Power System Architectures for the Commercial Buildings – Part Five


In the previous Topic; Power system architectures for the commercial buildings – Part Four, I explained the forth type of Power system architectures for the commercial buildings which was “High-rise building, type 3: Transformers at remote location” and today I will explain the fifth type; High-rise building, type 4 & 5: Distributed supply, cables/Busbars” as follows.

You can also review previous topics about electrical design requirements for commercial buildings for good following-up:




High-rise building, type 4 & 5: Distributed supply, cables/Busbars


Conditions for using this power system architecture: 


1- The max. Number of floors for this power system architecture (i) must be (i >20).

Note: All buildings have number of floors > 4 are high rise buildings.


2- If the floor area of the building ≤ 1,000 m2 & the total area of the building > 20,000 m2

3- If the power density of the building loads have the following limits:
  • Power required ≥ 2,000 kW. 
  • Segmentation of power required 80 % utilized area (i.e. functional area like Offices, Briefing rooms, Data center, Canteen kitchen with casino, Heating/ventilation/air conditioning, Fire protection and Transport) And 20 % side area (i.e. shafts, fountains, green area, sky lighting area and etc.).

4- If the power supply needed for the building have the following requirements:
  • Supply types 100 % total power from the public grid; (Supply of all installations and consumer Devices available in the building).
  • 10–30 % of the total power for safety power supply (SPS) from generators; (Supply of life-protecting facilities in case of danger, e.g.: Safety lighting, Elevators for firefighters, Fire-extinguishing equipment).
  • 5–20 % of the total power for uninterruptible power supply (UPS); (Supply of sensitive consumer devices which must be operated without interruption in the event of a NPS failure / fault, e.g.: Tunnel lighting, airfield lighting, and Servers / computers and Communications equipment).


Example for using “High-rise building, type 4 & 5: Distributed supply, cables” power system architecture:

We have a building with 3,600 KVA total load power, 25 floors and floor area 1,000 m2 with total area 25,000 m2.

Solution selected for this building is using the “High-rise building, type 4: Distributed supply, cables” power system architecture as follows:

Design solution
Advantages of this solution
Benefits from this solution
Using distributed transformers Splitting into two supply sections


Short LV cables, low power losses, reduction of fire load

Economical, simplified fire protection

Radial network

Transparent structure

Easy operation and fault localization

(2)Transformer module with 3 × 630 kVA each

Voltage stability, lighter design

Optimized voltage quality, economical

Redundant supply unit:
– Generator 500 kVA (30 %) (the smaller the generator, the greater the short-circuit current must be compared to the nominal current)
– UPS 2x250 kVA (15 %)

Supply of important consumers on all floors in the event of a fault, e.g. during power failure of the public grid
Increased reliability of supply

Safety power supply

Safety power supply in acc. With DIN VDE 0100-718

Supply of sensitive and important consumers

Uninterruptible supply of
consumers, e.g. during power failure of the public grid

Use Medium-voltage switchgear from type SF6 gas-insulated


Compact Design; independent of climate

Minimized space requirements for electric utilities room; no maintenance required

Use Transformer from type cast-resin with reduced losses

Low fire load, indoor installation

Economical

Use Low-voltage main distribution with  central grounding point
( which splitting of PEN in PE and N to the TN-S sys (4-pole switches for connecting the LVMDs)


EMC-friendly power system

Protection of telecommunications
Equipment from electromagnetic
interference (e.g. to prevent lower transmission rates at communication lines)

Use Wiring / main route as cables

Central measurement of current, voltage, power, e.g. for billing, cost center allocation

Cost transparency, cost saving

 
For this example the power system architecture will be as follows:
“High-rise building, type 4: Distributed supply, cables” power system architecture

 
Where:
NPS
Normal power supply
FD
Floor distribution boards
PCO
Power company or system operator
FF
Firefighters
HVAC
Heating – Ventilation – Air conditioning
MS
Medium-voltage switchboard
LVMD
Low-voltage main distribution
SPS
Safety power supply
UPS
Uninterruptible power supply
z
Power monitoring system


The same power system architecture can be used but with Wiring / main route as busbars and in this case it will be called as “High-rise building, type 5: Distributed supply, busbars” And the Solution selected for this building is using the “High-rise building, type 5: Distributed supply, Busbars” power system architecture as follows:


Design solution
Advantages of this solution
Benefits from this solution
Using distributed transformer Splitting into two supply sections


Short LV cables, low power losses, reduction of fire load

Low costs

Radial network

Transparent structure

Easy operation and fault localization

(2) Transformer module with 3 × 630 kVA each

Optimized voltage stability

Optimized voltage quality, economical

Redundant supply unit:
– Generator 500 kVA (30 %) (the smaller the generator, the greater the short-circuit current must be compared to the nominal current)
– UPS 2x250 kVA (15 %)

Supply of important consumers on all floors in the event of a fault, e.g. during power failure of the public grid
Increased reliability of supply

Safety power supply

Safety power supply in acc. With DIN VDE 0100-718

Supply of sensitive and important consumers

Uninterruptible supply of
consumers, e.g. during power failure of the public grid

Use Medium-voltage switchgear from type SF6 gas-insulated


Compact Design; independent of climate

Minimized space requirements for
electric utilities room; no maintenance required

Use Transformer from type cast-resin with reduced losses

Low fire load, indoor installation

Economical

Use Low-voltage main distribution with  central grounding point
( which splitting of PEN in PE and N to the TN-S sys (4-pole switches for connecting the LVMDs)


EMC-friendly power system

Protection of telecommunications
Equipment from electromagnetic
interference (e.g. to prevent lower
transmission rates at communication lines)

Use Wiring / main route as Busbars to the sub-distribution boards

Low fire load, flexible power distribution

Safety, time savings during restructuring

Few outgoing feeders in the distribution, small distribution


Minimized space requirements for
electric utilities room

Small, minimized rising main busbar

Less space requirements for supply lines

Easy installation

Cost reduction



By using busars and for this example the power system architecture will be as follows:

“High-rise building, type 5: Distributed supply, Busbars” power system architecture
 
Where:  
NPS
Normal power supply
FD
Floor distribution boards
PCO
Power company or system operator
FF
Firefighters
HVAC
Heating – Ventilation – Air conditioning
MS
Medium-voltage switchboard
LVMD
Low-voltage main distribution
SPS
Safety power supply
UPS
Uninterruptible power supply
b
4-pole switch for connecting the LVMDs
z
Power monitoring system



In the next Topic, I will show complete comparison between these power system architectures for commercial buildings. So, please keep following




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