A photovoltaic cable sub-health detection and location method based on sstdr technology

Abstract

The invention relates to the technical field of photovoltaic cable detection, specifically a photovoltaic cable sub-health detection and positioning method based on SSTDR technology, which uses a spread spectrum signal with excellent correlation characteristics and a wider spectrum as the incident signal for detection, and is connected to the photovoltaic system DC Busbar, when the cable is damaged, the impedance at the damaged location of the cable will not match the characteristic impedance of the cable, and the incident signal will be reflected at this time, and the reflection coefficient is proportional to the degree of cable damage; the present invention does not require additional sensors to measure Voltage, current, irradiance, temperature and other parameters, according to the change of the impedance value when the DC bus cable appears sub-healthy, through numerical analysis and processing of the cross-correlation value of the incident signal and the reflected signal, the detection of the sub-healthy state of the photovoltaic cable can be realized . Compared with the conventional positioning method, it also has a good effect on the positioning of the cable damage position in the weak damage state.

Description

technical field [0001] The invention relates to the technical field of photovoltaic cable detection, in particular to a photovoltaic cable sub-health detection and positioning method based on SSTDR technology. Background technique [0002] In order to ensure the safe and efficient operation of photovoltaic systems, the monitoring technology of photovoltaic system operating status has attracted extensive attention in the industry. In large-scale photovoltaic power stations, the photovoltaic DC bus (connecting the DC distribution cabinet and the inverter) is generally laid below about 0.8 meters underground, which is prone to soil corrosion, rain erosion, stress, etc., which may cause the aging and damage of the insulation layer. and other problems, we define the cable state with this problem as a sub-health state. Compared with healthy cables, cables in sub-health state generally have no obvious difference in operation state, but there are potential safety hazards. Cables wo...

AI Technical Summary

Problems solved by technology

Spread spectrum time domain frequency domain reflectometry (SSTDR) is a kind of traveling wave method. Currently, SSTDR is used to locate the cable impedance mismatch point mainly by multiplying the signal delay τ and the propagation speed v of the traveling wave in the cable and then dividing. However, since the position of the mismatch point is directly read from the waveform according to the waveform ordinate, if the cable mismatch is small, it is not easy to directly find the impedance mismatch point in the obtained waveform, that is, the signal delay value τ is not easy to find, so Calculating directly according to the formula will produce inaccurate positioning results, and in severe cases, it will directly cause positioning failure

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