Abstract
It tends to cause system oscillation when the inverter with a phase-locked loop based on proportional integral controller (PI-PLL) is connected to the weak grid. To improve the oscillation suppression ability of the grid-connected inverter, a linear active disturbance rejection controller is applied to PLL (LADRC-PLL). Considering the influence of linear extended state observer, voltage outer-loop, current inner-loop and frequency coupling, the admittance model of the grid-connected inverter with LADRC-PLL is established. Based on the established admittance model and the generalized Nyquist criterion, the system stabilities of the grid-connected inverters with LADRC-PLL and PI-PLL are compared. The comparison results indicate that the grid-connected inverter with LADRC-PLL has better adaptability to the weak grid and shows a certain ability to suppress the sub- and super-synchronous oscillation. Then, the influence of the control parameters of LADRC-PLL on the system stability is studied. It is found that the system keeps stable when the control parameter of LADRC-PLL is changed in a relatively wide range, which indicates LADRC-PLL has good robustness. Furthermore, the dynamic performances of the grid-connected inverters with LADRC-PLL and PI-PLL are analyzed. It is revealed that the grid-connected inverter with LADRC-PLL has better dynamic performance. Finally, the correctness of the analysis is verified by experiments.
Original language | English |
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Journal | IEEE Transactions on Industrial Electronics |
Volume | 68 |
Issue number | 12 |
Pages (from-to) | 12272 - 12284 |
ISSN | 0278-0046 |
DOIs | |
Publication status | Published - Dec 2021 |
Keywords
- Admittance
- Admittance modeling
- Impedance
- Inverters
- LADRC
- Oscillators
- Phase locked loops
- Power system stability
- stability analysis
- Stability criteria
- sub-and super-synchronous oscillation