CN-122025269-A - Photovoltaic cable for new energy power grid and safety monitoring method thereof

CN122025269ACN 122025269 ACN122025269 ACN 122025269ACN-122025269-A

Abstract

The invention relates to the technical field of photovoltaic cables, in particular to a photovoltaic cable for a new energy power grid and a safety monitoring method thereof, wherein the cable comprises a cable core assembly, a cable core assembly and a cable assembly, wherein the cable core assembly comprises a first cable core and a second cable core which are arranged side by side; the cable core assembly comprises an outer sheath, wherein the outer sheath is coated outside the cable core assembly and comprises a first sheath part for coating a first cable core, a second sheath part for coating a second cable core and connecting ribs for connecting the first sheath part and the second sheath part, and hollow channels are formed in the connecting ribs along the length direction of the cable core assembly and are used for placing temperature sensors. According to the invention, the hollow channel which can penetrate the temperature sensor is arranged in the connecting rib, and the polarity mark structure formed by the protrusion and the groove is arranged on the surface of the outer sheath, so that the problems that a monitoring function cannot be additionally arranged at a later stage, the polarity mark is easy to fade and lose efficacy, and the cost of a monitoring cable is high are avoided.

Inventors

ZHAO LIANGLIANG
ZHU XULIANG
LAI YANAN
TIAN DEGUI
WANG ZONGHAO
XU XUEHUI
ZHANG ZHENFA
JIANG FENG
WU KAI
YU HU
HAN MINGWEI
CHU XUCHAO
LIU JUNBO
LIU ZHONG
Niu Cancan
CHEN MINGSONG
ZHANG JIAN

Assignees

无锡玖开线缆科技集团股份有限公司
玖开特种线缆(上海)有限公司
玖安卡（江苏）智能电力科技有限公司
国网青海省电力公司西宁供电公司
国网山西省电力有限公司太原供电分公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The safety monitoring method for the photovoltaic cable of the new energy power grid is characterized by comprising the following steps of: Collecting partial discharge pulse signals, temperature distribution signals and electrical parameter signals along the photovoltaic cable in real time; Extracting a discharge event from the partial discharge pulse signal, identifying a temperature rise event from the temperature distribution signal, and detecting an electrical parameter event from the electrical parameter signal, wherein the discharge event comprises a discharge time, a discharge position and discharge intensity, the temperature rise event comprises a temperature rise time, a temperature rise position and a temperature rise rate, and the electrical adviser pieces comprise electrical adviser pieces; Comparing the discharge time, the temperature rise time and the electricity adviser pieces time, and identifying whether the time sequence characteristics of the discharge time before the temperature rise time after the temperature rise time and the time sequence characteristics of the electricity adviser pieces time correlated with the discharge time or the temperature rise time exist or not; Calculating the distance between the discharge position and the temperature rise position, and evaluating the space matching degree between the discharge position and the temperature rise position; acquiring an energy conversion relation between the discharge intensity and the temperature rise rate, calculating a theoretical temperature rise rate according to the energy conversion relation, and comparing the theoretical temperature rise rate with the temperature rise rate to obtain an energy consistency result; and generating a safety monitoring result according to the time sequence characteristic, the space matching degree and the energy consistency result.
2. The method for safety monitoring of photovoltaic cables for new energy grids according to claim 1, characterized in that it identifies whether there is a timing characteristic of the discharge moment before the temperature rise moment after and the electrical adviser moment associated with the discharge moment or the temperature rise moment, comprising: Calculating a thermal conduction time range according to the distance between the discharge position and the temperature rise position along the cable path; recording the time difference between the discharge time and the temperature rise time as measured conduction time, and judging that the discharge event and the temperature rise event meet time correlation when the measured conduction time is within the heat conduction time range and the discharge time is earlier than the temperature rise time; Carrying out waveform analysis on the electric adviser pieces corresponding to the electric adviser pieces at the moment, and identifying the waveform form of the electric parameter event; Comparing the waveform of the electric reference event with the discharge time when the waveform of the electric reference event shows an instantaneous pulse form, and judging that the electric reference event is in time correlation with the discharge event if the time difference is smaller than the lower limit of the thermal conduction time range; When the waveform of the electric parameter event shows a continuous fluctuation form, identifying the starting moment and comparing with the temperature rise moment, and if the time difference is smaller than the upper limit of the thermal conduction time range, judging that the electric parameter event is in time correlation with the temperature rise event; and when the discharge event and the temperature rise event meet the time correlation, and the electrical parameter event is correlated with the existence time of the discharge event or the temperature rise event, judging that the time sequence characteristic exists.
3. The safety monitoring method for a photovoltaic cable of a new energy grid according to claim 1, wherein the distance calculation is performed between the discharge position and the temperature rise position, and the evaluation of the spatial matching degree between the discharge position and the temperature rise position comprises: Determining a space range of heat diffusion from the discharge position to the temperature rise position according to the time difference between the discharge time and the temperature rise time and the heat diffusion characteristic of the photovoltaic cable insulating material; acquiring a discharge positioning allowable deviation corresponding to the discharge event and a temperature rise positioning allowable deviation corresponding to the temperature rise event; calculating the actual distance between the discharging position and the temperature rise position along the cable path; and judging the space matching degree of the discharge position and the temperature rise position according to the actual distance in the space range, the discharge positioning allowable deviation and the temperature rise positioning allowable deviation.
4. The method for safety monitoring of a photovoltaic cable for a new energy grid according to claim 1, wherein obtaining an energy conversion relationship between the discharge intensity and the temperature rise rate comprises: selecting a cable sample of the same type as the photovoltaic cable, carrying out a partial discharge experiment, and synchronously collecting the partial discharge signals and the corresponding temperature change data under different discharge intensities; Establishing a corresponding relation between the discharge intensity and the temperature rise rate according to the partial discharge signal and the temperature change data as the energy conversion relation; or acquiring a thermophysical parameter of the photovoltaic cable insulating material, and calculating a theoretical corresponding relation between the discharge intensity and the temperature rise rate according to the thermophysical parameter and a conversion principle of discharge energy and heat to serve as the energy conversion relation.
5. The method for safety monitoring of a photovoltaic cable for a new energy grid according to claim 1, characterized in that calculating a theoretical rate of temperature rise from the energy conversion relationship comprises: Acquiring the discharge time from the discharge events, and acquiring a plurality of discharge events in a preset time period before the discharge time; Counting the sum of the discharge intensities of the plurality of discharge events as an accumulated discharge intensity; Substituting the accumulated discharge intensity into the energy conversion relation, and calculating to obtain a theoretical temperature rise rate.
6. The method for safety monitoring of a photovoltaic cable for a new energy grid according to claim 1, characterized in that calculating a theoretical rate of temperature rise from the energy conversion relationship comprises: When the time sequence characteristic is established and the space matching degree is within a preset range, the discharge intensity is obtained from the discharge event; substituting the discharge intensity into the energy conversion relation, and calculating to obtain a theoretical temperature rise rate; When the time sequence characteristic is not established or the space matching degree is not in a preset range, skipping calculation of the theoretical heating rate; The preset range is determined by a discharge positioning error corresponding to the discharge event and a temperature rise positioning error corresponding to the temperature rise event, the lower limit of the preset range is zero, and the upper limit of the preset range is the sum of the discharge positioning error and the temperature rise positioning error.
7. The method for safety monitoring of a photovoltaic cable for a new energy grid according to claim 1, wherein comparing the theoretical temperature rise rate with the temperature rise rate results in energy consistency results, comprising: Calculating the difference between the theoretical temperature rise rate and the temperature rise rate of the temperature rise event; Acquiring a preset energy judgment threshold, and acquiring the energy consistency result when the difference value is smaller than the energy judgment threshold; the energy judgment threshold is determined according to a temperature measurement error of the photovoltaic cable; Or the energy judgment threshold is determined according to the fitting error of the energy conversion relation; or the energy judgment threshold is adjusted according to the time differential state of the discharge moment and the temperature rise moment.
8. A photovoltaic cable for a new energy grid, characterized in that the safety monitoring method according to any one of claims 1-7 is applied, comprising: the cable core assembly (1) comprises a first wire core (11) and a second wire core (12) which are arranged side by side; the outer sheath (2) is coated outside the cable core assembly (1) and comprises a first sheath part (21) for coating the first cable core (11), a second sheath part (22) for coating the second cable core (12) and connecting ribs (23) for connecting the first sheath part (21) and the second sheath part (22); the connecting ribs (23) are provided with hollow channels (231) along the length direction of the cable core assembly (1), and the hollow channels (231) are used for placing temperature sensors.
9. The photovoltaic cable for a new energy grid according to claim 8, characterized in that the hollow channel (231) is pre-provided with an extractable filler rope (3).
10. The photovoltaic cable for a new energy grid according to claim 8, characterized in that the outer jacket (2) surface is provided with a polarity marking structure (24) comprising protrusions (241) at the first jacket portion (21) surface and grooves (242) at the second jacket portion (22) surface.

Description

Photovoltaic cable for new energy power grid and safety monitoring method thereof Technical Field The invention relates to the technical field of photovoltaic cables, in particular to a photovoltaic cable for a new energy power grid and a safety monitoring method thereof. Background The photovoltaic cable is mainly applied to direct current side, connect equipment such as photovoltaic module, collection flow box, dc-to-ac converter, need expose in outdoor environment for a long time, the photovoltaic cable adopts the twin-core structure generally, correspond direct current transmission's positive pole and negative pole respectively, in the work progress, the polarity of accurate discernment cable is crucial, if the positive negative pole connects the contrary, can lead to generating efficiency to reduce, still probably damage key equipment such as dc-to-ac converter, in addition, the cable is as energy transmission's carrier, insulating ageing, partial discharge, connect bad scheduling problem if can not obtain in time discovery and processing, running state directly influences the security and the generating efficiency of whole power station. Meanwhile, the common cable does not have on-line monitoring capability, operation and maintenance personnel can not find early fault hidden dangers such as insulation degradation, partial discharge and the like in time, the other type of intelligent monitoring cable realizes temperature monitoring through an embedded optical fiber, but the manufacturing cost is obviously increased, an embedded sensor is difficult to repair once damaged, the laid common cable cannot be upgraded and reformed in later period, and the safety monitoring means of the photovoltaic cable in the prior art is isolated and inaccurate in evaluation. The information disclosed in this background section is only for enhancement of understanding of the general background of the disclosure and is not to be taken as an admission or any form of suggestion that this information forms the prior art that is well known to a person skilled in the art. Disclosure of Invention In view of at least one of the technical problems, the invention provides a photovoltaic cable for a new energy power grid and a safety monitoring method thereof, wherein a hollow channel which can penetrate a temperature sensor is arranged in a connecting rib, and a polarity identification structure is arranged on the surface of an outer sheath, so that the problems that the existing common cable cannot be monitored in the later stage, the polarity identification fails and the monitoring cost is high are solved. The invention provides a photovoltaic cable for a new energy power grid, which comprises the following components: The cable core assembly comprises a first cable core and a second cable core which are arranged side by side; The outer sheath is coated outside the cable core assembly and comprises a first sheath part for coating the first cable core, a second sheath part for coating the second cable core and connecting ribs for connecting the first sheath part and the second sheath part; the connecting ribs are provided with hollow channels along the length direction of the cable core assembly, and the hollow channels are used for placing temperature sensors. Further, an extractable filling rope is preset in the hollow channel. Further, the outer jacket surface is provided with a polarity-indicating structure comprising a protrusion on the first jacket portion surface and a recess on the second jacket portion surface. The invention also provides a safety monitoring method of the photovoltaic cable for the new energy power grid, which comprises the following steps: Collecting partial discharge pulse signals, temperature distribution signals and electrical parameter signals along the photovoltaic cable in real time; Extracting a discharge event from the partial discharge pulse signal, identifying a temperature rise event from the temperature distribution signal, and detecting an electrical parameter event from the electrical parameter signal, wherein the discharge event comprises a discharge time, a discharge position and discharge intensity, the temperature rise event comprises a temperature rise time, a temperature rise position and a temperature rise rate, and the electrical adviser pieces comprise electrical adviser pieces; Comparing the discharge time, the temperature rise time and the electricity adviser pieces time, and identifying whether the time sequence characteristics of the discharge time before the temperature rise time after the temperature rise time and the time sequence characteristics of the electricity adviser pieces time correlated with the discharge time or the temperature rise time exist or not; Calculating the distance between the discharge position and the temperature rise position, and evaluating the space matching degree between the discharge position and the temperature rise position; acquiring an energy