Extended defects, including exposed surfaces and grain boundaries (GBs), are critical to the properties of polycrystalline solid electrolytes in all-solid-state batteries (ASSBs). These defects can alter the mechanical and electronic properties of solid electrolytes, with direct manifestations in the performance of ASSBs. Here, by building a library of 590 surfaces and grain boundaries of 11 relevant solid electrolytes—including halides, oxides, and sulfides— their electronic, mechanical, and thermodynamic characteristics are linked to the functional properties of polycrystalline solid electrolytes. It is found that the energy required to mechanically “separate” grain boundaries can be significantly lower than in the bulk region of materials, which can trigger preferential cracking of solid electrolyte particles in the grain boundary regions. The brittleness of ceramic solid electrolytes, inferred from the predicted low fracture toughness at the grain boundaries, contributes to their cracking under local pressure imparted by lithium (sodium) penetration in the grain boundaries. Extended defects of solid electrolytes introduce new electronic interfacial states within bandgaps of solid electrolytes. These states alter and possibly increase locally the availability of free electrons and holes in solid electrolytes. Factoring effects arising from extended defects appear crucial to explain electrochemical and mechanical observations in ASSBs. ... Read more

As the use of distributed energy resources increases, peer-to-peer (P2P) energy trading is becoming a promising way to harmonize the decarbonization and decentralization transformations in the energy sector. P2P markets give households the autonomy to make individual decisions and thus they may cooperate with each other to obtain economic benefits. However, existing studies on cooperative behaviors in P2P markets focus mostly on the electricity sector and P2P multi-energy markets are rarely studied. In fact, other energy carriers not only constitute a large part of the total energy demand, but their coupling can potentially benefit the system as well as the end-users. In this paper, we propose a P2P multi-energy market mechanism that allows peers to trade both electricity and heat. Two trading coalitions, i.e., an electricity-only trading coalition and an electricity–heat trading coalition, are predefined. The peers will join one of the coalitions based on their potential benefits and will trade energy inside the coalition. The energy markets are cleared separately per coalition and per energy carrier and hence, multi-energy markets are modeled. The proposed mechanism is a first-of-its-kind that explores the integrated effects of the multi-energy coupling and the cooperative behaviors in the P2P market. It is illustrated by a case study on a neighborhood in the Netherlands using realistic data. Results show that the mechanism is prosumer-centric as peers choose to join different coalitions at different time steps which benefit them the most. Compared to the reference scenario where there is no P2P trading, the P2P multi-energy market leads to higher economic benefits for all the peers altogether and benefits most individuals. The case study also demonstrates a benefit transfer from service-sector peers to residential peers. ... Read more

HVDC technologies are widely acknowledged as one of solutions for the interconnection of renewable energy resources with the main electric power grid. The application of the latest modular multi-level converter (MMC) makes power conversion much more efficient. Due to the relatively low impedance in a DC system, DC fault currents may rise to an extremely high level in a short period of time, which can be very dangerous for HVDC converters. To improve the sustainability and security of electricity transmission, protection solutions for HVDC systems are being developed. Nevertheless, they have various drawbacks on fault signal detection and timely clearance. This paper proposes a protection method that provides a fast and reliable solution addressing those drawbacks. A protection algorithm based on travelling wave simulation and analysis is proposed to detect abrupt transient signals. The algorithm shows high efficiency, reliability, selectivity and has low sampling frequency requirements. The proposed protection method has been validated through a cyber-physical simulation platform, developed using a real-time digital simulator (RTDS) and IEC 61850 communication links. The obtained results show that the proposed method has good potential for practical applications. ... Read more

Eddy current pulsed thermography (ECPT) is well established for nondestructive
testing of electrical conductive materials, featuring the advantages of contactless, intuitive detecting and efficient heating. The concept of divergence characterization of the damage rate of carbon fibre-reinforced plastic (CFRP)-steel structures can be extended to ECPT thermal pattern characterization. It was found in this study that the use of ECPT technology on CFRP-steel structures generated a sizeable amount of valuable information for comprehensive
material diagnostics. The relationship between divergence and transient thermal patterns can be identified and analysed by deploying mathematical models to analyse the information about fibre texture-like orientations, gaps and undulations in these multilayered materials. The developed algorithm enabled the removal of information about fibre texture and the extraction of damage features.
The model of the CFRP-glue-steel structures with damage was established using COMSOL Multiphysics® software, and quantitative non-destructive damage evaluation from the ECPT image areas was derived. The results of this proposed method illustrate that damaged areas are highly affected by available information about fibre texture.
This proposed work can be applied for detection of impact induced damage and quantitative evaluation of CFRP structures. ... Read more