CN111896838B - Double-ended traveling wave fault location method based on information feature identification - Google Patents
Double-ended traveling wave fault location method based on information feature identification Download PDFInfo
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Abstract
基于信息特征识别的双端行波故障测距方法，在光电复合电缆两端安装的行波检测装置；依据光电复合电缆的光纤链路是否损坏，分两种情况计算故障测距。采用该方法后在光电复合电缆两端不再需要加装GPS等对时同步装置，而只需要在光电复合电缆两端设置信息特征识别模块，信息特征识别模块为软件模态，不需要额外硬件装置。在光电复合电缆发生故障时，光电复合电缆两端安装的行波检测装置会检测到行波信号，依据光电复合电缆光纤链路是否损坏，分两种情况讨论计算故障测距。光电复合电缆基于本发明测距方法，具有不需要额外加装高精度GPS硬件装置、以及环境适应性强的特点，提高光电复合电缆测距的精确度。
The double-ended traveling wave fault location method based on information feature identification, a traveling wave detection device is installed at both ends of the optoelectronic composite cable; according to whether the optical fiber link of the optoelectronic composite cable is damaged, the fault location is calculated in two cases. After adopting this method, it is no longer necessary to install time synchronization devices such as GPS at both ends of the optoelectronic composite cable, but only the information feature identification module needs to be set at both ends of the optoelectronic composite cable. The information feature identification module is a software mode and does not require additional hardware. device. When the photoelectric composite cable fails, the traveling wave detection device installed at both ends of the photoelectric composite cable will detect the traveling wave signal. According to whether the optical fiber link of the photoelectric composite cable is damaged, the fault location is discussed and calculated in two cases. Based on the ranging method of the present invention, the photoelectric composite cable has the characteristics of not requiring additional high-precision GPS hardware devices and strong environmental adaptability, thereby improving the accuracy of the photoelectric composite cable ranging.
Description
Technical Field
The invention relates to the technical field of photoelectric composite cable fault detection, in particular to a double-end traveling wave fault location method based on information characteristic identification.
Background
The optical fiber technology has the advantages of large transmission information capacity, suitability for anti-interference acquisition in environments such as strong magnetism and the like, and becomes one of strong supports for strong smart power grids and ubiquitous power internet of things. The transformer substation is one of important places of a power network, a large amount of information such as electrical parameters and switch states needs to be monitored, and technologies such as optical fibers and networks are widely applied. In order to quickly and flexibly lay a power pipeline and an optical fiber link, a cable for power transmission and an optical fiber for information transmission are combined to form a hot spot, and a photoelectric composite cable is produced.
The photoelectric composite cable is a novel cable combining an optical cable and a cable together, integrates an optical fiber and a transmission copper wire into a whole to serve as a transmission line, and can solve the problems of broadband access, equipment power consumption, signal transmission and the like. The photoelectric composite cable is suitable for insulating communication optical cables, traffic communication optical cable engineering, square optical cable engineering, overhead optical cable construction, power optical cable engineering, high-altitude optical cable construction and the like. The photoelectric composite cable is subjected to performance test and daily maintenance, the reliability of power transmission and the stability of information transmission are ensured, the adverse effect of the photoelectric composite cable on a power grid is reduced, and the photoelectric composite cable becomes one of the current research and application hotspots. The existing research results show that the photoelectric composite cable combining the optical fiber application technology and the power transmission plays an increasingly important role in the construction of power systems, particularly intelligent transformer substations; meanwhile, the technical staff of the power system has urgent requirements on the rapid and effective detection and recovery of the faults of the photoelectric composite cable.
When the photoelectric composite cable breaks down, traveling waves which are transmitted to two ends of the photoelectric composite cable at the speed of light are generated at a fault point, and the distance between the fault point and one end or two ends of the photoelectric composite cable can be calculated by utilizing the time value of the traveling waves reaching one end or two ends of the cable in the traditional method, so that the fault point is positioned. The single-ended distance measurement principle has high waveform analysis difficulty and poor reliability; although the distance measurement of the two ends is accurate and the reliability is high, the two ends need to have extremely high time synchronization precision requirements, and a GPS device is additionally arranged at the two ends to realize synchronization, so that the cost is high, and the synchronization is easily influenced by the environment.
Disclosure of Invention
In order to quickly and accurately detect and recover the faults of the photoelectric composite cable, the invention provides the double-end traveling wave fault location method based on information characteristic identification, which can quickly and accurately detect the fault points of the photoelectric composite cable.
The technical scheme adopted by the invention is as follows:
the double-end traveling wave fault location method based on information characteristic identification comprises the following steps:
the method comprises the following steps: the traveling wave detection devices are arranged at two ends of the photoelectric composite cable;
step two: according to whether an optical fiber link of the photoelectric composite cable is damaged, calculation is carried out according to two conditions:
1) normal communication of the optical fiber link of the photoelectric composite cable:
s1, when the traveling wave signal is detected by the traveling wave detection device at the information input end of the photoelectric composite cable, marking the corresponding time t of the information startMMeanwhile, the information characteristic identification module is started to identify the information characteristics of the information input end;
s2, capturing the corresponding information characteristic at the information output end of the photoelectric composite cable and recording the time t when the information reachesNMarking the arrival time t of the travelling wave signalWN；
S3, according to the sequence of information arriving at two ends of the photoelectric composite cable, transmitting time delay t in the optical fiber linkdRespectively determining the time difference value delta ti of the optical information reaching the two ends of the photoelectric composite cable;
Δti＝tN-tM-td (1)
the theoretical time difference Δ ti' for the optical information to propagate through the optical fiber link has the following relationship:
wherein: lMNThe total length of the optoelectrical composite cable is shown,
thus obtaining the following components:
wherein: c is the propagation velocity of light, n1Is the refractive index of the glass core light of the optical fiber,
the critical angle at which total reflection of light from the core to the sheath occurs.
S4, according to the formulas (1) and (3), when the information output ends of the photoelectric composite cables are paired, the reference time represents the time tMAccording to the formula (1) and the formula (3), the synchronous time t of the information output end of the photoelectric composite cable is obtainedN′：
S5, reaching time t to informationNAnd a synchronization time tNWhen correcting time synchronization is carried out, namely the system time synchronization of the photoelectric composite cable information output end traveling wave detection device and the output end traveling wave detection device is completed, the time correction error delta t is as follows:
Δt＝tN-tN′ (5)
the time difference value of the fault traveling wave signal reaching the two ends of the photoelectric composite cable is delta tw:
Δtw＝tWN-tWM (6)
wherein: t is tWM、tWNRepresenting the arrival time of the traveling wave signals marked by the traveling wave detection devices at the two ends of the photoelectric composite cable;
s6, carrying out time synchronization by adopting the optical information time correction error in the formula (5), wherein the accurate time difference value delta tw' of the corrected fault traveling wave signal reaching the two ends of the photoelectric composite cable is as follows:
Δtw′＝(tWN-Δt)-tWM (7)
and S7, calculating the distance from the fault point of the photoelectric composite cable to the two ends based on the double-end traveling wave distance measurement principle and the formula (7):
2) the optical fiber link of the photoelectric composite cable is damaged, and the two ends of the photoelectric composite cable can not normally communicate:
step1, marking the corresponding moment t of starting information when the traveling wave detection device at the information input end of the photoelectric composite cable detects the traveling wave signalMMeanwhile, the information characteristic identification module is started to identify the information characteristics of the information input end;
step2, the optical information is transmitted to the fault point via the optical fiber link and then is folded back, and the local terminal is at tMRCapturing the information return time at the time; meanwhile, the opposite end cannot capture the corresponding information characteristics;
step3, calculating the distance from the fault point of the photoelectric composite cable to the information input end based on the relation between the transmission speed of the optical information in the optical fiber link and the time:
the invention relates to a double-end traveling wave fault location method based on information characteristic identification, which has the advantages that:
1) after the method is adopted, GPS and other time synchronization devices are not required to be additionally arranged at the two ends of the photoelectric composite cable, but information characteristic identification modules are only required to be arranged at the two ends of the photoelectric composite cable, are in a software mode, do not need additional hardware devices, are low in cost and are not easily influenced by the environment.
2) The photoelectric composite cable is based on the distance measuring method, has the characteristics of no need of additionally arranging a high-precision GPS hardware device and strong environmental adaptability, and improves the precision of the distance measurement of the photoelectric composite cable.
Drawings
FIG. 1 is a schematic diagram of the method of the present invention for fault location.
FIG. 2 is a flow chart of the method of the present invention.
Detailed Description
According to the double-end traveling wave fault location method based on information feature identification, GPS (global positioning system) and other time synchronization devices are not required to be additionally arranged at the two ends of the photoelectric composite cable after the method is adopted, and only information feature identification modules are required to be arranged at the two ends of the photoelectric composite cable, are in software modes, and do not need additional hardware devices, as shown in figure 1. When the photoelectric composite cable breaks down, traveling wave signals can be detected by traveling wave detection devices arranged at two ends of the photoelectric composite cable. And (4) according to whether the optical fiber link of the photoelectric composite cable is damaged, discussing and calculating according to two conditions. The method specifically comprises the following steps:
the method comprises the following steps: the traveling wave detection devices arranged at the two ends of the photoelectric composite cable can detect traveling wave signals when the photoelectric composite cable breaks down. And the traveling wave detection device adopts a DLXC05 traveling wave detection device.
Step two: according to whether an optical fiber link of the photoelectric composite cable is damaged, calculation is carried out according to two conditions:
1) normal communication of the optical fiber link of the photoelectric composite cable:
s1, when the traveling wave signal is detected by the traveling wave detection device at the information input end of the photoelectric composite cable, marking the corresponding time t of the information startMAnd the arrival time t of the traveling wave signalWM(ii) a And meanwhile, the information characteristic identification module is started to identify the information characteristics of the information input end. The traveling wave detection devices at two ends of the photoelectric composite cable are provided with information characteristic identification modules, the information characteristic identification modules can not only exchange information with the traveling wave detection devices, but also exchange information with an optical fiber link transceiver of the photoelectric composite cable, belong to control and analysis software, and are compiled by using C + + programming language.
S2, the opposite end, namely the information output end of the photoelectric composite cable, captures the corresponding information characteristic and records the time t when the information reaches the time tNMarking the arrival time t of the travelling wave signalWN；
S3, according to the sequence of information arriving at two ends of the photoelectric composite cable, transmitting time delay t in the optical fiber linkdRespectively determining the time difference delta ti of the optical information reaching the two ends of the photoelectric composite cable, wherein the photoelectric composite cable is a cable with a plurality of optical fibersThe optical information propagation time difference Δ ti in the hybrid cable optical fiber link can be calculated by the following formula:
Δti＝tN-tM-td (1)
wherein: when the photoelectric composite cable is laid, the transmission time delay t of the optical fiber link isdThe total length l of the photoelectric composite cable can be checked or actually measuredMNGenerally, the theoretical time difference Δ ti' of the optical information propagating in the optical fiber link has the following relationship:
wherein: lMNRepresenting the total length of the photoelectric composite cable;
thus obtaining the following components:
wherein: c is the propagation velocity of light, and is 3X 108M/s; n is1Is the refractive index of the glass core light of the optical fiber,
the critical angle of total reflection of light from the inner core to the outer sleeve can be obtained by inquiring the parameters of the photoelectric composite cable.
S4, the principle of double-end traveling wave detection is known as follows: the position of the fault occurrence point can be accurately calculated as long as the accurate difference value of the arrival time of the traveling waves at the two ends is known. Therefore, the invention takes the system time of the traveling wave detection device at the information input end of the photoelectric composite cable as the reference time to accurately calculate the time difference of the traveling wave reaching the two ends of the photoelectric composite cable. Traveling wave signal arrival time t marked by traveling wave detection device system at information input end of photoelectric composite cableWMAnd information characterizing time tMAre both directly usable, and are substantially identical.
Therefore, according to the formulas (1) and (3), the time t can be represented by the reference time when the opposite end, namely the information output end of the photoelectric composite cable is pairedMAccording to the formula (1) and the formula (3), the synchronous time t of the information output end of the photoelectric composite cable is obtainedN′：
S5, reaching time t to informationNAnd a synchronization time tNWhen correcting time synchronization is carried out, namely the system time synchronization of the photoelectric composite cable information output end traveling wave detection device and the output end traveling wave detection device is completed, the time correction error delta t is as follows:
Δt＝tN-tN′ (5)
the photoelectric composite cable is based on a double-end traveling wave detection principle, and the time difference value of a fault traveling wave signal reaching two ends of the photoelectric composite cable is delta tw:
Δtw＝tWN-tWM (6)
wherein: t is tWM、tWNRepresenting the arrival time of the traveling wave signals marked by the traveling wave detection devices at the two ends of the photoelectric composite cable;
s6 in the above equation (6), the arrival time t of the traveling wave signal marked by the traveling wave detection device (system) at both ends of the photoelectric composite cableWMAnd tWNIf the time synchronization or the time synchronization is not performed yet, the time synchronization is not reliable, the time synchronization needs to be performed by adopting the optical information time correction error in the formula (5), and the accurate time difference value Δ tw' of the corrected fault traveling wave signal reaching the two ends of the photoelectric composite cable is as follows:
Δtw′＝(tWN-Δt)-tWM (7)
and S7, calculating the distance from the fault point of the photoelectric composite cable to the two ends based on the double-end traveling wave distance measurement principle and the formula (7):
2) the optical fiber link of the photoelectric composite cable is damaged, the two ends of the photoelectric composite cable can not normally communicate, at the moment, a fault point in the photoelectric composite cable generally generates large deformation, and the fault point of the optical fiber link in the photoelectric composite cable is a cable fault point. After optical information at two ends of the optical fiber link enters the link, the information is not transmitted to the opposite end, but weak optical information is folded back and returned from the same end after the information reaches a fault point.
Step1, when the traveling wave detection device at the information input end of the photoelectric composite cable detects a traveling wave signal, marking the corresponding moment t of information startMAnd the arrival time t of the traveling wave signalWMMeanwhile, the information characteristic identification module is started to identify the information characteristics of the information input end;
step2, the optical information is transmitted to the fault point via the optical fiber link and then is folded back, and the local terminal is at tMRCapturing the information return time at the time; meanwhile, the opposite end cannot capture the corresponding information characteristics;
step3, calculating the distance from the fault point of the photoelectric composite cable to the information input end based on the relation between the transmission speed of the optical information in the optical fiber link and the time:
based on the formula, the implementation scheme of the double-end traveling wave fault location method of the photoelectric composite cable based on information synchronization is obtained as follows:
expensive GPS time synchronization devices are not required to be additionally arranged at the two ends of the photoelectric composite cable, and information characteristic identification modules are only required to be arranged at the two ends of the photoelectric composite cable. When the photoelectric composite cable breaks down, the traveling wave detection devices arranged at the two ends of the photoelectric composite cable can detect traveling wave signals and respectively record the time when the traveling wave signals are detectedMoment tWMAnd tWN。
Then, the information characteristic identification module is used for judging whether an optical fiber link of the photoelectric composite cable is damaged or not, and when a traveling wave signal is detected by a traveling wave detection device at the information input end of the photoelectric composite cable, the information starting corresponding moment t is markedMMeanwhile, the information characteristic identification module is started to identify the photoelectric information characteristics of the cable input end, and the photoelectric information which is not returned back is not received within a certain time period; and the opposite end captures the corresponding information characteristics and records the time t when the information reachesN(ii) a The optical fiber link of the optical-electrical composite cable is in communication normally. And calculating the distances from the fault point of the photoelectric composite cable to the two ends according to the formula (8) and the formula (9).
If the traveling wave detection device at the information input end of the photoelectric composite cable detects a traveling wave signal, marking the corresponding moment t of information startingMMeanwhile, the information characteristic identification module is started to identify the photoelectric information characteristics of the information input end of the photoelectric composite cable and receive the returned photoelectric information within a short time; meanwhile, the opposite end cannot capture the corresponding information characteristics; the optical fiber link of the photoelectric composite cable is damaged along with the fault. The distance from the fault point of the photoelectric composite cable to the information input end is calculated by the formula (10).
A control flow diagram for implementing the above method is shown in fig. 2.
Claims (1)
1. The double-end traveling wave fault location method based on information characteristic identification comprises the following steps:
the method comprises the following steps: the traveling wave detection devices are arranged at two ends of the photoelectric composite cable;
step two: according to whether an optical fiber link of the photoelectric composite cable is damaged, calculation is carried out according to two conditions:
1) normal communication of the optical fiber link of the photoelectric composite cable:
s1, when the traveling wave signal is detected by the traveling wave detection device at the information input end of the photoelectric composite cable, marking the corresponding time t of the information startMMeanwhile, the information characteristic identification module is started to identify the information characteristics of the information input end;
s2, capturing the corresponding information characteristic at the information output end of the photoelectric composite cable and recording the time t when the information reachesNMarking the arrival time t of the travelling wave signalWN；
S3, according to the sequence of information arriving at two ends of the photoelectric composite cable, transmitting time delay t in the optical fiber linkdRespectively determining the time difference value delta ti of the optical information reaching the two ends of the photoelectric composite cable;
Δti＝tN-tM-td (1)
the theoretical time difference Δ ti' for the optical information to propagate through the optical fiber link has the following relationship:
wherein: lMNThe total length of the optoelectrical composite cable is shown,
thus obtaining the following components:
wherein: c is the propagation velocity of light, n1Is the refractive index of the glass core light of the optical fiber,
the critical angle of total reflection of light from the inner core to the outer sleeve;
s4, according to the formulas (1) and (3), when the information output ends of the photoelectric composite cables are paired, the reference time represents the time tMAccording to the formula (1) and the formula (3), the synchronous time t of the information output end of the photoelectric composite cable is obtainedN′：
S5, reaching time t to informationNAnd a synchronization time tN' carry out repairAnd (3) when time synchronization is carried out, namely the time synchronization of the system of the photoelectric composite cable information output end traveling wave detection device and the output end traveling wave detection device is completed, wherein a time correction error delta t is as follows:
Δt＝tN-tN′ (5)
the time difference value of the fault traveling wave signal reaching the two ends of the photoelectric composite cable is delta tw:
Δtw＝tWN-tWM (6)
wherein: t is tWM、tWNRepresenting the arrival time of the traveling wave signals marked by the traveling wave detection devices at the two ends of the photoelectric composite cable;
s6, carrying out time synchronization by adopting the optical information time correction error in the formula (5), wherein the accurate time difference value delta tw' of the corrected fault traveling wave signal reaching the two ends of the photoelectric composite cable is as follows:
Δtw′＝(tWN-Δt)-tWM (7)
and S7, calculating the distance from the fault point of the photoelectric composite cable to the two ends based on the double-end traveling wave distance measurement principle and the formula (7):
2) the optical fiber link of the photoelectric composite cable is damaged, and the two ends of the photoelectric composite cable can not normally communicate:
step1, marking the corresponding moment t of starting information when the traveling wave detection device at the information input end of the photoelectric composite cable detects the traveling wave signalMMeanwhile, the information characteristic identification module is started to identify the information characteristics of the information input end;
step2, the optical information is transmitted to the fault point via the optical fiber link and then is folded back, and the local terminal is at tMRCapturing the information return time at the time; meanwhile, the opposite end cannot capture the corresponding information characteristics;
step3, calculating the distance from the fault point of the photoelectric composite cable to the information input end based on the relation between the transmission speed of the optical information in the optical fiber link and the time:
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