Passive Shunt Active Filter for Power Quality Enhancement

The passive shunt active filter is a current filtering device utilized in power systems to enhance current quality through shunt connection and filtering techniques. Its primary function involves injecting compensatory currents to counteract harmonics and interference within the electrical network, thereby reducing current distortion. This filter typically combines passive components (inductors, capacitors) with active circuitry (power electronics switches, control algorithms) to achieve optimal filtering performance. In implementation, the control system often employs instantaneous power theory (p-q theory) or synchronous reference frame (d-q transformation) algorithms to detect harmonic components in real-time. The active component generates compensating currents using PWM-controlled inverters, while passive elements provide fundamental harmonic filtering and energy storage. Widely applied in power systems, passive shunt active filters deliver stable and reliable current quality, effectively addressing harmonic pollution and interference issues through coordinated passive-active operation. Advanced implementations may incorporate DSP or FPGA-based controllers executing FFT analysis for harmonic detection and predictive current control algorithms for dynamic compensation.