Roberto Napoli - Academia.edu (original) (raw)
Publications by Roberto Napoli
International Journal for Academic Development, 2010
... Roberto Di Napoli a *, Heather Fry a,b , Mariane Frenay c , Piet Verhesschen d and AnVerburgh... more ... Roberto Di Napoli a *, Heather Fry a,b , Mariane Frenay c , Piet Verhesschen d and AnVerburgh d ... An Verburgh is currently a doctoral candidate in the Faculty of Psychology and Educational Sciences at the Katholieke Universiteit Leuven. ...
Papers by Roberto Napoli
This report is intended to provide a conceptual framework for assessing the security risk to powe... more This report is intended to provide a conceptual framework for assessing the security risk to power systems assets and operations related to malicious attacks. The problem is analysed with reference to all the actors involved and the possible targets. The specific nature of the malicious attacks is discussed and representations in terms of strategic interaction are proposed. Models based on Game Theory and Multi Agent Systems techniques specifically developed for the representation of malicious attacks against power systems are presented and illustrated with reference to applications to small-scale test systems. The mission of the JRC is to provide customer-driven scientific and technical support for the conception, development, implementation and monitoring of EU policies. As a service of the European Commission, the JRC functions as a reference centre of science and technology for the Union. Close to the policy-making process, it serves the common interest of the Member States, whi...
In spite of the strong believes, the progress and development of smart grids is very slow. The ma... more In spite of the strong believes, the progress and development of smart grids is very slow. The main reasons behind the slow pace are not due to the technical aspects but, perhaps, as a result of an inappropriate business model, not adequately centered to the customers. Nature, with ability to survive and resist, is a splendid example of competitive life. Mathematical models show that natural complex systems are the replication of simple structures. Exploring this approach, smart grids can be seen as an aggregation of mini and micro grids, with the smart user as fundamental stone. The technical aggregation can be paired with a new business model, based on correspondent enterprises, devoted to operation and maintenance. This framework can open new opportunities, favoring innovations, increasing resilience, pushing toward more responsible energy usage behavior while giving tangible economic and social benefits to the customers.
2009 American Control Conference, 2009
In this work a novel nonlinear active noise control (NANC) scheme is proposed to deal with refere... more In this work a novel nonlinear active noise control (NANC) scheme is proposed to deal with reference and error microphone saturation issues. Polynomial NARX models are used in the adaptive controller for enhanced model flexibility. A suitable model selection approach is used off-line to find an accurate and compact model structure for the adaptive controller. The controller parameters are successively updated with an appropriate adaptive algorithm based on the error gradient and on the residual noise. Some simulation experiments are provided to show the effectiveness of the proposed approach compared to existing alternatives.
International Journal of Electrical Power & Energy Systems, 2010
The modeling of the bidding behaviour of the producer is a key-point in the modeling and simulati... more The modeling of the bidding behaviour of the producer is a key-point in the modeling and simulation of the competitive electricity markets. In our paper, the linear supply function model is applied so as to find the Supply Function Equilibrium analytically. It also proposed a new and efficient approach to find SFEs for the network constrained electricity markets by finding
International Journal of Electrical Power & Energy Systems - INT J ELEC POWER ENERG SYST, 1985
A second-order probabilistic load flow technique is presented, which takes into account the effec... more A second-order probabilistic load flow technique is presented, which takes into account the effects of nonlinearities in the system equations and of different dispatching strategies. This approach uses as input a normal probability distribution for the loads. The probability distribution for the generated powers is computed by linearly modelling the dispatching activity. The technique of moments is then applied to second-order approximations for the load flow and current equations, allowing the noniterative computation of the means and standard deviations for the various output quantities. Generation outages are separately treated, with the possibility of embedding different postoutage dispatching strategies. The cumulative results are finally obtained by combining the pertinent probabilistic load flows with the occurrence probabilities of the various conditions. Results on two sample systems are given.
International Journal of Hydrogen Energy, 2008
Solid oxide fuel cell (SOFC) has an electrolyte that is solid and works at a temperature range of... more Solid oxide fuel cell (SOFC) has an electrolyte that is solid and works at a temperature range of 60021000 C; it can use a wide range of fuels and the relatively high operating temperature makes it possible for internal reforming with high-quality heat by-product for cogeneration. In this paper, we address quantitatively the problem with reference to a 5 kW SOFC power system for residential use. The goal of the paper is to provide an analysis of possible scenarios that will make SOFC applications feasible from an economic point of view. In this respect we provide a sensitivity analysis of some common financial metrics to key input parameters, the improvements in electrical efficiency, changes in regulatory policy and changes in the market energy prices. The economic feasibility of different scenarios is evaluated and compared resorting to the usual metrics in financial analysis.
Electric Power Systems Research, 2006
The physical and operational constraints of the network pose very specific problems to market pow... more The physical and operational constraints of the network pose very specific problems to market power analysis in the oligopolistic electricity markets. This paper presents a direct analytical approach to find the market equilibrium based on a supply function game model. The model is exploited to undertake a sensitivity analysis of the producer surplus with reference to the line flow limits under a DC power flow model for network representation. Two different kinds of indices, that can capture the market power arising under network constraints, are proposed. The first set of indices is the location privilege (LP), that measure the effect of the generators positioning in the grid on their surplus under perfect competition. The second set is for the network market power (NMP) indices that take into account the strategic behaviors of the producers that may take advantage of the congestion of the transmission lines. The indices allow for a ranking of the lines in terms of the market power they can induce and, in this respect, they may help the market regulator to focus on the network weakness in terms of the possible market outcomes under the market power behaviors from the supply side. The application of the proposed indices is illustrated with reference to the IEEE 30-bus test system.
Critical Information Infrastructures Security, 2008
Power grids have been widely acknowledged as complex networks (CN) since this theory emerged and ... more Power grids have been widely acknowledged as complex networks (CN) since this theory emerged and received considerable attention recently. Many works have been performed to investigate the structural vulnerability of power grids from the topological point of view based on CN. However, most of them applied conceptions and measurements of CN directly to the analysis of power grids which have
This paper reviews concepts and methods for electricity customers classification in competitive e... more This paper reviews concepts and methods for electricity customers classification in competitive electricity markets. We present an overview of classification techniques, including classical approaches (applications of statistics and deterministic clustering techniques), as well as methods based on artificial intelligence (neural networks, fuzzy systems) and frequency domain approaches (harmonic analysis and wavelets). We focus on methods developed to highlight the electrical behaviour of customers. We illustrate the classification techniques by using a set of features characterising the shape of the load diagrams. We recall and discuss some metrics available to quantify the classification adequacy and add an original one. The issues discussed are detailed with real-case examples. Index Terms – Electricity markets, Load diagrams, Customer Classification, Clustering, Neural Networks, Self Organising Maps.
Global earthing systems (GESs), created by the interconnection of local earthing systems, should ... more Global earthing systems (GESs), created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. One of the reasons for this safety characteristic of GESs is the fault current distribution between grounding electrodes and medium-voltage (MV) cable sheaths: Only a small portion of the fault current is injected into the ground by the ground grid of the faulty substation. In systems with isolated neutral or with resonant earthing, this effect may be sufficient to provide safety from electric shock. In this paper, a model describing the behavior of the MV distribution system with interconnected grounding electrodes during a ground fault is built. It is then used to analyze the impact of different factors on the fault current distribution. A sensitivity analysis is performed, varying the main parameters, and the results are used to draw some conclusions on the current distribution influence on GESs.
The authors propose a new approach for solving the nonlinear problem, based on a model-reference ... more The authors propose a new approach for solving the nonlinear problem, based on a model-reference adaptive control (MRAC). The algorithm is composed of three parts: a plant containing unknown parameters, a reference model for compactly specifying the desired output and an adaptation mechanism for updating the adjustable parameters. The structure of the adaptation mechanism is explicitly designed so that the asymptotical stability is guaranteed according to Lyapunov theorem. The method reformulates the algebraic nonlinear equations into a set of ordinary differential equations, whose equilibrium point corresponds to the solution of the original nonlinear problems. The stability and region of attraction coincide with entire state space no matter whether the parameters reside in solvable region or unsolvable region.
This paper deals with grouping electricity customers on the basis of their electrical behavior. W... more This paper deals with grouping electricity customers on the basis of their electrical behavior. We refer to a set of daily load diagrams representing a macro-class of electricity customers defined on the basis of external classification criteria. We investigate on the selection of appropriate features to be used for grouping the customers by means of clustering techniques. We propose a novel characterization of the load diagrams by using a frequency-domain approach in which each customer is represented by a set of harmonics-based features. Assuming the day as fundamental period, we perform harmonic analysis of the representative load diagrams and define a set of shape factors by using magnitude and phase information of a relevant set of harmonics. We discuss some critical aspects of the feature selection, mainly linked to the treatment of the phase information. We show results of application of the proposed method to 232 customers of a real distribution system. Using the proposed ha...
Global earthing systems (GESs), which are created by the interconnection of local earthing system... more Global earthing systems (GESs), which are created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. According to international standards, one of the reasons for this safety characteristic of GESs is that medium-voltage and low-voltage grounding systems form a quasi-equipotential area. Typical examples of GESs are in city centers due to the high number of interconnected grounding systems in the area. For this reason, in addition to ground grids, other metallic parts with different primary functions shall be also considered, e.g., water and gas pipes, tramway tracks, and building foundations can modify the electric potential distribution in the area. In this paper, a model based on the Maxwell's subareas method (MaSM) is used to evaluate how buried metallic parts, which are not intentionally connected to ground grids, modify the electric potential on the soil surface. First, the MaSM model is validated with experimental mea...
The present trend towards extended adoption of energy production from renewable sources is leadin... more The present trend towards extended adoption of energy production from renewable sources is leading to increased attention towards the diffusion of grid-connected photovoltaic (PV) systems. Different technologies are available for the connection of the PV systems to the grid through inverter-based Power Conditioning Units (PCUs). This paper presents the results of a comparative study referred to the characteristics of different types of PCUs, based on the experimental results obtained for a wide range of solar irradiance and operating conditions. The performance of the grid connection has been characterised by using a set of parameters, referred both to the DC and to the AC side of the inverter, such as the efficiency of the maximum power point tracking, the DC/AC efficiency, the power factor and the harmonic distortion of voltage and current at the interface with the grid. The PV systems have been further characterised by considering their ability of avoiding the undesired islanding...
International Journal for Academic Development, 2010
... Roberto Di Napoli a *, Heather Fry a,b , Mariane Frenay c , Piet Verhesschen d and AnVerburgh... more ... Roberto Di Napoli a *, Heather Fry a,b , Mariane Frenay c , Piet Verhesschen d and AnVerburgh d ... An Verburgh is currently a doctoral candidate in the Faculty of Psychology and Educational Sciences at the Katholieke Universiteit Leuven. ...
This report is intended to provide a conceptual framework for assessing the security risk to powe... more This report is intended to provide a conceptual framework for assessing the security risk to power systems assets and operations related to malicious attacks. The problem is analysed with reference to all the actors involved and the possible targets. The specific nature of the malicious attacks is discussed and representations in terms of strategic interaction are proposed. Models based on Game Theory and Multi Agent Systems techniques specifically developed for the representation of malicious attacks against power systems are presented and illustrated with reference to applications to small-scale test systems. The mission of the JRC is to provide customer-driven scientific and technical support for the conception, development, implementation and monitoring of EU policies. As a service of the European Commission, the JRC functions as a reference centre of science and technology for the Union. Close to the policy-making process, it serves the common interest of the Member States, whi...
In spite of the strong believes, the progress and development of smart grids is very slow. The ma... more In spite of the strong believes, the progress and development of smart grids is very slow. The main reasons behind the slow pace are not due to the technical aspects but, perhaps, as a result of an inappropriate business model, not adequately centered to the customers. Nature, with ability to survive and resist, is a splendid example of competitive life. Mathematical models show that natural complex systems are the replication of simple structures. Exploring this approach, smart grids can be seen as an aggregation of mini and micro grids, with the smart user as fundamental stone. The technical aggregation can be paired with a new business model, based on correspondent enterprises, devoted to operation and maintenance. This framework can open new opportunities, favoring innovations, increasing resilience, pushing toward more responsible energy usage behavior while giving tangible economic and social benefits to the customers.
2009 American Control Conference, 2009
In this work a novel nonlinear active noise control (NANC) scheme is proposed to deal with refere... more In this work a novel nonlinear active noise control (NANC) scheme is proposed to deal with reference and error microphone saturation issues. Polynomial NARX models are used in the adaptive controller for enhanced model flexibility. A suitable model selection approach is used off-line to find an accurate and compact model structure for the adaptive controller. The controller parameters are successively updated with an appropriate adaptive algorithm based on the error gradient and on the residual noise. Some simulation experiments are provided to show the effectiveness of the proposed approach compared to existing alternatives.
International Journal of Electrical Power & Energy Systems, 2010
The modeling of the bidding behaviour of the producer is a key-point in the modeling and simulati... more The modeling of the bidding behaviour of the producer is a key-point in the modeling and simulation of the competitive electricity markets. In our paper, the linear supply function model is applied so as to find the Supply Function Equilibrium analytically. It also proposed a new and efficient approach to find SFEs for the network constrained electricity markets by finding
International Journal of Electrical Power & Energy Systems - INT J ELEC POWER ENERG SYST, 1985
A second-order probabilistic load flow technique is presented, which takes into account the effec... more A second-order probabilistic load flow technique is presented, which takes into account the effects of nonlinearities in the system equations and of different dispatching strategies. This approach uses as input a normal probability distribution for the loads. The probability distribution for the generated powers is computed by linearly modelling the dispatching activity. The technique of moments is then applied to second-order approximations for the load flow and current equations, allowing the noniterative computation of the means and standard deviations for the various output quantities. Generation outages are separately treated, with the possibility of embedding different postoutage dispatching strategies. The cumulative results are finally obtained by combining the pertinent probabilistic load flows with the occurrence probabilities of the various conditions. Results on two sample systems are given.
International Journal of Hydrogen Energy, 2008
Solid oxide fuel cell (SOFC) has an electrolyte that is solid and works at a temperature range of... more Solid oxide fuel cell (SOFC) has an electrolyte that is solid and works at a temperature range of 60021000 C; it can use a wide range of fuels and the relatively high operating temperature makes it possible for internal reforming with high-quality heat by-product for cogeneration. In this paper, we address quantitatively the problem with reference to a 5 kW SOFC power system for residential use. The goal of the paper is to provide an analysis of possible scenarios that will make SOFC applications feasible from an economic point of view. In this respect we provide a sensitivity analysis of some common financial metrics to key input parameters, the improvements in electrical efficiency, changes in regulatory policy and changes in the market energy prices. The economic feasibility of different scenarios is evaluated and compared resorting to the usual metrics in financial analysis.
Electric Power Systems Research, 2006
The physical and operational constraints of the network pose very specific problems to market pow... more The physical and operational constraints of the network pose very specific problems to market power analysis in the oligopolistic electricity markets. This paper presents a direct analytical approach to find the market equilibrium based on a supply function game model. The model is exploited to undertake a sensitivity analysis of the producer surplus with reference to the line flow limits under a DC power flow model for network representation. Two different kinds of indices, that can capture the market power arising under network constraints, are proposed. The first set of indices is the location privilege (LP), that measure the effect of the generators positioning in the grid on their surplus under perfect competition. The second set is for the network market power (NMP) indices that take into account the strategic behaviors of the producers that may take advantage of the congestion of the transmission lines. The indices allow for a ranking of the lines in terms of the market power they can induce and, in this respect, they may help the market regulator to focus on the network weakness in terms of the possible market outcomes under the market power behaviors from the supply side. The application of the proposed indices is illustrated with reference to the IEEE 30-bus test system.
Critical Information Infrastructures Security, 2008
Power grids have been widely acknowledged as complex networks (CN) since this theory emerged and ... more Power grids have been widely acknowledged as complex networks (CN) since this theory emerged and received considerable attention recently. Many works have been performed to investigate the structural vulnerability of power grids from the topological point of view based on CN. However, most of them applied conceptions and measurements of CN directly to the analysis of power grids which have
This paper reviews concepts and methods for electricity customers classification in competitive e... more This paper reviews concepts and methods for electricity customers classification in competitive electricity markets. We present an overview of classification techniques, including classical approaches (applications of statistics and deterministic clustering techniques), as well as methods based on artificial intelligence (neural networks, fuzzy systems) and frequency domain approaches (harmonic analysis and wavelets). We focus on methods developed to highlight the electrical behaviour of customers. We illustrate the classification techniques by using a set of features characterising the shape of the load diagrams. We recall and discuss some metrics available to quantify the classification adequacy and add an original one. The issues discussed are detailed with real-case examples. Index Terms – Electricity markets, Load diagrams, Customer Classification, Clustering, Neural Networks, Self Organising Maps.
Global earthing systems (GESs), created by the interconnection of local earthing systems, should ... more Global earthing systems (GESs), created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. One of the reasons for this safety characteristic of GESs is the fault current distribution between grounding electrodes and medium-voltage (MV) cable sheaths: Only a small portion of the fault current is injected into the ground by the ground grid of the faulty substation. In systems with isolated neutral or with resonant earthing, this effect may be sufficient to provide safety from electric shock. In this paper, a model describing the behavior of the MV distribution system with interconnected grounding electrodes during a ground fault is built. It is then used to analyze the impact of different factors on the fault current distribution. A sensitivity analysis is performed, varying the main parameters, and the results are used to draw some conclusions on the current distribution influence on GESs.
The authors propose a new approach for solving the nonlinear problem, based on a model-reference ... more The authors propose a new approach for solving the nonlinear problem, based on a model-reference adaptive control (MRAC). The algorithm is composed of three parts: a plant containing unknown parameters, a reference model for compactly specifying the desired output and an adaptation mechanism for updating the adjustable parameters. The structure of the adaptation mechanism is explicitly designed so that the asymptotical stability is guaranteed according to Lyapunov theorem. The method reformulates the algebraic nonlinear equations into a set of ordinary differential equations, whose equilibrium point corresponds to the solution of the original nonlinear problems. The stability and region of attraction coincide with entire state space no matter whether the parameters reside in solvable region or unsolvable region.
This paper deals with grouping electricity customers on the basis of their electrical behavior. W... more This paper deals with grouping electricity customers on the basis of their electrical behavior. We refer to a set of daily load diagrams representing a macro-class of electricity customers defined on the basis of external classification criteria. We investigate on the selection of appropriate features to be used for grouping the customers by means of clustering techniques. We propose a novel characterization of the load diagrams by using a frequency-domain approach in which each customer is represented by a set of harmonics-based features. Assuming the day as fundamental period, we perform harmonic analysis of the representative load diagrams and define a set of shape factors by using magnitude and phase information of a relevant set of harmonics. We discuss some critical aspects of the feature selection, mainly linked to the treatment of the phase information. We show results of application of the proposed method to 232 customers of a real distribution system. Using the proposed ha...
Global earthing systems (GESs), which are created by the interconnection of local earthing system... more Global earthing systems (GESs), which are created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. According to international standards, one of the reasons for this safety characteristic of GESs is that medium-voltage and low-voltage grounding systems form a quasi-equipotential area. Typical examples of GESs are in city centers due to the high number of interconnected grounding systems in the area. For this reason, in addition to ground grids, other metallic parts with different primary functions shall be also considered, e.g., water and gas pipes, tramway tracks, and building foundations can modify the electric potential distribution in the area. In this paper, a model based on the Maxwell's subareas method (MaSM) is used to evaluate how buried metallic parts, which are not intentionally connected to ground grids, modify the electric potential on the soil surface. First, the MaSM model is validated with experimental mea...
The present trend towards extended adoption of energy production from renewable sources is leadin... more The present trend towards extended adoption of energy production from renewable sources is leading to increased attention towards the diffusion of grid-connected photovoltaic (PV) systems. Different technologies are available for the connection of the PV systems to the grid through inverter-based Power Conditioning Units (PCUs). This paper presents the results of a comparative study referred to the characteristics of different types of PCUs, based on the experimental results obtained for a wide range of solar irradiance and operating conditions. The performance of the grid connection has been characterised by using a set of parameters, referred both to the DC and to the AC side of the inverter, such as the efficiency of the maximum power point tracking, the DC/AC efficiency, the power factor and the harmonic distortion of voltage and current at the interface with the grid. The PV systems have been further characterised by considering their ability of avoiding the undesired islanding...