Heat Transfer Analysis in Cooling System of Hydropower’s Generator

Cooling process of power plant generator is handled via air-cooled radiators in which the cooling water is supplied from lake with its water temperature varies from season to season. In this study, the effect of temperature fluctuations of cooling water entering the cooling system has been examined via analysis of energy (NTU method) and exergy. The exergy analysis has been done by definition of efficiency coefficient for exergy of cooling media (water) and heating media (air). Besides, the effect of changing the cooling water temperature and flow rate entering the radiators on the cooling system performance has been studied. The results revealed the generator cooling system performance level held sufficient till the temperature of inlet water was kept under 293 k (20°C). On one hand, when the temperature of cooling water at the inlet rises to 12°C, the rate of heat exchange at radiators falls up to 34.3%. On the other hand, by water temperature passing the 12°C limit, the efficiency of cooling media exergy falls to 78% leading to efficiency rise in radiators’ heating media exergy level to 61%. According to the results of this study, changing flow rate of cooling media up to 40% gives rise to the efficiency coefficient of radiators’ cooling media exergy level to about 18.7%. While it does not affect the efficiency level of energy at radiators, the flow rate rise of cooling media may not be considered as a way to give rise to efficiency level of radiators.

Integrated Power Generation Scheduling Compilation Method for Large-scale Small Hydropower Station Group

针对小水电无序管理，弃水、窝电现象严重，水资源浪费问题突出的现状，设计省地一体化小水电发电计划编制方法。该方法规范了小水电计划编制流程，对发电计划实行分级制作与管理，增加了输电断面安全校核环节，并给出了超限断面计划调整方法，通过建议计划上报一输电断面校核一计划协调发布的闭环方式有效提高了发电计划的准确性和可操作性。该方法目前已应用于云南电网小水电管理系统，方法的科学性与有效性得到了实际工程的验证。

Impact of climate change on hydropower generation in Rio Jubones Basin, Ecuador

This study attempted to use the soil and water assessment tool(SWAT), integrated with geographic information systems(GIS), for assessment of climate change impacts on hydropower generation. This methodology of climate change impact modeling was developed and demonstrated through application to a hydropower plant in the Rio Jubones Basin in Ecuador. ArcSWAT 2012 was used to develop a model for simulating the river flow. The model parameters were calibrated and validated on a monthly scale with respect to the hydro-meteorological inputs observed from 1985 to 1991 and from 1992 to 1998, respectively. Statistical analyses produced Nash-Sutcliffe efficiencies(NSEs) of 0.66 and 0.61 for model calibration and validation, respectively, which were considered acceptable. Numerical simulation with the model indicated that climate change could alter the seasonal flow regime of the basin, and the hydropower potential could change due to the changing climate in the future.Scenario analysis indicates that, though the hydropower generation will increase in the wet season, the plant will face a significant power shortage during the dry season, up to 13.14% from the reference scenario, as a consequence of a 17% reduction of streamflow under an assumption of a 2.9℃ increase in temperature and a 15% decrease in rainfall. Overall, this study showed that hydrological processes are realistically modeled with SWAT and the model can be a useful tool for predicting the impact of climate change.

Nonlinear fast–slow dynamics of a coupled fractional order hydropower generation system

Internal effects of the dynamic behaviors and nonlinear characteristics of a coupled fractional order hydropower generation system(HGS) are analyzed. A mathematical model of hydro-turbine governing system(HTGS) with rigid water hammer and hydro-turbine generator unit(HTGU) with fractional order damping forces are proposed. Based on Lagrange equations, a coupled fractional order HGS is established. Considering the dynamic transfer coefficient eis variational during the operation, introduced e as a periodic excitation into the HGS. The internal relationship of the dynamic behaviors between HTGS and HTGU is analyzed under different parameter values and fractional order. The results show obvious fast–slow dynamic behaviors in the HGS, causing corresponding vibration of the system, and some remarkable evolution phenomena take place with the changing of the periodic excitation parameter values.

Short-term power generation scheduling rules for cascade hydropower stations based on hybrid algorithm

Power generation dispatching is a large complex system problem with multi-dimensional and nonlinear characteristics. A mathematical model was established based on the principle of reservoir operation. A large quantity of optimal scheduling processes were obtained by calculating the daily runoff process within three typical years, and a large number of simulated daily runoff processes were obtained using the progressive optimality algorithm （POA） in combination with the genetic algorithm （GA）. After analyzing the optimal scheduling processes, the corresponding scheduling rules were determined, and the practical formulas were obtained. These rules can make full use of the rolling runoff forecast and carry out the rolling scheduling. Compared with the optimized results, the maximum relative difference of the annual power generation obtained by the scheduling rules is no more than 1%. The effectiveness and practical applicability of the scheduling rules are demonstrated by a case study. This study provides a new perspective for formulating the rules of power generation dispatching.

Dynamics in large generators due to oval rotor and triangular stator shape

Earlier measurements in large synchronous generators indicate the existence of complex whirling motion, and also deviations of shape in both the rotor and the stator. These non-symmetric geometries produce an attraction force between the rotor and the stator,called unbalanced magnetic pull（UMP）.The target of this paper is to analyse responses due to certain deviations of shape in the rotor and the stator.In particular,the perturbation on the rotor is considered to be of oval character,and the perturbations of the stator are considered triangular.By numerical and analytical methods it is concluded for which generator parameters harmful conditions,such as complicated whirling motion and high amplitudes,will occur.During maintenance of hydro power generators the shapes of the rotor and stator are frequently measured.The results from this paper can be used to evaluate such measurements and to explain the existence of complex whirling motion.

ABSTRACTSR-esearch on vibration protection strategy of large rotating machinery at hydropower station

The vibration protection strategy of large rotating machinery in thermal power and petroleum industry hasbeen applied for many years, but it still develops without breakthrough in hydropower unit operation due to thecomplication of its operation and vibration. According to this situation, the vibration protection strategy is proposedbased on the analysis of unit vibration mechanism. The vibration protection strategywith two functions of timelyprotection and fault diagnosis are of great engineering application value.

Run of River Bulk Hydroelectric Generation from the Congo River without a Conventional Dam

The paper discusses harvesting the Congo River for bulk hydroelectric generation based on run of river, low head generation technology, as employed at the existing Inga 2 power station in the Democratic Republic of Congo. The evolutionary approach builds on existing infrastructure.The results show that the footprint is much smaller than that which employs a conventional dam. The environmental impact is minimized. These collectively will contribute to lower capital costs. In summary, 10,000 cm3/sec of constant river flow will produce 5,000 MW of base power. On average, the constant recorded flow of the river is 30,000 cm3/sec and a total of 15,000 MW of base power generation is possible.

考虑水风光联合发电效益最大的水电站水库优化调度

为了经济合理地充分发挥水电站水库的调节能力,促进风光资源的高效消纳,基于微观经济学生产产品时存在的边际产量递减规律,以水电站水库调节能力为可变要素,将风光资源消纳视为“固定要素”的充分发挥,建立了水风光联合发电效益最大模型,可求解得到促进风光资源经济消纳的水电站水库优化调度方案。算例分析结果表明:在入库流量、负荷需求以及水库运行状态等因素一定的条件下,模型可充分反映水电站水库参与风光出力调节时对风光资源的消纳和水风光联合发电效益的贡献,给出了不同情景下水电站水库参与风光出力调节的优化调度方案,对于在保障电力系统安全的前提下充分发挥水电站水库的调节能力和提升水风光联合发电效益具有一定的参考价值。

考虑发电与弃水风险的梯级水电站水库风险调度模型

为量化梯级水电站水库调度过程中的风险形势,提出了预报信息驱动的梯级水电站水库风险调度模型。基于长短期记忆(LSTM)神经网络建立风险形势预测模型,通过构造预报入库径流、水库运行工况、调度决策与出力破坏程度和弃水量之间的映射关系,动态推演复杂工况下梯级水电站水库调度风险;建立基于风险形势的梯级水电站水库调度模型,提出发电不足风险预控模式和弃水风险预控模式。选取雅砻江流域下游锦屏一级和二滩水库组成的梯级水电站水库作为实例研究,结果表明:与常规发电量最大模型相比,风险调度模型通过提前降低出力来补偿未来出力破坏时段的发电量,锦屏一级和二滩水电站分别减小出力破坏程度46%、63%,通过提前增加发电流量预留库容来缓解蓄水期后续时段的弃水量,锦屏一级和二滩水电站分别降低弃水流量4.8%、5.4%;风险形势预测模型能够将径流不确定性嵌入风险调度模型中,通过风险预控决策动态响应水电站水库调度运行状态和径流形势变化,在保证梯级发电量的同时有效降低调度风险。

基于SSA-LSTM模型的水电站能效综合评价方法

随着我国电力体制改革不断深化,水电已告别传统粗放型发展模式,亟需配套更为成熟、通用的能效评价体系指导水电运行调度工作。因此,提出一种基于深度学习的水电站能效综合评价方法,引入长短期记忆网络(LSTM)构建水电站理论发电量模型,对于给定的原始发电序列,利用奇异谱分析(SSA)提取出其趋势项、周期项及噪声,对前二者分别构建LSTM网络模拟后叠加得到理论发电量计算结果,在此基础上提出相对增发效益指标、能效相对提高率指标,利用熵权法得到水电站综合得分值,进而对南部某省12座电站进行能效评价。结果表明,该方法可以充分反映水电在调度运行中的能效特点,研究结果对优化水电站调度策略、提高水电调度水平具有借鉴意义。

计及多时间尺度的梯级水-风-光互补基地储能容量优化配置

含高比例风光发电的清洁能源基地是碳中和的有效途径,但风光发电出力的随机性和波动性严重影响电网的安全稳定运行。为此,提出了一种计及水-风-光互补和电池分组运行的多时间尺度嵌套清洁能源基地储能容量优化配置方法。在含梯级水-风-光的清洁能源基地中加入电池组,并研究其三分组充放电控制运行策略。构建计及水-风-光互补的多时间尺度嵌套双层储能容量优化配置模型,其中内层利用水-风-光互补性,平抑大时间尺度的风光出力大波动,外层计及衰减度对储能进行优化,以平抑小时间尺度的风光出力小波动。通过算例分析表明所提模型能充分利用灵活调控的水电与快速响应电池的互补优势有效平抑清洁能源基地功率波动,并对比验证了所提三电池组分组控制策略在节约成本以及减缓损耗方面的有效性。

孤网模式下水轮机调速系统广义预测控制应用方法

针对孤网模式下水电机组PID控制策略鲁棒性差的缺点,提出基于双模型、实时反馈线性化、非线性特性补偿器和广义预测控制器的自适应广义预测控制策略(Adaptive Generalized Predictive Control,AGPC),以实现对水电站全工况实时最优控制。首先基于BP神经网络和改进樽海鞘算法构建高精度非线性水轮机模型,并结合PID控制器、引水系统、随动系统、发电机等模块搭建非线性水轮机调节系统仿真平台,然后通过定量计算揭示广义预测控制器直接应用于非线性水轮机调节系统的不合理性。进一步,结合实时反馈线性化和基于预估控制信号设计的水轮机非线性特性补偿器,提出孤网模式下广义预测控制器在水电站应用策略。最后,搭建了基于AGPC的非线性水轮机调节系统仿真平台,并以某电站真实数据验证了所提控制策略适用性、可靠性以及优良的鲁棒性。

基于改进NSGA-Ⅱ算法的梯级水电站多目标调度方法

近年来区域暴雨洪涝灾害的突发性、极端性、反常性显著增强,年内径流时空分布不均匀性进一步加剧,在梯级水电站汛期调度中均衡防洪与兴利任务成为重要研究课题。针对梯级水电站多目标联合调度问题,提出了一种基于NSGA-Ⅱ算法的求解方法,该方法改进了NSGA-Ⅱ算法的种群生成策略及精英选择策略,以梯级各电站时段平均防洪库容占用率作为防洪风险函数、梯级年发电量作为兴利目标函数,结合Pareto前沿分析方法求解了含防洪、兴利目标函数的梯级水电站联合调度问题。最后,以某流域梯级水电站多年平均来水条件下梯级联合调度为例对模型算法进行了验证分析。结果表明,基于改进NSGA-Ⅱ算法的梯级水电站多目标调度方法可以满足梯级水电站汛期防洪调度要求,同时梯级年发电量较常规调度图调度方式年发电量增加2.7%,更好地发挥了梯级水电站的综合效益。

气候变化下澜沧江流域径流及水电站发电能力预测

气候变化会对流域径流和梯级电站发电能力产生重要影响。基于历史和未来气候情景数据,综合利用WACM水文模型和梯级水电站发电模型,对澜沧江下游5个梯级水电站的出入库流量变化和发电能力进行预测。结果表明:①澜沧江流域未来气温会有一定程度上升,但GFDL-CM3、GISS-E2-R-CC和IPSL-CM5A-MR 3种气候模式下的降水变化趋势不一致,分别为增加8%~24%、减少15%~45%和变幅较小(-4%~7%);②上游来水在GFDL-CM3模式下明显增加(16.15%),在GISS-E2-R-CC模式下大幅减少(-30.67%),而在IPSL-CM5A-MR模式下变化不大(-2.01%);③梯级水电站年均发电量受上游来水的影响显著,保证出力对来水减少更为敏感,当年均流量下降30.67%时,保证出力下降约80%。研究成果可为澜沧江流域应对气候变化影响的水资源和梯级电站调度管理提供参考。

四川省燃气发电产业发展相关问题探讨

布局建设燃气发电机组,可提升电力安全稳定供应水平;燃气发电在顶峰时可发挥保供作用,在极端情况下可兜底保障。四川省燃气发电存在气源未得到保障、燃气机组调度运行有待优化、管网供气能力与气电项目用气需求不匹配、燃气发电价值与价格不一致、设备集中供应矛盾突出、接入系统设计不合理等问题。针对存在的问题提出了建立燃气机组发电用气保障机制、加快实施“两部制”电价、健全天然气市场体系、优化燃气机组调度运行、防范集中供货风险5项具体措施,可为四川省燃气发电健康发展提供有力保障。

兼顾生态的梯级水电站优化调度模型研究与应用

随着生态环境保护意识的提高,国家对水库开展生态调度的要求也不断提高。针对金沙江下游梯级电站复杂多样的生态调度需求,以经济效益最大为目标,建立针对产粘沉性卵鱼类生态调度和促进产漂流性卵鱼类繁殖生态调度的梯级水电站中长期优化调度模型;通过生态调度与电站运行目标的整体优化,得到生态调度开展时机的优化方案,实现兼顾生态调度和电站发电。在此基础上,选取丰、平、枯共30个典型年进行分析。结果表明:不同典型年下考虑生态调度后梯级发电量减少0.01%~0.27%,来水越丰,生态调度的影响越大。就整个消落期来看,生态调度与兴利调度没有明显的冲突,但会影响梯级电站的消落进度,导致上游两座电站消落提前1旬左右,对下游两座电站影响较小。

基于工况参数和改进LSTM的空冷器热风温度预测

针对传统抽水蓄能电站技术供水系统存在的智能化水平偏低,供水对象的温度与许多参数变量之间相互耦合的问题,建立了基于工况参数和改进长短期记忆(LSTM)神经网络的发电机空气冷却器热风温度预测模型.首先对原始数据进行清洗,其次采用随机森林(RF)特征降维,对参与目标预测的诸多高维测点变量进行重要度排序,验证所提的工况参数与预测对象温度的相关性,最后再将其输入PSO-LSTM神经网络进行模型的求解.将所提的基于工况参数和改进LSTM方法与最小二乘法、BP神经网络以及原始的LSTM方法进行对比.结果表明,所提模型能有效预测发电机空气冷却器热风温度,相较其他的模型,预测误差能够下降50%左右,同时拥有更优的预测稳定性.

农村偏远地区梯级小水电站长期优化调度策略

为解决偏远农村附近梯级小水电站面临的经济效益少、调峰能力差、发电稳定低等复杂问题,提出一种改进蜜獾算法(Improved Honey Badger Algorithm, IHBA),在考虑上述问题和保证传统水力约束的同时加入迎峰度夏顶峰和自供区供电等特殊发电约束,进行多目标优化调度。首先,通过Fuch混沌映射进行初始化,保证初始解均匀分布。其次,在更新阶段引入黄金正弦、哈里斯鹰围攻和T分布扰动混合策略,增强寻优能力,提高搜索解的质量。然后,结合非支配排序和理想点法,解决多目标问题。最后,将IHBA应用于湖南某农村地区梯级小水电站调度中与实际结果进行比较。结果表明:从年发电量、保证出力和发电保证率3项指标综合考虑,所提方法能有效提高发电综合效益,且在改善自供区供电能力及迎峰度夏顶峰能力同时以抬高水头的形式增加上级水库型电站高效发电,减少下级径流式电站低效发电。

未来不同情景下发电企业碳排放量预估

发电企业作为发电环节的主体具备高碳排放的特征,准确预估其在不同情景下的碳排放量有助于“双碳”目标的实现。目前碳排放量的预估聚焦于国家、部门、行业尺度,鲜少涉及企业尺度的研究。以湖北能源集团为例,基于皮尔逊相关性分析识别火力发电量的影响因素,通过神经网络、决策树、支持向量机(线性核函数、多项式核函数、径向基函数、Sigmoid核函数)、装袋算法、随机森林、线性回归、逐步回归算法分别构建火力发电量预测模型,并依据多种评价指标优选模型。随后以火力发电量和碳排放强度为边界条件,通过抽水蓄能发电、水电站低成本电解水制氢储能来削减企业的火力发电量,通过碳捕捉和碳封存技术来降低企业的碳排放强度。基于削减火力发电量和降低碳排放强度设定“结构减排方案”、“技术减排方案”、“综合减排方案”,推演各情景下的碳排放量。研究结果表明:利用线性回归、逐步回归模型预估火力发电量的效果良好;2030年“结构减排方案”“技术减排方案”“综合减排方案”下碳排放量分别为1648.89万~1934.07万t、1778.07万~1820.94万t、1345.75万~1571.77万t,2050年“结构减排方案”“技术减排方案”“综合减排方案”下碳排放量分别为0~1117.79万t、615.43万~649.70万t、0~299.20万t。本文提出的研究思路和方法可为企业尺度的碳排放量预估提供参考。