电力推进系统变压器预充磁仿真与试验研究

本文以舰船交流电力系统中变压器预充磁方法为研究对象,利用多个仿真软件和样机系统对变压器预充磁方法进行验证,总结出舰船交流电力推进系统中变压器预充磁设计的方法和原则,解决大容量变压器的预充磁过程对舰船电力推进系统的冲击问题,对之后的电力推进系统设计提供借鉴。     

船舶电力系统预充磁技术研究

基于船舶电力系统特点,根据大容量变压器空载合闸时励磁涌流的特性,对大容量变压器的预充磁技术进行了深入分析。结合实际变压器参数,讨论了串接小容量变压器预充磁变压器抑制方法,同时讨论了预充磁变压器选取的参考依据,并基于数字仿真进行验证。仿真结果表明:预充磁方案能有效抑制励磁电流的大小,适合应用于船舶电力系统。     

变压器预充磁仿真技术研究

为了有效降低变压器在空载合闸瞬间产生的励磁涌流,本文通过对变压器一次侧串电阻、并联变压器两种预充磁技术进行了仿真分析。同时为了验证所得到的仿真结果是否可信,构建了仿真试验平台。最终证明了所得的仿真结果能够较好的反应实际系统,也说明了变压器在空载合闸时产生的励磁涌流,不但与所选择的预充磁变压器容量有关,还与预充磁变压器接入电网的合闸时间有关。     

预充磁在抑制变压器空载合闸励磁涌流中的作用

本文首先分析了变压器空载合闸时的瞬变过程、变压器励磁涌流形成的机理以及现有的变压器励磁涌流抑制技术,然后阐述了预充磁是通过改变变压器合闸时的初始状态来达到减小变压器励磁涌流的目的,最后利用仿真验证了在原方预充磁可以显著抑制励磁涌流。     

船用变压器励磁涌流及预充磁技术研究

随着大容量变压器在船舶特别是电力推进船舶中的应用,船用变压器励磁涌流问题日渐突出。虽然变压器励磁涌流问题存在已久,但科研人员对励磁涌流的分析、解决多基于陆用大电力系统,对船用变压器励磁涌流而言,其解决方案的研究分析尚不深入。本文基于船舶电力系统特的特殊性,详细叙述了串接小容量变压器预充磁抑制涌流的可行性理论依据,在此基础上建立了变压器励磁涌流及预充磁研究的MATLAB仿真模型,并结合实际工程案例,设计搭建船舶电力系统变压器空载合闸试验平台,对串接小容量变压器预充磁技术进行动模系统物理试验验证。     

电网冲击电流对预充磁变压器的影响分析

船舶大功率推进器等设备在起动时具有较大的起动冲击电流,为了保证大功率设备在启动时,减小电网的波动、防止电站崩溃,因此给这些大型船舶推进器供电的变压器一般选用预充磁变压器;本文基于大型DP2船舶电力系统的特点,结合12,000t抬浮力半潜船在试航期间中压吊舱推进系统预充磁变压器出现的故障现象,进行深入的分析研究,找出问题的关键,为以后船舶电站的设计提供了借鉴经验。     

基于MATLAB的溢油回收船电力推进系统稳态和暂态压降仿真与分析

本文依据万吨级溢油回收船船舶电网设计要求构建满足系统要求的电力系统,并根据相关参数进行电压压降MATLAB仿真,研究和分析船舶电网日常使用和误操作启动大型负载对电网的冲击现象。仿真结果表明,无励磁启动大型负载时电网压降很明显,特别是在网功率不足时压降失真更严重,为避免引起保护开关误动作,需保证预充磁变压器正常投入运行。     

基于预励磁技术的船用变压器励磁涌流控制

在采用中压配电系统的船舶上,通常采用中压/低压变压器实现对低压负载的供电,该变压器的容量相对于船舶电力系统来说很大,当变压器投入运行的时候在变压器原边会产生非常大的浪涌电流,其幅值可达到变压器额定电流的十倍以上,对船舶电力系统的安全运行以及变压器本身造成危害。论文分析了变压器励磁涌流产生的机理和特性,认为涌流是由于变压器空载投入时的饱和特性造成的,分析了采用预充磁技术的涌流抑制原理和方法,并经过仿真和实验对涌流抑制效果进行了验证。     

基于PWM逆变器的船舶变压器励磁涌流消除方法

文章提出了一种消除船舶电力系统中变压器空载合闸过程产生励磁涌流的方法。该方法通过在变压器二次侧接入小容量的电压源逆变器,通过锁相环调节逆变器输出电压,使变压器一次侧绕组输出电压与电网电压的频率、幅值和相位同步,经过预充磁与预同步之后,再使变压器合闸消除励磁涌流。仿真和试验结果验证了所提出的方法能够有效地消除励磁涌流的产生。     

大型船舶变压器预充磁方案研究

本文提出新型大型船舶变压器励磁涌流抑制方案。通过检测大型变压器空载合闸时的负荷电流和电网侧电流,并比较两者的差值,把偏差输入到变压器预充磁装置的控制模块,使控制信号跟踪给定的励磁电流信号,实时调整NPMOT补偿的电流,从而抑制励磁涌流对船舶电力系统的冲击。测试结果表明,新方案能有效抑制励磁涌流,具有实用价值。     

舰船大容量变压器励磁涌流的故障识别

舰船电力系统已经逐步由传统的低压电力系统过渡到中压电力系统,变压器在舰船电力系统中地位和作用也日益凸现,对变压器的保护也日益重要,尤其是在发生短路故障时,迅速可靠的跳闸,是保证变压器安全的重要手段。大容量变压器的内部短路故障主要依靠差动保护,而励磁涌流往往会引起差动保护误动作,因此如何快速识别励磁涌流是确保变压器安全可靠的前提条件。     

基于LabWindows/CVI的船用变压器振动监测系统

振动法是诊断变压器运行中潜伏故障的一种有效手段,应用振动法可以检测出舰船变压器绕组和铁心工作状况,对其进行充分的研究有良好的应用前景.LabWindows/CVI是一个以C语言为基础,结合了测控专业工具的虚拟软件开发平台.应用LabWindows/CVI软件开发了一套船用变压器振动监测系统.经实验分析,该系统能对变压器器身振动信号可有效采集,并进行分析处理.     

推进变压器软启动过程仿真分析

本文通过分析电力变压器的交流励磁原理,建立含饱和特性曲线的电力变压器模型,对变压器空载合闸时的励磁涌流情况进行了仿真和实验。     

船行波对双船系靠LNG泊位系泊稳定性的影响

双船系靠LNG泊位对系泊稳定性要求高,而目前尚无船行波对双船系靠泊稳定性影响的定量分析方法。结合工程实例,以Flory-Remery单船系泊船行波荷载计算方法为基础,结合双船系靠泊位的特点予以修正,利用数值分析软件定量分析船行波过程对双船系靠泊位系泊稳定性的动态影响。结果表明,典型系泊条件下,双船系靠泊位系泊倒缆受力及纵移运动量受船行波影响最大,当船行波与系泊船间距50 m时系泊稳定性不满足要求;当船行波与系泊船间距100 m时系泊稳定性满足要求;当船行波与系泊船间距150 m时系泊稳定性基本不受船行波影响。     

Broaching probability for a ship in irregular stern-quartering waves: theoretical prediction and experimental validation

To avoid stability failure due to the broaching associated with surf riding, the International Maritime Organization (IMO) has begun to develop multilayered intact stability criteria. A theoretical model using deterministic ship dynamics and stochastic wave theory is a candidate for the highest layer of this scheme. To complete the project, experimental validation of the theoretical method for estimating broaching probability in irregular waves is indispensable. We therefore conducted free-running model experiments using a typical twin-propeller and twin-rudder ship in irregular waves. A simulation model of coupled surge–sway–yaw–roll motion was simultaneously refined. The broaching probability calculated by the theoretical method was within the 95 % confidence interval of that obtained from the experimental data. This could be an example of experimental validation of the theoretical method for estimating the broaching probability when a ship meets a wave.     

Fully three-dimensional ship seakeeping computations with a surge-corrected Rankine panel method

A 3-d seakeeping code uses first-order Rankine panels with special numerical integration on the ship's hull and Rankine point source clusters above the free surface. The code computes the motions of the ship in regular waves of small height (linearized). The steady flow is captured without simplification by solving the fully nonlinear wave-resistance problem first. A special treatment of the surge motion considers the influence of periodic quantities on thrust and resistance, and improves surge motion predictions. Radiation and open-boundary conditions are enforced by staggered grids. Results for the ITTC standard test case S-175 containership agree well with experiments except for very long waves. The importance of capturing the three-dimensional steady flow contributions is also demonstrated.     

基于三维解析法的船舶碰撞外部动力学研究

目前国际上船舶碰撞外部动力学的解析法研究均局限于船体碰撞运动的二维假设,忽略了可能存在的大幅横摇。依据文献[1]给出的二维船舶碰撞数学模型,建立了包括横移、纵移、首摇和横摇在内的三维船舶碰撞数学模型,并编制程序对文献[2]中的算例进行计算,计算结果表明船舶横摇运动在大多数船舶碰撞情况下是不可忽略的。     

Analytical formulae for predicting the surf-riding threshold for a ship in following seas

Making use of Melnikov’s method, a generalized formula for predicting the surf-riding threshold is developed as an extension to the applications of Kan and Spyrou. A new analytical formula for calculating the surf-riding threshold of a ship in following seas is also proposed in light of nonlinear dynamical system theory. By applying a continuous piecewise linear approximation to the wave-induced surge force, a heteroclinic bifurcation point is obtained analytically with an uncoupled surge equation. Results calculated using these formulae are presented, and they show good agreement with those obtained utilizing numerical bifurcation analysis. Further, it was confirmed that the surf-riding threshold obtained using the proposed formulae agrees reasonably well with that obtained experimentally for an unconventional vessel.     

山体滑坡海事风险的三维测度方法

为了更科学地评判山体滑坡灾害导致的海事风险并且科学实施水上交通管制决策,研究山体滑坡海事风险的三维测度方法。以大中规模剧动式滑坡涌浪为研究对象,根据山体滑坡海事风险的形成过程研究其海事风险的三维测度方法,提出了以山体滑坡变形破坏阶段、滑坡涌浪规模、涌浪损毁船舶的系统风险综合系数为测度指标的海事风险评判模型,并通过实例说明该方法及风险评判模型的应用。研究结论表明:该海事风险测度方法及评判模型,考虑了山体滑坡险情水上交通管制的主要因素,全面地反映了山体滑坡灾害导致的海事风险特征。     

Circular motion tests and uncertainty analysis for ship maneuverability

Circular motion test data and uncertainty analysis results of investigations of the hydrodynamic characteristics of ship maneuvering are presented. The model ships used were a container ship and two tankers, and the measured items were the surge and sway forces, yaw moment, propeller thrust, rudder normal and tangential forces, pitch and roll angles, and heave. The test parameters were the oblique angle and yaw rate for the conditions of a hull with a rudder and propeller in which the rudder angle was set to zero and the propeller speed was set to the model self-propulsion conditions. Carriage data showing the accuracy of the towing conditions in the circular motion test are also presented. It was confirmed that the uncertainties in the hydrodynamic forces such as the surge and sway forces, yaw moment, rudder tangential and normal forces, and propeller thrust were fairly small. The reported uncertainty analysis results of the circular motion test data may be beneficial in validating data quality and in discussing reliability for simulation of ship maneuvering performance.