A SYSTEM FOR STATE-OF-HEALTH DIAGNOSIS OF LEAD-ACID BATTERIES INTEGRATED WITH A BATTERY CHARGER Telles B. Lazzarin1 and Ivo Barbi2 1Federal Institute of Santa Catarina (IFSC), Florianópolis - SC, Brazil 2Federal University of Santa Catarina (UFSC), Florianópolis - SC, Brazil

 

A SYSTEM FOR STATE-OF-HEALTH DIAGNOSIS OF LEAD-ACID BATTERIES INTEGRATED WITH A BATTERY CHARGER 

Author Telles B. Lazzarin1 and Ivo Barbi

 Abstract – This paper reports a theoretical and experimental study on a proposal for a lead–acid battery charger applied in UPS, which has an integrated on-line test system to determine the state-of-health (SoH) of the batteries. The charger control structure is designed to ensure an appropriate charge for every battery in the pack. The battery evaluation system is based on historical analysis of the periodic measurements, such as internal impedance, DC voltage and operation temperature, performed for each battery. The periodic monitoring of these parameters provided by the integration of systems eliminates the disadvantages of online tests and thus allows the user to analyze the batteries adequately. The structure was experimentally verified on a prototype, where the battery SoH diagnosis system was integrated with a 1.5 kW battery charger. The system was designed for a bank of sixteen batteries associated in series.

LINK : https://journal.sobraep.org.br/index.php/rep/article/view/398/358

Comparative fire hazards of lithium-ion battery chemistries: Linking thermal behavior, gas toxicity, and state-of-charge to composite risk profiles Aamir Iqbal , Ashish Kakoria , Syed Talha Riaz , Jingmin Xu , Robert Illango Pushparaj , Guang Xu * Department of Mining and Explosives Engineering, Missouri University of Science and Technology, Rolla, MO, 65401, USA

 

ABSTRACT 

Lithium-ion batteries (LIB) are widely used in electric vehicles (EVs) for their high energy density. However, their fire safety causes concerns because of the toxic gases emission and the challenge to extinguish. The type and quantity of toxic gases released during battery fires remain among the least studied hazards, with limited data available despite their serious health risks. This study examines the thermal and gaseous emission behavior of LIB cells after thermal runaway (TR). Five cell types, Lithium Iron Phosphate (LFP), Lithium Titanate (LTO), and three Lithium Nickel Manganese Cobalt oxide (NMC). The three NMC variants share the same base formula (LiNiMnCoO2); NMC1 and NMC3 differ only by manufacturer, while NMC2 has added Ni and Co for enhanced performance. These cells were tested under controlled thermal abuse conditions using a Ni-Chrom resistance wire powered by a DC voltage regulator. Tests were conducted at five states of charge (0 %, 25 %, 50 %, 75 %, 100 % SOC). Temperature profiles and fire/explosion observations were recorded along with the ten types of gas release rates including Carbon Monoxide (CO), Methane (CH4), Carbon Dioxide (CO2), Ammonia (NH3), Ethene (C2H4), Propene(C3H6), Formaldehyde (CH2O), Acrolein (C3H4O), Hydrogen Cyanide (HCN) and Hydrogen Fluoride (HF). CO showed the highest levels of toxic emissions reaching 150–200 L/kWh. Peak emission rates were highest for CO2 across all chemistries. A quantitative risk assessment was performed by combining the measured factors into a risk index (RI). These data were visualized in a color-coded heat map, allowing comparison of overall hazard across chemistries and charge levels. Key contributions include the first systematic measurement of formaldehyde emissions during LIB fires and the introduction of a cell-level safety rating, an actionable safety tool. This study contributes to the understanding of gas emissions during LIB fire, and evaluates the risks related to the types of battery and SOC. 

 LINK:https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3000&context=min_nuceng_facwork

Les nouvelles stratégies de contrôle d’onduleurs pour un système électrique 100% interfacé par électronique de puissance by Guillaume Denis-

 From grid-following to grid-forming: The new strategy to build 100 % power-electronics interfaced transmission system with enhanced transient behavior Les nouvelles stratégies de contrôle d’onduleurs pour un système électrique 100% interfacé par électronique de puissance 

 Thèse présentée en vue d’obtenir le grade de Docteur En Spécialité: Génie Électrique Par Guillaume Denis Doctorat délivré par Centrale Lille Résumé In the context of renewable energy and HVDC links development in power systems, the present work concerns the technical operations of such systems. As wind power, solar photovoltaics and HVDC links are interfaced to the transmission grid with power-electronics, can the system be operated in the extreme case where the load is fed only through static converters?Driving a power system only based on power electronic interfaced generation is a tremendous change of the power system paradigm that must be clearly understood by transmission grid operators. The traditional “grid-feeding” control strategy of inverters exhibits a stability limit when their proportion becomes too important. The inverter control strategy must be turned into a “parallel grid-forming” strategy.This thesis first analyses the power system needs, proposes the requirements for “parallel grid-forming” converters and describes the associated challenges. Accordingly, the thesis gives a method for designing a stable autonomous synchronization controls so that grid-forming sources can operate in parallel with a good level of reliability. Then, a method is proposed to design a voltage control for a grid-forming PWM source taking into account the limited dynamic of large converters. The robustness of the solution is discussed for different configuration of the grid topology. A current limiting strategy is presented to solve the current sensitivity issue of grid-forming converters, subject to different stressing events of the transmission grid. The ideas developed on a single converter are then applied on small grids with a limited number of converters to allow a physical interpretation on the simulation results.

VIEW FULL THESIS: https://hal.science/tel-01905827v1

Direct AC Voltage Control for Grid-Forming Inverters Taoufik Qorai , Chuanyue Li , Ko Oue , Francois Gruson , Fréderic Colas , Xavier Guillaud

Direct AC Voltage Control for Grid-Forming Inverters Taoufik Qorai (1) , Chuanyue Li (1) , Ko Oue (1) , Francois Gruson (1) , Fréderic Colas (1) , Xavier Guillaud (1) 

 Résumé 

 Grid-forming inverters usually use inner cascaded controllers to regulate output AC voltage and converter output current. However, at the power transmission system level where the power inverter bandwidth is limited, i.e., low switching frequency, it is difcult to tune controller parameters to achieve the desired performances because of control loop interactions. In this paper, a direct AC voltage control-based state-feedback control is applied. Its control gains are tuned using a linear quadratic regulator. In addition, a sensitivity analysis is proposed to choose the right cost factors that allow the system to achieve the imposed specifcations. Conventionally, a system based on direct AC voltage control has no restriction on the inverter current. Hence, in this paper, a threshold virtual impedance has been added to the state-feedback control in order to protect the inverter against overcurrent. The robustness of the proposed control is assessed for diferent short-circuit ratios using smallsignal stability analysis. Then, it is checked in diferent grid topologies using time domain simulations. An experimental test bench is developed in order to validate the proposed control.

FUL PAPER: https://hal.science/hal-02458108v1

Resilient microgrids with high dynamic stability in the presence of massive integration of variable renewables BY Kevin Banjar Nahor -THÈSE Pour obtenir le grade de DOCTEUR DE LA COMMUNAUTE UNIVERSITE GRENOBLE ALPES Spécialité : Génie Electrique

 

Resilient microgrids with high dynamic stability in the presence of massive integration of variable renewables Kevin Banjar Nahor 

Abstract This thesis deals with the stability issues introduced by the interconnection of massive renewables into an isolated microgrid. This research aims to identify the problems related to the topic, the indices to help understand the issues, and the strategy to enhance microgrid stability from the power system point of view.In the first part, a state of the art on the evolution of power stability is addressed. A short history of power system stability since its first identification and how it has evolved is firstly presented. This part also provides a literature review of the power system stability, including its classification, and how it has evolved due to two reasons: the microgrid concept and the trend towards the integration of more inverter-based generation. A review of the practical indices for grid stability assessment is also reported, including the ones that we propose. This part is also useful for analyzing the positioning of this PhD research.The second part of thesis presents the efforts to enhance the dynamic stability of microgrids characterized by massive renewable penetration. The main challenges and the current efforts are reviewed, which have shown that the current solutions focus on maintaining the philosophy of a classical power grid. With the advent of more intermittent energy, the current efforts have proven to be costly. Therefore, a new perspective is proposed. Here, the generating elements and the customers are exposed with higher deviations in voltage and frequency, which are necessary so that that the power equilibrium and the stability of the microgrid can be maintained. This perspective is suitable with the microgrid concept to realize the dream of universal electricity.The concept is then developed into a novel regulation strategy in which the system frequency and voltage are maintained in such a way to keep their ratio essentially constant around 1 (p.u. voltage to p.u. frequency). This strategy can potentially be implemented on all grid forming technologies. The benefits of employing this strategy include assurance that the electrical machinery is not harmed, plug-and-play feature, compatibility with current grid-tied inverter technologies, and no need for fast communication systems. Finally, this proposed strategy is easy to implement and does not require revolution in terms of power system equipment and control. This implementation of this concept provides a very valuable piece of flexibility: time, which enhances the resilience and stability of a microgrid. However, wider frequency and voltage deviations occur and have to be accepted by all the actors within the microgrid. A validation through computer simulations in Power Factory and real-time hardware in the loop experiments has been carried out with satisfactory results.

LINK FULL THESIS: https://hal.science/tel-03042626v1