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Timber buildings have been preferred in many regions for the sustainable nature of timber material. Although engineered timber products become promising alternates to traditional construction materials, the fire safety of timber buildings remains a key barrier to wider use. Currently, the design of timber structures mostly adopts the Eurocode 5 approach, which estimates the heat transfer or char depth under the premise of standard fire exposure. To investigate the behaviour of timber structural members in the context of realistic fire action in compartments, appropriate models for different stages of numerical simulation are needed. A series of development have now been conducted in the open‐source platform OpenSees, which enables modelling the heat transfer of timber sections in non‐standard fire scenarios and thermo‐mechanical analysis model using either beam elements or shell elements for various timber structural members. Corresponding thermal actions are developed to deal with timber slabs in fire or timber beams subjected to three‐side fire exposure. Tests on cross‐laminated timber beams at ambient temperature and under fire exposure are modelled to validate the developed capabilities, which is followed by modelling a glued laminated timber beam heated by furnace. In the end, a timber‐concrete composite slab is modelled using the fire impact from a Computational Fluid Dynamics model, which demonstrates the current vision of modelling timber structures in fire and OpenSees for fire is committed to providing such an open‐source research platform to support further modelling work. [ABSTRACT FROM AUTHOR]

Recently, renewable distributed generation (DG) systems have emerged to improve the power system security and reliability while reducing the environmental incompatibility of fossil fuel power plants. DG could operate either as a standalone and/or as a grid‐connected power system. The interfacing circuits of DG and their controls have to comply with utility quality regulations and afford a seamless transition from online to offline and vice versa. This article advises a simple and robust control scheme for a modular multilevel converter (MMC) that interfaces with a photovoltaic (PV) generator. The proposed control method ensures high‐quality output voltage/current waveform in online and/or offline operating modes. Moreover, the proposed control provides a seamless and swift transition from standalone to grid‐connected and vice versa. The exhibited control scheme is simulated with MATLAB/Simulink. Real‐time simulator OPAL‐RT OP4510 is used to verify the displayed simulation results. The simulation results determine the accomplishment of the proposed control technique for a seamless transition from the grid‐connected mode to the standalone mode and vice versa via MMC. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes three‐phase microinverter able to process the power of three PV modules simultaneously and independently; thus, efficient utilization of PV modules through distributed maximum power point tracking (DMPPT) is realized. The proposed microinverter employs switched capacitors (SCs) networks combined with three‐phase voltage source inverter; it is named switched capacitor buck‐boost voltage source inverter and abbreviated as SC‐BBVSI. The connections of SCs networks are determined to fulfill the high boosting gain along with minimized leakage currents. In addition, low capacitances values can be employed for power decoupling purpose. Thus, in addition to DMPPT feature, three features of high boosting gain, high‐reliable product, and minimized leakage current are realized without using the bulky and costly isolation transformer. In this paper, the operation modes of SC‐BBVSI for single and multi‐input scenarios are explained. The modulation strategy to realize these modes along with the control system design is presented as well. The relations required to design the passive elements and identify the device's stresses are derived. The features of the proposed microinverter are confirmed through detailed comparison with other recently reported topologies. Both simulation and experimental results are provided to verify the features of the proposed topology. [ABSTRACT FROM AUTHOR]

Inertia-less power converters are one of the main obstructions to increase the penetration level of distributed energy resources in the utility grid. The stability of the power system mainly depends on the system inertia. Virtual synchronous machine and synchronverter-based grid-tied inverters have been introduced as a solution to this problem. Here, a modified selfsynchronised synchronverter is introduced to enhance the dynamic response of the active power loop and to limit the injected active/reactive power to the grid. Furthermore, the injected current to the grid is limited during faults employing proportional-resonant-based inner current loop. Feed-forward voltage is implemented in the current control loop to achieve seamless transfer between standalone and grid-connection modes of operation. Extensive simulation and experimental results are obtained to verify the proposed enhanced controller. [ABSTRACT FROM AUTHOR]

This study proposes a new two-stage high voltage gain boost grid-connected inverter for AC-module photovoltaic (PV) system. The proposed system consists of a high-voltage gain switched inductor boost inverter cascaded with a current shaping (CS) circuit followed by an H-bridge inverter as a folded circuit and its switches operate at line frequency. The switched inductor boost converter (SIBC) has one switch operates like a continuous conduction mode. The maximum power of the PV module is achieved through the SIBC circuit whereas the grid connection requirements are accomplished using the CS circuit with the H-bridge inverter. The switch of the CS circuit is controlled with a sine wave modulation control scheme. The main advantages of the new proposed system are high boosting gain, lower switching losses and reduces the ground leakage current as all H-bridge switches operate at the line frequency. A 120 W prototype has been built and experimentally tested. It has been found that experimental results have a good matching with the proposed analysis and simulation results. [ABSTRACT FROM AUTHOR]