Protective Relay Sampling Synchronization via Phase Difference Feedback
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Solution Overview
Problem
Current protective relaying devices face challenges in synchronizing sampling timings accurately due to variations in transmission delay times between up-transmission and down-transmission, leading to differential current errors and reduced sensitivity.
Innovation Solution
A protective relaying device with measuring, phase difference calculating, and setting means to determine and adjust the target value for sampling synchronization control, ensuring accurate synchronization by measuring transmission times and phase differences to compensate for transmission delay differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sampling synchronization control is performed assuming equal transmission delay times for up-transmission and down-transmission, then the control system remains simple, but sampling synchronization errors occur due to actual transmission delay variations
Solution Approach 1:
The patent implements feedback by measuring the actual transmission delay times for both up-transmission (Td1) and down-transmission (Td2), calculating the phase difference based on these measurements, and using this feedback information to dynamically adjust the target value of sampling synchronization control. This closed-loop feedback mechanism resolves the contradiction by maintaining synchronization accuracy without requiring overly complex predetermined compensation schemes.
Solution Approach 2:
The patent changes the parameter being controlled from a fixed target value (TF-TM=0) to a dynamically adjusted target value based on measured transmission delays and calculated phase differences. By modifying the target value according to actual system conditions, the patent achieves accurate synchronization while keeping the control structure relatively simple.
2Ease of manufacture
If the target value of sampling synchronization control is set to 0 (TF-TM=0), then the control method remains simple and consistent with prior art, but sampling synchronization errors of about 6% occur due to transmission delay differences
Solution Approach 1:
The patent performs preliminary measurement of transmission delay times (Td1 and Td2) and calculation of phase differences before setting the target value for sampling synchronization control. This preliminary action allows the system to establish an accurate target value in advance, avoiding synchronization errors while maintaining control simplicity.
3Device complexity
If transmission delay time differences between up-transmission and down-transmission are not compensated, then the system operates with minimal complexity, but differential current errors increase and relaying sensitivity decreases
Solution Approach 1:
The patent changes the approach from directly compensating transmission delay differences to adjusting the target value of sampling synchronization control based on measured delays and calculated phase differences. This parameter change achieves differential current measurement accuracy without requiring complex real-time compensation mechanisms.
Data Source
AI summary
In one embodiment, a protective relay apparatus is provided with: a phase difference calculating means (2) for calculating the phase difference between a phase the result of shifting the phase of a first current data 180 degrees, and a phase of a second current data; a setting means (3) for calculating and setting, on the basis of the phase difference, a target value for getting rid of sampling synchronization errors generated by the difference in transmission delay time between the upward and downward directions; and a sampling synchronization controlling means (4) for conducting a sampling synchronization control so that the difference between a period of time (TM), which starts from a particular position on the transmission format of a first protective relay apparatus, and ends when the first protective relay apparatus receives data of a particular position on the transmission format of a second protective relay apparatus, and a period of time (TF), which starts from the particular position on the transmission format of the second protective relay apparatus, and ends when the second protective relay apparatus receives data of the particular position on the transmission format of the first protective relay apparatus, will become the target value.