Abstract
Societies have become increasingly dependent on electricity. If a blackout occurs, the utilities must restore the electricity system back to normal operation as soon as possible. Therefore, fast and robust system restoration is important.
This thesis studies the technical uncertainties related to electrical phenomena and protection and automation systems during transmission network restoration. This thesis focuses on a system level blackout. In this situation, the restoration is performed using a bottom-up approach. Consequently, the network being restored is extremely weak and prone to issues seldom encountered during normal operation. As the thesis shows, the uncertainties may delay or even prevent restoration using specific restoration paths. Therefore, the utilities must manage and mitigate the uncertainties in restoration planning and when restoring the system from a blackout. This thesis proposes a restoration planning process to identify and manage the uncertainties. In addition, this thesis presents measures to manage four unwanted electrical phenomena during restoration: black-start generator self-excitation, harmonic resonance during transformer energization, parallel line resonance and ferroresonance and subsequent sustained parallel resonance.
This thesis shows that simulations alone are not sufficient for the identification of the uncertainties related to system restoration. Therefore, restoration field-tests are a mandatory part of the restoration planning. However, testing only the black- start generator is not sufficient. In addition, the restoration field-tests must always include the restoration of the initial transmission network which allows the connection the black-start generator with consumption and other generation.
This thesis shows that simulation models tuned for normal system operation are not suitable for restoration studies since the dominant system dynamics during restoration are significantly different than during normal operation. Thus, sufficient measurements during field-tests and actual restoration actions are required to capture system dynamics and calibrate simulation models for restoration studies.
Restoration procedures may be unconventional and significantly different than normal system operation. Therefore, the restoration procedures must be properly planned, validated with field-tests and trained regularly for the operational personnel.
This thesis studies the technical uncertainties related to electrical phenomena and protection and automation systems during transmission network restoration. This thesis focuses on a system level blackout. In this situation, the restoration is performed using a bottom-up approach. Consequently, the network being restored is extremely weak and prone to issues seldom encountered during normal operation. As the thesis shows, the uncertainties may delay or even prevent restoration using specific restoration paths. Therefore, the utilities must manage and mitigate the uncertainties in restoration planning and when restoring the system from a blackout. This thesis proposes a restoration planning process to identify and manage the uncertainties. In addition, this thesis presents measures to manage four unwanted electrical phenomena during restoration: black-start generator self-excitation, harmonic resonance during transformer energization, parallel line resonance and ferroresonance and subsequent sustained parallel resonance.
This thesis shows that simulations alone are not sufficient for the identification of the uncertainties related to system restoration. Therefore, restoration field-tests are a mandatory part of the restoration planning. However, testing only the black- start generator is not sufficient. In addition, the restoration field-tests must always include the restoration of the initial transmission network which allows the connection the black-start generator with consumption and other generation.
This thesis shows that simulation models tuned for normal system operation are not suitable for restoration studies since the dominant system dynamics during restoration are significantly different than during normal operation. Thus, sufficient measurements during field-tests and actual restoration actions are required to capture system dynamics and calibrate simulation models for restoration studies.
Restoration procedures may be unconventional and significantly different than normal system operation. Therefore, the restoration procedures must be properly planned, validated with field-tests and trained regularly for the operational personnel.
| Original language | English |
|---|---|
| Place of Publication | Tampere |
| Publisher | Tampere University |
| ISBN (Electronic) | 978-952-03-2507-7 |
| ISBN (Print) | 978-952-03-2506-0 |
| Publication status | Published - 2022 |
| Publication type | G5 Doctoral dissertation (articles) |
Publication series
| Name | Tampere University Dissertations - Tampereen yliopiston väitöskirjat |
|---|---|
| Volume | 643 |
| ISSN (Print) | 2489-9860 |
| ISSN (Electronic) | 2490-0028 |