Line fault detection method, system, device, and computer-readable storage medium

A line fault detection method, comprising:

• injecting a pulse signal into a grounding electrode line and acquiring fault voltage traveling wave data responding to a fault point in the grounding electrode line based on a measuring spot;
• based on the fault voltage traveling wave data and a preset step size, determining a voltage forward traveling wave sequence and a voltage reverse traveling wave sequence for the grounding electrode line;
• based on corresponding energy superposition expressions of the voltage forward traveling wave sequence and the voltage reverse traveling wave sequence, determining an integral value sequence of a traveling wave product within a preset time period;
• and
• based on a maximum mutation point in the integral value sequence, determining a fault distance;
• wherein steps of determining the voltage forward traveling wave sequence and the voltage reverse traveling wave sequence for the grounding electrode line based on the fault voltage traveling wave data and the preset step size comprises:
• performing a line mode transformation on the fault voltage traveling wave data to obtain line mode voltage traveling wave components of the grounding electrode line;
• based on the preset step size and the line mode voltage traveling wave components, determining voltage and current distribution along the grounding electrode line at any given moment;
• and
• based on the voltage and current distribution as well as line mode wave impedance of the grounding electrode line, determining the voltage forward traveling wave sequence and the voltage reverse traveling wave sequence;
• wherein steps of determining the integral value sequence of the traveling wave product within the preset time period based on the corresponding energy superposition expressions of the voltage forward traveling wave sequence and the voltage reverse traveling wave sequence comprise:
• obtaining a first numerical change gradient corresponding to the voltage forward traveling wave sequence and a second numerical change gradient corresponding to the voltage reverse traveling wave sequence;
• based on the first numerical change gradient, the second numerical change gradient, a traveling wave velocity, a line length of the grounding electrode line, a sampling frequency, and the preset step size, determining a forward voltage traveling wave energy superposition expression and a reverse voltage traveling wave energy superposition expression, respectively;
• multiplying the forward voltage traveling wave energy superposition expression and the reverse voltage traveling wave energy superposition expression to determine an integral value for the preset time period within the grounding electrode line;
• and
• mapping integral values to a distance dimension to obtain the integral value sequence;
• before steps of obtaining the first numerical change gradient corresponding to the voltage forward traveling wave sequence and the second numerical change gradient corresponding to the voltage reverse traveling wave sequence, the line fault detection method comprises:
• based on a preset time interval, the voltage forward traveling wave sequence, and the voltage reverse traveling wave sequence, calculating the first and second numerical change gradients corresponding to the voltage forward traveling wave sequence and the voltage reverse traveling wave sequence, respectively;
• wherein steps of determining the forward voltage traveling wave energy superposition expression and the reverse voltage traveling wave energy superposition expression based on the first numerical change gradient, the second numerical change gradient, the traveling wave velocity, the line length of the grounding electrode line, the sampling frequency, and the preset step size comprise:
• based on the first numerical change gradient, the second numerical change gradient, the traveling wave velocity, the line length of the grounding electrode line, the sampling frequency, and the preset step size, determining an initial forward voltage traveling wave energy superposition expression corresponding to the first numerical change gradient and an initial reverse voltage traveling wave energy superposition expression corresponding to the second numerical change gradient;
• and
• based on the initial forward voltage traveling wave energy superposition expression and the initial reverse voltage traveling wave energy superposition expression, determining the forward voltage traveling wave energy superposition expression and the reverse voltage traveling wave energy superposition expression, respectively;
• wherein the initial forward voltage traveling wave energy superposition expression represents superposition expression of forward voltage traveling wave energy at any point and any time in the grounding electrode line, and the initial reverse voltage traveling wave energy superposition expression represents superposition expression of reverse voltage traveling wave energy at any point and any time in the grounding electrode line;
• wherein steps of determining the fault distance based on the maximum mutation point in the integral value sequence comprises:
• marking the maximum mutation point in the integral value sequence;
• calculating a superimposed value of a gradient of change in the integral value sequence before the maximum mutation point;
• when the superimposed value is negative, determining that the fault distance is a distance corresponding to the maximum mutation point;
• when the superimposed value is positive, determining that the fault distance is a difference between the line length of the grounding electrode line and a distance corresponding to the maximum mutation point;
• and
• wherein the fault distance is determined exclusively based on the maximum mutation point and the superimposed value of the gradient of change in the integral value sequence before the maximum mutation point, without requiring an identification of a second mutation point from a different observation time window.