System theoretical analyses of voltage stability in power electronics-dominated hybrid power systems
| dc.contributor.advisor | Rehtanz, Christian | |
| dc.contributor.author | Liemann, Sebastian | |
| dc.contributor.referee | Becker, Christian | |
| dc.date.accepted | 2024-11-19 | |
| dc.date.accessioned | 2025-01-31T12:38:01Z | |
| dc.date.available | 2025-01-31T12:38:01Z | |
| dc.date.issued | 2024 | |
| dc.description.abstract | The massive integration of power electronic de-vices at the load and generation side is changing the dynamics and stability of power systems. In particular, power electronic loads can threaten voltage stability in the event of major disturbances, such as short circuits, due to their low voltage sensitivity. In addition, the ancillary services of decommissioned conventional power plants have to be taken over by grid-forming converters. Since power electronic converters and loads can discretely change their dynamics during disturbances, e.g. by current limitation or disconnection with zero power consumption, additional challenges for voltage stability arise. Therefore, in this thesis, hybrid system theory is used as a modelling basis to explicitly analyse the complex interactions between continuous and discrete dynamics in such events. It is examined how the theory of hybrid systems can extend the system theory of voltage stability and how it can support its assessment in the short and long term. Furthermore, since there is only a small overlap between conventional voltage stability dynamics and power electronics dynamics, it is not clear whether phasor or electromagnetic transient models should be used. Therefore, grid-forming converters and power electronic loads are modelled for both types. The simulation results show that phasor models may still be suitable for grid-forming converters, while electromagnetic transient models are needed for power electronic loads. In addition, the results demonstrate that the current limitation of grid-forming converters can lead to voltage instability in the short and long term. However, by applying stability-enhancing control methods, the instability induced by the converter can be avoided. The disconnection of power electronic loads during short circuits can initially stabilise the system due to the reduced power consumption. Yet, their potential fast power recovery during the fault can lead to instability or delayed voltage recovery afterwards. The combined simulation of grid-forming converters and power electronic loads show that the simultaneous occurrence of current limitation and fast power recovery can be a serious threat to short- and long-term voltage stability. | en |
| dc.identifier.uri | http://hdl.handle.net/2003/43395 | |
| dc.identifier.uri | http://dx.doi.org/10.17877/DE290R-25227 | |
| dc.language.iso | en | |
| dc.subject | Voltage stability | en |
| dc.subject | Grid-forming | en |
| dc.subject | Power electronic load | en |
| dc.subject | Hybrid system | en |
| dc.subject | Power system | en |
| dc.subject.ddc | 620 | |
| dc.title | System theoretical analyses of voltage stability in power electronics-dominated hybrid power systems | en |
| dc.type | Text | |
| dc.type.publicationtype | PhDThesis | |
| dcterms.accessRights | open access | |
| eldorado.secondarypublication | false |