Pumped hydro energy storage and 100 % renewable electricity for East Asia

Rapid cost reductions have led to the widespread deployment of renewable technologies such as solar photovoltaics(PV)and wind globally.Additional storage is needed when the share of solar PV and wind in electricity production rises to 50–100%.Pumped hydro energy storage constitutes 97%of the global capacity of stored power and over 99%of stored energy and is the leading method of energy storage.Off-river pumped hydro energy storage options,strong interconnections over large areas,and demand management can support a highly renewable electricity system at a modest cost.East Asia has abundant wind,solar,and off-river pumped hydro energy resources.The identified pumped hydro energy storage potential is 100 times more than required to support 100%renewable energy in East Asia.

Present status of pumped hydro storage operations to mitigate renewable energy fluctuations in Japan

This paper focuses on pumped hydro energy storage(PHES)plants’current operations after electricity system reforms and variable renewable energy(VRE)installations in Japan.PHES plants have historically been developed to create electricity demand at night in order to operate base load power plants,such as nuclear power plants,in stable conditions.Therefore,many PHES plants are located midway between nuclear power plants and large demand areas.However,all nuclear power plants had to–at least temporarily–shut down after the Great East Japan Earthquake followed by a nuclear accident at Fukushima Daiichi in 2011,and renewable energy power plants have been deployed rapidly after the introduction of a feed-in-tariff(FIT)scheme.Therefore,PHES plants are being used to mitigate fluctuations of VRE,especially in areas where renewable energy has been significantly installed.The daily highest capacity ratio of PHES plants in Kyushu area has recorded three times higher than it in the other areas where the past operating mode is still conducted.But those operations on PHES plants are simply followed as a dispatch rule of the Organization for Crossregional Coordination of Transmission Operators(OCCTO),market-based operations have not been conducted enough yet.The market design shall be changed to harmonize VRE installation and PHES plants’operations are necessary to make the transition from the past operating mode of PHES plants across Japan.

Utilization of cross-regional interconnector and pumped hydro energy storage for further introduction of solar PV in Japan

The amount of solar PV installed capacity has steadily increased to 44.5 GW at the end of FY2017,since the introduction of the Feed in Tariff(FiT)to Japan in 2012.On the other hand,since the first curtailment of solar PV was conducted on October 13th,2018 in the Kyushu area,the curtailment has been frequently executed including wind power after that.In this study,cross-regional interconnector and pumped hydro energy storage(PHES)are focused on mitigating curtailment.In Japan,there are 9 electric power areas which connected each other by cross-regional interconnectors.According to the historical operation,cross-regional interconnectors were secured as emergency flexible measures,but after the implicit auction was started from October 2018,it is used on merit order.Regarding a PHES in Japan,they have been built with nuclear power plants for several decades.Because the output of nuclear power generation is constant,so the PHES is used to absorb the surplus at nighttime when the demand declines.All nuclear power plants in Japan have been shut down after the accident at the Fukushima Daiichi Nuclear Power Plant following the Great East Japan Earthquake that occurred on March 11th,2011.There are several nuclear power plants that have been restarted(9 reactors,as of August 2019).In this study,the amount of curtailment for solar PV in the Kyushu area is sent to the Chugoku area using the cross-regional interconnector(Kanmon line).Then,the PHES in the Chugoku area is pumping with low price.Because the spot price in the market is low when the curtailment is executed.After that,the PHES is generating at night with high price when the solar PV is not generating.It makes a profit by the deference for the cost of pumping and the revenue of generating by the PHES.As a calculation result,for one week from May 2nd to 8th,2019,a profit becomes 152.2 million JPY(about 1.22 million EUR).For this purpose,it is necessary to raise the operation capacity of the cross-regional interconnector up to the rated capacity with the frequency control function of solar PV instead of the capacity to keep frequency in the event of an accident.This will allow the further introduction of solar PV in Japan.

Enhanced Electric Power Adaptability Using Hybrid Pumped-Hydro Technology with Wind and Photovoltaic Integration

The integration of solar and wind energy into the electrical grid has received global research attention due to their unpredictable characteristics.Because wind energy varies across all timescales of utility activity,renewable energy generation should be supplemented and enhanced,from real-time,minute-to-minute variations to annual alterations influencing long-termstrategy.Wind energy generation does not only fluctuate but is also challenging to accurately forecast the timeframes of significance to electricity decision makers;day-ahead and long-term making plans of framework sufficiency such as meeting the network peak load annually.A utility that integrates wind and solar energy into its electricity mix would understand how to adapt to uncertainty and variability in operations while sustaining grid stability.Due to hydropower’s adaptability,a system using hydropower as one of its generating resources could be precisely adapted to absorb the variability of wind and solar energy.The objective of this research study is to create a hybrid system comprising hydro-wind and solar(Hybrid-HWS)integration for power balancing in an isolated electrical network in Klipkop village,Pretoria region,South Africa.The desirability of designing and building goaf storage tank in regard to capability,the fullness of line throughoutwater pumping,dispensing,storage tank spillage,and pressure difference throughout liquid flow within the storage tanks were preliminary assessed using geotechnical and weather forecasting data from a distinctive area of Klipkop town in Pretoria,South Africa.Different facility hours premised on daylight accessibility are scheduled to balance maximum load at early and late hours.However,in the scenario of electrical power,time shift requiring storage for extended periods of time,such as in terms of hours,Hybrid-HWS has been found to have a crucial role.The results of simulations showed a coordinated process design for Hybrid-HWS Energy Storage(ES)to determine everyday strategic planning in reducing the variability of the system resulting from wind-solar-pumped hydro ES output inadequacies and satisfy daily load demands.It could be recommended that by considering the adaptability characteristics,extremely rapidly,ramping,peaking support and maximum stabilizing aid of the system could be archived with pump-hydro into the energy mix which can provide specific guidelines for energy policymakers.

基于卧式抽蓄的风光水储蓄联合运行优化调度研究

随着大规模风电和光伏的接入,电力系统的稳定运行面临重大挑战。通过传统水电融合改造,构建卧式抽水蓄能电站,利用其快速启动和强大的调峰能力,可有效平抑风电和光伏的出力波动。提出了一种基于卧式抽蓄的风光水储蓄联合运行优化调度方法,通过可调水电与泵站的联合运行平抑风电和光伏出力波动,考虑系统的综合性能和改造可行性,建立了系统总输出与电力消耗负荷曲线之间差值平方和最小化的优化调度模型,采用POA优化方法对系统联合运行调度进行优化求解。结果表明,通过基于卧式风光水储联合运行优化调度,系统的平均日供电缺口显著减少,提高了能源利用效率,避免了资源浪费,增强了系统消纳清洁能源的能力。

全清洁能源下的高品质矿区能源系统配置优化方法

面向“30·60”双碳目标,矿区能源利用方式的绿色、经济、高效转型成为我国能源革命的迫切需求。西部矿区拥有丰富的可再生能源资源禀赋,但仍面临着可再生能源就地消纳困难,电力设备投资成本高、利用率低以及外送输电通道有限的困难。为提升矿区用能清洁化程度,提升矿区能源供给的稳定性与可靠性,增强矿区对外部电网的支撑能力,提出全清洁能源下的高品质矿区能源系统(High-quality Coal Mine Energy System,HCMES)及其配置优化方法。首先,考虑西部矿山综合能源系统的负荷特点与伴生能源利用,结合可再生能源发电与废弃矿井抽水蓄能,构建全清洁能源下的HCMES架构。其次,考虑到矿区生产全流程负荷的需求响应能力,考虑系统的能量平衡约束,提出全清洁能源下的高品质矿区能源系统优化配置模型。最后,以系统年平均综合成本最小化为目标,将原问题转化为混合整数线性规划模型,求解生成高品质矿区能源系统优化配置方案。以我国西部某年产煤量1200万t的矿区实际数据为实例,验证所提模型与方法的有效性,并分析可再生能源出力与生产负荷需求不确定性对系统优化配置结果的影响。算例仿真设置了4种矿区能源系统配置方式:不配置储能、配置抽水蓄能、配置电化学储能、配置抽水蓄能(不外购电能)。结果表明,所提出的HCMES相较于其他配置方式可减少电气一次设备投资11.11%,相较于方式3可降低年平均综合成本7.91%,且最多可减少矿区生产用能总二氧化碳排放量91.17%。

先进抽水压缩空气复合储能技术

储能技术的创新突破成为带动全球能源格局革命性、颠覆性调整的必经之路,是实现“碳中和、碳达峰”目标的重要举措。为此,西安交通大学“先进物理储能技术”研究团队创新性地发明了新型抽水压缩空气复合储能技术。该技术采用空气和水作为混合工作介质,利用水力机械设备和空气透平作为系统的复合做功设备,实现储能介质高效等温压缩/膨胀。相比于传统压缩空气储能技术,新型气液复合空气储能技术具有响应快、效率高、投资成本低等优点。团队通过10余年的攻关研究,完成了关键设备与储能系统的性能表征、时域特性研究、流体机械关键共性技术集中攻关、空气储能技术全寿命周期性能评估软件的研发及应用,研究成果可为气液复合压缩空气储能技术的规模化推广应用提供坚实的理论与数据支撑。

考虑梯级水电融合抽蓄改造的风光资源多目标容量配置

为实现梯级水风光蓄联合发电系统高效多能互补,研究考虑梯级水电融合抽蓄改造的风光发电多目标容量优化配置方法。以联合发电系统外送通道利用率最大和受端电网剩余负荷峰谷差最小为目标,优化联合发电系统风电和光伏发电的配置容量;考虑风电和光伏发电季节性波动,基于K-means聚类构建风电和光伏发电出力的典型场景,提出了梯级水风光蓄全场景互补运行模型,并发展了便于快速求解的混合整数线性化模型。以小金川梯级小水电周边的风电场与光伏电站为例,对所提方法的有效性进行了验证,分析了梯级水风光蓄联合系统的互补性,对比说明了混合式抽蓄在联合发电系统中的作用。

基于抽蓄协调的新能源纳入电力系统备用方法

大规模新能源并网后,传统的备用体系制约含高比例新能源电力系统的新能源消纳能力。为此,该文提出基于抽蓄协调的新能源纳入电力系统备用方法。首先,采用改进K-均值聚类算法生成各时段新能源出力预测典型场景;然后,基于广义新能源预测偏差及弃用风险约束,确定各时段各典型场景的最佳新能源纳入备用比例系数;最后,根据各时段的新能源预测数据和抽水蓄能机组的发电支撑状态,进一步调节所对应时段新能源纳入系统备用的最佳比例系数,将新能源合理地纳入系统备用。算例结果验证所提方法能够有效提升含高比例新能源电力系统新能源消纳能力,减少新能源弃用。

小水电改造混合式抽水蓄能机组对水光互补系统的发电影响研究

针对新型电力系统建设过程中,面临的小水电调节能力不足的问题,本文提出了梯级小水电与光伏互补运行的优化调度方法,实现了小水电改造混合式抽水蓄能机组对水光互补系统的影响评估,可指导水风光蓄多能互补运行。首先,以计算周期内系统发电量最大和系统总出力波动最小为目标函数,面向小水电的梯级水光蓄互补电站联合调度模型;其次,提出水光蓄互补电站联合调度模型求解的基本思路,并采用改进逐步优化算法进行模型求解计算;最后,依托四川省大渡河上游支流小金川流域开展实例研究,并通过梯级水光蓄互补调度结果与梯级水光互补调度结果的对比,分析抽水蓄能机组对水光互补系统的发电影响。研究结果表明:通过梯级水风光蓄互补调度和梯级水光互补调度计算,可实现抽水蓄能机组对水光互补系统发电影响的评估。本次研究成果对水风光蓄清洁能源基地规划建设和调度运行具有一定的思路借鉴和参考价值。

地下抽水蓄能发展综述

2060年碳中和场景下对储能需求量巨大,但是,我国常规抽水蓄能站点资源不足。针对这一问题,本文综述了美国、俄罗斯、新加坡、日本等国关于地下抽水蓄能的研究,提出基于硬岩掘进机挖掘的低成本地下抽水蓄能方案,阐述了三种不同地下抽水蓄能的发展现状,即人工挖掘地下空间的地下抽水蓄能,废弃矿井改造的地下抽水蓄能,以及其他地(海)下抽水蓄能。介绍了地下抽水蓄能的关键技术及其难点,包括地下工程建设与运营现状,以及高水头水泵水轮机技术的发展现状。最终,讨论了发展地下抽水蓄能的挑战,提出优先发展人工挖掘地下空间的地下抽水蓄能的建议,并对关键技术的发展方向提出建议。分析表明,地下抽水蓄能技术可行,经济可行,优势明显,建议我国加强对地下抽水蓄能技术的研发和推广应用。

面向海上风电高效利用的水下抽水蓄能容量优化配置分析

为应对以海上风电为代表的海洋新能源并网挑战,水下抽水蓄能(underwater pumped hydro storage,UPHS)受到日益广泛的关注。然而,现有UPHS研究聚焦点距能源电气领域较远,尚无对现实储能工程的容量配置和规划的深入分析。针对此问题,立足(准)稳态视角,围绕水下抽蓄的容量优化配置开展研究。首先,明确海上风电-UPHS系统结构,基于水下抽蓄原理与风电出力特性建立系统模型;之后,以最大化投资收益为目标,构建UPHS容量优化配置模型,求解目标算例风速条件下风电机组、水下储能的最佳容量与实时出力;最后,围绕UPHS关键参数对规划结果的影响开展对比分析。结果表明,水下储能的引入可以大幅提升远海风电场的建设规模与投资收益;同时建设尺寸、利用小时数等储能参数亦会对规划结果产生多角度影响。

“双碳”目标下云南省废弃矿山光伏-抽水蓄能发电站可行性分析

为助力“双碳”目标的实现以及对废弃、再生资源的循环利用,云南省利用矿山开采遗留下来的采空区建设清洁能源发电站符合现实需要。而在实际废弃矿山改造过程中,实现多元耦合开发利用模式,更有利于再生能源的渗透和维持电网的稳定运行。根据水光互补发电特性原理,结合云南省自然资源能源禀赋特征,从废弃矿山光伏-抽水蓄能电站工作原理及结构、关键技术、经济效益估算等几个方面论述云南省建设废弃矿山光伏-抽水蓄能发电站的可行性。分析结果表明,云南省已累计超过15亿m3的采空区及丰富的自然资源、能源为光伏-抽水蓄能电站建设提供了有利条件;且云南省近几年清洁电力的比重也在不断攀升,2022年,清洁电力的占比已达到87.7%;由废弃矿山光伏-抽水蓄能电站实例计算得出,该矿山每年可产生的电量收益达1.2亿元,按照设计年限20年计算,共计产出约24亿元的收益。综上所述,云南省废弃矿山光伏-抽水蓄能发电站建设优势较为显著。

不确定性条件下农业微电网与灌溉系统相结合的鲁棒优化调度

农业微电网以低成本的方式为偏远农村地区的能源供应提供了一种有前景的解决方案.综合考虑风光抽水蓄能一体化农业微电网满足用电负荷和用水负荷需求,在可再生能源出力及用电负荷需求的不确定性条件下,提出包含抽水蓄能(PHS)电站的孤岛型农业微电网和灌溉系统相结合的鲁棒优化调度模型,利用农村地区水资源富足的特点和风光抽蓄补偿的优势,在最小化系统总成本的同时提高可再生能源的消纳.所提模型考虑分布式发电、用电负荷和用水负荷需求、涡轮流量和灌溉流量,具有多样性、多约束、非连续的特点.提出一种引力鲸鱼优化算法(GWOA)求解该模型,在某农业微电网上的仿真结果表明,GWOA可以获得比CPLEX求解器及其他新开发算法更具竞争力的解.另外,探究了降水量不确定性引起灌溉系统用水负荷需求变化对系统运行成本的影响以及使用PHS电站的必要性.

黄河上游青海水风光蓄一体化发电系统研究

随着双碳目标加速落实与黄河流域生态保护和高质量发展规划实施,统筹推进水风光一体化基地建设并构建多能互补发电系统,能提升跨省跨区电网错峰支援和余缺互济能力。通过采用归纳梳理的方法对黄河上游青海省水风光资源和多能互补著绩进行了分析,结果表明:青海南部水电势能、北部太阳能和西部风能资源潜力较大,但各种新能源随开发规模的扩大其可开发潜力呈下降趋势。青海省规划的风光容量配比为0.6∶0.4,2025年情景下水电与风光配比为1∶1.2,2035年情景水平下为1∶1.25。此外,在电网系统中尽可能少接风电多接光伏且弃电率保证在5%以内对电网稳定运行和投资成本具有正反馈作用。

含混合式抽水蓄能电站的水光蓄日内互补运行研究

在传统水电机组基础上加入可逆式机组构成混合式抽水蓄能电站增加水电调节能力,可与光伏电站联合运行,平抑新能源发电的不稳定性。为研究不同季节典型日下,含混合式抽水蓄能电站的水光蓄互补运行方式,构建以发电量最大和出力波动最小为目标的水光蓄互补运行短期调度模型,提出双层嵌套模型求解思路,考虑光伏出力的波动性,求解不同运行工况下含混合式抽水蓄能电站的水光蓄互补运行短期调度模型。计算结果表明,在不同来水及不同光伏出力过程的前提下,混合式抽水蓄能电站可采取不同运行工况以满足目标函数,不仅可以促进光伏并网消纳,还可增加水电发电量,减少弃水,为大量光伏资源并网下混合式抽水蓄能电站运行方式提供参考。

光-蓄-储混合储能系统灵活性提升与容量规划

抽水蓄能电站是当前发展最为成熟、配置容量最大的储能设施,但其功率变化速率较慢,调节灵活性较为匮乏。电化学储能是当前发展最快的储能形式,具备灵活的功率调节能力。文中的目的在于构建光-蓄-储混合储能系统,通过不同储能设施的特性互补,大幅提升抽水蓄能电站的运行灵活性。文中基于抽水蓄能的功率振荡区间描述机组的功率调节能力,并根据单台机组的功率调节能力以及多台机组的组合方式定义抽水蓄能的灵活性。考虑灵活性约束以及提升机组运行寿命的需求,建立光-蓄-储混合储能系统的容量规划模型。以山东某抽水蓄能站为例,进行实例分析。结果表明,配置额定功率等于抽水蓄能容量10%的电化学储能系统可以提升40%的蓄-储系统灵活性,减少14%的机组发电启动次数。但在当前的两部制电价下,峰谷电价差需要超过0.5元/(kW·h)时电化学储能系统才具备盈利空间。

静止变频器损耗计算方法研究

静止变频器(Static Frequency Converter,SFC)是抽水蓄能机组变频启动的核心设备。为研究静止变频器在运行过程中损耗特性,分析了SFC主要功率部分包括晶闸管阀组和直流平波电抗器的损耗计算方法。利用开关器件和直流平波电抗器厂商提供的相关数据,对某抽水蓄能工程静止变频器损耗进行计算。结果表明损耗计算值与实测值相近,可为静止变频器冷却容量配置提供参考。

山阳抽水蓄能电站下水库坝址渗漏评价

水库渗漏问题既影响水资源的利用,又威胁水库的安全运行,是水库工程中的典型问题之一。为探究陕西山阳抽水蓄能电站下水库渗漏问题,以区域地质与水文地质条件为基础,结合地质钻探、压水试验等结果,分析了下水库的渗漏模式,得出下水库存在坝基渗漏和右坝肩绕坝渗漏问题,并通过解析法和数值法估算渗漏量,采用解析法估算出渗漏量为1054m^(3)/d,数值法得到的渗漏量为1783m3/d,得到渗漏量占总库容的0.020%~0.034%,小于总库容的0.05%,符合建库规范要求。

面向海上风电高效利用的水下抽水蓄能建模与控制

水下抽水蓄能(underwater pumped hydro storage,UPHS)是一种适应海洋环境的新型储能方法。针对此前UPHS模型较为粗略且适用范围窄的问题,构建了水下抽蓄的水力-机械-电气多环节暂态模型并开展相关研究。首先,分析推导UPHS各组成部分(水泵水轮机、调速器、电机、变流器)的物理模型;其次,分别设计了原动机和并网变流器的控制策略;最后,在单机并网和配合海上风电联合外送两种情形的多样化工况下对UPHS进行电磁暂态仿真,验证了模型的可靠性及其应用于海上风电外送功率平抑的有效性。