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Airport electrical distribution network has a number of non-linear and single-phase loads that cause imbalances, resulting in significant amount of current flow in the neutral conductor, even under normal operating conditions. The power quality of the airport distribution system is adversely affected by its lighting load controlled by a constant current controller. This paper addresses the related...
The performance of the Grid Connected Inverters (GCIs) (like windmill and large central PV converters) is extremely important related to stable and safety operation of a "Smart Grid" SG. These inverters' control features not only cover the renewable energy conversion and active power feeding into the utility grid but furthermore they cover the helping of the grid voltage stabilization, supporting...
The identification of the sources injecting periodic disturbances in the electric systems is a critical point in the assessment of the electric Power Quality. The available methods, based on a deterministic approach, do not always provide correct results. Methods based on heuristic approaches, such as those based on a Fuzzy Inference System, provide better results, but do not allow measurement uncertainty...
In recent years, voltage and current harmonic problems by the remarkable development of static power converters with nonlinear characteristics have been one of the significant subjects. The authors propose the three phase power quality compensator with five leg circuit by indirect power conversion method. This system can compensate the line voltage harmonics by the series inverter and the load current...
Power quality of electric networks with high penetration of photovoltaic systems has been analyzed in different publications. It has been noted that inverters may increase their harmonic emissions when connected to weak networks, this harmonics may affect other equipments connected to the network and decreasing their performance. This document shows the effects of connecting multiple photovoltaic...
Three-phase currents of STATCOM with conventional control strategy will be unbalanced and distorted when the STATCOM operates at the condition of non-ideal grid voltages. Special attention was paid to the influence of grid voltage quality on STATCOM current and a new control strategy was presented to counteract the influence in this paper. The unbalance and non-sine distortion of grid voltage causes...
This paper presents a new control method to compensate the power quality problems through a three-phase unified power quality conditioner (UPQC) under non-ideal mains voltage and unbalanced load conditions. The performance of proposed control system was analyzed using simulations with Matlab/Simulink program, and experimental results with the hardware prototype. The proposed UPQC system can improve...
In this study, unified power quality conditioner (UPQC) is designed and simulated by synchronous reference frame theory. The proposed system is comprised of series and shunt inverters which can compensate the sag, swell and unbalance voltage, harmonics and also the reactive power. PI controller is used to stabilize DC link voltage and balance the active power between the shunt and series inverters...
The traditional instantaneous reactive theory is one of strategies commonly used in reactive current detection. In reactive current detection of single-phase AC circuits, the traditional instantaneous reactive theory must build a virtual symmetrical three-phase circuit, so its algorithm is complicated and its real-time performance is bad. At the same time, the traditional strategy leads to comparatively...
The characteristic of harmonic currents of high speed train is significantly different from DC-drived locomotives. The rectifier of CRH5 electric multiple units (EMUs) in China is researched in this paper.The principle of four-quadrant converter and its predictive current control strategy are studied. The formula of fundamental and harmonic currents of the parallel two-level four-quadrant converter...
This paper analyses the principle of work of using phase-shifting method to detect power quality (PQ) disturbances based on Hilbert transform (HT). This method is proposed by using phase-shifting for real-time detection on various PQ disturbances, such as voltage swells, voltage sags, voltage fluctuation, harmonics and transient oscillation. Based on the detection platform of LabVIEW environment,...
Harmonics are one of the commonly seen power quality problems. Recently, the adaptive linear combiner (ADALINE) has drawn much attention in many practical applications for harmonics detection and compensation. This paper presents a comparative study of the performances of two weights updating algorithms, improved Widrow-Hoff (WH) delta rule and the Levenberg-Marquardt (LM) method, used in ADLINE for...
This paper presents a structure of modified DC bus interconnected single-phase micro-grid, as well as a topology of power converter building block (PCBB) based on the DC bus to perform various functions in a distributed energy network. The main functions of the PCBB are: compensating the current harmonics produced by nonlinear load in the micro-grid, mitigating the voltage sag or swell of the electrical...
The increased requirements on supervision, control, and performance in modern power systems make power quality monitoring a common practice for utilities. Power quality is the set of parameters defining the properties of power supply delivered to the users in normal operating conditions in terms of continuity of supply and characteristics of voltage (magnitude, frequency, symmetry, waveform etc.)...
A three phase six pulse controlled bridge rectifier with adjustable value of injection third harmonic current is used to control DC drive. In order to improve the power quality of both AC and DC sides of the system the injection circuit parameters have to be varied according to drive loading operating conditions. Therefore the values of injection circuit parameters depend on the firing angle (alpha)...
In this paper, the proposed model of fluorescent lamp with electromagnetic ballast was modified to be able to explain and represent the phenomena of the light flicker mechanism in case of integer and non integer harmonics included in the supply voltage waveform. A new extension on the model was implemented to calculate the harmonic current generated by fluorescent lamp. Total harmonic distortion calculations...
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