Short Term and Mid Term Load Forecast

John DumasSupervisor, Operations Planning

ERCOTJanuary 24, 2007

2

ERCOT Load Forecasts

• ERCOT uses three primary types of load forecast.– Long Term – Mid Term– Short Term

• This presentation will cover only short term and mid term load forecast.

3

Short Term Load Forecast

• Period covered:– Every 5 minute period for the next hour.– The STLF program runs every 5 minutes.

• Used for:– Determining Balancing Energy deployments 25 minutes prior to

the start of the interval.

• Developed by AREVA

4

STLF Error

Month

MAPE for STLF run at 40 min Ahead (2005)

MAPE for STLF run at 40 min Ahead (2006)

January 0.77 0.86

February 1.24 0.81

March 0.77 0.72

April 0.78 1.68

May 0.73 1.27

June 0.51 0.54

July 0.57 0.51

August 0.58 0.53

September 0.63 0.71

October 0.75 0.75

November 0.77 0.79

December 0.78 0.74

Average MAPE for Year 0.74 0.83

5

Mid Term Load Forecast

• Period covered:– Each hour period for the next 7 days.– The MTLF program runs every hour.

• Used for:– Day Ahead reliability studies.– Decisions on Unit Commitment

• OOMC• Replacement Reserve

• Developed by:– AREVA– PRT

6

MTLF Error

Month

MAPE for MTLF run at 16:00 Day Ahead

(2004)

MAPE for MTLF run at 16:00 Day Ahead

(2005)

MAPE for MTLF run at 16:00 Day Ahead

(2006)

MAPE for MTLF run at 16:00 Day Ahead (2006) with Standard Deviation

January 4.76 5.02 4.79 N/A

February 4.81 3.47 4.81 N/A

March 2.89 3.41 4.95 N/A

April 3.23 3.37 5.59 N/A

May 3.93 4.21 3.59 N/A

June 4.85 3.91 2.65 3.46

July 5.07 5.22 2.62 3.29

August 4.10 4.86 2.09 2.61

September 3.66 6.24 4.03 N/A

October 3.85 4.51 3.63 N/A

November 3.60 4.53 3.28 N/A

December 4.18 5.95 3.44 N/A

Average MAPE for Year 4.08 4.56 3.79 N/A

7

Causes of MTLF Error

• Error in Weather Forecast– Temperature– Humidity– Wind Chill– No good way to account for probability of rain

• Load Response– May be based on energy cost (MCP) or 4CP anticipation– ERCOT has limited knowledge of this behavior

8

January 15, 2007

MTLF Day Ahead 16:00 MAPE: 5.84

01-15-2007 LOAD FORECAST VS ACTUAL LOAD

0

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ER

RO

R %

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45000

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MW

APE %

SUM(FORECASTMW)

ACTUAL

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January 15, 2007

01-15-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR COAST

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ACTUALLOAD

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January 15, 2007

01-15-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR NORTH_C

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January 15, 2007

01-15-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR SOUTH_C

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January 16, 2007MTLF Day Ahead 16:00 MAPE: 6.0

01-16-2007 LOAD FORECAST VS ACTUAL LOAD

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:0012

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APE %

SUM(FORECASTMW)

ACTUAL

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January 16, 2007

01-16-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR COAST

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ACTUALLOAD

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January 16, 2007

01-16-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR NORTH_C

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ACTUAL TEMP

FORECAST MW

ACTUALLOAD

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January 16, 2007

01-16-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR SOUTH_C

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January 17, 2007MTLF Day Ahead 16:00 MAPE: 2.63

01-17-2007 LOAD FORECAST VS ACTUAL LOAD

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HOURS

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RO

R %

30000

35000

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MW

APE

SUM(FORECASTMW)

ACTUAL LOAD

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January 17, 2007

01-17-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR COAST

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ACTUAL TEMP

FORECAST MW

ACTUALLOAD

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January 17, 2007

01-17-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR NORTH_C

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FORECAST MW

ACTUALLOAD

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January 17, 2007

01-17-2007 LOAD FORECAST ANALYSIS WITH TEMPERATURE FOR SOUTH_C

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FORECAST MW

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