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。

IoT Enabled Microgrid Framework Using a Novel Dispersal Diffusion Artificial Neural Network Controller for PV Systems and Wind Energy to Minimize Electrical Faults

A system based on a PV-Wind will ensure better efficiency and flexibility using lower energy production.Today,plenty of work is being focussed on Doubly Fed Induction Generators(DFIG)utilized in wind energy systems.DFIG is found to be the best option in the Wind Energy Conversion Systems(WECS)to mitigate the issues caused by power converters.In this work,a new Artificial Neural Network(ANN)is proposed with the Diffusion and Dispersal strategy that works on Maximum Power Point Tracking(MPPT)along with Wind Energy Conversion System(WECS)to minimize electrical faults.The controller focus was not just to increase performance but also to reduce damage owing to any phase to phase fault or Phase to phase to ground fault.To ensure optimal MPPT for the proposed WECS,ANN achieves the optimal PI controller parameters for the indirect control of active and reactive power of DFIG.The optimal allocation and size of the DGs within the distributed system and for MPPT control are obtained using a population of agents.The generated solutions are evaluated and on being successful,the agents test their hypothesis again to create a positive feedback mechanism.Simulations are carried out,and the proposed IoT framework efficiency indicates performance improvement and faster recovery against faults by 9 percent for phase to ground fault and by 7.35 percent for phase to phase fault.

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。

Scheduling and control co-design for Networked Wind Energy Conversion Systems

Fieldbus, industrial Ethernet that is simple, reliable, economical, and practical, is widely used in Wind Energy Conversion Systems(WECSs). These techniques belong to the field of networked control systems. Network embedding to Wind Energy Conversion Systems brings many new challenges. Implementing a control system over a communication network causes inevitable time delays that may degrade performance and can even cause instability. This work addresses challenges related to the reliable control of wind energy conversion systems, based on the theoretical framework of networked control systems. A type of WECS with network-induced delay and packet dropout is modeled and adjustable deadbands are explored as a solution to reduce network traffic in WECSs. A method to study the reliable control of WECSs is presented, which takes into account system response as well as the network environment. After detailed theoretical analysis, simulation results are provided, which further demonstrate the feasibility of the proposed scheme.

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.

Event-triggered mechanism based robust fault-tolerant control for networked wind energy conversion system

In this paper,a novel robust fault-tolerant control scheme based on event-triggered communication mechanism for a variable-speed wind energy conversion system(WECS)with sensor and actuator failures is proposed.The nonlinear WECS with event-triggered mechanism is modeled based on the Takagi-Sugeno(T-S)fuzzy model.By Lyapunov stability theory,the parameter expression of the proposed robust fault-tolerant controller with event-triggered mechanisms is proposed based on a feasible solution of linear matrix inequalities.Compared with the existing WECS fault-tolerant control methods,the proposed scheme significantly reduces the pressure of network packet transmission and improves the robustness and reliability of the WECS.Considering a doubly-fed variable speed constant frequency wind turbine,the eventtriggered mechanism based fault-tolerant control for WECS is analyzed considering system model uncertainty.Numerical simulation results demonstrate that the proposed scheme is feasible and effective.

Optimal control of oscillation wave energy system using velocity premonition

Recently ocean wave energy draw much more attention for its widespread,abundant and highly energy flux density properties.Extracting energy from incident wave however,is limited for the random and unstable power input.Motion control for WEC is a promising method to improve the energy absorption and some practical applications are also verified such as latching control.In this paper,an active control strategy is proposed to achieve maximum energy capture.The mathematical description shows that the active control has the characteristic of anti-causal and the wave premonition is necessary for controller design.But the fact of premonition time horizon is still unclear.In this paper,the premonition nature is described mathematically based on hydrodynamic theory.Furthermore,a simulation is also performed to study the impacting of premonition time horizon on WEC's properties and give a more insightful understanding of WEC active control.

Control of Doubly Fed Induction Generator Supplied via Matrix Converter for Wind Energy Conversion System

The present paper deals with the modeling and control of Wind Energy Conversion System WECS based Doubly Fed Induction Generator DFIG using the slip energy recovery principle. The proposed drive system uses a Matrix Converter (MC) to transfer the slip energy of the rotor into the mains instead of using cascaded ac-dc-ac converter whilst the stator side is fixed to the grid. Operation at both sub-synchronous and super-synchronous regions is possible with the proposed drive system. The different level control strategies for maximum power point tracking and active-reactive power are discussed. Simulation results of the proposed doubly fed induction generator drive system show the good performance of the control system strategy for both transient and steadystate conditions.

Ultra-Modified Control Algorithms for Matrix Converter in Wind Energy System

This paper proposes an ultra-modified SSA(symmetric sequence algorithm)of space vector modulation of MC(matrix converter).The ultra-modified technique improves the drawbacks of the modified one where it provides a reduction of the total harmonic distortion for both output voltage and current.Also this paper proposes a modified feed forward controller of the MC with indirect space vector modulation.The modified feed forward provides a solution for the change in the output voltage due to change in wind speed,where it provides a constant output voltage with constant frequency even if the wind speed changed.Some of the advantages of MC are introduced in this paper.These advantages represented in the output frequency of MC which may be greater than the input frequency,controlling rms value of the output voltage and the ability to control the IDF(input displacement factor).At the end of this paper simulation and experimental results are introduced which give a precise proof to the proposed algorithms.

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。

Development of OIST Wave Energy Converter Monitoring System for Maldives Island Experiment

This paper describes experiments with our self-built Wave Energy Convertor(WEC)monitoring system in the Maldives and demonstrates how we developed a horizontal-axis type,half-scale,wave energy converter(WEC)that generates electricity in the coastal breaking wave zone.In order to measure this power generator and turbine’s efficiency,voltage and current were measured by pulling the generator with a 35 cm diameter turbine(half scale).We obtained data showing 400 W peak power in water speed of 3.1 m/s.Consequently,we assembled two sets of WEC,placed them near the shoreline on Kandooma Island in the Maldives in May 2018,and measured the wave energy at the breaking wave zone.A monitoring system was set up in one rack for the two sets of WECs,connected simultaneously.Two outputs of the generators were rectified and connected to power resistors and internal LED displays.The outputs could also be switched to connect to 24 electric double layer capacitors(EDLC),in order to perform a continuous lighting test of external high-power LED lights.The wave power data were continuously saved by an automated data logger and could be transferred from the installation site,to Japan via the Internet.The wave power was measured on Kandooma Island in the Maldives for a long period,and is still ongoing.Examples of the obtained data are shown in this paper.

弹性胶囊振荡水柱式波能转换装置的水动力特性研究

波浪能是一种极具潜力的可再生能源。为推进波能资源的利用,开发具有应用前景的新型波能转换装置(WEC),提出了创新性的弹性胶囊振荡水柱式(EC-OWC)波能转换装置,设计建立了物理试验模型。通过膨胀波试验,研究了弹性胶囊的膨胀特性和自由膨胀波的运动特性;通过波浪试验,研究了装置与波浪耦合作用时的水动力性能,以及波浪和模型参数对系统振荡和波高放大比的影响。结果显示:装置内外水头差由0增加至30 cm时,自由膨胀波波速由约3.02 m/s减小至1.90 m/s,与一维纵波理论结果规律相符;相对水深在0.0644~0.0782范围内时,稳定后的波高放大比基本均超过4,其中相对水深值为0.0706时达到最大波高放大比6;波高放大比随相对水头的增大先增大后减小,相对水头值为6时达到最大波高放大比6.5;波高放大比在相对管长为1.77时达到最大值6.35。结果表明:一维纵波理论可为弹性胶囊的设计提供支撑;控制水头差可有效调整装置的自然振荡周期;当装置内外振荡周期相匹配时,系统达到近似共振,装置内部膨胀波为驻波,且当胶囊长度接近半波长时,波高放大比达到最大。通过对EC-OWC模型的初步水动力性能试验研究,展示了该装置的优越性能和共振特性,可为此类WEC的开发提供参考。

基于改进蜜獾算法的波能转换器阵列优化

针对波浪能转换器(WEC)阵列发电效率提升问题,提出一种基于改进蜜獾算法的三系WEC阵列优化方法.首先,为克服原始蜜獾算法(HBA)收敛速度慢、收敛精度低等缺陷,引入佳点集初始化、混沌机制和蜜獾种群变异3种策略对原始HBA进行改进.此外,为了验证改进蜜獾算法(IHBA)的先进性和有效性,开展2个浮标、10个浮标和20个浮标3个不同规模的WEC阵列优化实验.2浮标阵列仿真结果表明,WEC阵列优化存在多组最优解,且IHBA、HBA、遗传算法和粒子群优化算法都能以不同速度找到最优解.然而,随着WEC阵列规模的增大,3种对比算法都会陷入局部最优解.相反地,IHBA依然表现出较强寻优能力并能搜寻到全局最优解.最后,IHBA所获10浮标和20浮标的阵列q因子分别高达1.059和0.968,远优于其他3种算法.

一种串联式双浮体直驱式波浪发电系统的设计与试验研究

针对传统的直驱式波浪发电系统安装不便以及俘获波浪能能力弱的问题,文章提出了一种漂浮串联式双浮体直驱式波浪发电系统。该系统的两个浮体水平漂浮在波浪中,Halbach永磁直线发电机的初级与次级分别安装在两个浮体之间的侧面,两个浮体均可俘获波浪能,提升了系统的波浪能俘获能力。该系统还具有结构简单、易于制造与维护的优点。文章利用制作的原型样机在波浪水槽中进行了试验。试验结果表明,在波高为16 cm,浮体吃水为16 cm,在波浪周期从1.2 s增大到2.4 s的波况下,原型样机的平均发电功率在1.8 s处取得最大值6.54 W。比较双浮体原型样机与单浮体样机后发现,在波浪周期较大的范围内,双浮体原型样机输出的平均发电功率一直高于单浮体样机。

浅水波浪能平台弹性浮筒系泊系统自存研究

针对波浪能发电平台布置海域水深浅、台风多发、珊瑚礁地质地基承载力低的特点,以“南鲲号”鹰式波浪能平台为研究对象开展低载荷浅水锚泊系统方案设计和动力学分析研究。通过对全锚链、弹性索与弹性索+浮筒3种不同方案的对比研究发现:相较于全锚链系泊方案,高弹性非线性材料的添加可有效降低系泊张力、起锚力与水平载荷,但会增大平台运动范围;弹性材料与浮筒的联合应用则可在进一步降低系泊系统载荷的同时,限制平台运动范围。在满足经济安全需求基础上,弹性索+浮筒系泊方案在适应浅水恶劣环境方面有着良好预期。

阵列式直驱波浪发电系统集中式模型预测控制方法

将多个波浪能发电装置组成阵列是大规模开发波浪能的发展趋势。对于阵列式直驱波浪发电系统,采取合适的能量优化控制方法能显著提升波浪能捕获效率。然而,由于阵列式系统存在浮子间的相互辐射作用,已有的集中式模型预测控制(MPC)面临在线计算量大、难以工程应用的困难,而将各浮子视作独立系统的分布式MPC则存在能量捕获效率的损失。对此,文中提出一种改进的集中式MPC方法,将优化区间与约束区间进行解耦,可在保障系统整体能量捕获效率的同时,大幅减少计算开销,提升系统的实时控制性能。通过仿真研究分析了约束区间解耦方法的性能,并在多种波浪工况条件下验证了所提出方法的有效性。

基于联合仿真的波浪能发电装置PTO系统参数优化研究

PTO(power take-off)系统是波浪能发电装置(wave energy converter,WEC)的重要组成部分。本文针对摇臂式波浪能发电装置,提出一种机械式PTO系统,考虑发电机负载与机械传动的影响,开展摇臂浮子水动力性能与PTO系统的联合仿真研究。分析摇臂浮子在不同行程工作模式下的运动响应,并对联合仿真模型的PTO系统参数进行优化。研究发现:在目标海况下,本项目设计的发电装置,双行程工作的WEC系统功率显著高于单行程工作状态,双行程WEC最佳功率对应的传动比约为72.5;单行程工作的摇臂浮子在低传动比(小于60)下的上升、下降功率近乎相等,随着传动比的增加,上升、下降行程的功率相较于双行程模式都分别递增,且下降行程功率大于上升行程功率。本文采用的联合仿真方法可为不同海况与各类振荡浮子式波能发电装置的设计与选型提供参考。