A PRC-PI APF control method for improving power quality and harmonic suppression in substations
Year: 2026
Type: article
Abstract: Introduction Nonlinear loads in substations cause current distortion, increased harmonics, and reactive power, leading to power quality degradation and energy inefficiency. Traditional PI control lacks steady-state accuracy for AC signals, while conventional repetitive control (RC) suffers from slow transient response due to its inherent one-cycle delay. Methods This paper proposes a dual-loop proportional repetitive control-proportional integral (PRC-PI) strategy. An improved PRC with a proportional bypass term ( k prc ) is used in the outer loop to ensure multi-harmonic accuracy and improve transient recovery, while a high-bandwidth PI inner loop provides rapid current regulation. A decoupled double synchronous reference frame phase-locked loop (DDSRF-PLL) is also integrated to enhance phase tracking under unbalanced grid conditions. Results Simulation results show that the PRC-PI strategy reduces grid current Total Harmonic Distortion (THD) to 2.16%, significantly lower than traditional PI (8.54%) or RC-PI (3.80%) schemes. Experimental verification on an APF prototype confirms that Phase A grid current THD drops from 28.83% to 4.02%, and the system recovers to steady state within approximately one fundamental cycle (20ms) during load changes. Discussion The "precise outer loop and fast inner loop" structure effectively balances steady-state compensation accuracy with dynamic response speed. By significantly suppressing low-order harmonics and improving power quality, this strategy enhances the operational safety and reliability of substation equipment.
Source: Frontiers in Energy Research
Language: English
Topic: Power Quality and Harmonics
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,077
OpenAlex ID: W7124840384