10kV distribution cable oscillatory wave partial discharge detection method and system

Abstract

The embodiment of the invention provides a 10kV distribution cable oscillatory wave partial discharge detection method and system, and is applied to the technical field of cable detection. The method is applied to the detection system, a control instruction carrying a preset test voltage and a detection mode is obtained, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection; responding to the control instruction, determining a connection state of a high-voltage relay corresponding to the detection mode, and driving a three-phase partial discharge detection unit to generate detection data of the to-be-detected 10kV distribution cable based on a preset test voltage and the connection state of the high-voltage relay; the computer filters the detection data acquired by the sampling module to obtain partial discharge data and voltage signals; and determining a detection result based on the partial discharge data and the voltage signal. Detection modes can be independently selected according to test requirements, the composition structure of the detection system is adjusted based on the detection modes to achieve detection, the cable detection process is simplified, three phases of the cable can be detected at the same time, and the cable detection efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of cable detection, and in particular to a method and system for detecting oscillating wave partial discharge of a 10kV distribution cable. Background Art

[0002] 10kV distribution cables are widely used, and ensuring their stable operation is of great significance to urban and industrial distribution networks. Partial discharge detection technology is generally used to detect the insulation of 10kV distribution cables.

[0003] At present, the PD detection technology commonly used in on-site inspection of 10kV distribution cables is the oscillation wave detection technology, which can effectively detect and locate the PD defects in 10kV distribution cables.

[0004] According to the detection procedures, the oscillation wave detection requires separate detection of the three phases of the 10kV distribution cable. First detect one of the phases, and ground the conductors and shielding layers of the other two non-detection phases. After completing the detection of one of the phases, detect the next phase in the same way. During the phase change process, the grounding at the end of the cable also needs to be replaced. The whole process is time-consuming and labor-intensive, and the process is relatively cumbersome. If partial discharge detection of the three phases of the cable is carried out at the same time, the oscillation wave high-voltage output is directly connected to the three phases of the cable. The transmission process of the partial discharge signal in the parallel cable is very complicated, and it is difficult to locate defects. It can be seen that the methods used in the prior art for detecting 10kV distribution cables have the problem of low detection efficiency. Summary of the invention

[0005] In view of this, the present application provides a detection method and system for oscillating wave partial discharge of a 10kV distribution cable, which can simplify the detection process of the 10kV distribution cable, meet the requirements of simultaneously detecting three phases of the cable, and improve the detection efficiency of the 10kV distribution cable.

[0006] To solve the above problems, the technical solutions provided by this application are as follows:

[0007] In a first aspect, an embodiment of the present application provides a method for detecting oscillating wave partial discharge of a 10kV distribution cable. The detection method is applied to a detection system for oscillating wave partial discharge of a 10kV distribution cable. The detection system includes a DC high-voltage module, an adjustable charging resistance module, a high-voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module, and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested; the detection method includes:

[0008] Obtaining the control instruction generated by the computer, the control instruction carrying a preset test voltage and a detection mode of the 10 kV distribution cable to be tested determined according to the test requirements, the detection mode being any one of single-phase detection, two-phase detection and three-phase detection;

[0009] In response to the control instruction, the control module is driven to control the power amplifier circuit to generate a drive signal, wherein the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, instruct to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay;

[0010] Collecting the detection data through the sampling module;

[0011] The computer filters the detection data to obtain partial discharge data and voltage signals of the 10kV distribution cable to be tested; and determines the detection result of the 10kV distribution cable to be tested based on the partial discharge data and voltage signals.

[0012] Preferably, determining the detection result of the 10 kV distribution cable to be tested based on the partial discharge data and the voltage signal includes:

[0013] Constructing a partial discharge spectrum phase diagram based on the partial discharge data and the voltage signal;

[0014] The partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested.

[0015] Preferably, if the detection mode is single-phase detection, analyzing the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested includes:

[0016] If it is determined from the partial discharge spectrum phase diagram that a partial discharge pulse of a first amplitude exists in the first detection phase, then it is determined that partial discharge exists in the first detection phase.

[0017] Preferably, if the detection mode is two-phase detection, the analyzing the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested includes:

[0018] In the detection time period, obtaining a second amplitude corresponding to a partial discharge pulse existing in a second detection phase and a third amplitude corresponding to a partial discharge pulse existing in a third detection phase, and comparing the second amplitude with the third amplitude;

[0019] If the second amplitude is greater than the third amplitude, it is determined that partial discharge exists in the second detection phase and no partial discharge exists in the third detection phase;

[0020] If the third amplitudes are all greater than the second amplitudes, it is determined that partial discharge exists in the third detection phase and no partial discharge exists in the second detection phase;

[0021] If at the first preset moment the second amplitude is greater than the third amplitude, and at the second preset moment the third amplitude is greater than the second amplitude, it is determined that partial discharge exists in both the second detection phase and the third detection phase;

[0022] The first preset moment and the second preset moment are moments within the detection time period.

[0023] Preferably, if the detection mode is three-phase detection, the analyzing the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested includes:

[0024] In the detection time period, a fourth amplitude corresponding to the partial discharge pulse existing in the fourth detection phase, a fifth amplitude corresponding to the partial discharge pulse existing in the fifth detection phase, and a sixth amplitude corresponding to the partial discharge pulse existing in the sixth detection phase are obtained, and the fourth amplitude, the fifth amplitude, and the sixth amplitude are compared;

[0025] If the fourth amplitude is greater than both the fifth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fourth detection phase, and partial discharge does not exist in the fifth detection phase and the sixth detection phase;

[0026] If the fifth amplitude is greater than both the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fifth detection phase, and partial discharge does not exist in the fourth detection phase and the sixth detection phase;

[0027] If the sixth amplitude is greater than both the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the sixth detection phase, and partial discharge does not exist in the fourth detection phase and the fifth detection phase;

[0028] If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the fifth detection phase, and no partial discharge exists in the sixth detection phase;

[0029] If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the sixth detection phase, and no partial discharge exists in the fifth detection phase;

[0030] If at the third preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fifth detection phase and the sixth detection phase, and no partial discharge exists in the fourth detection phase;

[0031] If at the fifth preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, at the sixth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the seventh preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the fourth detection phase, the fifth detection phase, and the sixth detection phase;

[0032] Among them, the third preset time, the fourth preset time, the fifth preset time, the sixth preset time and the seventh preset time are times within the detection time period.

[0033] Preferably, the connection end between the detection phase and the three-phase partial discharge detection unit is the starting end; the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0034] Determine the pulse time difference of the same partial discharge pulse being detected according to the partial discharge pulse of the detection phase;

[0035] The distance between the partial discharge defect and the starting end is calculated based on the pulse time difference, the total length of the 10kV distribution cable to be tested, and the wave speed to obtain the defect location result of the 10kV distribution cable to be tested.

[0036] Preferably, filtering the detection data to obtain the partial discharge data and voltage signal of the 10 kV distribution cable to be tested includes:

[0037] Performing high-pass filtering on the detection data to obtain partial discharge data of the 10 kV distribution cable to be tested;

[0038] The detection data is low-pass filtered to obtain the voltage signal of the 10kV distribution cable to be tested.

[0039] Preferably, the detection method further comprises:

[0040] obtaining a first closing instruction generated by the computer;

[0041] In response to the first shutdown instruction, driving the control module to control the power amplifier circuit to generate a first shutdown signal, wherein the first shutdown signal is used to shut down the DC high voltage module;

[0042] If the preset test voltage is less than a preset multiple of the rated phase voltage of the 10kV distribution cable to be tested, and the voltage signal of the 10kV distribution cable to be tested decays to a first preset voltage value, or if the preset test voltage is greater than or equal to a preset multiple of the rated phase voltage of the 10kV distribution cable to be tested, and the voltage signal of the 10kV distribution cable to be tested decays to a second preset voltage value, then determine the moment when the voltage signal reaches a negative peak value, and obtain a second shutdown instruction generated by the computer;

[0043] In response to the second shutdown instruction, the control module is driven to control the power amplifier circuit to generate a second shutdown signal, wherein the second shutdown signal is used to shut down the high-voltage switch module and disconnect the high-voltage relay corresponding to the detection of the detection mode.

[0044] In a second aspect, an embodiment of the present application provides a detection system for oscillating wave partial discharge of a 10kV distribution cable, the detection system comprising a DC high voltage module, an adjustable charging resistance module, a high voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested;

[0045] The computer is connected to the control module and the sampling module respectively, and is used to generate a control instruction and send the control instruction to the control module; the control instruction carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection;

[0046] The control module is connected to the power amplifier circuit and is used to obtain and respond to the control instruction and control the power amplifier circuit to generate a driving signal;

[0047] The power amplifier circuit is respectively connected to the DC high-voltage module, the adjustable charging resistor module, the high-voltage switch module and the three-phase partial discharge detection unit, and is used to send the drive signal to the DC high-voltage module, the high-voltage switch module and the three-phase partial discharge detection unit, and the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, instruct to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate the detection data of the 10kV distribution cable to be tested;

[0048] The three-phase partial discharge detection unit is connected to the resonant inductor and the sampling module respectively, and is used to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay, and send the detection data to the sampling module;

[0049] The sampling module is used to collect the detection data and send the detection data to the computer;

[0050] The computer is further used for filtering the detection data to obtain partial discharge data and voltage signal of the 10kV distribution cable to be tested; and determining the detection result of the 10kV distribution cable to be tested based on the partial discharge data and voltage signal.

[0051] Preferably, the computer is used to determine the detection result of the 10kV distribution cable to be tested based on the partial discharge data and the voltage signal, including:

[0052] A partial discharge spectrum phase diagram is constructed based on the partial discharge data and the voltage signal; and the partial discharge spectrum phase diagram is analyzed according to a detection mode to obtain a detection result of the 10kV distribution cable to be tested.

[0053] Preferably, if the detection mode is single-phase detection, the computer is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0054] If it is determined from the partial discharge spectrum phase diagram that a partial discharge pulse of a first amplitude exists in the first detection phase, then it is determined that partial discharge exists in the first detection phase.

[0055] Preferably, if the detection mode is two-phase detection, the computer is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0056] In the detection time period, obtaining a second amplitude corresponding to a partial discharge pulse existing in a second detection phase and a third amplitude corresponding to a partial discharge pulse existing in a third detection phase, and comparing the second amplitude with the third amplitude;

[0057] If the second amplitude is greater than the third amplitude, it is determined that partial discharge exists in the second detection phase and no partial discharge exists in the third detection phase;

[0058] If the third amplitudes are all greater than the second amplitudes, it is determined that partial discharge exists in the third detection phase and no partial discharge exists in the second detection phase;

[0059] If at the first preset moment the second amplitude is greater than the third amplitude, and at the second preset moment the third amplitude is greater than the second amplitude, it is determined that partial discharge exists in both the second detection phase and the third detection phase;

[0060] The first preset moment and the second preset moment are moments within the detection time period.

[0061] Preferably, if the detection mode is three-phase detection, the computer is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0062] In the detection time period, a fourth amplitude corresponding to the partial discharge pulse existing in the fourth detection phase, a fifth amplitude corresponding to the partial discharge pulse existing in the fifth detection phase, and a sixth amplitude corresponding to the partial discharge pulse existing in the sixth detection phase are obtained, and the fourth amplitude, the fifth amplitude, and the sixth amplitude are compared;

[0063] If the fourth amplitude is greater than both the fifth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fourth detection phase, and partial discharge does not exist in the fifth detection phase and the sixth detection phase;

[0064] If the fifth amplitude is greater than both the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fifth detection phase, and partial discharge does not exist in the fourth detection phase and the sixth detection phase;

[0065] If the sixth amplitude is greater than both the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the sixth detection phase, and partial discharge does not exist in the fourth detection phase and the fifth detection phase;

[0066] If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the fifth detection phase, and no partial discharge exists in the sixth detection phase;

[0067] If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the sixth detection phase, and no partial discharge exists in the fifth detection phase;

[0068] If at the third preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fifth detection phase and the sixth detection phase, and no partial discharge exists in the fourth detection phase;

[0069] If at the fifth preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, at the sixth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the seventh preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the fourth detection phase, the fifth detection phase, and the sixth detection phase;

[0070] Among them, the third preset time, the fourth preset time, the fifth preset time, the sixth preset time and the seventh preset time are times within the detection time period.

[0071] Preferably, the connection end between the detection phase and the three-phase partial discharge detection unit is the starting end; the computer is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0072] The pulse time difference of the same partial discharge pulse being detected is determined according to the partial discharge pulse of the detection phase; the distance between the partial discharge defect and the starting end is calculated based on the pulse time difference, the total length of the 10kV distribution cable to be tested, and the wave speed, so as to obtain the defect location result of the 10kV distribution cable to be tested.

[0073] Preferably, the computer is used to filter the detection data to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested, including:

[0074] The detection data is subjected to high-pass filtering to obtain partial discharge data of the 10 kV distribution cable to be tested; and the detection data is subjected to low-pass filtering to obtain a voltage signal of the 10 kV distribution cable to be tested.

[0075] Preferably, the computer is further used to generate a first closing instruction, and send the first closing instruction to the control module;

[0076] The control module is further used to obtain and respond to the first shutdown instruction, control the power amplifier circuit to generate a first shutdown signal, and the first shutdown signal is used to shut down the DC high-voltage module;

[0077] The computer is further configured to determine the moment when the voltage signal reaches a negative peak value, and generate a second shutdown instruction, if the preset test voltage is less than a preset multiple of the rated phase voltage of the 10 kV distribution cable to be tested, and the voltage signal of the 10 kV distribution cable to be tested decays to a first preset voltage value, or if the preset test voltage is greater than or equal to a preset multiple of the rated phase voltage of the 10 kV distribution cable to be tested, and the voltage signal of the 10 kV distribution cable to be tested decays to a second preset voltage value;

[0078] The control module is also used to obtain and respond to the second shutdown instruction, control the power amplifier circuit to generate a second shutdown signal, and the second shutdown signal is used to turn off the high-voltage switch module and the high-voltage relay corresponding to the detection of the disconnection detection mode.

[0079] In a third aspect, the present application provides a 10kV distribution cable oscillating wave partial discharge detection device, the device comprising: a processor, a memory, and a system bus;

[0080] The processor and the memory are connected via the system bus;

[0081] The memory is used to store one or more programs, and the one or more programs include instructions. When the instructions are executed by the processor, the processor executes the method for detecting oscillatory wave partial discharge of 10kV distribution cables described in the first aspect.

[0082] In a fourth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions. When the instructions are executed on a device, the device executes the method for detecting oscillating wave partial discharge of a 10kV distribution cable as described in the first aspect.

[0083] It can be seen that this application has the following beneficial effects:

[0084] An embodiment of the present application provides a method for detecting oscillating wave partial discharge of a 10kV distribution cable. The method is applied to a detection system, which includes a DC high-voltage module, an adjustable charging resistance module, a high-voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested. First, a control instruction generated by a computer is obtained, and the control instruction carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection; secondly, the drive control module responds to the control instruction, controls the power amplifier circuit to generate a drive signal, and the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, indicate to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay; the detection data is collected by the sampling module, and finally the detection data is filtered by the computer to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested; the detection result of the 10kV distribution cable to be tested is determined based on the partial discharge data and the voltage signal. In this way, the detection mode can be selected independently according to the test requirements, and the component structure of the detection system can be mobilized based on the detection mode to achieve detection, which simplifies the detection process of 10kV distribution cables and can meet the needs of simultaneous detection of three phases of the cable, thereby improving the detection efficiency of 10kV distribution cables.

[0085] The embodiment of the present application also provides a system corresponding to the above method, which has the same beneficial effects as the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 A schematic diagram of the structure of a 10kV distribution cable oscillating wave partial discharge detection system provided in an embodiment of the present application;

[0087] Figure 2 A schematic diagram of the circuit structure of the adjustable charging resistor module 2 provided in an embodiment of the present application;

[0088] Figure 3 A schematic diagram of the circuit structure of a three-phase partial discharge detection unit 3 provided in an embodiment of the present application;

[0089] Figure 4 A schematic flow chart of a method for detecting oscillating wave partial discharge of a 10kV distribution cable provided in an embodiment of the present application;

[0090] Figure 5 A schematic diagram of a single-phase detection process of a 10kV distribution cable provided in an embodiment of the present application;

[0091] Figure 6 A schematic diagram of a two-phase detection process of a 10kV distribution cable provided in an embodiment of the present application;

[0092] Figure 7 A schematic diagram of a three-phase detection process of a 10kV distribution cable provided in an embodiment of the present application;

[0093] Figure 8 A schematic diagram of an oscillation wave in a cable charging process provided in an embodiment of the present application;

[0094] Fig. 9 A schematic diagram of the structure of a 10kV distribution cable oscillating wave partial discharge detection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0095] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0096] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "comprise", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the statement "comprising a ..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0097] At present, the insulation of 10kV distribution cables needs to be tested separately for three phases one by one by using oscillation waves. First, detect one of the phases, and ground the conductors and shielding layers of the other two non-detection phases. After completing the detection of one of the phases, detect the next phase in the same way. During the phase change process, the grounding at the end of the cable also needs to be replaced. The whole process is time-consuming and labor-intensive, and the process is relatively cumbersome. With the implementation of the quality and efficiency improvement of power grid companies, some researchers have proposed to carry out partial discharge detection of the three phases of the cable at the same time, and directly connect the oscillation wave high-voltage output directly to the three phases of the cable. However, the transmission process of the partial discharge signal in the parallel cable is very complicated, which causes great difficulties in defect location. It can be seen that the methods used in the existing technology for detecting 10kV distribution cables have the problems of cumbersome defect location and low detection efficiency.

[0098] The embodiment of the present application provides a detection method and system for oscillating wave partial discharge of a 10kV distribution cable. The detection method is applied to a detection system, which includes a DC high-voltage module, an adjustable charging resistance module, a high-voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module, and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested. First, a control instruction generated by a computer is obtained, and the control instruction carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection; secondly, the drive control module responds to the control instruction, controls the power amplifier circuit to generate a drive signal, and the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, indicate to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay; the detection data is collected by the sampling module, and finally the detection data is filtered by the computer to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested; the detection result of the 10kV distribution cable to be tested is determined based on the partial discharge data and the voltage signal. In this way, the detection mode can be selected independently according to the test requirements, and the component structure of the detection system can be mobilized based on the detection mode to achieve detection, which simplifies the detection process of 10kV distribution cables and can meet the needs of simultaneous detection of three phases of the cable, thereby improving the detection efficiency of 10kV distribution cables.

[0099] To facilitate understanding of the technical solution provided in the embodiment of the present application, a method and system for detecting oscillating wave partial discharge of a 10kV distribution cable provided in the embodiment of the present application are described below in conjunction with the accompanying drawings.

[0100] First, the detection system of oscillatory wave partial discharge of 10kV distribution cable is described.

[0101] See also Figure 1 , Figure 1 A schematic diagram of the structure of a 10kV distribution cable oscillating wave partial discharge detection system provided in an embodiment of the present application.

[0102] The detection system includes a DC high voltage module 1, an adjustable charging resistor module 2, a high voltage switch module S, a resonant inductor L, a three-phase partial discharge detection unit 3, a power amplifier circuit 4, a control module 5, a sampling module 6 and a computer 7. Among them, the power amplifier circuit 4 is connected to the DC high voltage module 1, the adjustable charging resistor module 2, the high voltage switch module S, the three-phase partial discharge detection unit 3 and the control module 5. The adjustable charging resistor module 2 is also connected to the DC high voltage module 1, the high voltage switch module S and the resonant inductor L. The resonant inductor L is also connected to the high voltage switch module S and the three-phase partial discharge detection unit 3. The sampling module 6 is connected to the three-phase partial discharge detection unit 3 and the computer 7. The control module 5 is also connected to the computer 7. The DC high voltage module 1, the high voltage switch module 5 and the three-phase partial discharge detection unit 3 are grounded respectively, and the DC high voltage module 1 is used to connect to an external 220V AC power, and the maximum DC high voltage generated is 30kV.

[0103] See also Figure 2 , Figure 2 A schematic diagram of the circuit structure of the adjustable charging resistor module 2 provided in the embodiment of the present application. The adjustable charging resistor module 2 is composed of high-voltage resistors R1-R4 and high-voltage relays J1-J3, R1=1MΩ, R2=R3=R4=4MΩ, and the control circuit of the high-voltage relays J1-J3 is connected to the control module 5, wherein the high-voltage relays J1-J3 can be high-voltage DC relays. In the process of charging the distribution cable, the adjustable charging resistor module 2 can gradually reduce the resistance of the charging resistor according to the charging voltage level, and dynamically adjust the resistance by controlling the opening and closing states of the high-voltage relays J1-J3, thereby reducing the charging time and improving the charging efficiency.

[0104] The high-voltage switch module 5 is composed of a plurality of bidirectional IGBT loops or a plurality of thyristors connected in series.

[0105] The resonant inductor L is composed of two high-voltage non-partial discharge hollow core inductors connected in series, one of which is connected in parallel with the high-voltage relay J7. The inductance value I of each inductor can be 0.5H, the DC resistance value RL of the inductor can be 12Ω, and the DC resistance value of the inductor is the resistance value of the device itself. The embodiment of the present application does not limit the inductance value of the inductor and the DC resistance value of the inductor, and the value of the relevant data of the electronic device can be determined according to the actual situation.

[0106] See also Figure 3 , Figure 3A schematic diagram of the circuit structure of the three-phase partial discharge detection unit 3 provided in the embodiment of the present application. The three-phase partial discharge detection unit 3 is composed of high-voltage relays J4-J6, blocking inductors LA, LB, LC and partial discharge detection impedances of each phase. The three-phase outputs of the three-phase partial discharge detection unit 3 are respectively connected to the A, B, and C three-phase core conductors of the 10kV distribution cable to be tested through high-voltage flexible cables. Other types of cables can also be used for connection, which is not limited in the embodiment of the present application. High-voltage flexible cables are generally used on site for easy connection.

[0107] The control circuit of the high-voltage relay J4-J6 is connected to the control module 5. The high-voltage relay J4-J6 can be a gas-insulated high-voltage relay with a peak operating voltage of 35kV, a continuous current sharing capability of 10A, and an operating time of 15ms.

[0108] Blocking inductors LA, LB, and LC are air-core non-partial discharge inductors with an inductance value of 1mH. Blocking inductors are used to block the high-frequency signals of partial discharge from phase to phase. The signals between phases will not be coupled, which is convenient for phase determination of partial discharge signals and improves the detection sensitivity of partial discharge detection impedance. Otherwise, the corresponding signals cannot be extracted for analysis.

[0109] The partial discharge detection impedance is composed of an RC type detection impedance, and its output is connected to the sampling module. By high-pass filtering the collected signal, partial discharge data can be obtained, and by low-pass filtering the collected signal, the voltage signal on the 10kV distribution cable to be tested can be obtained.

[0110] The control module 5 is used to receive instructions from the computer 7, such as control instructions, shutdown instructions, etc., and drive the power amplifier circuit 4 to generate corresponding drive signals to control the DC high-voltage module 1, the adjustable charging resistor module 2, the high-voltage switch module S and the three-phase partial discharge detection unit 3.

[0111] See also Figure 4 , Figure 4 A flow chart of a detection method for oscillating wave partial discharge of a 10kV distribution cable provided in an embodiment of the present application, the detection method is applied to the detection system for oscillating wave partial discharge of the aforementioned 10kV distribution cable, specifically including S401-S404. The 10kV distribution cable to be tested is stripped from the power grid after a power outage and discharged. The three-phase output of the three-phase partial discharge detection unit 3 is connected to the three-phase core conductor of the 10kV distribution cable to be tested through a high-voltage flexible cable. The terminal conductor of the 10kV distribution cable to be tested is suspended, and the shielding layer and armor layer of the three phases A, B, and C are grounded, and sufficient electrical distance is maintained between the three-phase core conductors.

[0112] Before starting the test, the control module 5 controls the high-voltage switch module S to be in the off state, and the high-voltage relays J1-J7 are in the off state. Set the test voltage Ut for this test, and select the detection mode of the 10kV distribution cable to be tested according to the test requirements. The detection mode is any one of single-phase detection, two-phase detection and three-phase detection. Among them, the test voltage Ut is specified by the standard, and the test voltage Ut is a multiple relationship with the rated phase voltage U0 of the 10kV distribution cable to be tested. For example, the commonly used 10kV distribution cable has a rated phase voltage U0 of 8.7kV. According to the test standard of the oscillation wave, the test voltage Ut is set to 0.5U0, 0.7U0, 0.9U0, 1U0 or 1.5U0, etc., which can be set according to actual needs.

[0113] S401: Acquire the control instruction generated by the computer, where the control instruction carries a preset test voltage and a detection mode of the 10 kV distribution cable to be tested determined according to test requirements.

[0114] The user can trigger the computer 7 to generate a control instruction, which carries the test voltage Ut and the detection mode. The detection mode is one of single-phase detection, two-phase detection or multi-phase detection selected by the user based on the test requirements, and the connection status of each device on the system is determined according to the detection mode so that the circuit connection of the measurement circuit meets the detection requirements of the detection mode.

[0115] It should be noted that the embodiments of the present application are applied to 10kV distribution cables and may also be applicable to other types of distribution cables. The 10kV distribution cable is only taken as an example and is not limited to this distribution cable.

[0116] For the specific implementation method of executing the detection operation corresponding to the detection mode, please refer to the description below.

[0117] S402: In response to the control instruction, the control module is driven to control the power amplifier circuit to generate a drive signal, wherein the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, instruct to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay.

[0118] The control instruction generated by the computer 7 is used to drive the control module 5 to control the power amplifier circuit 4 to generate a drive signal. The drive signal is used to implement the detection corresponding to the detection mode.

[0119] Specifically, the driving signal can be used to control the start-up of the DC high voltage module 1 to generate negative polarity DC high voltage. The DC high voltage module 1 is a relatively mature product, and only needs a given driving signal to generate DC high voltage. DC high voltage includes negative polarity DC high voltage and positive polarity DC high voltage. Negative polarity DC high voltage is generally used to detect distribution cables. Compared with positive polarity DC high voltage, negative polarity DC high voltage can better stimulate defects in distribution cables.

[0120] The drive signal can also be used to control the connection state of the high-voltage relays J1-J7 according to the detection mode and control the closing of the high-voltage switch module S. Before the detection starts, the high-voltage switch module S is controlled to close, and the opening and closing states of the high-voltage relays J1-J7 are controlled according to the detection mode.

[0121] Before the test is performed, the DC high-voltage module 1 is started to generate negative polarity DC high voltage; the three-phase partial discharge detection unit 3 detects the voltage signal of the 10kV distribution cable to be tested, and controls J1-J3 to close one by one according to the ratio of the test voltage preset by the voltage signal, so as to charge the 10kV distribution cable to be tested. After the charging is completed, the high-voltage switch module S is controlled to close, and the DC high-voltage module 1 is controlled to close. The 10kV distribution cable to be tested forms an LC damped oscillation circuit with the inductor to generate an oscillation wave, and the oscillation wave voltage and partial discharge signal are collected. The oscillation wave voltage signal is used to stimulate partial discharge at the insulation defect of the cable.

[0122] The voltage signal on the 10kV distribution cable to be tested will directly affect the amplitude and frequency of the oscillation wave signal.

[0123] When the voltage signal decays to a negative peak value, the high-voltage switch module is controlled to disconnect, and J1-J3 is disconnected.

[0124] If it is single-phase detection, the high-voltage relay J7 is controlled to be disconnected, and the opening and closing states of J4-J6 are controlled according to the detection phase.

[0125] If there are two detections, the control pressure relay J7 is closed, and the opening and closing states of J4-J6 are controlled according to the detection phase.

[0126] If it is three-phase detection, the control pressure relay J4-J7 is closed.

[0127] The driving signal can also be used to drive the three-phase partial discharge detection unit 3 to generate detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection status of the high-voltage relays J4-J7. After determining the detection mode and completing the connection of the corresponding high-voltage relay based on the detection mode, the detection of the 10kV distribution cable to be tested can be performed, and the detection data obtained by the detection can be analyzed to determine the partial discharge amount and defect location results.

[0128] S403: Collect the detection data through the sampling module.

[0129] The high voltage switch module S is closed to generate an oscillation wave, which is the detection data. The sampling module 6 collects the detection data from the three-phase partial discharge detection unit 3 and sends the detection data to the computer 7, which analyzes the detection data to obtain the detection result.

[0130] S404: The computer filters the detection data to obtain partial discharge data and voltage signals of the 10 kV distribution cable to be tested; and determines the detection result of the 10 kV distribution cable to be tested based on the partial discharge data and voltage signals.

[0131] The computer 7 filters the collected oscillation waves. In one possible implementation, the detection data is filtered to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested, including: high-pass filtering the detection data to obtain the partial discharge data of the 10kV distribution cable to be tested; low-pass filtering the detection data to obtain the voltage signal of the 10kV distribution cable to be tested.

[0132] By high-pass filtering the collected detection data, the partial discharge data of the 10kV distribution cable to be tested can be obtained; by low-pass filtering the collected detection data, the voltage signal of the 10kV distribution cable to be tested can be obtained.

[0133] In one possible implementation, determining the detection result of the 10kV distribution cable to be tested based on the partial discharge data and the voltage signal includes: constructing a partial discharge spectrum phase diagram based on the partial discharge data and the voltage signal; and analyzing the partial discharge spectrum phase diagram according to a detection mode to obtain the detection result of the 10kV distribution cable to be tested.

[0134] When the voltage reaches a certain level, defects in the cable insulation layer cannot withstand the applied electric field strength and cause partial discharge. The partial discharge data may include the discharge amplitude, phase, number, etc.

[0135] Under the same defect conditions, the higher the cable voltage, the greater the intensity (amplitude) of partial discharge. Higher voltage means greater electric field strength, and the increase in voltage signal will increase the possibility of partial discharge activity.

[0136] The horizontal axis of the phase resolved partial discharge (PRPD) spectrum is the phase angle, which represents different time points in an AC voltage cycle. These time points correspond to the voltage waveform of the voltage signal. The distribution of partial discharge activity at different phases of the voltage waveform can be observed through the PRPD spectrum.

[0137] By analyzing the partial discharge spectrum phase diagram, the detection results can be obtained. The detection results include partial discharge amount and positioning results, which can determine whether partial discharge exists, how much partial discharge is, and the location of the discharge, thereby completing the detection of 10kV distribution cables.

[0138] Based on the contents of the above steps S401-S404, it can be known that the detection system includes a DC high-voltage module, an adjustable charging resistance module, a high-voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested. First, a control instruction generated by a computer is obtained, which carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection; secondly, the drive control module responds to the control instruction, controls the power amplifier circuit to generate a drive signal, and the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, indicate to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay; the detection data is collected by the sampling module, and finally the computer filters the detection data to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested; the detection result of the 10kV distribution cable to be tested is determined based on the partial discharge data and the voltage signal. In this way, the detection mode can be selected independently according to the test requirements, saving detection time. The detection is realized by adjusting the component structure of the detection system based on the detection mode, which simplifies the detection process of 10kV distribution cables, meets the needs of simultaneous detection of three phases of the cable, and improves the detection efficiency of 10kV distribution cables.

[0139] In another embodiment of the present application, the processes of single-phase detection, two-phase detection and three-phase detection are described respectively.

[0140] See also Figure 5 , Figure 5 A schematic diagram of a single-phase detection process of a 10kV distribution cable provided in an embodiment of the present application. The detection mode is single-phase detection. In a possible implementation, the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including: determining from the partial discharge spectrum phase diagram that there is a partial discharge pulse of a first amplitude in the first detection phase, then determining that there is partial discharge in the first detection phase.

[0141] Initialize the circuit system, control the DC high voltage module 1 to start, and generate negative polarity DC high voltage. The three-phase partial discharge detection unit 3 detects that the voltage signal of the 10kV distribution cable to be tested reaches 0.3Ut, then the control module 5 controls J1 to close; the voltage signal of the 10kV distribution cable to be tested reaches 0.5Ut, then the control module 5 controls J2 to close; the voltage signal of the 10kV distribution cable to be tested reaches 0.8Ut, then the control module 5 controls J3 to close; the voltage signal of the 10kV distribution cable to be tested reaches Ut, then the control module 5 controls the high-voltage switch module S to close and the DC high voltage module 1 to close, generating an oscillation wave, and the acquisition module 6 acquires the oscillation wave voltage and partial discharge signal.

[0142] By determining that the attenuation of the voltage signal reaches the preset threshold, it is possible to determine the moment when the voltage signal of the 10kV distribution cable to be tested reaches the negative peak value. Specifically, if Ut<1.3U0, when the voltage signal decays to 0.1Ut, the voltage signal is detected to reach the negative peak moment, and the control module 5 controls the high-voltage switch module S to disconnect, and controls the high-voltage relay corresponding to the test to disconnect. If Ut≥1.3U0, when the voltage signal decays to 0.05Ut, the voltage signal is detected to reach the negative peak moment, and the control module 5 controls the high-voltage switch module S to disconnect, and controls the high-voltage relay corresponding to the test to disconnect.

[0143] If the test phase is phase A, J4 is controlled to be disconnected; if the test phase is phase B, J5 is controlled to be disconnected; if the test phase is phase C, J6 is controlled to be disconnected.

[0144] When conducting the oscillation wave test, disconnect J1-J3. Close the high-voltage relay corresponding to the test and perform the test. If the detection mode is single-phase detection, the control module 5 controls the high-voltage relay J7 to be disconnected through the power amplifier circuit 4. If the test is performed on phase A, the high-voltage relay J4 is controlled to be closed, and the high-voltage relays J5 and J6 are disconnected. If the test is performed on phase B, the high-voltage relay J5 is controlled to be closed, and the high-voltage relays J4 and J6 are disconnected. If the test is performed on phase C, the high-voltage relay J6 is controlled to be closed, and the high-voltage relays J4 and J5 are disconnected.

[0145] The connection end between the detection phase and the three-phase partial discharge detection unit is the starting end (i.e., the test end). In a possible implementation method, the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including: determining the pulse time difference of the same partial discharge pulse detected according to the partial discharge pulse of the detection phase; calculating the distance between the partial discharge defect and the starting end based on the pulse time difference, the total length of the 10kV distribution cable to be tested, and the wave speed to obtain the defect location result of the 10kV distribution cable to be tested.

[0146] The test results include defect location results, which are analyzed and located according to the partial discharge signal of the test phase. The distance between the partial discharge defect position and the test end is l PD The calculation of is shown in the following formula (1):

[0147] l PD =l-Δt·v / 2 (1)

[0148] Wherein, l is the total length of the cable, △t is the pulse time difference of the same partial discharge signal being detected, and v is the wave velocity. The partial discharge pulses of the first amplitude V1 are repeatedly detected, and the pulse time difference △t is calculated from the adjacent partial discharge pulses of the first amplitude V1.

[0149] Through the above-mentioned single-phase detection, there is no need to switch the detection phases one by one, and there is no need to replace the end grounding of the 10kV distribution cable to be tested during the phase change process. By switching the high-voltage relay, each phase can be detected one by one. The process is simple, less time-consuming, and improves the detection efficiency.

[0150] See also Figure 6 , Figure 6 A schematic diagram of a two-phase detection process of a 10kV distribution cable provided in an embodiment of the present application. The detection mode is two-phase detection, and the detection phases include a second detection phase and a third detection phase; in a possible implementation method, the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including: within the detection time period, obtaining a second amplitude corresponding to a partial discharge pulse existing in the second detection phase and a third amplitude corresponding to a partial discharge pulse existing in the third detection phase, and comparing the second amplitude with the third amplitude.

[0151] If the second amplitudes are all greater than the third amplitudes, it is determined that partial discharge exists in the second detection phase and no partial discharge exists in the third detection phase; if the third amplitudes are all greater than the second amplitudes, it is determined that partial discharge exists in the third detection phase and no partial discharge exists in the second detection phase.

[0152] If the second amplitude is greater than the third amplitude at the first preset moment, and the third amplitude is greater than the second amplitude at the second preset moment, it is determined that partial discharge exists in both the second detection phase and the third detection phase; wherein the first preset moment and the second preset moment are moments within the detection time period.

[0153] The specific steps of initializing the circuit system and the specific steps of voltage signal attenuation can refer to the content described in single-phase detection. When the voltage signal of the 10kV distribution cable to be tested reaches the negative peak moment, the control module 5 controls the high-voltage switch module S to disconnect and controls the high-voltage relay corresponding to the test to disconnect.

[0154] If the test phases are phase A and phase B, J4 and J5 are controlled to be disconnected; if the test phases are phase A and phase C, J4 and J6 are controlled to be disconnected; if the test phases are phase B and phase C, J5 and J6 are controlled to be disconnected.

[0155] When conducting the oscillation wave test, disconnect J1-J3. Close the high-voltage relay corresponding to the test and perform the test. If the detection mode is two-phase detection, the control module 5 controls the high-voltage relay J7 to be closed through the power amplifier circuit 4. If the test is performed on phases A and B, the high-voltage relays J4 and J5 are controlled to be closed, and the high-voltage relay J6 is disconnected. If the test is performed on phases A and C, the high-voltage relays J4 and J6 are controlled to be closed, and the high-voltage relay J5 is disconnected. If the test is performed on phases B and C, the high-voltage relays J5 and J6 are controlled to be closed, and the high-voltage relay J4 is disconnected.

[0156] In the detection time period, a second amplitude V2 corresponding to the partial discharge pulse existing in the second detection phase and a third amplitude V3 corresponding to the partial discharge pulse existing in the third detection phase are obtained from the partial discharge spectrum phase diagram, and the second amplitude V2 and the third amplitude V3 are compared. The second detection phase and the third detection phase can be any combination of phase A and phase B, phase A and phase C, and phase B and phase C.

[0157] If there is a partial discharge pulse in the second detection phase at the first preset time t1, and the corresponding pulse is the second amplitude V2, and there is no pulse exceeding the noise background in the third detection phase at time t1, or there is a pulse with the third amplitude V3, and the second amplitude V2 is greater than the third amplitude V3, then it is considered that there is a partial discharge in the detection phase of the second amplitude V2 pulse. The first preset time t1 is any time within the detection time period.

[0158] During the entire detection period, the second amplitude V2 is greater than the third amplitude V3, that is, there is partial discharge in the second detection phase, but there is no partial discharge in the third detection phase.

[0159] The partial discharge defect position in the second detection phase is located according to the above formula (1).

[0160] Correspondingly, if there is a local discharge pulse in the third detection phase at time t1, and the pulse has a third amplitude V3; there is no pulse exceeding the noise background in the second detection phase at time t1, or there is a pulse with a third amplitude V2, and the third amplitude V3 is greater than the second amplitude V2, then it is considered that there is local discharge in the third detection phase.

[0161] During the entire detection time period, the third amplitude V3 is greater than the second amplitude V2, and it is determined that partial discharge exists in the third detection phase, and no partial discharge exists in the second detection phase.

[0162] The partial discharge defect position in the third detection phase is located according to the above formula (1).

[0163] In the scenario where both detected phases have partial discharge defects, the partial discharge pulses of different phases are generally generated at different times. It is only necessary to determine which phase has a larger discharge pulse amplitude at a certain moment.

[0164] If at the first preset time t1, there is a pulse signal with a second amplitude V2 in the second detection phase, and there is no pulse signal in the third detection phase or the pulse signal is the third amplitude V3, and the second amplitude V2 is greater than the third amplitude V3; at the second preset time t2, there is a pulse signal with a third amplitude V3 in the third detection phase, and there is no pulse signal in the second detection phase or the pulse signal is the second amplitude V2, and the third amplitude V3 is greater than the second amplitude V2, it can be determined that partial discharge exists in both the second detection phase and the third detection phase, and the pulse signal corresponding to the detection is generated by the partial discharge defect phase in the detection phase, and the partial discharge defect position of each phase is calculated based on formula (1).

[0165] The first preset time t1 and the second preset time t2 are times within the detection time period.

[0166] See also Figure 7 , Figure 7 A schematic diagram of a three-phase detection process of a 10kV distribution cable provided in an embodiment of the present application. The detection mode is three-phase detection, and the detection phases include a fourth detection phase, a fifth detection phase, and a sixth detection phase.

[0167] In one possible implementation, a partial discharge spectrum phase diagram is analyzed according to a detection mode to obtain a detection result of the 10 kV distribution cable to be tested, including: within a detection time period, obtaining a fourth amplitude corresponding to a partial discharge pulse existing in a fourth detection phase, a fifth amplitude corresponding to a partial discharge pulse existing in a fifth detection phase, and a sixth amplitude corresponding to a partial discharge pulse existing in a sixth detection phase, and comparing the fourth amplitude, the fifth amplitude, and the sixth amplitude.

[0168] If the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, it is determined that local discharge exists in the fourth detection phase, and no local discharge exists in the fifth detection phase and the sixth detection phase; if the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, it is determined that local discharge exists in the fifth detection phase, and no local discharge exists in the fourth detection phase and the sixth detection phase; if the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that local discharge exists in the sixth detection phase, and no local discharge exists in the fourth detection phase and the fifth detection phase.

[0169] If at the third preset moment the fourth amplitude is greater than the fifth and sixth amplitudes, and at the fourth preset moment the fifth amplitude is greater than the fourth and sixth amplitudes, it is determined that partial discharge exists in both the fourth and fifth detection phases, but no partial discharge exists in the sixth detection phase.

[0170] If at the third preset moment the fourth amplitude is greater than the fifth and sixth amplitudes, and at the fourth preset moment the sixth amplitude is greater than the fourth and fifth amplitudes, it is determined that partial discharge exists in both the fourth and sixth detection phases, but no partial discharge exists in the fifth detection phase.

[0171] If at the third preset moment the fifth amplitude is greater than the fourth and sixth amplitudes, and at the fourth preset moment the sixth amplitude is greater than the fourth and fifth amplitudes, it is determined that partial discharge exists in both the fifth and sixth detection phases, but no partial discharge exists in the fourth detection phase.

[0172] If at the fifth preset moment the fourth amplitude is greater than the fifth and sixth amplitudes, at the sixth preset moment the fifth amplitude is greater than the fourth and sixth amplitudes, and at the seventh preset moment the sixth amplitude is greater than the fourth and fifth amplitudes, then it is determined that partial discharge exists in the fourth detection phase, the fifth detection phase, and the sixth detection phase.

[0173] The specific steps for initializing the circuit system and the specific steps for voltage signal attenuation can refer to the content described in single-phase detection. When the voltage signal of the 10kV distribution cable to be tested reaches the negative peak moment, the control module 5 controls the high-voltage switch module S to disconnect and controls the high-voltage relay corresponding to the test to disconnect. The test phases are A phase, B phase and C phase, and J4-J6 are controlled to disconnect.

[0174] When conducting the oscillation wave test, J1-J3 are disconnected. The corresponding high-voltage relay is closed for testing. If the detection mode is three-phase detection, the control module 5 controls the high-voltage relay J7 to be closed through the power amplifier circuit 4; and controls the high-voltage relays J4-J6 to be closed.

[0175] During the detection time period, a fourth amplitude V4 corresponding to the local discharge pulse in the fourth detection phase, a fifth amplitude V5 corresponding to the local discharge pulse in the fifth detection phase, and a sixth amplitude V6 corresponding to the local discharge pulse in the sixth detection phase are obtained from the local discharge spectrum phase diagram, and the fourth amplitude V4, the fifth amplitude V5 and the sixth amplitude V6 are compared.

[0176] If any one of the fourth amplitude V4, the fifth amplitude V5 and the sixth amplitude V6 is greater than the other two amplitudes within the detection time period, local discharge exists in the detection phase corresponding to the any one amplitude, and no local discharge exists in the detection phases corresponding to the other two amplitudes.

[0177] If at the third preset time t3, there is a pulse signal with a fourth amplitude V4 in the fourth detection phase, there is no pulse signal in the fifth detection phase or the pulse signal is the fifth amplitude V5, there is no pulse signal in the sixth detection phase or the pulse signal is the sixth amplitude V6, the fourth amplitude V4 is greater than the fifth amplitude V5, and the fourth amplitude V4 is greater than the sixth amplitude V6; at the fourth preset time t4, there is a pulse signal with a fifth amplitude V5 in the fifth detection phase, there is no pulse signal in the fourth detection phase or the pulse signal is the fourth amplitude V4, there is no pulse signal in the sixth detection phase or the pulse signal is the sixth amplitude V6, the fifth amplitude V5 is greater than the fourth amplitude V4, and the fifth amplitude V5 is greater than the sixth amplitude V6; then it is determined that partial discharge exists in the fourth test phase and the fifth test phase, and no partial discharge exists in the sixth test phase.

[0178] Similarly, it can be known that there is a possibility that partial discharge exists in the fourth test phase and the sixth test phase, but not in the fifth test phase; there is a possibility that partial discharge exists in the fifth test phase and the sixth test phase, but not in the fourth test phase.

[0179] If at the fifth preset time t5, there is a pulse signal with a fourth amplitude V4 in the fourth detection phase, there is no pulse signal in the fifth detection phase or the pulse signal is the fifth amplitude V5, there is no pulse signal in the sixth detection phase or the pulse signal is the sixth amplitude V6, the fourth amplitude V4 is greater than the fifth amplitude V5, and the fourth amplitude V4 is greater than the sixth amplitude V6; at the sixth preset time t6, there is a pulse signal with a fifth amplitude V5 in the fifth detection phase, there is no pulse signal in the fourth detection phase or the pulse signal is the fourth amplitude V4, there is no pulse signal in the sixth detection phase or the pulse signal is the sixth amplitude V6 The pulse signal is the sixth amplitude V6, the fifth amplitude V5 is greater than the fourth amplitude V4, and the fifth amplitude V5 is greater than the sixth amplitude V6; at the seventh preset time t7, there is a pulse signal with the sixth amplitude V6 in the sixth detection phase, there is no pulse signal in the fourth detection phase or the pulse signal is the fourth amplitude V4, there is no pulse signal in the fifth detection phase or the pulse signal is the fifth amplitude V5, the sixth amplitude V6 is greater than the fourth amplitude V4, and the sixth amplitude V6 is greater than the fifth amplitude V5; it is determined that partial discharge exists in the fourth test phase, the fifth test phase and the sixth detection phase.

[0180] Among them, the third preset time t3, the fourth preset time t4, the fifth preset time t5, the sixth preset time t6 and the seventh preset time t7 are times within the detection time period.

[0181] The partial discharge defect position of the detection phase where partial discharge exists is located according to the above formula (1).

[0182] In this way, the phase-changing operation can be avoided through the adjustable high-voltage relay, saving the time and labor cost of phase-changing; the detection system supports simultaneous detection of two phases or simultaneous detection of three phases, saving measurement time, overcoming the problem that the existing technology cannot locate defects in three phases at the same time, and improving detection efficiency.

[0183] In another embodiment of the present application, the specific steps of attenuating the aforementioned voltage signal are described.

[0184] When the voltage signal of the 10kV distribution cable to be tested reaches Ut, the first shutdown instruction generated by the computer 7 is obtained. In response to the first shutdown instruction, the drive control module 5 controls the power amplifier circuit 4 to generate a first shutdown signal, which is used to shut down the DC high-voltage module 1.

[0185] If the preset test voltage Ut is less than the preset multiple of the rated phase voltage U0 of the 10kV distribution cable to be tested, and the voltage signal of the 10kV distribution cable to be tested decays to the first preset voltage value, or the preset test voltage Ut is greater than or equal to the preset multiple of the rated phase voltage U0 of the 10kV distribution cable to be tested, and the voltage signal of the 10kV distribution cable to be tested decays to the second preset voltage value, then it is determined that the voltage signal reaches the negative peak moment. After the voltage signal reaches the negative peak moment, the second shutdown instruction generated by the computer 7 is obtained; in response to the second shutdown instruction, the drive control module 5 controls the power amplifier circuit 4 to generate a second shutdown signal, which is used to turn off the high-voltage switch module S and the high-voltage relay corresponding to the detection of the disconnection detection mode.

[0186] Among them, the preset multiple of the rated phase voltage U0 of the 10kV distribution cable to be tested can be 1.3 times, that is, the size relationship between Ut and 1.3U0 is determined; the first preset voltage value can be 0.1Ut, and the second preset voltage value can be 0.05Ut. The embodiment of the present application is not limited to this and can be selected according to actual needs.

[0187] See also Figure 8 , Figure 8 A schematic diagram of an oscillation wave in a cable charging process provided in an embodiment of the present application.

[0188] In the above three different detection modes, after reaching the negative peak value, the high-voltage switch module S is disconnected and the corresponding high-voltage relay is detected.

[0189] At the negative peak of the voltage, the current is 0, so the high-voltage switch module S can be disconnected.

[0190] The embodiment of the present application charges the 10kV distribution cable to be tested with a negative polarity DC voltage, and turns off the high-voltage switch module S at the negative polarity peak value, so that the electric energy stored in the cable has no release path, and the cable can maintain the negative polarity voltage. Moreover, the voltage level has been determined (less than 0.1Ut or 0.05Ut), and the voltage value is low and will not affect the switch.

[0191] When the voltage is boosted next time (for example, 0.5U0 needs to be tested once, then 0.7U0 needs to be tested three times, then 1U0 needs to be tested three times, and so on), the cable can be charged through the negative polarity DC high-voltage module 1 based on the existing voltage of the cable itself. The cable itself also has a voltage with the same polarity, so there is no need to start charging from 0, which can improve charging efficiency and save energy.

[0192] The above-mentioned embodiment of the present application provides a detection method for 10kV distribution cable oscillating wave partial discharge based on the above-mentioned. Next, a detection system for 10kV distribution cable oscillating wave partial discharge also provided in the embodiment of the present application is described, which is used to perform the above-mentioned Figure 4 Next, the function of the detection system for 10kV distribution cable oscillation wave partial discharge is described. The structural schematic diagram of the detection system for 10kV distribution cable oscillation wave partial discharge is shown in FIG. Figure 1 As shown, it includes a DC high-voltage module 1, an adjustable charging resistance module 2, a high-voltage switch module S, a resonant inductor L, a three-phase partial discharge detection unit 3, a power amplifier circuit 4, a control module 5, a sampling module 6 and a computer 7.

[0193] in,

[0194] The three-phase partial discharge detection unit 3 is connected to the three-phase core conductor of the 10kV distribution cable to be tested;

[0195] The computer 7 is connected to the control module 5 and the sampling module 6 respectively, and is used to generate a control instruction and send the control instruction to the control module 5; the control instruction carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection;

[0196] The control module 5 is connected to the power amplifier circuit 4, and is used to obtain and respond to the control instruction, and control the power amplifier circuit 4 to generate a driving signal;

[0197] The power amplifier circuit 4 is respectively connected to the DC high voltage module 1, the adjustable charging resistor module 2, the high voltage switch module S and the three-phase partial discharge detection unit 3, and is used to send the drive signal to the DC high voltage module 1, the high voltage switch module S and the three-phase partial discharge detection unit 3, and the drive signal is used to control the DC high voltage module 1 to start generating negative polarity DC high voltage, instruct to control the connection state of the high voltage relay according to the detection mode, control the closing of the high voltage switch module S, and drive the three-phase partial discharge detection unit 3 to generate the detection data of the 10kV distribution cable to be tested;

[0198] The three-phase partial discharge detection unit 3 is connected to the resonant inductor L and the sampling module 6 respectively, and is used to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay, and send the detection data to the sampling module 6;

[0199] The sampling module 6 is used to collect the detection data and send the detection data to the computer 7;

[0200] The computer 7 is further used for filtering the detection data to obtain partial discharge data and voltage signal of the 10kV distribution cable to be tested; and determining the detection result of the 10kV distribution cable to be tested based on the partial discharge data and voltage signal.

[0201] Preferably, the computer 7 is used to determine the detection result of the 10kV distribution cable to be tested based on the partial discharge data and the voltage signal, including:

[0202] A partial discharge spectrum phase diagram is constructed based on the partial discharge data and the voltage signal; and the partial discharge spectrum phase diagram is analyzed according to a detection mode to obtain a detection result of the 10kV distribution cable to be tested.

[0203] Preferably, if the detection mode is single-phase detection, the computer 7 is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0204] If it is determined from the partial discharge spectrum phase diagram that a partial discharge pulse of a first amplitude exists in the first detection phase, then it is determined that partial discharge exists in the first detection phase.

[0205] Preferably, if the detection mode is two-phase detection, the computer 7 is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0206] In the detection time period, obtaining a second amplitude corresponding to a partial discharge pulse existing in a second detection phase and a third amplitude corresponding to a partial discharge pulse existing in a third detection phase, and comparing the second amplitude with the third amplitude;

[0207] If the second amplitude is greater than the third amplitude, it is determined that partial discharge exists in the second detection phase and no partial discharge exists in the third detection phase;

[0208] If the third amplitudes are all greater than the second amplitudes, it is determined that partial discharge exists in the third detection phase and no partial discharge exists in the second detection phase;

[0209] If at the first preset moment the second amplitude is greater than the third amplitude, and at the second preset moment the third amplitude is greater than the second amplitude, it is determined that partial discharge exists in both the second detection phase and the third detection phase;

[0210] The first preset moment and the second preset moment are moments within the detection time period.

[0211] Preferably, if the detection mode is three-phase detection, the computer 7 is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0212] In the detection time period, a fourth amplitude corresponding to the partial discharge pulse existing in the fourth detection phase, a fifth amplitude corresponding to the partial discharge pulse existing in the fifth detection phase, and a sixth amplitude corresponding to the partial discharge pulse existing in the sixth detection phase are obtained, and the fourth amplitude, the fifth amplitude, and the sixth amplitude are compared;

[0213] If the fourth amplitude is greater than both the fifth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fourth detection phase, and partial discharge does not exist in the fifth detection phase and the sixth detection phase;

[0214] If the fifth amplitude is greater than both the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fifth detection phase, and partial discharge does not exist in the fourth detection phase and the sixth detection phase;

[0215] If the sixth amplitude is greater than both the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the sixth detection phase, and partial discharge does not exist in the fourth detection phase and the fifth detection phase;

[0216] If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the fifth detection phase, and no partial discharge exists in the sixth detection phase;

[0217] If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the sixth detection phase, and no partial discharge exists in the fifth detection phase;

[0218] If at the third preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fifth detection phase and the sixth detection phase, and no partial discharge exists in the fourth detection phase;

[0219] If at the fifth preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, at the sixth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the seventh preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the fourth detection phase, the fifth detection phase, and the sixth detection phase;

[0220] Among them, the third preset time, the fourth preset time, the fifth preset time, the sixth preset time and the seventh preset time are times within the detection time period.

[0221] Preferably, the connection end between the detection phase and the three-phase partial discharge detection unit 3 is the starting end; the computer 7 is used to analyze the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including:

[0222] The pulse time difference of the same partial discharge pulse being detected is determined according to the partial discharge pulse of the detection phase; the distance between the partial discharge defect and the starting end is calculated based on the pulse time difference, the total length of the 10kV distribution cable to be tested, and the wave speed, so as to obtain the defect location result of the 10kV distribution cable to be tested.

[0223] Preferably, the computer 7 is used to filter the detection data to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested, including:

[0224] The detection data is subjected to high-pass filtering to obtain partial discharge data of the 10 kV distribution cable to be tested; and the detection data is subjected to low-pass filtering to obtain a voltage signal of the 10 kV distribution cable to be tested.

[0225] Preferably, the computer 7 is further used to generate a first closing instruction, and send the first closing instruction to the control module 5;

[0226] The control module 5 is further used to obtain and respond to the first shutdown instruction, and control the power amplifier circuit 4 to generate a first shutdown signal, wherein the first shutdown signal is used to shut down the DC high voltage module 1;

[0227] The computer 7 is further configured to determine the moment when the voltage signal reaches a negative peak value, and generate a second closing instruction, if the preset test voltage is less than a preset multiple of the rated phase voltage of the 10 kV distribution cable to be tested, and the voltage signal of the 10 kV distribution cable to be tested decays to a first preset voltage value; or, if the preset test voltage is greater than or equal to a preset multiple of the rated phase voltage of the 10 kV distribution cable to be tested, and the voltage signal of the 10 kV distribution cable to be tested decays to a second preset voltage value;

[0228] The control module 5 is further used to obtain and respond to the second shutdown instruction, control the power amplifier circuit 4 to generate a second shutdown signal, and the second shutdown signal is used to turn off the high-voltage switch module S and the high-voltage relay corresponding to the detection of the disconnection detection mode.

[0229] An embodiment of the present application provides a detection system for oscillating wave partial discharge of a 10kV distribution cable, the detection system comprising a DC high-voltage module, an adjustable charging resistance module, a high-voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested.

[0230] The computer is connected to the control module and the sampling module respectively, and is used to generate a control instruction, and sends the control instruction to the control module; the control instruction carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection. The control module is connected to the power amplifier circuit, and is used to obtain and respond to the control instruction, and control the power amplifier circuit to generate a drive signal. The power amplifier circuit is connected to the DC high-voltage module, the adjustable charging resistance module, the high-voltage switch module and the three-phase partial discharge detection unit respectively, and is used to send a drive signal to the DC high-voltage module, the high-voltage switch module and the three-phase partial discharge detection unit, and the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, indicate to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate the detection data of the 10kV distribution cable to be tested. The three-phase partial discharge detection unit is connected to the resonant inductor and the sampling module respectively, and is used to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay, and send the detection data to the sampling module. The sampling module is used to collect the detection data and send the detection data to the computer; the computer is also used to filter the detection data to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested; the detection result of the 10kV distribution cable to be tested is determined based on the partial discharge data and voltage signal. In this way, the detection mode can be selected independently according to the test requirements, and the composition structure of the detection system can be mobilized based on the detection mode to achieve detection, which simplifies the detection process of the 10kV distribution cable, and can meet the needs of simultaneous detection of the three phases of the cable, thereby improving the detection efficiency of the 10kV distribution cable.

[0231] Based on the above method embodiment, a detection method for 10kV distribution cable oscillating wave partial discharge is provided. The present application embodiment provides a detection device for 10kV distribution cable oscillating wave partial discharge. Fig. 9 , the device includes: a processor, a memory, and a system bus;

[0232] The processor and the memory are connected via the system bus;

[0233] The memory is used to store one or more programs, and the one or more programs include instructions. When the instructions are executed by the processor, the processor executes the method for detecting oscillatory wave partial discharge of 10kV distribution cables described in any one of the above embodiments.

[0234] Based on a method for detecting oscillating wave partial discharge of a 10kV distribution cable provided in the above method embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores instructions. When the instructions are executed on a device, the device executes the method for detecting oscillating wave partial discharge of a 10kV distribution cable described in any of the above embodiments.

[0235] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0236] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0237] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting oscillating wave partial discharge of a 10kV distribution cable, characterized in that: The detection method is applied to a detection system for oscillating wave partial discharge of a 10kV distribution cable, the detection system comprising a DC high voltage module, an adjustable charging resistance module, a high voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested; the detection method comprises: Obtaining the control instruction generated by the computer, the control instruction carrying a preset test voltage and a detection mode of the 10 kV distribution cable to be tested determined according to the test requirements, the detection mode being any one of single-phase detection, two-phase detection and three-phase detection; In response to the control instruction, the control module is driven to control the power amplifier circuit to generate a drive signal, wherein the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, instruct to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay; Collecting the detection data through the sampling module; The computer filters the detection data to obtain partial discharge data and voltage signals of the 10kV distribution cable to be tested; and determines the detection result of the 10kV distribution cable to be tested based on the partial discharge data and voltage signals.

2. The detection method according to claim 1, characterized in that: Determining the detection result of the 10kV distribution cable to be tested based on the partial discharge data and the voltage signal, comprising: Constructing a partial discharge spectrum phase diagram based on the partial discharge data and the voltage signal; The partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested.

3. The detection method according to claim 2, characterized in that: If the detection mode is single-phase detection, analyzing the partial discharge spectrum phase diagram according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested includes: If it is determined from the partial discharge spectrum phase diagram that a partial discharge pulse of a first amplitude exists in the first detection phase, then it is determined that partial discharge exists in the first detection phase.

4. The detection method according to claim 2, characterized in that: If the detection mode is two-phase detection, the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including: In the detection time period, obtaining a second amplitude corresponding to a partial discharge pulse existing in a second detection phase and a third amplitude corresponding to a partial discharge pulse existing in a third detection phase, and comparing the second amplitude with the third amplitude; If the second amplitude is greater than the third amplitude, it is determined that partial discharge exists in the second detection phase and no partial discharge exists in the third detection phase; If the third amplitudes are all greater than the second amplitudes, it is determined that partial discharge exists in the third detection phase and no partial discharge exists in the second detection phase; If at the first preset moment the second amplitude is greater than the third amplitude, and at the second preset moment the third amplitude is greater than the second amplitude, it is determined that partial discharge exists in both the second detection phase and the third detection phase; The first preset moment and the second preset moment are moments within the detection time period.

5. The detection method according to claim 2, characterized in that: If the detection mode is three-phase detection, the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including: In the detection time period, a fourth amplitude corresponding to the partial discharge pulse existing in the fourth detection phase, a fifth amplitude corresponding to the partial discharge pulse existing in the fifth detection phase, and a sixth amplitude corresponding to the partial discharge pulse existing in the sixth detection phase are obtained, and the fourth amplitude, the fifth amplitude, and the sixth amplitude are compared; If the fourth amplitude is greater than both the fifth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fourth detection phase, and partial discharge does not exist in the fifth detection phase and the sixth detection phase; If the fifth amplitude is greater than both the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in the fifth detection phase, and partial discharge does not exist in the fourth detection phase and the sixth detection phase; If the sixth amplitude is greater than both the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the sixth detection phase, and partial discharge does not exist in the fourth detection phase and the fifth detection phase; If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the fifth detection phase, and no partial discharge exists in the sixth detection phase; If at the third preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fourth detection phase and the sixth detection phase, and no partial discharge exists in the fifth detection phase; If at the third preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the fourth preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in both the fifth detection phase and the sixth detection phase, and no partial discharge exists in the fourth detection phase; If at the fifth preset moment the fourth amplitude is greater than the fifth amplitude and the sixth amplitude, at the sixth preset moment the fifth amplitude is greater than the fourth amplitude and the sixth amplitude, and at the seventh preset moment the sixth amplitude is greater than the fourth amplitude and the fifth amplitude, it is determined that partial discharge exists in the fourth detection phase, the fifth detection phase, and the sixth detection phase; Among them, the third preset time, the fourth preset time, the fifth preset time, the sixth preset time and the seventh preset time are times within the detection time period.

6. The detection method according to any one of claims 3 to 5, characterized in that: The connection end between the detection phase and the three-phase partial discharge detection unit is the starting end; the partial discharge spectrum phase diagram is analyzed according to the detection mode to obtain the detection result of the 10kV distribution cable to be tested, including: Determine the pulse time difference of the same partial discharge pulse being detected according to the partial discharge pulse of the detection phase; The distance between the partial discharge defect and the starting end is calculated based on the pulse time difference, the total length of the 10kV distribution cable to be tested, and the wave speed to obtain the defect location result of the 10kV distribution cable to be tested.

7. The detection method according to claim 1, characterized in that: The filtering of the detection data to obtain the partial discharge data and voltage signal of the 10kV distribution cable to be tested includes: Performing high-pass filtering on the detection data to obtain partial discharge data of the 10 kV distribution cable to be tested; The detection data is low-pass filtered to obtain the voltage signal of the 10kV distribution cable to be tested.

8. The detection method according to claim 1, characterized in that: The detection method further comprises: obtaining a first closing instruction generated by the computer; In response to the first shutdown instruction, driving the control module to control the power amplifier circuit to generate a first shutdown signal, wherein the first shutdown signal is used to shut down the DC high voltage module; If the preset test voltage is less than a preset multiple of the rated phase voltage of the 10kV distribution cable to be tested, and the voltage signal of the 10kV distribution cable to be tested decays to a first preset voltage value, or if the preset test voltage is greater than or equal to a preset multiple of the rated phase voltage of the 10kV distribution cable to be tested, and the voltage signal of the 10kV distribution cable to be tested decays to a second preset voltage value, then determine the moment when the voltage signal reaches a negative peak value, and obtain a second shutdown instruction generated by the computer; In response to the second shutdown instruction, the control module is driven to control the power amplifier circuit to generate a second shutdown signal, wherein the second shutdown signal is used to shut down the high-voltage switch module and disconnect the high-voltage relay corresponding to the detection of the detection mode.

9. A 10kV distribution cable oscillating wave partial discharge detection system, characterized in that: The detection system includes a DC high-voltage module, an adjustable charging resistance module, a high-voltage switch module, a resonant inductor, a three-phase partial discharge detection unit, a power amplifier circuit, a control module, a sampling module and a computer; the three-phase partial discharge detection unit is connected to the three-phase core conductor of the 10kV distribution cable to be tested; The computer is connected to the control module and the sampling module respectively, and is used to generate a control instruction and send the control instruction to the control module; the control instruction carries a preset test voltage and a detection mode of the 10kV distribution cable to be tested determined according to the test requirements, and the detection mode is any one of single-phase detection, two-phase detection and three-phase detection; The control module is connected to the power amplifier circuit and is used to obtain and respond to the control instruction and control the power amplifier circuit to generate a driving signal; The power amplifier circuit is respectively connected to the DC high-voltage module, the adjustable charging resistor module, the high-voltage switch module and the three-phase partial discharge detection unit, and is used to send the drive signal to the DC high-voltage module, the high-voltage switch module and the three-phase partial discharge detection unit, and the drive signal is used to control the DC high-voltage module to start generating negative polarity DC high voltage, instruct to control the connection state of the high-voltage relay according to the detection mode, control the closing of the high-voltage switch module, and drive the three-phase partial discharge detection unit to generate the detection data of the 10kV distribution cable to be tested; The three-phase partial discharge detection unit is connected to the resonant inductor and the sampling module respectively, and is used to generate the detection data of the 10kV distribution cable to be tested based on the preset test voltage and the connection state of the high-voltage relay, and send the detection data to the sampling module; The sampling module is used to collect the detection data and send the detection data to the computer; The computer is further used for filtering the detection data to obtain partial discharge data and voltage signal of the 10kV distribution cable to be tested; and determining the detection result of the 10kV distribution cable to be tested based on the partial discharge data and voltage signal.

10. The detection system according to claim 9, characterized in that: The computer is used to determine the detection result of the 10kV distribution cable to be tested based on the partial discharge data and the voltage signal, comprising: A partial discharge spectrum phase diagram is constructed based on the partial discharge data and the voltage signal; and the partial discharge spectrum phase diagram is analyzed according to a detection mode to obtain a detection result of the 10kV distribution cable to be tested.

Images