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With an expansion of using renewable energies, the bus voltage fluctuation should be considered in designing the control circuit of power converters. This paper presents a new fast maximum power point tracking (MPPT) control for solar panels under the bus voltage fluctuation. The proposed method uses a derivative control to the reactor current of the dc-dc converter to improve the transient response...
This paper introduces a simple and effective control algorithm for generation of reference voltages based on Three-phase dual SO-SOGI (Second Order-Second Order Generalized Integrator) based Phase Locked Loop (PLL) for DVR (Dynamic Voltage Restorer). The proposed DVR scheme is implemented to achieve faster compensation of voltage sag, swell with and without phase jump and at harmonic conditions. Three-phase...
The four-level Hybrid Clamped Converter (4L-HCC) is emerging as a promising DC/AC converter topology for high-efficiency medium-voltage drives. However, without proper control, the voltage fluctuation of the DC-link capacitors will be excessive, resulting in distorted AC current and stability issue in low frequency operation. In reality, the distorted current makes it impractical for motor drive during...
Excessive voltage fluctuation has been a problem existing and to be solved at grid connected point of wind farm, on which, the paper develops the study by taking the double-fed wind farm as an example. First, it studies and deduces the DFIG model and the equation for voltage of grid connected points of double-fed wind farm and analyzes the vector control strategy of DFIG gird-connected system in theory...
The paper presents a comprehensive Power Quality (PQ) solution to improve grid current harmonics and light intensity flickers in large scale LED lighting networks. Low cost and low power LED lamps exhibit current harmonic contents due to their nonlinear characteristics. A large scale lighting network requires tens to hundreds LED lamps installation, the resultant harmonic currents pollute the grid...
This paper realizes a high power factor, high reliability, and low cost PMSM drive system with small DC-link capacitor. Compared with conventional bulky electrolytic capacitor for the regulation of DC-link voltage, a small-size film capacitor with capacitance reduction to 1% is used to realize a seneorless PMSM drive with high power factor, high reliability, and high compactness. To overcome high...
PV system integration with power grid has many challenges. One of these challenges, the disconnection of PV inverters from the grid under grid faults; these disconnections lead to a stability problem in larger scale of PV power plant. This paper is focused on the comparison of some Low voltage ride-through strategies. The two-stage PV inverter configuration and its conventional control methods were...
In railway traction applications, due to the limitation of switching frequency and the attempt to fully utilize the DC-link voltage, the traction inverters usually work in six-step (or quasi-square-wave) mode under heavy load or high frequency condition. Meanwhile, DC-link voltage fluctuation, stemming from a common single-phase grid-side power supply, has a great impact on the drive system. To maintain...
This paper describes transient response improvement of digitally controlled synchronous rectification buck-type dc-dc converter using feedforward compensation. Transfer function of the feedforward element was introduced by the state space equation. The steady state characteristics of the converter using the feedforward element were same as the converter without using the element, but transient responses...
Although the wireless power transfer (WPT) has been used in a wide range of areas, there are many difficulties with the development of WPT. The load voltage quality problem caused by the high susceptibility of the delivered power to the surrounding is still a key issue to be solved. To guarantee a high quality of dc load voltage in WPT system, this paper proposes a novel voltage control strategy based...
This paper presents the concept of a compensator of voltage sage/swell installed in connection terminals of small industrial plant or selected loads. This compensator based on a three-phase hybrid transformer with matrix converter. Presented in this paper is an approach for obtaining continuous control of the voltage magnitude and phase shift using a conventional transformer with two windings and...
Due to the increased renewable power penetration level renewable power plants have to provide low-voltage ride-through (LVRT) capability with simultaneous dynamic voltage support, to ensure the grid stability during grid faults. Concerning doubly fed induction generator (DFIG) based wind energy conversion systems (WECS) large electromotive forces and rotor currents, which may damage the rotor-side...
The papers presents implementation of a 600 kW DC power converter resistant to electrical network perturbations on an 18 kV electrical network feeding the input of the power converter. The manuscript describes experimental assessment of converter output performance during both nominal electrical network conditions and transient grid voltage dips.
The main objective of this paper is to present a suitable dynamic model for a high-voltage dc link based on voltage source converters (VSC-HVDC), with fault ride-through (FRT) capability, suitable for dynamic studies dealing with island interconnection projects where external ac links are also present. The analysis provides insight to the expected response of dc and ac interconnectors operating in...
In this paper, a simple limited current injection method is proposed for the operation of DVR under grid voltage deep sags. The proposed method considers the impact of couplings between load power factor and grid voltage sag depth to calculate the minimum injection current that can preserve satisfaction grid voltage compensation under deep sags, Accordingly, the over current tripping off problems...
Voltage dip has become the most user complaint problems about power quality, in order to ease voltage dip to guide the operation, planning and transformation of power grid. In this paper, based on the voltage dip caused by four kinds of busbar fault, the voltage dip matrix of each type fault is established, the grid structure evaluation indexes based on voltage dip is proposed. Based on the column...
Voltage sag is a common dynamic power quality problem. They can cause great economic losses in industrial facilities. The present paper describes the behavior of an electrical power distribution system with doubly fed induction generator (DFIG) based wind farm. The developed system is simulated in Matlab software Simulink. Sags are often caused by short-circuit faults in the power network and are...
Unpredictable power quality (PQ) events such as, balanced and unbalanced voltage sag/swell, frequency shift, phase jump and harmonic distortions in the utility grid voltage drastically affects the performance of a grid interfaced distributed generation (DG) systems due to unreliable synchronization. This paper presents adaptive synchronization based dq-current control technique for three-level NPC...
In low-voltage ride-through or unbalance gird voltage condition, the fundamental fluctuation in the neutral-point (NP) voltage of three-level voltage source converter will appear under imbalanced grid voltage situation and has not been researched in detail. A new NP current model under imbalanced grid is developed to investigate the limitations of conventional nearest-vector modulation and to give...
Modular multilevel converter (MMC) receives wide acceptance in high power, high voltage applications. However, large capacity capacitors are needed in the sub-modules due to low frequency fluctuation power. The voltage fluctuation is even larger especially in the startup of Motor drive or low frequency output application. Besides, the integrated energy storage systems (ESS) in MMC is used for recovering...
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