| 1. |
- Chen, Feifan, et al.
(författare)
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Dynamics Enhancement for Power Synchronization Control with Asymmetric AC Voltage Controller in Strong Grids
- 2023
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Ingår i: 2023 IEEE Conference on Control Technology and Applications, CCTA 2023. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1066-1070
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Konferensbidrag (refereegranskat)abstract
- Power synchronization control (PSC) is designed for weak grid connections originally and its performance is weakened when connected to a strong grid. In this paper, an asymmetric AC voltage controller (AVC) is proposed to improve the performance of PSC in strong grids. The improvement is achieved by adding a coupling from d-axis to q-axis to the voltage control part. The effect of this d-to-q coupling is explained by small signal modeling. It is found that the asymmetric AVC gives an effective improvement in damping the low-frequency oscillation and stability robustness against the grid strengths. Theoretical analysis and experiments verify the effectiveness of the proposed asymmetric AVC.
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| 2. |
- Chen, Feifan, et al.
(författare)
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Enhanced Q-Axis Voltage-Integral Damping Control for Fast PLL-Synchronized Inverters in Weak Grids
- 2024
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Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 39:1, s. 424-435
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Tidskriftsartikel (refereegranskat)abstract
- The phase-locked loop (PLL) is a commonly used synchronization control method for grid-tied inverters. The PLL-synchronized inverters tend to have poor stability robustness with weak grid interconnections, especially when the PLL is designed with a high control bandwidth. To tackle this challenge, this article proposes an enhanced q-axis voltage-integral damping control, which not only stabilizes PLL-synchronized inverters in weak grids but also lifts the restriction on PLL bandwidth. This superior feature enables inverters to operate stably in ultraweak grids and with a superior transient response. The experimental tests confirm the performance of the method with 400-Hz PLL bandwidth under a short-circuit ratio of 1.28 of the grids.
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| 3. |
- Chen, Feifan, et al.
(författare)
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Pitfalls of Using Passivity Index to Guide Grid-connected Inverter Control Design in Low-frequency Region
- 2023
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Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 758-764
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Konferensbidrag (refereegranskat)abstract
- The main purpose of this article is to elaborate on the pitfalls of using the frequency-domain passivity theories in grid-inverter interactions within the low-frequency range. It mainly covers the relationship between the passivity index and stability, considerations for control design guided by optimizing the passivity index, and issues with a negative infinite index. It is advised to exercise caution when applying passivity theory in the low-frequency range. These conclusions have been substantiated through numerical and experimental studies.
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| 4. |
- Pirsto, Ville, et al.
(författare)
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Intersample Modeling of the Converter Output Admittance
- 2021
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Ingår i: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 68:11, s. 11348-11358
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Tidskriftsartikel (refereegranskat)abstract
- The stability of the converter-grid interconnection can be studied by analyzing the product of the converter output admittance and the grid impedance. For reliable stability analysis, it has been of interest to obtain accurate converter output admittance models for a wide range of frequencies, ideally also around and above the Nyquist frequency of the converter system. This article presents a modeling method for the output admittance of power converters defined in the Laplace domain that takes into account the discrete nature of the control system. The modeling method is based on analyzing the intersample behavior of sampled-data systems, a class of systems that includes the modern digitally controlled power converters. The proposed method is compared to conventional admittance modeling methods, and its accuracy is validated by means of simulations and experiments.
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