Probabilistic Forecasting Methods for System-Level Electricity Load Forecasting Philipp Giese

2025-05-02 0 0 322.25KB 7 页 10玖币
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Probabilistic Forecasting Methods for System-Level
Electricity Load Forecasting
Philipp Giese
Technische Universit¨
at Berlin
Berlin, Germany
Philipp.Giese@campus.tu-berlin.de
Abstract—Load forecasts have become an integral part of
energy security. Due to the various influencing factors that can
be considered in such a forecast, there is also a wide range of
models that attempt to integrate these parameters into a system
in various ways. Due to the growing importance of probabilistic
load forecast models, different approaches are presented in this
analysis. The focus is on different models from the short-term
sector. After that, another model from the long-term sector is
presented. Then, the presented models are put in relation to
each other and examined with reference to advantages and
disadvantages. Afterwards, the presented papers are analyzed
with focus on their comparability to each other. Finally, an
outlook on further areas of development in the literature will
be discussed.
Index Terms—probabilistic load forecast, analyzing, short-
term, comparability,
I. INTRODUCTION
Many fundamental power system optimization problems
such as the unit commitment problem [1] take system load
and renewable generation as inputs [2] [3]. In recent years,
stochastic optimization [4], robust optimization, [5] and
distributionally robust optimization [6], [7] models have been
applied to solve the unit commitment problem. However, these
models require a probabilistic representation of uncertain
load and renewable generation, and thus deterministic,
point forecasts are not compatible with these optimization
models.Improving a prediction by as little as one percent can
reduce electrical costs by millions of dollars in a case of
10,000 MW [8].
On the other hand, the advances in machine learning models
have brought forth various successful deterministic forecasting
models for different power systems applications, including
load forecasting [9], PV forecasting [10], net load ramp
forecasting [11], and power system frequency forecasting
[12]. However, these models are primarily point forecasts,
which lack a comprehensive representation of the uncertainty.
The analysis of this work is structured as follows: In the
next section different models for the calculation of probabilis-
tic load forecasting from the literature are presented. Here,
the focus is especially on the basic functionality and less
on mathematical derivations. In this section, especially the
different approaches in the short-term sector are highlighted.
Afterwards, another model from the long-term sector is pre-
sented. In the following section, the problem of comparability
is discussed. Based on the article by T.Hong et at [8], the
previously presented papers are analyzed with focus on their
comparability. Finally, the results are summarized.
II. PROBILISTIC FORECASTING MODELS
The short-term methods aim to provide the most accurate
forecast possible for a brief period of time. Due to the
increasing number of available smart devices, it is becoming
increasingly difficult to obtain precise loads forecasts based
only on weather data. Therefore, short-term forecast become
more important. In the following, different approaches are
shown which generate various forecast models because of
different regression models and machine learning. After that,
a probabilistic forecasting model is generated from the indi-
vidual models.
A. Combining Probabilistic Load Forecast
The approach described by Wang et al [16] aims to
generate different probabilistic load forecast models in the
first step and to combine them in a common model in the
second step. For the generation of combined forecast models,
this approach mainly deals with 2 problems: On the one
hand, the goal is to generate different forecasts. For this
purpose, a large variance of features must be integrated to
allow inclusion of various uncertainty factors. For this step
different established quantile regression models are used. This
type of regression describes the data based on a probability
distribution: how likely is it that data is within a specific
range, so-called quantiles? To determine these, the article
cites several types. Neural networks and various types of
decision trees are given as examples. These will be trained
with the help of machine learning. The methods discussed in
the next section also use machine learning in different forms.
Most of the dataset is used to train the developed models.
In this section, the model is given the input parameters and
the output parameters to be achieved, from which the model
infers in which cases which decisions must be made. Based
on this, edge weights within the model are optimized so that
the input parameters lead to the desired output parameters.
The training database is divided into 4 parts. The first 3
sections are used for individual model training and the last
section for combined model training. For individual training,
arXiv:2210.09399v1 [cs.LG] 17 Oct 2022
Fig. 1. Splitting of the training data sets [16]
the sections are used as follows: A part of the training data is
used for the adjustment of the single models generated by the
regression. The further data sets are used for the following
validation and testing of the model [16]. It is also possible to
reuse for validation the original training data in the form of
a sliding window [14].
The second phase of this system deals with the combination
of the generated models based on the corresponding model
weights. Here, the biggest problem is which combination is
the optimal one. For the combinations, different factors, such
as accuracy and uncertainty of the distribution, are considered.
To this purpose, error measuring functions, such as pinball lose
function, are used [16].
B. Feature Integration
1) Short Description: This approach, published by Chang
et al [13], generates suitable probabilistic load forecast models
based on the selection of a wide variety of data feature
combinations. A 2-stage method plus a subsequent test series
is applied. The main function of this model is that in the first
stage of this 2-stage model all investigated point load forecast
models can be integrated into the model independent of their
own features. After that, a corresponding probabilistic model
can be generated from the point forecasts by selecting the
required features. In the stages 1 and 2 the system trains on the
one hand the calculation of the individual point load forecast
and on the other hand the recognition of the corresponding
features. Summarized, the individual point load forecast curves
result in the probabilistic intervals.
2) Functionality: In the first stage, the individual models
for the calculation of point forecast are trained with historical
data. The models used were developed for various situations.
Accordingly, the models are based on different inputs and
features. Consequently, it is not guaranteed that the outputs
of the corresponding models have the same dimensions. In
this form the point load forecasts cannot be transformed into
probabilistic models. Therefore, a particularly important step
in this model is the detection and selection of the important
features or parameters of the individual models, which serve
as a foundation for the calculation of the probabilistic forecast
model. The selection of the features can be trained by using
Fig. 2. Functionality features interation [13]
different machine learning methods.
In the second stage, by selecting the features, the matching
point load forecast models are merged and together produce
the probabilistic forecast model. For the generation of point
load forecasts, the methodology of quantile regression and
error measuring is applied, similar to the approach used in the
previous section. The difference in this approach is that the
combination of individual forecasts is based on the selected
features. Just point forecast models with overlaps of the
selected features are used for generating the final forecast.
The starting point of the testing are the input parameters,
from which the required features are identified to build the
probabilistic model. The system selects the corresponding
point load forecast models based on the selected features
and calculates the individual forecasts. The features and the
forecasts are combined to the probabilistic model. Finally, the
forecast is determined from this [13].
C. Clustering
1) Short Description: In the methodology by Wang [14]
the given data is grouped by using clustering algorithms into
similarity groups. Next, an individual forecast is calculated for
each cluster. The individual results were combined to a form
of probabilistic forecast.
2) Functionality: The model developed in this article can
be considered as a 3 phase model. In the clustering phase, the
individual data points are reduced to common dimensions or
parameters. Subsequently, the data is combined into clusters,
which are selected in such a way that they can be calculated
by suitable forecasting methods.
摘要:

ProbabilisticForecastingMethodsforSystem-LevelElectricityLoadForecastingPhilippGieseTechnischeUniversit¨atBerlinBerlin,GermanyPhilipp.Giese@campus.tu-berlin.deAbstract—Loadforecastshavebecomeanintegralpartofenergysecurity.Duetothevariousinuencingfactorsthatcanbeconsideredinsuchaforecast,thereisalso...

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