NERC Load Modeling Activities. Ryan D. Quint, PhD, PE Senior Engineer, System Analysis, NERC MRO Fall Reliability Conference November 2016

Transcription

1 NERC Load Modeling Activities Ryan D. Quint, PhD, PE Senior Engineer, System Analysis, NERC MRO Fall Reliability Conference November 2016

2 Introduction Kickoff January 2016 LMTF webpage Chair: Dmitry Kosterev, BPA Focus Areas 2 Coordination with Regional load modeling groups Broad expertise involvement Full utility industry coverage and participation Consolidate and share load modeling practices across industry Tasks Support industry wide advancement of dynamic load modeling Develop guidelines, technical references, industry webinars, etc. Help ensure robust software implementation Share lessons learned and study approaches

3 History & Background Why is this important? How did we get to where we are today? 3

4 Why Dynamic Load Modeling? Validation of power voltage oscillations WECC: July 2 and August , August Fault Induced Delayed Voltage Recovery (FIDVR) Observed as early as 1980s in Southern California, Florida, Georgia, mid West Related to stalling of residential airconditioners Distributed energy resources Emerging need in early 2010s

5 Air Conditioner Testing Round 1 SCE, EPRI, and BPA tested singlephase residential A/C units Voltage sags, ramps, oscillations, frequency excursions Stall for sudden ΔV to 50 60% of nominal in less than 3 cycles Once stalled, they remain stalled Cannot overcome load torque coolant pressure must equalize Reactive power up to ~ 7x rated Thermal protection trips in 2 30 seconds 5

6 Air Conditioner Testing Round Power (kw) Stall Voltage (per unit) Ambient Temperature (F) 6

7 Development of Initial Performance Model Compressor Real Power [W] F 110F 105F 100F 95F 90F 85F 80F STALL Real Power STALL RUN Motor stalls when voltage drops below V stall for duration T stall V stall ~ pu 6 T stall ~ sec Real Power Compressor Reactive Power [VAR] Reactive Voltage Power [V] F 110F F STALL 100F 95F F 85F 80F STALL Real Power (per unit) STALL STALL RUN 2000 RUN Voltage [V] Voltage (per unit) Source: BPA

8 Electromagnetic Transient Simulations 5 kw 1 ph A/C H = sec Speed is pulled down very strongly by negative T elec Negative peak of electrical torque ~8x rated torque Current by stalled motor 5x rated current 8 Source: J. Undrill

9 Electromagnetic Transient Simulations 100 kva 3 ph Motor H = 0.3 sec Speed minimally pulled down by negative T elec Negative peak of electrical torque ~1 2x rated torque Current returns to near rated current 9 Source: J. Undrill

10 Point-on Wave Simulations Common mode failure of testing Applied voltage sag at point on wave zero crossing in every test Instantaneous voltage drop to 0.62 pu for 3 cycles Voltage zero crossing Voltage peak Voltage 45 deg point Worst case zero crossing 10 Source: Univ. Wisconsin

11 Stall Voltage vs. Point on Wave Simulation Source: Univ. Wisconsin 11

12 Stall Voltage vs. Point on Wave Testing Source: Univ. Wisconsin, BPA 12

13 Scroll vs. Reciprocating Scroll Compressors Vast majority of new compressors Better fault ride through ability May run backwards after fault ~1 1.25x rated current not locked rotor up to tens of minutes Estimated to be ~ 50% of A/C fleet today (2015 NERC FIDVR Workshop) Reciprocating Compressors Majority of fleet until 2000s Disappearing due to energy efficiency requirements Source: BPA 13

14 Meeting the Needs of TODAY for Dynamic Load Modeling Addressing issues and practices with the existing dynamic load models 14

15 Technical Reference Document Documents current state of dynamic load modeling Follow up to the NERC FIDVR Workshop in September 2015 Final NERC PC approval and publication in December

16 Network Boundary Equations & Initialization Standardized procedures for software initialization Familiarize and standardize practices for dealing with current sources in dynamics motor model numerical issues Overcome crashing issues 16 Source: PowerWorld

17 Common Initialization & Network Boundary Equations Source: PowerWorld 17

18 Load Model Benchmarking Initial LMTF member and vendor benchmarking NERC LMTF default data set tested using standard test events Results being compiled to identify any discrepancies Fixing any software implementation issues identified Voltage Flow (Measured at From End) Bus V mag [pu] From Bus To Bus Flow MW Flow MVar

19 Load Model Benchmarking P-M MOTOR A P (PU ON SYSTEM MVA BAS PTI GE Source: PacifiCorp 166 P load [MW] 165 PSLF PSSE PowerWorld TSAT P load [MW] Source: PowerWorld Time [s] 19

20 Robust Default Data Sets Developed robust default data sets for use across regions as starting point Suitable and reasonable parameters for tripping Can be modified with regional data, composition data 20

21 Reliability Guideline: Load Composition Guideline on developing representative load composition data for dynamic load models 21 Source: WECC

22 Reliability Guideline: Load Composition Guideline on developing representative load composition data for dynamic load models 22

23 Reliability Guideline: DER in Dynamic Load Models Guidance on modeling DER in dynamic load models and powerflow models Coordination with DERTF efforts 23

24 Reliability Guideline: DER in Dynamic Load Models Utility Scale Distributed Energy Resources (U DER): distributed energy resources directly connected to the distribution bus or connected to the distribution bus through a dedicated, non load serving feeder. These resources are specifically three phase interconnections, and can range in capacity, for example, from 0.5 to 20 MW although facility ratings can differ. Retail Scale Distributed Energy Resources (R DER): distributed energy resources that offset customer load. These DER include residential, commercial, and industrial customers. Typically, the residential units are single phase while the commercial and industrial units can be single or three phase facilities. 24

25 Reliability Guideline: DER in Dynamic Load Models 25

26 Reliability Guideline: DER in Dynamic Load Models Source: PowerWorld 26

27 Industry-Wide Webinar Broader industry engagement Topics to cover Fundamentals of end use load Composite load model Parameters and their meaning Load composition data Distributed energy resource modeling Sensitivity analysis December 9 announcement to be made shortly 27

28 Utility Forum: Dynamic Load Modeling 28

29 Meeting the Needs of TOMORROW for Dynamic Load Modeling Addressing issues and practices with future dynamic load models 29

30 Progressive Stalling and Tripping Source: J. Undrill Source: PowerWorld 30

31 Efficient Data Format & Model Management Modularized load model structure Plug n play concept Distinction between network and load components Explicit DER representation Data input groups 31

32 Dynamic Load Modeling in Real-Time Stability Analysis Why do we ignore real time modeling practices? Why do we require induction motor load in planning studies but not in real time studies? What are the limitations in moving towards inclusion of induction motor load in realtime models? How do we proceed cautiously? 32

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