CN-121995160-A - Distribution cable insulation aging monitoring method based on traveling wave principle

Abstract

The invention discloses a distribution cable insulation aging monitoring method based on traveling wave principle, which is a novel fault point branch circuit judging method, after judging a fault branch circuit by the method, by further calculating the time difference that the fault initial traveling wave reaches the end point of the branch circuit and a T node, and comparing the time difference of the fault traveling wave transmitted from each connection point of the branch to the line end measuring point and the T node, determining an overhead line section or a cable line section where the fault is located, and finally realizing accurate calculation of the fault distance by using a double-end traveling wave method. The problem of distribution cable defect operation and maintenance that prior art exists can be fully solved, distribution cable operation life cycle can be improved again simultaneously, intelligent degree and the operation and maintenance cost that distribution cable intelligence was patrolled and examined are further reduced. The accurate positioning of the arrival time of the traveling wave is realized by adopting a digital signal processing method combining the neural network wavelet and the Teager energy operator, and the fault distance measurement can be accurately realized.

Inventors

• WANG SHAOLONG
• ZHANG LIZHEN
• MA PENGTAO
• JIANG JUNWEI
• ZHOU YULONG
• WANG SHU
• DING XIAOCHENG

Assignees

• 国网甘肃省电力公司庆阳供电公司

Dates

Publication Date

20260508

Application Date

20241104

Claims (3)

1. 1. A novel fault point branch circuit judging method based on the traveling wave principle is provided, and is characterized in that after a fault branch circuit is judged by the method, the time difference that the initial traveling wave of the fault reaches the end point and the T node of the branch circuit is further calculated, the time difference is compared with the time difference that the traveling wave of the fault propagates from each connection point of the branch circuit to the line end measuring point and the T node, the overhead line section or the cable line section where the fault is located is determined, and finally the accurate calculation of the fault distance is realized by a double-end traveling wave method.
2. 2. The power distribution cable insulation aging monitoring method based on the traveling wave principle according to claim 1 is characterized in that a digital signal processing method combining neural network wavelet with Teager energy operators is provided, first, binary wavelet decomposition is carried out on traveling wave signals, in order to avoid noise interference and quantization errors, a second frequency band is adopted as a ranging frequency band, and Teager energy operators are processed, mutation characteristics are enhanced, and arrival time of traveling waves is accurately positioned.
3. 3. The distribution cable insulation aging monitoring method based on the traveling wave principle according to claim 1 is characterized in that a double-end traveling wave ranging algorithm based on a modulus time difference is provided, the distance from a fault point to a measuring point can be accurately positioned without being influenced by line parameters and time synchronous walking, the accurate line length is only needed to be known, no ranging dead zone is generated, and a single-end ranging algorithm is adopted for a distribution network cable line with branches to accurately judge the branch where the fault occurs and give out the fault distance.

Description

Distribution cable insulation aging monitoring method based on traveling wave principle Technical Field The application belongs to the technical field of power distribution cable fault monitoring, and particularly relates to a power distribution cable insulation aging monitoring method based on a traveling wave principle. Background With the acceleration of the urban process in China, the urban scale is continuously enlarged, the power grid demand is in a trend of high-speed growth, and the distribution line deployment is gradually increased. The distribution cable is buried underground, and some distribution cables are in a calandria mode, so that faults are not easy to detect, and the operation environment is bad. The existing distribution cable is uneven in manufacturing quality, the line is overlong and cannot be comprehensively detected before operation, and particularly in a novel power system, the novel power system is susceptible to short-time overload operation, insulation is susceptible to aging and corrosion, and potential safety hazards are left for operation of a distribution network. The current technical means for detecting the state of the medium-low voltage cable mainly comprises an off-line high-voltage test, the test difficulty is high, the operation and maintenance efficiency is low, and the requirements of the in-station cable lean power failure plan management and the medium-low voltage cable lean management level improvement are difficult to be met. In addition, with the rapid increase of urban power grid load and the increasing shortage of land resources, the phenomena of dense laying, common-ditch laying and communication optical cable intrusion of power transmission and distribution cables are commonly existed, the fireproof and external-damage-preventing measures of distribution cable lines and channels are not in place, the neutral point mode is not modified, the single-phase fault operation of the distribution cable lines leads to the expansion of accidents, the serious loss risk of the section of a cable channel and the occurrence of major power failure accidents. Once a cable is in fire or explosion, significant economic losses are incurred in the city, as well as casualties. Because the cable is buried underground or in a ditch, a great deal of manpower and economic investment is required to find the fault point once the fault occurs. Since the power distribution network is a complex system, various situations such as short circuit, disconnection, etc. may occur during the operation thereof. When these conditions are met, the grid must be serviced or the equipment replaced. If the fault point can be found out rapidly by the technology, the fault time can be shortened greatly and the power supply reliability can be improved. Therefore, the method for positioning the cable faults of the power distribution network is researched, and has very important theoretical and practical significance. Because the distribution cable adopts a three-core unified mode, accurate phase line fault monitoring is difficult. The conventional method comprises an impedance method, a phasor analysis method, a traveling wave method, a partial discharge method and the like, but the fault position is difficult to accurately position due to the fact that branch links of a power distribution network are more, the structure is complex, signal attenuation is serious, and the traveling wave fault positioning method is relatively accurate in the conventional method, but the waveform has chromatic dispersion and attenuation, so that the fault detection method based on the time domain and frequency domain fusion characteristic fixed speed is provided, the arrival time of a wave head is accurately calibrated, the traveling wave speed is determined, and the fault ranging reliability and accuracy of the traveling wave method are improved. Disclosure of Invention The application aims to solve the problem of inaccurate fault positioning of a distribution cable. In order to achieve the above purpose, the application provides a distribution cable insulation aging monitoring method based on the traveling wave principle. The problem of distribution cable defect operation and maintenance that prior art exists can be fully solved, distribution cable operation life cycle can be improved again simultaneously, intelligent degree and the operation and maintenance cost that distribution cable intelligence was patrolled and examined are further reduced. The application solves the problem of the branch link structure of the power distribution complex network through the novel ranging algorithm, so that the single-line accurate positioning effect can be realized under the conditions of multi-layer cable lines and branch links. In addition, in view of the fact that the conventional single-end method utilizes fault traveling waves and fault point reflected waves to perform ranging, the defect is that reflected waves from fault points