The Thyristor Switched Parallel Capacitors (TSPC) Converter for Power Factor Correction in Wind Power Systems

This paper presents a novel power factor correction circuit suitable for low-speed electric generators usually used in direct drive wind turbines. The Thyristor Switched Parallel Capacitors (TSPC) circuit belongs to the Controlled Series Capacitor (CSC) circuits. Those circuits have been used in power transmission lines to correct the power factor and improve the performance of the electrical system. Such a circuit can be used in wind power systems to improve and maximize the efficiency of a wind turbine. A typical direct-drive wind power system employs variable speed electric generators, but the downside is that systems like that suffer from high and variable inductive reactance. In order to correct the power factor and to improve the efficiency of the system, the inductive reactance of the generator must become equal in value to the capacitive reactance. A TSPC circuit uses a set of capacitors, connected in series with anti-parallel thyristors. In every cycle, a controller triggers the appropriate thyristors, allowing the current to pass from the capacitor which then provides the system with the capacitive reactance that matches the generator’s inductor reactance. Therefore, the TSPC circuit is able to counteract for any reactive losses and improve the power factor, as well as, the efficiency. This paper introduces this novel power factor correction circuit that employs capacitors in parallel configuration. This circuit was simulated in PSPICE and was implemented and tested in the lab. Based on the simulation and implementation results, we discuss the benefits as well as the drawbacks of the proposed circuit

VAR Compensation on Load Side using Thyristor Switched Capacitor and Thyristor Controlled Reactor

Generally, AC loads are the inductive loads which are reactive in nature. These loads, thus, demand and draw reactive power from the supply source. If these loads draw large lagging current from the source, this will cause excessive voltage drop in the line, which can even cause the voltage collapsing in the line itself if the drop in the line is excessively high. VAR compensation means efficient management of reactive power locally to improve the performance of AC power systems. In this paper, Static VAR Compensator, using TSC (Thyristor Switched Capacitor) and TCR (Thyristor Controlled Reactor), is designed and simulated in MATLAB to maintain the power factor of power system nearly to unity at all times. TSC and TCR are basically shunt connected capacitors and inductor respectively whose switching (of capacitors) and firing angle control (of inductor) operations are carried out using thyristors. The purpose of capacitors is to supply lagging VAR as per the demand by the connected loads and the overcompensation due to excess VAR generated by the discrete set of turned on capacitors are absorbed by the adjustable inductive reactance of the inductor in TCR branch through firing angle control mechanism.

The Effect of Capacitance on the Power Factor Value of Parallel RLC Circuits

The power factor of the circuit is determined by the amount of pure resistance (R), self-inductance of the coil (L) and the capacitance of the capacitor (C). In this study, the measurement of the power factor value in a parallel RLC circuit was carried out through experimental testing and simulation with the value of C as the independent variable, while the values of R and L were fixed conditioned quantities. The purpose of this study was to determine the effect of capacitance on a parallel RLC circuit. One of the ways to improve the power factor value in a circuit is to install capacitive compensation using a capacitor. The relation between the power factor value and the capacitance and inductive reactance based on the experimental results and the simulation calculation results in the parallel RLC circuit both shows the same pattern with a relative uncertainty below 8%. The experimental results and simulation results both show that the power factor can be improved by using a right capacitance which is around the capacitance value when there is resonance in the circuit.

Plant Electrophysiological Information Manifests the Composition and Nutrient Transport Characteristics of Membrane Protein

Background: Almost all life activities of plants are accompanied by electrophysiological information. Plant electrical parameters are considered to be the fastest response to environment.Results: In this study, the theoretically intrinsic relationships between the clamping force and leaf resistance (R), capacitive reactance (Xc) and inductive reactance (XL) were revealed as 3-parameter exponential decay based on bioenergetics for the first time. The intrinsic resistance (IR), intrinsic capacitive reactance (IXc) and intrinsic inductive reactance (IXL) in plant leaves were monitored via these relationships for the first time, and the nutrient transport capacity (NTC) in plant cells based on IR, IXc and IXL was first defined. The results indicate that IXc and IXL could be used to manifest the composition of surface and binding proteins in cell membrane, plant with high crude proteins and crude ash had higher NTC, and which accurately revealed the nutrient transport strategies in tested plants. Conclusions: This study highlights that plant electrophysiological information could effectively manifest the composition and nutrient transport characteristics of membrane protein in plant cells.

МОДЕЛИРОВАНИЕ ИЗМЕНЕНИЙ В ГЕОМЕТРИИ КРЫЛА ПРИ ИХ СОГЛАСОВАНИИ С ПАРАМЕТРАМИ СИЛОВОЙ УСТАНОВКИ

Development modifications of aircraft have become the main direction of development of transport category airplanes, including military transport (МTА). However, there are several ways to solve such tasks:– to leave the same area and other geometric parameters of the wing and the problem are solved by significant changes in the power plant;– change the wing area and the aerodynamic configuration with the same parameters of the power plant.Both these ways have their advantages, but their implementation raises a number of problematic issues:- excessive growth of the starting mass modification;- the deterioration of its takeoff and landing characteristics;- deterioration in fuel efficiency and other technical and economic indicators, which leads to a decrease in the competitiveness of the modification.The most effective is getting the new aircraft when an agreement is called, changes are already in the preliminary design phase of the modification.The article formed the scheme of approval of such changes, with the essential growth of the load capacity, range, and improved fuel efficiency of the designed modifications. A distinctive feature of the proposed scheme is that modification changes the geometry of the wing reduces the magnitude of its inductive reactance at a predetermined lifting force.A model of the influence of design changes in the geometry of the wing, such as the narrowing and the corners of the geometric twist of the local chord along the span, expressed via the coefficients of the ellipticity of the trapezoidal wing, to change the polars of the wing and its aerodynamic quality.Developed a step-by-step evaluation of the aerodynamic performance of the required values of the coefficients and , the magnitude of which is stipulated by the conditions of approval modifications to the wing and thrust characteristics of the power plant. This is an area , in which a possible implementation of the required increase in capacity modifications.The obtained results related to the modeling of changes in the geometry of the wing are an integral part of the scheme approval deep modifications in the wing and the power plant is required when creating modifications with enhanced performance.

Study the Effect of Serial Inductance on Reducing the Current Harmonic Distortion of Three-Phase Bridge Rectifier

The aim of this paper is to analyze the influence of adding serial inductance in AC side of the ‎‎3ph -6 pulse bridge rectifier on the reduction of harmonic distortion rate. A simulated model ‎with serial inductance was analyzed. The 3-phase 6-pulse diode bridge rectifier was chosen ‎because it corresponds to the operation of the 6-pulse thyristor bridge rectifier at maximum ‎load (while keeping the angle α = 0). Both the total harmonic distortion (THDi) and the ‎power factor (PF) for the circuit have been measured. The results obtained of the THDi has ‎been recorded for four values of serial inductance and results was compared with the (IEEE 519-1992) standard. Comparison results indicates ‎that for values of inductive reactance (Xi) up to 67% cause a reduction of THDi which is above the standard values, while for (Xi) more than 67% cause a reduction in THDi within the acceptable standard level. Analyzing of results prove that the adding of serial inductance at the AC ‎side leads to good reduction in harmonic distortion rate, but with some reduction in power ‎factor value, which results in some energy losses.

Theoretical study of ground radiation tag antenna with Tunable open-slot exciter

A novel radio frequency identification tag antenna is composed of a resonant open-slot exciter and a dipole-type ground radiator. For a conjugate match to the Alien Higgs-4 chip impedance of 8−j149 Ω at 925 MHz, a quarter wavelength open-slot resonator embedded at the center of the dipole-type ground plane (130 × 18 mm2) was investigated and fabricated. Simple size adjustments and various loaded inductor of the open-slot resonator allow for easy control of the tag antenna resistance and inductive reactance, from which the chip impedance requirement can be easily obtained. The read range of the prototype antenna attached on a foam in the free space can reach more than 9 m, which has been tested for a radio frequency identification reader with 4.0-W of effective isotropic radiated power. Measurement data are in good agreement with simulation results.