, its category, its causes, and the proposed mitigation and completion date. This report focuses on analysis of the database of all protection system misoperations that occur on the BES (100 kV and above) that is collected on a quarterly basis by the Regions and NERC through compliance with Reliability Standard PRC‐004‐2.1a. Specifically, analysis was performed on the top three cause codes to identify regional trends and provide guidance to protection system owners that experience a high number of misoperations, with the expected outcome of lowering the overall rate of misoperations throughout North America. This report documents the analysis that NERC staff performed on protection system misoperations and provides recommended action that NERC and industry can take to reduce protection system misoperations and their effect on reliability.

2 http://www.nerc.com/pa/RAPA/PA/Performance Analysis DL/2014_SOR_Final.pdf 3 The severity of a transmission outage is calculated based on its assumed contribution of power flow through transmission circuits. A

description of the calculation is provided in Appendix A of State of Reliability 2014 report 4 http://www.nerc.com/pa/rrm/ea/EA Program Document Library/Final_ERO_EA_Process_V2.pdf

Chapter 1 – Misoperation Data Analysis

NERC | NERC Staff Analysis of System Protection Misoperations | December 2014 2


Misoperation Data Reported Figure 1 shows the misoperation rate by Region as reported in compliance with Reliability Standard PRC‐004‐2.1a. The misoperation rate reflects the ratio of misoperations to total operations for the entire BES, 100 kV and above. This ratio provides a stable way to trend the rate of misoperations, compared to a count of misoperations, where weather and other factors can influence the result. Total protection system operations was first requested with the fourth quarter 2012 misoperation data. Having the total number of operations for the reporting periods in 2013 allows for a consistent way to normalize and trend protection system misoperations over time. Information for WECC is not provided because WECC does not report the total number of operations quarterly.

11.7%

9.6%

18.2%

9.7%

13.9%

7.2%

12.8%

11.4%

7.3%

17.5%

8.9%

14.3%

8.9%

13.0%

10.7%

8.1%

7.6%

9.2%

13.1%

8.4%

12.2%

12.5%

6.3%

11.6%

8.7%

14.2%

6.3%

9.2%

11.4%

10.3%

19.0%

10.9% 13.8%

7.6%

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

14.0%

16.0%

18.0%

20.0%

FRCC MRO NPCC RFC SERC SPP TRE

Misoperation Rate

Region

2012‐Q4

2013‐Q1

2013‐Q2

2013‐Q3

2013‐Q4

Figure 1: Misoperation Rate by Region Figure 2 shows misoperations by month from April 1, 2011, to December 31, 2013. Overall, the trend is periodic, with peaks in the spring and summer months of all three years.



Figure 2: Misoperations by Month (2Q2011–4Q2013)

Figure 3 illustrates the top‐three misoperations cause codes assigned by the Transmission Owners (TOs): incorrect setting/ logic/design errors; relay failures/malfunctions; and communication failures. These three cause codes have consistently accounted for 65 percent of all misoperations since data collection started in 2011.

Figure 3: Misoperations by Cause Code from 2011Q2 to 2013Q3

Misoperation Data Reported by Relay Technology The total misoperations reported for the three years studied was 5774. The collected misoperation data was analyzed by the type of protection system relay technology used: electromechanical, microprocessor, solid state, and communication errors. Figure 4 shows the percentages of the total number of misoperation for the three largest categories of misoperation cause codes for each relay technology type reported. Figure 4 shows that the largest potential focus area for the three main categories of misoperation cause codes studied is incorrect setting/logic/design errors for microprocessor relays, followed closely by communication failures.

277

272 303

247

229

148

152

147

8990 125 143 161

211

201

257

188

143 186

106 145

124

119

127

181 198 228

230

182

154

137

141

133

0

50

100

150

200

250

300

350

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Misoperation Count

2011

2012

2013

29%

21%

15%

12%

8%8%

5% 2%

Incorrect setting/logic/designerrorsRelay failures/malfunctions

Communication failures

Unknown/unexplainable

As‐left personnel error

AC system

DC system

Other/explainable



Figure 4: Misoperations by Relay Technology

Figure 5 below shows the percentages of the total number of misoperations for the three largest categories of misoperation cause codes by voltage class. Figure 5 demonstrates, as did Figure 4, that the largest potential focus area is incorrect setting/logic/design errors.

Figure 5: Misoperations by Voltage Class

15.0

8.87.7

3.53.8

22.0

1.3

0%

5%

10%

15%

20%

25%

Electromechanical Microprocessor Solid State Communication

Percent of Total M

isoperations

Communication failures Relay failures/malfunctions Incorrect setting/logic/design errors

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

<100kV 100kV 115kV 120kV 138kV 161kV 230kV 345kV 500kV 765kV

Misoperations (Percent of Total)



Chapter 2 – Misoperations Data by Regional Entity The reported misoperation data aggregated by Regional Entity is provided in Figure 6. As before, the analysis is focused on the three largest misoperation cause codes (communication failures, relay failures/malfunctions, and incorrect setting/logic/design errors). Misoperations is presented as a percent of total operations in each region. Information for WECC is not provided in this graph because WECC does not report the total number of operations. Figure 6 shows that incorrect setting/logic/design errors were the largest source of misoperations in almost every region. This further supports that focus should be placed on setting/logic/design controls for microprocessor relays.

Figure 6: Misoperations by Regional Entity

The following sections provide protection system misoperation analysis for each NERC Regional Entity. No individual reporting entity within any Region is identified in this report.

FRCC Misoperation Analysis For the three year study period, FRCC reported a total of 186 misoperations. Figure 7 shows the FRCC entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of FRCC total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. It is noteworthy that Entity 1 had a significant number of misoperations due to relay failures/malfunctions compared to the other FRCC entities. Entity 2 had more misoperations due to incorrect setting/logic/design errors than the other cause codes studied. It appears that a focus on incorrect setting/logic/design errors and relay failures/malfunctions could significantly reduce misoperations in the FRCC region.

2.8

3.6

1.9

6.0

3.7

8.7

1.9

7.16.5

3.2

6.3

5.44.9

3.7

5.7

7.1

5.3

8.0

6.4

7.8

7.2

0.0

1.0

2.0

3.0

4.0

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6.0

7.0

8.0

9.0

10.0

FRCC MRO NPCC RFC SERC SPP TRE

Misoperations (%

of Operations in Region)


Chapter 2 – Misoperations Data by Regional Entity


Figure 7: FRCC Misoperations by Entity

MRO Misoperation Analysis The MRO region reported a total of 484 misoperations over the three year study period. Figure 8 provides the MRO entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of MRO total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Notably, Entity 7 and Entity 11 had a significant number of misoperations due to relay failures/malfunctions. Incorrect setting/logic/design errors also appear to be a major contributor to misoperations for many entities in the MRO region. It appears that a focus on incorrect setting/logic/design errors could significantly reduce misoperations in the MRO region.

Figure 8: MRO Misoperations by Entity

9.1

1.60.5

18.3

4.3

0.5

5.4

8.1

3.2

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

Entity 1 Entity 2 Entity 3Misoperations (Percent of FRCC total)


0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Misoperations (Percent of MRO Total)




NPCC Misoperation Analysis The NPCC region reported a total of 601 misoperations over the three year study period. Figure 9 shows the NPCC entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of NPCC total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Entity 4 and Entity 11 had a significant number of misoperations due to incorrect setting/logic/design errors. It appears that a focus on incorrect setting/logic/design errors could reduce total misoperations in the NPCC region.

Figure 9: NPCC Misoperations by Entity

RF Misoperation Analysis The RF region reported a total of 1,189 misoperations over the three year study period. Figure 10 shows the RF entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of RF total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Entity 2 reported approximately 30 percent of all of the RF misoperations reported for the three categories studied. It appears that a focus on incorrect setting/logic/design errors and relay failures/malfunctions could significantly reduce misoperations in the RF region.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Misoperations (Percent of NPCC Total)




Figure 10: RF Misoperations by Entity

SERC Misoperation Analysis The SERC region reported a total of 1,323 misoperations over the three year study period. Figure 11 shows the SERC entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of SERC total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Entity 2 reported approximately 12 percent of all of the SERC misoperations reported for the three categories studied. That entity reported a significant number of misoperations due to relay failures/malfunctions. Entity 2 and Entity 11 reported a significant number of significant number of misoperations due to incorrect setting/logic/design errors.

Figure 11: SERC Misoperations by Entity

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Misoperations (Percent of RF Total)


0.00

1.00

2.00

3.00

4.00

5.00

6.00

Misoperations (Percent of SERC Total)




SPP Misoperation Analysis The SPP region reported a total of 674 misoperations for the three year study period. Figure 12 provides the SPP entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of SPP total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Entity 2 reported 24 percent and Entity 8 reported 22 percent of all of the SPP misoperations reported for the three categories studied. Four entities reported a significant number of misoperations due to communication failures compared with all of the other SPP entities. Entity 2 reported a significant number of misoperations in all three cause codes. Communication failures appear to be a major contributor to misoperations in the SPP region.

Figure 12: SPP Misoperations by Entity

TRE Misoperation Analysis The TRE region reported a total of 401 misoperations for the three year study period. Figure 13 provides the TRE entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of TRE total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Entity 1 reported 27 percent of all of the TRE misoperations reported for the three categories studied. Three entities reported a large number of misoperations due to relay failures/malfunctions. Almost all of the entities reported incorrect setting/logic/design errors as the highest cause code for misoperations. It appears that a focus on incorrect setting/logic/design errors could significantly reduce misoperations in the TRE region.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

Misoperations (Percent of SPP Total)




Figure 13: TRE Misoperations by Entity

WECC Misoperation Analysis The WECC region reported a total of 916 misoperations for the three year study period. Figure 14 provides the WECC entities that had more than 6 misoperations over the three year study period for the three misoperation cause codes analyzed. Misoperations are shown as a percent of WECC total misoperations for the study period. Additionally, only misoperations for the three largest misoperation cause codes are provided. Entity 13 reported 12 percent of all of the WECC misoperations reported for the three categories studied. It appears that a focus on incorrect setting/logic/design errors and relay failures/malfunctions could significantly reduce misoperations in the WECC region.

Figure 14: WECC Misoperations by Entity

0.00

1.00

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8.00

Misoperations (Percent of TR

E Total)


0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Misoperations (Percent of WEC

C Total)


Chapter 3 – Recommended Actions


Chapter 3 – Recommended Actions The 2014 State of Reliability report noted that communication failures, relay failures/malfunctions, and incorrect setting/logic/design errors were the top three causes of relay misoperations. After evaluating the data, incorrect setting/logic/design errors is clearly a priority area for NERC to concentrate its efforts, followed by communication errors and finally, relay failures on electromechanical relays. Below are specific suggestions and quantifiable efforts that address the specific areas to reduce relay misoperation failure rates. The goal is to reduce misoperations due to these three causes by 25 percent by yearend 2017. That would equate to reducing annual misoperations by approximately 325, reducing the overall misoperation rate to about 8%, from 10%.

Incorrect setting/logic/design errors The NERC Protection System Misoperations Task Force issued a report in 2013,5 identifying that misoperations due to incorrect setting/logic/design errors can be reduced by: 1) peer reviews, 2) increased training; 3) more extensive fault studies; 4) standard templates for setting standard schemes using complex relays; and 5) periodic review of existing settings when system topography is changed. Peer review consists of verifying that the relay settings meet the specifications of the relay and control application. When new relays are installed or major changes are made on existing relay schemes, a peer review by a person that has equal or greater experience should be performed to verify that the relay settings meet the specifications of the relay and control application. Increased training will also reduce the calculation and application errors that lead to relay misoperations. The IEEE Power System Relaying Subcommittee, IEEE PSRC, published a working group report to provide additional technical guidance for quality control of protective relay settings.6 Events Analysis has discovered that incorrect ground instantaneous overcurrent settings on the 115‐230kV systems are a leading cause of relay misoperations that lead to a NERC qualified event. NERC is in the process of working with relay vendors and industry participants to create a white paper with some suggestions for both commissioning and testing to uncover limitations in current applications. NERC recommends that NERC and the Regions develop training modules on peer review and the importance of standard design templates to address design and logic settings. Secondly, NERC should work with the Protection System Misoperations Task Force do develop a guideline on quality control of protective relay settings. Finally, NERC should work with relay vendors and industry participants to create a white paper on ground instantaneous overcurrent settings.

Communication failures The design of a protection system involves both balancing dependability and security. Dependability relates to the degree that a relay or relay system will operate correctly (trips when desired). Security is the degree that a relay or relay system will not operate incorrectly (false trip). Recent discussions with engineers from Schweitzer Engineering Laboratories (SEL) has revealed that the design of Power Line Carriers that use Directional Comparison Blocking has caused relays to trip at inappropriate times due to holes in the communication channel7. Studies from SEL have shown that a Directional Comparison Unblocking scheme provides better security (reduces misoperations). This analysis agrees with the work of the Protection System Misoperations Task Force.

5 http://www.nerc.com/comm/PC/Protection System Misoperations Task Force PSMTF 2/PSMTF_Report.pdf 6 “Processes, Issues, Trends and Quality Control of Relay Settings,” Working Group C3 of Power System Relaying Committee of IEEE Power Engineering Society, March 2007.

7 Investigation and Analysis into the Misoperation due to Carrier Holes, John J. Meinardi, Florida Power & Light Co., and Miriam P. Sanders, PE – AMETEK Power Instruments, Copyright 2008.

Chapter 3 – Recommended Actions


NERC recommends the development a webinar, with support from SEL, to inform industry of the Directional Comparison Unblocking scheme solution. NERC and the Regions, in partnership with equipment manufacturers, will develop an industry outreach program that targets specific organizations that can have the greatest impact on communication failure reductions.

Relay failures/malfunctions There are known problems with drift in electromechanical relays, which can be effectively addressed by the following actions:

Reduce maintenance intervals on electromechanical relays with known issues (e.g. KD relays)

Replace these electromechanical relays with microprocessor based relays.

Additionally, some microprocessor based relays are nearing their projected end‐of‐life and are experiencing increased failures. Actively engaging manufactures in proposed solutions will be essential in the foreseeable future. NERC recommends the development of webinar on electromechanical relay maintenance activities. NERC will also reach out to microprocessor relay manufacturers to determine whether any technical bulletins or industry alerts should be developed.

Overall activities NERC is continuing activity on several projects to address protection system misoperations. The Reliability Issues Steering Committee (RISC) has identified system protection issues as one of the top‐priority risks to reliability. NERC has focused its Reliability Standards efforts in this area with the completion of the relay loadability standards and the revised relay misoperation standard. NERC continues its efforts to develop a relay coordination standard. NERC Event Analysis continues to examine system events to identify those that are impacted by protection system misoperations to determine if action is needed to address trends and common modes of misoperations. While the Protection System Misoperations Task Force spent considerable effort developing a report on their investigation, the results have not been actively communicated to industry. This vital information addresses many additional components of relay misoperations. In addition, NERC has historically published Regional misoperations rates with no discussion of comparisons or solutions. Since the Regions have industry experts in committees that regularly discuss relay operations and can implement recommendations, NERC should engage those Regional committees in developing potential actions to reduce misoperations. Finally, the recommendations and findings in this report are consistent with the NATF presentation to the NERC Board in August8. NATF and NERC have begun discussion on co‐hosting a System Protection Misoperation workshop in 2015. NERC will put a spot‐light on the information in the Protection System Misoperations Task Force report for widespread industry distribution. NERC will engage Regional System Protection committees at least twice per year to present Regional misoperation analysis and solicit Regional trends, solutions, and System Protection emerging issues. NERC and NATF will host an industry workshop in 2015 to develop, approve, and reinforce best practices in industry. Further, NERC will support NATF in engaging its membership on these key topical areas of improvement and developing targeted improvement plans.

8 http://www.nerc.com/gov/bot/Agenda highlights and Minutes 2013/bot_presentations_August_2014.pdf

nerc staff analysis of reported misoperations - final analysis dl/nerc staff an… · nerc | nerc...

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