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The paper presents a modelling approach which, starting from experimental measurements, allows automatically deriving a lithium-ion battery electrical model. This procedure is applied to a 47.7 kW lithium-manganese oxide battery unit in order to infer a third-order Thevenin equivalent electrical model of the unit itself. By means of a matrix representation of specific experimental measurements, it...
Symmetrical monopolar HVDC links, based on Modular Multilevel Converters (MMCs) represent the state of the art for submarine and underground cable interconnections over long distances. MMCs exhibit significant advantages if compared to other converter topologies, such as lower losses, footprint and harmonic distortion. However, due to the use of a symmetrical monopolar arrangement, severe temporary...
The paper describes the instantaneous control technique of a two stage Power Conversion System interfaced to an energy storage equipment. The control aims at regulating the active and reactive power exchange between the grid and the converter during the battery discharge and charge operations. The results of the control implementation in a Simulink® model of the Power Conversion System are compared...
Electricity generation in small remote island is generally performed using diesel generators, leading to high energy cost and significant local pollution; the integration of renewable energy sources in such small networks is hindered by stability and reliability issues, as well as environmental constraints. The paper deals with the replacement of diesel generation in Giannutri (a small island in the...
The lightning performance of an EHV overhead transmission line (OHL) largely depends on tower grounding behavior; when high ground flash density values are expected, a proper design of grounding arrangements, focused on their high frequency behavior instead of the conventional power frequency analysis, can significantly reduce the backflashover rate (BFR) of the OHL. A technical optimization is reported,...
Electricity in small remote islands is generally supplied by diesel generators, leading to high energy cost and significant local pollution; the integration of renewable energy sources in such small networks is hindered by stability and reliability issues, as well as environmental constraints. The paper deals with the replacement of diesel generation in Giglio (a small island in the Tyrrhenian Sea),...
The paper present a preliminary study of the protective relays of a 10 MW sized battery energy storage system (BESS) recently installed by TERNA, the Italian TSO. A complete model of the system, including inverters, has been implemented in ATP-EMTP in order to assess the behaviour of protective relays during symmetric and asymmetric faults. Results show that ground fault protection of MV feeders can...
The paper presents an economic study concerning the replacement of HV/MV power transformers (TRs) according to the requirements recently introduced in the Commission Regulation EU n°548/2014 (Tier I and Tier II class transformers). Two case studies based on measured yearly load profiles of existing TRs, referring to two primary substations in a MV distribution network, have been carried out. A Monte...
This paper deals with the arc-flash haz ard calculation in battery energy storage systems (BESSs). The lack of international harmonized standards, coupled with a foreseeable increasing use of BESSs, makes this subject very interesting, especially due to the practical involvements related to arc-flash hazard associated with BESS maintenance operation. A Li-ion battery circuit model, based on experimental...
Reliability of underground Extra High Voltage (EHV) cable systems is undermined by third party mechanical damages. In order to prevent long and expensive outages, the Italian TSO equipped some cable lines of strategical importance with additional protective structures. The presence of highly permeable and conductive material surrounding the cable installations has risen concerns about potential variations...
The paper presents the analysis of Sodium Nickel chloride batteries in transient operation, and proposes a very simple but quite precise model to represent both the transient and steady battery behaviours. The used modelling approach is based on steady state experimental measures. Sodium Nickel chloride batteries are one of the most promising technologies for electrical energy stationary storage in...
The sudden development of distributed generation from renewable energy sources, mainly windfarms, can cause congestions on the existing transmission grids. Due to the difficult authorization procedure for the construction of HV overhead lines, or even for the refurbishment of the existing ones, Battery Energy Storage Systems (BESS) can be an useful solution to local congestions. NaS batteries are...
Submarine interconnections allow for the connection of large islands to the onshore transmission grid and for the decommissioning of local power plants, which are often old, inefficient and polluting. High voltage alternating current (HVAC) cables are an interesting solution for smaller power ratings and distances up to 120 km, due to lower capital costs and absence of converting stations, if compared...
Fast charging station will play a key role in the widespread diffusion of electric vehicles in large cities. Large public parking areas, such as park-and-ride or commercial centres equipped with fast recharge infrastructure will require dedicated grid connections to the HV transmission grid, due to the significant installed power. The interaction between those multi-MW scale recharge aggregates and...
Battery Energy Storage Systems (BESSs) represent an useful tool for grid support and integration of renewable energy sources. Amongst the different technologies, Lithium-Titanate batteries represent one of the most promising solutions, due to their very long expected lifetime. The paper deals with the commissioning and testing of Terna's Lithium-Titanate, 1MWh, BESS in Codrongianos substation, both...
The overall efficiency of battery electrical storage systems (BESSs) strongly depends on auxiliary loads, usually disregarded in studies concerning BESS integration in power systems. In this paper, detailed electrical-thermal battery models have been developed and implemented in order to assess a realistic evaluation of the efficiency of NaS and Li-ion batteries. BESSs have been sized in order to...
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