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Due to the complex and nonlinear nature of electric railway supply system the system is a good candidate for the resonance occurrence. Resonance can boost some voltage or current harmonic components and may cause damage to the network equipment. Therefore resonance assessment and finding the resonance frequencies in the electrified railway system is important. In order to evaluate frequency response...
The increase in non-linear loads in the electrical network deteriorates the voltage waveform quality. One of the most used methods to correct the quality lack is to use shunt, series or mixed topologies of active power filters. Mixed filters can compensate loads that generate voltage harmonics and current harmonics, but the economic investment is high. Commercial shunt filters are more widespread...
A phenomenon that occurs when using the DQ Transformation to obtain the compensation references in active filter applications is presented in this paper, in which new harmonics that had not existed originally in the system, are injected to it. Although these new injected harmonics have very low magnitude, they do exist and correct processing must be assured in order not to increase their magnitudes...
This paper presents a literature review about unbalance in power systems and a case study about unbalance measurements in the Main Interconnected Network (MIS) of Oman. A review of unbalance causes, negative impacts, mitigation techniques, quantification indices and limits are presented. Moreover, voltage and current unbalance measurements at three grid stations that supply the three main industrial...
In this paper a novel hybrid harmonic compensation approach for non-linear loads is developed and analysed. This technique provides compensation for current harmonics coming from a nonlinear load and reactive power regulation even during grid's voltage disturbances. The method could be implemented on any Series Active Filter. Meanwhile the Transformerless configuration (TSeAF) is selected in this...
This article aims to develop a model of forward-looking management of battery technologies. For the construction of this model the methodology of Future-Oriented Technology Analysis has been adapted. The article first examines the available energy storage technologies, then selects and synthetically characterizes the future, emerging technologies requiring carrying out the development path with a...
This paper compares classification techniques to identify several power quality disturbances in a frame of smart metering design for smart grids with high penetration of PV systems. These techniques are: Linear Discriminant Analysis (LDA), Nearest Neighbor Method (kNN), Learning Vector Quantization (LVQ) and Support Vector Machine (SVM). For this purpose, fourteen power-quality features based in higher-order...
This paper proposes the new implementation of Finite Control States Set Model Predictive Control (FS-MPC) applied to 3-level 4-leg Flying Capacitor Converter (FCC) operating as a Shunt Active Power Filter (SAPF). The developed approach is based on three important issues that are described. The first is addressed to the phase to phase model of the 4-wire system to simplify the prediction equations...
This paper presents the proposal of a three-phase current-source shunt active power filter (CS-SAPF) with photovoltaic grid interface. The proposed system combines the compensation of reactive power and harmonics with the injection of energy from a solar photovoltaic array into the electrical power grid. The proposed equipment presents the advantage of giving good use to the current-source inverter,...
With the increased number of wind turbines being directly connected to the power grid comes new challenges regarding grid integration. Fault ride through capability during voltage sags are among the most challenging issues. Conventional ride through techniques result in a compromised control of the turbine shaft and grid current during deep voltage sags. In this paper, an integral terminal sliding...
Current source cascaded H-bridge (CSCHB) inverters can be a good alternative to manage voltage, current and frequency in a medium-voltage load. The power quality achieved by this type of converters and their ability to boost the output voltage without the need of a DC / DC converter in the DC link, have drawn attention to it as a suitable alternative to be used as the interface between DC sources...
Due to constantly increasing share of renewable energy sources in total installed power, transmission system operators must adhere to ever stricter grid codes in order to maintain stable, secure and reliable power system operation. Grid codes in most of the countries with significant share of wind power require from wind power plants to participate in active and reactive power control, to stay connected...
Reactive power handling by distributed power generation systems (DPGS) was prevented in the past in order to avoid additional power losses in the distribution feeders, however several new national grid codes request reactive power generation/absorption by the converters of active users. Actually almost no literature is focused on power losses analysis in case of reactive current circulation from the...
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