ERSWG Measure 6 - Ramping. Troy Blalock NERC RS Chairman September 14, 2016

Transcription

1 ERSWG Measure 6 - Ramping Troy Blalock NERC RS Chairman September 14, 2016

2 EASTERN INTERCONNECTION HOURLY CPS1 EXCEEDANCE COUNTS 2

3 Hourly CPS1 Exceedance Counts Group by BA 3

4 Hourly CPS1 Exceedance Counts Group by BA, Year and Month of Year

5 WESTERN INTERCONNECTION Hourly CPS1 Exceedance Counts 5

6 Hourly CPS1 Exceedance Counts Group by BA 6 * CPS1 not shown for BA with Variable Bias

7 Hourly CPS1 Exceedance Counts Group by BA, Year and Month of Year * CPS1 not shown for BA with Variable Bias

8 BA X individual CPS 1 Performance 8

9 Troy Blalock, P.E. South Carolina Electric & Gas Company 601 Old Taylor Rd. Cayce, SC Mail Code J42, Cayce, SC Office #: Cell #: Fax #:

10 ERSWG NERC RS Report Measure 1 Synchronous Interconnection Inertia Measure 2 Initial Frequency Deviations Following Largest Contingency Measure 4 Frequency Response at Interconnection Level Measure 6 Net Demand Ramping Variability Troy Blalock NERC RS Chairman September 14, 2016

11 Measure 1: Interconnection Inertia EASTERN INTERCONNECTION 2

12 Eastern Interconnection System Inertia Timestamp Total Interconnect inertia contribution, MVA*s Interconnect Load, MW Interconnects inertia constant H, using system load as a base, s Rate of Change of Frequency at RCC, Hz/s Frequency deviation with first 0.5 seconds Time to UFLS(59.7 Hz) (without any other responses) 4/20/2016 8: /20/2016 9: /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /20/ : /21/2016 0: /21/2016 1: /21/2016 2: /21/2016 3: /21/2016 4: /21/2016 5: /21/2016 6: /21/2016 7: /21/2016 8: /21/2016 9: /21/ : /21/ :

13 Eastern Interconnection System Inertia Total Interconnect inertia conribution, MVA*s Interconnect Load, MW /16/2016 0:00 4/20/2016 0:00 4/24/2016 0:00 4/28/2016 0:00 5/2/2016 0:00 5/6/2016 0:00 5/10/2016 0:00 4

14 Summary Stats May and June

15 MEASURE 1: INTERCONNECTION INERTIA Western Interconnection 6

16 7

17 MEASURE 1: INTERCONNECTION INERTIA ERCOT Interconnection 8

18 PUBLIC 9

19 PUBLIC 10

20 MEASURE 1: INTERCONNECTION INERTIA Quebec Interconnection 11

21 12

22 13

23 Measure 2 Initial Frequency Measure 2 Initial Frequency Deviations Following Largest Contingency RATE OF CHANGE OF FREQUENCY (ROCOF) UPDATE 14

24 Measure 4 Frequency Response at Interconnection Level FREQUENCY WORKING GROUP (FWG) CHAIR NGUYEN REPORTED THAT THE FWG MET ON JULY 27, THE FWG SELECTED M4 AND BAL FREQUENCY EVENTS FOR APRIL, MAY, AND JUNE 2016 FOR THE EASTERN, ERCOT AND QUEBEC INTERCONNECTIONS AND FOR MARCH, APRIL, AND MAY 2016 FOR THE WESTERN INTERCONNECTION. 15

25 Measure 6 Net Demand Ramping Variability 16

26 EASTERN INTERCONNECTION HOURLY CPS1 EXCEEDANCE COUNTS 17

27 Hourly CPS1 Exceedance Counts Group by BA 18

28 Hourly CPS1 Exceedance Counts Group by BA, Year and Month of Year

29 WESTERN INTERCONNECTION Hourly CPS1 Exceedance Counts 20

30 Hourly CPS1 Exceedance Counts Group by BA 21 * CPS1 not shown for BA with Variable Bias

31 Hourly CPS1 Exceedance Counts Group by BA, Year and Month of Year * CPS1 not shown for BA with Variable Bias

32 BA X individual CPS 1 Performance 23

33 Troy Blalock, P.E. South Carolina Electric & Gas Company 601 Old Taylor Rd. Cayce, SC Mail Code J42, Cayce, SC Office #: Cell #: Fax #:

34 UTK Rate of Change of Frequency (ROCOF) Update NERC Resources Subcommittee July 2016 Terry Bilke Ling(Ellen) Wu Yilu Liu

35 Agenda Background Recent progress and observations Possible applications of ROCOF Next steps and recommendations Desired locations

36 Background UTK Frequency Network (FNet) samples voltage, angle, and frequency 10x/second Provides real-time visualization and notification of events GPS time-stamped data stream can be used to measure ROCOF, oscillations, angle change etc. Situational awareness that something of significance has occurred on the Interconnection Benchmarking of ERS and other grid parameters

37 Recent Progress Performed pilot ROCOF benchmarking by Interconnection Looked at factors that caused high and low ROCOF Tested ROCOF as an input in estimating resource loss Tested Interconnections for trends in ROCOF

38 ROCOF Regression by Interconnection ROC-T3, mhz/s QUEBEC ERCOT WECC EI Actual Loss/MW Analyzed events: EI: 423 events from Dec to Feb WECC: 157 events from Jan to Feb ERCOT: 179 events from Dec to Feb QUEBEC: 102 events Mar to Dec Recommend tracking regression annually Decreased inertia would lead to a counterclockwise rotation over time

39 Regression Line Slope vs. System Capacity QUEBEC ERCOT WECC EI The slope values of the regression lines in the pervious page is indicated as the dots. X axis is the capacity size of the system in GW. Y axis is the slope of the regression line. The relationship is : yy = aa xx bb a=4656 b= R-square of the fitting :

40 Low Eastern Interconnection ROCOF Outliers Likely reasons for low ROCOF Slow generator trip Runback Data error High inertia Event time: 2015/11/12 16:32:32 UTC On Peak Amount: 1280MW in PA Frequency(Hz) :17 32:24 32:31 32:38 32:45 32:53 33:00 33:07 33:14 33:21 33:29 Time(s) Event time: 2016/01/09 08:37:01UTC Off Peak, likely runback Amount: 977MW in LA Frequency(Hz) :46 36:53 37:00 37:07 37:14 37:21 37:27 37:34 37:41 37:48 37:55 Time(s)

41 EI High ROCOF Outliers Event :53:29 ROC_A3 : Amount: 1194MW Ox2A5CC30C Event :08:05 ROC_A3: Amount: 1138MW 790D9B Event :47:04 ROC_A3: Amount: 1231 MW 14 Outliers generally off-peak and during shoulder months Event :17:32 ROC_A3: 8.7 Amount: 710MW B

42 High EI ROCOF Outliers (Case 1) Frequency(Hz) Event time: 2016/03/02 07:53:29 UTC (off-peak) Amount: 1194MW in Northeast :14 53:21 53:27 53:34 53:41 53:47 53:54 54:01 54:08 54:14 54:21 Time(s)

43 High EI ROCOF Outliers (Case 2) Frequency(Hz) Event time: 2016/01/25 06:47:04 UTC (off peak) Amount: 1231 MW in Northeast :41 58:47 58:54 59:01 59:08 59:15 59:21 59:28 59:35 59:42 59:49 Time(s)

44 High EI ROCOF Outliers (Case 3) Frequency(Hz) Event time: 2015/11/21 17:08:05 UTC (on peak Saturday) Amount: 1138 MW in Midwest :50 07:56 08:03 08:09 08:16 08:23 08:29 08:36 08:43 08:49 08:56 Time(s)

45 High EI ROCOF Outliers (Case 4) Frequency(Hz) Event time: 2015/11/29 17:17:32 UTC (daytime Sunday) Amount: 710MW in Midwest :17 17:24 17:31 17:38 17:45 17:52 17:59 18:06 18:13 18:20 18:27 Time(s)

46 Other Interconnection Outlier Observations ERCOT Six high ROCOF outliers All off-peak hours Quebec Two outliers, one off peak WECC One outlier, (6:06AM PDT)

47 High ROCOF (Possible Low Inertia) Factors High rate of change for given resource loss size Predominantly off-peak hours Trace accompanied by oscillations, possibly coincident transmission events Two of the outliers were DC tie trips May be value in position plotting high ROCOF events Edges of the Interconnection more predominant? Weak network?

48 ROCOF Trends East ERCOT ROCOF may be decreasing in ERCOT and increasing in HQ WECC HQ

49 ROCOF Applications A performance indicator directly related to inertia (which side and distance from the Interconnection regression line) Benchmark Interconnection performance over time Back calculator to flag outliers shortly after event High ROCOF outliers could also point to bad data Position plots of high ROCOF outliers over time might point to weak or weakening network Improve the algorithm to estimate the size of a resource loss The current approach uses the A to B change ROCOF could be included as a factor in the regression on event size

50 Next Steps Test Trend regression Test ROCOF as input to loss estimation Select time to point C for to select common time interval for ROCOF calculation Suggest 95 th percentile of fastest Interconnection Use common time window for all Interconnections Provides some protection against changing measurement approach should inertia decline Explore other ERS support and situational awareness capabilities Fill gaps in FDR placement

51 Desired FDR Locations There still are gaps that should be filled to improve the quality and robustness of the FNet network UTK can provide FDRs for free for those willing to install them at desired locations See listing at

52 For 9-16 call Either an abstract or an executive summary section This guideline provides strategies and recommended practices for reactive power operations, planning and voltage control. Voltage must be controlled to protect system reliability and move power where it is needed in both normal operations and following a disturbance. This guideline provides strategies and recommended practices for reactive power operations, planning and voltage control. Voltage is supported through supply of reactive power; hence, reactive power is required to transfer large amounts of real power across the grid to serve the loads. Reactive power must be supplied locally, mainly because of its dependence on voltage difference. It is usually necessary to site reactive devices very near or at the location that is deficient. Reactive power planning and reactive needs in the operating horizon vary significantly between Transmission Operators across the NERC footprint. In the operating horizon, sufficient reactive resources need to be available to ensure that voltage levels and, reactive flows, and reactive resources are monitored, controlled, and maintained within limits in Real-time or near Real-time to protect equipment and the reliable operation of the Interconnection. In the planning horizon, sufficient reactive resources need to be planned for, such that the transmission system can meet planning performance requirements under a wide range of probable contingencies and result in a system that can be operated reliably over a broad spectrum of system conditions ranging from the peak period of a heavy load day through an extremely light load period, such as the early morning hours during a spring or fall holiday weekend, and following a wide range of probable contingencies throughout the continuum of operating conditions. In addition to a myriad of changing conditions there is an inherent difference in the reactive behavior between a typical large urban area and that of a typical large rural area in such variables as load level and load power factor, various overhead and underground transmission network configurations, dynamic and static reactive resources and, the appropriate minimum and maximum voltage limits. In some areas steady state voltage control and/or transient voltage response are of greater concern than in other areas. Due to these inherent differences the reactive performance of a system is often computed based on a more granular sub-system basis. While reactive power planning and operational needs vary significantly across North America and Canada based on local system characteristics and practices, the NERC Reliability Standards define a set of requirements to ensure reliable planning and operation of the bulk power system. The primary standards codifying reactive power requirements in the operations and planning timeframes include VAR-001-4, VAR-002-4, TPL-001-4, and TOP

53 This guideline provides detailed background discussion regarding the reactive characteristics of system components, system reactive behavior and analytical techniques. This guideline also provides recommended practices for reactive power operations, planning and voltage control. The appendices included in the guideline provide the reactive planning practices, procedures, and requirements for an array of entities across North America. The entities have provided this information as typical of their practices and philosophies at the time that this guideline was developed. These practices are expected to change and evolve overtime.

54 1 Towards zero synchronous generation: GE Renewables philosophy and field experience Nicholas W. Miller w/ Sebastian Achilles, Wei Ren, Carl Wegner, Bob Delmerico July 18 th, 2016 IEEE PES GM Boston, MA

55 Outline Some History of Zero Inertia/All inverter Systems Today s reality Some challenges looking forward

56 Metlakatla BESS c

57 4 A difficult environment Load Power Load VARs Reference: Battery Energy Storage System for Metlakatla Power & Light, N.W. Miller, et.al. 5 th Int l Conference on Batteries for Utility energy Storage, Puerto Rico, 1995

58 5 Twenty years ago Reference: Design and Commissioning of a 5 MVA, 2.5MWH Battery Energy Storage System, N.W. Miller, et.al. IEEE SPM 1996

59 6 Virtual Synchronous Machine - VSC Since the BESS may be required to support and isolated electrical load, the PCS is designed with selfcommutating.. (PWM) to generate a controllable AC voltage waveform.. the generated voltage is completely controllable Reference: Design and Commission of a 5 MVA, 2.5MWH Battery Energy Storage System, N.W. Miller, et.al. IEEE SPM 1996

60 7 Some details Reference: Design and Commission of a 5 MVA, 2.5MWH Battery Energy Storage System, N.W. Miller, et.al. IEEE SPM 1996

61 8 Trip to zero Voltage inertia island Power DC Current 1 second/major division Frequency Reference: Design and Commission of a 5 MVA, 2.5MWH Battery Energy Storage System, N.W. Miller, et.al. IEEE SPM 1996

62 9 Resync zero inertia island to grid Power AC Current Frequency 1 second/major division Reference: Design and Commission of a 5 MVA, 2.5MWH Battery Energy Storage System, N.W. Miller, et.al. IEEE SPM 1996

63 10 Where are we now? Majority of wind and PV use current controlledvoltage source inverters In general, these converters need a minimum short circuit strength to operate Present practice aims to: Be aware and planning for low/minimum levels of composite short circuit ratio Improve behavior of inverters at low cscr recent improvements are substantial these aren t your grandmother s PLLs anymore!

64 How strong are grid conditions? There are few different indicators proposed in the industry: GE Composite SCR (CSCR) considers the grid strength as seen by all electrically close converters and is used for wind plants. This panel considers approaching zero! ~ Converter locations ~ ~ WP1 WP 2 WP 3

65 12 Crazy Weak Grid: cscr << 1 Selective trip of WTGs.very fast Active Power Reactive Power From: Stable Operation of Low Shortcircuit Grids with Advanced Control of Double-Fed WTGs, Sebastian Achilles Post-line Trip cscr << 1.0 Nicholas W. Miller Impossible to evacuate rated power July 29 th, 2015, IEEE PES GM, Denver, CO Fast-stop a portion of wind plant to raise cscr ~ 1.+ Voltage controls tuned to weak grid (retained units stay stable)

66 13 Virtues and Challenges The present current-controlled VSI arrangement has many virtues: In Regulates voltage, and if instructed, provides frequency response Coordinates well across multiple independent converters; shares current well Uses current carrying capability of valves well; is highly cost effective Well suited to (e.g. UL1741 ) required active antiislanding control

67 14 Looking forward Problem is clearly solvable, but not just a question of wind/solar converter design. Industry needs to decide if/when islands are allowed, especially with distributed resources What is the value of: Zero, near-zero SCR and/or inertia operation? Black-start? How is protection to be handled in a world with all inverter based generation (and loads)? nicholas.miller@ge.com

68 Inertia and Frequency Response NERC ERSWG Meeting September 2016

69 Frequency Control Objectives 1. Secondary Frequency Control: Stable and coordinated operation under normal conditions 2. Primary Frequency Control: Arresting and recovery of frequency during contingencies Avoid UFLS operation and large-scale outage 2

70 Steam-Turbine Response Timeframes Power [MW] Frequency [Hz] Power [MW] Frequency [Hz] Time [sec] Example of steam-turbine generator in turbine control mode Time [sec] Source: BPA Example of steam-turbine generator in load control mode Power [MW] Frequency [Hz] Example of steam-turbine generator baseloaded Time [sec]

71 Hydro Unit Response Timeframes 340 John Day Powerhouse # McNary Powerhouse # Power (MW) Frequency (Hz) Power (MW) 155 Frequency (Hz) Time (sec) Example of slow hydro unit response Time (sec) Source: BPA Example of fast hydro unit response 4

72 Combined Cycle Response Timeframes Source: BPA Example of combined cycle plant with gas-turbine units in temperature control mode Example of combined cycle plant with gas-turbine units in load control mode 5

73 Type 3 Wind Response Timeframes 6 Source: GE

74 Type 4 Wind Response Timeframes 7 Source: Siemens

75 Solar PV Response Timeframes Source: First Solar 8

76 Timeframe Takeaways Response times of conventional units based on physical characteristics of source Inverter-based generation relatively fast, more dependent on controls and operating point, slightly dependent on source Paradigms: Current inverter-based resources installed with similar response time as conventional fleet Potential Future speed up response time as appropriate to ensure response during arresting phase 9

77 Wind Inertial Response Siemens Inertial Response Example: Initiates f < 59.7 Hz Terminates f > Hz RampUp ~20% per second RampDown ~10% per second Power boost 10% of available Duration 10 seconds Time delays seconds Controller Plant-level Source: Siemens 10 Source: GE

78 Primary Frequency Response Frequency response timeframes Ensure response in line with system needs Classifications of response fast, slow, inertial really unnecessary otherwise Is inertial response necessary, assuming timely PFR? Inertial Response Fast Frequency Response Conventional Frequency Response Secondary Control Wind Hydro AGC Solar Gas Energy Storage Steam Combined Cycle 11

79 Rate of Change in Simulation 12 Source: LBNL

80 Rate of Change Challenge Inertial, fast, and some slow FR Inertial and fast FR Inertial and some fast FR 13 Source: UTK

81 Rate of Change Variances Source: UTK 14

82 Simulation of Inverter-Based Controls Full Responsiveness Inverter Control w/o Baseload Inverter Control w/ 5% Droop Root Case As-Is No Control 15

83 Key Takeaways from Simulation Inertia and FR are tightly coupled Declining inertia becomes risk when insufficient FR is available Inverter-based resources can respond fast to frequency decline, supporting arresting period Impacts ROCOF raises nadir and moves to left (faster) High ROCOF (initial frequency dip within 200 ms) due to lower inertia different issue than overall FR Arrested frequency not correlated to inertia, correlated to controls capability and responsiveness Same amount of MW replaced by inverter-based = improved FR No control from these resources results in poor FR performance 16

84 Simulation of 100% Inverter- Based Generation Source: PSERC, ASU 17

85 Strategies to Support Declining Inertia Incumbent upon the ERO to proactively help ensure reliable operation of the BPS under a changing resource mix Understand and assess potential future condition Grid codes ensure primary frequency response capability Incumbent upon BAs to provide primary frequency response Sufficient FR reserve available ( headroom based on dispatch) Ensure units performing to specifications 18

86 19