1,721,017 research outputs found
A software-only PTP synchronization for power system state estimation with PMUs
No full textSynchronized Phasor Measurement Units (PMUs) are becoming a key element of monitoring, protection, control and state estimation applications in power systems and are the basis for the implementation of Wide Area Monitoring Systems (WAMSs). This paper investigates the possibility of using a software-only PTP (Precision Time Protocol) synchronization method to synchronize different Phasor Measurement Units (PMUs) and how this synchronization impacts the State Estimation. In this context, as a case study, the output data of the PMUs have been used to estimate the state of a power system of reduced size and complexity. A laboratory experimental setup has been built to evaluate the performance achievable with the proposed synchronization solution. The results thus obtained and the performance analysis are discussed in this paper
Optimal Scheduling of Electric Heat Pumps Combined with Thermal Storage for Power Peak Shaving
No full textWith the transition towards the smart grid paradigm, end-users are expected to play a more and more active role by offering their flexibility to support the efficient operation of electric networks. This paper investigates the potential given by a Demand Side Management program for the control of electric heat pumps combined with thermal storage aimed at reducing the power peaks in the grid. To this purpose, the assessment of the building thermal loads is performed according to the standard ISO 13790 and a mixed integer linear programming optimization is applied to schedule the operation of the electric heat pumps. Preliminary results show that decoupling thermal load and electricity consumption by using the thermal storage guarantees a large flexibility, which can be exploited to achieve important benefits at grid level without affecting the thermal comfort of final customers
A Distributed State Estimator for Electric Power Systems in Avionic and Naval Applications
No full textImpact of Different Uncertainty Sources on a Three-Phase State Estimator for Distribution Networks
No full textDistribution networks present their own features, significantly different from transmission systems features. For instance, loads are often unbalanced on the phases of the network. Moreover, the increasing amount of distributed generation, installed in an unplanned manner, is creating significant challenges. Such changing scenario imposes new operational requirements, such as distributed voltage control and demand side management. New performances are required for distribution system state estimators. In this paper, a study on the impact of different uncertainty sources on a state estimator designed for monitoring unbalanced distribution networks is presented. The impact of different measurement devices and levels of knowledge of the network behavior is analyzed and discussed using simulations performed on the 123-bus IEEE distribution network, which is commonly used as test network for this kind of stud
Effects Of PMU’s Uncertainty On Voltage Stability Assessment In Power Systems
No full textThere is a lack of information on the accuracy that is required to Phasor Measurement Units (PMUs) in the measurement of synchrophasors in order to use them correctly in the different applications on power systems. In this paper the use of PMUs for power system voltage stability assessment is considered. as a sample application. A small example network is adopted as case study, and the impact of PMU accuracy when used in this application is analyzed. Such analysis constitutes the first step to developing the background for both defining the performance characteristics for synchrophasor measurements used for instability detection and considering the robustness with respect to PMUs' uncertainty as a criterium for choosing the most suitable method for stability monitoring
Measurement issues for performance assessment in large photovoltaic plants
No full textThe role of measurements is crucial for performance assessment in PV plants. Measurements are of critical importance both on a preliminary stage of model validation and on the subsequent stage of on-line monitoring. Measurement issues are particularly critical above all in large PV plants, where different environmental, geometrical and technical conditions may coexist. This paper addresses such issues, focusing on the features of the measurement system that should be guaranteed to obtain cost-effective model validation and performance evaluation in a large PV plant, with specific reference to a 18 MW plant installed in the north of Sardinia (Italy)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Impact of synchrophasor measurement uncertainty on detecting voltage stability margin in power systems
No full textPhasor Measurement Units (PMUs) provide
synchronized phasors (synchrophasors) of voltage and current,
usually together with measurements of frequency and rate of
change of frequency. One of the main characteristics of the
PMUs is to provide synchronized and accurate measurement of
all these quantities with a reporting rate much higher than that
of traditional measurement systems. Also for this reason, PMUs
have been shown have a lot of potential in different
applications in power systems, including voltage stability
monitoring. As the uncertainty of the PMUs impacts the
monitoring performance, it is necessary to perform a thorough
analysis before the monitoring system can be designed and its
outcome used for control, particularly of critical applications.
Hence, this paper presents the analysis of the effect of the
uncertainty introduced by the PMUs, on a global method for
voltage instability detection. In particular, the Load Margin
Index based on wide-area phasor measurements is considered
as reference method. Several tests and results obtained on the
IEEE 39-bus system are presented and discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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