基于PMSG-WECS的双自适应虚拟惯性控制方法研究

基于提高电网的频率响应能力的目的,该文提出了一种基于永磁同步发电机(PMSG)的风力发电系统的双自适应虚拟惯性控制方法。通常情况下,采用虚拟惯性常数来模拟同步发电机,其释放的能量完全依赖于频率变化率(ROCOF)。然而,仅依赖于ROCOF并不能充分利用风机的惯性。为了获得更好的系统频率响应,该方法充分利用风力发电机(WT)的转子动能和风力发电系统(WECS)的直流链电容能量作为系统频率的支撑,并根据电网频率和电网频率变化率(ROCOF)自适应调节虚拟惯性参数,加速系统频率的恢复过程。通过仿真分析可知,提出的控制方法能更有效地利用风机动能和直流链电容的能量,减小了频率偏差和频率变化率。

不平衡电网电压下基于无模型自适应控制的WECS控制研究

不平衡电网电压会影响风能转换系统(WECS)的正常并网运行,导致系统输出功率的波动以及输出电流的畸变。此外,在实际的永磁同步风电系统中可能会由于环境温度的变化以及检测误差等原因使得网侧电路参数存在不确定性的问题,如果参数发生改变,传统控制方法的性能将会下降。基于此,提出了一种基于灰色预测的无模型自适应控制(MFAC)方案,以缓解因电路参数不确定性导致的性能下降问题,使控制系统具有更好的抗干扰能力。此外,采用三种独立的控制方法来解决不平衡电网电压下并网输出功率的波动及电流畸变问题。仿真对比结果表明,所提控制策略不仅在电路标称参数下具有良好的静态和动态性能,而且当网侧电感参数变化时,系统的鲁棒性也得到提高,验证了所提方案的优越性。

RT-flex型柴油机的控制系统WECS-9520功能性分析研究

作为船用新一代电喷智能Win GD RT-FLEX系列柴油机,在燃烧性能的不断优化,安全性能的不断提高,新技术和新工艺的应用不断深入,对管理人员的技能水平要求越来越高,本篇主要针对RT-FLEX系列机型的核心控制单元WECS-9520功能性分析研究,WECS-9520是柴油机控制的核心,本篇对WECS-9520控制系统的组成,外部系统的通信以及功能性设计等进行了全面的分析,拟帮助船舶工作人员熟悉WECS-9520的控制核心功能,掌握柴油机故障的分析与解决问题的方法,提高柴油机运行的可靠性,确保船舶运营的安全性。

工业循环水WECS改造技术的应用探讨

阐述了酒钢集团不锈钢二期软环泵站引进的改造技术——工业循环水系统节能优化运行技术(Water Energy Conservation System,WECS),在对冷却循环水系统进行WECS改造后,系统节能率达到62%,并在改造后的近两年时间内,一直安全顺利运行。

The Criteria for Reducing Centrally Restricted Three-Body Problem to Two-Body Problem

Our Solar System contains eight planets and their respective natural satellites excepting the inner two planets Mercury and Venus. A satellite hosted by a given Planet is well protected by the gravitational pertubation of much heavier planets such as Jupiter and Saturn if the natural satellite lies deep inside the respective host Planet Hill sphere. Each planet has a Hill radius aH and planet mean radius RP and the ratio R1=RP/aH. Under very low R1 (less than 0.006) the approximation of CRTBP (centrally restricted three-body problem) to two-body problem is valid and planet has spacious Hill lobe to capture a satellite and retain it. This ensures a high probability of capture of natural satellite by the given planet and Sun’s perturbation on Planet-Satellite binary can be neglected. This is the case with Earth, Mars, Jupiter, Saturn, Neptune and Uranus. But Mercury and Venus has R1=RP/aH =0.01 and 5.9862 × 10-3 respectively hence they have no satellites. There is a limit to the dimension of the captured body. It must be a much smaller body both dimensionally as well masswise. The qantitative limit is a subject of an independent study.

应用WEC技术通过时间效应关系研究氟的发育毒性

应用WEC技术,氟浓度为30μg/ml对妊娠9.5天龄大鼠的胚胎在体外进行不同时间的染毒观察氟对胚胎生长发育和形态分化影响的时间效应关系。结果显示,氟对大鼠胚胎生长发育和器官形态分化均有明显的抑制作用,暴露起始越早,持续时间越长,抑制效应越强,表现出明显的时间效应关系。暴露时间16小时已明显抑制卵黄囊血管分化和血管网形成。24小时以上各实验组,反映胚胎生长发育和形态分化的各项指标与对照比较均呈现出显著差异(P<0.05;P<0.01)。胚胎畸形发生率也显著升高。

Performance of Two Types of Mooring Systems in the Heave Motion of a Two-body Floating Wave Energy Converter

This work investigated the influence of two types of mooring systems on the hydrodynamic performance of a two-body floating wave energy converter(WEC). It also investigated the effects of the physical parameters of the mooring system on the amount of extractable power from incident waves in the frequency domain. The modeled converter comprised a floating body(a buoy), a submerged body with two mooring systems, and a coupling system for two bodies. The coupling system was a simplified power take-off system that was modeled by a linear spring-damper model. The tension leg mooring system could drastically affect the heave motion of the submerged body of the model and increase relative displacement between the two bodies. The effects of the stiffness parameter of the mooring system on power absorption exceeded those of the pretension tendon force.

Microstructure, mechanical properties and two-body abrasive wear behaviour of hypereutectic Al-Si-SiC composite

The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investigated.The hypereutectic Al-Si-Si C composite was prepared by stir casting route.The hardness,ultimate tensile strength and yield strength of the composite are increased by 17%,38%,and 30%respectively compared with those of the matrix alloy,while the elongation of the composite is decreased by 48%compared with that of the matrix alloy.The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance.The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy(HR FESEM)and wear mechanism was analyzed for low and high load regimes.

Parametric Study of Two-Body Floating-Point Wave Absorber

In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber （FPA） with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter＇s efficiency when considering specific conditions.

INVESTIGATION ON TWO-BODY WEAR OF AUSTENITIC MANGANESE STEEL THROUGH NUMERICAL QUADRATURE

The mathematic calculation on two--body wear of austenitic manganese steel has been performed by means of the elastic contact theory,stress interferometer and SEM.Stress distribution in contacted area was calculated and the mechanism on two--body wear has been investigated through numerical quadrature.Results show that two--body wear is mainly plowing wear the cracks of abrasive dust originates from the region between 0.2αand 0.5α(αis radius of contacted round).Driving force to make crack extension along y axis is T_(yzmax)and extension direction is 45°with horizon.Driving forces to make crack extension along x axis is alternativeσ_x and T_(yzmax),the direction of crack extension is 37°with horizon.

On the Gravitational Two-Body System and an Infinite Set of Laplace-Runge-Lenz Vectors

The current approach of a system of two bodies that interact through a gravitational force goes beyond the familiar expositions [1-3] and derives some interesting features and laws that are overlooked. A new expression for the angular momentum of a system in terms of the angular momenta of its parts is deduced. It is shown that the characteristics of the relative motion depend on the system’s total mass, whereas the characteristics of the individual motions depend on the masses of the two bodies. The reduced energy and angular momentum densities are constants of motion that do not depend on the distribution of the total mass between the two bodies;whereas the energy may vary in absolute value from an infinitesimal to a maximum value which occurs when the two bodies are of equal masses. In correspondence with infinite possible ways to describe the absolute rotational positioning of a two body system, an infinite set of Laplace-Runge-Lenz vectors (LRL) are constructed, all fixing a unique orientation of the orbit relative to the fixed stars. The common expression of LRV vector is an approximation of the actual one. The conditions for nested and intersecting individual orbits of the two bodies are specified. As far as we know, and apart from the law of periods, the laws of equivalent orbits concerning their associated periods, areal velocities, angular velocities, velocities, energies, as well as, the law of total angular momentum, were never considered before.

Re-examination of the Two-Body Problem Using Our New General System Theory

It is well-known that philosophical conflicts exist among classical mechanics,quantum mechanics and relativistic mechanics.In order to use the framework of general system theory to unify these three mechanics subjects,a new general system theory is developed based on a new ontology of ether and minds as the fundamental existences in the world.The two-body problem is the simplest model in mechanics and in this paper,it is re-examined by using our new general system theory.It is found that the current description of the classical full two-body problem is inappropriate since the observer and the measurement apparatus have not been explicitly considered.After considering these,it is actually a three-body problem while only the special case of the Kepler problem is the two-body problem.By introducing the concepts of psychic force and psychic field,all the possible movement states in the two-body problem can be explained within the framework of classical mechanics.There is no need to change the meanings of many fundamental concepts,such as time,space,matter,mass,and energy as done in quantum mechanics and relativity theory.This points out a new direction for the unification of different theories.

Topological quantum-phase coherence in full counting statistics of transport electrons with two-body interaction

The full counting statistics of electron transport through two parallel quantum dots with antiparallel magnetic fluxes is investigated as a probe to detect the topological quantum-phase coherence （TQPC）, which results in the characteristic oscillation of the zero-frequency cumulants including the shot noise and skewness. We show explicitly the phase transition of cumulant spectrum-patterns induced by the topology change of electron path-loops while the pattern period, which depends only on the topology （or Chern number）, is robust against the variation of Coulomb interaction and interdot coupling strengths. Most importantly we report for the first time on a new type of TQPC, which is generated by the two- particle interaction and does not exist in the single-particle wave function interference. Moreover, the accurately quantized peaks of Fano-factor spectrum, which characterize the super- and sub-Poissonian shot noises, are of fundamental importance in technical applications similar to the superconducting quantum interference device.

GENERALIZED HOMOGENEOUS FUNCTIONS AND THE TWO-BODY PROBLEM

A generalization of the homogeneous function concept is studied.An application is done with a solution of the two-body problem.

Power Absorption of A Two-Body Heaving Wave Energy Converter Considering Different Control and Power Take-off Systems

This study proposed a wave power system with two coaxial floating cylinders of different diameters and drafts.Wavebob’s conceptual design has been adopted in the wave power system.In this study,a basic analysis of the wave energy extraction by the relative motion between two floats is presented.The maximum power absorption was studied theoretically under regular wave conditions,and the effects of both linear and constant damping forces on the power take-off(PTO)were investigated.A set of dynamic equations describing the floats’displacement under regular waves and different PTOs are established.A time-domain numerical model is developed,considering the PTO parameter and viscous damping,and the optimal PTO damping and output power are obtained.With the analysis of estimating the maximum power absorption,a new estimation method called Power Capture Function(PCF)is proposed and constructed,which can be used to predict the power capture under both linear and constant PTO forces.Based on this,energy extraction is analyzed and optimized.Finally,the performance characteristics of the two-body power system are concluded.

Modeling of Adhesive Particles Using a Combination of the Two-Body Interaction and Phase-Field Methods

Discrete materials such as powders and granular materials have been widely used due to their specific characteristics. The precise evaluation is accordingly becoming important, and various numerical schemes have been developed. However, the interactions among the constituent particles are still difficult to model precisely. Especially, contact conditions, which vary with material properties and circumstances, are difficult to formulate. In this study, a computational model for simulating adhesive particles on contact in a many-particle system is proposed. The interaction between the particles was represented by a two-body repulsive force that depends on the distance between particles and an additional adhesive force at the contact point. A phase-field variable was introduced to express the surface of each particle, and the adhesive force was formulated using the phase-field distribution. As a result, the adhesion of particles was properly expressed. For a mono-particle system, neighboring particles adhered and uniformly aggregated, while for a dual-particle system, several characteristic patterns were obtained depending on the initial arrangement of the particles. Repulsive contact was also considered as a specific case, and the corresponding results were obtained.

Approximate and Exact GR-Solutions for the Two-Body Problem

A binary gravitational rotator, also called the two-body problem, is a pair of masses m1, m2 moving around their center-of-mass (com) in their own gravitational field. In Newtonian gravitation, the two-body problem can be described by a single reduced mass (gravitational rotator) mr = m1m2/(m1+m2) orbiting around the total mass m = m1+m2 situated in com in the distance r, which is the distance between the two original masses. In this paper, we discuss the rotator in Newtonian, Schwarzschild and Kerr spacetime context. We formulate the corresponding Kerr orbit equations, and adapt the Kerr rotational parameter to the Newtonian correction of the rotator potential. We present a vacuum solution of Einstein equations (Manko-Ruiz), which is a generalized Kerr spacetime with five parameters gμν (m1, m2, R, a1, a2), and adapt it to the Newtonian correction for observer orbits. We show that the Manko-Ruiz metric is the exact solution of the GR-two-body problem (i.e. GR-rotator) and express the orbit energy and angular momentum in terms of the 5 parameters. We calculate and discuss Manko-Ruiz rotator orbits in their own field, and present numerical results for two examples. Finally, we carry out numerical calculations of observer orbits in the rotator field for all involved models and compare them.

基于传递函数分析的双馈风力发电系统动态建模方法研究

以双馈风力发电系统(doubly-fed induction generator based wind energy conversion system,DFIG-based WECS)为例,利用小信号分析法推导出由风机、双质量块传动链构成的动力与传动系统通用传递函数方程。动力与传动系统传递函数的零极点位置、稳定性与系统参数及系统运行工作点相关。该传递函数可进一步分解为扭转分量和非扭转分量。传动链参数仅对扭转分量造成影响。在此基础上,建立了考虑动力传动、电机、变流器、控制等环节的风力发电系统传递函数模型。模型综合了各环节参数,可直观反映系统参数对系统响应的影响,有助于深入了解系统动态行为。算例及时域仿真结果证明了所提出传递函数模型的准确性和高效性,可为系统参数设计研究提供理论依据。

雨战WEC世界耐力锦标赛

说来也怪，歌迷和球迷都会因为偶像或是支持的球队的比赛而欢呼雀跃，一票难求的盛况比比皆是。而车迷们似乎就对现场这个东西不是那么感兴趣，更何况是这种战事持续长达6个小时的耐力赛。但是当我得知这次可以和车队一起在P房里观战的时候，激动之情堪比JasonMraz来我家门口的广场上开演唱会。

WEC:全球水电发展势头迅猛

据世界能源理事会（简称WEC）最近发表的报告称,近年来,全球水电领域发展势头迅猛,2004年与当前相比,全球水电装机容量涨幅达到了27%左右。据报告显示,2013年,水电占全球电力供应的比例为16.4%,全球水电已建成装机容量达1000吉瓦,仅2013年就建成了约40吉瓦。尽管如此,水电每年还有高达10000太瓦时的电量可以开发,可见水电开发尚存在巨大潜力。