BY91-APF/50A-0.4/4L-B Harmonic Suppression Automatic Compensation Active Harmonic Filter

Model Meaning

Specifications of BY91-APF/50A-0.4/4L-B Active Harmonic Filter

Overview of BY91-APF/50A-0.4/4L-B（APF）

The BY91-APF/50A-0.4/4L-B is a cutting-edge Active Power Filter (APF) engineered to address harmonics in power and enhance electrical supply reliability in 3-phase power systems. Utilizing Shunt Active Power Filter Working principles, it performs real-time harmonic analysisto detect distortions (2nd to 50th order) caused by nonlinear loads, such as VFDs and LED lighting. The current source active filter injects precise compensating currents to achieve harmonic mitigation, reducing THD below 5% and stabilizing 3-phase voltage fluctuations. Its dynamic reactive power compensation capability corrects three-phase imbalance compensation by autonomously balancing currents in 3-phase electric grids, ensuring optimal power quality even under asymmetric load conditions.The hybrid active and passive filters for harmonics combine rapid response with robust anti-harmonic performance, while intelligent control algorithms enable three-phase unbalanced adaptive correction and low-voltage reactive power compensation. Integrated real-time monitoring tracks low power electricity parameters, allowing adaptive adjustments to dynamic reactive power compensation control for high-efficiency energy-saving operations. Designed for low-voltage power environments, the low-voltage filter module features anti-interferenceshielding to withstand electromagnetic noise in industrial and urban settings. This power quality filter not only resolves power quality harmonics but also aligns with IEEE 519 standards, making it indispensable for factories, data centers, and renewable energy systems.

The BY91-APF/50A-0.4/4L-B excels as a power harmonic filter across diverse sectors, from manufacturing plants to solar farms. In industrial facilities, its electrical harmonic filterneutralizes harmonics from heavy machinery, while automatic harmonic filter functionality adapts to load variations, ensuring stable 3-phase power voltage. For renewable energy systems, the shunt active power filter mitigates harmonic resonance caused by inverters, performing harmonic compensation to stabilize power low voltage grids during intermittent generation.The active harmonic filter working mechanism integrates harmonic filter working principlewith intelligent control to optimize power filtering efficiency. By continuously analyzing 3-phase electric parameters, the system executes three-phase unbalanced adaptive correction, resolving imbalances in 3-phase power distribution networks. The dynamic reactive power compensation control minimizes line losses and enhances low power voltage stability, reducing energy waste by up to 30%. Its compact design suits space-constrained installations, such as commercial buildings with low power electricity infrastructure, while anti-interference technology ensures reliability in electromagnetically harsh environments.As a leader in active filters in electronics, BaoYu Holdings delivers unmatched harmonic suppression and electrical supply protection. The BY91-APF series not only extends equipment lifespan but also supports global sustainability goals through high-efficiency energy-savingperformance. Whether tackling harmonics in power or optimizing power quality, this anti-harmonic filter sets the benchmark for modern energy management solutions.

BY91-APF/50A-0.4/4L-B（APF）Main Features

• The parallel active power filter working technology can realize real-time harmonic analysis and suppression, reduce power supply harmonics, and ensure the stability of three-phase power supply voltage.
•  Dynamic reactive power compensation stabilizes the low voltage grid while correcting three-phase unbalance compensation through intelligent control algorithms.
• Hybrid active and passive harmonic filters provide strong harmonic mitigation to less than 5% THD, improving power quality.
• Automatic harmonic filtering function adapts to load changes, performs harmonic compensation on three-phase power systems, and monitors accuracy in real time.
• Current source active filter design ensures efficient power filtering and low voltage reactive power compensation, minimizing energy losses in low power environments.4
• Three-phase unbalance adaptive correction balances the three-phase power distribution and solves the imbalance caused by asymmetric loads or renewable energy integration.
• Anti-interference shielding and electrical harmonic filtering protect power supplies in industrial and urban environments from electromagnetic noise.
• High efficiency and energy saving performance, with dynamic reactive power compensation control, reduces operating costs, and complies with power quality harmonic standards.

Working Principle BY91-APF/50A-0.4/4L-B（APF）

Shunt Active Power Filter Working Principle for Harmonic Suppression and Dynamic Reactive Power Compensation
BY91-APF/50A-0.4/4L-B adopts the shunt active power filter (APF) topology to solve the harmonic and reactive power imbalance problems in three-phase power systems. By connecting in parallel with the grid, the APF can detect the harmonic currents generated by non-linear loads (such as industrial drives, inverters) by using the fast Fourier transform (FFT) algorithm for real-time harmonic analysis. The APF then injects compensation currents of equal amplitude but opposite phase to neutralize the harmonics, thereby achieving harmonic suppression and reducing THD from 22% to below 1.6%. At the same time, the APF performs dynamic reactive power compensation by adjusting the output to maintain unity power factor, thereby optimizing power quality and reducing energy losses. The three-phase four-wire design ensures balanced operation in the low-voltage system (0.4 kV) and solves the three-phase imbalance problem through an adaptive correction algorithm. Key components include a bidirectional AC/DC converter for capacitor voltage regulation and a PWM controlled inverter for precise current injection, ensuring high energy efficiency and compliance with low-voltage power standards.
Intelligent Control and Adaptive Correction in 3-Phase Systems
The active harmonic filter integrates an intelligent control system and a DSP/FPGA processor to achieve real-time monitoring and adaptive adjustment. It uses anti-interference signal processing technology to dynamically track harmonic distortion and three-phase imbalance in the three-phase power grid. The control strategy combines the instantaneous reactive power theory (pq theory) and the synchronous reference frame (SRF) method to generate accurate compensation signals even in the presence of grid distortion and negative or zero-sequence components. For low-voltage filter applications, the APF's automatic harmonic filtering mode adjusts the compensation priority according to load changes to ensure stability during transient events. In addition, its three-phase unbalanced adaptive correction function redistributes the neutral current in the three-phase four-wire system, thereby reducing the risk of overheating of transformers and cables. This dynamic reactive power compensation control enhances grid resilience while supporting power supply reliability in industrial and commercial environments.
Hybrid Topology for Enhanced Power Quality and Efficiency
The BY91-APF series combines active and passive harmonic filters in a hybrid design to optimize its performance in low-power power environments. Current source active filter modules work in conjunction with passive LC filters to suppress high-order harmonics (e.g. 5th, 7th, 11th) while minimizing switching losses. The power harmonic filter uses real-time monitoring sensors to detect voltage sags, swells, and frequency fluctuations, and triggers instantaneous compensation through IGBT-based inverters. For harmonic compensation in HVDC transmission systems, APF separates reactive power supply and filtering tasks, reducing initial costs compared to traditional passive solutions. Its efficient energy-saving design ensures conversion efficiency of less than 95%, which has been verified by MATLAB/Simulink simulation and hardware-in-the-loop testing. The system's anti-harmonic capabilities can be extended to mitigate interharmonics and subharmonics, making it ideal for renewable energy integration and power quality management in data centers.

Size Informations of  BY91-APF/50A-0.4/4L-B（APF）