Converter transformer valve side bushing long-term dc voltage insulation test equipment and method

Abstract

The application discloses a kind of converter transformer valve side bushing long-term DC voltage insulation test equipment and method, comprising: DC voltage generating device, output positive polarity or negative polarity DC voltage to each converter valve side bushing module;Signal sensor module, the current pulse signal at the DC voltage generating device and each converter valve side bushing module is measured;Monitoring module, the state of valve side bushing is determined based on the current pulse signal obtained.The application can simulate the actual operation condition of converter transformer valve side bushing, carry out long-term DC voltage withstand test under actual operation voltage condition, can provide reliable means for the insulation performance evaluation of converter valve side bushing, help to find potential insulation risk in advance, improve the safety and stability of its grid-connected operation, it has important significance for guaranteeing the safe operation of UHVDC transmission system and improving the self-controllable ability of key core equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage direct current transmission, and more particularly, to a long-term direct current voltage insulation test device and method for a valve-side bushing of a converter transformer. BACKGROUND

[0002] In a high-voltage direct current transmission system, the valve-side bushing of a converter transformer is long-term subjected to direct current voltage, and its insulation performance faces more severe and complex challenges. The existing standards such as GB / T 4109-2008 "AC voltage high-voltage bushings", IEC / IEEE 65700-19-03 Edition 1.0 2014-07 "Bushings for DC application" and IEC60137 Edition 7.0 2017-06 "Insulated bushings for alternating voltages above 1000V" are mainly aimed at bushing products in alternating current systems, and the type tests and individual tests specified by the standards are mainly short-time withstand voltage, dielectric loss, capacitance and partial discharge, etc. Although these tests can effectively verify the insulation level of the bushing in a short time, the test time is limited and the voltage working condition is single, which makes it difficult to truly reflect the insulation performance evolution process under long-term direct current voltage due to electric field distortion, material aging and partial discharge accumulation effect, especially in verifying the long-term impact of partial discharge on the insulation system. Therefore, the conventional factory test based on the standards cannot meet the technical requirements of the long-term operation reliability evaluation of the valve-side bushing of the converter transformer.

[0003] At present, the research on the insulation performance change of the valve-side bushing of the converter transformer under long-term direct current voltage is still in its infancy, and there is a lack of systematic test data and mature verification methods, and the relevant engineering experience and operation cases are also limited. In terms of simulation, monitoring and evaluation of the insulation behavior of the bushing under long-term direct current working condition, a scientific and systematic test method and platform have not been established, and there is still a significant gap in the technical system.

[0004] To address the aforementioned problems, this invention focuses on the insulation performance testing technology of valve-side bushings in converter transformers under long-term DC voltage. Through in-depth analysis of existing technologies, it proposes a bipolar voltage control method, a multi-channel partial discharge signal monitoring method, and a bushing discharge pulse signal identification method suitable for long-term DC voltage insulation testing of valve-side bushings. A system composition capable of simultaneously conducting long-term DC voltage insulation tests on two or more valve-side bushings is also proposed. This platform possesses continuous monitoring capabilities for partial discharge pulse signals, enabling continuous acquisition of the discharge characteristics of the bushing sample and other components of the high-voltage circuit during pressurization. It can dynamically acquire key insulation state parameters of the bushing at different operating stages, providing crucial data support for analyzing the evolution trend of bushing insulation performance and laying the foundation for constructing a long-term insulation performance testing and evaluation system oriented towards engineering applications.

[0005] Therefore, there is a need for a device and method for long-term DC voltage insulation testing of the valve-side bushing of a converter transformer. Summary of the Invention

[0006] This invention proposes a long-term DC voltage insulation test device and method for the valve-side bushing of a converter transformer, in order to solve the problem of how to conduct a long-term DC voltage insulation test on the valve-side bushing of a converter transformer.

[0007] To address the aforementioned problems, according to one aspect of the present invention, a long-term DC voltage insulation test device for converter transformer valve-side bushings is provided. The device comprises: a DC voltage generating device, a signal sensor module, a monitoring module, and at least two parallel converter transformer valve-side bushing modules; wherein...

[0008] The DC voltage generator is connected to each converter valve side bushing module and is used to output a positive or negative DC voltage to each converter valve side bushing module.

[0009] The signal sensor module is connected to the DC voltage generator and each converter valve side bushing module, respectively, and is used to measure the current pulse signal at the DC voltage generator and each converter valve side bushing module;

[0010] The monitoring module is connected to the signal sensor module and is used to determine the state of the valve-side bushing based on the acquired current pulse signal.

[0011] Preferably, each converter transformer valve-side bushing module includes: a protective resistor, a simulated grounding wall, a simulated outgoing line submodule, and a simulated oil tank; wherein, the two ends of the protective resistor are connected to the valve-side bushing and the DC voltage generator respectively, the simulated grounding wall is set in the middle of the valve-side bushing, and the simulated outgoing line module and the simulated oil tank are both set at the tail end of the valve-side bushing; the valve-side bushing is arranged at an angle to simulate the actual installation state.

[0012] Preferably, the simulated output submodule adopts a thin paper tube-small oil gap structure and an open pressure equalizing ball structure at the bottom.

[0013] Preferably, the signal sensor module includes:

[0014] A high-frequency sensor is installed at the lead wire of the capacitor divider in the DC voltage generator to measure the high-frequency current pulse signal at the lead wire of the capacitor divider in the DC voltage generator.

[0015] A high-frequency pulse current sensor is installed at the end screen of each valve-side bushing to measure the current pulse signal at the lead-out line of the corresponding valve-side bushing end screen.

[0016] Preferably, the signal sensor module further includes: an ultrasonic sensor, an ultra-high frequency sensor, and an ultraviolet imager; wherein,

[0017] The ultrasonic sensor is installed on the outer wall of the simulated oil tank of the converter valve side bushing module and is used to measure ultrasonic signals.

[0018] The ultra-high frequency sensor is installed in the space formed by the converter valve side bushing module and the DC voltage generator, and is used to measure the electromagnetic wave signal of space discharge.

[0019] The ultraviolet imager is used to acquire ultraviolet images during the experiment.

[0020] According to another aspect of the present invention, a test method is provided based on the long-term DC voltage insulation test equipment for the valve-side bushing of a converter transformer as described above, the method comprising:

[0021] A DC voltage generator is used to output a positive or negative DC voltage to each converter valve-side bushing module;

[0022] The current pulse signal at the DC voltage generator and each converter valve side bushing module is monitored using a signal sensor module;

[0023] The monitoring module determines the state of the valve-side bushing based on the acquired current pulse signal.

[0024] Preferably, the monitoring of current pulse signals at the DC voltage generator and each converter valve-side bushing module using a signal sensor module includes:

[0025] The high-frequency current pulse signal at the lead wire of the capacitor divider of the DC voltage generator is measured using a high-frequency sensor in the signal sensor module.

[0026] The current pulse signal at the lead-out line of the corresponding valve-side bushing end screen is measured using a high-frequency pulse current sensor.

[0027] Preferably, the method of determining the state of the valve-side bushing based on the acquired current pulse signal using a monitoring module includes:

[0028] Based on the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission, the current pulse signal is sequentially screened to select the bushing body discharge pulse that meets the conditions.

[0029] The state of the valve-side bushing is determined based on the discharge pulse of the bushing body.

[0030] Preferably, the method further includes:

[0031] Square wave pulse correction is performed on different positions of the bushing test sample and the DC voltage generator to obtain the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission.

[0032] Preferably, determining the state of the valve-side bushing based on the discharge pulse of the bushing body includes:

[0033] Based on the discharge pulse of the bushing body, it is determined whether there is a preset number of pulses greater than 2000pc within a preset time period that exceeds a preset number threshold. If so, the state of the valve-side bushing is determined to be abnormal; if not, the state of the valve-side bushing is determined to be normal.

[0034] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the steps of a test method based on a long-term DC voltage insulation test device for a converter transformer valve-side bushing.

[0035] According to another aspect of the present invention, the present invention provides an electronic device, comprising:

[0036] The aforementioned computer-readable storage medium; and

[0037] One or more processors for executing a program in the computer-readable storage medium.

[0038] This invention provides a long-term DC voltage insulation test device and method for converter transformer valve-side bushings, comprising: a DC voltage generator that outputs a positive or negative DC voltage to each converter transformer valve-side bushing module; a signal sensor module that measures the current pulse signals at the DC voltage generator and each converter transformer valve-side bushing module; and a monitoring module that determines the state of the valve-side bushing based on the acquired current pulse signals. This invention can simulate the actual operating conditions of converter transformer valve-side bushings and conduct long-term DC withstand voltage tests under actual operating voltage conditions. It provides a reliable means for evaluating the insulation performance of converter transformer valve-side bushings, helps to identify potential insulation risks in advance, and improves the safety and stability of grid-connected operation. This is of great significance for ensuring the safe operation of ultra-high voltage direct current transmission systems and enhancing the independent controllability of key core equipment. Attached Figure Description

[0039] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0040] Figure 1 This is a schematic diagram of the structure of a long-term DC voltage insulation test device 100 for a converter transformer valve-side bushing according to an embodiment of the present invention;

[0041] Figure 2 This is an example diagram of a long-term DC voltage insulation test device for the valve-side bushing of a converter transformer according to an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the valve-side sleeve state according to an embodiment of the present invention;

[0043] Figure 4 This is a flowchart of a test method 400 based on a long-term DC voltage insulation test device for a converter transformer valve-side bushing according to an embodiment of the present invention;

[0044] Figure 5 This is a diagram illustrating the voltage application process for a long-term DC voltage test on the valve-side bushing according to an embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram of the bushing simulated discharge signal transmission ratio calibration position according to an embodiment of the present invention;

[0046] Figure 7 This is a schematic diagram of the power supply simulated discharge signal transmission ratio calibration position according to an embodiment of the present invention;

[0047] Figure 8 This is a flowchart of the internal discharge diagnosis process of the valve-side bushing according to an embodiment of the present invention. Detailed Implementation

[0048] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0049] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0050] Figure 1 This is a schematic diagram of the structure of a long-term DC voltage insulation test device 100 for a converter transformer valve-side bushing according to an embodiment of the present invention. Figure 1 As shown, the long-term DC voltage insulation test equipment for converter transformer valve-side bushings provided in this embodiment of the invention can simulate the actual operating conditions of converter transformer valve-side bushings and conduct long-term DC withstand voltage tests under actual operating voltage conditions. This provides a reliable means for evaluating the insulation performance of converter transformer valve-side bushings, helps to identify potential insulation risks in advance, and improves the safety and stability of grid-connected operation. It is of great significance for ensuring the safe operation of ultra-high voltage direct current transmission systems and enhancing the independent controllability of key core equipment. The long-term DC voltage insulation test equipment 100 for converter transformer valve-side bushings provided in this embodiment of the invention includes: a DC voltage generating device 101, a signal sensor module 102, a monitoring module 103, and at least two parallel converter transformer valve-side bushing modules 104.

[0051] Preferably, the DC voltage generator 101 is connected to each converter valve side bushing module 104 and is used to output a positive or negative DC voltage to each converter valve side bushing module.

[0052] Preferably, the signal sensor module 102 is connected to the DC voltage generator and each converter valve side bushing module, respectively, and is used to measure the current pulse signal at the DC voltage generator and each converter valve side bushing module.

[0053] Preferably, the monitoring module 103 is connected to the signal sensor module and is used to determine the state of the valve-side sleeve based on the acquired current pulse signal.

[0054] Preferably, each converter transformer valve-side bushing module 104 includes: a protective resistor, a simulated grounding wall, a simulated outgoing line submodule, and a simulated oil tank; wherein, the two ends of the protective resistor are connected to the valve-side bushing and the DC voltage generator respectively, the simulated grounding wall is set in the middle of the valve-side bushing, and the simulated outgoing line module and the simulated oil tank are both set at the tail end of the valve-side bushing; the valve-side bushing is arranged at an angle to simulate the actual installation state.

[0055] Preferably, the simulated output submodule adopts a thin paper tube-small oil gap structure and an open pressure equalizing ball structure at the bottom.

[0056] Preferably, the signal sensor module includes:

[0057] A high-frequency sensor is installed at the lead wire of the capacitor divider in the DC voltage generator to measure the high-frequency current pulse signal at the lead wire of the capacitor divider in the DC voltage generator.

[0058] A high-frequency pulse current sensor is installed at the end screen of each valve-side bushing to measure the current pulse signal at the lead-out line of the corresponding valve-side bushing end screen.

[0059] Preferably, the signal sensor module further includes: an ultrasonic sensor, an ultra-high frequency sensor, and an ultraviolet imager; wherein,

[0060] The ultrasonic sensor is installed on the outer wall of the simulated oil tank of the converter valve side bushing module and is used to measure ultrasonic signals.

[0061] The ultra-high frequency sensor is installed in the space formed by the converter valve side bushing module and the DC voltage generator, and is used to measure the electromagnetic wave signal of space discharge.

[0062] The ultraviolet imager is used to acquire ultraviolet images during the experiment.

[0063] In this invention, the test equipment includes: a high-voltage circuit arrangement capable of simultaneously conducting long-term DC voltage insulation tests on multiple converter transformer valve-side bushings; a DC voltage generator capable of stably outputting long-term DC voltage; a simulated wall device simulating the valve hall structure in engineering applications; a test outgoing line device structure simulating the electric field distribution structure at the oil end of the valve-side bushing; and a monitoring module with multi-channel partial discharge pulse signal acquisition and analysis capabilities. This enables multi-channel partial discharge monitoring and bipolar voltage testing of the converter transformer valve-side bushings during long-term DC voltage insulation tests, as well as identification of bushing discharge pulse signals.

[0064] Specifically, in combination Figure 2As shown, in the arrangement of the high-voltage circuit for the long-term DC voltage insulation test, the high-voltage circuit adopts a parallel arrangement of multiple (two or more) converter transformer valve-side bushings, wherein the valve-side bushings are connected to the DC voltage generating device via protective resistors. Combined with... Figure 3 As shown, the valve-side bushing is arranged at an angle to simulate the actual installation state. A simulated grounding wall is arranged in the middle of the valve-side bushing, simulating the actual installation state, and a simulated outgoing line device and oil tank structure are arranged at the tail end of the valve-side bushing, simulating the actual installation state. Among them, the test outgoing line device adopts a thin paper tube-small oil gap structure similar to the internal structure of the actual converter transformer, and the bottom adopts an open pressure equalizing ball structure.

[0065] In this invention, during the long-term DC voltage test of the valve-side bushing, a high-frequency sensor installed at the lead of the capacitor divider of the DC voltage generator is used to measure the high-frequency current pulse signal at the lead of the capacitor divider of the DC voltage generator; a high-frequency pulse current sensor installed at the end screen of each valve-side bushing is used to measure the current pulse signal at the corresponding end screen lead of the valve-side bushing. The monitoring module then determines the state of the valve-side bushing based on the acquired current pulse signals.

[0066] Furthermore, during the long-term DC voltage test of the valve-side bushing, this invention can also employ ultra-high frequency sensors, a space ultra-high voltage frequency partial discharge instrument, and an ultraviolet imager to continuously monitor and assist in the analysis of the bushing and the external equalizing ring, umbrella skirt corona, and spatial interference signals of the DC equipment. Specifically, to continuously monitor all discharge pulse signals of the bushing during the test, a high-frequency coil is arranged at the bushing's end screen lead to detect impedance; an ultrasonic sensor is arranged on the outer wall of the oil tank; ultra-high frequency sensors are arranged at multiple points in space; and a high-frequency coil is arranged at the lower end of the DC voltage generator's RC divider to detect impedance. Multiple monitoring methods are used to comprehensively judge, analyze, and statistically analyze the internal discharge pulse signals of the bushing. During continuous recording, relevant operations are performed according to the partial discharge pulse evaluation process. The test plan is shown in Table 1.

[0067] Table 1 Test Plan

[0068]

[0069] Figure 4 This is a flowchart of a test method 400 based on a long-term DC voltage insulation test device for a converter transformer valve-side bushing according to an embodiment of the present invention. Figure 4 As shown, the test method 400 based on the long-term DC voltage insulation test equipment for converter transformer valve side bushings provided by the embodiment of the present invention starts from step 401. In step 401, a DC voltage generator outputs a positive or negative DC voltage to each converter transformer valve side bushing module.

[0070] In step 402, the current pulse signal at the DC voltage generator and each converter valve side bushing module is monitored using a signal sensor module.

[0071] Preferably, the monitoring of current pulse signals at the DC voltage generator and each converter valve-side bushing module using a signal sensor module includes:

[0072] The high-frequency current pulse signal at the lead wire of the capacitor divider of the DC voltage generator is measured using a high-frequency sensor in the signal sensor module.

[0073] The current pulse signal at the lead-out line of the corresponding valve-side bushing end screen is measured using a high-frequency pulse current sensor.

[0074] In this invention, based on Figure 1 The equipment shown is used for long-term DC voltage insulation testing of the valve-side bushings of converter transformers. A DC voltage generator outputs a positive or negative DC voltage to each converter transformer valve-side bushing module; a high-frequency sensor in the signal sensor module measures the high-frequency current pulse signal at the lead-out of the capacitor divider of the DC voltage generator; and a high-frequency pulse current sensor measures the current pulse signal at the lead-out of the corresponding valve-side bushing's end screen.

[0075] In this invention, a long-term DC voltage insulation test and bipolar DC voltage assessment are also required. For example... Figure 4 As shown, taking the ±800kV valve-side bushing long-term DC voltage test as an example, the test includes two components: positive and negative polarity. For each polarity, the test is divided into three stages. The DC voltage is applied starting at +700kV (the DC voltage component under rated operating conditions) and maintained for more than 30 days. Subsequently, the voltage is gradually increased to more than 1.25 times the rated DC voltage and maintained for more than 15 days. SF6 composition, oil chromatography, and dielectric loss capacitance are compared before and after the test. A long-term DC voltage insulation test is conducted once for both positive and negative polarities, during which partial discharge pulse waveforms are continuously recorded. The time parameters for the above long-term DC voltage insulation test are determined based on the simulation calculation results of the internal electric field stabilization time of the ±800kV converter transformer valve-side bushing.

[0076] In step 403, the monitoring module determines the state of the valve-side bushing based on the acquired current pulse signal.

[0077] Preferably, the method of determining the state of the valve-side bushing based on the acquired current pulse signal using a monitoring module includes:

[0078] Based on the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission, the current pulse signal is sequentially screened to select the bushing body discharge pulse that meets the conditions.

[0079] The state of the valve-side bushing is determined based on the discharge pulse of the bushing body.

[0080] Preferably, the method further includes:

[0081] Square wave pulse correction is performed on different positions of the bushing test sample and the DC voltage generator to obtain the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission.

[0082] Preferably, determining the state of the valve-side bushing based on the discharge pulse of the bushing body includes:

[0083] Based on the discharge pulse of the bushing body, it is determined whether there is a preset number of pulses greater than 2000pc within a preset time period that exceeds a preset number threshold. If so, the state of the valve-side bushing is determined to be abnormal; if not, the state of the valve-side bushing is determined to be normal.

[0084] In this invention, the evaluation of partial discharge pulse signals requires first determining whether the discharge originates from the test bushing itself. Different partial discharge pulse signal measurement channels have specific transmission ratio relationships, and these relationships are significantly correlated with bushing position, discharge signal location, etc. Therefore, accurate calibration is necessary before the experiment. Signal transmission ratio tests simulating actual discharge signal characteristics at different locations are required to determine the transmission ratio for different preset high voltage to the final screen square wave verification, preset DC equipment discharge pulse transmission ratio, preset spatial discharge pulse transmission ratio, preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission order. For example... Figure 6 As shown, the square wave is applied at point A, the high-voltage end of the bushing; when the square wave is connected to B1, the signal is received from the bushing flange; when the square wave is connected to B2, the signal is received at the tail end of the high-frequency CT coil; when the square wave is connected to B3, the signal is received at the tail end of the impedance measurement. Figure 7 As shown, the first end of the square wave is connected to point A, which is the high-voltage end of the DC generator; the last end of the square wave is connected to point B, which is the end of the measured impedance receiving signal.

[0085] In this invention, taking the long-term DC voltage insulation test of two ±800kV converter transformer valve side bushings as an example, when square wave pulse correction is performed on the bushing test specimens and DC equipment at different positions, the magnitude and polarity relationship of the discharge quantity among the two bushing test specimens (referred to as bushing #1 and bushing #2) and the DC equipment is shown in Table 2 below. For example, the correction position is the high voltage of bushing #1 to the end screen, and the transmission ratio of bushing #1 to bushing #2 is 16-25 times, with opposite polarity. This means that when a square wave correction signal is applied to the high voltage end of bushing #1, the discharge quantity detected by bushing #1 is 16-25 times that detected by bushing #2, and the two have opposite polarities. Other transmission ratios all represent this meaning.

[0086] Table 2 Transmission Ratio and Polarity Table

[0087]

[0088] In this invention, given the relationship between the discharge signal transmission ratio and polarity, the partial discharge pulse evaluation process is as follows: Figure 8 As shown, specifically, a set of pulsed current partial discharge data was detected using a partial discharge instrument, containing three signals representing the partial discharge data corresponding to bushing #1, bushing #2, and the DC voltage generator, respectively. First, all pulsed current partial discharge data that meet the transmission ratio of the high voltage to the final screen square wave are screened out, which are the possible discharge pulses in the bushing body. Since the transmission ratio of pulse signals such as space discharge may overlap with the above transmission ratio, the above pulse discharge data need to be further eliminated according to the transmission ratio of space discharge, DC equipment discharge, and high voltage tip foreign object discharge. Finally, the remaining data are the discharge of the bushing body (space discharge is monitored by ultraviolet detection and other means, and obvious discharge photons can be detected in space and simulated walls, etc. At this time, the magnitude polarity relationship of the discharge signal of each channel is the space discharge pulse transmission ratio; foreign objects are placed at the high voltage tip of the bushing to simulate foreign object discharge, and the magnitude polarity relationship of the discharge signal of each channel is the high voltage tip foreign object discharge transmission ratio).

[0089] In this invention, during the initial DC voltage test of the bushing model, an increasing trend in the discharge pulse characteristics was observed. After 30 days of voltage application, the number of pulses exceeding 1000 pC began to increase rapidly until flashover discharge occurred. Therefore, during long-term DC testing, it is necessary to continuously record the cumulative discharge pulse count over time. Thus, in this invention, in conjunction with DC bushing test standards, for a given bushing body discharge pulse, if the number of pulses exceeding 2000 pC within any 30-minute period is greater than 10, the valve-side bushing is determined to be in an abnormal state; conversely, if the number of pulses exceeding 2000 pC within any 30-minute period is less than or equal to 10, the valve-side bushing is determined to be in a normal state.

[0090] In this invention, for the parallel test of multiple tubes, the principle is the same as the above principle. It is only necessary to calculate the discharge magnitude and polarity relationship between each pair or between three or even multiple devices during the square wave correction stage, so as to serve as the basis for discharge troubleshooting.

[0091] Combination Figure 8 As shown, when there are two bushing samples and one DC power supply, three measurement channels CH1, CH2, and CH3 are required. Through calibration, the relationships between the discharge magnitudes and discharge polarities between CH1 and CH2, CH1 and CH3, and CH2 and CH3 are obtained when simulated discharge signals are applied to the two bushing samples and the DC power supply, respectively. This information serves as a method for subsequent discharge power source determination. For multiple bushing samples, a simulated discharge signal is first applied to each bushing sample and the DC power supply. Taking three bushing samples and one DC power supply as an example: four measurement channels CH1, CH2, CH3, and CH4 are required. Through calibration, the relationships between the discharge magnitudes and discharge polarities between CH1 and CH2, CH1 and CH3, CH1 and CH4, CH2 and CH3, CH2 and CH4, and CH3 and CH4 are obtained when simulated discharge signals are applied to the three bushing samples and the DC power supply, respectively. This information serves as a method for subsequent discharge power source determination. When using the method of this invention on more samples, it is only necessary to set up a discharge measurement channel for each sample and DC equipment to obtain the relationship between the discharge quantity and discharge polarity of each channel when simulating discharge at different positions. The most important thing is to ensure that there is a quantitative comparison between any two channels, so as to serve as the basis for subsequent discharge position determination.

[0092] Following the above evaluation process, the partial discharge pulse signals monitored during the long-term test of the converter transformer valve-side bushing can be used to evaluate and determine the bushing status and perform relevant operations. Simultaneously, the partial discharge pulse signal data recorded using the above method can provide a reliable theoretical basis for the subsequent long-term DC operation of the ±800kV converter transformer valve-side bushing.

[0093] This invention overcomes the limitations of existing standard test times being short and operating condition simulations being insufficient. It can effectively support the verification of insulation performance of high-end converter transformer valve-side bushings under long-term DC voltage, promote the development of bushing test methods from short-time to long-term and from static to operating condition-based, fill the key technological gap in this field, and provide strong technical support for the safe and stable operation of bushings.

[0094] In this invention, taking the ±800kV converter transformer valve-side bushing test as an example, the test equipment and method of this invention are used to obtain key insulation performance parameters such as SF6 composition of the two bushings, oil chromatography of the outgoing line insulating oil, bushing dielectric loss and capacitance, and DC partial discharge pulse signal before, during, and after the long-term DC energized test. Based on these parameters, the insulation performance of the ±800kV valve-side bushing during the long-term DC test is diagnosed.

[0095] (1) Analysis results of discharge pulse signals during long-term DC voltage test

[0096] During the experiment, the ambient background discharge pulse amplitude was within 200 pC, therefore the lower limit of the discharge pulse amplitude automatically acquired by the system was set to 500 pC. When any one of the three channels CH1, CH2, and CH3 captured a discharge signal exceeding 500 pC, an induced signal would be generated because the two bushings were connected to the DC power supply equipment via a circuit. The DC partial discharge monitoring system would simultaneously save the discharge pulse data of all three channels at that moment. Since the pulse transmission ratio under a typical discharge signal was obtained before the experiment, the source of the actual discharge signal could be analyzed by comparing and analyzing the waveform differences obtained from the three channels. During the long-term experiment lasting 100 days, a total of 944,518 partial discharge pulse data points were captured. After excluding interference pulse signals caused by operational factors such as voltage boosting and bucking, more than 400,000 interference signals from the test system and space were identified. The discharge interference during the experiment mainly came from foreign object discharge in the bushing equalizing ring, high-voltage tip discharge, DC equipment discharge, and space discharge. The statistical results of the discharge pulse signals are shown in Table 3.

[0097] Table 3 Statistical results of partial discharge pulse signals during long-term testing

[0098]

[0099] Based on the calibration results of the transmission ratio of the bushing's high-voltage end to the square wave pulse signal of the final screen, the possible discharge pulse signals of the bushing are extracted from the valid data. By eliminating DC equipment discharge, spatial interference discharge, and discharge from foreign objects in the equalizing ball, the number of partial discharge pulses in the bushing body is determined. In the long-term DC voltage test with positive and negative polarities, according to the statistical results, the number of partial discharges in the bushing body is 0.

[0100] Compared to the traditional test methods specified in IEC / IEEE 65700-19-03 and GB / T 4109-2008 standards, the test system and method proposed in this invention introduce a multi-parameter collaborative monitoring and analysis mechanism, comprehensively examining key indicators such as bushing dielectric loss factor and capacitance, SF6 gas composition at the gas end, oil chromatography analysis results of the outgoing line device, and discharge characteristic data. In a 100-day DC withstand voltage test, this method was applied to systematically evaluate two ±800kV valve-side bushings. The test results showed that the insulation performance of both bushings remained good throughout the loading period, and no discharge phenomena caused by internal insulation deterioration occurred. This provides a new technical means and effective support for verifying the electrical stability of this type of bushing in actual long-term operation.

[0101] The method of this invention is also applicable to bushings with other rated voltage levels (such as ±500kV, ±600kV, ±1100kV, etc.). Therefore, the DC withstand voltage level can be adjusted proportionally according to the rated voltage level of the bushing being tested, and is not limited to the ±800kV level.

[0102] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the steps of a test method based on a long-term DC voltage insulation test device for a converter transformer valve-side bushing.

[0103] According to another aspect of the present invention, the present invention provides an electronic device, comprising:

[0104] The aforementioned computer-readable storage medium; and

[0105] One or more processors for executing a program in the computer-readable storage medium.

[0106] The present invention has been described with reference to a few embodiments. However, it will be apparent to those skilled in the art that other embodiments besides those disclosed above fall equivalently within the scope of the present invention.

[0107] Generally, all terms used in this invention are interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed unless explicitly stated otherwise.

[0108] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0109] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0110] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0111] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A long-term DC voltage insulation test device for the valve-side bushing of a converter transformer, characterized in that, The equipment includes: a DC voltage generator, a signal sensor module, a monitoring module, and at least two parallel converter transformer valve-side bushing modules; wherein, The DC voltage generator is connected to each converter valve side bushing module and is used to output a positive or negative DC voltage to each converter valve side bushing module. The signal sensor module is connected to the DC voltage generator and each converter valve side bushing module, respectively, and is used to measure the current pulse signal at the DC voltage generator and each converter valve side bushing module; The monitoring module is connected to the signal sensor module and is used to determine the state of the valve-side bushing based on the acquired current pulse signal. Each converter transformer valve-side bushing module includes: a protective resistor, a simulated grounding wall, a simulated outgoing line submodule, and a simulated oil tank; the two ends of the protective resistor are connected to the valve-side bushing and the DC voltage generator, respectively, and the simulated grounding wall is located in the middle of the valve-side bushing; The signal sensor module includes: A high-frequency sensor is installed at the lead wire of the capacitor divider in the DC voltage generator to measure the high-frequency current pulse signal at the lead wire of the capacitor divider in the DC voltage generator. A high-frequency pulse current sensor is installed at the end screen of each valve-side bushing to measure the current pulse signal at the lead-out line of the corresponding valve-side bushing end screen. The monitoring module determines the state of the valve-side bushing based on the acquired current pulse signal, including: Based on the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission, the current pulse signal is sequentially screened to select the bushing body discharge pulse that meets the conditions. The state of the valve-side bushing is determined based on the discharge pulse of the bushing body. Among them, square wave pulse correction is performed on different positions of the bushing test sample and the DC voltage generator to obtain the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission.

2. The device according to claim 1, characterized in that, Both the simulated output submodule and the simulated oil tank are located at the tail end of the valve-side bushing; the valve-side bushing is arranged at an angle to simulate the actual installation state.

3. The device according to claim 2, characterized in that, The simulated output submodule adopts a thin paper tube-small oil gap structure and an open pressure equalizing ball structure at the bottom.

4. The device according to claim 1, characterized in that, The signal sensor module further includes: an ultrasonic sensor, an ultra-high frequency sensor, and an ultraviolet imager; wherein, The ultrasonic sensor is installed on the outer wall of the simulated oil tank of the converter valve side bushing module and is used to measure ultrasonic signals. The ultra-high frequency sensor is installed in the space formed by the converter valve side bushing module and the DC voltage generator, and is used to measure the electromagnetic wave signal of space discharge. The ultraviolet imager is used to acquire ultraviolet images during the experiment.

5. A test method for a long-term DC voltage insulation test device for the valve-side bushing of a converter transformer based on any one of claims 1-4, characterized in that, The method includes: A DC voltage generator is used to output a positive or negative DC voltage to each converter valve-side bushing module; The current pulse signal at the DC voltage generator and each converter valve side bushing module is monitored using a signal sensor module; The monitoring module determines the state of the valve-side bushing based on the acquired current pulse signal; The monitoring of current pulse signals at the DC voltage generator and each converter valve-side bushing module is performed using a signal sensor module, including: The high-frequency current pulse signal at the lead wire of the capacitor divider of the DC voltage generator is measured using a high-frequency sensor in the signal sensor module. The current pulse signal at the lead-out line of the corresponding valve-side bushing end screen is measured using a high-frequency pulse current sensor. The process of determining the state of the valve-side bushing using a monitoring module based on acquired current pulse signals includes: Based on the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission, the current pulse signal is sequentially screened to select the bushing body discharge pulse that meets the conditions. The state of the valve-side bushing is determined based on the discharge pulse of the bushing body. The method further includes: Square wave pulse correction is performed on different positions of the bushing test sample and the DC voltage generator to obtain the preset high voltage to the end screen square wave verification transmission ratio, the preset DC equipment discharge pulse transmission ratio, the preset space discharge pulse transmission ratio, the preset high voltage tip foreign object discharge pulse transmission ratio, and the polarity corresponding to each transmission.

6. The method according to claim 5, characterized in that, Determining the state of the valve-side bushing based on the discharge pulse of the bushing body includes: Based on the discharge pulse of the bushing body, it is determined whether there is a preset number of pulses greater than 2000pc within a preset time period that exceeds a preset number threshold. If so, the state of the valve-side bushing is determined to be abnormal; if not, the state of the valve-side bushing is determined to be normal.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 5-6.

8. An electronic device, characterized in that, include: The computer-readable storage medium as described in claim 7; as well as One or more processors for executing a program in the computer-readable storage medium.

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