Design of a Three-Phase Grid Connector System Using Power Transfer from Park’s Transformation

Instabilities in grid-connected inverters can arise from a number of sources, including mismatched parameters, grid impedance, faults, and feedback delays. Park’s transformation provides accurate control over reactive and active (real) power. This enhances the overall efficiency of the system by enabling operators to control reactive power compensation and optimize energy flow. In dynamic settings, this guarantees greater system stability and faster response times. The current paper aims to improve the grid system by utilizing the dq0 controller. The current work focuses on the analysis based on simulations and theory, where the state space equation serves as the basis for dq-axis current decoupling. A MATLAB platform was used to simulate the complete system. TDH values of 2.45%, or less than 5%, in the given results are acceptable. The suggested controller was hence appropriate for grid system applications.

Neural adaptive PSD decoupling controller and its application in three-phase electrode adjusting system of submerged arc furnace

Taking three-phase electrode adjusting system of submerged arc furnace as study object which has nonlinear, time-variant, multivariable and strong coupling features, a neural adaptive PSD(proportion, sum and differential) dispersive decoupling controller was developed by combining neural adaptive PSD algorithm with dispersive decoupling network. In this work, the production technology process and control difficulties of submerged arc furnace were simply introduced, the necessity of establishing a neural adaptive PSD dispersive decoupling controller was discussed, the design method and the implementation steps of the controller are expounded in detail, and the block diagram of the controlled system is presented. By comparison with experimental results of the conventional PID controller and the adaptive PSD controller, the decoupling ability, adaptive ability, self-learning ability and robustness of the neural adaptive PSD dispersive decoupling controller have been testified effectively. The controller is applicable to the three-phase electrode adjusting system of submerged arc furnace, and it will play an important role for achieving the power balance of three-phrase electrodes, saving energy and reducing consumption in the process of smelting.

Virtual State Estimation Calculator Model for Three Phase Power System Network

The main objective of this research work is to develop a simple state estimation calculator in LabView for three phase power system network. LabView based state estimation calculator has been chosen as the main platform because it is a user friendly and easy to apply in power systems. This research work is intended to simultaneously acclimate the power system engineers with the utilization of LabView with electrical power systems. This proposed work will discuss about the configuration and the improvement of the intelligent instructional VI （virtual instrument） modules in power systems for state estimation solutions. In the proposed model state estimation has been carried out and model has been developed such that it can accommodate the latest versions of state estimation algorithm.

STUDY ON THE THREE PHASE EQUILIBRIA OF ETHANOL WATER 4A MOLECULAR SIEVE

Vapor liquid solid three phase equilibria of ethanol water 4A molecular sieve system are studied experimentally and theoritically. It is proved that the addition of adsorbent does not change the equilibrium relation between vapor and bulk liquid phase. A calculation procedure is proposed to predict vapor liquid solid (adsorbent) three phase euquilibria.

LOCAL NONLINEAR CHARACTERISTICS OF GAS LIQUID SOLID THREE PHASE SELF ASPIRATED REVERSED FLOW JET LOOP REACTOR

Hursts rescaled range (R/S) analysis and Wolfs attractor reconstruction technique have been adopted to estimate the local fractal dimensions and the local largest Lyapunov exponents in terms of the time series pressure fluctuations obtained from a gas liquid solid three phase self aspirated reversed flow jet loop reactor,respectively.The results indicate that the local fractal dimensions and the local largest Lyapunov exponents in both the jet region and the tubular region inside the draft tube increase with the increase in the jet liquid flowrates and the solid loadings,the local fractal dimension profiles are similar to those of the largest Lyapunov exponent,the local largest lyapunov exponents are positive for all cases,and the flow behavior of such a reactor is chaotic.The local nonlinear characteristic parameters such as the local fractal dimension and the local largest Lyapunov exponent could be applied to further study the flow properties such as the flow regime transitions and flow structures of this three phase jet loop reactor.

DETERMINATION OF EFFECTIVE MODULI FOR FOAM PLASTICS BASED ON THREE PHASE SPHEROIDAL MODEL

The relations of bulk modulus, shear modulus, Young's modulus and the Poisson's ratio with porosity of foam plastics are determined by a three phase spheroidal model commonly used in Composite Mechanics. The results are compared with those using differential scheme. It is shown that the material properties derived from the present model normally are larger than those obtained by differential scheme for foam plastics with identical porosity. The differences in shear moduli and Young's moduli obtained by the two methods are small but they are larger for bulk moduli of incompressible matrix and Poisson's ratios. The Young's moduli of high density foam plastics derived by the present model agree better with experimental ones.

Improved Clamped Diode Based Z-Source Network for Three Phase Induction Motor

The 3Φinduction motor is a broadly used electric machine in industrial applications,which plays a vital role in industries because of having plenty of beneficial impacts like low cost and easiness but the problems like decrease in motor speed due to load,high consumption of current and high ripple occurrence of ripples have reduced its preferences.The ultimate objective of this study is to control change in motor speed due to load variations.An improved Trans Z Source Inverter(ΓZSI)with a clamping diode is employed to maintain constant input voltage,reduce ripples and voltage overshoot.To operate induction motor at rated speed,different controllers are used.The conventional Proportional-Inte-gral(PI)controller suffers from high settling time and maximum peak overshoot.To overcome these limitations,Fractional Order Proportional Integral Derivative(FOPID)controller optimized by Gray Wolf Optimization(GWO)technique is employed to provide better performance by eliminating maximum peak overshoot pro-blems.The proposed speed controller provides good dynamic response and controls the induction motor more effectively.The complete setup is implemented in MATLAB Simulation to verify the simulation results.The proposed approach provides optimal performance with high torque and speed along with less steady state error.

Intelligence Based Soft Starting Scheme for the Three Phase Squirrel Cage Induction Motor with Extinction Angle AC Voltage Controller

Whenever a squirrel cage induction motor is started, notable electromechanical torque and current pulsations occur. The adverse effects of starting torque pulsations and high inrush current in induction motor are eliminated using digital power electronic soft starting schemes that guarantee higher degrees of compliance of the requirements of an ideal soft starter for the induction motor. Soft starters are cheap, simple, reliable and occupy less volume. In this paper, an experimental setup of soft starting technique with extinction angle AC voltage controller and a speed and stator current based closed loop scheme is demonstrated using Artificial Neural Network (ANN) and Fuzzy Logic Control (FLC) by the way of MATLAB/SIMULINK based simulation. The ANN based soft starting scheme produces best results in terms of smooth starting torque and least inrush current. The results thus obtained were satisfactory and promising.

Partial phase relationships of Mg-Zn-Ce system at 350 ℃

The alloys were prepared in Mg-rich corner of Mg-Zn-Ce system. Partial phase equilibrium relationships of these alloys at 350 ℃ were identified by using scanning electron microscopy(SEM), electron probe microanalysis(EPMA), X-ray diffraction(XRD) analysis and selected area electron diffraction(SAED) pattern analysis of transmission electron microscopy(TEM). Partial isothermal section of Mg-Zn-Ce system in Mg-rich corner was identified. The results show that there is one ternary compound (T-phase) in Mg-Zn-Ce system. The T-phase is a linear ternary compound in which the content of Ce is about 7.7% (molar fraction); while the content of Zn is changed from 19.3% to 43.6% (molar fraction). The crystal structure of T-phase is C-centered orthorhombic. In addition, one two-phase region of Mg+T-phase and one three-phase region of Mg+T-phase+MgZn(Ce) exist in the Mg-rich corner of Mg-Zn-Ce system at 350 ℃.

New One-Way Line for Electric Transmission System

There are three well known types of wire lines for transmitting electrical energy or information. The first type is ordinary two wires line （below A-Line）. The second type is so-called single-wire line, where ground plays the role instead of second wire. Polyphase systems belong to the third type, three phase system is the most popular among them. The purpose of this article is another attempt to build a one-wired （without ground） system--the transmission of electrical energy. In this paper an original idea of building such a system is justified, the results of simulations and laboratory modeling are presented. It is shown that the proposed method can reduce the cost of electric transmission lines, the losses in them and significantly reduce interferences.

DC–DC Converter with Pi Controller for BLDC Motor Fuzzy Drive System

The Brushless DC Motor drive systems are used widely with renewable energy resources.The power converter controlling technique increases the performance by novel techniques and algorithms.Conventional approaches are mostly focused on buck converter,Fuzzy logic control with various switching activity.In this proposed research work,the QPSO(Quantum Particle Swarm Optimization algorithm)is used on the switching state of converter from the generation unit of solar module.Through the duty cycle pulse from optimization function,the MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor)of the Boost converter gets switched when BLDC(Brushless Direct Current Motor)motor drive system requires power.Voltage Source three phase inverter and Boost converter is controlled by proportional-integral(PI)controller.Based on the BLDC drive,the load utilized from the solar generating module.Experimental results analyzed every module of the proposed grid system,which are solar generation utilizes the irradiance and temperature depends on this the Photovoltaics(PV)power is generated and the QPSO with Duty cycle switching state is determined.The Boost converter module is boost stage based on generation and load is obtained.Single Ended Primary Inductor Converter(SEPIC)and Zeta converter model is compared with the proposed logic;the proposed boost converter achieves the results.Three phase inverter control,PI,and BLDC motor drive results.Thus the proposed grid model is constructed to obtain the better performance results than most recent literatures.Overall design model is done by using MATLAB/Simulink 2020a.

Hybrid Control Strategy for Matrix Converter Fed Wind Energy Conversion System

In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.

Analysis and improvement of missile three-loop autopilots

The non-minimum phase feature of tail-controlled missile airframes is analyzed. Three selection strategies for desired performance indexes are presented. An acceleration autopilot design methodology based on output feedback and optimization is proposed. Performance and robustness comparisons between the two-loop and classical three-loop topologies are made. Attempts to improve the classical three-loop topology are discussed. Despite the same open-loop structure, the classical three-loop autopilot shows distinct characteristics from a two-loop autopilot with PI compensator. Both the two-loop and three-loop topologies can stabilize a static unstable missile. However, the finite actuator resource is the crucial factor dominating autopilot function.

Triple One Wire System without Grounding

Today the entire globe is shrouded in an inefficient three-phase system. There is however an efficient single-wire system. To use the single wire method, three phase systems can be converted to triple one wire systems.

微纳米颗粒三相泡沫体系构筑及特性

为进一步提高聚驱后采收率,结合聚驱后油藏特征,构筑具有自适应堵调驱功能的微纳米颗粒三相泡沫体系,通过黏度、界面、泡沫和堵调驱性能试验,研究微纳米颗粒三相泡沫体系特性,应用归一化和权重系数方法,分析三相泡沫体系溶液特性与驱油效果的相关性。结果表明:软体微米颗粒三相泡沫体系的特性参数较好,具有超低界面张力,剖面改善率超过82%,聚驱后可提高采收率超过14%;硬质纳米颗粒三相泡沫体系的特性参数相对较差,但聚驱后仍可提高采收率超过10%;三相泡沫体系泡沫综合指数和运动黏度是驱油效果的主要影响因素,而剪切黏度和界面张力是次要影响因素。

基于全扇区统一占空比函数的Ⅰ型NPC三电平SVPWM载波化算法

Ⅰ型中性点钳位(neutral point clamped, NPC)三电平变流器作为中大容量新能源发电系统的核心设备,其调制策略直接影响变流器的能量转换效率、谐波特性和运行控制特性等。鉴于Ⅰ型三电平变流器的传统空间矢量脉宽调制(space vector pulse width modulation, SVPWM)策略在实施过程中包含大量三角函数运算,基于三相静止坐标系进行调制算法的大小扇区判断和矢量作用时间计算等,并通过归纳整理,按照单调制波双载波的载波化思路,获得了适用于全扇区的三相统一的占空比函数。借助该占空比函数,变流器的数字控制器仅需通过简单的关系运算和数值计算,便可获得变流器功率管的控制信号,省去了大量三角函数计算,节约了硬件资源。此外,将SVPWM与正弦波脉宽调制(sinusoidal pulse width modulation, SPWM)+3次谐波注入调制算法进行对比,从调制波层面,揭示了这2种调制算法之间的内在差异。最后,通过仿真验证了该算法的有效性。

基于功率切换模型的三相VSC切换控制方法

三相电压源变换器(voltage source converter,VSC)工作过程可视为在不同开关状态(即不同子系统)下的切换,是一种典型的切换系统。基于切换系统理论,提出一种三相电网平衡条件下基于功率切换模型的三相VSC切换控制策略。相较于传统基于线性化模型的三相VSC控制方法,所提方法具有模型精确无近似,控制参数少,控制器实现简单,无需复杂的坐标旋转变换和脉冲宽度调制过程,对于电路参数不确定具有强鲁棒性等优点。相较于传统基于电流切换模型的三相VSC切换控制策略,所提方法具有模型更便于系统分析与切换规则设计且提升了系统延迟条件下系统稳定性等优点。仿真及实验比较结果证明了所提方法的有效性及优越性。

The Networked Manufacturing Resources Optimizing Configuration System and Its Partners Selection Method

The three levels optimizing strategy is put forward for the networked manufacturing resources optimizing configuration, namely, the optimizing of a logical manufacturing process, the optimizing of simulation-based integration of process planning and scheduling, and the optimizing of networked production scheduling. Then, the web services-based architecture of networked manufacturing resources optimizing configuration is brought forward. Finally, the key algorithm of the networked manufacturing resources optimizing configuration is discussed, namely, the two phases manufacturing partners selection method, which including the group technology-based manufacturing resources pre-configuration and the genetic algorithm-based executable manufacturing process optimizing.

含分布式光伏接入的三相牵引供电系统电压协调控制方法

牵引供电系统中光伏并网逆变器普遍处于弱可控状态且缺乏多机间协调配合,为了使分布式光伏在实现牵引能耗优化的同时,主动参与牵引网电压调控,提出了用于三相牵引供电系统的电压协调控制策略。针对含光伏的新型三相牵引供电系统拓扑,分析了系统电压-有功和无功定量关系。结合分布式光伏无功裕度及协调关系,设计了3阶段分布式电压协调控制策略,根据电压灵敏度判定各节点补偿与削减优先度,实现了分布式光伏无功协调补偿及有功优化削减,达到牵引网电压主动控制。最后,通过对系统多工况下仿真,验证策略有效性。仿真结果表明,所提协调控制策略在三相牵引供电系统复杂的运行工况下,能够在兼顾光伏能量利用率的同时,增强系统电压调控能力,解决牵引网电压越限问题,并有效降低牵引网损耗。研究通过有效利用光伏支撑牵引网电压,为机车的安全、高效运行提供保障。

A Novel Frequency Compensation Technique for Three-Stage Amplifier

A novel frequency compensation technique for three-stage amplifier with dual complex pole-zero (DCP) cancellation is proposed. It uses one pair of complex zeros to cancel one pair of complex poles, resulting in feature that frequency response of the three-stage amplifier exhibits that of a single-pole system. Thus the gain-bandwidth (GBW) is expected to be increased several times compared to the conventional nested miller compensation (NMC) approach. Moreover, this technique requires only one very small compensation capacitor even when driving a big load capacitor. A GBW 4.63 MHz, DC gain 100 dB, PM 90o and power dissipation 0.87 mW can be achieved for a load capacitor 100 pF with a single Miller compensation capacitor 2 pF at a ±1V supply in a standard 0.6-μm CMOS technology.