UPS Topologies and Multi-Module Configurations
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Transcript of UPS Topologies and Multi-Module Configurations
UPS Topologies and Multi-Module Configurations
IEEE IAS SectionAtlanta GA
November 17, 2008
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Agenda
UPS TopologiesLine Interactive UPSDelta Conversion UPSDouble Conversion UPSRotary UPS
UPS Design Market Drivers
UPS Components
Multi-Module UPS Configurations
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Critical Power System
ATS
TVSS
Power Quality Distribution
PDU
Generation
Paralleling Switchgear
Critical Load
UPSServersStatic
Switch
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Line Interactive UPS
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UPS Topologies – Line Interactive
Line Interactive
Runs on AC power from Utility and switches to Inverter if Utility source power quality is not within predetermined tolerance. Provides some surge protection.
Benefits – very efficient due to minimizing inverter run time
Disadvantages – limited surge protection
Application – Single computer or single rack
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Delta Conversion
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This Line Interactive system carries the load by using both the utility line by means of a Line Conditioner (Course Regulation) and two converters (Actually two inverters for Fine Regulation & Battery Charger).
This topology can regulate the load voltage by manipulating the secondary winding of the series t-former using the Series Converter.
Advantages• System does not go on battery for voltage fluctuations.• System efficiency is higher in normal mode.
Disadvantages• The unit needs two inverters, less reliability.• It circulates more ripple current to the batteries.• If the utility frequency goes out of tolerance, the unit must go on batteries.
Delta Conversion
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Double Conversion UPS
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UPS Topologies – Double Conversion
Double ConversionRectifies AC power into DC and then converts the DC back to AC. Provides clean power, completely isolated from the Utility during normal operation.
Benefits – No interruption of Power; Protects load from Utility spikes and Surges
Disadvantages – Greater losses than Line Interactive design
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Rotary UPS
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UPS Design Key Market Drivers
Reliability – The 5 “9’s” - 99.999% up time
EfficiencyEPA InfluenceGreen Grid
Server TechnologyVoltageOutage Ride Through
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Efficiency
Line Interactive UPS ~98% efficient
Double Conversion ~ 92% to 94% efficient
Methods to improve UPS efficiencyEliminate Input and Output Transformers“ECO” mode -Line interactive mode of operation
Data Center Efficiency TrendsEliminate PDU transformersElectrical Distribution Voltages
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ECO Mode Overview
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Server Technology
Server VoltagesToday –120VAC - 240VAC
600V or 480V distribution with PDU transformers400V distribution without PDU transformers
Future – 277 VAC? ; 480VAC?
Server Power Outage Ride ThroughCEMBA Curve – Now the “ITIC” CurveKey Factor for “ECO” mode.
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CBEMA-ITIC Curve for Double Conversion UPS
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UPS Components
RectifiersSCR or IGBTSCR – 6 Pulse and 12 Pulse
InvertersIGBT with PWM
Static Switch Module
TransformersInput TransformerOutput Transformer
FiltersInput Harmonic Filters
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Rectifiers
•Rectifiers can be programmed to sequentially ramp up
IGBT Rectifier – Clean InputHigh power sinusoidal rectification – low harmonics, limited need for filters
SCR Rectifiers 6 Pulse – ~30% THD without filters – 7% with 5th Harmonic Filter<5% with 5th and 11th filter
12 Pulse – reduces harmonics by using parallel rectifiers with a phase shift ahead of one rectifier – requires input transformerLower efficiency than 6 Pulse
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6 Pulse Current Input
THD without
filter
THD with
filter
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12 Pulse Rectifiers
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750 kVA - 6P vs 12P Rectifier – Energy Efficiency
Percentage load
6-Pulse - no Xfrmr
12-Pulse w/xfrmr
25% 92.8 % 91.8 %
50% 94.2 % 93.3 %
75% 94.2 % 93.2 %
100% 93.6 % 92.4 %
Efficiency
Difference
1.0 %
0.9 %
1.0 %
1.2 %
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Inverters
Converts DC power into AC using IGBTs and PWM
Several different methods to implement PWM
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Static Switch Modules
Static Switch Module consists of breaker or contactor in series with back to back SCRs.
Static Switch modules can be continuous duty or momentary rated. Momentary rated Modules have a breaker or contactor in parallel.
Continuous duty is required for ECO mode operation.
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Input Isolation Transformer Input Isolation Transformer – required for 12 Pulse Rectifier
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Output Transformer- Isolates load from inverter
- Provides greater protection to load during inverter failure
- Transformer MTBF > IGBT MTBF
UPS Output Transformer
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Input Filters
5th Harmonic Cancellation
•The filter is designed to cancel the current distortion that is most present on the 5th harmonic.
Power Factor Correction•The input filter also raises the input pf to approximately 0.93 with addition of capacitors. This will allow the generator to operate more efficiently delivering more real power
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Multi-Module UPS Configurations
Paralleling UPS ModulesCapacity or RedundancyCentralized BypassDistributed Bypass
Typical Parallel UPS ConfigurationsIsolated RedundantParallel RedundantDistributed RedundantSystem plus System
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Parallel for Capacity
Multiple units = NNot recommended for a N System (single
system)Frequently used for System + System (N+N)
MTBF impactParallel for capacity reduces MTBF valueApproximately half the MTBF of a single unit
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Centralized Bypass
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Distributed Bypass
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Centralized Bypass Cabinet
Distributed Bypass Configuration does not need this gear lineup
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Parallel UPS Configurations
Isolated Redundant
Parallel Redundant
Distributed Redundant
System plus System
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Isolated Redundant
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Parallel Redundant
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Distributed Redundant
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System + System
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Questions?
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Contact Information:
Harry HandlinGE Power QualitySystems EngineerP 205-789-7479E [email protected]