Battery energy storage systems for ancillary services provision

LAUREA MAGISTRALELo scopo di questo lavoro di tesi è la simulazione del comportamento di un sistema di accumulo energetico a batteria, nella fornitura di servizi di rete nel contesto di un Mercato dei Servizi Ancillari. Gli accumuli a batteria sono al giorno d’oggi coinvolti in vari progetti pilota in tutto il mondo per la fornitura di servizi ancillari. Questo accade perché questi sistemi presentano alcune caratteristiche di interesse rispetto ai generatori elettrici tradizionali, che usualmente sono gli unici soggetti autorizzati a prendere parte al mercato dei servizi ancillari. In particolare, grazie al gradiente di potenza estremamente elevato che riescono a fornire e alla precisione nel seguire setpoint di potenza che li caratterizza, gli accumuli elettrochimici possono portare grande beneficio alla sicurezza della rete elettrica odierna, che affronta l’integrazione di Fonti Energetiche Rinnovabili non programmabili e aleatorie. La metodologia proposta è la simulazione della fornitura di molteplici servizi di rete su un periodo di 30 giorni, utilizzando un modello elettrico ed uno empirico per una cella agli ioni di litio implementati in Simulink. Il lavoro comprende lo sviluppo del controllore del modello, l’analisi e lo sviluppo di una procedura completa e replicabile per la rappresentazione accurata di servizi di rete, la validazione del modello empirico e la simulazione di varie combinazioni di fornitura di servizi, ossia di differenti schemi per la Regolazione Primaria e Secondaria di Frequenza. I risultati delle simulazioni sono stati esaminati ed elaborati dal punto di vista della certezza della fornitura (punto di vista dell’operatore della rete di trasmissione dell’energia) e del ritorno economico (punto di vista dell’investitore). Le simulazioni hanno mostrato notevoli prestazioni del sistema di accumulo nella fornitura del servizio richiesto. Nel caso studio migliore, la potenza non fornita è stata meno del 2% sul totale della potenza richiesta. Questo risultato è stato raggiunto sfruttando le caratteristiche favorevoli della fornitura di Riserva Secondaria in maniera asimmetrica. Dal punto di vista del ritorno economico, analizzando il caso del Mercato dei Servizi di Dispacciamento (MSD) italiano, i risultati hanno mostrato un tempo di ritorno di almeno 12 anni. Nello studio del contesto tedesco invece, il tempo di ritorno scende a 3 anni.The scope of this work is simulating behavior of a Battery Energy Storage System (BESS) providing grid services in the context of an Ancillary Services Market (ASM). BESS are nowadays involved in several pilot projects for Ancillary services provision around the world. This is because they have some characteristics of interest with respect to conventional power generators that are usually the only providers trading on ASM. Specifically, the extremely high ramp rate and the precision in following power setpoints can provide extreme benefit for security of today’s power network, facing the integration of non-programmable and unpredictable Renewable Energy Sources (RES). The methodology proposed is the simulation of provision of multiple services on a 30-days period using an electric and an empirical Li-ion battery model implemented in a Simulink tool. The work included the development of the controller of the model, the analysis and the development of a complete and replicable procedure for accurate representation of grid services, the validation of the empirical cell model and the simulation of different combination of services provision, namely different layouts of Primary and Secondary Control Regulation. Results of the simulations were investigated and elaborated by both the points of view of the assurance of provision (the point of view of the Transmission System Operator) and of the economic return (the point of view of the investor). Simulations showed outstanding performance by BESS in providing the power requested. In the best case, power non-provided was less than 2% of the overall power requested. This result was achieved by exploiting the favorable characteristics of asymmetric Secondary Reserve provision. By the side of economic return, when inspecting the Italian ASM framework, results showed Payback Time (PBT) of at least 12 years. When analyzing German framework, PBT decreased to 3 years

Abate the barriers : opening electricity markets to storage and RES

DOTTORATOIl lavoro di tesi presentato considera i mercati elettrici in presenza di Battery Energy Storage Systems (BESS), fonti di energia rinnovabile (FER) e Generazione Distribuita (GD). Mira a fornire una visione panoramica delle possibili evoluzioni regolatorie dei mercati elettrici, con particolare attenzione ai Mercati per il Servizio di Dispacciamento (MSD). Viene riportato lo stato dell’arte dei MSD e del bilanciamento elettrico, con particolare attenzione ai prodotti di bilanciamento standard per il controllo della frequenza. Vengono descritti i principali attori dei MSD: il gestore del servizio (ad esempio, l’operatore della rete di trasmissione) e il Balancing Services Provider (BSP). Viene eseguita una meta-analisi delle fonti per valutare i possibili trade-off nell’evoluzione del MSD, considerando sia la prospettiva dell’operatore, sia quella del BSP. L'analisi restituisce qualitativamente la compatibilità del quadro del MSD con la GD e i BESS e rileva le possibili barriere regolatorie per la loro effettiva partecipazione. Per valutare quantitativamente le prestazioni dei BESS nella fornitura di servizi ancillari, viene sviluppato un modello numerico di BESS. Questo ha lo scopo di superare una serie di carenze riscontrate nei modelli di batteria presenti in letteratura, che li rende inadatti ad essere utilizzati per testare la partecipazione al MSD. Il modello è un modello empirico multi-parametro basato su una campagna sperimentale su un sistema reale industriale. I parametri del modello restituiscono le prestazioni complessive del sistema, incluso l'impatto del sistema di conversione di potenza e dei sistemi ausiliari. Viene valutata l'influenza del contenuto energetico finito dei BESS sulla fornitura di servizi ancillari. Viene evidenziata l’importanza delle strategie di gestione del contenuto energetico, proponendo un'analisi comparativa tra le strategie di gestione dello stato di carica o state-of-charge (SoC). Le strategie analizzate sono definite “esplicite” in quanto considerano flussi aggiuntivi di energia scambiati con la rete con lo scopo esplicito di ripristinare il SoC. Le limitazioni delle strategie di gestione esplicita del SoC aumentano l'interesse per strategie “implicite”. Viene sviluppata una strategia Multiservizio per fornire la gestione del SoC con un servizio di mercato aggiuntivo (e remunerato). La strategia Multiservizio sfrutta lo stacking dinamico dei servizi e garantisce lo stacking delle entrate. Viene proposta e valutata su due casi studio. Poi, la strategia implicita di gestione del SoC basata sul Multiservizio è confrontata con quelle esplicite. Il modello BESS e l'analisi precedentemente presentata sull'evoluzione del MSD sono utilizzati per stimare gli assetti ottimali del MSD per la fornitura di servizi da parte di BESS. Due diversi servizi sono testati insieme a una serie di parametri del MSD, riconosciuti come potenziali barriere regolatorie. Gli assetti del MSD sono valutati in termini di flessibilità che può essere fornita dalle risorse e di affidabilità della fornitura. Vengono restituiti i valori ottimali dei parametri del MSD per i vari tipi di servizi. Infine, per verificare se la partecipazione dei BESS al bilanciamento elettrico porta vantaggi al sistema, la fornitura della risposta in frequenza da parte dei BESS viene testata con uno strumento di analisi di power flow. Vengono eseguite simulazioni dinamiche della rete e i risultati sono valutati in termini di qualità del servizio (cioè il nadir di frequenza dopo un incidente) e le esigenze del sistema (cioè la potenza regolante necessaria) in caso di regolazione della frequenza da parte di centrali termiche convenzionali o di BESS.The presented Thesis work considers the electricity markets in the presence of Battery Energy Storage Systems (BESS), Renewable Energy Sources (RES) and Distributed Energy Resources (DERs). It aims to provide a panoramic view of the possible regulatory evolutions of electricity markets, with particular focus on the Ancillary Services Markets (ASMs). The state-of-the-art of ASM and of the electricity balancing is reported, with focus on the standard balancing products for frequency control. The main stakeholders of the ASM are described: the System Operator (SO) and the Balancing Services Provider (BSP). A systematic review of sources is performed to assess the possible trade-offs in the ASM evolution, considering both the perspective of the SO and the BSP. The analysis qualitatively returns the compatibility of the ASM framework with DERs and BESS and detects the possible regulatory barriers for their effective participation. To quantitatively assess the performance of BESS in the provision of ancillary services, a numerical model of BESS is developed. This is aimed to overcome a set of lacks found in the battery models present in literature, that makes them unsuitable to be used for testing ASM participation. The model is a multi-parameter empirical model based on an experimental campaign on a real-world asset. The model parameters return the overall performance of the system, included the impact of the power conversion system and of auxiliary systems. The influence of the finite energy content of BESS on the provision of ancillary services is assessed. The importance of strategies for managing the energy content is highlighted, by proposing a comparative analysis among state-of-charge (SoC) management strategies. The analyzed strategies are defined “explicit” since they consider additional energy flows exchanged with the grid with the explicit purpose of restoring the SoC. The limitations of the explicit SoC management strategies enhance the interest for “implicit” strategies. A Multiservice Strategy is developed for providing SoC management via an additional (and remunerated) market service. The Multiservice Strategy exploits dynamic service stacking and guarantees revenue stacking. It is proposed and evaluated on two case studies. Then, the implicit SoC management strategy based on Multiservice is compared with the explicit ones. The BESS model and the previously presented analysis on the evolution of ASM are used to estimate the optimal ASM arrangements for the provision of services by BESS. Two different services are tested along with a set of ASM parameters, recognized as potential regulatory barriers. The ASM arrangements are evaluated in terms of the flexibility that can be provided by the resources and the reliability of the provision. The optimal values of the ASM parameters for each type of service are returned. Finally, to check if the BESS participation in electricity balancing brings advantages to the system, the provision of frequency response by BESS is tested with a power flow analysis tool. Dynamic simulations are performed and the results are appraised in terms of quality of service (i.e., frequency nadir after an incident) and system needs (i.e., needed regulating power) in case of frequency regulation by either conventional thermal power plants or BESS.DIPARTIMENTO DI ENERGIA34MERLO, MARCOMUSSETTA, MARC

Tariff-based regulatory sandboxes for EV smart charging: Impacts on the tariff and the power system in a national framework

Electrification of private transport is a fundamental step for decarbonizing mobility. Electric vehicles (EV) can be a burden for the power system if vehicle-grid integration is not implemented by design. Market-based smart charging projects are effective, but their massive diffusion is limited. A fundamental instrument toward a large adoption of smart charging is the inclusion of smart charging-oriented measures in regulatory sandboxes, conveniently acting on electricity tariff. This paper presents a set of possible toolboxes for smart charging to show the potential that regulatory measures can have on steering the infrastructure deployment and the charging activity. Each proposed toolbox addresses a specific charging mode, including domestic, workplace, and public access charging. Proposed measures are target-oriented and evaluated based on their environmental, technical, and economic impacts. These include the carbon footprint of the electricity used for EV charging, the impact in terms of peak power withdrawal from the public grid and the charging cost born by EV users. Additionally, the assessment about the impact of prospected measures on the electricity tariffs' income is provided. Results show the possibility of reducing the evening EV-related peak load by 30% to 50% via home smart charging. Also, a 10% decrease in carbon footprint is achieved by valley-filling with work charging. Charging at the destination can reduce the system cost for the new distribution infrastructure, dropping the number of new dedicated connection points for public charging. The cost of incentives is partially repayable considering the additional EV penetration fostered by the reduced charging costs

Battery Energy Storage System Performance in Providing Various Electricity Market Services

The Battery Energy Storage System (BESS) is one of the possible solutions to overcoming the non-programmability associated with these energy sources. The capabilities of BESSs to store a consistent amount of energy and to behave as a load by releasing it ensures an essential source of flexibility to the power system. Nevertheless, BESSs have some drawbacks that pose limitations to their utilization. Indeed, effectively managing the stored and released energy is crucial, considering the degradation of performance associated with these systems over time. The substantial capital expenditure (CAPEX) required to install these systems represents a current constraint, impeding their broader adoption. This work evaluates a techno-economic analysis of a 2MW/2MWh BESS providing multiple services, namely participating in capacity and balance markets. The analysis is based on a BESS model implemented in SIMULINK, adopting online data gathered from a Lithium Iron Phosphate (LFP) battery facility. The model evaluates the auxiliary power consumption, state-of-charge (SoC), state of health (SoH), and the round-trip efficiency (RTE) of the overall system. The analysis is based on three price profiles: 2019 (Business-As-Usual), 2020 (COVID-19), and 2022 (Gas Crisis). Furthermore, this work conducts a case study to analyze the behavior of the BESS. It entails a sensitivity analysis, specifically evaluating the influence of CAPEX and upward bid price on the economic viability of the project. The results show a strong relation between the CAPEX variation and the Internal Rate of Return (IRR) of the project

Unlocking Grid Flexibility: Leveraging Mobility Patterns for Electric Vehicle Integration in Ancillary Services

The electrification of mobility has introduced considerable challenges to distribution networks due to varying demand patterns in both time and location. This underscores the need for adaptable tools to support strategic investments, grid reinforcement, and infrastructure deployment. In this context, the present study employs real-world datasets to propose a comprehensive spatial–temporal energy model that integrates a traffic model and geo-referenced data to realistically evaluate the flexibility potential embedded in the light-duty transportation sector for a given study region. The methodology involves assessing traffic patterns, evaluating the grid impact of EV charging processes, and extending the analysis to flexibility services, particularly in providing primary and tertiary reserves. The analysis is geographically confined to the Lombardy region in Italy, relying on a national survey of 8.2 million trips on a typical day. Given a target EV penetration equal to 2.5%, corresponding to approximately 200,000 EVs in the region, flexibility bands for both services are calculated and economically evaluated. Within the modeled framework, power-intensive services demonstrated significant economic value, constituting over 80% of the entire potential revenues. Considering European markets, the average marginal benefit for each EV owner is in the order of 10 € per year, but revenues could be higher for sub-classes of users better fitting the network needs