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In this work, we fabricated a biaxially stretchable light-emitting diode (LED) display based on a wavy structured-metal electrode grid packaged together with LED chips. The micro-electromechanical systems (MEMS) fabrication process was utilized to fabricate the wavy-structured metal connections and rigid islands. The resulting LED display can be readily bent, rolled, stretched and even washed with no degradation of its image quality. Here at least 1000 stretching cycles at a 10% strain can be tolerated. This work demonstrated the potential of inorganic materials as stretchable displays and MEMS compatible processes which can be used as stretchable electronics fabrication processes. [2022-0029] [ABSTRACT FROM AUTHOR]

In this work, a stretchable thin film capacitive strain sensor based on wavy-structured interdigitated metal electrodes is successfully demonstrated. Wavy-shape metal electrodes were patterned using bulk silicon micromachining, endowing the electrodes with high stretchability and reliability. The electrodes were also protected with a layer of parylene C to prevent damage during stretching and embedded in polydimethylsiloxane (PDMS) stretchable package layers. The interdigitated electrodes sitting on the wavy structures experienced a waving angle change under external strain resulting in capacitive change, which is the sensing mechanism of the wavy structured interdigitated capacitive strain sensor (WICSS). The sensitivity and stretchability of the WICSS is dependent on the design of interdigitated electrodes and the dimension of the wavy structures. The gauge factor (GF) of the WICSS was 0.27 at 25% strain. There was little hysteresis during the stretching and releasing process in the range of 25% strain. The sensing property remained stable within a 1000 cycling test. The applications of the high-performance WICSS are also demonstrated by detecting the motion of human fingers and wrists. [ABSTRACT FROM AUTHOR]

In the electromagnetic transient (EMT) and transient stability (TS) hybrid simulation, the entire power system is artificially split into two sub-grids, and sub-grids interact with each other via an interface. Thus interface distortions emerge, including latency and errors. The influence of interface latency is quantitated based on a demo circuit containing delayed interaction. Moreover, the principles of improving hybrid simulation interface accuracy are concluded. Inspired by the principles, a novel interface displacement (ID) and dynamic phasor mapping equivalence (DP-ME) interface scheme is proposed. The scheme makes sub-grids at opposite sides of an interface loosely coupled and avoids interface variable form conversion by applying two techniques. 1) Displacement of the partition interface from the converter buses to the control loops and interior of the EMT sub-grid to utilize the built-in inertias. 2) Construction of the DP-ME model to calculate the injected power from EMT to TS sub-grid. Tests based on designed cases and an actual HVAC/DC power grid give credibility to the proposed ID & DP-ME scheme in comparison with full electromagnetic simulation. [ABSTRACT FROM AUTHOR]

With the increasing penetration of renewable energies in modern power grids, large amounts of voltage source converters (VSCs) have been installed, resulting in many new transient issues. Electromagnetic transient (EMT) simulation plays an essential role in investigating and solving the issues. However, simulation efficiency plunges when object grids contain multiple VSCs, because each switching event incurs modification or re-decomposition of the network matrix in traditional EMT programs, which is very time-consuming. Thus, this paper proposes a VSC model represented by pulse voltage-current source pairs. Accordingly, a unidirectional loosely-coupled solving algorithm is designed. Synthetically, the authors propose a novel EMT simulation approach adaptive to systems with multiple VSCs. The proposed approach keeps the computational network invariable while sufficiently considers detailed switching events, thereby significantly improving the simulation efficiency of the EMTP program without precision loss. [ABSTRACT FROM AUTHOR]