HVDC Transmission Monitoring via Multi-Interval Current Thresholds
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Solution Overview
Problem
Conventional HVDC converter stations are unable to quickly detect and respond to DC faults, leading to prolonged interruptions and increased stress on transmission components, which can result in damage and reduced component lifespan.
Innovation Solution
A method for monitoring HVDC transmission lines that sets current strength and change threshold values for each pole, allowing for rapid detection of faults by comparing actual current intensity and changes with predefined thresholds, and regulating currents to zero to mitigate fault currents, with optional discharge of charged poles in symmetrical monopolar systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional threshold-based fault detection is used, then the system structure remains simple, but the fault detection speed is insufficient and causes prolonged interruptions
Solution Approach 1:
The monitoring system is segmented into multiple independent evaluation units, each responsible for a specific time interval. This allows parallel processing of current measurements across different intervals, significantly improving fault detection speed without requiring a single complex centralized system.
Solution Approach 2:
Threshold values for current magnitude and rate of change are pre-calculated and stored for multiple time intervals before operation. This preliminary preparation eliminates the need for complex real-time calculations during fault detection, enabling rapid comparison and immediate fault identification when abnormalities occur.
2Reliability
If DC faults are not quickly detected, then the converter stations remain connected longer, but this causes increased voltage stress and damage to transmission components
Solution Approach 1:
The system dynamically adapts its monitoring approach by evaluating current measurements across multiple time intervals with different threshold criteria. This dynamic evaluation allows the system to detect both sudden faults (using shorter intervals) and developing faults (using longer intervals), enabling rapid response that protects components while minimizing unnecessary interruptions.
Solution Approach 2:
The monitoring system continuously compares actual current measurements against pre-calculated threshold values and immediately triggers fault detection when thresholds are exceeded. This real-time feedback mechanism ensures that faults are detected at the earliest possible moment, allowing rapid disconnection that prevents voltage stress damage while minimizing interruption duration through quick reinstatement capability.
3Productivity
If conventional half-bridge converter technology is used, then the converter design is simpler, but the converter stations must be blocked and disconnected during DC faults causing prolonged interruptions
Solution Approach 1:
The system pre-calculates and stores threshold values for multiple time intervals and prepares rapid response protocols before faults occur. This preliminary preparation enables the converter station to maintain operation during certain fault conditions by quickly identifying and isolating only the affected components, rather than blocking the entire station, thus maintaining power transmission continuity.
Solution Approach 2:
The converter station is divided into independently monitorable and controllable segments corresponding to different time interval evaluations. This segmentation allows selective disconnection of only the faulty segment while maintaining operation of healthy segments, preserving productivity without requiring complete station shutdown that would result from conventional unified protection schemes.
Data Source
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AI summary
The invention relates to a method for monitoring a high-voltage DC transmission. In the method the following are predefined: an amperage threshold value (LI) for an amperage (I1, I2) of the high-voltage DC transmission, at least one interval length (Τ1, T2) for time intervals and, for each predefined interval length (Τ1, T2), a change threshold value (L2, L3) for a change in the amperage (I1, I2) averaged over time intervals of the interval length (Τ1, T2). The amperage (I1, I2) for each terminal (7, 8) of the high-voltage DC transmission is determined, and a change in the amperage (I1, I2) averaged over time intervals of the interval length (Τ1, T2)) is determined for each predefined interval length (Τ1, T2). A DC error is determined if the magnitude of the amperage (I1, I2) of at least one terminal (7, 8) is greater than the amperage threshold value (LI) or if, for an interval length (Ti, T2), the magnitude of the averaged change in the amperage (I1, I2) of at least one terminal (7, 8) is greater than the change threshold value (L2, L3) predefined for the interval length (Ti, T2).