几乎人人都知道数据中心，并意识到其在我们生活的现代互联世界中的重要性。然而，我们对这些信息库的依赖程度可能仍然会让IDC分析公司预测到2025年实现互联的60亿人中的大多数感到惊讶。IDC报告（"2025数据时代"）还预测，届时，这些互联的每个人每天都会通过家庭、办公室和基于云的设备与数据中心互动近5000次，这几乎是当前每日三倍的量。这种广泛的应用，加之部署的数十亿不断产生数据的物联网节点，意味着到2025年，社会每年预计将产生175ZB的数据 - 而且增长速度正在加快。

数据中心面临的挑战

Challenges for data centers

数据中心面临的最大挑战之一是如何应对飞速增长的数据量以及用户日益频繁的访问。物理空间总是很宝贵的，同时在许多情况下，获得必要的电力可能是一个挑战。事实上，许多数据中心位于电力基础设施冗余的重工业区域，只为继承宝贵的遗留电力供应合同。

对于大多数数据中心来说，运营支出（opex）往往非常重要，因此，为了保持竞争力，他们必须提高存储密度并降低运行成本。除了服务器和其他设备所需的电力外，用于冷却的空调（AC）是一项重要的运营支出，并且也是数据中心运营商集中精力节约成本的一个领域。方法之一是让设备在较高的温度下运行，从而减少空调需求，节省空间和能源。为了实现这一目标，安装在数据中心的设备必须能在这些高温下长期可靠地运行。

毫无疑问，数据中心的可靠性至关重要，无论是在数据完整性方面，还是在一年中每一天每天 24 小时保持数据正常访问的运行时间方面。然而，有许多潜在的情况会危及这一点，包括设备故障、停电、蓄意破坏和人为失误。

防范电源故障的核心在于UPS系统，它能够在紧急情况下为数据中心提供短时间供电。电池容量的配备需满足100%的正常运行时间，这意味着电池放电要弥补这个时间差，直到发动机达到正常速度并且负载可以转移到发电机组，直至电网电力源恢复。在过去，这个 "自主时间 "通常需要10-15分钟左右，但随着发电机越来越自动化或能够在一分钟内进行远程操作，典型的自主时间可以少于5分钟。这种时间减少意味着需要更少的电池，从而释放出的空间，可用于增加服务器和存储容量。

铅酸电池和薄板纯铅（TPPL）电池

Lead acid and TPPL batteries

几十年来，铅酸化学一直是储能的基本中坚力量，随着时间的推移，这项技术不断得以改进。传统的富液铅酸电池，存在过量的液体电解质，会在正极产生氧气，在负极产生氢气，随着时间推移会导致水分流失。因此，电解质必须定期添加水。这也意味着会产生相对高浓度的气体，需要通风。

（注：此类电池容量较大，在北美使用较广，在国内很少有应用）

阀控式铅酸电池（VRLA）开始取代早期的铅酸电池类型。在这里，电解液被固定在凝胶或吸收性玻璃垫（AGM）上，大大减少了运行过程中的电解液损耗，并消除了加液的需要。VRLA技术在运行中产生的气体也少得多，极大地降低了通风的需要，同时又节省了相关成本。

多年来，基于AGM的VRLA电池使用铅钙/铅钙锡的厚铸网格合金，一直是数据中心UPS安装中最常用的电池。然而，最近一种采用薄板纯铅（TPPL）的新型AGM VRLA电池使铅酸技术进一步向前发展。

在基于TPPL的AGM VRLA电池中，更薄的高纯度栅格被用来制造板块，从而增加了表面积，改善了栅格和活性材料之间的接触。由于这些电池板本身较薄，因此可以在电池内堆叠更多的电池板，从而提高TPPL电池的能量密度。进而，这意味着TPPL电池可以应对更大的峰值电流，以及能够更快地（重新）充电。

TPPL技术在数据中心应用中的优势

Benefits of TPPL technology in data center applications

TPPL电池比标准AGM VRLA电池有更长的寿命，能够提供大约8-10年的使用寿命，增加约25%。它们占用的空间也减少了约20%，从而为创收的服务器腾出了空间。更小的 TPPL 电池尺寸与现代模块化数据中心安装趋势高度兼容。

在较高工作温度下交流电减少，但是TPPL电池也很少受到影响，尽管工作温度能最大程度地降低拥有总成本，但是在实际计算成本时，将取决于单个数据中心的配置。

Is your UPS really up to the job?

Michael Sagar | September 27, 2021

Almost everyone is aware of data centers and realizes that they are important in the modern, connected world in which we live. However, the extent to which we rely on these information repositories will probably surprise the majority of the six billion individuals that analyst firm IDC predicts will be connected by 2025. IDC’s report (‘Data Age 2025’) goes on to forecast that each of these individuals will interact with a data center almost 5,000 times each and every day through home, office and cloud-based devices – almost three times the current daily rate. This widespread usage, along with the billions of deployed IoT nodes that generate data constantly mean that, by 2025, society is predicted to generate 175ZB of data each year – and the growth rate is accelerating.

One of the greatest challenges for data centers is simply coping with the spiraling amount of data and the increasingly frequent user accesses to that data. Physical space is always at a premium and in many cases obtaining the necessary electrical power can be a challenge. In fact, many data centers are sited on redundant heavy industry sites, simply to inherit the valuable legacy electricity supply contracts.

Operating expenditure (opex) is generally significant for most data centers so, to remain competitive, they have to increase storage density and reduce running costs. Other than the power needed for the servers and other equipment, air conditioning (AC) for cooling is a significant opex and an area where data center operators focus cost saving efforts. One approach to this involves allowing equipment to run at an elevated temperature, thereby reducing the AC requirement, saving space and energy. In order to achieve this, the equipment installed in the data center has to be capable of operating with long-term reliability at these elevated temperatures.

There can be no question that the reliability of data centers is of prime importance, both in terms of data integrity as well as maintaining uptime 24 hours per day, every day of the year, for data access. However, there are many potential scenarios that can jeopardize this including equipment failure, power failure, sabotage and human error.

At the heart of guarding against power failure is the UPS system that is capable of powering the data center for a short time in an emergency. The battery capacity is sized to ensure 100% uptime, meaning that it needs to bridge the gap until generators are brought up to speed and loads can be transferred to the genset until grid power is restored. In the past, this ‘autonomy period’ would have generally been around 10 – 15 minutes although, as generators are increasingly automated or able to be remotely operated in under a minute, the typical autonomy period can be less than 5 minutes. This time reduction means that fewer batteries are required, thereby freeing up space that can be used to increase server and storage capacity.

The lead-acid chemistry has been a fundamental stalwart of energy storage for many decades, and over time there have been enhancements made to this technology. Traditional flooded lead-acid batteries, where excess liquid electrolyte is present, generate oxygen at their positive electrodes and hydrogen likewise at their negative electrodes, thereby causing water loss over time. Consequently, the electrolyte must be topped up with addition of water on a regular basis. It also means that relatively high levels of gas are generated, which require ventilation.

Valve regulated lead-acid (VRLA) batteries began to supersede the earlier lead-acid types. Here, the electrolyte is immobilized with either a gel or an absorbent glass mat (AGM) that significantly reduces electrolyte loss during operation and removes the need for topping up. VRLA technology also produces much less gas during operation, dramatically reducing the need and associated costs for ventilation.

AGM-based VRLA batteries that use a thick cast grid alloy of lead calcium / lead calcium tin have been the most commonly used batteries in data center UPS installations for several years. However, recently a new type of AGM VRLA battery that employs thin plate pure lead (TPPL) has moved lead-acid technology significantly further forward.

In TPPL based AGM VRLA batteries, thinner grids of very high purity are used to make the plates, resulting in an increase in the surface area which improves the contact between the grid and the active material. As these plates are inherently thinner, more of them can be stacked inside the battery, thereby increasing the energy density of TPPL batteries. In turn, this means that TPPL batteries can cope with larger peak currents as well as being able to (re)charge more quickly.

TPPL batteries have greater longevity than standard AGM VRLA batteries and are able to provide a service life of around 8-10 years, an increase of approximately 25%. They also occupy around 20% less space which frees up space for revenue generating servers. The smaller size of TPPL batteries is highly compatible with the modern trend of modularizing data center installations.

TPPL batteries are also less affected by the higher operating temperatures associated with reduced AC, although the calculation as to what operating temperature represents the greatest overall reduction in total cost of ownership includes several factors and will therefore depend on individual data center configurations.

The ability of TPPL batteries to recharge more quickly than other types means that they are better able to deal with multiple outages during a short period of time. Additionally, the low inherent self-discharge means that, once charged, TPPL batteries can be stored for up to two years without requiring any additional charging.

As data centers continue to increase in importance, so the need for UPS backup and advanced battery technology also increases. The industry has relied on various forms of lead-acid batteries for decades, evolving into the latest generation TPPL-based type. These offer a number of advantages including lower maintenance, higher operating temperature, faster recharge, greater charge retention and increased power density, all of which enhance the ease of integration and help reduce the total cost of ownership.

DeepKnowledge

翻译：

蒋毓蓉

DKV（Deep Knowledge Volunteer）普通成员

校对：

刘海峰

DKV（Deep Knowledge Volunteer）普通成员

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