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A micro-grid system based on a source dual active bridge (DAB) converter connected with load buck-boost DC/DC converter and DC/AC converter by the common DC-link is studied in this paper, which is widely investigated in the yield of intelligent distribution microgrid. As the power transmission hub, the stability of the DC-link voltage plays a key role in the normal operation of the whole system, w...Show More
Breakthroughs in power electronics devices enabled the utilization of the IGBT as the main power switch in AFE converters and enabled the emergence of the fully controlled Active Front End, “AFE”, and low input harmonic solution. This solution employs voltage and current control loops and switching with relatively high switching frequencies of greater than 2 KHz in most applications. The AFE conve...Show More
This paper describes and demonstrates novel monolithic microwave ICs (MMICs) that are suitable for an integrated spectrum analyzer (SA) front end. The proposed MMICs; an up-converter, a down-converter and an active LC filter provide an ultra-wideband performance of 1-32 GHz to the front end as well as remarkable size reduction. These are the results of effective utilization of active signal combin...Show More
The impedance-based stability criterion has been established as an important tool to assess interactions of power converters with each other and the electrical grid. The converter impedance is strongly influenced by the converter control system, which can include a variety of parameters. This is especially relevant for converters connected to the grid using LCL filters. Additionally, higher switch...Show More
Fuel cell systems appear as a good alternative for future power generation. This is mainly due to their high energy conversion efficiency and simple operation. Since the output of the fuel cell is low voltage DC, fuel cell systems supplying power to AC loads are usually constructed using a two stage approach cascading a DC-DC converter and an inverter. It can be shown that in such a system the cur...Show More
The virtual impedance concept is increasingly used for the control of power electronic systems. Generally, the virtual impedance loop can either be embedded as an additional degree of freedom for active stabilization and disturbance rejection, or be employed as a command reference generator for the converters to provide ancillary services. This paper presents an overview of the virtual-impedance-b...Show More
This paper analyzes the low frequency stability chal-lenges that exist in a generic DC microgrid system. The conditions for system stability are derived from fundamental principles. A capacitive energy storage system based active voltage stabilizer, that handles the power fluctuations within the system during transient conditions, is proposed to stabilize the DC microgrid. The functionality of the...Show More
This letter presents the integration of multiple active devices output port directly with the antenna for simultaneous active frequency multiplication and radiation. This eliminates the circuitry losses at the multiplied output frequency, which points to a significant advantage of the proposed unified integration space in addition to size reduction. Furthermore, active devices are configured in pa...Show More
This paper proposes an adaptive active damping control method for the power conversion system (PCS) to address the issue of sub-/super-synchronous oscillations caused by the connection of drive permanent magnet synchronous generator (PMSG) grid-connected systems to weak grids. Firstly, the impedance model of the PMSG grid-connected system with a power conversion system is established and the imped...Show More
This paper analyzes the harmonic instability due to interactions among power converters and negative incremental impedance of load converters in a dual active bridge (DAB) converter enabled DC microgrid. Based on derived system impedances, it is found that the challenge of a DAB converter enabled microgrid stability is low frequency terminal behaviors of integrated units, which is different from o...Show More
For the photovoltaic (PV)-energy storage system, the dc-link oscillation is usually generated due to the interactions between converters. This paper takes the dual-active bridge (DAB) converter integrating energy storage as the research object of the suppression. Based on the small-signal model of DAB converter, an active damping using capacitance voltage feedforward is proposed to simulate resist...Show More
Pulse-width-modulated (PWM) voltage-source converters (VSCs) are gaining widespread acceptance in modern power systems. It has been shown recently that full-scale high-power PWM VSCs can induce negative electrical damping at subsynchronous frequencies. However, active reshaping of the VSC incremental output impedance to minimize the negative impacts of a VSC on subsynchronous damping is not report...Show More
This paper focuses on the implementation of a three-phase four wire current-controlled voltage source inverter (CC-VSI) as both power quality improvement and PV energy extraction. For power quality improvement, the CC-VSI works as a grid current-controller shunt active power filter. Then, the PV array supported by the hill climbing type of a MPPT controller is coupled to the DC bus of the CC-VSI. ...Show More
In this paper, a generalized closed-loop control (GCC) scheme is proposed for voltage source converters (VSCs) with LC or LCL output filters. The proposed GCC scheme has a single-loop control of inverter output (voltage or current) and two parallel virtual impedance terms using additional measurements. The virtual impedance can be the equivalent internal impedance or external impedance (or both), ...Show More
We report a low conversion loss and high local oscillator (LO)-to-RF isolation 94-GHz monolithic-microwave integrated-circuit (MMIC) active down converter using 0.1-/spl mu/m InGaAs/InAlAs/GaAs metamorphic high electron-mobility transistor (MHEMT). The fabricated MMIC active down converter employs a one-stage MHEMT amplifier in the RF port of the active down converter, thereby amplifying the RF si...Show More
This article investigates using imbalanced two- and three-wire terminations for ac main cables, as suggested by the standard group. These terminations provide the basis for a new line impedance stabilization network (LISN) whose objective is to improve test repeatability between labs while also providing better estimation of real-world emissions. Standard balanced LISNs do not reproduce the imbala...Show More
Conducted electromagnetic interference (EMI) has been a major concern in designing power converters, requiring additional filtering components. Passive EMI filters, which are composed of inductors and capacitors, usually occupy a great portion of the volume and weight in power converters. Active EMI filters (AEF) or hybrid EMI filters (HEF) are best candidates over traditional passive EMI filters ...Show More
The sensitivity analysis of a circuit reflects the robustness of this circuit to the relevant parameters. This paper investigates the sensitivity of input impedance of DAB converter, which is widely adopted in solid-state transformer (SST) and dc microgrid on more electric aircraft (MEA). In this paper, an improved impedance-based small-signal averaged model is developed to carry out the sensitivi...Show More
This paper derives the closed-loop impedance model for the typical three-phase active rectifier and investigates the dominant factors influencing the converter impedance below 150 kHz frequency range from the basic performance (e.g., steady-state and dynamic performance) and EMI perspectives. Therefore, the complete modeling process of the closed-loop impedance is described, including the control ...Show More
The penetration of the distributed power generation systems (DPGSs) based on renewable sources (PV, WT) is strongly dependent on the quality of the power injected to the utility grid. However, the grid impedance variation, mainly caused by grid faults somewhere in the electric network, can degrade the power quality and even damage some sensitive loads connected at the point of the common coupling ...Show More
Multistage systems are highly prone to issues of instability due to the interaction between converters. In this paper, the operation principles of a novel triple-phase-shift based dual active bridge converter are elaborated. Additionally, the impedance model of the cascaded system based on small signal analysis is proposed and applied for analyzing the stability of the cascaded system. The theoret...Show More
In this paper, the small signal stability issue of a dual-active-bridge (DAB) converter enabled dc microgrid is addressed. The derived impedance characteristic of the source DAB converter reveal that the stability of this dc grid is decided by the low-frequency terminal behaviors of integrated units, which is different from that of dc microgrids powered by other types of source converters. At this...Show More
A Thevenin network impedance at the point of connection and the impedance of a power electronic converter can be used to evaluate the stability of a power converter under test. With a surge in the power electronic converters in the power systems, the Thevenin network impedance itself is influenced by the power converter dynamics. This paper explains the small-signal stability impact of parallel-co...Show More
Filters are key equipment in LCC-HVDC projects. It filters out characteristic harmonics generated by the converter and prevents the effect of harmonics generated by converters on the AC power grid. Currently, most DC transmission projects use passive filters. The first use of hybrid active power filters in the Fujian Guangdong DC interconnection projectºThis paper introduces the application framew...Show More
We address the design of the Power Takeoff (PTO) device of a wave energy conversion system through direct optimisation of the parameters of a mechanical network according to an optimisation criterion linked to power absorption performance. The results are illustrated through simulations and the behaviours of different PTO realisations are compared.Show More