Analisi dell'accumulo elettrochimico ad alta temperatura per l'integrazione delle fonti rinnovabili nella rete di trasmissione nazionale

This PhD thesis analyses the compatibility of large scale installations of the Na-beta technology for electrochemical stationary storage of electrical energy in the high voltage network, in order to support the electrical system in the management of the renewable energy sources. The reliability, the safety and the environmental compatibility of the two Na-beta batteries, i.e. the sodium-nickel chloride and the sodium-sulphur ones, were deeply analysed by means of detailed risk analysis. Moreover, an innovative modelling approach based on matrixes is presented for sodium-nickel chloride technology, which could be easily extended to the sodium-sulphur batteries, considering the similarities of these two technologies. Furthermore the presented modelling approach was validated by comparing the electrical model results with experimental measurements carried out in collaboration with Terna (the Italian Transmission System Operator) in the ENEA laboratories in Rome. A 7.8 kW module was tested and the agreement between measurements and the model results was very good

Synergy of the future: High voltage insulated power cables and railway-highway structures

The rationalisation of the territorial resources leads to consider carefully the possibilities of using motorway and railway infrastructures (existing or planned ones) for cable line installation within them. The full compatibility of such synergy \u2018transport \u2013 electrical power transmission\u2019 involves different branches of engineering. The study provides an overview of the research undertaken for a fully reliable use of this combination. The manuscript aims at highlighting a procedural approach that should be followed in order to analyse all the key elements involved in the safe operation of power transmission lines hosted in transport infrastructures. First, the geometrical compatibility between different types of power transmission technologies, (i.e. gas insulated lines and high-voltage direct/alternating current insulated cable lines), and transport infrastructures (i.e. motorway galleries, railway galleries and railway prospection tunnels) is considered. Subsequently, the behaviour and magnitude of the magnetic field generated by the different power transmission technologies inside the transport infrastructures are presented. Moreover, the study analyses the effects of a phase-to-screen short circuit that could occur inside the hosting facility. Finally, an analysis of the reliability of the synergy between power transmission systems and transport infrastructures is discussed

Review of Power Conversion and Conditioning Systems for Stationary Electrochemical Storage

This paper deals with the power conversion system architectures to interface a stationary electrochemical storage installation with the network. Theoretical justifications about the conversion system layouts and control, used for actual Italian installations, are given. This paper aims at giving the power energy society an overview of actual possibilities of static conversion of d.c. battery sources

A Novel Modeling for Assessing Frequency Behavior During a Hydro-to-Thermal Plant Black Start Restoration Test

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

Analisi dell'accumulo elettrochimico ad alta temperatura per l'integrazione delle fonti rinnovabili nella rete di trasmissione nazionale

This PhD thesis analyses the compatibility of large scale installations of the Na-beta technology for electrochemical stationary storage of electrical energy in the high voltage network, in order to support the electrical system in the management of the renewable energy sources. The reliability, the safety and the environmental compatibility of the two Na-beta batteries, i.e. the sodium-nickel chloride and the sodium-sulphur ones, were deeply analysed by means of detailed risk analysis. Moreover, an innovative modelling approach based on matrixes is presented for sodium-nickel chloride technology, which could be easily extended to the sodium-sulphur batteries, considering the similarities of these two technologies. Furthermore the presented modelling approach was validated by comparing the electrical model results with experimental measurements carried out in collaboration with Terna (the Italian Transmission System Operator) in the ENEA laboratories in Rome. A 7.8 kW module was tested and the agreement between measurements and the model results was very good.In questa tesi viene analizzata la compatibilità  della tecnologia di accumulo elettrochimico stazionario dell'energia elettrica nota come Na-beta per installazioni su larga scala sulla rete elettrica di trasmissione allo scopo di supportare il sistema elettrico nella gestione delle problematiche relative alla sempre maggiore penetrazione di fonti di energia rinnovabile sulla rete. Dettagliate analisi di rischio sono state condotte in collaborazione con le aziende produttrici sulle due tipologie di batterie Na-beta, ovvero quella sodio-cloruro di nichel e quella sodio-zolfo per valutare l'affidabilità nell'esercizio, la sicurezza per le persone e la compatibilità ambientale. Viene inoltre presentato un approccio di modellizzazione matriciale innovativo per la tecnologia sodio-cloruro di nichel, facilmente estendibile alle batterie sodio-zolfo date le caratteristiche molto simili delle due tecnologie. Il modello realizzato, di tipo elettrico, è stato validato mediante confronto dei risultati con misure sperimentali effettuate in collaborazione con Terna nei laboratori ENEA di Roma su di un modulo da 7,8 kW, dando un'ottima concordanza sia in regime permanente che transitorio

Studio multiconduttore matriciale di cavi sottomarini in corrente alternata

L’oggetto di questa tesi è la creazione di un modello basato sul metodo matriciale multi conduttore in grado di rappresentare un collegamento in cavo in corrente alternata. In particolare il modello è stato applicato ad una linea sottomarina facente parte del rafforzamento del collegamento Sorgente-Rizziconi,tra Calabria e Sicilia,a 380 kV. Utilizzando la procedura elaborata è possibile calcolare gli andamenti di tensione e corrente su tutti gli elementi conduttivi dei cavi, lo studio dell’impedenza in frequenza per individuare possibili effetti di risonanza ed il calcolo delle impedenze alle sequenze tenendo conto dell’influenza di schermi ed armature. Il modello è stato confrontato con gli andamenti del software commerciale EMTP dando un’ottima concordanz

A New Multiconductor Cell Three-Dimension Matrix-Based Analysis Applied to a Three-Core Armoured Cable

In this paper, a procedure based on three-dimension matrices is presented: it is the generalization of multiconductor cell analysis to any transmission line where the positions of all the active and passive conductors may change with continuity along their length. A meaningful example of this is given by a three-core single lead-screened armoured cable where cores and armour wires are wound helically with different lay lengths. Therefore, this generalization is presented with reference to these cables but it can be applied to any transmission line. The proposed matrix procedures can be implemented in any standard computer by means of a mathematical software (e.g. Matlab). The computational complexity of this novel method is shown in comparison with the finite element method commercial software FLUX 3D which takes 70 h for meshing and solving a 3 m long model. On the contrary, the present matrix algorithms take from minute fractions to maximum 2 minutes (depending on subconductor number) to obtain results having negligible differences with respect to FEM FLUX 3D ones if paramagnetic materials are involved and differences up to maximum 7 % with ferromagnetic ones (which imply, for submarine cable installations, a current rating computation difference lower than 3%)

The Ossanna's theorem for educational purposes: Impact of distributed parameter transmission lines on power systems

This paper faces a challenge in power education: how to teach the students the impact of different transmission lines on the power system at power frequency. More specifically, the paper exploits the very effective and elegant Ossanna's theorem in order to make clear which are the allowable electrical regimes of different transmission line typologies in terms of power losses, voltage drops, transmissible powers and the conditions for the voltage collapse. Moreover, the formulation of the complex power at the sending-end of the power transmission line inferred from the Ossanna's theorem, which has never been shown in technical literature, is clearly presented. It is worth noting that although the paper is focused on high and extra-high voltage transmission lines, the presented didactical approach can be indifferently applied to any voltage level

Determination of Steady-State and Faulty Regimes of Overhead Lines by Means of Multiconductor Cell Analysis (MCA)

Single-phase positive sequence modelling is often used in power systems when power flows and short circuit analysis are assessed. Of course, the use of single-phase positive sequence modelling assumes purely three-phase configurations and perfectly symmetrical ones so that single-phase modelling considers that all the phase conductors behave in the same way. When considering the physical reality of power networks, this assumption can be questionable and the behaviors of all the system conductors including the passive ones (earth wires for overhead lines, metallic screens and armours for cables and enclosures for gas insulated lines) is completely unknown. Therefore, the present multiconductor cell analysis (MCA) becomes necessary, since it allows one to achieve great precision results on the regimes of both phase conductors and passive conductors. MCA offers a powerful tool in order to validate (or less) approximated and simplified computation methods. In particular, for single and double circuit overhead lines (OHLs), the current phasors induced in the earth wires and the ground return current alongside the line can be directly computed by MCA in steady state and faulty regimes. It is worth noting that, for faulty regimes, MCA allows also evaluating the approximation degree and validity field of screening factors k

34,8 MW di accumulo elettrochimico di tipo ENERGY INTENSIVE mediante celle secondarie sodio-zolfo (Na-S)

In questo articolo sono esposti sinteticamente parte degli studi condotti per la verifica della compatibilit\ue0 tecnica, normativa e ambientale delle celle secondarie sodio-zolfo con installazioni di tipo Energy Intensive sulla rete italiana di AT