All-insulation elbow-shaped terminal head of distribution network automation switch cabinet

Abstract

The invention provides an all-insulation elbow-shaped terminal head of a distribution network automation switch cabinet, which comprises a joint, a lightning arrester, a current transformer, a sensing unit and an early warning unit, the connector is connected with a cable terminal head, the lightning arrester is fixedly connected with the connector in parallel, an insulating layer is arranged between the lightning arrester and the connector, and the sensing unit is arranged in the connector and is in communication connection with the early warning unit; the lightning arrester is used for absorbing a corresponding high-frequency signal through the capacitance characteristic; the current transformer is sleeved on the three-phase body of the cable terminal head, and the distance between the current transformer and the lap joint surface of the connector is at least greater than a preset distance threshold value; the sensing unit is used for monitoring the operation state and the temperature data value of the switch cabinet in real time; the early warning unit is used for generating a corresponding early warning signal when the temperature data value exceeds a preset temperature threshold value or the operation state is abnormal. The heating fault is effectively prevented, the reliability and safety of the switch cabinet are improved, and the fault rate and the maintenance cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fully-insulated elbow-type terminal heads, in particular to a fully-insulated elbow-type terminal head of a distribution network automation switch cabinet. Background Art

[0002] Distribution network automation switchgear is the core asset of modern urban intelligent distribution network. It realizes the monitoring, control and management of power distribution network system through intelligent technology and information communication technology. At the same time, during the operation of distribution network automation switchgear, the fully insulated elbow terminal head frequently has heating failure, which not only affects the normal operation of the switchgear, but also may cause safety accidents.

[0003] Compared with the fully insulated elbow-type terminal head of the distribution network automation switch cabinet, the failure rate is significantly higher and develops faster (within half an hour at the shortest). The failure heat is continuous and obvious, including the burning and cracking of high-voltage insulation pillars, carbonization of the main cable insulation (about 40cm), and some accompanied by burning and smoking. According to statistics, this type of failure often occurs in urban distribution networks with a high cable rate, and the proportion of failures is increasing year by year, affecting the reliability of power supply.

[0004] Statistical results show that this type of failure is not concentrated in a certain brand or region, proving that it is not caused by family defects or maintenance quality. This type of failure occurs when a single phase or multiple phases overheat at the same time. If the wire ear is not tightened, only one phase will be affected and the contact point will melt into a metal lump due to the large contact resistance.

[0005] Compared with ordinary ring network cabinets, the biggest difference between the cable terminal head of the distribution network automation ring network cabinet and the ordinary distribution network switch cabinet is that the terminal head joint surface accessories are equipped with a core-through phase current transformer, and the user measures the three-phase current data in real time. Combined with the serious continuous heating phenomenon, the root cause of the heating failure of the fully insulated elbow-type terminal head of the distribution network automation switch cabinet is electromagnetic induction. The main influencing factors are: the magnetic field of the current transformer affects the equivalent self-inductance value of the terminal head; cross-linked polyethylene cable is conducive to high-frequency harmonic conduction; surface discharge excites severe partial discharge pulse current; high-frequency harmonic pollution under high load current. Summary of the invention

[0006] The purpose of the present invention is to provide a fully insulated elbow-type terminal head for a distribution network automation switch cabinet, so as to solve the technical problem of how to effectively prevent the terminal head of the automation cabinet from overheating failure.

[0007] On the one hand, a fully insulated elbow terminal head of a distribution network automation switch cabinet is provided, comprising:

[0008] A connector, a lightning arrester, a current transformer, a sensor unit and an early warning unit; the connector is connected to a cable terminal head, the lightning arrester is fixed in parallel with the connector, an insulating layer is provided between the lightning arrester and the connector, and the sensor unit is provided in the connector and is in communication connection with the early warning unit;

[0009] The arrester is used to absorb the corresponding high-frequency signal through its capacitance characteristics;

[0010] The current transformer is sleeved on the three-phase body of the cable terminal head, and the distance between the current transformer and the overlapping surface of the joint is at least greater than a preset distance threshold;

[0011] The sensing unit is used to monitor the operating status and temperature data value of the switch cabinet in real time; the early warning unit is used to generate a corresponding early warning signal when the temperature data value exceeds a preset temperature threshold or the operating status is abnormal.

[0012] Preferably, it also includes a transverse guide rail, which is transversely fixed to one side of the cable terminal head;

[0013] A plurality of current transformers are fixed in parallel on the transverse guide rail, and one current transformer is sleeved on a phase body of the cable terminal head.

[0014] Preferably, the current transformer comprises an annular magnetic core, a secondary coil and an annular metal shell;

[0015] The annular magnetic core is fixed in parallel with the secondary coil, the annular metal shell is wrapped around the outside of the annular magnetic core and the secondary coil, and the outer wall of one side of the annular metal shell is connected to the horizontal guide rail.

[0016] Preferably, the annular metal shell comprises an upper shielding portion and a lower shielding portion; the upper shielding portion and the lower shielding portion are stacked and fixed to each other;

[0017] The upper shielding part is an annular aluminum shell, a lower annular groove is arranged on the inner side of the lower part, a shielding layer is arranged on the inner wall of the lower annular groove, and a shielding layer is arranged on the outer wall of the upper shielding part;

[0018] The lower shielding part is an annular aluminum shell, an upper annular groove is arranged on the inner side of the upper part, a shielding layer is arranged on the inner wall of the upper annular groove, and a shielding layer is arranged on the outer wall of the lower shielding part.

[0019] Preferably, a conductive rod is arranged in the joint, one end of the conductive rod is fixed in the joint, and the other end of the conductive rod is connected to the lightning arrester through a stud bolt and a nut; a grounding wire is also arranged on one side of the joint.

[0020] Preferably, a through hole is provided in the arrester, and the stud bolt is fixed in the through hole;

[0021] One side of the lightning arrester is embedded in the joint, and the other side of the lightning arrester is provided with a rear plugging cover and a rear protective cap, the rear plugging cover is embedded in the lightning arrester and covers one side of the through hole, the rear protective cap is fixed on the lightning arrester and wraps the rear plugging cover; an insulating layer is provided between the rear plugging cover and the lightning arrester.

[0022] Preferably, the early warning unit is also used to predict the distribution network operation parameters through a preset parameter analysis model based on the received electromagnetic resonance parameters, wherein the distribution network operation parameters include at least power supply equipment discharge information, line topology information, cable length, load properties and ambient temperature and humidity.

[0023] Preferably, the early warning unit is further used to locate the automation switch cabinet node that may generate heat by comparing the preset normal operating parameters with the distribution network operating parameters when generating the early warning signal.

[0024] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0025] The fully insulated elbow-type terminal head of the distribution network automation switch cabinet provided by the present invention can effectively prevent the occurrence of thermal failure of the fully insulated elbow-type terminal head of the distribution network automation switch cabinet, improve the operating reliability and safety of the switch cabinet, reduce the failure rate and maintenance cost, and provide strong guarantee for the stable operation of the distribution network automation equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0027] Figure 1 It is a schematic diagram of a fully insulated elbow-type terminal head of a distribution network automation switch cabinet in an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of a current transformer in an embodiment of the present invention.

[0029] Figure 3 Schematic diagram of a connector and a lightning arrester in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1FIG. 1 is a schematic diagram of an embodiment of a fully insulated elbow-type terminal head of a distribution network automation switch cabinet provided by the present invention. In this embodiment, it includes:

[0032] A connector 1, a lightning arrester 2, a current transformer 3, a sensor unit and an early warning unit; the connector 1 is connected to a cable terminal 4, the lightning arrester 2 is fixed in parallel with the connector 1, an insulating layer is arranged between the lightning arrester 2 and the connector 1, the sensor unit is arranged in the connector 1 and is connected to the early warning unit for communication; the lightning arrester 2 is used to absorb the corresponding high-frequency signal through its capacitance characteristics; the current transformer 3 is sleeved on the three-phase body of the cable terminal 4, and the distance between the overlapping surface of the current transformer 3 and the connector 1 is at least greater than the preset distance threshold; the sensor unit is used to monitor the operating status and temperature data value of the switch cabinet in real time; the early warning unit is used to generate a corresponding early warning signal when the temperature data value exceeds the preset temperature threshold or the operating status is abnormal. It also includes a transverse guide rail, which is transversely fixed to one side of the cable terminal 4; a plurality of current transformers 3 are fixed in parallel on the transverse guide rail, and one current transformer 3 is sleeved on a phase body of the cable terminal 4. It is understandable that the characteristic impedance of the fully insulated elbow-type terminal head is much greater than that of the cable body, which is prone to refraction and reflection of traveling waves. Especially when the ferromagnetic core of the current transformer 3 is close to the lap surface of the connector 1, it is very easy to form an electromagnetic resonance cavity. Therefore, the installation position of the current transformer 3 is redesigned, and the core is inserted into the three-phase body of the cable terminal head 4, more than 40 cm away from the lap surface of the connector 1, and fixed with a horizontal guide rail. The European rear-insulated lightning arrester 2 is installed in parallel at the terminal head, and the capacitive characteristics of the fully insulated lightning arrester 2 are used to absorb high-frequency signals, and the medium-voltage line equipment of the distribution network is fully insulated to eliminate high-frequency pulse current signals with complex frequency components from the source.

[0033] An embodiment, such as Figure 2 As shown, the current transformer 3 includes an annular magnetic core 301, a secondary coil 302 and an annular metal shell; the annular magnetic core 301 and the secondary coil 302 are fixed in parallel, the annular metal shell is wrapped around the outside of the annular magnetic core 301 and the secondary coil 302, and the outer wall of one side of the annular metal shell is connected to the horizontal guide rail.

[0034] In one embodiment, the annular metal shell includes an upper shielding part 303 and a lower shielding part 304; the upper shielding part 303 and the lower shielding part 304 are stacked and fixed with each other; the upper shielding part 303 is an annular aluminum shell, a lower annular groove is arranged on the inner side of the lower part, a shielding layer is arranged on the inner wall of the lower annular groove, and a shielding layer is arranged on the outer wall of the upper shielding part 303; the lower shielding part 304 is an annular aluminum shell, an upper annular groove is arranged on the inner side of the upper part, a shielding layer is arranged on the inner wall of the upper annular groove, and a shielding layer is arranged on the outer wall of the lower shielding part 304. It can be understood that the annular ferromagnetic core of the current transformer 3 and the secondary coil 302 are placed in the annular metal aluminum shell, and the metal aluminum shell has an excellent high-frequency electromagnetic shielding effect, shielding the magnetic circuit relationship between the terminal head conductor and the ferromagnetic core, significantly reducing the equivalent leakage inductance value of the terminal head conductor, and destroying the electromagnetic resonance condition. The shielding aluminum shell is subjected to an open-and-closed ring cutting treatment, the internal gap is poured with epoxy resin, and the outer layer is poured with epoxy resin to achieve an insulation effect.

[0035] An embodiment, such as Figure 3 As shown, a conductive rod 101 is provided in the joint 1, one end of the conductive rod 101 is fixed in the joint 1, and the other end of the conductive rod 101 is connected to the arrester 2 through a stud bolt 102 and a nut 103; a grounding wire 5 is also provided on one side of the joint 1. A through hole is provided in the arrester 2, and the stud bolt 102 is fixed on the through hole; one side of the arrester 2 is embedded in the joint 1, and a rear plugging cover 201 and a rear protective cap 202 are provided on the other side of the arrester 2, the rear plugging cover 201 is embedded in the arrester 2 and covers one side of the through hole, and the rear protective cap 202 is fixed on the arrester 2 and wraps the rear plugging cover 201; an insulating layer is provided between the rear plugging cover 201 and the arrester 2.

[0036] In one embodiment, the early warning unit is also used to predict the distribution network operation parameters through a preset parameter analysis model according to the received electromagnetic resonance parameters, wherein the distribution network operation parameters at least include power supply equipment discharge information, line topology information, cable length, load properties and ambient temperature and humidity. The early warning unit is also used to locate the automation switch cabinet node that may be heated by comparing the preset normal operation parameters with the distribution network operation parameters when generating the early warning signal. It can be understood that by installing temperature sensors and early warning devices, the operating status and temperature changes of the switch cabinet are monitored in real time. A reasonable temperature threshold is set, and when the temperature exceeds the threshold, the early warning mechanism is automatically triggered, and the operation and maintenance personnel are notified in time to handle it. Through electromagnetic resonance parameters, the distribution network automation cabinet nodes that are prone to terminal head heating are predicted based on the roughly known five major influencing factors, namely, the severity of power supply equipment discharge, line topology relationship, cable length, load properties, and ambient temperature and humidity. Develop targeted maintenance plans, regularly inspect and maintain the switch cabinet, and promptly discover and handle potential heating failure risks. At the same time, artificially destroy electromagnetic resonance conditions and continuously improve preventive measures.

[0037] In a specific embodiment, the approximate length interval of the cable can be derived according to the parallel resonant frequency, so as to locate the node of the automation switch cabinet, as follows

[0038]

[0039]

[0040]

[0041] Among them, L 漏感 is the leakage inductance of the phase current transformer; C0 is YJV22-8.7 / 15kV-3*300mm 2 The capacitance of the cable per kilometer is 0.370μF / km; K is the capacitance correction factor.

[0042] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0043] The fully insulated elbow-type terminal head of the distribution network automation switch cabinet provided by the present invention can effectively prevent the occurrence of thermal failure of the fully insulated elbow-type terminal head of the distribution network automation switch cabinet, improve the operating reliability and safety of the switch cabinet, reduce the failure rate and maintenance cost, and provide strong guarantee for the stable operation of the distribution network automation equipment.

[0044] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A fully insulated elbow terminal head for distribution network automation switch cabinet, It is characterized in that include: A connector, a lightning arrester, a current transformer, a sensor unit and an early warning unit; the connector is connected to a cable terminal head, the lightning arrester is fixed in parallel with the connector, an insulating layer is provided between the lightning arrester and the connector, and the sensor unit is provided in the connector and is in communication connection with the early warning unit; The arrester is used to absorb the corresponding high-frequency signal through its capacitance characteristics; The current transformer is sleeved on the three-phase body of the cable terminal head, and the distance between the current transformer and the overlapping surface of the joint is at least greater than a preset distance threshold; The sensing unit is used to monitor the operating status and temperature data value of the switch cabinet in real time; the early warning unit is used to generate a corresponding early warning signal when the temperature data value exceeds a preset temperature threshold or the operating status is abnormal.

2. The fully insulated elbow terminal as claimed in claim 1, It is characterized in that It also includes a transverse guide rail, which is transversely fixed to one side of the cable terminal head; A plurality of current transformers are fixed in parallel on the transverse guide rail, and one current transformer is sleeved on a phase body of the cable terminal head.

3. The fully insulated elbow terminal as claimed in claim 2, It is characterized in that The current transformer comprises an annular magnetic core, a secondary coil and an annular metal shell; The annular magnetic core is fixed in parallel with the secondary coil, the annular metal shell is wrapped around the outside of the annular magnetic core and the secondary coil, and the outer wall of one side of the annular metal shell is connected to the horizontal guide rail.

4. The fully insulated elbow terminal as claimed in claim 3, It is characterized in that The annular metal shell comprises an upper shielding portion and a lower shielding portion; the upper shielding portion and the lower shielding portion are stacked and fixed to each other; The upper shielding part is an annular aluminum shell, a lower annular groove is arranged on the inner side of the lower part, a shielding layer is arranged on the inner wall of the lower annular groove, and a shielding layer is arranged on the outer wall of the upper shielding part; The lower shielding part is an annular aluminum shell, an upper annular groove is arranged on the inner side of the upper part, a shielding layer is arranged on the inner wall of the upper annular groove, and a shielding layer is arranged on the outer wall of the lower shielding part.

5. The fully insulated elbow terminal as claimed in claim 1, It is characterized in that A conductive rod is arranged in the joint, one end of the conductive rod is fixed in the joint, and the other end of the conductive rod is connected to the lightning arrester through a stud bolt and a nut; a grounding wire is also arranged on one side of the joint.

6. The fully insulated elbow terminal as claimed in claim 5, It is characterized in that A through hole is provided in the arrester, and the stud bolt is fixed in the through hole; One side of the lightning arrester is embedded in the joint, and the other side of the lightning arrester is provided with a rear plugging cover and a rear protective cap, the rear plugging cover is embedded in the lightning arrester and covers one side of the through hole, the rear protective cap is fixed on the lightning arrester and wraps the rear plugging cover; an insulating layer is provided between the rear plugging cover and the lightning arrester.

7. The fully insulated elbow terminal as claimed in claim 1, It is characterized in that The early warning unit is also used to predict the distribution network operation parameters through a preset parameter analysis model according to the received electromagnetic resonance parameters, wherein the distribution network operation parameters at least include power supply equipment discharge information, line topology information, cable length, load properties and ambient temperature and humidity.

8. The fully insulated elbow terminal as claimed in claim 7, It is characterized in that The early warning unit is also used to locate the automation switch cabinet node that may be heated by comparing the preset normal operating parameters with the distribution network operating parameters when generating the early warning signal.

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