| Author: | Duan, Zhijun |
| Title: | Ancillary grid services from grid-following inverters during grid faults |
| Advisors: | Chan, Ka Wing (EEE) |
| Degree: | M.Sc. |
| Year: | 2024 |
| Department: | Department of Electrical and Electronic Engineering |
| Pages: | v, 119 pages : color illustrations |
| Language: | English |
| Abstract: | In response to global warming, environmental degradation, and the potential depletion of fossil fuel reserves, renewable energy power generation is increasingly being integrated into the power grid via power electronics converters. The interfaced power converter is popularly controlled by the grid-following control strategy and is therefore termed as the grid-following converter. This converter has helped the development of renewable energy power generation, yet it also brings new challenges that complicate management. Grid faults are very common in practical operations, and the grid-following converter needs to ride through these faults and actively provide various ancillary services according to grid codes to support the grid. Hence, based on a single converter and equivalent grid system, this dissertation studies the grid-following converter and examines how the converter facilitates various auxiliary grid services during both symmetrical and asymmetrical grid issues. The paper first introduces the fundamental architecture and parametric design of grid-following converters with analytical methodologies. Furthermore, the fundamental framework of low-voltage ride-through, prevalent globally, is examined. An optimised scheme is proposed based on power flow, considering grid impedance characteristics and short-circuit ratio. It can improve LVRT efficiency, maximize the current carrying capacity of the line, and increase the active power output and economic benefits of users. The utilisation of instantaneous power theory in addressing asymmetrical faults is examined. Corresponding to active and reactive power ripple and negative sequence current, a solution is summarized respectively, and the limitations of each solution are discussed. The current limiting method is used to solve the overcurrent problem that may occur in the solution Finally, novel concepts are suggested for further investigation, and a perspective on the future advancement of the field is provided. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 8481.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 7.9 MB | Adobe PDF | View/Open |
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