WP#63 - Free Power Quality

Overview

The Green Grid's WP#63 is dated 13 March 2015 and introduces the concept of Free Power Quality. The concept is an analogue of free cooling: where free cooling exploits the coolness of outside air, here the power quality supplied by the utility is exploited. The aim is to minimise the number of power conversion stages while maintaining the required reliability. The paper is available through a registration-based download, and this summary relies only on the public page.

The paper searches the literature on the quality of utility-supplied power and draws opportunities and challenges from it. The idea is that where utility power of good enough quality is available, over-provisioned UPS equipment and unnecessary conversion stages could be removed. Because conversion stages add both capital cost and operating losses, reducing them promises an efficiency gain. One point the paper stresses is that adoption depends on perceived performance as well as technical suitability. Acceptance rests on perceptions of reliability, power quality and power arbitrage. In other words, the success of the approach is a matter not only of numbers but also of operators' and IT teams' confidence in it.

The limit of this record is that it rests on the abstract only and does not relay quantitative results. The paper is followed by WP#69 on ride-through data of IT power supplies. For the designer, the practical meaning is that the efficiency gain of reduced-conversion topologies can be adopted only when weighed against the ride-through margin of the IT power supplies.

Key points

1. Dated 13 March 2015.
2. The concept is analogous to free cooling: using available utility power quality.
3. Aims to minimise power conversion stages while maintaining required reliability.
4. Includes a literature search on the quality of utility-supplied power.
5. Acceptance depends on perceived performance for reliability, power quality and power arbitrage.
6. Identifies opportunities and challenges; targets removal of over-provisioned UPS equipment.
7. Followed by WP#69 on ride-through data.

Using it in design

• Offer a reduced-conversion topology scenario.
• Show that scenario's efficiency gain against the ride-through margin of the IT PSUs (see WP#67 and WP#69).
• Where utility power quality data exist, mark the scenario as an option backed by that data.
• Present the reduction in conversion stages together with a risk assessment so the reliability requirement is preserved.

Who should read it

Electrical designers working on UPS topology, power chain efficiency and utility power quality.

Publication details

Authors

George Navarro; Dusty Becker; Ian Bitterlin; Bill Campbell; Don Goddard; Harry Handlin; Pam Lembke; David Loucks; Stephen McCluer; David Mohr; Bob Schuerger; Jim Spitaels; Charlie Swiontek; Henry Wong

Publisher

The Green Grid

Year

2015

Document number

WP 63

Document language

English

Source type

Industry body

Access

Citation only

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation