The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper proposes a grid code for photovoltaic (PV) integration to mitigate overvoltage and voltage variation problems caused by a large amount of PV generation in distribution circuits. According to the simulation results, PV generation causes overvoltage and voltage variation problems in distribution circuits. To mitigate the overvoltage and voltage variation problems due to the high penetration...
An average power sharing control strategy for parallel operation of voltage source inverter (VSI) based modular Uninterruptible Power Systems (UPSs) is proposed in this paper. The presented method is based on a modified droop control. The proposed method conquers the drawback of conventional droop plus virtual impedance control, and at the same time some challenges in the real applications have been...
Almost all existing relevant literatures are focused on the multi-inverter system that only contains one type of inverter. Till now, the interactions in multi-inverter system consisting of polytype inverters have been not investigated systematically. To fill this gap, the paper is aimed at the stability study of the generic system containing multiple types of inverters. The mathematic model of interactions...
In cascaded-type microgrid, the synchronization and power sharing of distributed generators (DGs) become two new issues that needs to be addressed urgently. In this paper, a unified droop control is proposed and its stability is analyzed in the islanded mode. The proposed scheme can ensure the system stability and accurate power sharing without communication in four-quadrant operations. Finally, simulation...
Impedance source inverters have attracted much attention in recent years due to their ability to behave as voltage elevators/reducers at their output terminals without the need of an extra dc/dc converter to accomplish this task. Among these inverters, the quasi-impedance source inverter (qZSI) is one of the most known topologies. It considers two basic operating states, the no-shoot-through state...
In an islanded microgrid, harmonic current is controlled (or shared) by modifying the effective impedance in the path of harmonic current. This effective impedance includes line impedance and the internal impedance of the generation unit. Reported works consider the aforementioned impedances as separate entities and their combined effect in harmonic current flow has not been discussed so far. This...
With the improvement in the power electronic technologies, medium voltage dc (MVDC) electrical distribution systems are being considered for on-shore and off-shore applications. These future MVDC electrical distribution systems are expected to provide the possibility of easy interfacing of the renewable energy sources, improving the dynamics of the system and also help in reducing the carbon footprint...
Microgrid research and development in the past decades have been one of the most popular topics. Similarly, the photovoltaic generation has been surging among renewable generation in the past few years, thanks to the availability, affordability, technology maturity of the PV panels and the PV inverter in the general market. Unfortunately, quite often, the PV installations are connected to weak grids...
The objective of this research is to analyze and evaluate the performance of the proposed shunt-series switched multi-functional grid-connected inverter (SSS-MFGCI) for mitigating unbalanced voltage sag and swell problem in distributed generation system or microgrid. Three quantitative performance evaluation factors, namely fault level factor, rating factor, and grid stiffness factor, are proposed...
Further growth in renewable energy integration would be dependent on reliability and cost-effectiveness. These two factors can be achieved through power converter topologies that enable transformer-less connection of renewable energy based technology to the grid. This paper presents a three phase five level dual tapped inductor quasi impedance source (qZS)-nested neutral point clamped (NNPC) topology...
Cascaded or distributed module-level inverters are becoming increasingly desirable for photovoltaic applications. The authors have demonstrated an AC-stacked topology that allows each inverter to operate completely autonomously from all the others. The only required communications is a low-bandwidth synchronization signal communicated from the point-of-grid-connection. This paper describes the communications...
This paper presents the design process of a 13.56 MHz 10 kW and high efficiency inverter for wireless power transfer systems. The new 650V E-mode GaN is used in multiphase resonant topology to obtain high output power. The optimized efficiency design and the driver design are presented in detail. The circuit simulation results show that the inverter achieves 10 kW output power with the efficiency...
This paper introduces a closed-loop control architecture for an impedance control network (ICN) resonant dc-dc converter that regulates the converter's output voltage while achieving soft-switching across wide operating ranges. This architecture is based on enhanced phase-shift control of the ICN converter, in which the inverter and rectifier phase-shifts are simultaneously controlled to regulate...
A major drawback of the NPC inverter is an unequal power loss distribution among the power devices which leads to unequal temperature stress among them. Therefore, certain power devices experience higher temperature stress, which is the main cause of power device module failure and thus both the power rating and lifetime of the NPC inverter are limited by the most stressed devices. In this paper,...
A hybrid impedance model of Islanded MicroGrid with Paralleled Inverters Controlled by Droop and PQ Strategies (IMG-PICDPS) is derived, in which the PQ-controlled Inverters (PQ-Invs) are equivalent to Norton's circuits, while the DRoop-controlled Inverters (DR-Inv) to Thevenin's circuits in this paper. An impedance-based stability analysis method is further proposed according to the Nyquist criterion...
Grid-tied Photovoltaic (PV) inverters are required to have harmonics mitigation control to reduce harmonics distortion on the output current caused by the impact of grid background harmonics. In this paper, a decentralized control strategy for reduction of the impact of distorted grid voltage on the AC-stacked PV inverter architecture is proposed. Two control schemes with the selective harmonics mitigation...
Harmonic and interharmonic distortions are considered as the main power quality issues especially in the distribution networks. The double-stage Adjustable Speed Drives (ASDs) in which the front-end diode rectifier is connected to a rear-end inverter through an intermediate DC-link filter may inject significant amount of harmonics and interharmonics into the grid and consequently degrade the grid...
The stability of grid-connected voltage-source inverters (VSI) is deteriorated in a weak grid due to the interaction between the increasing grid impedance and the inherent inverter impedance. To improve the stability of LCL-filtered VSI, an impedance-phase reshaping method is proposed in paper. With this output current feedback compensator, the phase margin at the impedance intersection can be improved...
Electrical resonance with the grid is an increasingly common problem for wind turbines and PV inverters, especially those connected to a weak grid. Such resonance problems can usually be solved by modifying turbine or PV inverter control to reshape its output impedance. There are, however, situations where this may not be effective or not feasible at all due to e.g. limitations in turbine design or...
Full Feed-forward (FF) approach has been proved to be an effective method to suppress the output current distortion of the LCL type grid-connected inverter (GCI) due to grid voltage harmonics. Since most of the existing FF approachs are realized by digital control, a futher study of the digital control based (DCB) FF approach has been carried out in this paper firstly. It is shown that, there are...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.