Grid-Interactive Data Centers: Enabling Decarbonization and System Stability

Overview

The paper explains that low-inertia grids need fast reserves to hold frequency and defines the services involved: frequency containment reserves (FCR-D, FCR-N), fast frequency response (FFR) and PJM RegD. Required reaction time ranges from below one second for FFR to a few seconds for FCR-D, and the response can be static or droop-based dynamic. PJM's AGC sends a RegD regulation signal every two seconds, and payment depends on tracking accuracy.

A modern bidirectional UPS is shown sharing load between grid and battery or exporting power. Field cases cover the Nordics, Ireland and a Microsoft US site; in the Irish case the UPS delivered a static 25 kW response triggered when frequency fell below 49.70 Hz. Battery state of charge is split into a reserve for critical load and a band for grid services, and on alarms or lost external signals the UPS fails safe to load-protection mode.

On economics, about 50% of the cost of a BESS above 1 MW is batteries and converters; the rest is grid connection, property and building, which a data-centre UPS already has. European ancillary-service revenues range from tens of thousands up to over EUR 100,000 per MW per year.

Battery degradation depends on the market's activation pattern: lead-acid batteries may be unsuitable for many ancillary markets, and the degradation impact is small in Irish and Nordic FFR but significant in PJM or continental continuous regulation.

Key points

1. Required reaction time ranges from below one second (FFR) to a few seconds (FCR-D); response can be static or droop-based dynamic.
2. PJM's AGC sends a RegD signal every two seconds, and payment depends on tracking accuracy.
3. Irish field case: the UPS delivered a static 25 kW response when frequency fell below 49.70 Hz.
4. About 50% of the cost of a BESS above 1 MW is batteries and converters; the remainder is grid connection, property and building, which a data-centre UPS already has.
5. European ancillary-service revenues range from tens of thousands up to over EUR 100,000 per MW per year.
6. Battery SoC is split into a critical-load reserve and a grid-service band; on alarms or lost signals the UPS fails safe to load-protection mode.
7. Lead-acid may be unsuitable for many ancillary markets; degradation is small in Irish/Nordic FFR but significant in PJM or continental continuous regulation.

Using it in design

• When sizing UPS batteries, model a grid-services band on top of the required autonomy.
• Restrict continuous-regulation services to Li-ion or similar high-cycle chemistries.
• Catalogue the UPS bidirectional rectifier and export capability, built-in frequency measurement and supported service types (FFR, FCR-D, FCR-N, RegD).
• Show the reserved backup energy separately in runtime reports.

Who should read it

Hyperscale and colocation designers considering grid-service revenue from UPS battery energy, and the decision makers behind it.

Related standards

• IEC 62040-3
• ENTSO-E Network Codes

Publication details

Authors

Janne Paananen; Ehsan Nasr

Publisher

Eaton

Year

2021

Document number

WP153031EN

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

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

Citation