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.
Energy storage systems based on Lithium-ion batteries have been proposed as an environmental friendly alternative to traditional conventional generating units for providing grid frequency regulation. One major challenge regarding the use of Lithium-ion batteries in such applications is their cost competitiveness in comparison to other storage technologies or with the traditional frequency regulation...
This paper proposes a new method to suppress frequency variations of power system with large amount of wind power installed by using the kinetic energy of the wind power generators. In recent years, environmental problems have been becoming serious and wind power generation with less environmental impacts has attracted much attention and introduced. Since wind power generation is an unstable power...
In this paper, an improvement in power sharing for Autonomous Microgrid is well established. All previous studies were based on voltage and frequency droop control to share power between distributed generators. This paper develops a new robust voltage and angle droop control to share power, where its advantage over the common frequency droop is in less frequency variation. The synchronization of Power...
Because of their characteristics, which have been continuously improved during the last years, Lithium ion batteries were proposed as an alternative viable solution to present fast-reacting conventional generating units to deliver the primary frequency regulation service. However, even though there are worldwide demonstration projects where energy storage systems based on Lithium-ion batteries are...
A DC/DC Modular-Multilevel Converter (MMC) is proposed in this paper, in which two modular multilevel converters are linked by a LCL tank. With the proposed converter, the high power medium frequency transformer can be eliminated to simplify the structure, quasi zero-current-switching operation of both MMCs can be achieved to alleviate the switching loss, the voltage stress of internal LCL tank can...
An improved buck-boost + LLC (IBB LLC) cascaded converter appropriate for wide input voltage situation is presented in this paper, which can be used as a constant voltage source or a constant current source charger for battery. The control strategy of dual frequency PWM (DFPWM) is introduced. For the LLC converter, ZVS for MOSFETs and ZCS for diode are achieved. As a result, the switching loss is...
The following two types of resonant controllers are mainly employed in stationary reference frame to obtain high performance in voltage-source converters: 1) proportional + resonant (PR) and 2) complex vector proportional + integral (cVPI). The performance analysis and parameter design of these two controllers has been researched in many papers. In this paper, these two groups of resonant controllers...
The light load efficiency has drawn more and more attention for the LLC resonant converters. And the high frequency LLC converters are emerging in recent years. The conventional burst mode control cannot fix to the efficiency-optimal state during the burst-on time. Optimal Trajectory Control (OTC) for burst mode can solve this problem by using fixed 3-pulse pattern; however, the burst operation range...
The internal model principle based Repetitive Control (RC) offers an accurate control strategy for grid-tied power converters to feed sinusoidal current into the grid. However, in the presence of grid frequency variations, the conventional RC fails to produce high quality feeding current. This paper thus explores a frequency adaptive repetitive control strategy for grid converters, which employs fractional...
This paper provides a bridged-T voltage control scheme for a H bridge SiC inverter switching at 150 kHz for generating various waveforms at wide range of frequencies (60 Hz to 10 kHz) which is developed as a core loss test unit. Bridged-T controller attains the advantages of both the open and closed loop controllers. It has the fast dynamic response feature of the open-loop controller and zero steady...
In general, the power systems with high penetration of renewable energies result in a system with a relatively low moment of inertia, and can be susceptible to significant frequency variations. However, the virtual inertia of wind power which imitates the kinetic inertia of synchronous generator can be used to improve the system dynamic behavior. This paper presents a novel hybrid adaptive fuzzy control...
The increase of renewable energy sources and distributed generation may have a negative impact on power systems, specially on weak ones. Therefore, their control systems are acquiring growing importance, with new proposals that aim to contribute to the control and stability of the power system as conventional generating units. This paper studies the effect that a PV system using a synchronous power...
This paper investigates the stability regions of current control for LCL-filtered grid-connected converters, where no active or passive damping is required to stabilize the closed-loop control system. It is already identified in the literature that if the LCL resonance frequency is placed within 1/6 to 1/2 of the system sampling frequency, the grid current control can be directly used without damping...
The Microgrid voltage may deviate from the grid voltage when it operates in islanded mode, which will result in unexpected large inrush currents during the re-connection process. This paper proposed a new self-synchronization control strategy for synchronverter with local loads which utilizes the reference phase angle of synchronverter as the reference angle in the rotating frame. A compensation quantity...
In this paper, a hierarchical control system based on a novel autonomous current sharing controller for grid-connected microgrids (MGs) is presented. A three-level hierarchical control system is implemented to guarantee the power sharing performance among voltage controlled parallel inverters, while providing the required active and reactive power to the utility grid. A communication link is used...
Droop control is an effective power sharing control scheme of distributed generation (DG) inverters in islanding AC microgrid, which can stabilize the grid as long as the distributed generation systems have sufficient residual power. On the contrary, many loads have equipped with power conversion circuits in front to improve the operational efficiency, e.g. air conditioners and LED lighting, which...
Three-phase single-switch boost PFC converter operates in discontinuous current mode (DCM) to achieve PFC. If the duty cycle is constant in a line cycle, the average value of the inductor current in a line cycle is not sinusoidal. The PF is low and the input current contains rich 5th and 7th harmonics. Variable switching frequency control can reduce the input current harmonic distortion. However,...
The capacitive-coupling grid-connected inverter (CGCI) is able to achieve reactive power compensation and active power transfer simultaneously with a low operational voltage. The CGCI is coupled to the point of common coupling (PCC) via a second-order LC circuit, which makes its modeling and current control characteristics differs from the conventional inductive-coupling grid-connected inverter. The...
Conventional single-stage AC-DC LED drivers with a high power factor contain significant LED current ripple at twice the AC line frequency, and require large energy storage capacitors to limit the effect on LED light. Conventional designs and novel control techniques aim to power LED loads with a DC voltage to ensure a limited low frequency current ripple. This paper proposes an average current modulation...
This paper presents a control scheme that is applied on the shunt-type electric springs (ES), which is used to strictly regulate the grid voltage for ensuring local voltage stability and to mitigate the utility frequency deviation. The operating method of the shunt-type ES is discussed. A laboratory-scale 1 kW experiment has been done to verify the proposed control scheme and to validate the feasibility...
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.