No comment. 

No comments

Why is the P(50) Load methodology different for Summer vs Winter?

The spreadsheet is very helpful for walking through the calculation so we really appreciate that.

• Winter P50 Peak Load Forecast: While the Super Peak months (name needs to be changed) balances three months across the winter well, can we show how the methodology can account for all load peaking at the same time (e.g. MLK weekend or June heat dome)?

SRP appreciates BPM 103 including the methodology for the P50 Peak Load Forecast but requests further clarity on the integration of a load growth factor. It is not clear if the load growth factor should be applied to the forecast for the upcoming (current) forecast year or only for years further out in the forecast horizon (future years). The current methodology suggests using the median of the last 5 years as the forecast, which may underestimate future loads for growing systems. SRP believes that the upcoming (current) forecast year forecast value should also have the annual growth factor applied to it. SRP recommends detailing in the BPM how and when to apply the load growth factor in the provided examples. Additionally, extending the examples through all steps (1-6) will provide more transparency and clarity for participants.

No additional comments at this time.

Comment applies to both sections 4.1 and 4.2: Tacoma Power is concerned that limiting the Monthly P50 Peak Load Forecast methodology to just five seasons with a single datapoint for each will either under- or over-estimate a participant’s load from year to year. Tacoma has used the current methodology in order to predict its P50 Peak Load Forecast in future seasons and anticipates a sudden substantial change to the resulting P50 that does not necessarily reflect the change in Tacoma’s load.

Tacoma Power supports the reasoning behind using the median over the mean (median being resistant to outliers). But paired with the small sample size the median can also produce skewed results.

Tacoma Power does not have an alternate proposal at this time but would be interested in refining the methodology in the future with the aim of producing more consistent results from year to year.

Regarding modifying the P50 Peak Load Forecast results to account for load removal or addition: Would incorporating the change in load into the historical data be a valid way to calculate the max for each season and the median for the five-year period? Rather than applying a modifier to Monthly P50 results calculated using unaltered historical data?