A Revised Resource Adequacy Standard for the Pacific Northwest. NERC LOLE Work Group November 7-8, 2011 Austin, TX

Transcription

1 A Revised Resource Adequacy Standard for the Pacific Northwest NERC LOLE Work Group November 7-8, 2011 Austin, TX

2 OUTLINE Makeup of the PNW s Power Supply NERC Definition for Adequacy PNW s Approach Sample Report For Illustration Only 2

3 RESOURCE MIX IN THE NORTHWEST Gas 59,800 MW Capacity Wind 10 Coal Hydro 57 Hydro Geothermal Coal Biomass Wind Pump Storage Nuclear Gas Peak Gas CHP Gas Comb Cycle 3

4 Volume (Maf) RESERVOIR STORAGE & RUNOFF VOLUMES Wet (193) 100 Avg (134) 50 0 Dry (78) Annual Runoff Canada USA Storage 4

5 Average Megawatts VARIABILITY IN HYDROELECTRIC GENERATION 25,000 20,000 15,000 10,000 5, % of NW electricity driest year D R Y 75% of NW electricity on average A V E R A G E Dry Average Wet Load W E T D E M A N D 5

6 PNW POWER SUPPLY Large hydro component Historically energy (water) limited Insufficient storage to plan for average hydro Recent changes Lots of new wind (near 6K capacity) Increasing summer peak loads Increasing constraints on hydro system Summer and winter concerns Energy and capacity issues 6

7 NERC DEFINITION FOR ADEQUACY 1 Adequacy is the ability of the electric system to supply the aggregate electric power and energy requirements of the electricity consumers at all times, taking into account scheduled and reasonably expected unscheduled outages of system components

8 OBSERVATIONS AND QUESTIONS What does at all times mean? Should targets for LOLE and other adequacy metrics be zero? Only the scheduled and reasonably expected unscheduled outages of system components should be taken into account. What about variations in temperature and wind generation? In our case, what about fuel (water) supply? For the PNW, water supply is the largest 8

9 OBSERVATIONS AND QUESTIONS If LOLE is calculated with different random variables (more than just FOR) in different regions, how can those values be compared? What does the 2.4 hours/year mean? If this came from the 1-day-in-10 year limit, doesn t it imply a 24-hour shortfall? Wasn t the original intention 1-event-in-10 years? If so, then the 2.4 hours/year is then less restrictive than the 1-day-in-10 years. 9

10 THE PNW S APPROACH Use a chronological hourly simulation model Incorporate 4 random variables Water supply Temperature variation Wind generation Forced outages Include some level of market supply 10

11 THE PNW S APPROACH Standby resources are resources and DSM actions that are contractually available but which are only intended to be used during periods of stress Any game (year) in which the simulated shortfalls exceed the capabilities of the standby resources at least once is deemed a bad game LOLP = number of bad games divided by the total number of games The LOLP threshold is set to 5% 11

12 INTERPRETATION The likelihood of some future year having at least one unwanted event must be 5% or less for the power supply to be deemed adequate. Does not take economic and other factors into consideration, thus will not necessarily reflect a cost effective power supply Tends to depend more on market supply than most utilities are willing to 12

13 INTERPRETATION Intended to be a smoke alarm to indicate when supply falls dangerously short Not intended as a resource needs assessment However, can be used to support a needs assessment by changing assumptions regarding market supply and standby resources Also produce a report with statistical data 13

14 STATE OF THE SYSTEM REPORT More valuable than the adequacy assessment Other commonly used adequacy measures Reliance on market and standby resources Monthly assessment of potential shortfalls Frequency, duration and magnitude of events Conditions under which events occur 14

15 SAMPLE REPORT FOR ILLUSTRATION ONLY 1 Not an official assessment LOLP is 6.7% = inadequate supply Dec, Jan and Aug only months with shortfalls LOLP driven by peak shortfalls in August Adding 400 MW of capacity in August will bring LOLP below 5% 1 Chose an inadequate supply to ensure that we had some numbers to show. 15

16 ADEQUACY METRICS AND VALUES Adequacy Metrics Metric LOLP DR and SR CVaR (energy) CVaR (peak) EUE LOLE Description Loss of load probability = number of games with a problem divided by the total number of games Demand response and standby resources that are contractually available = measure of Conditional value at risk = average annual curtailment for 5% worst games Conditional value at risk = average single-hour curtailment for worst 5% of games Expected unserved energy = total curtailment divided by the total number of games Loss of load expectation = total number of hours of curtailment divided by total number of games 16

17 ADEQUACY METRICS AND VALUES Adequacy Metrics Metric LOLP Use of DR and SR CVaR (energy) CVaR (peak) EUE LOLE Value Units 6.7 Percent 8.6 Percent 67,618 MW-hours 2,277 MW 3,399 MW-hours 3.3 Hours/year For Illustration Only 17

18 ANNUAL HIGHEST HOUR PEAK CURTAILMENT For Illustration Only 18

19 MARKET RESOURCES: % OF TIME USED For Illustration Only 19

20 MARKET RESOURCES: DISPATCH For Illustration Only 20

21 INDEPENDENT POWER PRODUCERS For Illustration Only 21

22 SW MARKET PURCHASES For Illustration Only 22

23 PEAK DR, SR AND LOLP For Illustration Only 23

24 For Illustration Only CURTAILMENT STATISTICS Expected Number of Events per year Average Event Duration 14 Hours Average Event Magnitude MW-hrs Average Event Peak Shortfall 1098 MW Expected Number of Shortfall Hours 3.3 per year Percent of Games With an Event 8.6 percent 1 An event is defined as a contiguous set of hours of shortfall. 24