Abstract
Phase-locked loop (PLL) is a fundamental and crucial component of a photovoltaic (PV) connected inverter, which plays a significant role in high-quality grid connection by fast and precise phase detection and lock. Several novel critical structure improvements and proportional-integral (PI) parameter optimization techniques of PLL were proposed to reduce shock current and promote the quality of grid connection at present. However, the present techniques ignored the differential element of PLL and did not acquire ideal results. Thus, this paper adopts Aquila optimizer algorithm to regulate the proportional-integral-differential (PID) parameters of PLL for smoothing power fluctuation and improving grid connection quality. Three regulation strategies (i.e., PLL regulation, global regulation, and step regulation) are carefully designed to systematically and comprehensively evaluate the performance of the proposed method based on a simulation model in MATLAB/Simulink, namely, “250-kW Grid-Connected PV Array”. Simulation results indicate that PLL regulation strategy can effectively decrease power fluctuation and overshoot with a short response time, low complexity, and time cost. Particularly, the Error(P) and the maximum deviation of output power under optimal parameters obtained by PLL strategy are decreased by 418 W and 12.5 kW compared with those under initial parameters, respectively.
Highlights
The rapid growth and development of the world economy and society are accompanied by the consumption and utilization of enormous non-renewable energy (Yang et al, 2018a; Zhang et al, 2021), especially fossil fuel, which leads to a great challenge for uninterrupted energy supply and environmental protection (Gan et al, 2019; Pabitra and Abhik, 2020)
Several structural improvement techniques of conventional phase-locked loop (PLL) have been suggested in the past few years
In the literature (Musengimana et al, 2021), a low-frequency damping strategy was presented to mitigate low-frequency oscillations related to PLL, which improved the performance of PV-connected inverter and outer loop controller
Summary
The rapid growth and development of the world economy and society are accompanied by the consumption and utilization of enormous non-renewable energy (Yang et al, 2018a; Zhang et al, 2021), especially fossil fuel, which leads to a great challenge for uninterrupted energy supply and environmental protection (Gan et al, 2019; Pabitra and Abhik, 2020). Phase lock technology is immensely applied to improve the performance of photovoltaic grid-connected inverters via fast and accurately extracting and tracking the phase angle information of grid voltage (Se-Kyo, 2000). Rodriguez et al (2007) designed a decoupled double synchronous reference frame phase-locked loop (PLL) to Optimal PID Tuning of PLL efficiently detect positive sequence voltage under unbalanced and distorted grid conditions. Kong et al (2020) proposed a novel self-adjusting double second-order generalized integrator PLL (SOGI-PLL) strategy with the ideal low-pass filter, which acquired desirable performance in the PV grid with high harmonic content. In the literature (Musengimana et al, 2021), a low-frequency damping strategy was presented to mitigate low-frequency oscillations related to PLL, which improved the performance of PV-connected inverter and outer loop controller
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