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 deals with the AC and DC dynamic voltage control in a hybrid DC/AC Microgrid (MG) with central and distributed Battery Energy Storage Systems (BESSs), applying a power sharing mechanism between the different devices in the MG. The MG is composed by a multiport transformation center and two fixed frequency 3 phase AC Nanogrids (NGs) coupled to a DC bus through 3-phase Power Electronic Converters...
Renewable energy generators, e.g. wind turbines and photovoltaic (PV) arrays, have been increasingly employed to replace conventional gas/steam turbines so as to reduce greenhouse gas emission. However, such generators are normally coupled to the power grid through fast-response power converters without any inertia, leading to decreased power system inertia. As a consequence, system frequency deviations...
Penetration levels of solar photovoltaic (PV) generation on the electric grid have increased in recent years. In the past, most PV installations have not included grid-support functionalities. But today, standards such as the upcoming revisions to IEEE 1547 recommend grid support and anti-islanding functions-including volt-var, frequency-watt, volt-watt, frequency/voltage ride-through, and other inverter...
Frequency and voltage regulation are required to support the grid under different scenarios. In order to handle these scenarios, classical control strategies demand complex systems to fulfill these requirements. However, synchronous controllers are trending strategies to contribute with frequency and voltage regulation functionalities without the requirement of external elements. Among these strategies,...
Nowadays, the Modular Multilevel Converter (MMC) based HVDC has been considered as a promising technology to meet the increasing electric power demand. However, constructing new transmission lines becomes more and more difficult because of environmental issues. Consequently, the newly constructed DC lines have to share the right of way with existing AC transmission in close proximity. Meanwhile, as...
The appearance of harmonics in the grid voltage is an issue for the generation systems and grid connected consumers. This paper presents the basic control strategy to be implemented in Synchronous Power Control (SPC) based power converters, which contributes to reduce the harmonic content in the voltage by means of injecting different harmonic current to the grid using a separated virtual admittance...
This paper proposes a fixed frequency based sliding mode (SM) controller for transformer-less single phase inverter for photovoltaic (PV) application with active power decoupling minimizing the capacitance requirement. Unlike conventional power decoupling techniques in full bridge converters, the proposed technique incorporates a large sinusoidal swing of the half-bridge capacitor voltages and a limited...
Because of the differences in line impedances, parallel inverters with conventional droop control will have huge circulating current, which does not flow through the loads. To mitigate the circulating current, the research in this paper finds out that parallel-operated inverters should have the impedance in inverse proportion to their capacities, which is difficult to realize in practice. To meet...
This paper proposes a control structure of SST (Solid-state-transformer), which consists of MMC (Modular Multi-level Converter) based AC/DC converters and isolated DC/DC converters, to reduce the size of capacitors. The phase separated configuration requires a high capacitance needed for smoothing capacitors due to instantaneous power oscillation at the double line frequency. This paper proposes an...
In order to address the economical dispatch problem in cascaded microgrids, this digest proposes an optimal economical-sharing scheme via decentralized approach only with the local information. This overcomes the limitations of centralized control, where the central controller and external information exchange are needed. The frequency and current are used as carriers driven the distributed generators...
A control scheme using space vector modulation for the modular multilevel matrix converter (MMMxC) without circulating current control is investigated. The circulating current flows spontaneously among all the nine arms to balance capacitor voltage of cells. A small arm inductor is inserted into each arm to suppress the di/dt and peak value of transient arm current at the moment of switching the cells...
In this paper, first, the existing frequency and voltage amplitude restoration control strategies are reviewed. Moreover, the proposed second order washout filter control strategy is proposed to enhance the dynamic response under load disturbance. The physical parameter of the proposed method is derived, and system stability for the system parameter is discussed. Finally, extensive simulation results...
Fault current limiters (FCLs) are one class of solutions to cope with the upcoming challenges in microgrid protection. Considering high penetration of distributed generations (DGs) in microgrids, the necessity of designing cheap and effective FCL is getting higher. This paper attempts to fill this gap by proposing an embedded FCL operating based on modifying the secondary control of DGs. As this method...
This paper proposes a novel universal control for multi-bus AC microgrid with the capability to operate in both grid-connected (GC) and islanded (IS) modes. The control scheme is based on distributed manner, and the leader-follower consensus protocol is designed. Only few leader distributed generators (DGs) receive the correction signals from the unified mode controller, which is installed at the...
In this paper a current-limiting droop control of grid-tied inverters that introduces virtual inertia and operates without a phase locked loop unit is proposed. The proposed controller inherits a self-synchronization function and can guarantee tight bounds for the inverter frequency. In addition, using nonlinear Lyapunov theory, it is analytically proven that the inverter current never violates a...
In order to offer a good power quality for end users in islanded microgrids, the power sharing between distributed generators (DGs) is the first challenge that must be ensured. In this paper, a droop control method based primary control for two parallel single-phase VSIs forming an islanded microgrid is presented. The proposed control consists of two DGs local controllers, where each controller includes...
We propose a plug-and-play realization of the virtual infinite capacitor (VIC), which is an electronic circuit recently proposed in the literature for DC voltage filtering. The VIC is meant to replace large, expensive and unreliable electrolytic capacitors, and is mainly intended for applications where random fluctuations of the DC bus voltage may occur (i.e., the VIC is not tuned to one particular...
A robust grid structure, which makes use of distributed renewable energy generation, should consist of grid sections, which are able to seamlessly switch between grid-connected and islanding mode of operation. This way, failures in the upper level part of the grid can be mitigated. This contribution discusses local and supervisory control strategies, and requirements for microgrids. A robust hierarchical...
This study presents a robust estimation control technique of single stage grid connected solar PV (Photovoltaic) energy conversion system with distribution static synchronous compensator (DSTATCOM) capabilities. The estimated perturb and observe (EPO) based maximum power point tracking (MPPT) algorithm is used to obtain crest power from solar PV array under varying atmospheric conditions. The proposed...
The paper presents an overview about operation and control of the inverter-interface generation units (IGUs) when connected to a microgrid either alone or together with other generation units. The following key connection paradigms are considered: i) one IGU and a grid, ii) one IGU and one machine-interface generation unit, iii) a single IGU, and iv) two IGUs. After illustrating how the IGUs operate...
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.