| Author: | Zhou, Yuqi |
| Title: | Transient stability of a power system with hybrid grid-forming controls under grid faults |
| Advisors: | Chan, Ka Wing (EEE) |
| Degree: | M.Sc. |
| Year: | 2024 |
| Department: | Department of Electrical and Electronic Engineering |
| Pages: | vii, 61 pages : color illustrations |
| Language: | English |
| Abstract: | With further development of renewable energy sources, grid-forming converters can play a significant role in the power system. In the near future, the system will inevitably contain various grid-forming converters and the conventional synchronous generator, which is also a type of grid-forming control. Thus, a new power system will be formed featuring hybrid grid-forming power generation units. Under this premise, current limiting strategies are mandatory for grid-forming converters, and therefore, transient stability of the hybrid electric power system under grid faults would become an issue worth of intensive research and discussions. In most studies, current limiting strategies are investigated in grid-forming converters instead of in a hybrid electric power system. Similarly, research about transient stability usually focuses on converters in the islanded mode or converters connected to an equivalent power grid. In this dissertation, the hybrid electric power system with diverse grid-forming power generation units is the focus of this study. Therefore, in Simulink, an IEEE-9 bus system is first developed, which consists of 1 synchronous generator and 2 grid-forming converters. The converters are based on droop-control and VSG control, while the synchronous generator is powered by a hydraulic prime mover. In addition, the dual-loop voltage and current control scheme is adopted to regulate tightly the voltage and current of the grid-forming converters. The main contribution of this study can be summarized as follows: • comparisons between different current limiting strategies under three-phase short-current faults in a hybrid electric power system. • Two current limiting methods are considered in this dissertation: magnitude current limiter and virtual impedance. They are evaluated by transient current limiting capability and the recovery speed after grid faults. • Transient stabilities under different current limiting methods are visualized by virtual power angle curves, and some unsolved issues about transient stability are also discussed. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 8485.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 2.86 MB | Adobe PDF | View/Open |
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