Active Harmonic Filters
2
Consumers of electricity often
suffer from poor power quality
• Machines stop, power packs burn out, and power
outages paralyze the entire company.
– Many consumers used in industrial production cause massive
disruptions in the mains supply.
– In Germany, for example, damages from production downtimes
amount to billions each year. With increasing tendency!
Power Quality – Sources of
disturbances
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 Fast transients on the mains voltage side
Flattening of sine mains voltage
Switching power supplies
Welding machines
UPS
Motor drives
 Converters with controlled rectifiers
 DC controllers for DC drives
 Old AC drives with thyristor power
converter technology
 Induction furnaces
up
to
sev. sec.
3~ asymmetric
1µs
up to
sev. ms
Voltage dip
Slow voltage
changes
Fast voltage Short-term Long-term Flicker
interruption interruption
changes
Intermittent
overvoltage
UL-N
Transient
overvoltage
UL-N
- Frequency
- Harmonic oscillations
- Inter-harmonics
June 2009
- Signal voltages
Power Quality – The effect
• 1-phase: PCs, monitors, printers,
microwave ovens, TVs, electronic
fluorescent lamp ballasts...
Power Quality – The effect
• 3-phase: motor drives, converters, UPS systems,
induction furnaces, welding machines…
Frequency converter: input current
UPS: input current
Frequency converter: current harmonics
UPS: current harmonics
Network disruptions – Common
solutions
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Harmonic compensation
– Passive filters for individual harmonics
(trap filters) or individual non-linear loads
(e.g. for 6-pulse rectifiers)
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Reactive power compensation
– De-tuned capacitor banks
– Dynamically slow
– Resonances may occur
Mains
Medium voltage
Low voltage
These systems can only be designed in a passive manner, i.e.
for a specific error source, and do not actively adapt to the
situation.
Consumers:
- Power converters
- Drives
De-tuned PFC
Principle of operation
mains
compensation current
CTs
load
Principle of operation
mains
compensation current
CTs
neutral
load
Active harmonic filters
• Active compensation of harmonic currents
– Digital control technology with FFT analysis
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Dynamically fast
Entire frequency spectrum compensated up to the 49th order
Application: welding machines, induction furnaces, …
FFT decomposes the current into its frequency components
Possible to individually compensate for each harmonic
Application: continuous loads, all types of motor drives
• Active compensation of reactive power
– Responds with almost no delay and without resonance
– Optionally selectable
Active Connection diagram
Current transformers can be
placed upstream or
downstream of the filter
Network
Uncompensated load
Compensated load
OmniWave Active Dimensioning
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Dimensioning
– Sum up the nominal input currents of the consumers that need
compensation.
– Compensation current: 35% of the nominal input current must be
compensated for (B6 rectifier bridges with 3% AC reactors)
– Objective: <5% THD-I
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Filter selection
– Smaller individual non-linear consumers:
• Group non-linear loads on a sub distribution bus
• Completely compensate them with OmniWave Active
– Large individual non-linear consumers:
• Connect one or more OmniWave Active in parallel
– Total system:
• Completely compensate the installation with one or more OmniWave Active
in a central location
OmniWave Active
Application example: B6-load
OmniWave Active controller „ON“
Response time (example for 2phase welding process)
line current
(max. 110A)
OmniWave Active
current (immediate
response)
Welding current
(max. 280A)
OmniWave Active
Application example: AC drive mix
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Application:
Load type:
Comp. system:
Compensation of harmonic oscillations and reactive power
Motor and converter load in switching operation
PFC (without series reactors)
OmniWave Active
Product range
OmniWave Active 30A/50A (3-wire)
 Wall mounting or cabinet integration possible
 IP54 degree of protection if installed in a cabinet
 ~30% volume compared to tradition active harmonic filters
 Only 47kg
OmniWave Active 30/60A (4-wire)
 Low audible noise emission
 Superior EMC Level
OmniWave Active 100A/120A (3-wire and 4-wire)
 Only slightly larger and heavier than their little brothers
 Most popular type, always the perfect fit
 IP54 degree of protection if installed in a cabinet
 Weight: 105/145kg
OmniWave Active
Product range
OmniWave Active 200A/250A/300A
 Cabinet 800 x 2000 x 600mm (W x H x D)
 3-wire and 4-wire technology available
 IP54 protection degree for industrial use
 Weight: 415/495 kg
 Air cooling, optional water cooling
 Internally encapsulated liquid cooling
 Ambient temperature: 0°C - 40°C continuous,
40°C - 55°C automatic de-rating 2%/K
The industrial model is a real power pack
OmniWave Active
System architecture
OmniWave Active
controller
OmniWave Active
Controller platform
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System architecture:
– Power PC
– eCOS real-time operating system
– Synchronous 12-channel measured value recording, sampling rate 31µs
Standard interfaces:
– ModBus RTU (RS485), ModBus TCP/IP (Ethernet),
CAN digital input/output
– 2 free slots for additional cards
Monitoring:
– Device and module temperatures, precision < 1Kelvin
– Mains voltage and phase
– Asymmetric intermediate circuit
– Failure memory
Housing optimized for EMC
Operating temperature range: -40°C to +55°C
OmniWave Active (50A)
Components
OmniWave Active (300A)
Mechanical design
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System rack:
– 800 x 2000 x 600mm (WxHxD)
– IP54 protection class
– Weight: 415/495kg
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Cooling system:
– Air cooling
(integrated air/water heat exchanger)
– Power loss: 7,500/8,500W
– Optional water cooling
– The acquired process heat can be used
– > OmniWave Active is energy-neutral
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Ambient temperature:
– 0°C – 40°C continuous
– 40°C – 55°C automatic de-rating 2%/K
OmniWave Active (300A)
Cooling system
• Primary cooling:
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Water/air heat exchanger
Fans
Expansion reservoir and pump
Control unit
Coolant: water with Antifrogen
Cooling performance: 6,500/7,500W
• Interior cooling:
– Air/air heat exchanger
– Cooling performance: 1,000W
OmniWave Active (300A)
System concept
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Module units:
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CE, UL mains fuse unit
Mains filter
Converter unit
Intermediate circuit modules
Power output stages
– Notch filter + absorption circuit
– Control platform + HMI
– Measured value recording
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Serviceability:
– Plug & Play module replacement
– MTTR <15min
AHF Viewer
PC user interface
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Based on Windows XP, multi-language interface
Modbus serial line or TCP/IP protocol
Data interface to common office applications
System management
Monitoring functions:
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Oscilloscope
Data logger
Transients monitoring
FFT analysis
Diagnosis, disruption
analysis
Parameterization functions:
– Unit initialization
– Firmware update
OmniWave Active
Features
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Global or selective compensation of specific
harmonics up to the 50th order
Compensation for power factor, cos phi
Multi-language control and display panel
Menu-guided setting and selection of
parameters
AHF Viewer PC operation software
Diagnosis and maintenance system
Status display of current power quality
Remote operation
Can be used with a wide range of common
current transformers
25
OmniWave Active
Features and Benefits
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CE and UL conform
> ready for worldwide use
Fully digital
> state-of-the-art technology
Fastest control
> immediate harmonic compensation
16kHz control cycle with notch filter
> very quiet system
Current transformer can be upstream/downstream of filter
> simple integration
Use of any current transformer
> great flexibility
Any type of device cascading
> cost effective upgrades possible anytime
High overload capability
> excellent dynamic load compensation
High-quality components
> long maintenance intervals, MTBF up to 100,000h
Fast commissioning
> intuitive and easy
Complete PC analysis tool
> online network monitoring
TCP/IP connection
> remote maintenance possible
German engineering
> highest quality and reliability
Worldwide organization
> fast and local support
Plug-and-play
3 simple steps to better power quality
Measure
Determine the supply
points for OmniWave
Active by precisely
measuring the network
load.
Install
Select the suitable
current transformer and
install OmniWave Active.
Configure
Commission OmniWave
Active with just a few
clicks.
 OmniWave Active is easy to cascade
 Up to five OmniWave Active units can be used in parallel
 Filters with different ratings can be combined
Medium Voltage Harmonic Correction
• 1000 kVA Harmonic Correction per
module
• for larger systems add modules to
meet Harmonic requirements
• Voltages up to 33kV