Transmission Operations & Real Time System Security. David Mahlmann Spring 2003

Transcription

1 Transmission Operations & Real Time System Security David Mahlmann Spring

2 Outline Overview of Control Area Operation Basic Control Area Operation Frequency, voltage, reserves, regulation, component loading NYISO Security and Regulation SCD and AGC NYISO Transmission System Constraints Summary 2

3 Overview of Control Area Operation 3

4 Overview of Control Area Operation We are all in this together. like it or not! Every generator action effects system conditions. Laws of physics trump economics, legal contracts, and legislative mandates. 4

5 Overview of Control Area Operation If your unit burps, it will be detectable on the interconnected electric system from Saskatoon, Saskatchewan to Florida City, FL from Lawton Oklahoma to Prince Edward Island 5

6 Overview of Control Area Operation If we don t coordinate the collective security of the interconnected power system, the whole business can collapse like a house of cards. It has happened, and it s not pretty: The Great Northeast Blackout November 9 th

7 Overview of Control Area Operation What is a Control Area? An electric system or systems, bounded by Interconnection metering and telemetry capable of controlling generation to maintain its interchange schedule with other Control Areas and contributing to frequency regulation of the Interconnection. NERC Operating Manual 7

8 Typical Control Area 8

9 9

10 Overview of Control Area Operation Quebec Ontario New York Control Area NE PJM 10

11 Overview of Control Area Operation Key Security Indicators Frequency Controlled by load an generation balance Voltage Generator voltage controls, static shunt devices Interchange flows with neighboring control areas Controlled managing system flows through dispatch (load following) Contingency Reserve availability Controlled managing system flows through dispatch Equipment limits Controlled managing system flows through dispatch System limits (e.g.. system stability, voltage stability) Controlled managing system flows through dispatch 11

12 Overview of Control Area Operation Timeframe Control Area operational security is evaluated and acted upon in two time frames: Forecast - day ahead, hours ahead Real time 12

13 Overview of Control Area Operation In order to maintain system security, each control area must: Monitor all key system parameters to insure real-time compliance. Evaluate the impact of all criteria contingencies to insure that no one event will cause security problem. 13

14 Overview of Control Area Operation Ontario Communications, Data & Monitoring Quebec NYISO PJM ISONE Transmission Owners Basepoints Reserve Pickup flag MW Mvar KV HZ Bkrkr status 14

15 Overview of Control Area Operation Contingency Evaluation Standard Contingencies are evaluated to insure security Loss of any single generator Loss of any single line Loss of multiple circuit tower Loss of a single element with a single breaker failure 15

16 Basic Control Area Operation 16

17 CONTROL AREA OPERATION MEANS: BALANCING GENERATION WITH LOAD WHILE RESPECTING TRANSMISSION LIMITATIONS 7 17

18 Key Security Indicators Frequency Voltage Interchange flows with neighboring control areas Contingency Reserve availability Equipment limits System limits 18

19 Contingency Frequency Control Nominally the US electric system is operated at 60 Hz. Normally maintained Imbalance in load an generation will cause frequency to rise or decline Large unit trips L/ MW causes a.03hz decline in the Eastern Interconnection In-service governors required to arrest frequency declines due to load and generation imbalance 19

20 Frequency Control Governors Governor Action Automatic Mechanical interaction set to maintain 60 Hz at a specific RPM. There is a specific dead band where the governor will not respond to frequency. This is typically.036 Hz. 20

21 Generator Interaction Governors Assure governor in service No specific NYISO related operational requirements 21

22 Key Security Indicators Frequency Voltage Interchange flows with neighboring control areas Contingency Reserve availability Equipment limits System limits 22

23 Voltage Control Two categories of voltage control equipment Automatic Matches the reactive demands of the load Provides instantaneous response to contingency conditions Manual Equipment under supervisory control by the transmission system operators Operation coordinated with automatic controls to optimize, to the extent possible, system security. 23

24 Voltage Control Automatic Voltage Regulators (AVRs) Regulates generator excitation to export or import VARs (lag-lead) in order to maintain terminal voltage at a specific setpoint. Static VAR Compensators (SVCs) Static Var Compensators(SVCs) and STATCOM devices perform a special function of high speed voltage response. Both types of automatic voltage control provide smooth control over a continuous range 24

25 Voltage Control Load Tap Changing Transformers (LTCs) Supervisory controlled LTCs allow system operators to change tap ratios. Shunt Capacitor and Reactors Placed in or out of service by system operations via supervisory controls when circumstances require additional resources. Unlike AVRs and SVCs, these device provide step changes in the VAR support. 25

26 Generator Interaction Voltage Control Respond to NYISO requests for reactive support relayed by TO Report AVR outages to the NYISO Respond to TO requests for reactive support. 26

27 Key Security Indicators Frequency Voltage Interchange flows with neighboring control areas Contingency Reserve availability Equipment limits System limits 27

28 Load Following Hourly Basis scheduled in advance of real time by SCUC and BME Off dispatch units are scheduled by the hour Transactions are scheduled by the hour Five Min. Basis Security Constrained Dispatch (SCD) On-dispatch units Six second - Automatic Generation Control (AGC) On Control 28

29 Load Following - SCD SCD dispatches generators with basepoints to meet the 5 minute projected load Primary control of generation based on availability, cost, operating limits, and response rates Calculates calculates reserves an solves constraints. Calculates real time prices 29

30 AREA CONTROL ERROR (ACE) The measurement tool used to identify the imbalance between generation & load (interchange) while contributing to interconnection frequency correction. It also discriminates between internal & external control area faults and accounts for governor response during frequency excursions when operating in Tie-Line Bias mode. 30

31 Load Following - AGC Compensates for overgeneration or undergeneration; supplementary control for adjustments in interchange and frequency. Calculates six second basepoints for all units Passes through SCD basepoints for units not on control at six second intervals. Tracks generation output with response to AGC for monitoring compliance with the NERC reliability standards CPS1, CPS2, and DCS 31

32 Auxiliary application AGC Time Correction Manual Intervention within centralized AGC When the time exceed in the Eastern Interconnection exceeds the bounds of +- 8 seconds Correct for time error with frequency offsets or in all the Control Areas 32

33 Generator Interaction with Load Following Day ahead commitment and schedule from SCUC. Hour ahead commitment and schedule from BME AGC control signals six second SCD dispatch signals five minutes Instruction through the TO system operator 33

34 Key Security Indicators Frequency Voltage Interchange flows with neighboring control areas Contingency Reserve Equipment limits System limits 34

35 Reserve Requirements Operating Reserve A real time quantity 1.5 times the largest contingency Separate and distinct from installed reserve or Installed Capacity (ICAP). Installed capacity is acquired to assure that when the time comes there will be resources available to provide operating reserve. 35

36 Reserve Requirements Largest Contingency The New York requirement for reserve can vary in real time operation. Typically the reserve requirement is 1800 MW based on the based on a 1200 MW import from HQ or 9 Mile Point 2 Based on the loss of energy from the largest single contingency HQ imports all come in on one line, loss of that line, creates an energy shortage in NY similar to a unit trip 36

37 SINGLE LARGEST CONTINGENCY 1,200 MW 10 MIN SYNC 600 MW min + 30 MIN 600 MW 10 MINUTE TOTAL 1,200 MW 10 MIN NON-SYNC What is needed in addition to 10 min SYNC (600) to total 1200 MW RESERVE REQUIREMENT: 1,800MW 37

38 Generator Interaction with Reserve Requirements NYISO instituted TO communicated Reserve Pick-up Payment based on following NYISO basepoints Economic selection, not necessarily units carrying reserve Performance penalties suspended Max Gen Pick-up Generation expected to produce at maximum capability reimbursed for energy produced Performance penalties suspended. Selective Max Gen Pick-up Instituted on a company basis 38

39 Generator Interaction TO instituted Reserve Activation Reserve The TO can activate any reserve in his area. The TO notifies the NYISO of the reserve activation Max Gen Pick-up Generation expected to produce at maximum capability reimbursed for energy produced Performance penalties suspended. 39

40 Key Security Indicators Frequency Voltage Interchange flows with neighboring control areas Contingency Reserve availability Equipment limits System limits 40

41 Equipment limits Thermal heating Limits Ramp rates Voltage limits - high and low 41

42 Generator Interaction Equipment Limits Primarily rolled into operating limits as part of the bid process. Real time changes to equipment limits must be passed on to the NYISO via the TO. Tube leaks Loss of feed pumps Emission limits Fuel problems 42

43 Key Security Indicators Frequency Voltage Interchange flows with neighboring control areas Contingency Reserve availability Equipment limits System limits 43

44 System Limits Thermal Stability Limits Voltage Collapse limits Locational Reserve limits Local Reliability constraints 44

45 Generator Interaction System Limits There is rarely an area where the generator would have interaction. This is an area of coordination between Control Areas and Transmission Owners. 45

46 NYISO Security and Regulation 46

47 ISO Security & Regulation SCD 8Normal Normal Operation 8 SCD 5 minute dispatch-or Operator initiated 8 SCD re-dispatch system from last dispatch 8 Calculates load 8 EMS Monitors All: 8Device outages 8Line flows & losses 8Generation output 8System interfaces 8Constraints 8Reserves & regulation margin 8Energy schedules 8Calculates inadvertent w/ external control areas 47

48 ISO Security & Regulation BILATERAL BIDS GENERATION BIDS LOAD BIDS LOAD FORECAST ZONE GENERATOR LIMITS MIS CURRENT MARKET INFO SYSTEM DATA BASE Unaccepted & Unexpired POST S D.A TOMORROW GEN SKEDS BILATERALS POSTS H.A. NEXT HOUR GEN SKEDS BILATERALS SORTER BY: SCHEDULE DATE/TIME CATEGORY SCD INPUTS S C U C B M E S R E OUTAGE OUTAGE SCHEDULER SCHEDULER REAL TIME PHASE SHIFTER FLOWS IS+ SECURITY CONSTRAINTS REAL TIME SYSTEM DATA TO s DATA LINK S C D A G C P T S

49 ISO Security & Regulation SCD 8 Reserve Pick-up Operation 8 SCD 10 minute dispatch 8 SCD re-dispatch system from last real time output 8 Calculates load 8 EMS Monitors All: 8Device outages 8Line flows & losses 8Generation output 8System interfaces 8Constraints 8Reserves & regulation margin 8Energy schedules 8Calculates inadvertent w/ external control areas 49

50 NYISO Transmission System Constraints 50

51 NYISO Transmission System Constraints System Limits Stability Limits Invoked on a interface basis Central East Voltage Collapse limits Applicable only to Central East Locational Reserve limits Local Reliability constraints 51

52 NYISO Transmission System Constraints New York State Transmission System 2,500 MW Moses- St. Lawrence Dennison Moses South Colton Saunders Massena Chateauguay Willis Plattsburgh Sandbar 4,400 MW Legend: 765 kv 500 kv 345 kv 230 kv 115 kv Dysinger East Oswego Complex Somerset West - Central Beck Niagara Sta.80 Pannell Homer City Adirondack Marcy Central - East Hoosick Coopers Corners Rock Tavern Roseton Rotterdam Buchanan Ramapo W49St/Rainey Whitehall Blissville New Scotland Farragut Goethals Pleasant Valley Millwood Sprain Brook - Dunwoodie Sprainbrook Dunwoodie Bennington Robinson Rd. Clay Edic Porter Huntley Lafayette Gilboa Alps Stolle Rd. Richfield Inghams Leeds Gardenville Meyer Springs Dunkirk Andover Palmiter 4,700 MW Total - East 5,500 MW Fraser Watercure Hillside Oakdale 8,000 MW Upny - Con Ed Shore Rd. E.Garden City 5,000MW Con Ed-LIPA

53 Dysinger East NEW YORK INTERNAL INTERFACES West - Central Central - East NS1 & SR2 Stolle - Meyer 67 Andover - Palmiter 932 Lockport - Telegraph Rd N. Akron N. Akron Oakfield Sweden Sweden 113 Moses South Pannel - Clay 1 & 2 Stolle - Meyer 67 Mortimer - Elbridge 1 & 2 Quaker - Sleight Rd. 13 Pannel - Farmington So. Perry - RGE 906 Clyde - NYSEG Farmington - NMPC Quaker - Macedon 930 Andover - Palmiter 932 Total East Plattsburgh - Vermont PV20 Edic - New Scotland 14 Marcy - New Scottland 18 Porter - Rotterdam 30 & 31 Richfield Springs - Inghams 942 Inghams PAR Inghams R81 (OCB) UPNY - Con Ed Massena - Marcy MSU1 Dennison - Sand Stone 5 Dennison - Colton 4 Alcoa - Browning Moses - Adirondak 1 & 2 Sprain Brook - Dunwoodie South Dunwoodie - Rainy 71 & 72 Dunwoodie - Sherman Creek 31 Dunwoodie So. - E 179th St Sprian Brook - Tremont X28 Sprain Brook - W 49th M51 & M 52 Jamaica - Valley Stream 901 Jamaica - Lake Success 903 Plattsburgh - Vermont PV20 Edic - New Scottland 14 Marcy - New Scottland 18 Porter - Rotterdam 30 & 31 Richfield Springs - Inghams 942 Inghams PAR Inghams R81 (OCB) Fraser - Gilboa GF5-35 West Woodbourne (T1-52) Ramapo - So. Mahwah 69 & 70 Ramapo - Branchburg 5018 Coopers Corners - Rock Tavern 34 & 42 Linden - Gothals A 2253 Hudson - Farragut B 3402 & C 3403 Ramapo - Buchanan 94 Ladentown - Buchanan 88 Roseton - East Fishkill 305 Pleasant Valley - East Fishkill F36 & F37 Pleasant Valley - Wood St. F30 Pleasant Valley - Millwood F31 Fishkill - Sylvan Lake 990 East Fishkill Bank Con Ed LIPA SprianBrook - E. Garden City Y49 Dunwoodie - Shore Rd Y50 Jamaca - Lake Success 901 Jamaca - Valley Stream 903 Northport - Norwalk Harbor

54 STABILITY LIMIT: = Penalties Saunders Chateauguay New York State Transmission System Moses- St. Lawrence Dennison Colton Massena Willis Plattsburgh Sandbar Legend: 765 kv 500 kv 345 kv 230 kv 115 kv Somerset Beck Niagara Sta.80 Huntley Stolle Rd. Gardenville Dunkirk Robinson Rd. Homer City Pannell Meyer Andover Palmiter Watercure Hillside Oswego Complex Oakdale Adirondack Marcy Clay Edic Lafayette Richfield Springs PENALTIES ON CENTRAL - EAST Central - East Hoosick Porter Inghams Fraser Coopers Corners Rock Tavern Gilboa Roseton Rotterdam Buchanan Ramapo W49St/Rainey Whitehall Blissville New Scotland Total - East Farragut Goethals Alps Leeds Pleasant Valley Millwood Sprainbrook Dunwoodie Bennington Shore Rd. E.Garden City

55 Summary The foundation for maintaining system security reliability comes from the the adequacy and and security of: Frequency, Voltage, Reserve, Regulation, while respecting equipment and interface limits. The NYISO uses SCD and AGC to dispatch generation, balance load and respect operating limits. Interface constraints vary depending on system conditions. The Central East interface is usually most restrictive. 55