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。

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。

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。

Drive-train torsional vibration suppression of large scale PMSG-based WECS

This paper provides a systematic analysis of the large scale PMsG(permanent magnet synchronous generator)-based WECS(wind energy conversion system)torsional vibration problem under MPPT(maximum power point tracking)control and constant power control.This is from the perspective of SSo(sub-synchronous oscillation),SSH(sub-syn-chronous harmonics)and forced torsional vibration.The cause of SsO is the negative total system damping,weak-ened by the constant power control.The system is susceptible to inducing SSH in the grid current and voltage in the under-damped condition.To effectively suppress the torsional vibration of PMSG-based WECS,a stiffness compensa-tion control strategy based on adaptive damping is proposed.The results show that SSo,SSH and the forced torsional vibration can be suppressed at the source using the proposed suppression strategy.

风力发电机组的非线性控制——变结构控制与鲁棒控制

风速、风向及负载的随机性、湍流、尾流效应、塔影效应等的影响,使风力发电系统不但要解决最大风能捕获、电能品质控制两类关键问题,还要解决传动链的疲劳负载、叶片的振颤与翦切、塔身的弯曲与抖振等问题,这些问题实际上都可归结为非线性控制的范畴。该文综述了近年来滑模变结构控制、H∞鲁棒控制在风力发电系统稳定,最大风能捕获及调速系统控制等方面应用研究的主要成果与方法,并提出若干需要解决的问题。

直流纳电网技术在波能装置群中的应用

根据波能装置液压发电系统的特性,提出由蓄电池组支撑的直流纳电网技术。波能装置群采用直流并网与传输,可以接受周期波动的波浪能功率,效率、可靠性、电能质量均较高。纳电网蓄电池可解除波能装置群发电功率与纳电网逆变器的馈网功率,各装置负载可简化为纳电网蓄电池,各装置分别向蓄电池充电,互不影响。纳电网逆变器为海岛居民提供稳定的高质量的可控电源。仿真和实践证明波能装置群应用直流纳电网技术的可行性和优势。

浅析RT-flex系列船用智能柴油机网络监控技术

随着船舶主机新技术的不断发展,越来越多的智能柴油机在船舶上得以应用。针对智能柴油机维护管理困难的新问题,以Sulzer RT-flex系列船用智能柴油机为例,对其网络监控及AutoChiefC20主机遥控系统的网络集成技术进行分析,并提出维护管理建议,对船舶轮机、电气管理人员具有一定的参考意义。

PWM逆变器的定向矢量控制策略

针对风力发电并网的优化问题。提出了三相电压源脉冲宽度调制(PWM)逆变器的定向矢量控制技术,并设计了数字控制的变换器-逆变器系统。给出了该变换器和逆变器的数学模型。提出了一种定向矢量控制的方案来实现对风能并网的控制策略。为了检验该系统的动态性能,采用MATLAB7/SIMULINK程序进行了仿真。仿真结果表明,提出的控制系统模型在不同的干扰下都展现出其良好的性能。

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.

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。

化工流程循环水系统节能改造技术的应用探讨

循环冷却水系统是化工企业中一项常见且很重要的公用工程,但普遍存在运行效率低下、能耗居高不下等问题,该文简单介绍浙江巴陵恒逸己内酰胺有限责任公司循环水系统节能改造情况,以及所采用的改造技术—工业循环水系统节能优化运行技术(WECS),旨在为行业内的类似系统节能提供参考。

WARTSILA RT-flex柴油机喷油控制系统流量活塞卡死故障分析

近年来,电喷二冲程柴油机由于其具有低速稳定性好,燃油雾化效果好,调控方便等优点在船舶上获得了普遍应用。但由于电喷柴油机内部含有大量的电子控制系统,这对于故障的定位及维修也带来了巨大的挑战。本文详细分析了WARTSILA RT-flex型柴油机的瓦锡兰柴油机控制系统(WECS),并结合具体的故障案例,对其中的喷射控制系统(ICU:Injection Control Unit)故障进行诊断与维修。通过分析故障缸的燃油喷射参数,发现流量活塞的return电流出现异常,经过测量部件内部阻值判断是由于FQS与遮蔽铝管的位置发生改变引起的内部阻值变化,推断可能是ICU控制系统中流量活塞发生卡死现象导致内部阻值的异常,引发return电流的异常。经过后期进一步测量,得出故障原因是由于活塞头部椭圆度过大而产生沉头现象,导致套筒内出现椭圆偏磨,使流量活塞卡死,导致喷油异常,排烟温度异常。本论文对于深入探讨WECS控制系统以及喷射控制单元的工作过程,对其故障维修具有一定的借鉴意义。

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.

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.

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.

New Robust Energy Management Model for Interconnected Power Networks Using Petri Nets Approach

The problematic of energy management, particularly in terms of resources control and efficiency, has become in the space of a few years an eminently strategic subject. Its implementation is both complex and exciting as the prospects are promising, especially in relation with smart grids technologies. The deregulation of the electricity market, the high cost of storage, and the new laws on energy transition incite some significant users (collectivities, cities, regions, etc.) to form themselves into local producers in order to gain autonomy and reduce their energy bills. Thus, they may have their own sources (classic and/or renewable energy sources) to satisfy their needs and sell their excess production instead of storing it. In this idea, the territorial interconnection principle offers several advantages (energy efficiency, environmental protection, better economic balance). The main challenge of such systems is to ensure good energy management. Therefore, power distribution strategy must be implemented by matching the supply and the demand. Such systems have to be financially viable and environmentally sustainable. This allows among others to reduce the electricity bill and limit the systematic use of the national power network, typically using non-renewable sources, and thereby support sustainable development. This paper presents an original model for aid-decision in terms of grid configurations and control powers exchanged between interconnected territories. The model is based on Petri nets. Therefore, an iterative algorithm for power flow management is based on instantaneous gap between the production capability (photovoltaic, wind) and the demand of each user. So, in order to validate our model, we selected three French regions: the PACA region, the Champagne-Ardenne region and the Lorraine region. Due to their policy, their geographical and climatic features, we opted for two renewable sources: “wind” and “photovoltaic”. The numerical simulations are performed using the instantaneous productions of each region and their energy demand for a typical summer day. A detailed economic analysis is performed for two scenarios (with or without interconnections). The results show that the use of renewable energy in an interconnection context (i.e. pooling), offers serious economic and technical advantages.

RT-flex主机的应用及特殊电气故障的排除

主机试验是船舶系泊试验中最重要的试验之一,在实验及调试过程中出现的问题也很特殊,解决并处理好这些问题对于船舶的系泊及航行试验的顺利进行起着至关重要的作用.总结了RT-flex电喷系列主机在试验现场发现的电气问题及解决的方案,供技术人员参考.

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.

Oscillation and Conversion Performance of Double-Float Wave Energy Converter

In this study, we investigated the hydrodynamic and energy conversion performance of a double-float wave energy converter(WEC) based on the linear theory of water waves. The generator power take-off(PTO) system is modeled as a combination of a linear viscous damping and a linear spring. Using the frequency domain method, the optimal damping coefficient of the generator PTO system is derived to achieve the optimal conversion efficiency(capture width ratio).Based on the potential flow theory and the higher-order boundary element method(HOBEM), we constructed a threedimensional model of double-float WEC to study its hydrodynamic performance and response in the time domain. Only the heave motion of the two-body system is considered and a virtual function is introduced to decouple the motions of the floats. The energy conversion character of the double-float WEC is also evaluated. The investigation is carried out over a wide range of incident wave frequency. By analyzing the effects of the incident wave frequency, we derive the PTO's damping coefficient for the double-float WEC's capture width ratio and the relationships between the capture width ratio and the natural frequencies of the lower and upper floats. In addition, it is capable to modify the natural frequencies of the two floats by changing the stiffness coefficients of the PTO and mooring systems. We found that the natural frequencies of the device can directly influence the peak frequency of the capture width, which may provide an important reference for the design of WECs.

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.