LCL filters are commonly used to connect Voltage Sourced Converters (VSCs) to the grid. This type of filter is cheaper than a single inductor for the same current THD, but it generates resonance problems if no active or passive damping method is applied. Active damping methods are becoming popular in the literature because they improve efficiency, but they are sometimes difficult to implement and additional measurements are required. This paper proposes an active damping method for VSCs connected to weak grids that is based on making zero the open-loop phase at the resonance frequency. It will be shown that this strategy provides adequate damping of oscillations and that it can be achieved in two different ways: at the design stage (if the design constraints make it possible) or with an all-pass filter in series with the current controller. Two methods to design the all-pass filter are proposed. Also, the proposed active damping technique is compared with three alternatives already proposed in the literature. All the control algorithms are verified by simulation and in a 15 kW prototype of a three-phase VSC connected to a configurable weak grid via a LCL filter.

Distribution systems have traditionally received the least attention in the bulk picture of power systems; they are yet the most "critical component" as they directly impact customers’ perception and utilities’ reputation. While transmission systems have seen abundant literature, innovations, and applications of power electronic-based devices to optimize their performance, distribution systems still require more attention toward a flexible and dynamic scheme to cope with volatile energy consumption and production. As a replacement or enhancement of the traditional ones, Solid-State Transformers can play a central role in the energy management of distribution systems towards this goal, in addition to the mere voltage conversion. This manuscript, developed within the IEEE Task Force on Solid-State Transformer integration in distribution grids, offers a critical review of the Solid-State Transformer potential, services, and technical challenges for its integration in distribution systems. Particular attention is given to scientific trends and open points in the current research that must be addressed before utilities extensively integrate the Solid-State Transformer in distribution systems.

LCL-filter-based grid-tie inverters require damping for the current-loop stability. There are only software modifications in active damping, whereas resistors are added in passive damping. Although passive damping incurs in additional losses, it is widely used because of its simplicity. This paper considers the active damping in medium-voltage parallel inverters for wind turbines. Due to cost reasons, only minimal software changes are allowed and no extra sensors can be used. The procedure must be robust against line-inductance variations in weak grids. Double-update mode is needed so the resonance frequency is under the Nyquist limit. The bandwidth reduction when using active damping is also required to be known beforehand. Moreover, the design procedure should be simple without requiring numerous trial-and-error iterations. In spite of the abundant literature, the options are limited under these circumstances. Filter-based solutions are appropriate and a new procedure for tuning the notch filter is proposed. However, this procedure requires that the resistance of the inductors is known and a novel filter-based solution is proposed that uses lag filters. The lag filters displace the phase angle at the resonance frequency so that the Nyquist stability criterion is fulfilled. Simulations and experiments with a 100-kVA prototype validate the analysis.

The stability and accuracy of power hardware-in-the-loop (PHIL) setups are sensitive to and deteriorated by the dynamics and nonideal characteristics of their power interfaces, such as time delay, noise perturbation, and signal distortion. In this article, a compensation scheme comprising a Smith predictor compensator is proposed to mitigate the impact of time delay on PHIL stability. Furthermore, an online system impedance identification technique is leveraged to enhance the robustness of the compensator and facilitate the compensation scheme with adaptivity to system impedance variation. Analytical assessment, simulation results, and PHIL experimental results are presented to verify the proposed compensation scheme. This scheme enables robust and stable testing of novel power technologies under varying impedance ratios representative of the complex scenarios emerging within the power sector.

This article reviews various inductive and capacitive wireless charging systems to achieve high-power infrastructures. The characteristics of SAE, ICINRP, and IEEE safety standards for wireless charging technology were highlighted. The working of compensation circuits, resonant converters, and challenges in wireless power transfer (WPT) systems was discussed. The mechanism of different compensation circuits used in the WPT was discussed in detail. In addition, the design of the converter circuit topology of inductive and capacitive power transfer systems in electric vehicle (EV) batteries was highlighted. The foreign object detection (FOD) methods that prevent output power variations due to metal/living objects in the charging environment were explored. The foreign object detection (FOD) techniques in terms of impedance variations in the primary side of the charging circuit were explained. This review on EVs would help researchers and industrialists to identify and develop novel charging infrastructure with low cost and charging time.

To tackle emissions from the aviation industry and make it sustainable, research has been targeting electrifying aircraft. For this aim, articles have been focusing on how to replace regular jet engines with liquid hydrogen as fuel. This would be beneficial as hydrogen is expected to play a dual role, providing fuel for fuel cells to propel the aircraft electrically and to supply cooling to enable high-power density technologies such as superconducting machines and cryogenic power electronics circuits. However, using higher power density, especially cryogenic power electronics, can be challenging. This article investigates cryogenic power electronics for use on all-electric aircraft across different aspects, where it lays out how to integrate power electronics at cryogenic temperature into the architecture of the all-electric aircraft, how to use them with hydrogen fuel cells, and the voltage levels of the system. It reviews different semiconductor device technologies, circuit topologies, and passive devices to be used in power electronics circuitry, as well as logic circuits that are suitable for use at cryogenic temperatures. In addition, the article discusses the challenges of using semiconductor devices at such low temperatures, including the reliability, overall cooling, and recycling of hydrogen.