阅读说明：本技术 一种基于超声波测距的电缆充油终端油位检测系统及方法 (System and method for detecting oil level of cable oil filling terminal based on ultrasonic ranging ) 是由 张世元 杨刚 谢茜面 王党峰 陈海延 于 2021-07-08 设计创作，主要内容包括：本发明涉及一种基于超声波测距的电缆充油终端油位检测系统及方法,用于检测电缆充油终端的油位高度,系统包括：采集装置,用于采集内腔内的油位信息,采集装置设于内腔的顶端,采集装置包括超声波单元,超声波单元朝向绝缘油设置；接收装置,与采集装置无线信号连接,能够接收采集装置检测并传送的信号,判断油位高度是否低于预设高度。上述技术方案中所提供的检测系统及检测方法,采用超声波检测的方法对绝缘油的油位进行隔空检测,避免电缆充油终端上的高压击穿采集装置；本发明将采集装置和接收装置分开设置,只将功耗小的采集装置设置在电缆充油终端的内腔顶端,利用无线的方式进行采集装置和接收装置之间的数据通讯。(The invention relates to a system and a method for detecting the oil level of a cable oil filling terminal based on ultrasonic ranging, which are used for detecting the oil level height of the cable oil filling terminal, and the system comprises: the collection device is used for collecting oil level information in the inner cavity and arranged at the top end of the inner cavity and comprises an ultrasonic unit which is arranged towards the insulating oil; and the receiving device is in wireless signal connection with the acquisition device, can receive signals detected and transmitted by the acquisition device, and judges whether the oil level height is lower than a preset height. According to the detection system and the detection method provided by the technical scheme, the oil level of the insulating oil is subjected to space detection by adopting an ultrasonic detection method, so that a high-voltage breakdown acquisition device on a cable oil filling terminal is avoided; the acquisition device and the receiving device are separately arranged, only the acquisition device with low power consumption is arranged at the top end of the inner cavity of the cable oil filling terminal, and data communication between the acquisition device and the receiving device is carried out in a wireless mode.)

1. An oil level detection system of a cable oil-filled terminal based on ultrasonic ranging is used for detecting the oil level height of the cable oil-filled terminal, the cable oil-filled terminal comprises an insulating sleeve, a base and a cable, the insulating sleeve is fixedly connected with the base, the insulating sleeve is provided with an inner cavity containing insulating oil, and the cable penetrates into the inner cavity from the base and penetrates through the insulating sleeve; characterized in that the system comprises:

the collection device is used for collecting oil level information in the inner cavity and arranged at the top end of the inner cavity, and comprises an ultrasonic unit which is arranged towards the insulating oil;

and the receiving device is in wireless signal connection with the acquisition device, can receive the signal detected and transmitted by the acquisition device and judges whether the oil level height is lower than a preset height.

2. The system for detecting the oil level of the cable oil-filled terminal based on the ultrasonic ranging as claimed in claim 1, wherein the ultrasonic unit comprises an ultrasonic transmitting sensor and an ultrasonic receiving sensor, and the ultrasonic transmitting sensor and the ultrasonic receiving sensor are respectively positioned at two sides of the cable; the acquisition device further comprises a temperature sensor, and the temperature sensor is electrically connected with the ultrasonic unit.

3. The ultrasonic ranging-based cable oil-filled terminal oil level detection system according to claim 2, wherein the ultrasonic unit further comprises a sensor base disposed around the cable, the ultrasonic transmitting sensor and the ultrasonic receiving sensor being mounted on the sensor base and electrically connected; the top of the insulating sleeve is provided with a cover body, the cover body and an inner cavity of the insulating sleeve form a sealed inner cavity, and the sensor base is installed on one surface, facing the inner cavity, of the cover body.

4. The system for detecting the oil level of a cable-filled terminal based on ultrasonic ranging according to claim 2 or 3, wherein the installation centers of the ultrasonic wave transmitting sensor, the cable and the ultrasonic wave receiving sensor are on the same straight line.

5. The system for detecting the oil level of the cable oil-filled terminal based on the ultrasonic ranging as claimed in claim 1, 2 or 3, wherein the collecting device further comprises a power taking unit, and the power taking unit comprises an open-loop power taking ring, a control circuit and an energy storage capacitor; the electricity taking unit is electrically connected with the ultrasonic unit.

6. The system for detecting the oil level of the cable oil-filled terminal based on the ultrasonic ranging as claimed in claim 1, 2 or 3, wherein the receiving device is arranged on a ground terminal or the ground and comprises a wireless communication unit, an arithmetic unit and a power supply unit, and the wireless communication unit is in wireless communication connection with the acquisition device; the arithmetic unit calculates the signal sent by the acquisition device and judges the height change of the oil level; the power supply unit is connected with the wireless communication unit and the operation unit.

7. A method for detecting the oil level of a cable oil filling terminal based on ultrasonic ranging is characterized by comprising the following steps:

providing an acquisition device for acquiring oil level information in an inner cavity of a cable oil filling terminal, arranging the acquisition device at the top end of the inner cavity, and arranging an ultrasonic unit in the acquisition device to face insulating oil;

providing a receiving device in wireless signal connection with the acquisition device;

detecting the oil level through the collecting device, and transmitting a detected signal to the receiving device;

and receiving the signal detected and transmitted by the acquisition device through the receiving device, and judging whether the oil level height is lower than a preset height.

8. The method of claim 7, wherein the ultrasonic unit comprises an ultrasonic transmitting sensor and an ultrasonic receiving sensor;

the step of positioning the collection device at the top end of the lumen comprises:

arranging an ultrasonic transmitting sensor in the acquisition device at one side of a cable, and arranging an ultrasonic receiving sensor in the acquisition device at the other side of the cable;

the acquisition device comprises a temperature sensor;

the step of positioning the collection device at the top end of the lumen comprises:

and electrically connecting a temperature sensor with the ultrasonic unit, and detecting the temperature in the inner cavity through the temperature sensor.

9. The method of claim 8,

the ultrasonic unit further comprises a sensor base;

the step of disposing the collection device at the top end of the lumen further comprises:

mounting the ultrasonic transmitting sensor and the ultrasonic receiving sensor on the sensor base and electrically connecting; mounting the sensor base on the top of the inner cavity and surrounding the cable, so that the ultrasonic transmitting sensor and the ultrasonic receiving sensor are positioned on two sides of the cable;

and the installation centers of the ultrasonic transmitting sensor, the cable and the ultrasonic receiving sensor are arranged on the same straight line.

10. The method of claim 7,

the step of disposing the collection device at the top end of the lumen further comprises:

providing a power taking unit, wherein the power taking unit comprises an open-loop power taking ring, a control circuit and an energy storage capacitor, and is electrically connected with the ultrasonic unit;

the step of providing a receiving device in wireless signal connection with the acquisition device further comprises:

arranging the receiving device at the grounding end of the cable oil filling terminal or the ground;

the receiving device comprises a wireless communication unit, an arithmetic unit and a power supply unit;

setting the wireless communication unit to be in wireless communication connection with the acquisition device; calculating the signal sent by the acquisition device through the operation unit, and judging the height change of the oil level; and the power supply unit is connected with the wireless communication unit and the operation unit.

Technical Field

The invention relates to the technical field of power monitoring, in particular to a system and a method for detecting an oil level of a cable oil filling terminal based on ultrasonic ranging.

Background

With the heavy investment of China on economic construction, the power demand is continuously rising, the power construction is rapidly developed, particularly, the construction of high-voltage and ultrahigh-voltage power grids at present, the demand of crosslinked polyethylene insulated power cables with the voltage level of 110kV or above is increasingly increased, and the rapid development of cable accessories is promoted. Cable outdoor terminations are the primary cable accessories by which underground cables are securely connected to the high voltage transmission lines on the high voltage transmission towers.

The current cable terminal products comprise a fully prefabricated dry-type silicon rubber outdoor terminal and an oil-filled terminal, and the oil-filled terminal is widely used. Most of the oil-filled terminal faults are terminal voltage-resistant faults caused by loss of oil filling in the terminal. At the present stage, no better technical means for detecting the oil level of the terminal head exists. The main reasons are that: the cable terminal belongs to the core equipment of a high-voltage cable, the top end and the tail end of the cable terminal have high voltage of more than 10 ten thousand volts, and the cable terminal cannot be measured by using a conventional detection technology.

Disclosure of Invention

The invention aims to overcome the defect that the oil level of insulating oil in a cable terminal cannot be detected in the prior art, and provides a system and a method for detecting the oil level of a cable oil-filled terminal based on ultrasonic ranging.

In order to achieve the purpose, the invention adopts the following technical scheme:

an oil level detection system of a cable oil-filled terminal based on ultrasonic ranging is used for detecting the oil level height of the cable oil-filled terminal, the cable oil-filled terminal comprises an insulating sleeve, a base and a cable, the insulating sleeve is fixedly connected with the base, the insulating sleeve is provided with an inner cavity containing insulating oil, and the cable penetrates into the inner cavity from the base and penetrates through the insulating sleeve; the system comprises:

the collection device is used for collecting oil level information in the inner cavity and arranged at the top end of the inner cavity, and comprises an ultrasonic unit which is arranged towards the insulating oil;

and the receiving device is in wireless signal connection with the acquisition device, can receive the signal detected and transmitted by the acquisition device and judges whether the oil level height is lower than a preset height.

Preferably, the ultrasonic unit comprises an ultrasonic transmitting sensor and an ultrasonic receiving sensor, and the ultrasonic transmitting sensor and the ultrasonic receiving sensor are respectively positioned at two sides of the cable; the acquisition device further comprises a temperature sensor, and the temperature sensor is electrically connected with the ultrasonic unit.

Preferably, the ultrasonic unit further comprises a sensor base, the sensor base is arranged around the cable, and the ultrasonic transmitting sensor and the ultrasonic receiving sensor are mounted on the sensor base and electrically connected; the top of the insulating sleeve is provided with a cover body, the cover body and an inner cavity of the insulating sleeve form a sealed inner cavity, and the sensor base is installed on one surface, facing the inner cavity, of the cover body.

Preferably, the installation centers of the ultrasonic wave transmitting sensor, the cable and the ultrasonic wave receiving sensor are on the same straight line.

Preferably, the collecting device further comprises a power taking unit, wherein the power taking unit comprises an open-loop power taking ring, a control circuit and an energy storage capacitor; the electricity taking unit is electrically connected with the ultrasonic unit.

Preferably, the receiving device is arranged on a ground end or the ground and comprises a wireless communication unit, an operation unit and a power supply unit, and the wireless communication unit is in wireless communication connection with the acquisition device; the arithmetic unit calculates the signal sent by the acquisition device and judges the height change of the oil level; the power supply unit is connected with the wireless communication unit and the operation unit.

The invention also provides a method for detecting the oil level of the cable oil-filled terminal based on ultrasonic ranging, which comprises the following steps:

providing an acquisition device for acquiring oil level information in an inner cavity of a cable oil filling terminal, arranging the acquisition device at the top end of the inner cavity, and arranging an ultrasonic unit in the acquisition device to face insulating oil;

providing a receiving device in wireless signal connection with the acquisition device;

detecting the oil level through the collecting device, and transmitting a detected signal to the receiving device;

and receiving the signal detected and transmitted by the acquisition device through the receiving device, and judging whether the oil level height is lower than a preset height.

Preferably, the ultrasonic unit includes an ultrasonic wave transmitting sensor and an ultrasonic wave receiving sensor;

the step of positioning the collection device at the top end of the lumen comprises:

arranging an ultrasonic transmitting sensor in the acquisition device at one side of a cable, and arranging an ultrasonic receiving sensor in the acquisition device at the other side of the cable;

the acquisition device comprises a temperature sensor;

the step of positioning the collection device at the top end of the lumen comprises:

and electrically connecting a temperature sensor with the ultrasonic unit, and detecting the temperature in the inner cavity through the temperature sensor.

Preferably, the ultrasonic unit further comprises a sensor mount;

the step of disposing the collection device at the top end of the lumen further comprises:

mounting the ultrasonic transmitting sensor and the ultrasonic receiving sensor on the sensor base and electrically connecting; mounting the sensor base on the top of the inner cavity and surrounding the cable, so that the ultrasonic transmitting sensor and the ultrasonic receiving sensor are positioned on two sides of the cable;

and the installation centers of the ultrasonic transmitting sensor, the cable and the ultrasonic receiving sensor are arranged on the same straight line.

Preferably, the step of disposing the collection device at the top end of the lumen further comprises:

providing a power taking unit, wherein the power taking unit comprises an open-loop power taking ring, a control circuit and an energy storage capacitor, and is electrically connected with the ultrasonic unit;

the step of providing a receiving device in wireless signal connection with the acquisition device further comprises:

arranging the receiving device at the grounding end of the cable oil filling terminal or the ground;

the receiving device comprises a wireless communication unit, an arithmetic unit and a power supply unit;

setting the wireless communication unit to be in wireless communication connection with the acquisition device; calculating the signal sent by the acquisition device through the operation unit, and judging the height change of the oil level; and the power supply unit is connected with the wireless communication unit and the operation unit.

Compared with the prior art, the invention has the beneficial effects that:

according to the detection system and the detection method provided by the technical scheme, based on the characteristics of the cable oil filling terminal and the insulating oil, the oil level of the insulating oil is subjected to space detection by adopting an ultrasonic detection method, so that a high-voltage breakdown acquisition device on the cable oil filling terminal is avoided;

in addition, the acquisition device and the receiving device are separately arranged, only the acquisition device with low power consumption is arranged at the top end of the inner cavity of the cable oil filling terminal, and meanwhile, the data communication between the acquisition device and the receiving device is carried out in a wireless mode, so that a high-voltage breakdown detection system on the cable oil filling terminal is avoided.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural diagram of a detection system according to an embodiment of the present invention.

Fig. 2 is an enlarged view of fig. 1 at a, wherein an angle B is a reflection angle of the ultrasonic wave transmission sensor.

Fig. 3 is a partial structural view of the sensing system shown in fig. 1, showing a reflection path of ultrasonic waves after the insulating oil level is lowered.

Fig. 4 is a schematic view of a collecting device according to an embodiment of the present invention.

Fig. 5 is a schematic structural view of an open-loop power extraction ring according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a receiving device according to an embodiment of the present invention.

Description of reference numerals:

10. a cable oil fill terminal; 11. an insulating sleeve; 12. a cover body; 13. an inner cavity; 14. insulating oil; 15. a base; 16. a cable; 17. a ground terminal;

20. a collection device; 21. a sensor base; 22. an ultrasonic emission sensor; 23. an ultrasonic receiving sensor; 24. a power taking unit; 241. an open-loop power take-off ring; 242. an inductor coil; 243. a control circuit; 244. an energy storage capacitor;

30. a receiving device; 31. a wireless communication unit; 32. an arithmetic unit; 33. a power supply unit.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Fig. 1 is a schematic structural view of an embodiment of the oil level detection system for a cable oil-filling terminal according to the present invention. The detection system is used to detect the oil level height of the cable-filled terminal 10. Generally, the cable oil-filled terminal 10 comprises an insulating sleeve 11, a base 15 and a cable 16, wherein the insulating sleeve 11 is fixedly connected with the base 15, the insulating sleeve 11 is provided with an inner cavity 13 containing insulating oil 14, the cable 16 penetrates into the inner cavity 13 from the base and penetrates through the insulating sleeve 11, the inner insulation and the outer insulation of the cable oil-filled terminal 10 are respectively treated, the insulating sleeve 11 is outer insulation and can adopt a porcelain sleeve or a composite insulating sleeve 11, the inner insulation adopts a prefabricated stress cone to control an electric field, the insulating oil 14 can adopt silicon oil or polyisobutylene liquid insulating oil 14, the insulating sleeve 11 and the base are hermetically installed to form a sealed inner cavity 13, and the insulating oil 14 is located in the inner cavity 13 to play a further insulating role. In some severe environments, the insulating sleeve 11 itself or the sealing part with the base is cracked, so that the insulating oil 14 in the inner cavity 13 is lost, and the terminal voltage-resistant fault is caused.

The system comprises: the acquisition device 20 is used for acquiring oil level information in the inner cavity 13, the acquisition device 20 is arranged at the top end of the inner cavity 13, and the acquisition device 20 comprises an ultrasonic unit which is arranged towards the insulating oil 14; and the receiving device 30 is in wireless signal connection with the acquisition device 20, can receive signals detected and transmitted by the acquisition device 20, and judges whether the oil level height is lower than a preset height.

Outdoor cable oil charge terminal 10 generally has the high pressure more than 100KV, 14 oil level to insulating oil in inner chamber 13 detect, can only adopt the form of separating empty detection between insulating oil 14 liquid level and the sensor, it is general for ultrasonic wave or light wave to separate empty detection mode, and insulating oil 14 is general for transparent material, great error appears easily in the light wave measurement, consequently, an acquisition device 20 for gathering the oil level information in inner chamber 13 includes the ultrasonic unit, specifically, acquisition device 20 wholly is located the top of inner chamber 13, be at same height, avoid appearing the voltage difference, the ultrasonic unit sets up towards insulating oil 14.

In addition, in the embodiment of the present invention, the acquisition device 20 and the receiving device 30 are separately arranged, only the acquisition device 20 with low power consumption is arranged at the top end of the inner cavity 13 of the cable oil-filled terminal 10, and meanwhile, data communication between the acquisition device 20 and the receiving device 30 is performed in a wireless manner, so as to avoid high voltage breakdown of the detection system on the cable oil-filled terminal 10.

As shown in fig. 2 and 3, the ultrasonic unit includes an ultrasonic transmitting sensor 22 and an ultrasonic receiving sensor 23, the ultrasonic transmitting sensor 22 and the ultrasonic receiving sensor 23 are respectively located at two sides of the cable, and the ultrasonic waves are reflected on the surface of the insulating oil 14 so that the ultrasonic receiving sensor 23 can receive the ultrasonic waves emitted by the ultrasonic transmitting sensor 22. The existing ultrasonic sensor mainly adopts a direct reflection detection mode, generally is a single-head sensor combining a transmitting end and a receiving end, or the transmitting end and the receiving end are arranged on the same side; the ultrasonic sensors have a sound wave emission angle, such as an angle B shown in fig. 2 and fig. 3, a general sound wave emission angle is 60 ° to 120 °, some sensors have a narrower sound wave emission angle of 6 °, for a narrow inner cavity 13 in the insulating sleeve 11, the emitted ultrasonic waves are reflected by the wall of the inner cavity 13 and the cable 16, and the receiving end receives the ultrasonic waves reflected by the two arms of the narrow cavity, so that the distance measurement fails. Therefore, in the present embodiment, the transmitting end and the receiving end of the ultrasonic sensor are separated, the ultrasonic transmitting sensor 22 and the ultrasonic receiving sensor 23 are adopted and respectively arranged on two sides of the cable 16, the ultrasonic part emitted by the ultrasonic transmitting sensor 22 is isolated by the cable 16, only the ultrasonic reflected by the surface of the insulating oil 14 can be received by the ultrasonic receiving sensor 23 on the other side of the cable, and the condition that the ultrasonic reflected by the cable or the inner cavity wall is received by the ultrasonic receiving sensor 23 does not exist. The ultrasonic wave receiving sensor and the ultrasonic wave transmitting sensor of the present embodiment may be sensors having a sound wave transmission angle B of about 60 °.

Preferably, as shown in fig. 2 and 3, the centers of installation of the ultrasonic wave transmitting sensor 22, the cable 16 and the ultrasonic wave receiving sensor 23 are on the same straight line, and only the ultrasonic wave reflected by the surface of the insulating oil 14 can be received by the ultrasonic wave receiving sensor 23.

In order to facilitate the installation of the ultrasonic transmitting sensor 22 and the ultrasonic receiving sensor 23, the ultrasonic unit further comprises a sensor base 21, and the sensor base 21 can be of an arc-shaped or annular structure and is arranged around the cable 16; the ultrasonic transmitting sensor 22 and the ultrasonic receiving sensor 23 are mounted on the sensor base 21 and electrically connected, and the electric connection is wired electric connection, so that the connection mode is simple, and the processing difficulty is low. When the sensor base 21 is arc-shaped, the ultrasonic wave transmitting sensor 22 and the ultrasonic wave receiving sensor 23 are respectively located at both ends of the sensor base 21, and are located at both sides of the cable 16. When the sensor base is in a circular ring shape, the cable penetrates through the through hole in the middle of the sensor base. One or more of a sensor control circuit 243, a wireless communication chip and a power-taking unit 24 can be further arranged on the sensor base 21, so that the heights of all parts of the collecting device 20 are basically consistent. The wireless communication technology adopted by the system of the present embodiment is known in the related art, and is not described herein again.

Specifically, the top of the insulating sleeve 11 is provided with a cover 12, the cover 12 and the inner cavity of the insulating sleeve 11 form a sealed inner cavity 13, the sensor base 21 is installed on one surface of the cover 12 facing the inner cavity 13, the sensor base 21 can be made of an insulating material, and is fixed with the cover 12 made of a metal material through a plastic screw or a buckle, or can be fixed on one surface of the cover 12 facing the inner cavity 13 in a bonding manner.

The collecting device 20 located in the inner cavity 13 needs to supply power, and the inner cavity 13 has a small space, and cannot be provided with a large power supply, and cannot meet the requirement of long-time monitoring, so as shown in fig. 4 and 5, the power taking unit 24 of the present embodiment includes an open-loop power taking ring 241, a control circuit 243, and an energy storage capacitor 244; the electricity taking unit 24 is electrically connected with the ultrasonic unit, wherein the electric connection is wired connection, and no voltage difference exists because the electric connection is at the same height. The open-loop power-taking ring 241 comprises a mutual inductor with built-in magnetic steel, an inductance coil 242 is wound on the surface of the mutual inductor, power is taken by utilizing the magnetic field of a cable, a control circuit 243 comprises a rectifying and filtering circuit, an MPPT control protection circuit and a voltage-stabilizing output circuit, and an energy-storing capacitor 244 can be arranged on the control circuit 243 or can be arranged independently and is electrically connected with the control circuit 243. The input end of the rectifying and filtering circuit is connected with the output end of the open-loop power taking ring 241, the output end of the rectifying and filtering circuit is connected with the MPPT control protection circuit, full-wave rectification and filtering functions can be achieved, and alternating current voltage output by the open-loop power taking ring 241 is converted into direct current power.

As shown in fig. 6, the receiving device 30 is disposed on the ground 17 or ground, and includes a wireless communication unit 31, an operation unit 32 and a power supply unit 33, wherein the wireless communication unit 31 is in wireless communication connection with the collecting device 20; the arithmetic unit 32 calculates the signal sent by the acquisition device 20 and judges the height change of the oil level; the specific judgment process is as follows: the ultrasonic wave is sent from the ultrasonic transmitting sensor, the distance from the liquid level of the insulating oil to the top end of the inner cavity is calculated to be larger, and if the distance exceeds a set threshold value, an alarm is sent. After the detection system is assembled, the corresponding value of the time interval t can be tested when the height of the insulating oil liquid level is equal to the set threshold value, so that the distance threshold value from the insulating oil liquid level to the top end of the inner cavity corresponds to the time interval threshold value.

Since different temperatures have an influence on the propagation velocity of the ultrasound waves, the acquisition device may further comprise a temperature sensor (not shown) for detecting the temperature in the lumen in order to calibrate the detection result of the ultrasound unit. The sound propagation velocity formula v is (331.4+0.607T), and the formula for the path L is substituted. Because the inner chamber is the airtight environment, its interior humidity is comparatively stable, does not consider the influence of humidity change to sound propagation speed for the time.

The power supply unit 33 is connected to the wireless communication unit 31 and the arithmetic unit 32. At this time, the receiving device 30 and the collecting device 20 are in wireless communication, no voltage difference exists, the power supply unit 33 can be a large-sized storage battery, or the receiving device 30 is directly connected to the commercial power.

The embodiment is based on the detection system, and further provides a method for detecting the oil level of the cable oil-filled terminal 10 based on ultrasonic ranging, which includes:

providing an acquisition device 20 for acquiring oil level information in an inner cavity 13 of the cable oil filling terminal 10, arranging the acquisition device 20 at the top end of the inner cavity 13, arranging an ultrasonic unit in the acquisition device 20 to face the insulating oil 14, and measuring distance by using the ultrasonic unit;

the method comprises the following steps: arranging an ultrasonic transmitting sensor 22 in the acquisition device 20 at one side of the cable, and arranging an ultrasonic receiving sensor 23 in the acquisition device 20 at the other side of the cable;

the steps further include: electrically connecting a temperature sensor (not shown) to the ultrasonic unit, the temperature in the lumen being detected by the temperature sensor;

the method comprises the following steps: the ultrasonic wave transmitting sensor 22 and the ultrasonic wave receiving sensor 23 are mounted on the sensor base 21 and electrically connected; the sensor base 21 is arranged on the top of the inner cavity 13 and surrounds the cable, so that the ultrasonic transmitting sensor 22 and the ultrasonic receiving sensor 23 are positioned on two sides of the cable; preferably, the step further comprises: the ultrasonic transmitting sensor 22, the cable and the ultrasonic receiving sensor 23 are arranged on the same straight line, the ultrasonic wave emitted by the ultrasonic transmitting sensor 22 is partially isolated by the cable and partially reflected by the surface of the insulating oil 14, and the ultrasonic wave reflected by the surface of the insulating oil 14 can be received by the ultrasonic receiving sensor 23 on the other side of the cable.

The steps further include: the power taking unit 24 is provided, and the power taking unit 24 includes an open-loop power taking ring 241, a control circuit 243 and an energy storage capacitor 244, and electrically connects the power taking unit 24 with the ultrasonic unit to supply power to the acquisition device 20.

Providing a receiving device 30 connected with the acquisition device 20 in a wireless signal manner; specifically, the method comprises the following steps: the wireless communication unit 31 is in wireless communication connection with the acquisition device 20, so that the problem of voltage difference between the receiving device 30 and the acquisition device 20 is solved, and the power supply unit 33 is connected with the wireless communication unit 31 and the operation unit 32 to supply power to the receiving device 30.

Oil level detection is performed by the collection device 20, and the detected signal is transmitted to the receiving device 30;

receiving the signal detected and transmitted by the collecting device 20 through the receiving device 30, and determining whether the oil level is lower than the preset level, wherein the determining process is as described above;

the content of the signal comprises a time interval t from the ultrasonic transmitting sensor to the ultrasonic receiving sensor for receiving the signal and the temperature information of the inner cavity detected by the temperature sensor, so that the oil level height is calculated and judged, the oil level height is compared with a set threshold value, whether the oil level height is lower than the preset height is judged, and if the oil level height is lower than the preset height, an alarm is sent.

The step comprises that the wireless communication unit 31 is in wireless communication connection with the acquisition device 20; the signal sent by the collection device 20 is calculated by the arithmetic unit 32, and the change in the oil level height is determined. The arithmetic unit can adopt a conventional arithmetic chip, and the arithmetic requirement is met.

The detection method of the embodiment specifically comprises the following steps:

the system is well installed, a sensor base of the acquisition device is fixed at the top of the inner cavity, the positions of the ultrasonic transmitting sensor, the ultrasonic receiving sensor, the temperature sensor, the power taking unit and the like are determined, and the liquid level of the insulating oil can be measured after 15 hours of oil injection into the inner cavity. The ultrasonic transmitting sensor transmits ultrasonic waves, the ultrasonic waves reflected by the liquid level of the insulating oil can be received by the ultrasonic receiving sensor on the other side of the cable only, a time interval t is obtained, the current sound propagation speed V is judged according to the temperature detected by the temperature sensor, the path L from the ultrasonic transmitting sensor to the liquid level of the insulating oil to the ultrasonic receiving sensor is calculated, the height from the liquid level of the insulating oil to the top end of the inner cavity is judged, if the insulating oil leaks, the time interval t detected by the acquisition device is lengthened, the path L is lengthened, the height from the liquid level of the insulating oil to the top end of the inner cavity is judged to change, if the information received by the receiving device is judged, the time interval t detected by the acquisition device is larger than a set time threshold value, the height from the liquid level of the insulating oil to the top end of the inner cavity is calculated to be lower than a set distance threshold value, and the receiving device judges that the insulating oil leaks, the receiving device can send an alarm to the outside through the wireless communication unit to remind a worker to check in time.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.