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Installing the battery energy storage in the interlinking converter of hybrid AD-DC grid can effectively reduce the exchanged energy of hybrid grid and therefore reduce the losses. Being different from the two-level or three-level interlinking converter for low voltage grid application, this paper proposes an interlinking modular multilevel converter (MMC) with integrated battery energy storage for...
Photovoltaic power plants (PV) are equipped with anti-islanding algorithms, embedded in the converters controller, to avoid the island operation. However, the current trends in the development of the future electrical networks evidence that it is technically feasible and economically advantageous to keep feeding islanded systems under these situations, without cutting the power supply to the loads...
This paper proposes a variable sampling frequency model predictive control (VSF-MPC) to achieve fixed-switching frequency operation for a neutral-point clamped (NPC) inverter. The proposed control technique simultaneously considers load current control, balancing of DC-link capacitor voltages, mitigation of common-mode voltage, and elimination of even-order and inter-harmonics in the load current...
This paper presents a predictive current control strategy with active damping method applied to a current source inverter. This control strategy uses a discrete-time model of the system to predict the future value of the grid current for all possible current vectors generated by the inverter. According to a cost function that minimizes the errors of the predicted grid current and the reference grid...
The concept of Double-Delta Sourced Transformer (DDST) had been proposed to eliminate passive filters in large-scale power conversion systems. For the grid connection, active and reactive powers in DDST must be under control. In this paper, the power modulation method is proposed for DDST through the current regulation. And, it is also considered when one of converters is disconnected from the transformer...
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...
Zero-Voltage Transition (ZVT) DC-DC converters with active snubber can be used in photovoltaic applications requiring high efficiency and high-frequency isolation transformer. In order to improve the dynamic response of ZVT converters, two different current control strategies, namely Feed Forward and Dead-Beat, are proposed. The Feed Forward and Dead-Beat control, both based on the converter electrical...
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 combination of deadbeat controller and open-end winding topology is effective for improving the response of current control of induction motor drive system. A deadbeat current controller achieves high gain by compensating the delay element of digital controller with current prediction and excluding it from the control loop. The response of a deadbeat current controller depends on the duration...
High-speed regimes allow to increase the power density of electrical drives, which is a necessary characteristic in aeronautical applications. In such a context, together with the typical non-linearity of low speed drives, such as core saturation, phenomena related to high fundamental to sampling frequency ratios appear increasingly significant. This paper applies methodologies based on modern robust...
Active damping of LCL-filter resonance based on single-state feedback control is widely used with voltage source converters. Its robustness against grid impedance variation has always been a major concern with its controller design. To deal with this issue, this paper begins by developing a generalized impedance-based model of grid current control with feedback-type active damping. Then, a controller...
Predictive current control (PCC) methods have been widely implemented for grid-connected voltage source inverters (VSIs) recently to achieve better output performance, however, facing the challenge of high sensitivity to uncertain system disturbances and inevitable time delay. In this paper, a new PCC scheme has been proposed for a single-phase VSI to improve the quality of the current fed to the...
Single stage Flyback converter with active power factor correction (PFC) function built-in is very popular for low power LED driver application. However, a universal driver design (120V∼277Vac wide input) for meeting PF>0.90 and THD<20% at 50% of maximum output power remains very challenging using peak current transition mode (PCTM) PFC control. Therefore, in this paper, a novel and practical...
The DC transmission system provides a cost effective solution for long distance power transmission compared to the AC transmission system. Hence, this has increased the emphasis on the development of the DC transmission system. Development of power converter with modular structure has now made it possible to achieve higher voltage and power level. This opens the possibility for further development...
Grid connected Electric vehicles (EVs) and Plugin hybrid electric vehicles (PHEVs) can benefit the grid by utilizing Vehicle-to-grid (V2G) technology. V2G enables stored electrical energy in electric vehicle batteries to be returned to the grid for peak demand and other ancillary services. Typically, the onboard electric vehicle battery charger is uni-directional but needs to be bi-directional to...
Modular multilevel converters with storage devices integrated in the submodules are emerging topologies for traction drives. This paper proposes a new state-of-charge control technique to optimally utilise supercapacitor cells that are connected to the sub-module capacitors by means of boost DC/DC converters. The proposed strategy ensures that the charging/discharging trajectory of all the supercapacitor...
Passive damping is proven as a robust stabilizing technique for LCL-filtered voltage source converters. However, conventional design methods of passive dampers are based on the passive components only, while the inherent damping effect of time delay in the digital control system is overlooked. In this paper, a frequency-domain passivity-based design approach is proposed, where the passive dampers...
This paper proposes a testing method for the evaluation of the inverter dead-time voltage error and the related compensation schemes using a hardware-in-the loop converter topology. The inverter under test is operated as a voltage source that is connected with another twin inverter acting as a virtual load. The virtual load is operated as a current-controlled voltage source converter that draws specified...
The development of distributed generation (DG) systems has led to the increasing use of voltage source inverters. However, step-changes in the modulated voltage can produce dangerous peak common-mode currents (CMCs), which can interfere with the power system ground and cause detrimental effects on other equipment. In this paper, the root cause of CMCs is explored and analyzed. After this, a new method...
Parabolic current control is an attractive current control method with fast transient response and constant switching frequency. Due to the good dynamics of parabolic current control, it can be employed in voltage source inverters to improve the system performance such as minimizing the distortion of current waveforms or voltage waveforms. To implement parabolic current control, a current sensor is...
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