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Publications

Publications by CPES

2017

A Scalable Load Forecasting System for Low Voltage Grids

Authors
Reis, M; Garcia, A; Bessa, RJ;

Publication
2017 IEEE MANCHESTER POWERTECH

Abstract
A recent research trend is driven to increase the monitoring and control capabilities of low voltage networks. This paper describes a probabilistic forecasting methodology based on kernel density estimation and that makes use of distributed computing techniques to create a highly scalable forecasting system for LV networks. The results show that the proposed algorithm outperforms three benchmark models (one for point forecast and two for probabilistic forecasts) and demonstrate the applicability of the distributed in-memory computing solution for a practical operational scenario. The ultimate goal is to integrate information about net-load forecasts in power flow optimization frameworks for low voltage networks in order to solve technical constraints with the available home energy management system flexibility.

2017

Towards Improved Understanding of the Applicability of Uncertainty Forecasts in the Electric Power Industry

Authors
Bessa, RJ; Mohlen, C; Fundel, V; Siefert, M; Browell, J; El Gaidi, SH; Hodge, BM; Cali, U; Kariniotakis, G;

Publication
ENERGIES

Abstract
Around the world wind energy is starting to become a major energy provider in electricity markets, as well as participating in ancillary services markets to help maintain grid stability. The reliability of system operations and smooth integration of wind energy into electricity markets has been strongly supported by years of improvement in weather and wind power forecasting systems. Deterministic forecasts are still predominant in utility practice although truly optimal decisions and risk hedging are only possible with the adoption of uncertainty forecasts. One of the main barriers for the industrial adoption of uncertainty forecasts is the lack of understanding of its information content (e.g., its physical and statistical modeling) and standardization of uncertainty forecast products, which frequently leads to mistrust towards uncertainty forecasts and their applicability in practice. This paper aims at improving this understanding by establishing a common terminology and reviewing the methods to determine, estimate, and communicate the uncertainty in weather and wind power forecasts. This conceptual analysis of the state of the art highlights that: (i) end-users should start to look at the forecast's properties in order to map different uncertainty representations to specific wind energy-related user requirements; (ii) a multidisciplinary team is required to foster the integration of stochastic methods in the industry sector. A set of recommendations for standardization and improved training of operators are provided along with examples of best practices.

2017

Predictive management of low-voltage grids

Authors
Reis, M; Garcia, A; Bessa, R; Seca, L; Gouveia, C; Moreira, J; Nunes, P; Matos, PG; Carvalho, F; Carvalho, P;

Publication
CIRED - Open Access Proceedings Journal

Abstract

2017

Towards new data management platforms for a DSO as market enabler - UPGRID Portugal demo

Authors
Alonso, A; Couto, R; Pacheco, H; Bessa, R; Gouveia, C; Seca, L; Moreira, J; Nunes, P; Matos, PG; Oliveira, A;

Publication
CIRED - Open Access Proceedings Journal

Abstract
In the framework of the Horizon 2020 project UPGRID, the Portuguese demo is focused on promoting the exchange of smart metering data between the DSO and different stakeholders, guaranteeing neutrality, efficiency and transparency. The platform described in this study, named the Market Hub Platform, has two main objectives: (i) to guarantee neutral data access to all market agents and (ii) to operate as a market hub for the home energy management systems flexibility, in terms of consumption shift under dynamic retailing tariffs and contracted power limitation requests in response to technical problems. The validation results are presented and discussed in terms of scalability, availability and reliability.

2017

Probabilistic Price Forecasting for Day-Ahead and Intraday Markets: Beyond the Statistical Model

Authors
Andrade, JR; Filipe, J; Reis, M; Bessa, RJ;

Publication
SUSTAINABILITY

Abstract
Forecasting the hourly spot price of day-ahead and intraday markets is particularly challenging in electric power systems characterized by high installed capacity of renewable energy technologies. In particular, periods with low and high price levels are difficult to predict due to a limited number of representative cases in the historical dataset, which leads to forecast bias problems and wide forecast intervals. Moreover, these markets also require the inclusion of multiple explanatory variables, which increases the complexity of the model without guaranteeing a forecasting skill improvement. This paper explores information from daily futures contract trading and forecast of the daily average spot price to correct point and probabilistic forecasting bias. It also shows that an adequate choice of explanatory variables and use of simple models like linear quantile regression can lead to highly accurate spot price point and probabilistic forecasts. In terms of point forecast, the mean absolute error was 3.03 Euro/MWh for day-ahead market and a maximum value of 2.53 Euro/MWh was obtained for intraday session 6. The probabilistic forecast results show sharp forecast intervals and deviations from perfect calibration below 7% for all market sessions.

2017

Solar power forecasting with sparse vector autoregression structures

Authors
Cavalcante, L; Bessa, RJ;

Publication
2017 IEEE MANCHESTER POWERTECH

Abstract
The strong growth that is felt at the level of photovoltaic (PV) power generation craves for more sophisticated and accurate forecasting methods that could be able to support its proper integration into the energy distribution network. Through the combination of the vector autoregression model (VAR) with the least absolute shrinkage and selection operator (LASSO) framework, a set of sparse VAR structures can be obtained in order to capture the dynamic of the underlying system. The robust and efficient alternating direction method of multipliers (ADMM), well known for its great ability dealing with high-dimensional data (scalability and fast convergence), is applied to fit the resulting LASSO-VAR variants. This spatial-temporal forecasting methodology has been tested, using 1-hour and 15-minutes resolution, for 44 microgeneration units time-series located in a city in Portugal. A comparison with the conventional autoregressive (AR) model is performed leading to an improvement up to 11%.

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