VARIABLE TRANSFERS 2/11/2014. DTC Task Force. Ramu Ramanathan 2/10/2014 1

Transcription

1 VARIABLE TRANSFERS 2/11/2014 DTC Task Force Ramu Ramanathan 2/10/2014 1

2 MW Transfer WHAT IS VARIABLE TRANSFER? VT 1 ST VT 2 Time Static Transfer (ST): Conventional transfers across a path / flowgate, usually made up of fixed hourly schedules between defined PORs (Points of Receipt) and PODs (Points of Delivery) Variable Transfer (VT): Refers to the physical variations in actual power flows across a path / flowgate that are generally unpredictable and repetitive during a defined time period (e.g. 30 minutes). 2/10/2014 2

3 WHY VARIABLE TRANSFER LIMIT IS NEEDED IN NW? No ISO or RTO in the region. No one coordinate and control all the reactive devices in real time in the region to maintain the voltage profile. Voltage and transient stability are not yet studied in real time and proper control actions are not implemented. Many shunt devices and transfer taps are not automatically controlled to maintain proper voltage profile. RAS is manually armed. Lot more Variable Energy Resources are integrated in NW 2/10/2014 3

4 DRIVERS FOR VARIABLE TRANSFERS BPA 2010 Peak Load = 9,794 MW 2013 Peak Load = 10,639 MW 2010 Spring Min Load = 4,315 MW 2013 Spring Min Load = 4,424 MW Dec 2010 Installed Wind Gen = 3,297 MW Dec 2013 Installed Wind Gen = 5,000 MW Additional DTC Requests 2014 CAISO/PAC Energy Imbalance market (EIM) 2015/2016 NWPP EIM 2/10/2014 4

5 WHAT LED US HERE? What is DTC? Approach Unanswered Questions? DTC = Dynamic Transfer Capability Customer Impact Acceptable? Equipment Impact Acceptable? Operating Point Reliable? Allowable voltage variation? Elements that limit DTC? Increased wear and tear on equipment? How DTC limits change in real-time? 2/10/2014 5

6 FACTORS INFLUENCING VARIABLE TRANSFERS 2/10/2014 6

7 Transmission System Voltage (pu) DISTRIBUTION IMPACT MODELING ANSI DISTRIBUTION VOLTAGE STANDARD C84.1 ANSI Voltage Limits Voltage Level Min Per-Unit Voltage (pu) Max Per-Unit Voltage (pu) V Systems > 600 V Systems Typical Daily Voltage Variation on BPA System Hour Period 2/10/2014 7

8 VOLTAGE VARIATION As system loading increases, allowable voltage variation decreases As voltage variation increases, ANSI violations increase exponentially Additional regulation equipment relaxes limits at higher loading levels ANSI violations are dramatically reduced by additional regulation equipment Relaxed voltage limits come at the cost of increased wear on equipment 2/10/2014 8

9 ENERGY IMBALANCE MARKET Variable Transfer Limits Step 1: Historic Use Step 2: Static Nomogram Step 3: Real time calculations 2/10/2014 9

10 DTC Task Force HISTORIC USE Ramu Ramanathan 2/10/

11 5 min avg MW change Historic Variation Limit 98% variation SOL Path Flow Actual Flow Upper 5 min Flow Limit MW Schedule Flow Lower 5 min Flow Limit Time 2/10/

12 DTC Task Force STATIC NOMOGRAM Ramu Ramanathan 2/10/

13 DEVELOPMENT OF VTL NOMOGRAM SCADA Real Time Data State Estimation Power Flow Case Aux File Program Saved RT Cases Power System Variable Transfer Limit Calculation Case Selection Path Data 2/10/

14 STATIC VS. VARIABLE TRANSFER Sum of the variable transfers plus the static transfers on a path must be less than or equal to the SOL; ST + VT <= SOL 2/10/

15 VTL Variation SOL Path Flow Actual Flow Upper 5 min Flow Limit MW Schedule Flow Lower 5 min Flow Limit Time 2/10/

16 REAL TIME CALCULATIONS DTC Task Force Ramu Ramanathan 2/10/

17 VTL CALCULATIONS REAL TIME SCADA State Estimation Power Flow Case Real Time Data Power System Variable Transfer Limit Calculation Path Data 2/10/

18 ? DTC Task Force Ramu Ramanathan 2/10/

19 TECHNICAL PAPERS Transfer Variability and the Need for New Limits on the Grid, 2012 CIGRÉ Canada Conference, Montréal, Québec, September Methodology of Computing Simultaneous Variable Transfer Limits on Multiple Paths, 2012 CIGRÉ Grid of the Future Symposium, Kansas City, Oct Factors that Influence Variable Transfers UPEC Sept Calculating Variable Transfer Limits for Dynamic Transfers, 2013 CIGRÉ Grid of the Future Symposium, Boston, Oct An Analysis of the Impact of Transmission Level Voltage Variation on Distribution Feeder Power Quality. To Be Submitted 2/10/

20 REPORTS Powerex WAPA Columbia Grid SMUD Northern Tier TANC NWPP PSE Avista Task Force PGE BPA PAC BCH NWE CAISO Gaelectric IPCO MSR Reports Assessing the Impact of Dynamic Transfers on Transmission System Operation, Brian Tuck and R. Ramanathan, February 15, 2010 RD 237 Bidirectional Multipath Dynamic Transfer Analysis, Brian Tuck and R. Ramanathan Oct 6, 2012 Dynamic Transfer Capability Task Force Phase 1 Report, Wind Integration Study team, March 16, 2011 Dynamic Transfer Capability Task Force Phase 2 Report, Wind Integration Study team, July, 2011 Dynamic Transfer Capability Task Force Phase 3 Report, Wind Integration Study team, December, /10/