SPP 2015 TPL-001-4 STABILITY ASSESSMENT
SPP 2015 TPL-001-4STABILITY ASSESSMENTFebruary 1, 2016EngineeringResearch Development and Special Studies
Southwest Power Pool, Inc.Revision HistoryRevision History2DateAuthorChange Description11/4/2015J. McDiarmidInitial Draft2/01/2016D. BowmanReport Complete
Southwest Power Pool, Inc.Table of ContentsTable of ContentsREVISION HISTORY . 2TABLE OF CONTENTS . 3LIST OF TABLES. 4INTRODUCTION . 5STUDY SCOPE AND METHOD . 62.1: Fast Fault Screening and Dynamic Assessment . 82.2: Dynamic Assessment of Member Specified Events . 82.3: Dynamic Assessment of Coordinated Events with Tier 1 Entities . 92.4: Dynamic Assessment of Breaker to Breaker Contingencies . 92.5: Assessment of Possible Cascading Due to Transient Instability . 92.6: Mitigation of Unstable/Cascading Events. 9RESULTS. 103.1: Fast Fault Screening (FFS) and Dynamic Analysis. 103.2: Transient Stability Analysis of Member Submitted Events . 103.3: Dynamic Assessment of Coordinated Events with Tier 1 Entities . 113.4: Transient Stability Analysis of Breaker-to-Breaker Contingencies . 113.5: Assessment of Possible Cascading Due to Transient Instability . 11CONCLUSION . 12APPENDIX A – DATA . 132015 SPP TPL-001-4 Stability Study3
Southwest Power Pool, Inc.List of TablesList of TablesTable 2.1: Study Models . 6Table 2.2: SPP Assessment Areas . 7Table 3.1: Events by Category . 10Table 3.2: Stability Results for Member-Submitted Events . 1042015 SPP TPL-001-4 Stability Study
Southwest Power Pool, Inc.IntroductionIntroductionThe objective of this study is to report findings from the 2015 Dynamic Stability Compliance Assessmentto support compliance with NERC TPL-001-4 Reliability Standards for future years 2016 and 2025. Thisreport, along with the Near-Term and Long-Term Load Flow Assessments, fulfills requirements ofapplicable TPL Standards. This report summarizes the potential stability violations anticipated by SPPand the applicable Corrective Action Plans (CAPS) developed by SPP Member Entities and SPPEngineering Staff.A separate comprehensive report will be issued detailing the 2015 Transmission Planning ComplianceStatement for each TPL Standard. This report will address how each requirement defined in the TPLStandards is fulfilled by one or more mechanism in the TPL Near-Term or Longer-Term ComplianceAssessments.The following terms are used in this report and are defined as follows:Rotor Angle Stability – refers to the ability of synchronous machines of an interconnected power systemto remain in synchronism after being subjected to a disturbance (also known as transient stability). Itdepends on the ability to maintain/restore equilibrium between electromagnetic torque and mechanicaltorque of each synchronous machine in the system. Instability that may result occurs in the form orincreasing angular swings of some generators leading to their loss of synchronism with other generators.1Oscillation Damping – is an influence within or upon an oscillating system that has the effect of reducing,restricting or preventing its oscillations. In the context of the present study, damping is the decay ofdisturbance induced rotor oscillations and is caused by mechanical energy loss in the generator rotor.Transient Voltage Stability (Short-term voltage stability) – involves dynamics of fast-acting power systemcomponents such as induction motors, electronically controlled loads and HVDC converters. The studyperiod of interest is in the order of several seconds, and analysis requires solutions of appropriate systemdifferential equations; that is similar to the analysis of rotor angle stability. Dynamic modeling of loads isoften essential. In contrast to rotor angle stability, short circuits near loads are important.1Cascading - The uncontrolled successive loss of system elements triggered by an incident at any location.Cascading results in widespread electric service interruption that cannot be restrained from sequentiallyspreading beyond an area predetermined by studies.212IEEE/CIGRE Joint Task Force on Stability Terms and Definitions, Definition and Classification of Power System Stability, IEEE PES Trans. on PowerSystems, Vol. 19, No. 2, May 2004.Glossary of Terms Used in NERC Reliability Standards. [Online], Updated Jan. 25, 2016, of%20Terms/Glossary of Terms.pdf2015 SPP TPL-001-4 Stability Study5
Southwest Power Pool, Inc.Study Scope and MethodStudy Scope and MethodThis section summarizes the scope of work performed by SPP, as Planning Coordinator (PC), for the 2015NERC TPL-001-4 Stability Assessment. The full Scope of Work for the study was approved by theTransmission Planning Task Force (TPLTF) on May 11, 2015.The model set in Table 2.1 below establishes category P0 as the normal System condition in TPL-001-4Table 1, and defines the models that are used for the 2015 TPL Stability analysis.DescriptionBase CasesSensitivity CasesYear 1 peakMDWG 2016SITPNT 2016S5Year 1 off-peakMDWG 2016LITPNT 2016L5Year 10 peakMDWG 2025SN/ATable 2.1: Study ModelsThe generation dispatch in the base case models is derived from a member submitted merit order blockdispatch. The ITPNT Scenario 5 models, which were chosen for the sensitivity cases, have as much of thefirm transmission rights protected as load allows. The wind machines are dispatched considerably higherin the ITPNT Scenario 5 models.TPL-001-4, Requirement 2.4.1, states that dynamic cases take into account the behavior of inductionmotors. SPP and their Member companies performed a sensitivity analysis using a generic PSSE loadmodel in a summer peak case. The results from this sensitivity analysis indicated the need for additionalresearch regarding the use of a dynamic load model and its effects on the bulk electric system. Theresearch will include partnering with Electric Power Research Institute (EPRI), leveraging their researchon the subject matter, and the formation of an SPP Dynamic Load Task Force (DLTF). The SPP DLTFhas been tasked to develop and execute a load survey, a set of dynamic load models for different loadtypes, and a methodology to maintain and update them as the electric utility industry moves forwardwith improvements and new dynamic load models.The SPP areas included in this assessment are shown below in Table 2.2:Area Number520542546523545NA5415406506Entity NameAmerican Electric Power (AEPW)Board of Public Utilities (BPU)City Utilities of Springfield, MO (SPRM)Grand River Dam Authority (GRDA)Independence Power & Light (INDN)ITC Great Plains, LLC (ITCGP)Kansas City Power & Light Company (KCPL)KCPL - Greater Missouri Operations (KCPL-GMO)Lincoln Electric System (LES)2015 SPP TPL-001-4 Stability Study
Southwest Power Pool, Inc.Study Scope and MethodArea Number531640524527645515526534544652536525Entity NameMidwest Energy, Inc (MIDW)Nebraska Public Power District (NPPD)Oklahoma Gas & Electric Company (OKGE)Oklahoma Municipal Power Authority (OMPA)Omaha Public Power District (OPPD)Southwestern Power Administration (SWPA)Southwestern Public Service Company (SPS)Sunflower Electric Power Corporation (SECI)The Empire District Electric Company (EDE)Western Area Power Administration(WAPA)Westar Energy, Inc. (WR)Western Farmers Electric Cooperative (WFEC)Table 2.2: SPP Assessment AreasTwenty (20) second time domain simulations are performed for all events described in later sections ofthis report using Siemens’ PTI’s PSS/E Rev 32 and the PSSPLT plotting package and PowerTech Labs’DSATools TSAT (breaker-to-breaker events). As the simulations occur, the following are monitored andrecorded to determine stability:Rotor angle stability is monitored for generators up to ten (10) buses away from the disturbance (fault)location. It is assumed that the absence of instability up to 10 buses away from the disturbance impliesthat generators located beyond this point will remain stable. Should any event cause instability, the eventwill be re-simulated and monitored to capture all possible unstable generators beyond the ten (10) buses.Those units that exhibit signs of instability are marked for further analysis, and should CAPS be necessary,the member entity is engaged to determine the necessary CAP.Rotor angle oscillation damping is monitored for those generators monitored for rotor angle stability. Thedamping curves are judged against the SPPR5 criteria as described in the SPP Disturbance PerformanceRequirements. Those units that violate the criteria were identified for further analysis and, should CAPSbe necessary, the member entity was engaged to determine the necessary CAP.Transient voltage stability is monitored for BES buses up to ten (10) buses away from the disturbance(fault) location. The voltage responses are judged against the .7 Vtransient 1.2 p.u. criteria, as describedin the SPP Disturbance Performance Requirements. Those units that violate the transient voltage criteriaare marked for further analysis and should CAPS be necessary, the member entity is engaged to determinethe necessary CAP.Potential cascading due to a fault event and subsequent rotor angle instability is determined for NERCcategory P1-P7 and Extreme events. The criteria for an event resulting in potential cascading are the lossof more than 1768 MW of generation based on SPP operating reserve. Those events violating these criteriawere identified as a possible cascading event for further analysis and, should CAPS be necessary, themember entity is engaged to determine the necessary CAP.2015 SPP TPL-001-4 Stability Study7
Southwest Power Pool, Inc.Study Scope and MethodWith respect to system stability, compliance with the new TPL-001-4 Standard is required. Paragraphs2.1 through 2.5 of this document describe the events required for study and the method by which they arestudied.2.1: Fast Fault Screening and Dynamic AssessmentA Fast Fault Screening analysis of the SPP Transmission System was performed on all cases shown inTable 2.1. V&R Energy’s Fast Fault Scan (FFS) tool was used to determine category P1 and P6 eventsabove 100 kV. A list of potential severe fault locations, their ranking, and fault sequences for potentialcategory P1 and P6 contingencies was determined. The screening identified 88 severe fault locations forthe study cases.V&R Energy’s FFS tool screens potential transmission fault locations for grid stability analysis andquickly identifies the most severe fault locations and ranks them in the order of severity. The tool beginsby identifying the most severe fault locations, above 100 kV, which are considered the weaker points inthe network. Faults at each of the identified locations are then ranked according to severity using a RankingIndex (RI) for the loss of lines, transformers, or generators according to TPL-001-4 at each ranked bus.SPP classifies fault severity according to the Ranking Index (RI) and the Critical Clearing Time (CCT).Once the RI is known, the CCT is computed. The CCT is the maximum time during which a disturbancecan be applied without generator units losing transient stability. The RI and CCT are used as metrics todetermine fault locations that merit further examination.Transient stability analysis was performed on ranked contingencies having a critical clearing time of lessthan nine (9) cycles using the ranked bus, CCT and the “outaged branch” identified in the FFS. The FFSidentified the fault bus and associated “outaged branches;” however, the fault sequence was determinedby SPP, as follows: Category P1: Apply a three-phase fault at the ranked bus for a time span of CCT cycles, open the“outaged branch,” and clear the fault. Category P6: Open the first “outaged branch” and allow steady state system adjustments. Apply athree-phase fault at the ranked bus for a time span of CCT cycles, open the second “outagedbranch,” and clear the fault.Prior to executing the analysis, discussions with members of actual clearing times to be used during thesimulations are coordinated.2.2: Dynamic Assessment of Member Specified EventsSPP members provided SPP Staff with 4,582 reliability events for transient stability performance analysis.A transient stability analysis was performed for all member submitting events for all Table 2.1 cases.Some events required a change in generation differing from that amount in the powerflow models basedon the member submitted contingency. In such cases, an offset amount was included within the membermodeling area to balance generation prior to or during the event simulation.82015 SPP TPL-001-4 Stability Study
Southwest Power Pool, Inc.Study Scope and Method2.3: Dynamic Assessment of Coordinated Events with Tier 1 EntitiesContingencies on systems adjacent to SPP may impact the SPP system and vice versa. Coordination withadjacent PCs must, therefore, be accomplished. SPP Staff performed a fast fault screening and providedadjacent entities with twenty-one (21) severe fault locations as indicated by the FFS screening for theirreview and further study. SPP also requested the adjacent systems provide events for the SPP study. SPPreceived a total of 1,459 events for study. A transient stability analysis was performed for all receivedevents for all Table 2.1 cases.2.4: Dynamic Assessment of Breaker to Breaker ContingenciesSPP Staff gathered system breaker-to-breaker data to formulate contingencies that emulate actual fieldresponses to faults. Since faults on line segments between breakers normally cause the line-end terminalbreakers to open all line sections, end-to-end de-energization is required during the simulation. A total of1,565 breaker-to-breaker contingencies were produced. A transient stability analysis was performed forall cases shown in Table 2.1 for the formulated breaker-to-breaker contingencies. Powertech Labs, Inc.’sDSATools TSAT was used for the analysis.2.5: Assessment of Possible Cascading Due to Transient InstabilityCategory P1 through P7 and Extreme contingency events that produced the more severe system impactswere evaluated for cascading. A loss of synchronism as a result of an outaged element is the initiatingmechanism for purposes of this assessment. A cascading analysis was performed on all cases shown inTable 2.1 using V&R Energy’s Fast Fault Scan (FFS) and Potential Cascading Modes (PCM) tools. Thisanalysis determined possible cascading due to transient instability within the SPP System.The FFS tool was first used to determine the most severe category P1 fault locations (fault is placed nearthe bus on each branch to be outaged) within the system. The identified fault locations were ranked inorder of decreasing severity (1 being the most severe) using a ranking index. The bus fault and associatedoutaged branch were then used as the initiating event in the PCM tool to determine possible cascading,meaning a criteria violation (loss of 1,768 MW) had occurred. A criteria violation would merit furtheranalysis.Second, Category P2 through P7 and Extreme events were evaluated for potential cascading, as well. Anyloss of MW due to generator instabilities for these events was evaluated against the 1,768 MW criteria. Acriteria violation would merit further analysis.2.6: Mitigation of Unstable/Cascading EventsSPP Staff worked with SPP Members and adjacent entities to determine Corrective Action Plans (CAPS)for events found to be unstable or that resulted in cascading to ensure the proposed CAPS would, byimplementation, provide system stability.2015 SPP TPL-001-4 Stability Study9
Southwest Power Pool, Inc.ResultsResults3.1: Fast Fault Screening (FFS) and Dynamic AnalysisThe 88 severe fault locations (buses) were ranked according to their Ranking Index (RI) and CriticalClearing Time (CCT) for NERC P1 and P6 contingencies. Those ranked locations with a CCT less than 9cycles were identified for time domain analysis in PSS/E. There was no resulting system instability forFast Fault Screened events.3.2: Transient Stability Analysis of Member Submitted EventsMembers provided a total of 4,582 events for study according to the following categories:CategoryP1P2P3P4P5P6P7ExtremeNumber of Events1,221682697052924431621,008Table 3.1: Events by CategoryTransient stability analysis was performed on the above events using PSS/E’s dynamics package. Therewere four (4) events resulting in transient voltage instability as shown below in Table 3.1. The CorrectiveAction Plans are also shown.EventFAULT OKGE2015-All-1-P5 1HSL4 16S-Pass 2FAULT SPS-2015All-91-P4DEAFSMITH6 2K25FAULT SPS-2015All-346-P2DEAFSMITH6 5H65FAULT SPS-2015All-77-P4WHEELER3 1H13510OwnerModelInstabilityCorrective Action PlanTransient VoltageViolations below0.7 p.u.Install backup distance relaying on
8 2015 SPP TPL-001-4 Stability Study With respect to system stability, compliance with the new TPL-001-4 Standard is required. Paragraphs 2.1 through 2.5 of this document describe the events required for study and the method by which they are studied. 2.1: Fast Fault Screening and Dynamic Assessment
SPP 2015 TPL-001-4 Short Circuit Planning Assessment for Selected UMZ Entities 2 y Date Author Change Description 12/23/2015 SPP staff Initial Draft 12/30/2015 SPP staff Final Draft . Southwest Power Pool, Inc. Table of Contents SPP 2015 TPL-001-4 Short Circuit Planning Assessment For Selected UMZ Entities 3 .
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SPS system plan rolls up to Southwest Power Pool (SPP) regional plan and SPP stakeholder process. 2. . TPL-001-2, update to existing TPL-001 through TPL-004 . 5,880 MW by 2015, 10,000 MW by 2025. SPS has energy sales ratio share of total. .
planning assessments . FERC directed NERC to modify TPL -001-4 to address this concern. The second issue involves adding clarity regarding dynamic assessment of outages of critical long lead time equipment, consistent with the entity’s spare equipment strategy. FERC directed NERC to consider this issue upon its next review of TPL-001-4.
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Southwest Power Pool, Inc. Revision History 2 2015 ITPNT Assessment Revision History Date Author Change Description 12/22/2014 SPP staff Draft 12/29/2014 SPP staff Approved by TWG 1/12/15 SPP staff Removed blank rows in Table 5.3 1/12/2015 SPP staff Added Final Reliability Assessment section 1/13/15 SPP staff Updated Table 5.4 with accurate costs per state
The Adventures of Tom Sawyer Book/CD-Rom Pack by (author) Mark Twain, Jennifer Bassett (Series Editor), (9780194789004) Oxford Bookworms Library, Stage 1 (2008) 1a Tom and his Friends. 1. Who was calling Tom? 2. Where did Aunt Polly look first? 3. Where did she look next? 4. What did Tom try to do? 5. What did he have in his pocket? 6. Tom said, “Quick , _ _ _”. 7. Was Aunt .
