GRIDCON® Active Filter
Active harmonic filters for clean power grids
Modular active harmonic filters for any application: The flexible design of our GRIDCON® ACF X-Wire filters enables operation in 3-wire and 4-wire applications. A configuration suitable for 4-wire operation – with a mandatory neutral wire connection – is needed to filter single-phase loads, and protects against neutral conductor overloads. Common applications are in 208 V and 400 V networks. In most industrial applications, a 3-wire configuration works best as the design can be optimized for symmetrical loads and no neutral conductor needs to be accounted for.
Our filter for heavy-duty applications is therefore called GRIDCON® ACF 3-Wire and is only available in this configuration. The robust design enables it to operate in the most challenging environments, where it can be used to improve the voltage quality in networks with nominal voltages of 440 V, 480 V, 525 V, 600 or 690 V – Or even reduce harmonics in medium voltage networks via a transformer. The latter plays a vital role in achieving grid code compliance for industrial sites at the point of common coupling with the public grid.
GRIDCON® ACF 3-Wire systems with liquid cooling are optionally available.
Your Advantages at a Glance
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Voltage control enables sensorless operation without current transformer, often with better results
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Automatic compliance with permissible harmonic limits according to EN 50160 / IEC 61000 / IEEE 519 standard
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Broadband filtering prevents additional heating of equipment by selectively reducing voltage distortion up to the 51st harmonic
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Flexibility – Our portfolio offers solutions for 3-wire and 4-wire applications, top or bottom cable entry and direct connection to voltage levels up to 690V
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High dynamic compensation of reactive power (capacitive and inductive), harmonics and flicker
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High power density in a small space: Up to 600 A possible in one cabinet
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Modularity enables easy expansion and adaptation
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Low-loss: Lower power costs through efficient design and 3-level technology
Product Information
Variable Frequency Drives (VFDs) are a common load in in various industries as they are more efficient and offer enhanced control compared with directly connected motors. VFDs emit harmonic currents, which cause distortion in the mains voltage. The harmonic content of a waveform is commonly expressed as Total Harmonic Distortion (or THD for short). For a Variable Frequency Drive with a typical 6-pulse layout the Total Harmonic Distortion of the current can exceed 40%.
Active filters are the established solution for flexibly and safely reducing harmonics. How do they work? You can think of them as a controlled current source. This compensates for disruptions in the network by feeding in a current of exactly the required frequency and amplitude. The illustrations shows the distorted load current in red. This is measured by the active harmonic filter and a compensation current – in blue – of the same amplitude but with a 180° phase shift leads is injected. As a consequence, the grid current (green) flowing through the transformer is free of harmonics. Alternatively, our active harmonic filters can also work sensorless – i.e. without a current transformer – based on a voltage measurement. This voltage control mode makes it possible, in particular, to compensate for network pre-distortion.
The 3-level topology of GRIDCON® ACF is based on twelve IGBTs, whereas conventional 2-level active filters only comprise of six. The special circuitry halves the voltage load of the power semiconductors. On the one hand this results in lower losses and on the other hand enables use in grids with a higher rated voltage. The DC link voltage is also higher which allows higher peak currents to be generated, which is essential for filtering harmonics with a high bandwidth. Another benefit of the 3-level technology is the lower ripple of the output current compared with the 2-level architecture. The split DC link and the larger number of IGBTs result in an additional third inverter state at the output. This can be used to make the line filter and EMC filter more compact with the same switching frequency and thereby reduce losses.
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Variable Frequency Drives (VFDs) are a common load in in various industries as they are more efficient and offer enhanced control compared with directly connected motors. VFDs emit harmonic currents, which cause distortion in the mains voltage. The harmonic content of a waveform is commonly expressed as Total Harmonic Distortion (or THD for short). For a Variable Frequency Drive with a typical 6-pulse layout the Total Harmonic Distortion of the current can exceed 40%.
Active filters are the established solution for flexibly and safely reducing harmonics. How do they work? You can think of them as a controlled current source. This compensates for disruptions in the network by feeding in a current of exactly the required frequency and amplitude. The illustrations shows the distorted load current in red. This is measured by the active harmonic filter and a compensation current – in blue – of the same amplitude but with a 180° phase shift leads is injected. As a consequence, the grid current (green) flowing through the transformer is free of harmonics. Alternatively, our active harmonic filters can also work sensorless – i.e. without a current transformer – based on a voltage measurement. This voltage control mode makes it possible, in particular, to compensate for network pre-distortion.
The 3-level topology of GRIDCON® ACF is based on twelve IGBTs, whereas conventional 2-level active filters only comprise of six. The special circuitry halves the voltage load of the power semiconductors. On the one hand this results in lower losses and on the other hand enables use in grids with a higher rated voltage. The DC link voltage is also higher which allows higher peak currents to be generated, which is essential for filtering harmonics with a high bandwidth. Another benefit of the 3-level technology is the lower ripple of the output current compared with the 2-level architecture. The split DC link and the larger number of IGBTs result in an additional third inverter state at the output. This can be used to make the line filter and EMC filter more compact with the same switching frequency and thereby reduce losses.
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