Current through Register Vol. 49, No. 6, March 15, 2024
PURPOSE: This rule sets minimum standards for the
maintenance and updating of historical data, the level of detail required in
analyzing loads, and the purposes to be accomplished by load analysis and by
load forecast models. The load analysis discussed in this rule is intended to
support both demand-side management efforts of
4 CSR
240-22.050 and the load forecast models of this rule.
This rule also sets the minimum standards for the documentation of the inputs,
components, and methods used to derive the load forecasts.
(1) Selecting Load Analysis Methods. The
utility may choose multiple methods of load analysis if it deems doing so is
necessary to achieve all of the purposes of load analysis and if the methods
are consistent with, and calibrated to, one another. The utility shall describe
and document its intended purposes for load analysis methods, why the selected
load analysis methods best fulfill those purposes, and how the load analysis
methods are consistent with one another and with the end-use consumption data
used in the demand-side analysis as described in
4 CSR
240-22.050. At a minimum, the load analysis methods
shall be selected to achieve the following purposes:
(A) To identify end-use measures that may be
potential demand-side resources, general-l y, those end-use measures with an
opportunity for energy and/or demand savings;
(B) To derive a data set of historical values
from load research data that can be used as dependent and independent variables
in the load forecasts;
(C) To
facilitate the analysis of impacts of implemented demand-side programs and
demand-side rates on the load forecasts and to augment measurement of the
effectiveness of demand-side resources necessary for
4 CSR
240-22.070(8) in the evaluation of
the performance of the demand-side programs or rates after they are
implemented; and
(D) To preserve,
in a historical database, the results of the load analysis used to perform the
demand-side analysis as described in
4 CSR
240-22.050, and the load forecasting described in
4 CSR
240-22.030.
(2) Historical Database for Load Analysis.
The utility shall develop and maintain data on the actual historical patterns
of energy usage within its service territory. The following information shall
be maintained and updated on an ongoing basis and described and documented in
the triennial compliance filings:
(A)
Customer Class Detail. At a minimum, the historical database shall be
maintained for each of the major classes;
(B) Load Data Detail. The historical load
database shall contain the following data:
1.
For each jurisdiction for which it prepares customer and energy and demand
forecasts, for each major class, to the actual monthly energy usage and number
of customers and weather-normalized monthly energy usage;
2. For each jurisdiction and major class,
estimated actual and weather-normalized demands at the time of monthly system
peaks; and
3. For the system,
actual and weather-normalized hourly net system load;
(C) Load Component Detail. The historical
database for major class monthly energy usage and demands at time of monthly
peaks shall be disaggregated into a number-of-units component and a
use-per-unit component, for both actual and weather-normalized loads.
1. The number-of-units component shall be the
number of customers, square feet, devices, or other units as appropriate to the
customer class and the load analysis method selected by the utility. The
utility shall select the units component with the intent of providing
meaningful load analysis for demand-side analysis and maintaining the integrity
of the database over time.
2. The
utility shall develop and implement a procedure to routinely measure and
regularly update estimates of the effect of departures from normal weather on
class and system electric loads. The estimates of the effect of weather on
historical major class and system loads shall incorporate the nonlinear
response of loads to daily weather and seasonal variations in loads.
3. The utility shall describe and document
the methods used to develop weather measures and the methods used to estimate
the effect of weather on electric loads. If statistical models are used, the
documentation shall include at least: the functional form of the models; the
estimation techniques employed; and the relevant statistical results of the
models, including parameter estimates and tests of statistical significance.
The data used to estimate the models, including the development of model input
data from basic data, shall be included in the workpapers supplied at the time
the compliance report is filed;
(D) For each major class specified pursuant
to subsection (2)(A), the utility shall provide, on a seasonal and annual basis
for each year of the historical period-
1. Its
assessment of the historical end-use drivers of energy usage and peak demand,
including trends in numbers of units and energy consumption per unit;
2. Its assessment of the weather sensitivity
of energy and peak demand; and
3.
Plots illustrating trends materially affecting electricity consumption over the
historical period;
(E)
The utility shall describe and document any adjustments that it made to
historical data prior to using it in its development or interpretation of the
forecasting models; and
(F) Length
of Historical Database. The utility shall develop and retain the historical
database over the historical period.
(3) Analysis of Number of Units. For each
major class, the utility shall describe and document its analysis of the
historical relationship between the number of units and the economic and/or
demographic factors (explanatory variables) that affect the number of units for
that major class. The analysis may incorporate or substitute the results of
secondary analyses, with the proviso that the utility analyze and verify the
applicability of those results to its service territory. If the utility
develops primary analyses, or to the extent they are available from secondary
analyses, these relationships shall be specified as statistical or mathematical
models that relate the number of units to the explanatory variables.
(A) Choice of Explanatory Variables. The
utility shall identify appropriate explanatory variables as predictors of the
number of units for each major class. The critical assumptions that influence
the explanatory variables shall also be identified and documented.
(B) Documentation of statistical models shall
include the elements specified in subsection (2)(C) of this rule. Documentation
of mathematical models shall include a specification of the functional form of
the equations if the utility develops primary analyses, or to the extent they
are available if the utility incorporates secondary analyses.
(4) Analysis of Use Per Unit. For
each major class, the utility shall describe and document its analysis of
historical use per unit by end use.
(A)
End-Use Load Detail. For each major class, use per unit shall be disaggregated,
where information permits, by end-uses that contribute significantly to energy
use or peak demand.
1. The utility shall
consider developing information on at least the following end-use loads:
A. For the residential sector: lighting,
space cooling, space heating, ventilation, water heating, refrigerators,
freezers, cooking, clothes washers, clothes dryers, television, personal
computers, furnace fans, plug loads, and other uses;
B. For the commercial sector: space heat,
space cooling, ventilation, water heat, refrigeration, lighting, office
equipment, cooking equipment, and other uses; and
C. For the industrial sector: machine drives,
space heat, space cooling, ventilation, lighting, process heating, and other
uses.
2. The utility may
modify the end-use loads specified in paragraph (4)(A)1.
A. The utility may remove or consolidate the
specified end-use loads if it determines that a specified end-use load is not
contributing, and is not likely to contribute in the future, significantly to
energy use or peak demand in a major class.
B. The utility shall add to the specified
end-use loads if it determines that an end-use load currently not specified is
likely to contribute significantly to energy use or peak demand in a major
class.
C. The utility shall provide
documentation of its decision to modify the specified end-use loads for which
information is developed, as well as an assessment of how the modifications can
be made to best preserve the continuity and integrity of the end-use load
database.
3. For each
major class and each end-use load, including those listed in paragraph
(4)(A)1., if information is not available, the utility shall provide a schedule
for acquiring this end-use load information or demonstrate that either the
expected costs of acquisition were found to outweigh the expected benefits over
the planning horizon or that gathering the end-use load information has proven
to be infeasible.
4. The utility
shall determine the effect that weather has on the total load of each major
class by disaggregating the load into its cooling, heating, and
non-weather-sensitive components. If the cooling or heating components are a
significant portion of the total load of the major class, then the cooling or
heating components of that load shall be designated as end uses for that major
class.
(B) The database
and historical analysis required for each end use shall be developed from a
utility-specific survey or other primary data. The database and analysis may
incorporate or substitute the results of secondary data, with the proviso that
the utility analyze and verify the applicability of those results to its
service territory. The database and historical analysis required for each end
use shall include at least the following:
1.
Measures of the stock of energy-using capital goods. For each major class and
end-use load identified in subsection (4)(A), the utility shall implement a
procedure to develop and maintain adequate data on the energy-related
characteristics of the building, appliance, and equipment stock including
saturation levels, efficiency levels, and sizes, where applicable. The utility
shall update the data before each triennial compliance filing; and
2. Estimates of end-use energy and demand.
For the end-use loads identified in subsection (4)(A), the utility shall
estimate monthly energies and demands at the time of monthly system peaks and
shall calibrate these energies and demands to equal the weather-normalized
monthly energies and demands at the time of monthly peaks for each major class
for the most recently available data.
(5) Selecting Load Forecasting Models. The
utility shall select load forecast models and develop the historical database
needed to support the selected models. The selected load forecast models will
include a method of end-use load analysis for at least the residential and
small commercial classes, unless the utility demonstrates that end-use load
methods are not practicable and provides documentation that other methods are
at a minimum comparable to end-use methods. The utility may choose multiple
models and methods if it deems doing so is necessary to achieve all of the
purposes of load forecasting and if the methods and models are consistent with,
and calibrated to, one another. The utility shall describe and document its
intended purposes for load forecast models, why the selected load forecast
models best fulfill those purposes, and how the load forecast models are
consistent with one another and with the end-use usage data used in the
demand-side analysis as described in
4 CSR
240-22.050. As a minimum, the load forecast models
shall be selected to achieve the following purposes:
(A) Assessment of consumption drivers and
customer usage patterns-to better understand customer preferences and their
impacts on future energy and demand requirements, including weather sensitivity
of load;
(B) Long-term load
forecasts-to serve as a basis for planning capacity and energy service needs.
This can be served by any forecasting method or methods that produce reasonable
projections (based on comparing model projections of loads to actual loads) of
future demand and energy loads;
(C)
Policy analysis-to assess the impact of legal mandates, economic policies, and
rate designs on future energy and demand requirements. The utility may use any
load forecasting method or methods that it demonstrates can adequately analyze
the impacts of legal mandates, economic policies, and rate designs.
(6) Load Forecasting Model
Specifications.
(A) For each load forecasting
model selected by the utility pursuant to section
4 CSR
240-22.030(5), the utility shall
describe and document its-
1. Determination
of appropriate independent variables as predictors of energy and peak demand
for each major class. The critical assumptions that influence the independent
variables shall also be identified.
A. The
utility shall assess the applicability of the historical explanatory variables
pursuant to subsection (3)(A) to its selected forecast model.
B. To the extent that the independent
variables selected by the utility differ from the historical explanatory
variables, the utility shall describe and document those
differences;
2.
Development of any mathematical or statistical equations comprising the load
forecast models, including a specification of the functional form of the
equations; and 3. Assessment of the applicability of any load forecast models
or portions of models that were utilized by the utility but developed by
others, including a specification of the functional forms of any equations or
models, to the extent they are available.
(B) If the utility selects load forecast
models that include end-use load methods, the utility shall describe and
document any deviations in the independent variables or functional forms of the
equations from those derived from load analysis in sections (3) and
(4).
(C) Historical Database for
Load Forecasting. In addition to the load analysis database, the utility shall
develop and maintain a database consistent with and as needed to run each
forecast model utilized by the utility. The utility shall describe and document
its load forecasting historical database in the triennial compliance filings.
As a minimum, the utility shall-
1. Develop
and maintain a data set of historical values for each independent variable of
each forecast model. The historical values for each independent variable shall
be collected for a period of ten (10) years, or such period deemed sufficient
to allow the independent variables to be accurately forecasted over the entire
planning horizon;
2. Explain any
adjustments that it made to historical data prior to using it in its
development of the forecasting models;
3. Archive previous projections of all
independent variables used in the energy usage and peak load forecasts made in
at least the past ten (10) years and provide a comparison of the historical
projected values in prior plan filings to actual historical values and to
projected values in the current compliance filing; and
4. Archive all previous forecasts of energy
and peak demand, including the final data sets used to develop the forecasts,
made in at least the past ten (10) years. Provide a comparison of the
historical final forecasts to the actual historical energy and peak demands and
to the current forecasts in the current triennial compliance
filing.
(7)
Base-Case Load Forecast. The utility's base-case load forecast shall be based
on projections of the independent variables that utility decision-makers
believe to be most likely. All components of the base-case load forecast shall
assume normal weather conditions. The load impacts of implemented demand-side
programs and rates shall be incorporated in the base-case load forecast, but
the load impacts of proposed demand-side programs and rates shall not be
included in the base-case forecast.
(A) Major
Class and Total Load Detail. The utility shall produce forecasts of monthly
energy usage and demands at the time of the summer and winter system peaks by
major class for each year of the planning horizon, and shall describe and
document those forecasts in its triennial compliance filings. Where applicable,
these major class forecasts shall be separated into their jurisdictional
components.
1. The utility shall describe and
document how the base-case forecasts of energy usage and demands have taken
into account the effects of real prices of electricity, real prices of
competitive energy sources, real incomes, and any other relevant economic and
demographic factors. If the methodology does not incorporate economic and
demographic factors, the utility shall explain how it accounted for the effects
of these factors.
2. The utility
shall describe and document how the forecasts of energy usage and demands have
taken into account the effects of legal mandates affecting the consumption of
electricity.
3. The utility shall
describe and document how the forecasts of energy usage and demands are
consistent with trends in historical consumption patterns, end uses, and
end-use efficiency in the utility's service area as identified pursuant to
sections 4
CSR 240-22.030(2), (3), and
(4).
4. For at least the base year
of the forecast, the utility shall describe and document its estimates of the
monthly cooling, heating, and non-weather-sensitive components of the
weather-normalized major class loads.
5. Where judgment has been applied to modify
the results of its energy and peak forecast models, the utility shall describe
and document the factors which caused the modification and how those factors
were quantified.
6. For each major
class specified pursuant to subsection (2)(A), the utility shall provide plots
of class monthly energy and coincident peak demand at the time of summer and
winter system peaks. The plots shall cover the historical database period and
the forecast period of at least twenty (20) years. The plots of coincident peak
demands for the historical period shall include both actual and
weather-normalized peak demands at the time of summer and winter system peaks.
The plots of coincident peak demand for the forecast period shall show the
class coincident demands for the base-case forecast at the time of summer and
winter system peaks.
7. The utility
shall provide plots of the net system load profiles for the summer peak day and
the winter peak day showing the contribution of each major class. The plots
shall be provided in the triennial filing for the base year of the forecast and
for the fifth, tenth, and twentieth years of the forecast. Plots for all years
shall be included in the workpapers supplied at the time of the triennial
filing.
(B) Forecasts of
Independent Variables. The forecasts of independent variables shall be
specified, described, and documented.
1.
Documentation of mathematical models developed by the utility to forecast the
independent variables shall include the reasons the utility selected the models
as well as specification of the functional form of the equations.
2. If the utility adopted forecasts of
independent variables developed by another entity, documentation shall include
the reasons the utility selected those forecasts, an analysis showing that the
forecasts are applicable to the utility's service territory, and, if available,
a specification of the functional form of the equations used to forecast the
independent variables.
3. These
forecasts of independent variables shall be compared to historical trends in
the variables, and significant differences between the forecasts and long-term
and recent trends shall be analyzed and explained.
4. Where judgment has been applied to modify
the results of a statistical or mathematical model, the utility shall specify
the factors which caused the modification and shall explain how those factors
were quantified.
(C) Net
System Load Forecast. The utility shall produce a forecast of net system load
profiles for each year of the planning horizon. The net system load forecast
shall be consistent with the utility's forecasts of monthly energy and peak
demands at time of summer and winter system peaks for each major
class.
(8) Load Forecast
Sensitivity Analysis. The utility shall describe and document its analysis of
the sensitivity of the dependent variables of the base-case forecast for each
major class to variations in the independent variables identified in subsection
4 CSR
240-22.030(6)(A).
(A) The utility shall produce at least two
(2) additional normal weather load forecasts (a high-growth case and a
low-growth case) that bracket the base-case load forecast. Subjective
probabilities shall be assigned to each of the load forecast cases. These
forecasts and associated subjective probabilities shall be used as inputs to
the risk analysis required by
4 CSR
240-22.060.
(B) The utility shall estimate the
sensitivity of system peak load forecasts to extreme weather conditions. This
information shall be considered by utility decision-makers to assess the
ability of alternative resource plans to serve load under extreme weather
conditions when selecting the preferred resource plan pursuant to
4 CSR
240-22.070(1).
(C) The utility shall provide plots of energy
usage and peak demand covering the historical database period and the forecast
period of at least twenty (20) years.
1. The
energy plots shall include the summer, non-summer, and total energy usage for
each calendar year. The peak demand plots shall include the summer and winter
peak demands.
2. The historical
period shall include both actual and weather-normalized values. The forecast
period shall include the base-case, low-case, and high-case
forecasts.
*Original authority: 386.040, RSMo 1939; 386.250, RSMo
1939, amended 1963, 1967, 1977, 1980, 1987, 1988, 1991, 1993, 1995, 1996;
386.610, RSMo 1939; and 393.140, RSMo 1939, amended 1949,
1967.
