Comparing IEC 61850 vs. Traditional Monitoring, Protection and Control Solutions in Large Data Centers

Overview

The basis is Schneider reference design RD107: 4 data halls x 2.8 MW = 11.2 MW IT, 15 MVA total, two utility incomers in main-tie-main, centralized MV generators with 2 gensets per generator switchboard designed N+2. The closed-loop arrangement calls for differential and directional protection and automatic transfer logic. IEC 61850 replaces hardwired inter-trips and remote I/O with supervised GOOSE messages over a PRP/MRP redundant network, at the cost of more upfront engineering and validation.

GOOSE messages are fast (under 4 or 10 ms), self-monitored multicast. IEC 62439 PRP and HSR recover the network in under 1 ms with zero packet loss, which RSTP cannot meet; the study used PRP plus an MRP backbone ring. The Modbus/TCP alternative used an RSTP ring of 8 Ethernet switches with hardwired relay-to-PLC signals for blocking schemes. Hardwired inter-trip signals are not supervised, so wiring failures go unnoticed until a protection operation is needed, whereas GOOSE links raise an alarm on communication faults.

IEC 61850 reduces on-site work time 2-3x and the LV-section footprint of MV switchboards by 5%, while engineering studies and validation/FAT are about 30% higher. KPI scores (IEC 61850 versus Modbus/TCP): safety 0, CapEx subtotal 0, reliability +2, scalability +3, time to market +1, footprint +1, operation and maintenance +5, total +12. The authors limit applicability to large sites (10 MW IT or 15 MVA total or more), complex non-radial MV topologies, multi-site repeated designs, fast deployment, frequent evolution, or advanced functions such as microgrid, load shedding and load balancing. Related standards are IEC 61850, IEC 62439-3, IEC 62439-2 and IEEE 802.1D.

Key points

1. RD107: 4 x 2.8 MW = 11.2 MW IT, 15 MVA, two main-tie-main incomers, 2 gensets per MV generator switchboard, N+2.
2. GOOSE: under 4 or 10 ms, self-monitored multicast.
3. PRP and HSR recover in under 1 ms with zero packet loss; RSTP cannot.
4. Modbus/TCP alternative: 8-switch RSTP ring and hardwired signals.
5. IEC 61850 cuts site work 2-3x and LV-section footprint 5%; engineering and validation/FAT about 30% higher.
6. KPI total +12: reliability +2, scalability +3, operation and maintenance +5.
7. Hardwired inter-trips are unsupervised; GOOSE alarms on communication faults.
8. Applicability: 10 MW IT or 15 MVA and up, complex MV topology, repeated designs or functions like load shedding.

Using it in design

• Add a protectionControlScheme attribute to the MV module: hardwired_plc_modbus, iec61850_station_bus, iec61850_process_bus.
• Suggest IEC 61850 when IT load is 10 MW or more or the facility 15 MVA or more with MV-centralized generation or closed-loop or daisy-chain MV topology.
• When IEC 61850 is chosen, require PRP or HSR (IEC 62439-3) for the protection network and flag RSTP as non-compliant for GOOSE inter-tripping.
• Add an SCD-file baseline and pre-FAT simulation to the commissioning checklist, and assume about 30% more engineering/FAT but 2-3x shorter site work in schedules.

Who should read it

Electrical designers and commissioning engineers choosing the MV protection and control architecture of large data centres.

Related standards

• IEC 61850
• IEC 62439-3
• IEEE 802.1D (RSTP)
• IEC 62439-2 (MRP)

Publication details

Authors

Brice Martinot-Lagarde; Julien Moreau

Publisher

Schneider Electric

Year

2021

Document number

WP 285

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