ANSI ATIS 0600015.12-2016 Energy Efficiency for Telecommunication Equipment Methodology for Measurement and Reporting Power Systems - Uninterruptible Power Supply Requirements.pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0600015.12.2016 Energy Efficiency for Telecommunication Equipment: Methodology for Measurement and Reporting Power Systems Uninterruptible Power Supply Requirements As a leading technology and solutions development organization, the Alliance fo

2、r Telecommunications Industry Solutions (ATIS) brings together the top global ICT companies to advance the industrys most pressing business priorities. ATIS nearly 200 member companies are currently working to address the All-IP transition, 5G, network functions virtualization, big data analytics, c

3、loud services, device solutions, emergency services, M2M, cyber security, network evolution, quality of service, billing support, operations, and much more. These priorities follow a fast-track development lifecycle from design and innovation through standards, specifications, requirements, business

4、 use cases, software toolkits, open source solutions, and interoperability testing. ATIS is accredited by the American National Standards Institute (ANSI). The organization is the North American Organizational Partner for the 3rd Generation Partnership Project (3GPP), a founding Partner of the oneM2

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10、essed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revis

11、e, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer however, it is also the least energy-efficient of the typical UPS operating modes. This mode

12、is sometimes called “Protected” or “Online”, and is referred to by standard IEC) definition as VFI. Dual-Corded End-use equipment with dual AC input power supplies, either of which can supply the entire equipment shelf. The purpose of the redundancy is for reliability, and this type of ICT equipment

13、 is commonly used in applications where maximum reliability (uptime) is desired/required. This is the equivalent of the telecommunications industrys A/B feeds for -48VDC-powered equipment. Line-Interactive A UPS operating mode where most of the power to the loads is provided by commercial AC; howeve

14、r any abnormalities in the sine wave are “fixed” by the addition of small amounts of power from the battery-fed inverter or via a self-adjusting transformer (which could be an autotransformer). This mode provides a compromise between the less-reliable Standby Mode, and the less energy efficient Doub

15、le-Conversion Mode. In other words, this mode has better energy efficiency than Double-Conversion Mode, but not as good as Standby Mode; and it provides more reliable power than Standby Mode, but not as reliable as that provided by Double-Conversion Mode. The IEC refers to this Line-Interactive oper

16、ating mode as VI. 1Available at: . 2Available at: . 3Available at: . 4Available at: . 5Available at: . 6Available at: . ATIS-0600015.xx.2009 3 Term Definition n+1 Internal redundancy (where loss of a single component doesnt jeopardize the common load) of inverters and/or rectifiers within a UPS. For

17、 example, a UPS system may be composed of 5 internal 25 kVA inverter modules, meaning that the total capacity of the system is 125 kVA, but the n+1 capacity of the system is 100 kVA. N+1 Multiple UPS power system sources are used to feed a maximum load of N, but loss of a single source leaves remain

18、ing sources capable of feeding the load. Standby Mode A UPS operating mode where the incoming AC power is routed directly to the equipment loads (with only a small portion being normally siphoned off to trickle charge the batteries through a rectifier). Backup is provided through a static transfer s

19、witch which quickly (typically within 1.2 to 4 ms) transfers the load(s) to the battery-fed inverter(s) when a commercial AC power problem is sensed. This mode of operating a UPS provides the least power protection (and thus the least reliability) to the load(s), but is the most energy-efficient mod

20、e of UPS operation. This mode is sometimes called Eco-mode because of its energy efficiency. It is also sometimes called “Off-line” mode. The standard IEC definition for this mode is called VFD. Tier rating system A rating system for critical power and HVAC systems defining the level of redundancy a

21、nd reliability on a scale from I to IV (1 to 4) with IV being the most redundant/reliable. Uninterruptible Power Supply An Uninterruptible Power Supply/System (UPS) provides power to AC loads, conditioned against commercial power faults by use of a rectifier, battery, and inverter systems, and possi

22、bly other power conditioning components. 3.2 Acronyms but the least reliable topology, as the protection for the loads from extreme over or under voltage or frequency events relies on a single-point-of-failure static transfer switch which typically takes 1.2-4 ms to transfer the loads to the battery

23、-fed inverter. This operating mode is represented by Figure 4.2 below. ATIS-0600015.xx.2009 6 Figure 4.2 VFD (Standby/Off-Line/Eco) Operating Mode An operating mode that provides some compromise between energy efficiency and output power reliability is known as Line-Interactive or Voltage Independen

24、t (VI). In this design or operating mode, most of the power is supplied from the commercial AC source, but often through either an isolating or auto-transformer, which can perform voltage adjustments, and/or the control electronics turn on the IGBTs of the inverter(s) periodically (when the need is

25、sensed) to provide some of the power to adjust for deviations in voltage or sine waveform. This topology is illustrated in Figure 4.3 below. ATIS-0600015.xx.2009 7 Figure 4.3 VI (Line-Interactive) Operating Mode Some medium-sized and larger UPS may be equipped with an input isolation transformer, wh

26、ich not only provides inductive protection from current waveform anomalies (which the transformer in some line-interactive UPS also provides), but keeps dangerous AC voltage (especially for larger 3-phase 480 VAC input UPS) off of the DC bus. However, use of this transformer has declined in newer UP

27、S due to user desires for lower-cost and higher-efficiency UPS, since any transformer causes efficiency losses. Finally, some newer UPS have a DC-DC converter between the DC bus and the batteries that gets rid of the low frequency (typically defined as below 667 Hz) AC ripple feedback from the inver

28、ter (with some small charger/rectifier contributions to that ripple) that is superimposed on the DC bus, and is so damaging to the batteries. This feature significantly lengthens battery life, but there is a very tiny efficiency loss associated with it. This topology is illustrated in Figure 4.4 bel

29、ow. Figure 4.4 DC-DC Converter in Series with the Batteries ATIS-0600015.xx.2009 8 Smaller size UPS (typically defined as those smaller than 10 kVA) typically consist of a single battery charger, a single string of batteries (typically configured in a nominal 24, 36, 48, 96, or 192 VDC ungrounded st

30、ring), and a single inverter, typically taking in and producing single-phase nominal 120 VAC power out in the North American market, although other AC voltages are available. Battery backup capacity can sometimes be extended through the addition of more battery strings, and possibly another charger.

31、 These smaller units are often sold with only a single-operating mode (either off-line or line-interactive) available, although other options (including dual conversion and user-settable modes) are also available in certain models. Medium sized UPS (typically ranging from 10-80 kVA) usually have a s

32、ingle battery charger, a floating DC bus operating typically between 192 and 405 VDC, one or more battery strings, and one or more inverters (the inverters may be in an internal n+1 configuration). In the North American Market, most of these medium UPS are three-phase and can have either a 480 VAC o

33、r 208 VAC input, 480 or 208 VAC for the output. If the desired output voltage differs from the input voltage, the output stage of UPS will have a transformer, which will also provide some protection for the load from current surges and poor current waveforms when a UPS is operating in the off-line/E

34、co or line-interactive modes. The largest UPS (typically larger than 80 kVA in size) have a battery charger and a DC bus operating between 400 and 768 VDC (UPS DC sections operating below 600 V are typically ungrounded/floating, while those over 600 V are typically high-resistance center-tap grounde

35、d for safety reasons). These larger UPS may have a single large vented (flooded/wet cell) lead-acid battery string, or multiple parallel VRLA strings. Similar to the medium-sized UPSs, these larger UPS have one or more inverters. They typically have 3-phase 480 VAC input and output. Some UPS systems

36、 are modular in design, meaning that there are multiple inverters (see Figure 4.5 for one such example, although this type of internal redundancy comes in many forms and configurations), and possible multiple rectifiers (typically in a configuration where loss of a single inverter, rectifier, etc. w

37、ill not cause loss of the load). In these cases, the UPS may be capable of putting inverters and/or rectifiers into “sleep” mode so that the remaining ones that are “on” operate at a higher point on the efficiency curve (see Figure 5.1). Figure 4. 5 Example of One Type of UPS System with Internal n+

38、1 Redundancy 5 Metric Definition 5.1 Preamble For the evaluation of UPS energy efficiency, not only is it necessary to know the operating mode (VI, VFD, or VFI), it is necessary to consider normal operating conditions with regard to loading of the UPS. In other words, ATIS-0600015.xx.2009 9 the 97%

39、measured peak efficiency of a UPS in VFI mode at 75% loading may be a useless measurement to the end user if the UPS normally is only 10% loaded. UPS efficiency varies over the load range. Efficiency will be 0% at no load, achieve peak efficiency and drop off at max load. The rise to peak efficiency

40、 varies by technology. Newer UPS typically have higher efficiency curves. See Figure 5.1 for generic examples of UPS efficiency curves. Figure 5.1 Efficiency vs Loading Curves for Two Different UPSs Operating in VFI Mode Most UPS sold are to the consumer market, fall in the small size range ( 10 kVA

41、), and the UPS system is non-redundant (see Figure 5.2 for an example of a 1N UPS power feed architecture). However, telecommunications carriers typically buy medium and large-sized UPS to serve their critical AC-powered larger loads (if they are in a DC-centric building, such as a central office an

42、d the critical AC loads are relatively small, they may use an inverter powered from the nominal -48 VDC plant) from redundant medium and large-sized UPS systems. Redundancy for critical systems (primarily HVAC and power) is defined in the Uptime Institutes Tier Standards. These standards define four

43、 different levels of critical system redundancy (or lack thereof). These are known as Tiers I, II, III, and IV (1, 2, 3, and 4), with Tier IV being truly 100% redundant (also known as 2N a 2N power architecture example is depicted in Figure 5.3) on all critical systems, including being fed from two

44、separate commercial AC substations. From a UPS efficiency/loading perspective, we are concerned with whether the UPS systems AC power feed(s) to end-use equipment are non-redundant (Tier I), fully redundant (Tier IV), or somewhere in between (”Catcher” systems, or N+1 architectures, examples of whic

45、h are depicted in Figures 5.4 and 5.5, respectively). ATIS-0600015.xx.2009 10 Figure 5.2 1N UPS Power Feed Architecture Example Figure 5.3 2N UPS Power Feed Architecture Example ATIS-0600015.xx.2009 11 Figure 5.4 Catcher System UPS Power Feed Architecture Example Figure 5.5 N+1 UPS Systems Power Fee

46、d Architecture Example ATIS-0600015.xx.2009 12 Even in a non-redundant UPS architecture, wise users generally do not load their UPS to more than 80% before up-sizing it, or adding another UPS. This is based partially on wise planning practices, but partially on overcurrent protector sizing rules fou

47、nd in the NEC. In spite of the fact that wise users never fully load their UPS, the U.S. EPA Energy Star calculation includes significant weighting for smaller UPS at 100% loading. Table 5.1 EPA UPS Energy Star Loading Assumptions for Calculating Average Efficiency Because the Energy Star ratings ar

48、e skewed toward small UPS users, inordinately weighted toward higher loading percentages at which large telecom users would not generally operate, and dont differentiate weightings for differing operating modes for medium and large size UPS, the TEER ratings of the following subclauses skew the weig

49、hting of the various loadings more toward typical telecom UPS operating loads, and are specific to the various operating modes. 5.2 UPS TEER If we define the efficiency as the ratio of power dissipated by the load and power drawn from the source (nullPOUT/PIN), then it is straightforward to calculate the UPS TEER from the equations below. nullnullPnullnullnullPnullnull5.2.1 Determining the TEER value for a Single-Source UPS Operated in Off-Line/Eco Mode Small UPS serving less-critical loads are sometimes operated in off-line/Eco (economy) mode (VFD) to m