Feeder Protection Redundancy via Cross-Feeder Monitoring
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Solution Overview
Problem
Existing feeder protection systems in electrical power networks are vulnerable to malfunctions of intelligent electronic devices and measurement instruments, leading to power outages, as they lack redundancy and reliability, especially when a single device failure occurs.
Innovation Solution
Implementing a system with three redundant protection functions that operate independently at the feeder and nodal point levels, using measurement data from other feeders to monitor and protect a specific feeder, ensuring continuous power supply even if primary measurement information is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single intelligent electronic device is used for feeder protection, then the device complexity is reduced, but the reliability of protection is insufficient
Solution Approach 1:
The protection system is segmented into multiple independent protection functions: first protection function at feeder level, second protection function at nodal point level using measurements from other feeders, and third protection function as backup. This segmentation allows each function to operate independently, so that failure of one does not compromise the entire protection system.
Solution Approach 2:
The system uses measurements from other feeders connected to the same nodal point as an intermediary to monitor the power system related condition of a specific feeder. When measurement data from the specific feeder is unavailable, the central intelligent electronic device can still execute protection functions using data from other feeders, maintaining protection reliability without requiring direct measurement from the protected feeder.
2Reliability
If a spare intelligent electronic device is provided for critical feeders, then the outage time is reduced, but the system costs increase
Solution Approach 1:
The central intelligent electronic device performs multiple functions: it executes the second protection function for monitoring specific feeders and the third protection function using measurements from other feeders. This multi-functionality eliminates the need for dedicated spare devices, as the same device can provide backup protection capabilities for multiple feeders.
Solution Approach 2:
The system merges the backup protection capability into the existing central intelligent electronic device rather than adding separate spare devices. By combining the second and third protection functions in a single device, the system achieves redundancy without increasing the number of physical devices.
3Reliability
If measurement data from a specific feeder is required for protection, then the measurement precision is high, but the system becomes vulnerable to measurement instrument failures
Solution Approach 1:
The system prepares alternative measurement sources in advance by establishing the capability to use measurements from other feeders connected to the same nodal point. When measurement data from the specific feeder becomes unavailable, this pre-established alternative pathway allows the protection function to continue operating without interruption.
Solution Approach 2:
The system creates a virtual copy of the measurement data by using measurements from other feeders to represent the power system related condition of the specific feeder. This copying approach allows the protection function to operate with substitute data when the original measurement is unavailable, maintaining system reliability.
Data Source
AI summary
A system and method for feeder protection in an electrical power network nodal point including at least three feeders. In the system and the method it is executed in an intelligent electronic device reserved for the feeder, on the basis of the at least one measured electrical quantity actual in the respective feeder, at least one first protection function monitoring a power system related condition of the respective feeder, as well as in a central intelligent electronic device, for at least one feeder, at least one second protection function monitoring the same power system related condition of the feeder. Furthermore the central intelligent electronic device is configured to further execute for the at least one feeder, on the basis of the at least one measured electrical quantity actual in the other feeders connected to the same nodal point, at least one third protection function monitoring the same power system related condition of the feeder.