Direct current wall bushing test method under large temperature difference working condition

Abstract

The invention discloses a direct-current wall bushing test method under a large temperature difference working condition, which comprises the following steps of: when a direct-current wall bushing is connected or offline, implanting a hot oil circulating pipe into one side of the direct-current wall bushing, and simulating the working condition of the indoor side of the direct-current wall bushing by adjusting the temperature of hot oil; a liquid nitrogen circulating pipe is implanted into the other side of the direct-current wall bushing, and the working condition of the outdoor side of the direct-current wall bushing is simulated by adjusting the temperature of liquid nitrogen; and carrying out a direct current voltage test on the direct current wall bushing under different large temperature difference temperature combinations of the temperature of the hot oil and the temperature of the liquid nitrogen, and carrying out partial discharge measurement. The invention essentially provides a direct-current voltage test method capable of simulating the field actual large-temperature-difference working condition of the direct-current wall bushing, and compared with the prior art, the direct-current voltage test method is more in line with the field reality of a cold region and is more beneficial to the electrical insulation examination of the direct-current wall bushing in the field of extra-high-voltage direct-current transmission.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-high voltage direct current power transmission, and in particular to a direct current wall bushing test method under large temperature difference working conditions. Background Art

[0002] The DC wall bushing in converter stations belongs to the field of high-end equipment technology. Specifically, it involves ultra-high voltage DC transmission technology. This type of equipment is one of the key components in the DC transmission system. It is used to connect the high-voltage equipment inside the converter station with the external transmission line, and plays the role of electrical isolation and mechanical support. The technical level of the DC wall bushing directly affects the reliability and safety of the entire DC transmission system.

[0003] One end of the DC wall bushing in the converter station is placed outdoors, and the other end is placed indoors. The temperature of the indoor side of the DC wall bushing is constant. However, in northern my country, the outdoor temperature is very low in winter, and can reach dozens of degrees below zero under extreme conditions. This causes the internal temperature of the indoor side of the DC wall bushing to be significantly higher than that of the outdoor side, while the internal temperature of the outdoor side bushing is very low. This is a large temperature difference condition. Under such a large temperature difference condition, the existence, transfer, and disappearance of the solid insulation space charge inside the DC wall bushing will be affected, making the DC wall bushing prone to accidents.

[0004] The existing DC voltage test technology for DC wall bushings can only perform DC voltage and partial discharge measurements on the entire DC wall bushing under a constant external environment, and cannot cope with the above-mentioned large temperature difference conditions.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a DC wall bushing test method under large temperature difference conditions, wherein: When the DC wall bushing is handed over or offline, a hot oil circulation pipe is implanted into one side of the DC wall bushing, and the temperature of the hot oil is adjusted to simulate the working conditions of the indoor side of the DC wall bushing; A liquid nitrogen circulation pipe is further implanted into the other side of the DC wall bushing, and the working conditions of the outdoor side of the DC wall bushing are simulated by adjusting the temperature of the liquid nitrogen; Under different temperature combinations of hot oil temperature and liquid nitrogen temperature, DC voltage test and partial discharge measurement are carried out on the DC wall bushing.

[0007] Preferably, the method specifically comprises the following steps: S100, when the DC wall bushing is handed over or taken offline, under the condition that bushing end grading rings are provided at both ends of the DC wall bushing, the bushing flange in the middle of the DC wall bushing is connected to the first end of the partial discharge measurement impedance, and the second end of the partial discharge measurement impedance is grounded; S200, connecting the partial discharge measurement impedance to the DC partial discharge tester; S300, inserting an inner current-carrying conductor into a DC wall bushing, wherein two ends of the inner current-carrying conductor extend out of the bushing end grading rings provided at two ends of the DC wall bushing; S400, a hot oil circulation pipe and a liquid nitrogen circulation pipe are respectively inserted from the outside to the inside at both ends of the current-carrying conductor in the casing; wherein the current-carrying conductor in the casing on one side of the hot oil circulation pipe is connected to a high-voltage DC power supply; S500, adjusting the temperature of the hot oil in the hot oil circulation pipe; S600, adjusting the temperature of liquid nitrogen in the liquid nitrogen circulation tube; S700, under different temperature combinations of hot oil temperature and liquid nitrogen temperature, uses high voltage DC power supply and DC partial discharge tester to conduct DC voltage test on DC wall bushing and perform partial discharge measurement.

[0008] Preferably, The hot oil circulation pipe is controlled by a hot oil circulation controller to adjust the temperature of the hot oil and the circulation of the hot oil in the hot oil circulation pipe.

[0009] Preferably, The liquid nitrogen circulation pipe is controlled by a liquid nitrogen circulation controller to adjust the temperature of the liquid nitrogen and the circulation of the liquid nitrogen in the liquid nitrogen circulation pipe.

[0010] Preferably, The hot oil circulation controller and the liquid nitrogen circulation controller both include a single chip microcomputer.

[0011] Preferably, a hot oil circulation controller is used to adjust and control the temperature and circulation of the hot oil, comprising the following steps: Initializing the first temperature sensor and the first relay; Set the target temperature value; Continuously reading data from the first temperature sensor; According to the difference between the current temperature and the target temperature, it is decided whether to turn on the heater to adjust and control the temperature of the hot oil in the hot oil circulation pipe, and whether to turn on the first circulation pump to adjust and control the circulation of the hot oil in the hot oil circulation pipe.

[0012] Preferably, When the temperature is lower than the target temperature value of the hot oil, the heater is started and / or the speed of the first circulation pump is adjusted.

[0013] Preferably, When the temperature reaches or exceeds the target temperature value of the hot oil, the heater is stopped and / or the speed of the first circulation pump is adjusted.

[0014] Preferably, a liquid nitrogen circulation controller is used to adjust and control the temperature and circulation of liquid nitrogen, comprising the following steps: Initializing the second temperature sensor and the second relay; Set the target temperature value; Continuously reading data from the second temperature sensor; According to the difference between the current temperature and the target temperature, it is decided whether to start the cooling device to adjust and control the temperature of the liquid nitrogen in the liquid nitrogen circulation pipe, and whether to start the second circulation pump to adjust and control the circulation of the liquid nitrogen in the liquid nitrogen circulation pipe.

[0015] Preferably, When the temperature is higher than the target temperature value of the liquid nitrogen, the cooling device is started and / or the speed of the second circulation pump is adjusted.

[0016] Preferably, When the temperature reaches or is lower than the target temperature value of the liquid nitrogen, the cooling device is stopped and / or the speed of the second circulation pump is adjusted.

[0017] Preferably, The outer part of the current-carrying conductor in the bushing is made of aluminum, and the inner part is a hollow structure.

[0018] Preferably, The hot oil circulation pipe is an insulating pipe.

[0019] Preferably, The liquid nitrogen circulation pipe is also an insulated pipe.

[0020] In addition, the present invention also discloses a DC wall bushing test system under large temperature difference conditions, comprising: DC wall bushing, bushing flange, bushing end grading ring, current-carrying conductor in bushing, hot oil circulation pipe, hot oil circulation controller, liquid nitrogen circulation pipe, liquid nitrogen circulation controller, high voltage DC power supply, partial discharge measurement impedance, and DC partial discharge tester, Among them, when the DC wall bushing is handed over or offline, under the condition that the bushing end equalizing rings are provided at both ends of the DC wall bushing, The bushing flange in the middle of the DC wall bushing is connected to the first end of the partial discharge measurement impedance, and the second end of the partial discharge measurement impedance is grounded; The partial discharge measurement impedance is connected to the DC partial discharge tester; The current-carrying conductor in the bushing is inserted into the DC wall bushing, wherein both ends of the current-carrying conductor in the bushing extend out of the bushing end equalizing rings arranged at both ends of the DC wall bushing, so that both ends of the current-carrying conductor in the bushing are exposed to the outside; A hot oil circulation pipe and a liquid nitrogen circulation pipe are respectively passed through the two ends of the current-carrying conductor in the casing from the outside to the inside; wherein the current-carrying conductor in the casing on one side of the hot oil circulation pipe is connected to a high-voltage DC power supply.

[0021] Compared with the prior art, the present invention has the following advantages: The present invention essentially proposes a DC voltage test method that can simulate the actual large temperature difference working conditions of DC wall bushings on site. Compared with the existing technology, it is more in line with the actual on-site conditions in cold regions and is more conducive to the electrical insulation assessment of DC wall bushings in the field of ultra-high voltage DC transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0023] In the attached picture: Figure 1 is a schematic flow chart of a test method according to an embodiment of the present invention; Figure 2 is a flow chart of a test method according to another embodiment of the present invention; Figure 3 is a schematic structural diagram of a test device according to another embodiment of the present invention; The following are the descriptions of the reference numerals: 1 is a DC wall bushing, 2 is a bushing flange, 3 is a bushing end equalizing ring, 4 is a current-carrying conductor in the bushing, 5 is a hot oil circulation pipe, 6 is a hot oil circulation controller, 7 is a liquid nitrogen circulation pipe, 8 is a liquid nitrogen circulation controller, 9 is a high-voltage DC power supply, 10 is a partial discharge measurement impedance, and 11 is a DC partial discharge tester.

[0024] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0025] The following will refer to the attached Figures 1 to 3Specific embodiments of the present invention are described in more detail. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0026] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0027] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0028] In one embodiment, see Figure 1 The present invention discloses a DC wall bushing test method under large temperature difference conditions, wherein: When the DC wall bushing is handed over or offline, a hot oil circulation pipe is implanted into one side of the DC wall bushing, and the temperature of the hot oil is adjusted to simulate the working conditions of the indoor side of the DC wall bushing; A liquid nitrogen circulation pipe is further implanted into the other side of the DC wall bushing, and the working conditions of the outdoor side of the DC wall bushing are simulated by adjusting the temperature of the liquid nitrogen; Under different temperature combinations of hot oil temperature and liquid nitrogen temperature, DC voltage test and partial discharge measurement are carried out on the DC wall bushing.

[0029] Offline in the above embodiment refers to the temporary or permanent removal of the DC wall bushing from operation, and handover refers to the delivery of a new DC wall bushing to the converter station and before it is ready for installation. Therefore, the present invention essentially proposes a DC voltage test method that can simulate the actual large temperature difference working conditions of the DC wall bushing on site, which is more in line with the actual site conditions in cold areas than the prior art, and is more conducive to the electrical insulation assessment of DC wall bushings in the field of ultra-high voltage DC transmission.

[0030] For a better understanding, Figure 2As shown, in another embodiment, the DC wall bushing test method under large temperature difference conditions specifically includes the following steps: S100, when the DC wall bushing is handed over or taken offline, under the condition that bushing end grading rings are provided at both ends of the DC wall bushing, the bushing flange in the middle of the DC wall bushing is connected to the first end of the partial discharge measurement impedance, and the second end of the partial discharge measurement impedance is grounded; S200, connecting the partial discharge measurement impedance to the DC partial discharge tester; S300, inserting an inner current-carrying conductor into a DC wall bushing, wherein two ends of the inner current-carrying conductor extend out of the bushing end grading rings provided at two ends of the DC wall bushing; S400, a hot oil circulation pipe and a liquid nitrogen circulation pipe are respectively inserted from the outside to the inside at both ends of the current-carrying conductor in the casing; wherein the current-carrying conductor in the casing on one side of the hot oil circulation pipe is connected to a high-voltage DC power supply; S500, adjusting the temperature of the hot oil in the hot oil circulation pipe; S600, adjusting the temperature of liquid nitrogen in the liquid nitrogen circulation tube; S700, under different temperature combinations of hot oil temperature and liquid nitrogen temperature, uses high voltage DC power supply and DC partial discharge tester to conduct DC voltage test on DC wall bushing and perform partial discharge measurement.

[0031] In another embodiment, The hot oil circulation pipe is controlled by a hot oil circulation controller to adjust the temperature of the hot oil and the circulation of the hot oil in the hot oil circulation pipe.

[0032] In another embodiment, The liquid nitrogen circulation pipe is controlled by a liquid nitrogen circulation controller to adjust the temperature of the liquid nitrogen and the circulation of the liquid nitrogen in the liquid nitrogen circulation pipe.

[0033] In another embodiment, The hot oil circulation controller and the liquid nitrogen circulation controller both include a single chip microcomputer.

[0034] In another embodiment, a hot oil circulation controller is used to adjust and control the temperature and circulation of hot oil, including the following steps: Initializing the first temperature sensor and the first relay; Set the target temperature value; Continuously reading data from the first temperature sensor; According to the difference between the current temperature and the target temperature, it is decided whether to turn on the heater to adjust and control the temperature of the hot oil in the hot oil circulation pipe, and whether to turn on the first circulation pump to adjust and control the circulation of the hot oil in the hot oil circulation pipe.

[0035] In another embodiment, When the temperature is lower than the target temperature value of the hot oil, the heater is started and / or the speed of the first circulation pump is adjusted.

[0036] In another embodiment, When the temperature reaches or exceeds the target temperature value of the hot oil, the heater is stopped and / or the speed of the first circulation pump is adjusted.

[0037] In another embodiment, a liquid nitrogen circulation controller is used to adjust and control the temperature and circulation of liquid nitrogen, comprising the following steps: Initializing the second temperature sensor and the second relay; Set the target temperature value; Continuously reading data from the second temperature sensor; According to the difference between the current temperature and the target temperature, it is decided whether to start the cooling device to adjust and control the temperature of the liquid nitrogen in the liquid nitrogen circulation pipe, and whether to start the second circulation pump to adjust and control the circulation of the liquid nitrogen in the liquid nitrogen circulation pipe.

[0038] In another embodiment, When the temperature is higher than the target temperature value of the liquid nitrogen, the cooling device is started and / or the speed of the second circulation pump is adjusted.

[0039] In another embodiment, When the temperature reaches or is lower than the target temperature value of the liquid nitrogen, the cooling device is stopped and / or the speed of the second circulation pump is adjusted.

[0040] In another embodiment, The outer part of the current-carrying conductor in the bushing is made of aluminum, and the inner part is a hollow structure.

[0041] In another embodiment, The hot oil circulation pipe is an insulating pipe.

[0042] In another embodiment, The liquid nitrogen circulation pipe is also an insulated pipe.

[0043] In another embodiment, see Figure 3 The present invention also discloses a DC wall bushing test system under large temperature difference conditions, comprising: DC wall bushing 1, bushing flange 2, bushing end grading ring 3, current-carrying conductor in bushing 4, hot oil circulation pipe 5, hot oil circulation controller 6, liquid nitrogen circulation pipe 7, liquid nitrogen circulation controller 8, high-voltage DC power supply 9, partial discharge measurement impedance 10, and DC partial discharge tester 11, When the DC wall bushing 1 is handed over or offline, under the condition that the bushing end grading rings 3 are provided at both ends of the DC wall bushing 1, The bushing flange 2 in the middle of the DC wall bushing is connected to the first end of the partial discharge measurement impedance 10, and the second end of the partial discharge measurement impedance is grounded; The partial discharge measuring impedance is connected to the DC partial discharge tester; illustratively, the third end of the partial discharge measuring impedance is connected to the DC partial discharge tester 11; The current-carrying conductor 4 in the bushing is inserted into the DC wall bushing 1, wherein both ends of the current-carrying conductor 4 in the bushing extend out of the bushing end grading rings 3 arranged at both ends of the DC wall bushing, so that both ends of the current-carrying conductor 4 in the bushing are exposed to the outside; A hot oil circulation pipe 5 and a liquid nitrogen circulation pipe 7 are respectively passed through the two ends of the current-carrying conductor 4 in the casing from the outside to the inside; wherein the current-carrying conductor 4 in the casing on one side of the hot oil circulation pipe is connected to a high-voltage DC power supply 9.

[0044] In another embodiment, The hot oil circulation pipe 5 is controlled by the hot oil circulation controller 6 to adjust the temperature of the hot oil in the hot oil circulation pipe and the hot oil circulation.

[0045] In another embodiment, The liquid nitrogen circulation pipe 7 is controlled by the liquid nitrogen circulation controller 8 to adjust the temperature of the liquid nitrogen and the circulation of the liquid nitrogen in the liquid nitrogen circulation pipe.

[0046] In another embodiment, the system further comprises: A heater, a first temperature sensor, a first relay, and a first circulation pump connected to the hot oil circulation controller.

[0047] In another embodiment, the system further comprises: A cooling device, a second temperature sensor, a second relay, and a second circulation pump connected to the liquid nitrogen circulation controller.

[0048] In another embodiment, the system further comprises: The oil storage device provides oil to the hot oil circulation pipe.

[0049] In another embodiment, the system further comprises: The liquid nitrogen storage device provides liquid nitrogen to the liquid nitrogen circulation pipe.

[0050] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A DC wall bushing test method under large temperature difference conditions, wherein: When the DC wall bushing is handed over or offline, a hot oil circulation pipe is implanted into one side of the DC wall bushing, and the temperature of the hot oil is adjusted to simulate the working conditions of the indoor side of the DC wall bushing; A liquid nitrogen circulation pipe is further implanted into the other side of the DC wall bushing, and the working conditions of the outdoor side of the DC wall bushing are simulated by adjusting the temperature of the liquid nitrogen; Under different temperature combinations of hot oil temperature and liquid nitrogen temperature, DC voltage test and partial discharge measurement are carried out on the DC wall bushing.

2. The method according to claim 1, wherein: Preferably, The hot oil circulation pipe is controlled by a hot oil circulation controller to adjust the temperature of the hot oil and the circulation of the hot oil in the hot oil circulation pipe.

3. The method according to claim 1, wherein: The liquid nitrogen circulation pipe is controlled by a liquid nitrogen circulation controller to adjust the temperature of the liquid nitrogen and the circulation of the liquid nitrogen in the liquid nitrogen circulation pipe.

4. The method according to claim 1, wherein: The hot oil circulation controller and the liquid nitrogen circulation controller both include a single chip microcomputer.

5. The method according to claim 1, wherein: The outer part of the current-carrying conductor in the bushing is made of aluminum, and the inner part is a hollow structure.

6. The method according to claim 1, wherein: The hot oil circulation pipe is an insulating pipe.

7. The method according to claim 1, wherein: The liquid nitrogen circulation pipe is an insulated pipe.

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