Combined Wind-Storage Frequency Modulation Control Strategy Based on Fuzzy Prediction and Dynamic Control

To ensure frequency stability in power systems with high wind penetration,the doubly-fed induction generator(DFIG)is often used with the frequency fast response control(FFRC)to participate in frequency response.However,a certain output power suppression amount(OPSA)is generated during frequency support,resulting in the frequency modulation(FM)capability of DFIG not being fully utilised,and the system’s unbalanced power will be increased during speed recovery,resulting in a second frequency drop(SFD)in the system.Firstly,the frequency response characteristics of the power system with DFIG containing FFRC are analysed.Then,based on the analysis of the generation mechanism of OPSA and SFD,a combined wind-storage FM control strategy is proposed to improve the system’s frequency response characteristics.This strategy reduces the effect of OPSA and improves the FM capability of DFIG by designing the fuzzy logic of the coefficients of FFRC according to the system frequency index in the frequency support stage.During the speed recovery stage,the energy storage(ES)active power reference value is calculated according to the change of DFIG rotor speed,and the ES output power is dynamically adjusted to reduce the SFD.Finally,taking the IEEE 39-bus test system as an example,real-time digital simulation verification was conducted based on the RTLAB OP5707 simulation platform.The simulation results showthat theproposedmethodcan improve theFMcapabilityofDFIG,reduce the SFDunder thepremise of guaranteeing the rapid rotor speed recovery,and avoid the overshooting phenomenon so that the systemfrequency can be quickly restored to a stable state.

PERFORMANCE ANALYSIS OF ATM SWITCH FABRIC WITH COMBINED-INPUT/OUTPUT BUFFERING

This paper analyses the performance of the ATM switch fabric with Combined-Input/ Output Buffering(C-IOB) under two different service principles for the cells at the head of line (HOL) positions of input buffers: First Come First Service (FCFS)/Random Service(RS) for the set of HOL cells addressed to a given output port with different/same "age" (the waiting time at the HOL position) and Pure Random Service(PRS) for all HOL cells addressed to a given output port regardless of their "ages" while the Queue Loss (QL) transfer scheme is adopted for interaction between input and output buffers in the ATM switch fabric. The results obtained show that the C-IOB ATM switch fabric with PRS service policy and the QL transfer scheme is better than other buffering ATM switch fabrics.

CFD studies on the separation performance of a new combined gas–solid separator used in TMSR-SF

In order to comply with discharge standards, a gas–solid separator is used to remove solid particles from the thorium molten salt reactor-solid fuel (TMSR-SF) system. As a key component, it directly determines system energy efficiency. However, current gas–solid separators, based on activated carbon adsorption technology, result in high pressure drops and increased maintenance costs. In the present study, a new combined gas–solid separator was developed for the TMSR-SF. Based on a simplified computational fluid dynamics (CFD) model, the gas–solid twophase flow and the motion trajectory of solid particles were simulated for this new separator using commercial ANSYS 16.0 software. The flow and separation mechanism for this structure were also been discussed in terms of their velocity effects and pressure field distributions, and then the structure was optimized based on the influence of key structural parameters on pressure and separation efficiency. The results showed that the standard k–ε model could be achieved and accurately simulated the new combined separator. In this new combined gas–solid separator, coarse particles are separated in the first stage using rotating centrifugal motion, and then fine particles are filtered in the second stage, giving a separation efficiency of up to 96.11%. The optimum blade inclination angle and numbers were calculated to be 45° and four, respectively. It implicated that the combined separator could be of great significance in a wide variety of applications.

Improved Design of a 25 MW Gas Turbine Plant Using Combined Cycle Application

This paper presents the improved design of a 25 MW gas turbine power plant at Omoku in the Niger Delta area of Nigeria, using combined cycle application. It entails retrofitting a steam bottoming plant to the existing 25 MW gas turbine plant by incorporating a heat recovery steam generator. The focus is to improve performance as well as reduction in total emission to the environment. Direct data collection was performed from the HMI monitoring screen, log books and manufacturer’s manual. Employing the application of MATLAB, the thermodynamics equations were modeled and appropriate parameters of the various components of the steam turbine power plant were determined. The results show that the combined cycle system had a total power output of 37.9 MW, made up of 25.0 MW from the gas turbine power plant and 12.9 MW (an increase of about 51%) from the steam turbine plant, having an HRSG, condenser and feed pump capacities of 42.46 MW, 29.61 MW and 1.76 MW respectively. The condenser cooling water parameters include a mass flow of 1180.42 kg/s, inlet and outlet temperatures of 29.8°C and 35.8°C respectively. The cycle efficiency of the dry mode gas turbine was 26.6% whereas, after modification, the combined cycle power plant overall efficiency is 48.8% (about 84% increases). Hence, SIEMENS steam turbine product of MODEL: SST-150 was recommended as the steam bottoming plant. Also the work reveals that a heat flow of about 42.46 MW which was otherwise being wasted in the exhaust gas of the 25 MW gas turbine power plant could be converted to 12.9 MW of electric power, thus reducing the total emission to the environment.

Assessment of Site Parameters and Heat Recovery Characteristics on Combined Cycle Performance in an Equatorial Environment

This paper investigates the effects of site based parameters such as ambient temperature, humidity, altitude and heat transfer characteristic of a dual pressure heat recovery system on the performance of the combined cycle power plant within an equatorial environment. The bulk heat utilization and configuration of a dual pressure heat recovery system are investigated. It is observed that the heat system configuration play a vital role in optimizing the combined cycle overall performance, which has proportionality relationship with the operating ambient temperature and relative humidity of the gas turbine. The investigation is carried out within the ambient temperature range of 24℃ to 35℃, relative humidity of 60% to 80%, and a high level steam pressure of 60 bar to 110 bar. The results show that at 24℃ ambient temperature, the heat recovery system has the highest duty of 239.4 MW, the optimum combined cycle power output of 205.52 MW, and overall efficiency of 47.46%. It further indicates that as the ambient temperature increases at an average exhaust gas temperature of 530℃ and mass flow of 470 kg/s, the combined cycle power output and efficiency decrease by 15.5% and 13.7% respectively under the various considerations. This results from a drop in the air and exhaust mass flow as the values of the site parameters increase. The overall results indicate that decreasing the ambient temperature at optimum exhaust gas flow and temperature increases the heat recovery system heat duty performance, the steam generation, overall combined cycle power output and efficiency, which satisfies the research objective.

Temperature distribution of fluids in a two-section two-phase closed thermosyphon wellbore

Compared with a conventional single section two-phase closed thermosyphon （TPCT） wellbore, a two-section TPCT wellbore has better heat transfer performance, which may improve the temperature distribution of fluid in wellbores, increase the temperature of fluid in wellheads and even more effectively reduce the failure rate of conventional TPCT wellbores. Heat transfer performance of two-section TPCT wellbores is affected by working medium, combination mode and oil flow rate. Different working media are introduced into the upper and lower TPCTs, which may achieve a better match between the working medium and the temperature field in the wellbores. Interdependence exists between the combination mode and the flow rate of the oil, which affects the heat transfer performance of a two-section TPCT wellbore. The experimental results show that a two-section TPCT wellbore, with equal upper and lower TPCTs respectively filled with Freon and methanol, has the best heat transfer performance when the oil flow rate is 200 L/h.

Quadratic Stabilization of Switched Uncertain Linear Systems: A Convex Combination Approach

We consider quadratic stabilization for a class of switched systems which are composed of a finite set of continuoustime linear subsystems with norm bounded uncertainties. Under the assumption that there is no single quadratically stable subsystem, if a convex combination of subsystems is quadratically stable, then we propose a state-dependent switching law, based on the convex combination of subsystems, such that the entire switched linear system is quadratically stable. When the state information is not available, we extend the discussion to designing an outputdependent switching law by constructing a robust Luenberger observer for each subsystem.

计及氢能高效利用和热电灵活输出的综合能源系统源荷灵活运行策略

为进一步发挥氢能高效利用优势,构建绿色低碳能源系统,提出一种计及氢能高效利用和热电联产灵活输出的综合能源系统源荷灵活运行策略。首先,对源侧供能模型进行两方面改进:一是引入含风电制氢、燃气混氢、多能用氢和储氢的氢能利用模型,并考虑到电解水和甲烷化反应过程中的热量散失情况,引入热量回收装置,构建计及热量回收的氢能高效利用模型;二是针对常规热电联产灵活性不足的问题,构建含电锅炉和有机朗肯循环的热电灵活输出模型,以解耦常规热电联产“以热定电”和“以电定热”限制。其次,在荷侧引入含可转移、可削减和可平移的电、热柔性负荷,以缓解电、热负荷峰谷差,并与源侧相结合,形成源荷灵活运行模型。最后,综合考虑阶梯型碳交易成本、设备运行维护成本、弃风成本以及购能成本,建立综合能源系统源荷灵活优化运行模型。采用CPLEX求解器对所提综合能源系统源荷灵活运行模型进行求解,并设置不同场景进行对比。结果表明,相比常规氢能利用模型,考虑所提计及热量回收的氢能高效利用模型时,系统的总成本、碳排放量分别降低了1.92%、4.22%,并且引入热电联产改进模型后,其总成本、碳排放量可进一步降低4.08%、7.32%,实现系统低碳、经济和灵活运行。

建设海洋强国背景下船舶与海洋工程专业实践教学系统

为培养本科生的工程实践创新能力,开展了船舶与海洋工程专业实践类课程体系建设,建设具有“虚实结合、科教融合、开发海油”特色的实践教学资源库,搭建了“双创—竞赛—实习—设计”递进式实践创新培养平台。基于该平台,学生通过参加各级学科竞赛和创新实践活动,激发内驱力、聚焦任务、主动探索,实现了学习产出。这些举措有效提升了学生的实践创新能力,实现了“智能+教学”向“智能+发展”的转化。

计及改进阶梯型碳交易和热电联产机组灵活输出的园区综合能源系统低碳调度

为了进一步降低园区综合能源系统(park-level integrated energy system,PIES)碳排放量,优化热电联产(combined heat and power,CHP)机组出力的灵活性,提出一种考虑改进阶梯型碳交易和CHP热电灵活输出的PIES低碳经济调度策略。首先,将遗传算法与模糊控制相结合,设计一种遗传模糊碳交易参数优化器,从而对现有阶梯型碳交易机制进行改进,实现该机制参数的自适应变化;其次,在传统CHP中加入卡琳娜(Kalina)循环与电锅炉(electricboiler,EB),构造CHP热电灵活输出模型,以同时满足电、热负荷的不同需求;然后,提出一种柔性指标——电、热输出占比率,进而计算出电、热输出占比率区间,以衡量CHP运行灵活性;最后,将改进阶梯型碳交易机制和CHP热电灵活输出模型协同优化,以系统运行成本和碳交易成本之和最小为目标,构建PIES低碳经济优化模型。算例分析表明,所提策略可有效降低经济成本和碳排放量,同时还可扩展CHP灵活输出调节范围,能够为PIES低碳经济调度提供参考。

基于光谱合束的双波长输出Nd:YAG固体激光器

报道了一种基于光谱合束的Nd:YAG固体激光器双波长光源。系统由两个固体Nd:YAG脉冲激光器通过光谱合束组合而成,两个固体Nd:YAG脉冲激光器可独立工作,有利于输出脉冲的波长调谐、功率调节和相对延迟调整。通过光栅的色散特性以及输出镜的共同外腔反馈将各个激光器锁定在不同波长,从而实现合束,获得的激光源中心波长锁定在1 061.5 nm和1 064.6 nm,两谱线中心间距为3.1 nm,组合光束的输出能量为173 mJ,组合光束的光束质量因子M2为2.8×2.2;两个Nd:YAG激光器独立工作的输出能量分别为94 mJ和92 mJ,在合束方向上的光束质量因子M2分别为2.7和2.1,在非合束方向上的光束质量因子M2分别为2.2和1.9;组合光束的输出能量为两个Nd:YAG激光器能量总和的93%,组合光束的光束质量因子与单个Nd:YAG激光束的光束质量因子M2基本相同。该双波长激光源满足波长间隔小、输出功率大小相近、同光轴等要求,在太赫兹波产生、测速激光雷达以及医疗仪器等应用领域具有重要作用。

灌溉与有机肥处理对冬小麦水分利用效率的影响

探究不同灌溉量和有机无机肥配施的组合处理对冬小麦生长及水分利用效率的影响,为冬小麦的科学施肥管理提供参考。以关中地区冬小麦‘小偃22’为研究对象,通过田间试验,采用等氮原则对有机肥与无机肥进行不同比例配施(F1,100%无机肥;F2,24%有机肥+76%无机肥;F3,48%有机肥+52%无机肥),结合2个水平的灌溉(充分灌溉W1和亏缺灌溉W2),共设计6个灌溉施肥组合处理(W1F1、W1F2、W1F3、W2F1、W2F2和W2F3)。通过测定冬小麦的生长指标(植株株高和叶面积指数)、0~200 cm土层土壤体积含水率(以20 cm为深度间隔)和小麦的产量及构成要素(干物质量、穗长、有效穗数、千粒质量和籽粒产量),分析灌水量与有机无机肥配施对冬小麦生长及水分利用效率(WUE)的影响。结果表明:(1)充分灌溉(W1)条件下,F2、F3处理株高较F1处理分别提高3.4%~21.2%和0.8%~15.9%,叶面积指数提高5.7%~18.5%和16.8%~47.4%,干物质量提高12.1%~26.1%和21.1%~36.0%,穗长提高12.5%和14.5%,有效穗数提高6.6%和9.3%,千粒质量提高18.3%和24.4%,籽粒产量提高14.8%和28.6%,WUE提高14.6%和27.5%;亏缺灌溉(W2)条件下,与F1处理相比,F2、F3处理株高分别提高8.5%~16.2%和0.5%~10.6%,叶面积指数提高4.9%~20.7%和17.0%~50.0%,干物质量提高7.7%~25.7%和15.0%~34.6%,穗长提高12.3%和18.5%,有效穗数提高7.4%和18.0%,千粒质量提高15.3%和25.1%,籽粒产量提高13.1%和31.8%,WUE提高21.4%和35.2%。在相同灌溉水平下,有机无机肥配施处理可以提高土壤体积含水率。(2)W2F2处理对冬小麦株高增长最有效,灌浆期达最大值,较W1F1处理增长10.4%;W2F3处理对冬小麦叶面积指数、干物质量、穗长、有效穗数、千粒质量影响最大,成熟期较W1F1处理分别提高23.6%、39.0%、20.3%、18.4%和33.1%。(3)W2F3处理对冬小麦籽粒产量和WUE的影响最为显著,W1F1、W1F2、W1F3、W2F1和W2F2处理籽粒产量分别提高了35.5%、18.0%、5.3%、31.8%和16.6%;W1F1、W1F2、W1F3、W2F1和W2F2处理WUE分别提高了52.6%、33.2%、19.7%、35.2%和21.4%。亏缺灌溉与48%有机肥+52%无机肥组合处理的冬小麦籽粒产量和WUE最高,该灌溉施肥管理方案为关中平原及环境相似地区冬小麦的科学施肥管理提供了科学依据。

计及组合区间不确定性分析的光伏出力动静态赋权搜索预测模型

针对目前光伏出力确定性预测缺乏考虑不确定性信息导致预测精度受限的问题,提出了一种计及组合区间不确定性分析的光伏出力动静态赋权搜索预测模型。首先分别构建卷积神经网络(convolutional neural network,CNN)-注意力机制(attention)-双向长短期记忆网络(bidirectional long-short term memory,BiLSTM)(CNN-Attention-BiLSTM)和自然梯度提升(natural gradient boosting,NGBoost)模型进行确定性预测;然后通过分析2个模型的确定性预测值和真实值的分布揭示了组合区间相对可靠性规律,基于该规律提出一种动静态赋权搜索预测模型,利用NGBoost模型进行不确定性预测,并根据所提供的概率分布信息,动态区分确定性预测结果的重要性,结合模型历史静态的指标评价信息,实现组合区间内搜索预测结果;最后采用澳大利亚沙漠知识太阳能中心和宁夏某光伏电站的数据集进行仿真研究,验证了该文方法的有效性和适用性,可为光伏出力确定性组合预测提供新的研究思路。

回收船舶柴油机余热的双回路有机朗肯循环系统性能分析

为了降低船舶二氧化碳排放,利用双回路有机朗肯循环(DORC)系统对船舶柴油机的排烟和缸套冷却水余热进行回收发电。通过夹点温差法构建热力学模型,高温回路用于回收排烟热量,低温回路用于回收缸套冷却水热量和高温回路冷凝热。分析9对工质组合时DORC系统的冷凝器热力学参数对系统性能的影响,结果表明:随着高温回路的冷凝温度和冷凝热负荷的增高,低温回路蒸发压力和净输出功呈现升高趋势,在高温回路冷凝热负荷为715.2 kW~1 241.2 kW时,系统总净输出功呈现先升高后降低的趋势。当高温回路采用环乙烷,低温回路采用一氯三氟丙烯(反式)为工质时,系统总净输出功可达到410.6 kW。

联合循环发电站电力输出预测

为了使联合循环发电站利润最大化,准确预测其满负载电力输出非常重要。联合循环发电站运行时,前一级产生的废气被用来驱动下一级热机,以此来推动发电机,其满负载电力输出受到环境温度、大气压强、相对湿度和废气气压的影响。为此,首先,采用核主成分分析(kernel principle component analysis,KPCA)对电站发电相关的特征进行特征组合降维完成特征提取;然后,采用极端梯度提升(extreme gradient boosting,XGBoost)算法进行特征重要性评分,并结合序列前向选择法(forward selection,FS)获取最优特征子集;最后,构建了KPCA-XGB-FS模型用于联合循环发电站满负载下小时电力输出预测。通过对某联合发电站的真实数据进行实验,并与使用相同数据的已有研究方法进行对比,结果表明,所提出方法能够有效对电力输出进行预测,预测结果优于已有的研究方法。

基于EEMD-SVR模型的光伏功率预测

受天气因素的影响,光伏出力具有较强的不确定性和波动性,导致光伏功率的预测难度较大。针对光伏功率的预测问题,提出一种集合经验模态分解(EEMD)和支持向量回归(SVR)模型的预测方法。首先,对光伏功率进行集合经验模态分解,将光伏功率信号分解为多个特征模态分量以及一个残余分量;其次,使用SVR模型训练数据,实现分量预测;最后,结合预测分量预测光伏功率。结果表明,该模型可以实现对非平稳序列的可靠分解,并能有效提高光伏预测的平均绝对百分比误差(MAPE)性能。

基于灰色变权组合模型的河南粮食产量预测分析

科学合理地考虑各生产资源要素在农业中的运用,促进粮食产量的稳定增长,是保障粮食安全的关键。选取河南省2005~2021年粮食产量及相关因素数据,利用灰色关联模型提取影响粮食产量的主要影响因素,基于方差倒数加权法构建由GM(1, N)、Lasso回归、BP神经网络组成的多变量变权重组合预测模型,对河南粮食产量的变化趋势进行拟合与预测。结果表明,变权重组合预测模型的预测误差为0.589%,预测精度高且性能稳定;预测河南粮食产量在2022~2025年将会保持稳定增长,并在2025年达到73 282.65 kt。

相关性分析在水泥粉磨系统调试中的应用

湖南某水泥厂~#1生产线采用160-140辊压机+V选+Φ4.2 m×12.5 m球磨机+高效选粉机的闭路联合粉磨系统,台时产量180 t/h,工序电耗约33 kWh/t,成品比表面积337 m~2/kg。技改后出现质量波动,针对问题采用相关系数方法分析原因,提出对策,最终将系统台时产量稳定于210 t/h、工序电耗27.8 kWh/t、成品比表面积368 m~2/kg,系统生产全面满足考核指标。

基于组合模型的农村环境污染治理成本预测研究

针对环境治理过程中存在的资金浪费、成本缺乏合理规划等问题,提出基于组合模型的农村环境污染治理成本预测研究。从资源使用、环境破坏、环境治理三方面确立成本核算体系,优化成本函数;利用前窥式神经网络设定不同训练规则,分析污染治理过程中投入与产出的关系;使用大量随时间变化的数据建立差分自回归平均模型,结合过去值与过去误差,获得变量未来值;设计小波神经网络学习过程,引入尺度与平移因子,计算每个连接层权重,经过反复学习,确保预测误差最小;整合两个模型预测结果,运算单一模型权重,输出最终成本预测值。在实际区域的实验表明,所提组合模型不仅能够准确预测单项指标的治理成本,还能从长期角度出发,提高整体成本预测精度。

湿冷机组热电联产低品位热能供热热经济性分析

针对机组使用中排抽汽供热时,存在(火用)损较大的问题,提出了低品位热能供热的供热改造方案。低品位热能供热技术实现了用乏汽去进行热网一次换热,对进入高温热源加热器的热网回水进行预热,降低热网二次换热的温差。与传统的中排抽汽供热模式进行比较,改造后,供热汽源由中压缸排汽改为乏汽,降低了平均热源供热温度,大幅降低了供热热源在热网中进行换热时的温差,换热前后热源蒸汽的平均(火用)损大幅降低,有效降低了煤耗,同时改善了全厂的平均供热能力和发电能力,机组改造热经济性良好,节能效果显著。