A case study investigation into the risk of fatigue in synchronous flywheel energy stores and ramifications for the design of inertia replacement systems
A case study investigation into the risk of fatigue in synchronous flywheel energy stores and ramifications for the design of inertia replacement systems
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DOI：
10.1016/j.est.2021.102651
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发表时间：
2021-07
影响因子：
9.4
通讯作者：
J. Rouse;S. Garvey;B. Cárdenas;A. Hoskin;L. Swinfen-Styles;W. Xu
中科院分区：
文献类型：
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作者：
J. Rouse;S. Garvey;B. Cárdenas;A. Hoskin;L. Swinfen-Styles;W. Xu
飞轮是一种有吸引力的能量存储解决方案，原因有很多；高周转效率、长循环寿命和高“爬坡”功率率都在文献中得到了注意。几位作者也提出了基于飞轮的新型混合储能系统，由于系统架构中电源的固有划分，该系统为飞轮提供了在相对较大的时间尺度和负载频率范围内传递/接收能量的能力。在毫秒到秒的时间尺度上调节电网的电力波动是一个日益严重的问题，几乎所有正在进行脱碳的电网都面临着这个问题。同步飞轮储能系统具有吸引人的能力，能够以廉价和非常稳健的方式用“真实”惯性取代“真实”（被动控制）惯性。电网规模的飞轮设计需要仔细考虑，至于静态储能应用（即不用于运输的应用），主要驱动因素是降低制造和材料成本。最重要的是材料的有效使用，即它有足够的应力，这样飞轮就不会过大（因此昂贵），同时防止在使用期间发生灾难性故障的可能性。由于转速波动，疲劳有可能成为严重的寿命限制机制，但文献中缺乏深入的分析。目前的工作旨在量化飞轮的疲劳严重程度，这些飞轮通过将疲劳设计方法（如雨流循环计数方法和Ince和Glinka的广义应变幅法用于疲劳提升）应用于表示网格频率波动的加载场景来重新建立网格惯性。重要的是，飞轮的尺寸是基于不同的极限应力标准，从而使不同设计之间的结构能力使用水平不同。对于本工作中考虑的实际设计周期（代表经历正常频率波动的大型电网），所有预计寿命都非常大，这表明疲劳不是限制因素，任何经过测试的设计方法都是可行的。然而，如果在简单的严格弹性变体上实施弹性-完美塑性（基于Tresca）设计标准，则可以实现能量密度和单位能量存储成本的显着改善。为了简化而忽略控制成本，可以实现能量密度≈74%和单位能量存储成本≈290%的改进。
Flywheels are an attractive energy storage solution for many reasons; high turnaround efficiencies, long cycling lives and high “ramp-up” power rates have all been noted in the literature. Novel flywheel based hybrid energy storage systems have also been suggested by several authors which, due to the inherent partitioning of power sources in the system architecture, provide capacity for flywheels to deliver/receive energy over a comparatively large range of time scales and loading frequencies. Accommodating grid power fluctuations at the millisecond to second time scale is an ever growing problem that almost all grids undergoing de-carbonisation are facing. Synchronous flywheel energy storage systems have the attractive capability of being able to replace “real”(passively controlled) inertia with “real” inertia in a cheap and very robust manner. Flywheel design at the grid scale warrants careful consideration, as for static energy storage applications (ie those not used in transportation) the main driving factor is the reduction of manufacturing and material costs. It is paramount that material is used effectively, ie it is sufficiently stressed such that the flywheel is not oversized (and therefore expensive) while simultaneously guarding against the likelihood of catastrophic failure during service. Fatigue has the potential to be a serious life limiting mechanism due to fluctuating rotational speeds, however in depth analysis is lacking in the literature. The present work looks to quantify the severity of fatigue in flywheels which re-establish grid inertia by applying fatigue design methods (such as the rainflow cycle counting method and the generalised strain amplitude methods of Ince and Glinka for fatigue lifing) to loading scenarios that represent grid frequency fluctuations. Importantly flywheels are sized based on different limit stress criteria, thereby enabling differing levels of structural capacity usage between designs. For the realistic design cycles considered in the present work (representative of a large scale grid undergoing normal frequency fluctuations) all projected lives are extremely large, suggesting that fatigue is not a limiting factor and that any of the tested design methodologies is viable. Significant improvements in energy density and cost per unit of energy stored may however be achieved if elastic–perfectly-plastic (Tresca based) design criteria are implemented over simple strictly elastic variants. Neglecting containment costs for simplicity, improvements in energy density of≈ 74% and cost per unit of energy stored of≈ 290% are demonstrated to be achievable.