Transformer PLC Auto-Squelch Using RSSI for Fault Isolation
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Solution Overview
Problem
Existing fault isolation and protection schemes in power distribution networks using powerline communications (PLC) face challenges due to signal attenuation across transformers, necessitating fixed squelch levels that cannot be adjusted in the field, leading to inefficient communication and potential misinterpretation of PLC signals.
Innovation Solution
A method to determine a unique squelch level for each transformer based on network-specific factors like distance and attenuation, using a ping test to measure RSSI and set a predetermined reduction value for each transformer, ensuring effective communication by adjusting the squelch level dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed squelch level is used for PLC communication in power distribution networks, then device complexity is reduced and ease of manufacture is improved, but communication reliability deteriorates due to signal attenuation variations across different transformers and network conditions
Solution Approach 1:
The system performs preliminary actions by automatically determining and storing the squelch level for each transformer during initial network operation. The control unit measures signal strength from PLC messages received through open switching devices and configures the appropriate squelch level before fault isolation operations are needed, eliminating the need for manual field programming and ensuring reliable communication under specific network conditions
Solution Approach 2:
The control unit serves itself by automatically determining its own squelch level without requiring external programming or manual configuration. The system measures the signal strength of PLC messages received through open switching devices and autonomously configures the squelch level parameter, making the device self-configuring and eliminating dependency on field technicians for programming
2Reliability
If the squelch level is set too low, then PLC signals can be received from distant transformers, but harmful factors increase due to processing of invalid signals from downstream transformers through open switching devices
Solution Approach 1:
The system changes the squelch level parameter dynamically based on network conditions and transformer location. By measuring the signal strength of PLC messages received through open switching devices and configuring an appropriate squelch level for each transformer, the system optimizes the parameter to distinguish valid upstream signals from invalid downstream signals, preventing false signal processing while maintaining reliable communication
Data Source
AI summary
A system and method for determining a squelch level for each transformer in a series of transformers connected to a power line that communicate with each other through PLC. The method includes selectively transmitting a PLC test message by each transformer on the power line both upstream and downstream of the transmitting transformer to determine that the transmitting transformer can communicate with other transformers; responding to the PLC test message that is received by each transformer to identify the transformers that can communicate with the transmitting transformer; measuring the RSSI of the PLC messages that each transformer receives; recording the strongest RSSI in each transformer of the PLC messages that are received by the transformer; and setting the squelch level for each transformer as a predetermined reduction of the recorded RSSI in each transformer.