Intelligent distributed feeder automation system which supported by 5G connections is designed to realize intelligent judgment, analysis, fault location, fault isolation and non-fault area power supply restoration operations. As illustrated in the Figure A.4.4.3-1
, the distributed feeder automation system is mainly composed of a distribution master station, a distribution terminal, switch stations, and the communication system (UEs in the substations, 5G network, plus the data network). The distribution master station is mainly used for information gathering and human-computer interaction, and the distributed terminals are used for the collection of feeder status information and judgment, fault location, isolation, as well as power supply restoration based on this information. Distributed terminal actions are reported to the distribution master station. The 5G communication system enables communication among the distribution terminals. The distribution master station is usually connected to the 5G system via a data network, which is out of 3GPP scope.
The distribution master station manages multiple distributed terminals. Each distributed terminal is served by a 5G UE to exchange the collected data with other distributed terminals. From an application perspective, the communication between distributed terminals is peer-to-peer. The 5G communication service availability needs to be very high. Therefore, at least two communication links are usually deployed for hot standby or for transmitting data synchronously between two distributed terminals. The associated KPI is provided in Table A.4.4.3-1
Use cases #1:
Intelligent distributed feeder automation
High-speed current differential protection, which is required for sub-millisecond fault detection, is another typical use case of power distribution automation. The approach utilises differential current measurements to significantly reduce fault detection time. The protection relays exchange the current samples via the 5G system. Each relay then compares the sent and received samples to determine if a fault has occurred in a protected area. This is done in order to identify and isolate a fault in the grid. The sampling rate varies and is dependent on the algorithms designed by the manufacturers. A protection relay collects the current samples (with the typical message size of up to 245 bytes) at a frequency of 600 Hz, 1200 Hz, 1600 Hz, or 3000 Hz. The exchange of measurement samples is done in a strictly cyclic and deterministic manner. With the sampling rate of 600 Hz, the transfer interval is 1.7 ms and the required bandwidth 1.2 Mbit/s; for 1200 Hz, the transfer interval is 0.83 ms and the required bandwidth 2.4 Mbit/s. The maximum allowed end-to-end delay between two protection relays is between 5 ms and 10 ms, depending on the voltage (see IEC 61850-90-1 for more details ). For some legacy systems, the latency usually is set to 15 ms. The associated KPIs are provided in Table A.4.4.4-1
Use case #1:
High-speed current differential protection with a sampling rate of 1200 Hz for legacy systems.
Use case #2:
High-speed current differential protection with a sampling rate of 600 Hz for legacy systems.
Use case #3:
High-speed current differential protection with a sampling rate of 1200 Hz under voltage condition 1 (see IEC 61850-90-1 for more details).
Use case #4:
High-speed current differential protection with a sampling rate of 600 Hz under voltage condition 1 (see IEC 61850-90-1 for more details).
Use case #5:
High-speed current differential protection with a sampling rate of 1200 Hz under voltage condition 2 (see IEC 61850-90-1 for more details).
Use case #6:
High-speed current differential protection with a sampling rat