APF Principle

Delta’s PQC Series APF is connected in parallel with non-linear loads, and uses one set of current transformers (CT) to detect the load current. It calculates each order harmonic current by FFT algorithms in its DSP microchips and then generates a compensating current with the same amplitude but opposite phase angles to the detected harmonic current, which cancels out the original load harmonics.

The PQC series APF not only eliminates harmonic current from the load side but also mitigates harmonic voltage caused by harmonic currents. The APF system can also improve power factor (PF) and correct load imbalances in the power system.

APF Structure

Delta PQC Series APF has a modular design. Usually, the Delta active power filter system consists of one or several APF modules and an optional Liquid Crystal Monitor & Control Panel (LCM). Each APF module is an independent harmonic filtering system, and users can change the harmonic filtering system rating by adding or removing APF modules.

According to the mounting type, Delta PQC series APF can be divided into Modular APF and Wall-mounted APF.

Modular APF

APF modules and an LCM panel can be embedded in Delta’s standard APF cabinet or a customized cabinet. There are breakers, cable terminals and Surge Protection Device (SPD) in the APF cabinet.

According to cable terminal type, a modular APF can be divided into two types:

• Draw type modular APF (hot-swappable)
• Fixed type modular APF (not hot-swappable)

Wall-mounted APF

Delta’s Wall-mounted APF can be installed on a wall, which is suitable for low rating applications, and an optional LCMpanel can be fixed on the all-mounted APF according to customer requirements.

FEATURES

• Multifunctional: Harmonic, reactive power and imbalance compensation
• High harmonic filtering rate: Up to 98%
• Excellent reactive compensation: High speed, Precise (-0.99≤PF≤0.99), Step-less, Bi-directional (capacitive and inductance) compensation
• Excellent imbalance correction: Both negative and zero sequence, mitigates neutral current
• Wide input voltage & frequency range, adapts to tough electrical environments
• Low thermal loss (≤3% of rated APF kVA), efficiency ≥ 97%
• High stability: Infinite impedance to grid, avoids harmonic resonance problems
• Flexible application: Modular design, embedded in standard or customized cabinet
• Easy installation and maintenance: Plug-in installation for APF module replacement and expansion
• Wide capacity range: 50A~525A for a single cabinet, up 10 cabinets in parallel
• Environmental adaptability: -10~50°C temperature, compatible with diesel generator
• Complete protection: Grid Over/Under voltage, APF over current, over temperature, and more. All faults are recorded in the event log, which is convenient for failure analysis