Quim Melendez

Universitat de Girona, Institut d'Informatica i Aplicacions, Faculty Member

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Papers by Quim Melendez

Electrical consumption of one building located at the Campus of University of Girona

This dataset is a supplement of the the following paper "Identifying services for short-term... more This dataset is a supplement of the the following paper "Identifying services for short-term load forecasting using data driven models in a Smart City platform". Authors: J. Massana, C. Pous et al.Journal: Sustainable Cities and Society, Vol. 28, Jan. 2017, pp. 108-117. https://doi.org/10.1016/j.scs.2016.09.001 Each excel file contains the electrical consumption of one building located at the Campus of University of Girona. Data were collected from 2011 to 2014. Column information for the excel files: Hora: hour of the day (0, 1... 23). Dia: day of the month (1, 2... 31). Dia_set: day of the week (1,2... 7). Mes: month (1,2... 12) Any: year (2011... 2014). C: electrical consumption (kWh)

Supervised Fuzzy Control of Dissolved Oxygen in a SBR Pilot Plant

Conference on Artificial Intelligence Research and Development, May 12, 2005

This work is focused on controlling the Dissolved Oxygen in a SBR pilot plant fed with real waste... more This work is focused on controlling the Dissolved Oxygen in a SBR pilot plant fed with real wastewater. Two different implementations of Dissolved Oxygen control are presented. On the one hand, an ON/OFF control produces oscillations around the set point, this cycling behavior affects other process variables and makes the supervisory tasks more difficult. On the other hand fuzzy control allows a better Dissolved Oxygen behavior, which means a global process behavior. The results of using both methods are shown and compared.

Monitoring of low voltage grids with multilayer principal component analysis

International Journal of Electrical Power & Energy Systems, Feb 1, 2021

This article presents a monitoring strategy based on multilayer principal component analysis (PCA... more This article presents a monitoring strategy based on multilayer principal component analysis (PCA) to detect and diagnose power system disturbances in large amounts of data collected by intelligent electronic devices in low voltage smart grids. The PCA models are built on multiple sliding windows, sized (in terms of length and sampling time) according to the type of phenomena to detect. Abnormalities are detected with use of two complementary statistical indexes, then diagnosed by computing the individual contributions of each monitored variable to the constraint violation of those statistics. As a result, its implementation enables an automatic analysis of multiple phenomena of interest in parallel over time using distinct electrical quantities. Furthermore, the method is demonstrated within the RESOLVD project with data from the OpenLV project containing measurements of active and reactive power gathered at different low voltage distribution substations.

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FUTURA: Hybrid System for Electric Load Forecasting by Using Case-Based Reasoning and Expert System

Springer eBooks, 2002

The results of combining a numeric extrapolation of data with the methodology of case-based reaso... more The results of combining a numeric extrapolation of data with the methodology of case-based reasoning and expert systems in order to improve the electric load forecasting are presented in this contribution. Registers of power consumption are stored as cases that are retrieved and adapted by an expert system to improve a numeric forecasting given by numeric algorithms. FUTURA software has been developed as a result of this work. It combines the proposed techniques in a modular way while it provides a graphic user interface and access capabilities to existing data bases.

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Medical Equipment Maintenance Support with Service-Oriented Multi-agent Services

Springer eBooks, 2012

Service oriented architectures (SOA) have emerged as an approach to handle the complexity of ente... more Service oriented architectures (SOA) have emerged as an approach to handle the complexity of enterprise interoperability. Recently, multi-agent systems have been promoted as a technique to deal with cooperation issues involved in SOA. This cooperation is particularly important in several application domains, in which different companies are involved in a concrete service deployment. Agents, among other issues, offer the possibility to decide, if more than one option is available, providing flexibility and robustness. In this paper, we describe the agent-based cooperation process we have followed to enable partner's cooperation in an equipment maintenance workflow. The use of ontologies and relationships with standards is highlighted. The approach is illustrated in an hospital scenario considered in the AIMES project.

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Case Base Management for Analog Circuits Diagnosis Improvement

Springer eBooks, 2003

There have been some Artificial Intelligence applications developed for electronic circuits diagn... more There have been some Artificial Intelligence applications developed for electronic circuits diagnosis, but much remains to be done in this field, above all in the analog domain. The purpose of this paper is not to give a general solution, but to contribute with a new methodology. Our aim is to develop a methodology for analog circuit diagnosis based on improving the well-known fault dictionary techniques by means of new cases addition or adaptation towards a Case Based Reasoning system. As an example, a fault dictionary method have been studied in detail. It has been used as starting point for case base construction to be applied to a real electronic circuit. The faults considered are parametric, permanent, independent and simple.

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Opportunities and challenges for smart power restoration and reconfiguration smart decisions with smart grids

... Youssef Oualmakran, Joaquim Meléndez, Sergio Herraiz eXit Group, Department of Informatics an... more

Extending a Fault Dictionary Towards a Case Based Reasoning System for Linear Electronic Analog Circuits Diagnosis

Lecture Notes in Computer Science, 2004

There are plenty of methods proposed for analog electronic circuit diagnosis, but the most popula... more There are plenty of methods proposed for analog electronic circuit diagnosis, but the most popular ones are the fault dictionary techniques. Admitting more cases in a fault dictionary can be seen as a natural development towards a CBR system. The proposal of this paper is to extend the fault dictionary towards a Case Based Reasoning system. The case base memory, retrieval, reuse, revise and retain tasks are described. Special attention to the learning process is taken. An application example on a biquadratic filter is shown. The faults considered are parametric, permanent, independent and simple, although the methodology could be extrapolated for catastrophic and multiple fault diagnosis. Also, the method is focused and tested only on passive faulty components. Nevertheless, it can be extended to cover active devices as well.

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eXiT Research Group at the University of Girona: Artificial intelligence and machine learning applied to medicine and healthcare

This paper describes the research activity of the eXiT research group at the Universitat of Giron... more This paper describes the research activity of the eXiT research group at the Universitat of Girona and the main results achieved. The research is organized in four main groups: prognosis, clinical decision support systems, mHealth, and biosignal processing. The paper describes past, current and future research of the group.

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Dealing with Qualitative Information for Supervisory Systems Design in Cassd Frameworks

IFAC Proceedings Volumes, May 1, 1997

Analysis of measured process data and extraction of process trends are essential for reasoning ab... more Analysis of measured process data and extraction of process trends are essential for reasoning about the process behaviour. In this paper a symbolic representation of signals is presented, this representation is based on a segmentation of signals in episodes depending on their convexity, and a classification ofthese episodes. In order to apply these techniques in continuous systems supervision, fuzzy reasoning is introduced and Simulink is used as implementation tool, allowing its integration in a CASSD framework.

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FIR Differentiator Based on a Polynomial Least Squares Estimation. Application to PID Control

IFAC Proceedings Volumes, Apr 1, 2000

This paper presents a new method for getting a discrete differentiator that approximates ideal de... more This paper presents a new method for getting a discrete differentiator that approximates ideal derivative in the range low frequency components and eliminates the noise amplification for high frequency components of input signal. The proposal is based on the estimation of the derivative in a time-windowed signal by means of the slope of a first order polynomial. The estimation is obtained by using least squares algorithm. The paper is focused in obtaining a finite impulse response (FIR) differentiator filter for this purpose. The method for obtaining the filter coefficients is demonstrated and the benefits of using this approach in presence of noise in PID control are presented.

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Principal Component Analysis for Monitoring Electrical Consumption of Academic Buildings

Energy Procedia, 2014

In this paper Principal Component Analysis (PCA) is proposed for monitoring electric consumption ... more In this paper Principal Component Analysis (PCA) is proposed for monitoring electric consumption of building. PCA allows modeling correlations between independent variables (weather, calendar) and energy consumption at different time scales (hourly, daily, weekly monthly). Multiway principal component analysis (MPCA) is used to model time dependencies of variables as it is commonly done in batch process monitoring. This approach allows defining simple statistic indices T 2 and SPE to be used in monitoring charts. These indices are used to detect abnormal behaviours at selected time scales. After detection, contribution analysis is performed to isolate variables responsible of such misbehaviour. Exploitation of such models, obtained during normal operating conditions, can be used to detect both faults in sensors and misbehaviours in consumption patterns with respect to independent variables. The paper presents the methodology and illustrates it in a case study focused on academic buildings situated in the Campus of the University of Girona.

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Assessment of electric vehicle charging hub based on stochastic models of user profiles

Expert Systems With Applications, Oct 1, 2023

Potential benefits of scheduling electric vehicle sessions over limiting charging power

CIRED Porto Workshop 2022: E-mobility and power distribution systems, 2022

This work addresses the management of charging infrastructure to cope with the problem of congest... more This work addresses the management of charging infrastructure to cope with the problem of congestion in the electric grid by exploiting electric vehicle (EV) flexibility. Benefits of scheduling charging sessions based on user profiles is compared with two traditional methods for limiting charging power: using static a dynamic control signal. The user profile concept is a classification strategy that consists in assigning a label to every EV user, referring to a connection pattern in the daily use of the charging infrastructure. The study analyses pros and cons of these three approaches and highlight the advantages of demand-response programs based on the user profiles. Thus, while limiting the power of charging sessions with a static signal causes a rebound effect, using a dynamic signal requires impacting a high amount of sessions. Scheduling (i.e. postponing) the charging sessions associated to profiles with low-variance provides a higher efficiency of the demand-response program since the same objective (i.e. peak demand reduction to 350 kW) is achieved with a lower number of participating sessions (40% fewer than limiting charging power with dynamic signal).

format_quotePilot projects like Flexpower in Amsterdam showed successful implementation of static signal limiting EV charging power, enhancing grid stability.format_quote

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Case based reasoning methodology for supervision

The methodology of case base reasoning (CBR) is proposed to perform supervisory tasks in industri... more The methodology of case base reasoning (CBR) is proposed to perform supervisory tasks in industrial process. An outlook of main difficulties in applying this methodology in dynamic systems is contrasted with the benefits of applying it. A generic case definition is proposed to achieve supervisory tasks in the domain of dynamic systems. This methodology has been implemented for improving the control of a batch drier chamber. A discussion related to monitoring a discrete events laboratory plant is also discussed. It includes the definition of similarity functions according to time evolution for case retrieving and its use for diagnosis and fault detection.

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An application of geographic information system to three-phase distribution power flow

ABSTRACT In this paper, the integration of the GIS database and application software is illustrat... more ABSTRACT In this paper, the integration of the GIS database and application software is illustrated by using a three-phase distribution power flow. The database can be used for inventory, facility management engineering analysis and map productions. Facility data or network model can be retrieved from the data base. The work describes a complete modeling of elements in a distribution system. The paper report: lines, transformer, load and shunt Var elements. The system configuration can be any combination of single, two and three phase circuits The effects of neutral and ground return paths are include. Transformer losses (core and leakage) and lines losses can be clearly identified in a quantitative manner. This paper will discuss a method to simulate the system in a rigorous way, because a typical feeder involves three-phase, two phase and single phase lateral lines. Finally we report the use of this system in Peru for the study of the Valor Agregado de Distribution (VAD)-yard stick competition - in order to obtain the electric rates in Peru for the next 4 years. The load forecasting is obtained from a hybrid system of case based reasoning and expert systems.

Flexibility management of electric vehicles based on user profiles: The Arnhem case study

International Journal of Electrical Power & Energy Systems, Dec 1, 2021

The ever-increasing global adoption of electric vehicles has created both challenges and opportun... more The ever-increasing global adoption of electric vehicles has created both challenges and opportunities for electrical grids and power systems as well as the market itself. Smart charging is broadly presented as a relevant opportunity to provide demand-side flexibility, benefiting both the user and the power system through flexibility aggregators. However, coordinating all sessions for the same optimization objective could be inefficient when the flexibility potential mismatches the flexibility demand. Instead, this paper proposes the user profile concept as a tool to group sessions into similar flexibility levels and then schedule the charging sessions of each user profile according to its most convenient optimization objective. Therefore, a clustering methodology based on a bivariate Gaussian Mixture Models is presented and validated with a real-world data set, resulting in seven different user profiles. The simulation of two smart charging scenarios, first coordinating all flexible sessions and second coordinating two selected user profiles, resulted in a more efficient scheduling in the latter case, obtaining similar results with a 35% fewer sessions shifted and the corresponding reduction in exploitation costs.

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Expert supervision based on cases

The paper focuses on taking advantage of large amounts of data that are systematically stored in ... more The paper focuses on taking advantage of large amounts of data that are systematically stored in plants (by means of SCADA systems), but not exploited enough in order to achieve supervisory goals (fault detection, diagnosis and reconfiguration). The methodology of case base reasoning (CBR) is proposed to perform supervisory tasks in industrial processes by re-using the stored data. The goal is to take advantage of experiences, registered in a suitable structure as cam, avoiding the tedious task of knowledge acquisition and representation needed by other reasoning techniques as expert systems. An outlook of CBR terminology and basic concepts are presented. The adaptation of CBR in performing expert supervisory tasks, taking into account the particularities and difficulties derived from dynamic systems, is discussed. A special interest is focused in proposing a general case definition suitable for supervisory tasks. Finally, this structure and the whole methodology is tested in a application example for monitoring a real drier chamber

Proceedings of the 2006 conference on Artificial Intelligence Research and Development

Sistemas De Acoplamiento De Rigidez Variable en Plantas Industriales Con Generacion Distribuida

Dyna, 2017

A lot of industrial facilities with Cogeneration Heat and Power (CHP) exists working electrically... more A lot of industrial facilities with Cogeneration Heat and Power (CHP) exists working electrically as Distributed Generation (DG). In these utilities the cogeneration unit operate in parallel with the network, but several times due to electrical disturbances, islanding operation mode is chosen. This mode is activated when disturbances appeared or are expected to appear in the network. During islanding mode both facilities and receivers are affected by the low electrical stability of the own generation. Stability disturbances are mainly referred both frecuency and voltaje stability. Disturbances also appears in the moment of the reconnection from islanding to normal operation mode. In order to avoid these inconvenients between rigid network connection and islanding operation mode an alternative solution is approached in this document, is the so-called Adaptative Rigid System( ARS). Through this system we can electrically move far away enough from network to disturbances do not affect the operation of our Plant. On the other hand, we can keep the electrical stability provided by the external network. To conclude we will describe the advantages on this (ARS) system against normal operation modes.

format_quoteDecreasing coupling rigidity improves immunity to disturbances but reduces energy evacuation capacity and modifies fault current.format_quote

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Quim Melendez

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