Differential Protection Data Alignment After Time Sync Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Differential protection in power transmission systems faces challenges in maintaining correct time synchronization between differential protectors, leading to delays and uncertainties in current data alignment, especially when using merging units and process buses, which can result in incorrect protection operations.
Innovation Solution
A data alignment method that calculates and compensates for transmission delays between differential protectors, allowing for accurate alignment of current data even when time synchronization is lost, by determining a third time node based on calculated values and stored time calculation deviations, ensuring correct differential protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If current data is transmitted through merging unit and process bus, then automation system functionality is improved, but transmission delay and time synchronization uncertainty increase
Solution Approach 1:
The patent performs preliminary calculation of transmission delays during normal time-synchronized operation, storing these delay values for later use. When time synchronization is lost, these pre-calculated delay values are used to compensate for the unknown delays, enabling accurate data alignment without requiring real-time delay measurement.
Solution Approach 2:
The patent creates a virtual time reference by calculating equivalent time nodes based on stored delay characteristics. Instead of relying on actual real-time synchronization signals, the system copies the timing relationship using calculated values that represent the expected delay behavior, allowing differential protection to proceed even without active time synchronization.
2Measurement precision
If time synchronization is maintained between differential protectors, then data alignment accuracy is improved, but system complexity and synchronization maintenance requirements increase
Solution Approach 1:
The patent extracts the time synchronization requirement from the differential protection system by calculating and storing delay characteristics during synchronized operation. This allows the system to operate independently of active time synchronization while maintaining alignment accuracy, effectively removing the synchronization dependency while preserving its benefits.
3Measurement precision
If differential protector waits for time synchronization confirmation, then data alignment accuracy is improved, but response time for protection operations increases
Solution Approach 1:
The system performs preliminary calculations of transmission delays and stores these characteristics in advance. When protection operation is needed, even without time synchronization confirmation, the system can immediately use these pre-calculated values to align data accurately, eliminating the waiting time while maintaining alignment precision.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The embodiments of the present disclosure provide a data alignment method, a differential protector, and a differential protection system. The data alignment method comprises: obtaining, at a first time node, first sampled current data from a first sampling device; receiving, at a first moment , a second message from a second differential protector, the second message comprising second sampled current data and its sampling time stamp, first time information of the second differential protector related to a difference in time of reception from receipt of the first message to a second time node, and second time information of the second differential protector related to a second transmission processing delay from the second time node to transmission of the second message, the second time node being a time point when a second sampling device obtains the second sampled current data; when the time synchronization is maintained, calculating and storing a time calculation deviation between a third time node and a first calculated value of the second time node; when the time synchronization is lost, determining the third time node according to the stored time calculation deviation.