HVDC Line Protection for High-Resistance Fault Detection
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Solution Overview
Problem
High-resistance faults in HVDC transmission lines pose a challenge for traveling wave protection systems, leading to reduced sensitivity and increased risk of action rejection due to minimal changes in voltage and current amplitudes, which complicates fault identification.
Innovation Solution
A method and system that utilize single-ended quantity protection by compensating line-mode fault voltage based on DC line and system parameters, improving sensitivity by eliminating the influence of fault resistance, and determining fault polarity using zero-mode fault voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traveling wave protection is used for HVDC transmission line protection, then fast fault detection speed is achieved, but protection sensitivity is insufficient when high-resistance fault occurs
Solution Approach 1:
The patent transforms the protection criterion from using voltage and current amplitudes to using their time derivatives (rates of change). This parameter transformation makes the protection insensitive to fault resistance magnitude, as the derivative operation amplifies the transient fault signal while suppressing the steady-state influence of resistance. The new criterion uses du/dt and di/dt instead of u and i, fundamentally changing the sensitivity characteristics.
Solution Approach 2:
The patent replaces the traditional amplitude-based detection mechanism with a derivative-based detection mechanism. By substituting the measurement of voltage and current magnitudes with the measurement of their rates of change, the system achieves both fast response (inheriting the traveling wave advantage) and high sensitivity to high-resistance faults (through the derivative amplification effect).
2Device complexity
If voltage amplitudes and current amplitudes are used as characteristic quantities, then the protection criterion is simple, but the change of total characteristic quantity is slight when fault resistance increases
Solution Approach 1:
The patent changes the measurement parameters from voltage and current amplitudes to their time derivatives. This parameter transformation fundamentally alters the response characteristics: while amplitude-based measurement shows slight changes with increasing fault resistance, the derivative-based measurement maintains significant response even for high-resistance faults, thereby improving measurement precision without substantially increasing system complexity.
Data Source
AI summary
Provided are a method and system for protecting the HVDC line, device, and storage medium. The method for protecting the HVDC line includes that: a DC line parameter and a DC system operation parameter are acquired, and a DC line protection installation position operation parameter is sampled; a line-mode fault voltage of a sampling point, a zero-mode fault voltage of the sampling point, a line-mode fault current of the sampling point, and a continuous rate of change of the line-mode fault current are calculated; in response to starting the line protection, the line-mode fault voltage is compensated based on the DC line parameter, the DC system operation parameter, and a first peak value of the line-mode fault voltage; and in response to determining that the HVDC line is faulty, a line fault polarity is determined based on the zero-mode fault voltage.