Search

Nowadays, the attainment of flexibility in different loads for different electricity customers is an interesting topic. The assessment of flexibility is important because of the ultimate benefits t...

Contrary to many expectations, the development of smart (mini-)grids is slow, notwithstanding drastic improvements in innovative technologies, and the reasons for this are not strictly technical. The problem lies in regulatory barriers. Moreover, the current business models accommodate utilities more so than customers. Net metering is a key enabling factor for smart (mini-)grids. This article addresses the economic benefits of net metering for residential customers. Energy demands for individual apartments and common areas are calculated using the daily energy-consumption behavior of occupants for typical days of each month of the year. Photovoltaic (PV ) generation is estimated for a residential building in Italy. The proposed net-metering scheme is applied on the aggregate energy demand of a selected building. The current energy billing without modifications is compared to the case in which net-metering tariffs are applied to the billing. Results show that noticeable savings can be obtained in the net-metering case.

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 measurements on a simple electrode configuration. The measured voltages are compared with the MaSM results and with the results obtained with a finite-element method model simulated with COMSOL Multiphysics. Then, the simulations are carried out on a realistic urban test case.

International Standards define a Global Earthing System as an earthing net created interconnecting local Earthing Systems (generally through the shield of MV cables and/or bare buried conductors). In Italy, the regulatory authority for electricity and gas requires distributors to guarantee the electrical continuity of LV neutral conductor. This requirement has led to the standard practice of realizing “reinforcement groundings” along the LV neutral conductor path and at users’ delivery cabinet. Moreover, in urban high-load scenarios (prime candidates to be part of a Global Earthing System), it is common that LV distribution scheme creates, through neutral conductors, an effective connection between grounding systems of MV/LV substations, modifying Global Earthing System consistency. The aim of this paper is to evaluate the effect, in terms of electrical safety, of the aforementioned LV neutral distribution scheme when an MV-side fault to ground occurs. For this purpose, simulations are carried out on a realistic urban test case and suitable evaluation indexes are proposed.

In spite of the strong believes, the progress and maturity in the deployment 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.

Nowadays, enhanced knowledge of the nature of the electricity demand is achieved through the progressively increasing deployment of smart meters and advanced data analysis techniques. One of the major challenges is to exploit this knowledge to support the introduction of strategies to modify the demand according to relevant objectives to be achieved, like users’ participation in demand response programmes. A key point for facing this challenge is to characterize the demand flexibility. In spite of many discussions about the concept of flexibility, the few mathematical definitions of flexibility available do not address the variation in time of the overall demand aggregation. This paper starts from the analysis of time-variable patterns of aggregate residential customers, ending up with suitable definitions of expected flexibility for aggregate demand. These definitions are based on assessing positive and negative pattern variations and are identified from the analysis of the collective behavior of the aggregate users. A set of results is shown for different numbers of aggregate customers, by considering different values of the averaging time step for load pattern representation.

When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighboring substations. In this paper the problem of fault current distribution is introduced, the test system is described and the measurements results are presented.

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.

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 the best slope of the supply function with the help of changing the intercept, and the method can be applied on the large systems. The approach proposed is applied to study IEEE-118 bus test systems and the comparison between bidding slope and bidding intercept is presented, as well, with reference to the test system.

Drawbacks of traditional “rate of return” (ROR) regulation for distribution system operators (DSOs) have given birth to performance based regulations (PBRs), among which are price cap (PC), yardstick competition (YC), and quality regulation (QR). The PC method may be affected by information asymmetries between the regulator and DSOs and the integration of YC, a regulatory policy that makes the regulated DSO competing with a virtual competitor, partly solves this problem. QR also needs to be considered to ensure that the improvement of economics does not jeopardize quality. Thus, it seems appropriate to integrate the three PBRs to strive contemporaneously for economic and technical good performance. This paper aims to model the distribution system competition under the integrated PC, YC, and QR regulatory scheme, allowing for quantitative estimation of DSO's performance. We develop a comprehensive model to represent virtual competition under the integrated regulatory paradigm, capable of capturing the interaction among various DSOs, which is modeled as a Nash game where all the DSOs endeavor to reduce cost for profit maximization. The model is used to capture the impacts of various parameters on the technical and economic performances. An application of the model to real 5-DSOs case is provided and discussed. Copyright © 2010 John Wiley & Sons, Ltd.

The extension of active noise control (ANC) techniques to deal with nonlinear effects such as distortion and saturation requires the introduction of suitable nonlinear model classes and adaptive algorithms. Large sized models are typically used, resulting in an increased computational load, delayed convergence (and sometimes even algorithm instability), and other unwanted dynamical effects due to overparametrization. This paper discusses the usage of polynomial nonlinear autoregressive models with exogenous variables (NARX) models and model selection techniques to reduce the model size and increase its robustness, for more efficient and reliable ANC. An offline procedure is devised to identify the controller model structure, and the controller parameters are successively updated with an adaptive algorithm based on the error gradient and on the residual noise. Simulation experiments show the effectiveness of the proposed approach. A brief analysis of the involved computational complexity is also provided.

The new scenarios of malicious attack prompt for their deeper consideration and mainly when critical systems are at stake. In this framework, infrastructural systems, including power systems, represent a possible target due to the huge impact they can have on society. Malicious attacks are different in their nature from other more traditional cause of threats to power system, since they embed a strategic interaction between the attacker and the defender (characteristics that cannot be found in natural events or systemic failures). This difference has not been systematically analyzed by the existent literature. In this respect, new approaches and tools are needed. This paper presents a mixed-strategy game-theory model able to capture the strategic interactions between malicious agents that may be willing to attack power systems and the system operators, with its related bodies, that are in charge of defending them. At the game equilibrium, the different strategies of the two players, in terms of attacking/protecting the critical elements of the systems, can be obtained. The information about the attack probability to various elements can be used to assess the risk associated with each of them, and the efficiency of defense resource allocation is evidenced in terms of the corresponding risk. Reference defense plans related to the online defense action and the defense action with a time delay can be obtained according to their respective various time constraints. Moreover, risk sensitivity to the defense/attack-resource variation is also analyzed. The model is applied to a standard IEEE RTS-96 test system for illustrative purpose and, on the basis of that system, some peculiar aspects of the malicious attacks are pointed out.

Power transmission grids play a crucial role as a critical infrastructure by assuring the proper functioning of power systems. In particular, they secure the loads supplied by power generation plants and help avoid blackouts that can have a disastrous impact on society. The power grid structure (number of nodes and lines, their connections, and their physical properties and operational constraints) is one of the key issues (along with generation availability) to assure power system security; consequently, it deserves special attention. A promising approach for the structural analysis of transmission grids with respect to their vulnerabilities is to use metrics and approaches derived from complex network (CN) theory that are shared with other infrastructures such as the World-Wide Web, telecommunication networks, and oil and gas pipelines. These approaches, based on metrics such as global efficiency, degree and betweenness, are purely topological because they study structural vulnerabilities based on the graphical representation of a network as a set of vertices connected by a set of edges. Unfortunately, these approaches fail to capture the physical properties and operational constraints of power systems and, therefore, cannot provide meaningful analyses. This paper proposes an extended topological approach that includes the definitions of traditional topological metrics (e.g., degrees of nodes and global efficiency) as well as the physical/operational behavior of power grids in terms of real power-flow allocation over lines and line flow limits. This approach provides two new metrics, entropic degree and net-ability, that can be used to assess structural vulnerabilities in power systems. The new metrics are applied to test systems as well as real power grids to demonstrate their performance and to contrast them with traditional, purely topological metrics.

The special features of electricity such as non-storability and lack of good substitutes, the network related market power and the demand inelasticity result in high volatile electricity prices in pool markets, especially during peak hours. Demand response (DR) programs with the aid of distributed energy resources (DER) provide the means to increase demand elasticity and, as a consequence, to counteract the effect of market power. This paper aims to assess the effectiveness of DR programs and try to answer to what extend DR programs will increase the demand elasticity and to what degree it will reduce the market power. Two DR programs, that is, time of use (TOU) rate and economic load response program (ELRP) are considered in this paper and the possible price responsiveness of load is modeled as linearly correlated to the difference of day and night TOU rate and the compensation price of load curtailment in order to determine the demand elasticity frontier. Game theory is employed to model the strategic bidding of generation companies (GenCos) and the Lerner index is used to quantify the market power. The proposed model is applied in Italian electricity market for numerical study. Copyright © 2008 John Wiley & Sons, Ltd.

This paper discusses the technical considerations when SOFCs are used for mixed DG/backup power applications, where the SOFCs work as distributed generators that output power to the grid when the grid is connected, while pick up the critical load in an acceptable time scale and continue the power supply to this critical load during a grid blackout. The principle of SOFC power generation is described, with reference to a prototype of a real 110 kWe tubular SOFC combined heat and power system, which is manufactured by Siemens Westinghouse and has operated at TurboCare S.p.A (Siemens Group) Turin, Italy. The technical requirements for a mixed DG/backup power system are presented and the system structure is detailed with special consideration of the technical aspects of the power conditioning systems. Simulation results based on a Matlab/Simulink model are reported assuming a grid blackout and a step increase of the critical load.

The paper analyses innovation features in the German financial sector. The first topic is persistence of innovation. Our research question is: Do innovators plan further innovation for the subsequent year? In addition, since the sector is so far poorly researched, very basic questions are investigated in the paper: the relationship between firm size and innovation (both linear and quadratic), as well as the impact of market structure on innovation (i.e. Schumpeterian and neo-Schumpeterian hypotheses). Finally, Suttons argument of R aamp;amp; D sunk costs is investigated as a possible explanation for persistence. Basing on the CIS IV survey, our empirical evidence is consistent with the results of similar researches carried out in different sectors.

The network structure of the power system, in an electricity market under the pool model, may have severe impacts on market performance, reducing market efficiency considerably, especially when producers bid strategically. In this context network re-enforcement plays a major role and proper strategies of transmission planning need to be devised. This paper presents, for pool-model electricity markets, two heuristic procedures to select the most effective subset of lines that would reduce the impacts on the market, from a set of predefined candidate lines and within the allowed budget for network expansion. A set of indices that account for the economic impacts of the re-enforcing of the candidate lines, both in terms of construction cost and market efficiency, are proposed and used as sensitivity indices in the heuristic procedure. The proposed methods are applied and compared with reference to an 18-bus test system.

The electricity market has been widely introduced in many countries all over the world and the study on electricity price forecast technology has drawn a lot of attention. In this paper, with different parameter Ci and ei assigned to each training data, the flexible Ci Support Vector Regression (SVR) model is developed in terms of the particularity of the price forecast in electricity market. For Day Ahead Market (DAM) price forecast, the load, time of use index and index of day type are taken as the major factors to characterize the market price, therefore, they are selected as the inputs for the flexible SVR forecast model. For the long-term price forecast, we take the reserve margin R m , HHI and the fuel price index as the inputs, since they are the major factors that drive the market price variation in long run. For short-term price forecast, besides the detailed analysis with the young Italian electricity market, the new model is tested on the experimental stage of the Spanish market, the New York market and the New England market. The long-term forecast with the SVR model presented is justified by the forecast with the data from the Long Run Market Simulator (LREMS). r 2007 Elsevier B.V. All rights reserved.

This paper deals with the definition of demand flexibility time intervals. These intervals are extracted from the binomial probability model of load variation patterns with the two possible categories of increase and non-increase in demand. These intervals along with the information on the coefficient of variation of the aggregate demand are used to assess the potential of demand flexibility exhibited by the aggregate residential demand in different periods of the day. The results of the proposed approach are useful for the distribution system operator or an aggregator to effectively set up demand response programmes in suitable time slots of the day.

Contrary to expectations, the development of smart (mini) grids is slow. Due to drastic improvements in innovative technologies, the reasons are not strictly technical but the problem mainly lies in regulatory barriers. The current business models are centric to utilities rather than customers. Net metering is a key enabling factor for smart (mini) grids. This paper addresses the economic benefits of net metering for individual residential customers. Energy demand for the individual apartments and common areas is calculated using the daily energy consumption behavior of occupants for typical days of each month of the year. Photovoltaic generation is estimated via PVGIS for a residential building in Italy. The proposed net metering scheme is applied on the aggregate energy demand of selected building without any modification in the current energy billing and net metering tariffs. Results show the noticeable difference in the savings of individual apartments.

For distribution system studies, a relevant aspect is the characterisation of the aggregate demand in a feeder. The probabilistic model of the aggregate demand is very useful for system operators or aggregators to extract information about the demand side behaviour in the operation of smart grids and microgrids. The time step used to scan the aggregate demand pattern is very important to preserve the information about the consumers’ behaviour and the related uncertainty. The conventional models of aggregate electrical demand consider an average value for a specific time step (e.g. 30 min to 1 h). In this study, a faster time step (1 min) is considered to construct a time-coupled probabilistic model of the aggregate residential demand based on Beta distributions. For a given number of aggregate loads, the parameters of the Beta distributions are found by taking into account the aggregate demand pattern variations at two successive time steps. The probabilistic model is then used to generate a number of aggregate demand scenarios. The effectiveness of the proposed scenario generation method is evaluated by using goodness of fit tests such as the Kolmogorov–Smirnov test and the average mean absolute percentage error.

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.

When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighbouring substations. In this paper the problem of fault current distribution is introduced, the test system is described and the measurements results are presented.

The present paper presents the preliminary results of the ongoing Italian METERGLOB project on the contribution given by the exposed conductive parts to a Global Grounding System. One of the expected results of METERGLOB is to carry out guidelines for the identification of a Global Grounding System. These guidelines must be defined on the basis of the definitions and methods present in the current international standards on grounding and safety. In the paper some definitions and elements to be taken into account for the identification of a Global Grounding System are given.

The adequacy of a Grounding System (GS) to the safety conditions has to be periodically tested by measurements. The test methods and techniques used to verify the electrical characteristics of the GS include the measurements of step and touch voltages. The goal of the test is to verify that touch voltage and step voltage remain below a safe value in all the zones of the installation. The measurements can present some operational difficulties. The purpose of this paper is to present the procedure, step-by-step, of a practical method of measuring touch/step voltages in grounding systems located in urban or industrial areas with reduced accessibility. The suggested method uses auxiliary current electrodes located at short distances. This paper demonstrates by test measurements done in a real case that the method provides conservative results.

In a competitive electricity market, the oligopoly structure of the market and the network constraints may produce results far from the perfect competition. This paper presents a comprehensive approach to evaluate the performances of the electricity markets with network representation in presence of bidding behavior of the producers in a pool system. A supply function strategic bidding model for the producers is introduced, and then different scenarios in terms of bidding behavior and network constraints are studied and compared on the basis of a set of microeconomic metrics. The aim of the paper is to assess, throughout a set of proper indices, the level of competition in a network-constrained market considering strategic behavior of the producers. The approach proposed gives the possibility to assess the different weight of strategic behavior of the producers and of the network constraints in distorting the market performances from its perfect competition equilibrium. From such an analysis, the worsening of the market efficiency and performances, due to the joint effects of the nonperfect competition and the network constraints, may be assessed and quantified, providing information on the adequacy of the grid considered for accommodating a competitive market. The exploitation of the proposed metrics for the market analysis is shown with reference to the IEEE 30-bus test system with demand elasticity explicitly represented.

Electrical load patterns that represent the consumption level are affected by different types of uncertainties associated with customer's behavior and with keeping acceptable comfort level. The resulting aggregated load pattern indicates the system response that may be more or less flexible in different periods of time. Many research activities have been dedicated to explore the flexibility of load demand using load patterns and associated uncertainties but little work is found on investigating the effect of sampling time and aggregation level on the shape of the load patterns. Knowing the characteristics of the electrical load patterns is a key aspect to manage load and supply side flexibilities for most economic system operation. This paper addresses the effects of sampling interval as well as aggregation level on the characteristics of the aggregated load patterns. The study is carried out on the basis of comprehensive statistical computations on collected data using load variation profiles, because these profiles embed the information on the load variation trend. The findings of this study may be used for load forecasting and management, generation allocation and economic operation of smart grid system, especially for microgrids.

The electrical load in residential systems highly depends on various types of uncertainty due to the lifestyle of the residential customers. Enhancing the knowledge on the aggregated behavior of these customers is particularly important for the distribution system operator, also with the aim of determining the potential flexibility of the residential demand and setting up the economic terms of the electricity provision to the customers. This paper addresses the impact of the sampling time interval with which the customer data are gathered on the characteristics of the aggregated electricity demand. A dedicated statistical analysis has been carried out to highlight the load variations occurring for different numbers of aggregated extra-urban residential customers. The results are represented in the form of normalized percentage load variations, using the number of samples and the maximum demand variation to construct the normalizing factor. The results indicate how the sampling time interval affects the load variations for different levels of customer aggregation.

The demand side in a power system has key importance in the evolving context of the energy systems. Exploitation of possible flexibilities of the customer's behavior is considered as an important option to promote demand response programmes and to achieve greater energy savings. For this purpose, the first action required is to augment availability of information about consumption patterns. The electricity consumption in a residential system is highly dependent on various types of uncertainties due to the diverse lifestyle of customers. Knowledge about the aggregated behavior of residential customers is very important for the system operator or aggregator to manage load and supply side flexibilities for economic operation of the system. In this paper, the effect of sampling time is evaluated for different residential load aggregations using probabilistic approach. A binomial probability distribution model is used to extract trends in increase or decrease in demand with respect to time evolution of a typical day. For each case study scenario, confidence intervals are calculated to assess the uncertainty and randomness in load variation trends. The findings of this study will lead towards better management of demand and supply side resources in a smart grid and especially for microgrids.

Descrevemos o caso de uma paciente de 42 anos portadora de cisticerco racemoso na região do ângulo ponto-cerebelar (APC) direito com trigeminalgia bilateral mais intensa no lado ipsilateral à localização do parasita. O cisticerco foi totalmente removido por meio de craniotomia suboccipital. No primeiro dia pós-operatório houve desaparecimento bilateral da dor. Duas hipóteses fisiopatológicas foram aventadas para explicar a sintomatologia: lesões que ultrapassam os limites da cisterna do APC poderão através da cisterna pré-pontina alcançar a cisterna do APC atingindo o trigêmeo contralateral; lesões com grande efeito de massa poderão provocar rotação do tronco cerebral e deslocamento e tração de estruturas ipsi e contralaterais, provocando compressão arteriovenosa sobre o trigêmeo contralateral na porção superior da cisterna do APC. Salientamos a necessidade de exames de imagem ante qualquer algia craniofacial e observamos que, em lesões na região do APC, a cisticercose não pode ser esquecida.

Economic dispatch (ED) is the generation allocation problem subject to various constraints. The actual behaviour of thermal generators is non-convex but cost characteristics are typically approximated to convex ones in the analysis. So the results obtained through optimization techniques can be inaccurate. Dynamic programming has been used to solve non-convex ED, but it suffers from the curse of dimensionality. The non-convex ED problem is generally solved by using artificial intelligence (AI) tools and hybrid approaches. Among them, the Virtual Bees (VB) algorithm has been used for the solution of complex optimization problems. This paper presents a New Sequential VB-VB algorithm to solve convex as well nonconvex ED. Standard IEEE test systems have been tested with convex and non-convex ED problems for the validation of this approach. The numerical results obtained indicate the validity of the proposed algorithm in comparison with other state of the art techniques.

In voltage stability analysis, both static and dynamic approaches are used to evaluate the system critical conditions. The static approach is based on the standard load flow equations. For small-disturbance analysis, the dynamic approach is based on the eigenvalue computation of the linearized system, while for large-disturbance analysis a complete time-domain simulation is required. However, both the equilibrium point around which linearization is performed and the initial conditions for the simulation are computed by a procedure which uses the standard load-flow equations. The standard load-flow equations make some implicit assumptions on the steadystate behaviour of dynamic components (generator control systems, loads). These assumptions are not satisfied by the usual dynamic models, and this discrepancy leads to different results in the voltage stability assessment using static and dynamic methods. In the framework of bifurcation theory, this paper discusses the relationships between static and small-disturbance dynamic approaches to find the voltage stability critical condition, with emphasis on system component modelling. A set of hypotheses on generator control systems and load models is given for a multimachine system, according to which the same critical conditions are obtained both from the load flow equations and from the full eigenvalue analysis. These hypotheses are less restrictive than those previously proposed in the literature and make it possible to obtain equivalence between the singularity of the load flow Jacobian and a null eigenvalue of the linearized dynamic system. Following a dynamic argumentation based on small-disturbance analysis, this result may justify the use of simple and fast static methods for voltage stability assessment and shows that the smalldisturbance voltage stability limit depends only on the steady-state characteristics of the dynamic components of the system.

The current work focuses on two specific issues concerning grid-connected solar PV units, i.e. the fault ride-through capability, also called low voltage ride-through capability, and the voltage support function through reactive power injection during faults. With the first one the PV unit can actually provide some limited grid support, whereas with a defined reactive power characteristic it can give a complete dynamic grid support. These two requirements, already known for wind power generation but new for the PV, have been recently introduced in the German technical guidelines for connection to the MV grid. Scope of the paper is to implement these requirements in a large solar PV plant, modeled in DIgSILENT PowerFactory, in order to understand its operation, and to evaluate its behavior and impact on the grid, in terms of stability and voltage support during grid fault.

The present study, upon trying to explain the nature of innovation in the banking sector, also aims at verifying if banks are in fact as innovative as statistics based on CIS (Community Innovation Survey) in several European countries suggest (Napoli, 2008b). Furthermore, the present work also contributes to the theoretical debate. In fact, a new view is proposed in order to assess innovativeness of banks, which bases on their propensity to finance innovative projects. With their allocating decisions, financial intermediaries act as a multiplicator of innovative capacity and hence overtake a leading role in driving innovative forces.

Power system vulnerability is a key concern in modern societies and many efforts have been devoted to its analysis. Recently, the wide domain of complex networks that can be used to assess the vulnerability of network systems has been applied to power grids as well with focus on the topological vulnerability of the transmission systems based on its structure in terms of the nodes and their connection patterns. However, a pure topological approach, as proposed in the current literature, fails in capturing the specific features of power systems. The authors propose an extended topological approach, which can incorporate several important features of the power grids such as flow paths, line flow limits and gen/load bus distribution. Also, a set of new metrics able to provide an assessment of the system vulnerability is defined. ‘Net-ability’ measures the aptitude of the grid in transmitting power from generation to load buses efficiently. ‘Path redundancy’ assesses the available redundancy in terms of paths in transmitting power from a generation to a load bus based on entropy. Based on the previous two metrics, the authors introduce a third metric, the ‘survivability’, as a global metric to evaluate the aptitude of the network in assuring the possibility to match generation and demand in case of failures or attacks. The metrics proposed will be applied to different test systems and to a real-transmission system to illustrate their application and effectiveness.

Critical infrastructures are usually characterized by a network structure in which many technical devices interact on a physical layer, being monitored and controlled throughout a cyber network in charge of conveying commands/measurements from/to the decision making centers run by the human decision makers or automatic controllers at the top of this complex system.

Competition has been introduced in the electricity markets with the goal of reducing prices and improving efficiency. The basic idea which stays behind this option is that, in competitive markets, a greater quantity of the good is exchanged at a lower and stable price, leading to higher market efficiency. Electricity markets are different from other commodities mainly because of the operational characteristics, perishability and lack of large storage capability, which may impact the market performances. The network structure of the system on which the economic transactions need to be undertaken poses strict physical and operational constraints. Those physical and operational constraints need to be ensured to guarantee an operating state feasible and when those constraints binding the congested system show remarkable economic impacts. Strategic interactions among market participants with the objective of maximising their surplus must be taken into account when modelling competitive electricity markets. The network constraints, specific of the electricity markets, provide opportunity of exercising strategic behaviour of the market participants. Game theory provides a tool to model such a context. This study provides a comparative analysis of the application of game theory models to network constrained electricity markets with the focus on the strategic behaviour of the electricity producers. Different models such as supply function equilibrium, Cournot, Stackelberg and conjecture supply function are considered and their appropriateness to model the electricity markets is discussed. Under network constraints with reference to the IEEE 30- and IEEE 57-bus test systems, various models are compared in quantitative way to provide analysis of the market performance under different representation of the oligopoly competition in the electricity markets.

Security management is of the utmost importance in power system and many efforts have been made on this issue since a reliable supply of electricity is crucial to the modern societies. The traditional approach adopted in Europe is based on the “n − 1” steady-state security that is efficient, although restrictive, and can continue to play an important role also in the new competitive context. In this paper, three alternative market-based models for security consideration are introduced, according to preventive and corrective control approaches. The models are presented and analyzed in terms of their economic impacts on the market throughout a set of useful indexes that allows for a ranking of the advantages got from the re-enforcement of the lines. Moreover, the positive impacts of the phase-shifter (PS) installation for the security and congestion management are quantified and indexes are derived to assess their optimal location. The different models and the exploitation of the proposed indexes are illustrated with reference to a 34-bus test system. Copyright © 2008 John Wiley & Sons, Ltd.

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 more specific features that can not be reflected in generic perspective. This paper proposes several most serious obstacles for applying CN to analysis of vulnerability for power grids. Based on the proposed solutions for these obstacles, specific concept of network performance to indicate power supply ability of the network will be defined. Furthermore, the proposed method will be investigated by a 34-bus test system in comparison with the result from general concept of efficiency in CN to indicate its effectiveness.

Due to the extreme importance of the power system, the operation of the electricity market has drawn much concern. The introduction of the electricity market aims to improve the efficiency, but meanwhile has brought many new problems, which cannot be found in the traditional monopoly system. Especially, in the economy aspect, power system has to face market risk other than the physical security problem. To find proper measures for market realization and adjustment, the authority should examine them carefully before their implementation. An electricity market monitoring system, which on one hand provides the references for market participants making strategic decisions and on the other hand is able to evaluate the impacts of specific measures or market context variation, is presented in this paper to help the regulator make decisions on market policy and the market participants foresee the market evolution. The monitoring system consists of two units, one is the market simulator, which detailed models the interaction between the market players by game theory and multi-agent system; the other is price forecast, which interprets the market evolution by mathematical or artificial intelligence approaches to foresee the prices. The two units cooperatively build a monitoring system for predicting the future market scenarios in different respects. Results of the numerical examples applying the preliminary monitoring system are presented and illustrated.

Malicious attacks against critical infrastructures, and power systems as well, became a key-concern in recent years. The attacks may be both “physical,” directed towards system components, and “cyber,” against the information/communication system; simultaneous attacks to different components, both physical and cyber, may be possible. In this context, the assessment of the vulnerability of a given interconnected power system, in terms of the possibility to keep it feasible after a defined attack, w.r.t a limited number of information available (both due to attacks or a regulatory rule) is of the utmost importance. In this paper, we propose a game model, based on the socially rational multi-agent system (MAS) and fictitious play, which can be used to assess the sensitivity of the system structure and operational state to various availabilities of network information. From the model both a ranking of the critical information and a strategy of network reinforcement to decrease system vulnerability can be derived. The proposed model and methods are applied to a 34-buses test system for illustrative purposes. Copyright © 2008 John Wiley & Sons, Ltd.