Voltage regulation in LV distribution networks with PV generation and battery storage

High penetration of photovoltaic (PV) generation in low voltage (LV) distribution networks can leads some power quality problems. One of the most important issues in this regard is the impermissible voltage deviation in periods with a large imbalance between PV generation and local load consumption. Accordingly, many authors deal with this issue. This work investigates voltage regulation for LV distribution networks equipped with the hybrid distribution transformer (HDT), and with high penetration of PV units. A two-stage algorithm for voltage regulation is proposed. In the first stage, a local (distributed) voltage control is performed by minimizing the injection power of the PV-battery storage system (BS)-local load entity at the common bus. In the second stage, optimal coordination is performed between the HDT and the local voltage control. In fact, the second stage is an optimal voltage regulation problem. The aim is to minimize the voltage deviations at load buses by optimal settings the voltage support of the HDT. A PSO algorithm is used to solve this optimization problem. the proposed approach is implemented in MATLAB software and evaluated on the IEEE european LV test feeder.

Sparse coded spatial pyramid matching and multi-kernel integrated SVM for non-linear scene classification

Support vector machine (SVM) techniques and deep learning have been prevalent in object classification for many years. However, deep learning is computation-intensive and can require a long training time. SVM is significantly faster than Convolution Neural Network (CNN). However, the SVM has limited its applications in the mid-size dataset as it requires proper tuning. Recently the parameterization of multiple kernels has shown greater flexibility in the characterization of the dataset. Therefore, this paper proposes a sparse coded multi-scale approach to reduce training complexity and tuning of SVM using a non-linear fusion of kernels for large class natural scene classification. The optimum features are obtained by parameterizing the dictionary, Scale Invariant Feature Transform (SIFT) parameters, and fusion of multiple kernels. Experiments were conducted on a large dataset to examine the multi-kernel space capability to find distinct features for better classification. The proposed approach founds to be promising than the linear multi-kernel SVM approaches achieving 91.12 % maximum accuracy.

Predictive control strategy on an the ultra-high gain DC/DC converter suitable for photovoltaic energy conversion system

This paper presents a control scheme based on the predictive control strategy on an ultra-high gain DC/DC converter with two-phase interleaved structure. the proposed converter consists of coupled inductors and a voltage multiplier cell to increase the voltage gain. due to the variations in the input voltage and the load in the photovoltaic system, tracking the input voltage from its reference value and also dividing the current evenly in the interleaved structure are considered as important control objectives. the proposed predictive control scheme is employed to the proposed converter using two internal and external control loops and the use of a second-order luenberger observer. finally, the effectiveness and the desired performance of the proposed predictive control scheme is verified by presenting the simulation results as the real-time validation by MATLAB and ATMEGA16A-PU.

T-shaped hybrid alternate arm converter with arm energy balancing control for battery energy storage systems

Multilevel voltage source converters (VSCs), such as modular multilevel converter (MMC), cascaded H-Bridge (CHB) and alternate arm converter (AAC), are competent topologies for battery energy storage systems (BESSs) due to modularity, scalability and low harmonic distortion. However, there is a lack of studies about interfacing AAC with a BESS due to the arm energy balancing issue. Redundant sub-modules (SMs) are inserted passively into MMC, CHB and AAC to achieve high reliability; consequently, some of them are constantly idling, resulting in low SM utilization. We propose a novel topology -T-shaped hybrid alternate arm converter (TSHAAC) for BESS applications. In addition to the aforementioned features, the proposed TSHAAC requires lower number of SMs than MMC and AAC, along with lower number of switches than CHB. Moreover, an adapted arm energy balancing control is proposed to take advantage of the redundant SMs that are idling to achieve faster balancing than in conventional AAC configuration. The simulation results validate the integration of TSHAAC configuration in a BESS; the adapted arm energy balancing control is able to improve the balancing duration by 27 %.

Experimental investigation of an unusual induction effect and its interpretation as a necessary consequence of Weber electrodynamics

The magnetic component of the Lorentz force acts exclusively perpendicular to the direction of motion of a test charge, whereas the electric component does not depend on the velocity of the charge. This article provides experimental indication that, in addition to these two forces, there is a third electromagnetic force that (i) is proportional to the velocity of the test charge and (ii) acts parallel to the direction of motion rather than perpendicular. This force cannot be explained by the Maxwell equations and the Lorentz force, since it is mathematically incompatible with this framework. However, this force is compatible with Weber electrodynamics and Ampère’s original force law, as this older form of electrodynamics not only predicts the existence of such a force but also makes it possible to accurately calculate the strength of this force.

Determination of magnetic field intensity on open sample

The work is focused on the refinement of the determination of the magnetic field intensity in a Charpy-shaped steel sample. When measuring on an open sample, the intensity of the magnetic field cannot be determined directly from the current by the magnetizing winding. The distribution of the magnetic field around the sample was determined by numerical simulation, the dependence of its intensity on the distance from the sample surface is fitted with sufficient accuracy by a polynomial of the 3rd degree. A system of sensors sensing the distribution of the field at selected points above the sample was designed; by extrapolation using said fitting function, the intensity of the magnetic field on the surface of the examined sample is determined.

Small size monopole antenna with tri-band notch characteristics for broadband application

In this research article, the design of a broadband monopole antenna with triband notch characteristics is proposed. Notch characteristics are achieved by using an E-shaped slot on the patch and a U-shaped slot on the 50 Ω microstrip feed line. An E-shaped slot is introduced on the metal patch to reject one frequency band of 6.6 − 7.5 GHz and when an additional U-shaped slot is introduced on the microstrip feed line, it provides two-notch frequency bands of 4.8 − 5.7 GHz and 14.2 − 17.5 GHz. The notch bands are effectively used to avoid undesired interference from the WLAN, C band, and Ku band. The proposed antenna provides a very broad frequency range from 3.3 − 19.5 GHz except for three notch bands. The antenna is small in size and easy to design with only a volume of 29 mm × 21mm × 1.6 mm. The antenna is useful for broadband applications.

Fingerprinting/indoor positioning using complex planar splines

The rapid development of various LBS-based applications and services that operate on the basis of the user’s current location, both global GPS and local LBS, today require the development of new and improved methods. This concerns, first of all, methods for determining the local location of LPS users in premises, if there is a high concentration of users and the presence of difficulties in the propagation of radio signals. the use of local methods of location determination based on the fingerprinting method is considered. It is shown that to improve the user positioning accuracy, it is expedient to use a combination of several methods. to determine the local location of the user, a method based on the finite element method and linear complex planar splines is proposed. the construction of linear complex planar splines is considered, their coefficients are found. finding the error in determining the coordinates of the user’s UE location is shown. The use of the proposed method will improve the accuracy of determining the coordinates of the user’s location and will ensure the provision of LBS services and applications to users in the premises under various conditions of their provision.

Influence of saturation levels on transformer equivalent circuit model

This paper presents a modelling approach for a transformer with different saturation levels. First, the magnetic field distributions at different saturation levels in the transformer are analyzed by using numerical simulations. Then, the characteristics of the leakage magnetic flux are analyzed, and the magnetic circuits with varying leakage reluctance topologies are modeled. Finally, based on the mature duality relationship between electric and magnetic circuits, the equivalent electric circuit models are obtained. These kinds of models embody the effect of different saturation levels on the connection points of the leakage flux branches, and it can fully reflect the various working states of the transformer. The accuracy of the models is verified by comparing the circuit simulation results with those of FEM transient simulations.

A wideband dual-circularly polarized traveling wave antenna array

A dual-circularly polarized traveling wave antenna based on linear polarization array with wideband response is proposed. The circular polarization is realized by the sequential rotation arrangement of four linear polarization elements and series feeding with a phase difference 90°. Rotating four of such subarrays sequentially with a phase difference of 90° not only broadens the axial ratio (AR) bandwidth but also corrects the pattern beam deflection. Left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) are respectively achieved by exciting two different ports. The measured impedance bandwidth of the developed antenna array is 27.5 %. The 3-dB AR bandwidths of RHCP and LHCP are respectively 20.7 % and 22.4 % with the peak gains of about 8.7 and 8.3 dBic.