Differential Protection Threshold Adjustment for Network Jitter
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Solution Overview
Problem
Differential protection systems in electrical power supply networks face issues with false tripping due to uncertainties in temporal alignment of current measurements when transmitted via non-deterministic communication networks, leading to incorrect assignment of current values and potential faults.
Innovation Solution
The method involves transmitting current measurements as high-priority messages through communication networks with nodes prioritizing high-priority messages over low-priority ones, determining a jitter parameter for maximum possible transmission time, and adjusting the threshold value based on this parameter to account for transmission uncertainties, thereby adapting the sensitivity of error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If current measurement values are transmitted via non-deterministic communication networks, then cost-effective communication infrastructure is achieved, but temporal alignment uncertainty causes false tripping
Solution Approach 1:
The patent adjusts the threshold value parameter dynamically based on the jitter parameter to compensate for transmission time uncertainties. By changing the threshold parameter according to network conditions, the system maintains reliable fault detection while using cost-effective non-deterministic communication networks.
Solution Approach 2:
The system determines the jitter parameter in advance and uses it to pre-calculate the appropriate threshold value before differential protection assessment. This preliminary action ensures that the threshold is already optimized for the current network conditions, preventing false tripping while maintaining cost-effectiveness.
2Reliability
If threshold value is increased to reduce false tripping, then reliability improves, but measurement precision deteriorates
Solution Approach 1:
The threshold value is made dynamic rather than static, adjusting automatically based on the jitter parameter that reflects current network conditions. This dynamic adaptation allows the system to maintain high measurement precision when network conditions are good while increasing reliability when jitter is present, avoiding the need for a permanently conservative high threshold.
Solution Approach 2:
The system uses the jitter parameter as feedback from the communication network to continuously adjust the threshold value. This feedback mechanism ensures that the threshold always reflects current network conditions, maintaining both reliability and measurement precision without manual intervention.
3Measurement precision
If synchronization is improved to reduce temporal alignment uncertainty, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent introduces the jitter parameter as an intermediary that characterizes temporal alignment uncertainty without requiring complex synchronization mechanisms. Instead of directly synchronizing clocks with high precision, the system uses the jitter parameter to indirectly account for timing uncertainties, simplifying the overall system architecture.
Solution Approach 2:
The patent replaces complex mechanical or hardware-based synchronization systems with a software-based approach using the jitter parameter. By substituting physical synchronization mechanisms with a parameter-based computational approach, the system achieves temporal alignment precision without increasing device complexity.
Data Source
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AI summary
The invention relates to a differential protection method for generating a fault signal, which indicates a fault with regard to a primary component (11) of an electrical power supply network, wherein respective current measurement values are measured at at least two different measurement points (11a-b) of the primary component (11) of the electrical power supply network by means of measuring devices, the current measurement values are transmitted to a differential protection device, which calculates a differential current value by means of associated current measurement values of all measuring devices by addition in which correct signs are used, and the fault signal is generated by means of the differential protection device if the differential current value exceeds a specified threshold value. In order to specify a possibility by means of which a differential protection method can be performed as reliably as possible even in the case of transmission of the current measurement values by means of a non-deterministic communication network, said possibility being as economical as possible, the current measurement value of at least one measuring device according to the invention is transmitted to the differential protection device by means a communication network (16), wherein the communication network (16) comprises network nodes (40a-f), which are designed to send messages of high priority preferentially with respect to messages of low priority, and wherein the current measurement value is transmitted as a message of high priority, a jitter characteristic value is determined, which indicates a maximum possible transmission time of the message containing the current measurement value, and the value of the threshold value is defined in dependence on the jitter characteristic value. The invention further relates to a correspondingly designed differential protection device.