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Voltage unbalance or sag conditions generated by the power system faults can have a significant negative impact on the ASD's (Adjustable Speed Drives). A practical ride- through scheme based on supercapacitor/ battery as an energy storage device for ASD's is presented in this paper. Energy storage module is connected to support the DC-link voltage during power system faults. The performance of ASD's...
The Coupled Inductor Bidirectional DC-DC CI-BDC converter can help for the effective use of ESS due to its low voltage device stress, high voltage diversity and efficiency in nature. Thus, enables battery module of low voltage to be interfaced with the high-voltage dc bus or the micro grid for subsequent use. However, the converters' inductor leakage energy problem limits their applications. The authors...
In this paper, a new reference waveform estimation strategy based on an adaptive notch filter (ANF) is proposed for unified power quality conditioner (UPQC). Two coupled ANFs are used to generate the reference waveforms for shunt and series components of UPQC. Mathematical properties of proposed algorithm are presented in detail. The technique is simple and its speed and accuracy are controllable...
This paper discusses the performance benefits and energy efficiency improvements from microprocessors that communicate with their power supply. The power supply's response to computing load changes can be vastly improved with information about expected transients. Supply voltages can be modified to decrease steady-state power losses. A microprocessor can also adjust its computational activity based...
In power system, the voltage pulsation and deficiency or surplus of reactive power will have a great effect on the quality of electric power supply. Through the appropriate and effective way of compensation, we can keep the balance of reactive power in the maximum degree by the maintenance of acceptable voltage. That's to say, quality of power supply can be improved greatly by the synthetic compensation...
In this paper, an experimental analysis of the serial merged flyback-forward converter is carried out and its use as a single-stage single-phase power factor corrector for isolated power supplies is showed. Two correctors were built using commercial integrated controllers and their performances were tested based on the power factor and dynamic response of the output voltage.
This paper aims to model, using the software ATP (Alternative Transient Program), and investigate the use of zigzag autotransformer (ADZ), with control of voltage module and phase shift made independently, as a filter for harmonic currents, specifically in 24-pulse converters. Objective is to preserve the quality of supply in terms of the harmonic distortion. Furthermore, the systematic focus here...
In this paper novel voltage mitigation method is introduced to protect sensitive loads due to under voltage or by over current. It will be able to compensate voltage sags on critical loads dynamically. It consists of voltage source inverter, injection transformer, filter and energy storage device. The efficiency of the mitigation method depends on the efficiency of the control techniques involved...
The Inter-Line Dynamic Voltage Restorer (IDVR) consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder (voltage control mode), the other inverters pump the required power into the dc bus (power control mode). Each inverter will have both voltage and power...
In this paper, a dual-loop control scheme is proposed for inverters in three-phase four-wire microgrid applications to improve the power quality within the microgrid and the power quality of the current flowing between the microgrid and the utility grid. The control scheme involves an inner voltage loop and an outer current loop, with both controllers designed using the H∞ repetitive strategy. This...
In this paper, a new type of Lyapunov function based load voltage tracking controller is proposed for series connected PV inverter for grid voltage disturbances compensation. The inverter operates during the day time as an active power compensator as well as load voltage regulator under grid voltage sag, swell or even under normal condition. The compensating voltage provided by the inverter is added...
The ballast system and the lamp are subjected to the utility disturbances. In this way, HID lamps are very sensitive to voltage supply fluctuations that produce an effect on the human visual perception by changing the light emission, known as flicker. New design considerations and a control strategy for a two-stage ballast system, power factor correction (PFC) and inverter stage, for high intensity...
This paper analyses the behaviour of a full-converter wind generation system with a back-to-back conversion structure using Neutral Point Clamped (NPC) converters during network faults. A Permanent Magnet Synchronous Generator (PMSG) is used as the generator. The main problems of this structure during voltage sags are firstly, the accumulation of power in the DC-link due to the reduction of power...
One of the main issues related to the integration of Distributed Generation (DG) in the utility grid is safety. The protection schemes of distribution systems are usually designed under the assumption that power flows from distribution system to end users. If a fault takes place and a breaker opens, all circuits downstream will be deenergized. However, this is not the case when a DG is used, and it...
Distributed power generation systems (DPGS) are based on the grid-converters as interface between the source and the grid. They require a control strategy is designed in order to guarantee system stability and reliability. The effect of converter outages should be properly studied as well as the effect of power quality disturbances. The aim of this paper is to provide a comprehensive analysis of these...
This paper presents an improved technique for the power quality of the electrical part of a wind generation system with a synchronous generator (SG). The main aim is to optimize the utilization of wind power injected into the grid. To realize this goal, an uncontrolled rectifier-digitally controlled inverter (URDCI) system is proposed. The advantage of the proposed system is its simplicity due to...
The rate at which large variable speed wind farms are being developed had increased rapidly as the demand for green energy has grown. With this increase in distributed energy penetration into power networks, the main focus must be on power quality (Voltage Quality and Supply Reliability). However, new grid codes require wind energy generating systems to ride through grid faults, and at the same time...
The ride-through capability issues associated with adjustable-speed drives (ASD) have become an important area of concern due to the susceptibility of ASD to power interruptions. Furthermore due to the absence of the dc link capacitor in matrix-converters (MC), MC adjustable speed drives are more vulnerable to such power disturbances. This paper presents a study of a ride-through strategy for MC adjustable-speed...
Effect of a new parameter of voltage sag, i.e., phase angle jump, on invertors for PV System was surveyed by newly developed Voltage Sag Generator. The generator can reproduce actual voltage sags recorded past, and artificial voltage sag with controlled phase angle jump. It consists of PC, D/A converter and power amplifier. A program generating wave form of sag has been developed and improved considering...
This paper presents the development and implementation of a three-phase universal active filter consisting of three single-phase modules. Each single-phase module is controlled by a digital signal processor. The proposed active filter can compensate the present harmonic distortion in the voltage, as well as under and overvoltage. It also compensates the current drained by the load connected to it,...
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