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Northern electric grid of Italy was involved in a black start mock drill. This test took place on November 2016 in order to check the coordination and efficiency of all the operational staffs and the automatic regulators involved in the case of a real blackout scenario. This paper presents the results of a research carried out in collaboration with Terna Rete Italia (the Italian Transmission System Operator), in order to find strengths and weaknesses and eventually to upgrade the existing restoration plan. Starting from the measures coming from generating plants and substations bars, the model of frequency regulation system for both the participating hydro and thermal power plants is developed. This work gives the system operator an essential tool to understand many complex dynamics and phenomena occurred during the test. At the same time, a robust model simulating the system behavior with different grid configurations is presented: it gives the opportunity to enhance both the classical power system control theory and the black start practices.

In this paper the sequence impedances of an existing HVAC insulated cable, protected by a steel reinforced concrete structure, are estimated. The paper aims at investigating if the presence of metallic protective structures significantly affects the sequence impedances of the line. The present analyses are carried out by applying both the multiconductor cell analysis and the finite element method in order to model the HVAC line with and without protective structure. The results arising from the use of the different modelling approaches are compared.

This study aims at evaluating the impact of the current changes in power generation on voltage sags (dips) in HV networks. This changing process started about 15 to 20 years ago and concerns the increasing diffusion of inverter-based generators (IBGs) and the contemporary reduction of synchronous generators (SGs). A major effect of this ongoing transition is the reduction of short-circuit currents/powers in the electrical grid, with consequent changes of the voltage sags caused by faults in the grid. This study is the first ste p of a larger research project involving the whole Italian HV network. The goal is a quantitative evaluation of the effects of the transition from an “old” power park (with only SGs) to a present power park (with less SGs and IBGs) on voltage sags in a HV network. In this paper, the analysis concerns the real HV network of Sardinia, which comprises 262 nodes altogether. Despite some simplifying assumptions, the results—consistent with the sag classification of the Standard EN 50160—give a clear and original quantitative evaluation of the negative effects of the considered change of produc tion units on voltage sags.

This paper presents a model for the study of bottom-up power system restoration tests. The model is built for quick and suitable validation of power-frequency correlation during a restoration test, the most stressed process into a system with low regulation energy. All involved components are modelled by SISO systems describing both power generation controls and load behaviours. The simulation results are widely discussed through the analyses of four load scenarios, with the aim of scanning all possible worst cases in terms of load steps.

The paper deals with the sequence impedances (positive/negative and zero sequences) of high- and extra-high-voltage land single-core insulated cables. In particular, it presents the comparisons between sequence impedance measurements and computations. The computations of the sequence impedances are carried out by means of the most important international normative and council references (IEC/Cigr&eacute, ) and of multiconductor cell analysis which is a consolidated and powerful tool developed by University of Padova in order to analyse power frequency regimes of multiconductor asymmetric power systems. The comparisons are presented with reference to four high- and extra-high voltage insulated cables, even if the available ones are much higher: however, the conclusions derived from these four reference cases are general and can be useful for transmission system operators and for power electric system engineers involved in insulated cables. The paper demonstrates, for the first time in technical literature, that direct formulae cannot correctly evaluate the sequence impedances of installed single-core land cable systems. Extensive on-field measurement campaigns have served to this purpose.

The transmission system is affected by natural phenomena that could endanger the electrical infrastructure causing damage to the equipment and affecting the security of supply. The present paper describes the effect on electricity assets of ice and snow and the main preventive measures that the Transmission System Operators (TSOs) can adopt in order to increase the resilience of the grid. The first part of the paper provides a general overview of the natural phenomena leading to wet and ice sleeves accretion around the conductors of the Overhead Lines (OHL), while the second part describes the most advanced solutions to prevent icing phenomena on OHL in terms of both operation grid schemes and anti-icing equipment.

This is a shrunken version of a full paper presented in IEEE Access [1]. This paper presents the results of a research carried out in collaboration with Terna Rete Italia (the Italian Transmission System Operator), in order to find strengths, weaknesses and eventually to upgrade the existing restoration plan. The aim of this research is the creation of a Simulink model in order to study the frequency behaviour during a real restoration test that involved northern Italy electric grid. Starting from the measures coming from generating plants and substations bars, the model of frequency regulation system for both the participating hydro and thermal power plants is developed. This work gives the system operator an essential tool to understand many complex dynamics and phenomena occurred during the test.

The CRISPR-Cas9 genome-editing tool and the availability of whole-genome sequences from plant species have revolutionized our ability to introduce targeted mutations into important crop plants, both to explore genetic changes and to introduce new functionalities. Here, we describe protocols adapting the CRISPR-Cas9 system to apple and grapevine plants, using both plasmid-mediated genome editing and the direct delivery of CRISPR-Cas9 ribonucleoproteins (RNPs) to achieve efficient DNA-free targeted mutations in apple and grapevine protoplasts. We provide a stepwise protocol for the design and transfer of CRISPR-Cas9 components to apple and grapevine protoplasts, followed by verification of highly efficient targeted mutagenesis, and regeneration of plants following the plasmid-mediated delivery of components. Our plasmid-mediated procedure and the direct delivery of CRISPR-Cas9 RNPs can both be utilized to modulate traits of interest with high accuracy and efficiency in apple and grapevine, and could be extended to other crop species. The complete protocol employing the direct delivery of CRISPR-Cas9 RNPs takes as little as 2-3 weeks, whereas the plasmid-mediated procedure takes >3 months to regenerate plants and study the mutations.

In this paper, two single-ended algorithms for fault location are presented with reference to the unearthed operated sub-transmission Italian grid (60kV). Both algorithms deals with the correlation between the charging frequency of sound phases to ground capacitances with the fault position. In the first one, the frequency response of a lumped parameter circuit in the Laplace domain is linked to the fault distance. In the second one, the frequency spectra of the transient current waveforms are used as a database for the training of an Artificial Neural Network, which identifies the fault distance by analysing the input data. The fault location accuracy of the two proposed methods are compared in order to reveal strengths and weakness of both algorithms. The developed procedures have been applied to an overhead line modelled in EMTP-rv environment, whereas the fault location algorithm has been implemented in Matlab environment.

In this paper a single-ended travelling wave-based fault location algorithm is presented with reference to HV (60 kV) overhead unearthed operated lines:the time-frequency characteristics of the travelling wave signal are processed by utilising the phase to modal transformation and the continuous wavelet one. The frequency components of the processed signals are used for the travelling wave speed calculation whereas the time components are used for determining the wave arrival times. The fault position is evaluated by combining these two aspects. The proposed approach has been tested in different conditions, in order to assess the method stability: it has been proven insensitive to the fault position, fault resistance and the fault inception angle.

Background Arundo donax L. (Poaceae) is considered one of the most promising energy crops in the Mediterranean region because of its high biomass yield and low input requirements, but to date no information on its transcriptional responses to water stress is available. Results We obtained by Illumina-based RNA-seq the whole root and shoot transcriptomes of young A. donax plants subjected to osmotic/water stress with 10 and 20 % polyethylene glycol (PEG; 3 biological replicates/organ/condition corresponding to 18 RNA-Seq libraries), and identified a total of 3034 differentially expressed genes. Blast-based mining of stress-related genes indicated the higher responsivity of roots compared to shoots at the early stages of water stress especially under the milder PEG treatment, with a majority of genes responsive to salt, oxidative, and dehydration stress. Analysis of gene ontology terms underlined the qualitatively different responses between root and shoot tissues. Among the most significantly enriched metabolic pathways identified using a Fisher’s exact test with FDR correction, a crucial role was played in both shoots and roots by genes involved in the signaling cascade of abscisic acid. We further identified relatively large organ-specific differences in the patterns of drought-related transcription factor AP2-EREBP, AUX/IAA, MYB, bZIP, C2H2, and GRAS families, which may underlie the transcriptional reprogramming differences between organs. Through comparative analyses with major Poaceae species based on Blast, we finally identified a set of 53 orthologs that can be considered as a core of evolutionary conserved genes important to mediate water stress responses in the family. Conclusions This study provides the first characterization of A. donax transcriptome in response to water stress, thus shedding novel light at the molecular level on the mechanisms of stress response and adaptation in this emerging bioenergy species. The inventory of early-responsive genes to water stress identified could constitute useful markers of the physiological status of A. donax and be a basis for the improvement of its productivity under water limitation. The full water-stressed A. donax transcriptome is available for Blast-based homology searches through a dedicated web server (http://ecogenomics.fmach.it/arundo/). Electronic supplementary material The online version of this article (doi:10.1186/s13068-016-0471-8) contains supplementary material, which is available to authorized users.

This paper provides a coherent classification of the existing methods for phase-to-ground fault location in power sub-transmission networks operated with unearthed neutral. The theoretical background of every approach is briefly presented, specifying whether each method is applicable on-line or off-line. The analysis is mainly focused on comparing the limitations of the algorithms, especially concerning the general properties of the lines of a sub-transmission power system.

This paper provides a coherent classification of the existing methods for phase-to-ground fault location in power sub-transmission networks operated with unearthed neutral. The theoretical background of each approach is briefly presented, specifying whether a method is suitable for on-line or off-line applications. The analysis is mainly focused on comparing the limitations of the algorithms, especially concerning the general properties of the lines of a sub-transmission power system. The aim of authors is to present an overview of the existing approaches in literature by identifying five method categories, i.e. signal injection method, impedance-based method, travelling wave method, fault transient analysis method and composite location method. The main pros and cons of each method are described in order to give the reader a useful guide to identify the better fault location procedure, on the basis of the user own needs.