Submarine cable AC voltage withstand test system

Abstract

The utility model relates to a submarine cable AC voltage withstand test system. The system comprises a power supply, an excitation transformer, a first shunt reactor combination, a second shunt reactor combination and a voltage divider. The power supply is connected with the exciting transformer, one end of the exciting transformer is connected with the input end of the first shunt reactor combination, and the other end of the exciting transformer is grounded; the output end of the first shunt reactor combination is respectively connected with one end of the second shunt reactor combination, one end of the voltage divider and one end of a submarine cable to be tested; the other end of the second shunt reactor combination, the other end of the voltage divider and the other end of the submarine cable to be tested are all grounded. By adopting the system, the implementation difficulty of the submarine cable AC voltage withstand test can be reduced.

Description

Technical Field

[0001] The present application relates to the field of power grid technology, and in particular to an AC withstand voltage test system for submarine cables. Background Art

[0002] In the field of power grids, in order to detect the insulation performance of submarine cables, it is crucial to conduct AC withstand voltage tests on submarine cables.

[0003] Traditionally, when conducting AC withstand voltage tests on submarine cables, a variable frequency series resonant withstand voltage method is generally used. However, submarine cables are usually longer and have a larger capacity, which requires a larger current. This makes the implementation of AC withstand voltage tests on submarine cables more difficult. Utility Model Content

[0004] Based on this, it is necessary to provide a submarine cable AC withstand voltage test system that can reduce the difficulty of implementing the submarine cable AC withstand voltage test.

[0005] The present application provides a submarine cable AC withstand voltage test system, comprising: a power supply, an excitation transformer, a first shunt reactor combination, a second shunt reactor combination, and a voltage divider;

[0006] The power supply is connected to the excitation transformer, one end of the excitation transformer is connected to the input end of the first shunt reactor assembly, and the other end of the excitation transformer is grounded; the output end of the first shunt reactor assembly is respectively connected to one end of the second shunt reactor assembly, one end of the voltage divider, and one end of the submarine cable to be tested; the other end of the second shunt reactor assembly, the other end of the voltage divider, and the other end of the submarine cable to be tested are all grounded.

[0007] In one embodiment, the reactor in the first shunt reactor combination is the same as the reactor in the second shunt reactor combination;

[0008] The reactor includes an oil-immersed reactor.

[0009] In one embodiment, the first parallel reactor combination includes one reactor, and the second parallel reactor combination includes at least two reactors.

[0010] In one embodiment, the system further comprises: a first ammeter and a plurality of second ammeters;

[0011] One end of the first ammeter is connected to the other end of the excitation transformer, one end of each second ammeter is correspondingly connected to one end of a reactor in the second shunt reactor combination, and the other end of the first ammeter and the other end of each second ammeter are both grounded.

[0012] In one embodiment, the voltage divider includes a plurality of capacitors connected in series.

[0013] In one embodiment, the voltage divider further includes a voltmeter;

[0014] Two ends of the voltmeter are respectively connected to two ends of one capacitor among the multiple capacitors connected in series.

[0015] In one embodiment, the excitation transformer is a variable frequency excitation transformer.

[0016] In one embodiment, the power source is an AC power source.

[0017] In one embodiment, the inductance of the excitation transformer is in the mH level, and the inductance of the reactor in the first parallel reactor combination and the reactor in the second parallel reactor combination are both in the H level.

[0018] In one embodiment, the test frequency of the system is 20 Hz-300 Hz.

[0019] The above-mentioned submarine cable AC withstand voltage test system replaces the series inductor in the circuit with a hybrid inductor, so that the current on the submarine cable under test is shunted, thereby reducing the current passing through the power supply and the capacity required by the power supply side. This is conducive to meeting the capacity requirements of the submarine cable under test and thus reducing the difficulty of implementing the submarine cable AC withstand voltage test. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is a schematic diagram of an RLC series circuit in one embodiment;

[0023] Figure 2 Schematic diagram of a variable frequency series resonant withstand voltage test circuit in one embodiment;

[0024] Figure 3 Schematic diagram of a submarine cable AC withstand voltage test system according to one embodiment;

[0025] Figure 4 A schematic diagram of an AC withstand voltage test system for submarine cables according to another embodiment;

[0026] Figure 5 Schematic diagram of a submarine cable AC withstand voltage test system in yet another embodiment. DETAILED DESCRIPTION

[0027] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0029] It will be understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this application. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0030] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0031] It is understood that “at least one” refers to one or more, “a plurality” refers to two or more, and “at least a portion of an element” refers to a portion or all of an element.

[0032] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0033] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0034] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0035] The submarine cable AC withstand voltage test system involved in this application is based on the principle of RLC (Resistance Inductance Capacitance) series circuit, such as Figure 1 As shown. In this RLC series circuit:

[0036] is the voltage across the circuit, is the circuit current, R is the circuit resistance, jωL is the circuit inductive reactance, is the capacitive reactance of the circuit. The impedance in the circuit is: The power supply voltage is:

[0037] Since ω=2πf, when the frequency f in the circuit changes, the inductive reactance and capacitive reactance will also change, and the working state of the circuit will also change with the frequency. When the circuit resonates, That is, Z=R, and the loop frequency is

[0038] At this time, the voltage across the inductor And the voltage across the capacitor They are: as well as

[0039] In the above formula, Q is the quality factor of the circuit, which can generally range from tens to hundreds. As can be seen from the formula, when the RLC circuit is in the resonant state, the voltage across the inductor and capacitor is Q times the power supply voltage.

[0040] The submarine cable AC withstand voltage test system involved in this application is based on Figure 2 The circuit shown in FIG. 1 is obtained. In this circuit, the excitation transformer is powered by AC (Alternating Current) voltage, U is the output voltage of the excitation transformer, and I TX Refers to the output current of the excitation transformer, IC is the submarine cable current, I1 refers to the current of the first reactor, I2 refers to the current of the second reactor, and I n Refers to the current of the nth reactor, I (3-(n-1)) It refers to the current of the 3rd to n-1th reactors. Assuming the inductance of a single reactor is L1 and the capacitance of the submarine cable to be measured is C1, then according to the characteristics of the RLC series circuit, when the loop resonates, the loop frequency is At this time, the voltage across the reactor and the test piece is Q times the output voltage of the excitation transformer.

[0041] In an exemplary embodiment, Figure 3 As shown, the present application provides a submarine cable AC withstand voltage test system, which includes: a power supply 301, an excitation transformer 302, a first shunt reactor assembly 303, a second shunt reactor assembly 304, and a voltage divider 305; the power supply 301 is connected to the excitation transformer 302, one end of the excitation transformer 302 is connected to the input end of the first shunt reactor assembly 303, and the other end of the excitation transformer 302 is grounded; the output end of the first shunt reactor assembly 303 is respectively connected to one end of the second shunt reactor assembly 304, one end of the voltage divider 305, and one end of a submarine cable to be tested 306; the other end of the second shunt reactor assembly 304, the other end of the voltage divider 305, and the other end of the submarine cable to be tested 306 are all grounded.

[0042] like Figure 3 As shown, U is the output voltage of the excitation transformer, I TY Refers to the output current of the excitation transformer, I C is the submarine cable current, I (m+2-(n-1)) refers to the current of the reactors from m+2 to n-1, I1 refers to the current of the first reactor, I m Refers to the current of the mth reactor, I n Refers to the current of the nth reactor, I (2-(m-1)) Refers to the current of the 2nd to m-1th reactors, I m+1 It refers to the current of the m+1th reactor.

[0043] The power supply 301 is generally a power supply module commonly used in the market for AC withstand voltage testing of submarine cables, such as an AC power supply, a variable frequency power supply, and the like.

[0044] The excitation transformer 302 is generally an excitation transformer commonly used in the market for submarine cable AC withstand voltage tests, such as a variable frequency excitation transformer.

[0045] The first shunt reactor combination 303 is a shunt reactor combination connected in series with the submarine cable during the AC withstand voltage test of the submarine cable. It should be noted that the reactors in the first shunt reactor combination 303 are connected in parallel with each other.

[0046] The second shunt reactor combination 304 is a shunt reactor combination connected in parallel with the submarine cable during the AC withstand voltage test of the submarine cable. It should be noted that the reactors in the second shunt reactor combination 304 are connected in parallel with each other.

[0047] It should be noted that the reactors in the first shunt reactor combination 303 and the reactors in the second shunt reactor combination 304 are both reactors commonly used in the market for AC withstand voltage tests of submarine cables, such as oil-immersed reactors.

[0048] The voltage divider 305 is a voltage divider commonly used in the market for AC withstand voltage tests of submarine cables, such as a capacitive voltage divider.

[0049] Among them, the submarine cable 306 to be tested (i.e. Figure 3 C1) in the figure refers to a cable used for an AC withstand voltage test of a submarine cable. In a practical scenario, the submarine cable 306 to be tested is a long-distance submarine cable.

[0050] For example, a power supply 301 is connected to an excitation transformer 302, one end of which is connected to the input of a first shunt reactor assembly 303. The other end of the excitation transformer 302 is grounded. The output of the first shunt reactor assembly 303 is respectively connected to one end of a second shunt reactor assembly 304, one end of a voltage divider 305, and one end of a submarine cable under test 306. The other ends of the second shunt reactor assembly 304, the other ends of the voltage divider 305, and the other end of the submarine cable under test 306 are all grounded. Therefore, in the improved test circuit, the output of the excitation transformer is connected in series with m shunt reactors, and (nm) shunt reactors are connected in parallel with the submarine cable.

[0051] In this embodiment, by replacing the series reactor in the circuit with a parallel-parallel reactor, the current on the submarine cable 306 to be tested is shunted, thereby reducing the current passing through the power supply 301 and the capacity required to be provided by the power supply 301. This helps to meet the capacity requirement of the submarine cable 306 to be tested, thereby reducing the difficulty of implementing the submarine cable AC withstand voltage test.

[0052] In an exemplary embodiment, Figure 3 As shown, the reactors in the first shunt reactor combination 303 are the same as the reactors in the second shunt reactor combination 304 .

[0053] For example, since the reactors in the first parallel reactor combination 303 are the same as the reactors in the second parallel reactor combination 304, assuming that the inductance of a single reactor is L1, the rated current is I, and the cable capacitance is C1. Then, after (nm) reactors of the same specification are connected in parallel, the equivalent inductance is The rated current of the reactor is (nm)I; m reactors of the same specification are connected in parallel, which is equivalent to an inductance of The rated current of the reactor is mI. Since the DC resistance of the reactor is much smaller than the inductive reactance of the reactor, the effect of the DC resistance on the impedance of the test circuit can be ignored. Therefore, the impedance of m parallel reactors is: The impedance of the (nm) shunt reactor is: The capacitive reactance of submarine cable is: The impedance of the (nm) shunt reactors connected in parallel with the submarine cable is: Assume the total resistance of the test circuit is R Y , the total impedance of the test circuit is: When the circuit resonates: Can be obtained When the circuit resonates, ω=ω0, and Z m 、Z n-m 、Z c Substitute into the above formula So we can get the resonant frequency of the series-parallel resonant circuit as:

[0054] From this we can know that: Y0 =f X0 , that is, the improved hybrid resonant circuit has the same circuit characteristics as the series resonant circuit, that is, in the hybrid resonant circuit, the voltage across the reactor and the test piece is Q times the output voltage of the excitation transformer.

[0055] In this embodiment, by using the same inductor, the improved hybrid resonant circuit has the same characteristics as the traditional series resonant circuit, so that relevant technical personnel do not need to relearn completely new circuit principles and operating methods, and can quickly get started and skillfully use the improved circuit, which is conducive to accurately evaluating the performance and quality of submarine cables.

[0056] In an exemplary embodiment, Figure 4 As shown, the first parallel reactor combination 403 includes one reactor, and the second parallel reactor combination 404 includes at least two reactors.

[0057] like Figure 4 As shown, U is the output voltage of the excitation transformer, I T-min Refers to the output current of the excitation transformer, I Cis the submarine cable current, I1 refers to the current of the first reactor, I2 refers to the current of the second reactor, and I n Refers to the current of the nth reactor, I (3-(n-1)) It refers to the current of the 3rd to n-1th reactors, and also includes a voltage divider 405 and a voltmeter 407. It should be noted that, Figure 4 The voltage divider 405 and the voltmeter 407 are respectively Figure 3 The middle voltage divider 305 and the voltmeter 307 are the same and will not be described again here.

[0058] For example, in Figure 2 In the test circuit, when the loop resonates and boosts the voltage to the test voltage, let the test voltage be Uc. At this time, the test current is: I C =2πf X0 C1U C According to Kirchhoff's law, the output current of the excitation transformer is equal to the total current in the n parallel reactor circuits and equal to the cable test current, that is: I TX =I1+I2+…I n =I C The output power of the excitation transformer is: P X =UI TX =UI C =U2πf X0 C1U C .

[0059] exist Figure 3 In the test circuit, when the loop resonates and boosts the voltage to the test voltage, let the test voltage be Uc. At this time, the test current is: I C =2πf Y0 C1U C .

[0060] The output current I of the excitation transformer 302 TY Equal to the total current in the m shunt reactor circuits, that is:

[0061] At this time, the excitation transformer output power is: according to Figure 2 The output power formula of the excitation transformer in the test circuit can be obtained:

[0062] Therefore, compared with the series resonant circuit, in the parallel-parallel resonant circuit, the output power of the excitation transformer 302 depends on the number of series reactors with the excitation transformer. When m=1, as Figure 4 As shown, the output current and output power of the excitation transformer 402 are the smallest, which is 1 / n of that in the series resonant circuit, that is,

[0063] In summary, the optimized hybrid resonant circuit is as follows Figure 4 As shown, using this test method, the excitation transformer output power in the circuit is reduced to 1 / n of its original value (compared to a series resonant circuit). As the cable length increases, the capacity increases. Simply selecting an appropriate number of reactors of the same specification is sufficient to meet the test requirements, and the required capacity of power supply 401 remains 1 / n of the original value. Furthermore, since the low-voltage terminals of the n-1 shunt reactors are grounded, their operating current can also be monitored.

[0064] In this embodiment, by setting only one reactor in the first parallel reactor combination 403 and setting at least two reactors in the second parallel reactor combination 404, the submarine cable 406 (i.e. Figure 4 In the case of the capacity requirement of C1), the current value required to be provided by the power supply 401 is the smallest, and the energy consumption during the test is also reduced accordingly, which is conducive to meeting the requirements of energy saving and environmental protection.

[0065] In an exemplary embodiment, Figure 5 As shown, the system also includes: a first ammeter 508 and multiple second ammeters 509; one end of the first ammeter 508 is connected to the other end of the excitation transformer 502, one end of each second ammeter 509 is correspondingly connected to one end of an inductor in the second parallel reactor combination 504, and the other end of the first ammeter 508 and the other end of each second ammeter 509 are both grounded.

[0066] like Figure 5 As shown, U is the output voltage of the excitation transformer, I T-min Refers to the output current of the excitation transformer, I C is the submarine cable current, I1 refers to the current of the first reactor, I2 refers to the current of the second reactor, and I n Refers to the current of the nth reactor, I (3-(n-1)) Refers to the current of the 3rd to n-1th reactors, and also includes a power supply 501, a first parallel reactor combination 503, a second parallel reactor combination 504, a voltage divider 505, and a submarine cable to be tested 506 (i.e. Figure 5 C1 in), voltmeter 507. It should be noted that, Figure 5 The power supply 501, the first parallel reactor combination 503, the second parallel reactor combination 504, the voltage divider 505, the submarine cable to be tested 506, and the voltmeter 507 are respectively connected to Figure 4 The middle power source 401 , the first shunt reactor assembly 403 , the second shunt reactor assembly 404 , the voltage divider 405 , the submarine cable to be tested 406 , and the voltmeter 407 are the same and are not described in detail here.

[0067] The first ammeter 508 is an ammeter for monitoring the current passing through the first shunt reactor.

[0068] The second ammeter 509 is an ammeter for monitoring the current passing through the second shunt reactor.

[0069] It should be noted that the first ammeter 508 and the second ammeter 509 are both ammeters commonly used in the market for AC withstand voltage tests of submarine cables, such as clamp ammeters, electronic ammeters, and the like.

[0070] For example, one end of first ammeter 508 is connected to the other end of excitation transformer 502, one end of each second ammeter 509 is connected to one end of a reactor in second shunt reactor assembly 504, and the other end of first ammeter 508 and the other end of each second ammeter 509 are grounded. During the AC withstand voltage test of the submarine cable, first ammeter 508 measures the current passing through the first shunt reactor, and second ammeter 509 measures the current passing through the second shunt reactor.

[0071] In this embodiment, an ammeter is provided to monitor the current passing through the reactor in real time, so that abnormal current conditions can be discovered in a timely manner. For example, excessive current may indicate a short circuit or other fault, which is conducive to taking measures in advance to avoid accidents and thus ensure the safety of test personnel and equipment.

[0072] In an exemplary embodiment, Figure 3 As shown, the voltage divider 305 includes a plurality of capacitors connected in series.

[0073] Among them, the capacitor is a capacitor module commonly used in the market for AC withstand voltage testing of submarine cables.

[0074] Exemplarily, a plurality of capacitors connected in series are provided in the voltage divider 305 , the output ends of the first shunt reactor combination 303 are respectively connected to one end of the plurality of capacitors connected in series, and the other ends of the plurality of capacitors connected in series are grounded.

[0075] In this embodiment, by setting a capacitor, the reactive power in the circuit can be compensated and the power factor of the power supply 301 can be improved; moreover, together with components such as inductors, a series or parallel resonant circuit is formed to achieve high voltage and high current output at a specific frequency to meet the requirements of the withstand voltage test.

[0076] In an exemplary embodiment, Figure 3 As shown, the voltage divider 305 further includes a voltmeter 307; two ends of the voltmeter 307 are respectively connected to two ends of one capacitor among the multiple capacitors connected in series.

[0077] The voltmeter 307 is a voltmeter commonly used in the market for AC withstand voltage testing of submarine cables, such as a peak voltmeter.

[0078] For example, the two ends of the voltmeter 307 are respectively connected to the two ends of one capacitor among the plurality of capacitors connected in series. During the AC withstand voltage test of the submarine cable, the voltmeter 307 obtains the voltage value across the two ends of the capacitor.

[0079] In this embodiment, by providing a voltmeter 307 to monitor the voltage across the capacitor, the voltage applied to the submarine cable can be monitored, thereby avoiding irreversible damage to the submarine cable caused by excessive voltage, which is beneficial to ensuring the safety of the submarine cable.

[0080] In an exemplary embodiment, Figure 3 As shown, the excitation transformer 302 is a variable frequency excitation transformer.

[0081] Among them, the variable frequency excitation transformer is equipped with an iron core and a coil. The iron core is made of silicon steel sheets and the coil is wound with copper wire.

[0082] Exemplarily, the power supply 301 is connected to a variable frequency excitation transformer, one end of the variable frequency excitation transformer is connected to the input end of the first shunt reactor combination 303, and the other end of the variable frequency excitation transformer is grounded.

[0083] In this embodiment, a variable frequency excitation transformer is provided to provide the reactor with an input voltage that meets the test requirements.

[0084] In an exemplary embodiment, Figure 3 As shown, the power supply 301 is an AC power supply.

[0085] Illustratively, the AC power source is connected to the excitation transformer 302 .

[0086] In this embodiment, an AC power supply is provided so that the circuit can reach a resonant state by adjusting the power supply frequency.

[0087] In an exemplary embodiment, Figure 3 As shown, the inductance of the excitation transformer 302 is in the mH level, and the inductance of the reactors in the first shunt reactor combination 303 and the reactors in the second shunt reactor combination 304 are both in the H level.

[0088] For example, since the inductance of the excitation transformer high voltage winding is mH level, the inductance of the reactor is H level, the difference is 10 3 The above order of magnitude, so the influence of the excitation transformer high voltage winding inductance on the test circuit can be ignored. The voltage divider capacitance is pF level, the cable capacitance is μF level, the difference is 10 6 The above order of magnitude, therefore the effect of the voltage divider capacitance on the capacitive reactance of the test circuit can also be ignored.

[0089] In this embodiment, by setting different levels of inductance for the excitation transformer 302 and the shunt reactor combination, the theoretical analysis and calculation of the test loop are greatly simplified. There is no need to overly consider the complex factor of the excitation transformer high-voltage winding inductance, thereby focusing more on the influence of major components such as the reactor on the loop characteristics, which is conducive to improving calculation efficiency and accuracy.

[0090] In an exemplary embodiment, Figure 3 As shown, the test frequency of the system is 20Hz-300Hz.

[0091] For example, the submarine cable AC withstand voltage test system is used for AC withstand voltage test of long-distance high-voltage submarine cables. The implementation process is as follows:

[0092] (1) Calculate the capacity of the cable based on its parameters.

[0093] (2) According to the requirements of the regulations, the cable AC withstand voltage test frequency is 20Hz-300Hz. From the above analysis, it can be seen that the hybrid resonant circuit has: Because long-distance cables have large capacity, a larger C1 and a higher test frequency mean a smaller inductance L1 is required. However, the actual inductance L1 of the reactor is relatively large, making it more difficult to achieve the desired value with a higher test frequency. Therefore, in engineering implementation, a starting test frequency of 20Hz is used as a guideline for calculating the required equipment.

[0094] (3) Take the lowest test frequency at resonance as 20 Hz and calculate the maximum inductance required to meet the test requirements based on the cable capacity: That is, at least n reactors with an inductance of L1 are required.

[0095] (4) Take the lowest test frequency at resonance as 20Hz and calculate the test current of the cable: I C =2πf Y0 C1U C .

[0096] (5) According to the test current, the current of the series reactor with the excitation transformer is obtained:

[0097] (6) According to I TY The size of the reactor and the required maximum inductance are comprehensively considered to select the reactor with appropriate parameters and determine its number n to ensure that the inductance of the reactor can meet the requirements of the test frequency and the rated voltage is greater than I TY .

[0098] (7) After obtaining n, I can be calculated TY The specific size of is determined, and the excitation transformer 302 that satisfies the output current is selected based on the result.

[0099] (8) Assume that the excitation transformer 302 ratio is K, according to I TY The current at the input can be obtained as KI TY , select the appropriate power supply 301 according to the current at the input end of the excitation transformer, that is, the output current needs to be greater than KI TY Power supply 301.

[0100] (9) After selecting the equipment, Figure 4 The circuit is wired. According to the placement of the equipment, the low-voltage end of a reactor close to the excitation transformer is connected in series with the output end of the excitation transformer. The high-voltage end is then connected in parallel with the high-voltage end of other reactors and then connected to the test cable. The low-voltage end of other reactors is grounded and led to a suitable position through the grounding wire (keeping a sufficient safe distance from the reactor and convenient for test personnel to monitor) so that its current can be monitored during the test.

[0101] (10) Carry out AC withstand voltage test on the cable according to the requirements of the regulations: adjust the test frequency in the circuit to resonance, increase the voltage to the specified test voltage value, and continue for the specified time (usually 60 minutes). If there is no discharge breakdown or other phenomena during the continuous process, the test is passed.

[0102] (11) During the test, the current of the reactor, excitation transformer 302 and power supply 301 should be monitored. If any abnormality is found, the voltage should be reduced in time.

[0103] At the same time, this test method is a hybrid resonance test method based on the improvement of series resonance, which can obtain a high voltage with a quality factor Q times the output voltage of the excitation transformer at the high voltage end, and can meet the high voltage requirement of the AC withstand voltage test; this test method can greatly reduce the power supply capacity required by the conventional test method, reduce the capacity of the variable frequency power supply and the excitation transformer 302, and reduce the size of the required equipment; due to the improvement of the test wiring, this test method can monitor the working current of the reactor in real time. If there is an abnormality during the test, the test current will change, and the abnormality can be discovered in time by monitoring the working current of the reactor; this test method It can be applied to AC withstand voltage tests of long-distance high-voltage submarine cables of 500kV and below. Due to differences in cable voltage and length, the capacity of the tested cable will be different. It is only necessary to calculate and select the appropriate number of reactors that meet the test requirements based on the cable capacity (by increasing or decreasing the number of reactors of the same specification to meet the test frequency requirements). The reactor connected in series with the output end of the excitation transformer remains one, and the required power capacity remains unchanged. Compared with series resonance, all the low-voltage ends of the reactors are connected in parallel. In this test method, the low-voltage end of the reactor is grounded, and its working current can be monitored in real time. Abnormal conditions such as reactor failure can be discovered in time.

[0104] In this embodiment, since submarine cables of different types and specifications may have different responses to voltages of different frequencies, setting a wider frequency range can better adapt to the characteristics of various cables and ensure the effectiveness of the test.

[0105] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0106] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0107] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0108] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0109] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0110] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A submarine cable AC withstand voltage test system, characterized in that: The system comprises: a power supply, an excitation transformer, a first shunt reactor combination, a second shunt reactor combination and a voltage divider; The power supply is connected to the excitation transformer, one end of the excitation transformer is connected to the input end of the first shunt reactor assembly, and the other end of the excitation transformer is grounded; the output end of the first shunt reactor assembly is respectively connected to one end of the second shunt reactor assembly, one end of the voltage divider, and one end of the submarine cable to be tested; the other end of the second shunt reactor assembly, the other end of the voltage divider, and the other end of the submarine cable to be tested are all grounded.

2. The system according to claim 1, wherein: The reactor in the first shunt reactor combination is the same as the reactor in the second shunt reactor combination; The reactor includes an oil-immersed reactor.

3. The system according to claim 1, wherein: The first parallel reactor combination includes one reactor, and the second parallel reactor combination includes at least two reactors.

4. The system according to claim 3, characterized in that The system further includes: a first ammeter and a plurality of second ammeters; One end of the first ammeter is connected to the other end of the excitation transformer, one end of each second ammeter is correspondingly connected to one end of a reactor in the second shunt reactor combination, and the other end of the first ammeter and the other end of each second ammeter are both grounded.

5. The system according to claim 1, wherein: The voltage divider includes a plurality of capacitors connected in series.

6. The system according to claim 5, characterized in that The voltage divider also includes a voltmeter; Two ends of the voltmeter are respectively connected to two ends of one capacitor among the multiple capacitors connected in series.

7. The system according to claim 1, wherein: The excitation transformer is a variable frequency excitation transformer.

8. The system according to claim 1, wherein: The power supply is an AC power supply.

9. The system according to claim 1, wherein: The inductance of the excitation transformer is in the mH class, and the inductance of the reactors in the first shunt reactor combination and the reactors in the second shunt reactor combination are both in the H class.

10. The system according to any one of claims 1 to 9, characterized in that The test frequency of the system is 20 Hz-300 Hz.

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