An enhanced phase-locked loop for non-ideal grids combining linear active disturbance controller with moving average filter. (July 2023)

• Record Type: Journal Article
• Authors: Pan, Zhifeng; Wang, Xiaohong; Hoang, Thi Thu Giang; Tian, Lianfang
• Is Part Of: International journal of electrical power & energy systems. Volume 149(2023)
• Publication Date: 2023-07
• Subjects: Linear active disturbance rejection controller (LADRC) -- Moving average filter (MAF) -- Voltage unbalance -- Grid harmonic -- Direct current offset; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2023.109021
• Languages: English
• ISSNs: 0142-0615

Abstract

Abstract: Aiming at the accuracy deterioration of the synchronous reference frame phase-locked loop (SRF-PLL) caused by the non-ideal grid conditions and the limitation of phase-locked loop based on the linear active disturbance rejection controller (LADRC-PLL), this paper proposes an enhanced three-phase phase-locked loop combining the improved moving average filter and linear active disturbance rejection controller (IMAF-LADRC-PLL). First, a linear extended state observer (LESO) is presented to estimate all uncertainties and disturbances of SRF-PLL. On this basis, an improved moving average filter (IMAF) with phase-lead compensator is used to further enhance the harmonic suppression property. By combining the LESO and IMAF in a specific control structure, the proposed IMAF-LADRC-PLL has satisfactory steady-state accuracy without sacrificing the dynamic performance. To ensure the phase-locked accuracy against frequency fluctuation, a frequency-adaptive implementation is suggested. Furthermore, the parameter tuning and performance analysis of IMAF-LADRC-PLL are also presented in this paper. Experimental results show that the proposed IMAF-LADRC-PLL can achieve better dynamic performance on frequency step response and maintain the phase-locked accuracy in the presence of grid harmonics, voltage unbalances and direct current offsets, compared with the traditional LADRC-PLL or PID-type IMAF-PLL strategy. Highlights: The errors analysis of SRF-PLL in presence of non-ideal grid conditions are provided. A linear extended state observer (LESO) is presented to estimate all uncertainties. An improved MAF (IMAF) is used to further enhance the harmonic suppression property. The proposed PLL combines the LESO and IMAF to achieve the satisfactory performance. A frequency-adaptive implementation is introduced to ensure the accuracy of PLL.