Adaptive Network Protection for Microgrids
Eng. Khaled Mostafa Sedik;
Abstract
Microgrids (MG) have been attracting greater attention due to their economic and environmental aspects. The continuous change in microgrid status from connected to islanded mode causes a change in the magnitude and direction of current flow during normal and faulty conditions. Hence, fixed protection relay settings will not be suitable for microgrid operation and may cause nuisance tripping or even no tripping in some other cases.
The literature includes different techniques to tackle this problem, among these is the adaptive network protection scheme, where the protection relay settings are continuously changed in accordance with the microgrid status (grid connected or islanded mode) and configuration (number and location of operating DGs). This technique ensures suitable relay setting, but requires a strong and reliable communication interface between the MG control center and all the protection relays to continuously update the settings according to the network configuration. This dependence on the communication interface strongly affects the system reliability.
This thesis proposes an enhanced adaptive protection scheme where all MG configurations are studied in normal operation and for different fault locations. Modern digital protection relays can adopt up to four groups of predefined settings. Hence, the calculated minimum and maximum short circuit currents seen by the relay for different configurations and different faulty buses are categorized into only 4 groups. The corresponding setting for these 4 groups is calculated and predefined for each relay and the communication system will only be responsible for defining the network configuration status.
The proposed adaptive network protection scheme is applied on IEEE 13 buses distribution system, to study the impact of distributed generation on the protection scheme and prove the proposed design scheme. The scheme takes into account typical overcurrent protection schemes, coordination and distributed generation impact on protection system. The results show the effectiveness of the proposed scheme and calculate the time difference in relay response for each of the fixed setting, the typical adaptive and the proposed enhanced grouping scenario.
Keywords: Adaptive protection, Microgrid (MG), Distributed generator (DG) and IEEE 13 nodes
The literature includes different techniques to tackle this problem, among these is the adaptive network protection scheme, where the protection relay settings are continuously changed in accordance with the microgrid status (grid connected or islanded mode) and configuration (number and location of operating DGs). This technique ensures suitable relay setting, but requires a strong and reliable communication interface between the MG control center and all the protection relays to continuously update the settings according to the network configuration. This dependence on the communication interface strongly affects the system reliability.
This thesis proposes an enhanced adaptive protection scheme where all MG configurations are studied in normal operation and for different fault locations. Modern digital protection relays can adopt up to four groups of predefined settings. Hence, the calculated minimum and maximum short circuit currents seen by the relay for different configurations and different faulty buses are categorized into only 4 groups. The corresponding setting for these 4 groups is calculated and predefined for each relay and the communication system will only be responsible for defining the network configuration status.
The proposed adaptive network protection scheme is applied on IEEE 13 buses distribution system, to study the impact of distributed generation on the protection scheme and prove the proposed design scheme. The scheme takes into account typical overcurrent protection schemes, coordination and distributed generation impact on protection system. The results show the effectiveness of the proposed scheme and calculate the time difference in relay response for each of the fixed setting, the typical adaptive and the proposed enhanced grouping scenario.
Keywords: Adaptive protection, Microgrid (MG), Distributed generator (DG) and IEEE 13 nodes
Other data
| Title | Adaptive Network Protection for Microgrids | Other Titles | الوقاية المتوائمة للشبكات الصغيرة | Authors | Eng. Khaled Mostafa Sedik | Issue Date | 2016 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| G13020.pdf | 466.64 kB | Adobe PDF | View/Open |
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