Implementation of Instantaneous Reactive Power-Based Harmonic Detection and Reactive Power Compensation in Grid-Connected Systems

In grid-connected systems, harmonic pollution and reactive power issues can significantly deteriorate power quality. The harmonic detection and reactive compensation technology based on instantaneous reactive power theory enables real-time analysis of harmonic components and reactive elements in grid currents, while dynamically adjusting output through compensation devices to improve current waveforms.

The core of harmonic detection employs instantaneous reactive power algorithms, which decompose three-phase currents into active and reactive components through coordinate transformation (typically using Clarke/Park transformations). This method offers fast response characteristics and accurate harmonic extraction, particularly suitable for dynamically changing load conditions. Implementation typically involves calculating p-q instantaneous power components and applying low-pass filters to separate fundamental frequencies from harmonics.

Reactive compensation is commonly achieved through inverters or SVG (Static Var Generators). The compensation device generates counter-harmonic currents based on detection results, canceling distortion components in the grid while compensating reactive power to make grid connection point currents approximate sinusoidal waves. Control algorithms often utilize PI regulators or PR controllers to generate precise compensation references for power electronic switches.

Comparison of current waveforms before and after compensation clearly demonstrates: pre-compensation currents may exhibit significant distortion or phase displacement, while post-compensation waveforms become smoother and maintain phase synchronization with voltage. This technology not only improves power factor but also effectively suppresses harmonic interference in the grid, serving as a key technology in renewable energy grid integration applications.