The
October 24, 2002 System Analysis Advisory Committee meeting, held at the
Northwest Power Planning Council's offices in Portland, Oregon, was
chaired by Michael Schilmoeller of the Council staff.
The
following is a distillation (not a verbatim transcript) of items discussed
during the call, together with actions taken on those items. Please
note that some enclosures referenced in the body of the text may be too
lengthy to attach; all enclosures referenced are available upon request
from Schilmoeller at 503/820-2314.
Schilmoeller welcomed everyone to today's meeting, led a round of
introductions, then reviewed today's agenda. Schilmoeller noted that
copies of his presentation are available via the NWPPC website; please
refer to this document for full details, including graphs and
charts.
The
draft minutes from the October 4 SAAC meeting were approved as written.
Schilmoeller began with a presentation on ?Price Processes? (slides
1-5), discussing the problem, a potential solution, and the concept of
Geometric Brownian Motion (GBM), among other topics.
that's
well and good, depending on what time scales you?re working with, said
David Engberg ? what about the other tools you can use? When we look at
price behavior of commodities, hydro and loads, we will be interested in
coming up with a more accurate model of what those behaviors are,
Schilmoeller replied ? it would certainly be appropriate, at that time,
to consider those other tools.
Schilmoeller then moved on to the area of ?Thermal Generation ?
Objectives:?
1.
We need a way to quickly estimate the dispatch factor for thermal
generation, so that we can calculate variable cost.
2.
Should have certain basic properties
3.
If average monthly prices ($/Mwh) for gas are about the same as average
monthly prices for electricity, the dispatch factor should be about 50
percent
4.
If average monthly prices ($/Mwh) for gas are well above the average
monthly prices for electricity, but there is a good deal of uncertainty
in the prices, the plant should dispatch, albeit a small amount.
5.
If average monthly prices ($/Mwh) for gas are well below the average
monthly price for electricity, but there is a good deal of uncertainty
about the prices, the plant should run close to, but not quite 100%
capacity factor (disregarding maintenance and forced outage)
So
the resources you?re assuming here do not affect the price of
electricity? Michael McCoy asked. Correct, Schilmoeller replied ? we're
modeling an open system, rather than a closed system. We will use tools
like AURORA and GENESYS to inform us about what those cost factors might
be, he said. So you?re assuming that there is little correlation
between the price of thermal generation and the price of electricity? a
BPA representative asked. Correct, Schilmoeller replied. So there is
some residual amount of generation being left for the daily market? the
BPA representative asked. The model assumes that power plants are
dispatched for spot prices, Schilmoeller replied. We can represent those
types of commitments, but there will also be contracts for managing
financial risk, he said. And this model can address thermal resources
other than gas, such as coal? another participant asked. Yes,
Schilmoeller replied ? we should be able to disaggregate those plants
into what is committable and what is not. You don't break that out,
currently? the participant asked. Correct, said Schilmoeller.
Next, Schilmoeller put up a sample analysis in the form of a graph,
titled ?Typical Dispatchable? ? example of 1 MW single-cycle
combustion turbine (no dispatch constraints), Natural gas price: $3.33/MBTU,
Heat rate: 9,000 BTU/kWH) etc. He then proceeded onward through a series
of slides illustrating other aspects of how the portfolio model deals
with thermal generation, including the Price Duration Curve, variability
viewed as Cumulative Probability Density Function (CDF), and various
potential simplifications to this facet of the analysis.
Some have suggested that ramping periods have higher volatility than
peak periods, said McCoy ? that creates a small issue you might want
to give some thought to. Good suggestion, said Schilmoeller.
The group devoted a few minutes of discussion to the technical nuances
of Simplifications 1 and 2, with Schilmoeller fielding a variety of
detailed questions and comments. Ultimately, he said he welcomes such
discussion, and invited the other SAAC participants to contact him
outside of today's meeting if they have further concerns.
In
response to a question from Oliver, Schilmoeller reiterated that the
portfolio model is intended to provide only a snapshot in time, not a
time-sequence of prices. Next, he put up slides titled ?Almost
There...? ?Option Delta: and ?The Payoff (equation)?
However, said Schilmoeller, two issues remain: gas prices are not
constant (the strike price X is not fixed). Also, most of what we may
think we know about future price uncertainty might be expressed in terms
of average monthly prices. The solution, he said, is to
1.
Use a European ?spread? option instead of a standard European call
option. Also,
2.
Try to estimate the volatility of the hourly spread from the monthly
volatilities and correlations.
After a break, Schilmoeller returned to the topic of Geometric Brownian
Motion (GBM), discussing the probability distribution it generates with
respect to future pricing. The group devoted a few minutes of discussion
to the technical nuances of this portion of the model.
Schilmoeller then moved on to the topics of ?European Spread Option?
and ?Hourly Volatiles from Monthly.? He finished this portion of the
agenda with an example capacity factor calculation employing the
principals laid out over the course of the morning.
Essentially, he said, we want a dispatch that gives us a capacity factor
of about 50%; you?re never going to dispatch 100% of the time. We
commandeered some of the algebra in the Black-Scholes model, setting r
at zero, for example. We'll dig into this further at our next meeting,
when we will be discussing electricity prices, Schilmoeller said. Does
everyone understand the logic that went into this model? he asked. So
far, was the reply.
5. Metrics.
This will be more of a free-form discussion, Schilmoeller said;
essentially, I would like the help of this group in developing a risk
metric for the region. In my view, this metric should be minimum total
power cost, driven by a CVaR conversion.
Schilmoeller touched on stakeholder issues, including a list of proposed
stakeholders and a proposed stakeholder perspective. He then moved on to
a list of potential metric candidates, including value at risk (VaR),
standard deviation, expected shortfall, conditional VaR (CVaR), Van
Neumann utility functions and block maxima. Next, Schilmoeller touched
on a series of graphs illustrating how these various metrics work.
The group devoted a few minutes of discussion to these metrics, debating
their coherence, distributions and other factors. Schilmoeller said
that, in his opinion, CVaR and block maxima offer the most potential
upside; the people at Crystal Ball have told him that it should be
possible to incorporate CVaR into the Crystal Ball computer tool.
What about seasonal exchanges, and streamflow ?trenches?? asked
McCoy. Selling deep in a money call is another way to sell off the
upside ? I agree, said Schilmoeller. I'm concerned that a lot of
this gets back to the point that we have random prices here, said the
BPA representative ? many of these CVaR assumptions make sense only if
you assume random prices. It is a bit confusing, another participant
noted. The group also discussed the current status of the energy market,
and its impact on the feasibility of this approach. One participant
noted that the energy trading market is currently at its lowest ebb in
years; however, two years from now, the market will almost certainly be
substantially different.
Schilmoeller noted that this entire presentation is available via the
SAAR website, including the final slide from this section, titled ?Conclusions.?
6. Representations In the Portfolio Model ? Plan
Issues, Price Responsive Demand.
This topic was not explicitly discussed at today's meeting.
7. Next SAAC Meeting Date.
The next meeting of the System Analysis Advisory Committee was set for
Friday, November 22, beginning at 9:30; the main topics discussed at
this meeting will be electricity prices and hydrogeneration.
Schilmoeller asked that, if any of the other SAAC participants know of
good sources of hourly electricity prices, that they provide that
information to him. Meeting summary prepared by Jeff Kuechle, NWPPC
contractor.