Method, system, equipment and medium for detecting residual current of low-voltage AC cable for station use

Abstract

The present invention relates to a method, system, device and medium for detecting residual current of a low-voltage AC cable for a station. The method comprises: arranging a topological structure including a host and a plurality of slaves in a low-voltage AC power supply system; the host is used to collect electrical parameter information of the low-voltage AC cable, and the slave is used to collect residual current measurement values ​​of each circuit in the system; the host and the slave perform data synchronous acquisition through a working mode of switching between asynchronous and synchronous modes; and based on the synchronous data sets collected by the host and the slave, perform residual current vector synthesis calculation based on a phase angle reference system of two sections of low-voltage AC cables. Compared with the traditional method, the present invention does not increase other external hardware costs, has no auxiliary components and cables, reuses existing communication lines, and realizes high-precision synchronous acquisition through asynchronous and synchronous mode switching. The present invention adopts a residual current vector synthesis calculation method based on a phase angle reference system of two sections of low-voltage AC cables, which can avoid calculation errors between different coordinate systems.

Description

Technical Field

[0001] The present invention relates to the field of low-voltage alternating current power supply for stations in the electric power industry, and in particular to a method, system, equipment and medium for detecting residual current of a low-voltage alternating current cable for stations. Background Art

[0002] In recent years, station-use low-voltage AC power supply systems have been widely used in the power industry. However, the frequent accidents caused by low-voltage AC cable insulation failures have had a significant impact on power safety and caused huge economic losses. From the perspective of the causes of electrical fire accidents, according to the different properties of the short-circuit contact points, they can be divided into metallic short circuits and ground fault short circuits. Metallic short circuits refer to short circuits between live conductors, which are mainly caused by mechanical damage or overload of the cable. Ground fault short circuits refer to short circuits between live conductors and the earth, including non-metallic pipes and components connected to the outer casing and the ground, which will cause arc short circuits. The factors that cause fault short circuits are mainly mechanical damage to the cable under the friction of the pipe or the electrical line due to overheating, water immersion, mildew, etc., which reduces the insulation level of the cable. Under the action of external factors, the insulation is broken down and short-circuited.

[0003] Among accidents caused by low-voltage AC cable insulation failure, ground fault short circuit is particularly hidden and has a high probability of occurrence, which is mainly caused by cable insulation damage. In order to meet this challenge, the power industry specification recommends the use of residual current monitoring devices for electrical fire protection. In particular, in the scenario of residual current detection of low-voltage AC cables in stations, such as dual power supply lines such as DC power supply systems and communication power supply systems in substations, residual current detection is particularly important.

[0004] In the scenario of residual current detection of low-voltage AC cables in stations, such as Figure 1 As shown, the residual current is the current whose vector sum of the current of each phase line and the neutral line is not zero. The dual-power common neutral line circuit is a power supply circuit in which the neutral line is connected in parallel on the load side because a three-pole circuit breaker or a three-pole switching device is used in the circuit. For example, it is a dual-power supply line such as the DC power supply system and the communication power supply system in the substation. The detection of the residual current in the common neutral line circuit is relatively complicated. The detection of the residual current becomes complicated because the neutral lines of the two sections of the circuit are connected in parallel. When any section of the cable generates a neutral line current, it may be diverted from the neutral line of the other section of the power system, resulting in a deviation between the monitored residual current value and the actual value. Therefore, how to accurately detect the residual current and perform vector synthesis according to the corresponding reference system has become an urgent problem to be solved.

[0005] To solve the problem of residual current vector synthesis, the existing technology mainly adopts the following three methods:

[0006] The first is to directly connect the output terminals of the transformer (residual current or three-phase current + N-line current) in parallel, first synthesize the current signal through hardware, and then collect it through direct hardware methods such as electric energy metering IC. This method is simple to implement and common, but it has more wiring, poor adaptability to working conditions, and relies on external phase angle reference. It is mainly suitable for application scenarios with low accuracy requirements or simple working conditions. Although this method is simple to implement, it has complex wiring, poor adaptability to working conditions, is easy to introduce interference signals, and also relies on external phase angle reference.

[0007] The second method is to measure the near-end and far-end phase currents and calculate the residual current using the differential current method. Since the currents at both ends need to be measured, twice the number of transformers is required. The entire acquisition process is sensitive to the time deviation caused by synchronization. This method has relatively simple and clear wiring, but it is only applicable to single-section feeder loops, not to common neutral feeder loops. The differential current method requires more transformers and has high requirements for synchronization accuracy. It is often necessary to use auxiliary methods to achieve synchronization of the acquisition and measurement devices, which adds additional circuits and costs. If there is a deviation in synchronization, it is easy to have a significant impact on the results.

[0008] The third method is to continuously collect and synthesize the residual current. This method continuously collects the residual current signal at multiple points, synthesizes the waveform first, and then calculates the amplitude and phase. This method can reduce the error in the synthesis calculation process of the common neutral feeder. However, it also has high requirements for synchronization accuracy, and auxiliary methods are needed to synchronize the acquisition and measurement devices. This not only adds additional circuits and costs, but may also have a significant impact on the results due to synchronization deviations.

[0009] It can be seen that although the prior art provides a variety of residual current detection methods, the following major defects still exist: 1. Limited synchronization accuracy: The prior art mostly uses external hard signal sources other than residual current acquisition for synchronization, such as phase voltage, phase current, zero crossing, external hardware pulses, etc. The synchronization accuracy of these methods is limited and it is difficult to meet the needs of high-precision detection. 2. Increased cost and construction difficulty: In order to achieve synchronization, additional hardware circuits and corresponding cables need to be added. This not only increases the difficulty of construction, but also increases the cost of the system. 3. Reduced system reliability: Additional hardware circuits and cables increase the complexity of the system, thereby reducing the reliability of the system. Summary of the invention

[0010] In view of this, it is necessary to provide a station-use low-voltage AC cable residual current detection method, system, device and medium to solve the above-mentioned defects of the prior art.

[0011] In order to solve the above problems, in a first aspect, an embodiment of the present invention provides a method for detecting residual current of a low-voltage AC cable for a station, comprising:

[0012] S1, arranging a topological structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine a phase reference basis of the low-voltage AC cables; the slaves are used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system;

[0013] S2, the master and slave collect data by switching between asynchronous and synchronous modes to obtain a synchronized data set;

[0014] S3, according to the synchronous data sets collected by the master and slaves, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, the residual current measurement values ​​collected by the slaves are translated and vector synthesized to obtain the residual current vector value of each loop.

[0015] Preferably, in step S2, the host and the slave perform data synchronous acquisition by switching between asynchronous and synchronous modes, including:

[0016] S21, the system uses asynchronous mode to collect data during normal operation, and the host and the slave interact with each other in an asynchronous master-slave query mode;

[0017] S22, when the preset conditions are met, the system enters the synchronization mode, which includes the timing synchronization mode and the burst synchronization mode; in the synchronization mode, high-precision time synchronization between the host and the slave is achieved by sending a specific mode switching command and an IO hard pulse sequence.

[0018] Preferably, in step S22, the workflow of the timing synchronization mode includes:

[0019] When the periodic synchronization mode reaches its ΔT, the system automatically enters the timing synchronization mode:

[0020] The host issues a mode switching command to notify all slaves to switch modes;

[0021] The master and slave then enter a silent state in order to receive and process the synchronization signal;

[0022] The host sends an IO hard pulse sequence to each slave, and the corresponding port of the slave is in interrupt mode to ensure that the time of the host and all channel slaves is in high-precision synchronization;

[0023] Both the host and the slave use high-speed equal-interval continuous acquisition mode for data acquisition.

[0024] Preferably, in step S22, the workflow of the burst synchronization mode includes:

[0025] In asynchronous mode, when the data collected by the slave exceeds the set threshold, the system enters burst synchronization mode;

[0026] In burst synchronization mode, after timing synchronization, a token batch data transmission method based on time division multiple access is adopted to allocate a time window for the slaves of each channel. Each slave uses its own slave address as a token to upload the data collected in this synchronization in turn.

[0027] Preferably, the method of performing translation and vector synthesis calculation on the residual current measurement value collected by the slave based on the cable segment to which the loop belongs and the corresponding phase reference basis includes:

[0028] Obtain data collected synchronously by the host and slave, and calculate the phase angle of the data in the same reference system;

[0029] According to the section I / section II property setting of the corresponding circuit in the host, the translation and calculation of the phase angle coordinate system of the corresponding circuit are adjusted; wherein section I refers to section I low-voltage AC cable, section II refers to section II low-voltage AC cable, and the low-voltage AC power supply system includes section I low-voltage AC cable and section II low-voltage AC cable;

[0030] For the circuit of section I, the phase A voltage of section I is used as the zero vector reference basis; for the circuit of section II, the phase A voltage of section II is used as the zero vector reference basis; for the common neutral line circuit, the phase A voltage of section I or section II is used as the zero vector reference basis depending on the operation status of section I / section II of its switching device.

[0031] Preferably, in step S3, the method for calculating the residual current vector value of each loop includes:

[0032] For different types of loops, different vector synthesis calculation methods are used to calculate the residual current vector value of the corresponding loop; wherein the types of the loops include single-section feeder loops, single-section long feeder loops and common neutral line loops;

[0033] For the residual current vector value of the single-section feeder loop of section I and the single-section long feeder loop of section I, the phase A voltage of section I is used as the zero vector reference basis for translation calculation;

[0034] For the residual current vector value of the single-section feeder loop of section II and the single-section long feeder loop of section II, the phase A voltage of section II is used as the zero vector reference basis for translation calculation;

[0035] For the residual current vector value of the common neutral line loop, determine whether the loop belongs to section I or section II according to the commissioning status of the switching device. For the two residual current measurement values ​​in the common neutral line loop, and , respectively, taking the phase A voltage of the corresponding segment as the 0 vector reference basis for translation calculation, and calculating the translated and The vector synthesis value is used as the residual current vector value of the common neutral line loop.

[0036] Preferably, in step S3, the residual current vector synthesis calculation formula based on the phase angle reference system of the two sections of low-voltage AC cables includes:

[0037] The calculation formula for the residual current vector synthesis of the reference system of section I is:

[0038]

[0039] In the formula, represents the residual current vector after synthesis in the reference frame of section I, It represents the residual current vector of the feeder loop of section I in the reference system of section I, It represents the residual current vector of the feeder loop of section II in the reference frame of section I, It represents the phase angle of the feeder loop of section I in the reference system of section I, It represents the phase angle of the feeder loop of section II in the reference system of section I;

[0040] The calculation formula for the residual current vector synthesis of the reference system of section II is:

[0041]

[0042] In the formula, represents the residual current vector after synthesis in the reference frame of section II, It represents the phase angle of the feeder loop of section I in the reference system of section II, It represents the residual current vector of the feeder loop of section II in the reference system of section II, It represents the phase angle of the feeder loop of section I in the reference system of section II, It represents the phase angle of the section II feeder loop in the section II reference system.

[0043] In a second aspect, an embodiment of the present invention provides a station-used low-voltage AC cable residual current detection system, comprising:

[0044] A detection system building module is used to arrange a topology structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, and the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine a phase reference basis of the low-voltage AC cable; and the slave is used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system;

[0045] The data synchronization acquisition module is used for the host and the slave to acquire data by switching between asynchronous and synchronous modes to obtain a synchronous data set;

[0046] The calculation module is used to translate and vector synthesize the residual current measurement values ​​collected by the slave according to the synchronous data sets collected by the host and the slave, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, to obtain the residual current vector value of each loop.

[0047] In a third aspect, the present invention further provides an electronic device, including a memory and a processor, wherein:

[0048] The memory is used to store programs;

[0049] The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the station low-voltage AC cable residual current detection method as described in the embodiment of the first aspect of the present invention.

[0050] In a fourth aspect, the present invention further provides a computer-readable storage medium for storing computer-readable programs or instructions, which, when executed by a processor, can implement the steps of the station low-voltage AC cable residual current detection method as described in the embodiment of the first aspect of the present invention.

[0051] Compared with the prior art, the station-use low-voltage AC cable residual current detection method, system, device and medium provided by the present invention have at least the following beneficial effects:

[0052] 1) The system topology is simple, does not increase other external hardware costs, has no auxiliary components and cables, reuses existing communication lines, and achieves high-precision synchronous operation and token-based high-speed batch data transmission through asynchronous and synchronous mode switching.

[0053] 2) Based on high-precision synchronous acquisition of multiple channels and multiple detection units, the detection capacity and scale are improved, and the residual current calculation error caused by the synchronization time difference and the error caused by the different phases of the two segments are reduced.

[0054] 3) The present invention adopts a residual current vector synthesis calculation method based on the phase angle reference system of two low-voltage AC cables, which can accurately obtain the residual current of various types of loops. This method not only improves the accuracy of detection, but also has scalability, and can realize advanced analysis of the time section data of all parameters of the low-voltage AC power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A schematic diagram of a scenario of residual current detection of a low-voltage AC cable for a station in the prior art;

[0056] Figure 2 A flow chart of a method for detecting residual current of a low-voltage AC cable for a station provided by the present invention;

[0057] Figure 3 A system schematic diagram of residual current detection of low-voltage AC cables for stations provided by the present invention;

[0058] Figure 4 A schematic diagram of the operating status of the host and slave provided by the present invention;

[0059] Figure 5 A schematic diagram of the working process of the host and slave provided by the present invention;

[0060] Figure 6 A schematic diagram of the synchronization process of the host and the slave provided by the present invention;

[0061] Figure 7 A schematic diagram of the token batch transmission process provided by the present invention;

[0062] Figure 8 A schematic diagram of high-precision synchronization and batch data transmission of multiple channels and multiple units provided by the present invention;

[0063] Fig. 9 A schematic diagram of residual current measurement of each loop of two low-voltage AC cables provided by the present invention;

[0064] Fig.10 The principle diagram of the translation and calculation of the phase angle reference system based on two sections of low-voltage AC cables provided by the present invention;

[0065] Fig.11 The principle diagram of residual current vector synthesis based on the phase angle reference system of two sections of low-voltage AC cables provided by the present invention;

[0066] Fig.12 A structural block diagram of a station-use low-voltage AC cable residual current detection system provided by the present invention;

[0067] Fig.13 This is a structural block diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0068] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0069] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0070] In the scenario of residual current detection of low-voltage AC cables in stations, such as Figure 1 As shown, the residual current is the current whose vector sum of the current of each phase line and the neutral line is not zero. The dual-power common neutral line circuit is a power supply circuit in which the neutral line is connected in parallel on the load side because a three-pole circuit breaker or a three-pole switching device is used in the circuit. For example, it is a dual-power supply line such as the DC power supply system and the communication power supply system in the substation. The detection of the residual current in the common neutral line circuit is relatively complicated. The detection of the residual current becomes complicated because the neutral lines of the two sections of the circuit are connected in parallel. When any section of the cable generates a neutral line current, it may be diverted from the neutral line of the other section of the power system, resulting in a deviation between the monitored residual current value and the actual value. Therefore, how to accurately detect the residual current and perform vector synthesis according to the corresponding reference system has become an urgent problem to be solved.

[0071] Although the prior art provides a variety of residual current detection methods, the following major defects still exist: 1. Limited synchronization accuracy: The prior art mostly uses external hard signal sources other than residual current acquisition for synchronization, such as phase voltage, phase current, zero crossing, external hardware pulses, etc. The synchronization accuracy of these methods is limited and it is difficult to meet the needs of high-precision detection. 2. Increased cost and construction difficulty: In order to achieve synchronization, additional hardware circuits and corresponding cables need to be added. This not only increases the difficulty of construction, but also increases the cost of the system. 3. Reduced system reliability: Additional hardware circuits and cables increase the complexity of the system, thereby reducing the reliability of the system.

[0072] In view of this, the present invention provides a method and system for detecting residual current of a station low-voltage AC cable. Compared with the traditional method, the present invention does not increase other external hardware costs, has no auxiliary components and cables, reuses existing communication lines, and realizes high-precision synchronous operation and token-based high-speed batch data transmission through asynchronous and synchronous mode switching. The present invention adopts a residual current vector synthesis calculation method based on a two-stage low-voltage AC cable phase angle reference system, which can avoid calculation errors between different coordinate systems and improve the accuracy and reliability of residual current detection. The following will be explained and introduced through multiple embodiments.

[0073] Figure 2 The flow chart of the residual current detection method for low-voltage AC cable for station provided by the present invention is as follows: Figure 2 As shown, the residual current detection method of the low-voltage AC cable for a station includes at least steps S1 to S3, wherein:

[0074] Step S1, arranging a topological structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, and the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine the phase reference basis of the low-voltage AC cable; and the slave is used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system.

[0075] Figure 3 The system principle diagram of the residual current detection of low-voltage AC cable for station provided by the present invention, the present invention specifically relates to the field of low-voltage AC power supply for station using TN-S grounding method in the power industry (substation, converter station, switch station and series compensation station, etc.), the technical solution of the present invention is applicable to single cable, long cable and common neutral cable, wherein the common neutral cable has two busbars. Figure 3 In the system topology, the host is used to collect electrical parameter information of section I low-voltage AC cable and section II low-voltage AC cable. The two sections of low-voltage AC cable serve as independent power supply circuits respectively. The two sections of the circuits are connected in parallel on the load side through a neutral line to form a common neutral line circuit; the host is connected to each slave through multiple channels. Each slave is assigned to a different channel, and the slave is used to collect the residual current measurement value of each circuit in the system. In the embodiment of the present invention, section I low-voltage AC cable is also referred to as "section I", and section II low-voltage AC cable is also referred to as "section II". Section I low-voltage AC cable and section II low-voltage AC cable are collectively referred to as "two sections of AC".

[0076] In this embodiment, a multi-channel networking method is adopted to solve the problems of a large number of slaves, limited communication port driving capability, and wiring difficulties.

[0077] The host collects the electrical parameters of Section I / Section II and the operation status of Section I / Section II of each switching device to determine the residual current of each circuit based on the two-section AC phase reference. The host exchanges data and controls the process with all slaves through each channel, and completes the vector synthesis of the residual current based on the two-section AC phase reference according to the Section I / Section II properties of each circuit.

[0078] The slave collects the residual current of various types of loops, including single-section feeder loops ( Figure 3 CT3, CT4), single-section long feeder loop ( Figure 3 Between CT3 & CT5, between CT4 & CT6) and common neutral line circuit ( Figure 3 As a preferred implementation, the slave can also synchronously collect electrical parameter information such as voltage and current of the corresponding circuit to carry out data analysis based on time sections.

[0079] Step S2, the host and the slave collect data by switching between asynchronous and synchronous modes to obtain a synchronous data set;

[0080] In a preferred embodiment of the present invention, step S2 may specifically include the following steps S21-S22:

[0081] S21, the system uses asynchronous mode to collect data during normal operation, and the host and the slave interact with each other in an asynchronous master-slave query mode.

[0082] Figure 4 A schematic diagram of the operating status of the host and slave provided by the present invention, Figure 5 The schematic diagram of the working process of the host and slave provided by the present invention. Figure 4 and Figure 5 There are two working modes for the host and the slave, including asynchronous mode and synchronous mode. In normal working state, the asynchronous mode is adopted, and the host and the slave interact with each other in an asynchronous master-slave query mode. In the asynchronous mode, both the host and the slave use their own running clocks to collect and analyze data in an asynchronous manner.

[0083] S22, when the preset conditions are met, the system enters the synchronization mode, which includes the timing synchronization mode and the burst synchronization mode; in the synchronization mode, high-precision time synchronization between the host and the slave is achieved by sending a specific mode switching command and an IO hard pulse sequence.

[0084] Specifically, refer to Figure 4 and Figure 5 The synchronization mode includes the scheduled synchronization mode and the burst synchronization mode. The scheduled mode starts the synchronization operation and completes the time calibration within the agreed time period, which can ensure that the deviation of its own clock is within the controllable range. The burst mode is to obtain the abnormal situation in real time according to the set threshold, which can ensure the absolute synchronization accuracy in the case of specific faults (determined according to the set threshold).

[0085] In step S22, the workflow of the timing synchronization mode includes: when the cycle time ΔT of the timing synchronization mode is reached, the system automatically enters the timing synchronization mode: the host issues a mode switching command to notify all slaves to switch modes; the host and slaves then enter a silent state to receive and process synchronization signals; the host sends an IO hard pulse sequence to each slave, and the port corresponding to the slave is in interrupt mode at this time to ensure that the time of the host and all channel slaves is in a high-precision synchronization state; in the timing synchronization mode, the system will start a full synchronization acquisition, which is achieved through high-precision timing to ensure that the time of all data acquisition points is completely consistent. During the data acquisition process, all data acquisitions are collected in a high-speed, evenly spaced continuous acquisition method, and the acquisition process can obtain a synchronized data set of two sections of AC and the residual current measurement values ​​of each loop.

[0086] Figure 6A schematic diagram of the synchronization process of the host and the slave provided by the present invention, in a preferred embodiment of the present invention, combined with Figure 4~Figure 6 , the working process of the timing synchronization mode is specifically described: In the actual operation process, when the cycle time ΔT of the timing mode is reached, the timing mode is entered. At this time, the host issues a mode switching command CMD1 and broadcasts it to all channels. At the same time, the host enters the silent state. At this time, the host silent time is t w1 , the host TX pin is switched from communication function to IO mode and set to output. When each slave receives the mode switching broadcast command CMD1, it enters the silent state. At this time, the slave silent time is t w2 , and t w2 >t w1 , the slave RX pin is changed from the communication function to the IO mode, set to input, and is in edge interrupt mode to ensure that the slave can respond in time when the host sends a hardware synchronization pulse. After the host is silent, all slaves in each channel are also in silence. The host sends an IO hard pulse sequence. This sequence can be modified according to the needs of time synchronization, such as: single pulse PPS, IRIG-B code, custom pulse sequence, etc., to ensure that the time of the host and all channel slaves is in a high-precision synchronization state (us level). When the pulse sequence synchronization is completed, it enters the synchronous acquisition stage. At this time, the host collects the electrical parameters of the two sections of low-voltage AC cables to determine the phase reference basis of the two sections of AC, and the slave collects the corresponding residual current measurement value or other extended data. During the acquisition process, all data acquisition uses high-speed equal-interval continuous acquisition method, such as: single cycle (20ms) acquisition of 256 points, etc., in order to carry out FFT calculation and analysis and subsequent vector synthesis. When the timing synchronization is completed, it switches to asynchronous mode and the data is uploaded asynchronously. The synchronization process is as follows Figure 6 shown.

[0087] In step S22, the workflow of the burst synchronization mode includes: in the asynchronous mode, when the data collected by the slave exceeds the set threshold, the system enters the burst synchronization mode. In the burst synchronization mode, after the timing synchronization, the token batch data transmission method based on time division multiple access is adopted to allocate a time window to the slave of each channel, and each slave uses the slave address of the local machine as a token to upload the data collected synchronously in turn.

[0088] Reference Figure 5 The burst mode mode switching command is CMD2. The burst mode is based on the timing mode. After the timing synchronization, the token batch data transmission based on time division multiple access is added. That is, after the synchronous acquisition is completed, the time window t is allocated to each slave of the channel according to the agreed time of the master and slave. nj Each slave uses its own slave address as a token and uploads all the data collected synchronously in turn. Figure 7The token batch transmission process provided by the present invention is a schematic diagram. Compared with the traditional asynchronous master-slave query mode, the token batch transmission method can ensure that all data within this time section are uploaded to the host in real time, so as to carry out subsequent vector synthesis and data mining.

[0089] Figure 8 The schematic diagram of high-precision synchronization and batch data transmission of multiple channels and multiple units provided by the present invention can be expanded to the following based on the master-slave working mode based on a single channel provided in the above embodiment: Figure 8 The multi-channel multi-unit high-precision synchronization and bulk data transmission process is shown.

[0090] The present invention is based on high-precision synchronous acquisition of multiple channels and multiple detection units, improves the detection capacity and scale, and reduces the residual current calculation error caused by the synchronization time difference and the error caused by the difference in two phases.

[0091] It can be understood that the present invention realizes efficient reuse of existing communication lines by combining the switching of asynchronous and synchronous modes. Specifically, under normal working conditions, the host and the slave perform data interaction in an asynchronous master-slave query mode through the existing communication lines. At this time, the communication lines are mainly used to transmit data and control commands. When it is necessary to enter the synchronous mode, the host sends a mode switching command (such as CMD1 or CMD2) to all slaves through the communication line. This command informs the slave that it is about to enter the synchronous state and is ready to receive the synchronization signal. Since this synchronization signal is sent through the existing communication line, no additional hardware is required to transmit the synchronization signal. After receiving the synchronization pulse, the host and the slave start to collect data in a high-precision synchronous manner. After the acquisition is completed, the data can be uploaded to the host in an asynchronous manner through the existing communication line, or uploaded in a token batch data transmission mode in burst mode. In this way, the present invention realizes the multiplexing of the existing communication lines for the transmission of synchronization signals and high-precision synchronization acquisition without increasing the cost of additional hardware. This not only simplifies the topology of the system, but also reduces the cost and wiring difficulty.

[0092] Step S3, according to the synchronous data sets collected by the host and the slave, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, the residual current measurement value collected by the slave is translated and vector synthesized to obtain the residual current vector value of each loop.

[0093] It should be noted that in step S2, the slave collects the residual current measurement value of each loop on a single loop or feeder segment. The residual current measurement value is the part where the vector sum of the current of each phase line and the neutral line is not zero, reflecting the current imbalance of the specific loop or feeder segment, that is, the difference between the current flowing into and out of the cable segment. However, referring to Figure 3 When the present invention involves complex scenarios such as dual power supply common neutral line loops, collecting the residual current of each loop separately may not be enough to fully understand the current status of the entire system. This is because there may be current interaction and shunting between different loops, especially when the neutral lines are connected in parallel.

[0094] Therefore, in step S3, it is necessary to perform vector synthesis on the residual current of each circuit collected by the slave. This process takes into account factors such as the direction, magnitude, and phase angle of the current. By calculating the phase angle of all data in the same reference system, and translating and calculating based on the phase angle reference system of two sections of low-voltage AC cables, the residual current vector value of each circuit in the system is obtained. Through vector synthesis, more accurate and comprehensive residual current information can be obtained, thereby better supporting the monitoring, analysis, and troubleshooting of the power system.

[0095] Fig. 9 This is a schematic diagram of the residual current measurement of each circuit of two low-voltage AC cables provided by the present invention. Fig. 9 , Residual current of single-section feeder circuit in section I The grounding point is P3, and the residual current of the single-section feeder circuit of Section II is The grounding point is P4, the residual current of the single-section long feeder loop of Section I and The grounding point is P5, and the residual current of the single-section long feeder loop of Section II is and The grounding point is P6, and the residual current of the neutral line circuit of section I and section II is and The grounding point is P0.

[0096] After the electrical parameters of the two low-voltage AC cables and the residual current measurement values ​​of each circuit are collected in step S2, in step S3, the host performs vector synthesis calculation based on the two AC phase reference according to the data collected in step S2.

[0097] The vector synthesis calculation method of the present invention obtains the data collected synchronously by the host and the slave, calculates the phase angle of all data in the same reference system, and thereby realizes the translation and calculation of the phase angle reference system based on two sections of low-voltage AC cables. According to the section I / II attribute setting of the corresponding circuit in the host, the translation and calculation of the phase angle coordinate system of the corresponding circuit are adjusted; wherein, section I refers to section I low-voltage AC cable, and section II refers to section II low-voltage AC cable; for the circuit of section I, the A-phase voltage of section I is used as the zero vector reference basis; for the circuit of section II, the A-phase voltage of section II is used as the zero vector reference basis; for the common neutral line circuit, the A-phase voltage of section I or section II is used as the zero vector reference basis according to the operation status of section I / II of its switching device.

[0098] In a preferred embodiment of the present invention, in step S3, different vector synthesis calculation methods are used for different types of loops to calculate the residual current vector value of the corresponding loop.

[0099] Specifically, for the residual current vector value of the single-section feeder loop of section I and the single-section long feeder loop of section I, the phase A voltage of section I is used as the zero vector reference basis for translation calculation;

[0100] For the residual current vector value of the single-section feeder loop of section II and the single-section long feeder loop of section II, the phase A voltage of section II is used as the zero vector reference basis for translation calculation;

[0101] For the residual current vector value of the common neutral line loop, determine whether the loop belongs to section I or section II according to the commissioning status of the switching device. For the two residual current measurement values ​​in the common neutral line loop, and , respectively, taking the phase A voltage of the corresponding segment as the 0 vector reference basis for translation calculation, and calculating the translated and The vector synthesis value is used as the residual current vector value of the common neutral line loop.

[0102] Fig.10 The schematic diagram of the translation and calculation of the phase angle reference system of two sections of low-voltage AC cables provided by the present invention is as follows: Fig.11 The schematic diagram of the residual current vector synthesis based on the phase angle reference system of two sections of low-voltage AC cables provided by the present invention. Fig.10 and Fig.11 In this embodiment, for the residual current measurement value of the single-section feeder loop of section I , with the voltage of phase A in section I It is a 0 vector, and after translation calculation, it becomes the corresponding residual current vector value.

[0103] For the residual current measurement value of the single-section feeder circuit of section II , with the phase A voltage of section II It is a 0 vector, and the corresponding residual current is obtained after translation calculation.

[0104] For the residual current measurement value of the single-section long feeder loop of Section I and , with the voltage of phase A in section I It is a 0 vector, calculated after translation and The vector synthesis value is the corresponding residual current.

[0105] For the residual current measurement value of the single-section long feeder loop of section II and , with the phase A voltage of section II It is a 0 vector, calculated after translation and The vector synthesis value is the corresponding residual current.

[0106] For the vector synthesis of the common neutral line loop, the residual current measurement value of the common neutral line loop between section I and section II and In addition to determining whether the corresponding circuit belongs to section Ⅰ or section Ⅱ, it is also necessary to determine the voltage of phase A in section Ⅰ according to the operation status of section Ⅰ or section Ⅱ of the switching device. The vector is 0 or the voltage of phase A in section II It is a 0 vector, calculated after translation and The vector synthesis value is the residual current of this common neutral line loop.

[0107] like Fig.10 As shown, based on the translation and calculation of the phase angle reference system of the two sections of low-voltage AC cables, X1 and X2 actually overlap. For the convenience of distinction, they are drawn separately to identify and distinguish the waveforms of Section I / Section II.

[0108] In this embodiment, refer to Fig.10 , the various parameters in the translation and calculation of the phase angle reference system based on two sections of low-voltage AC cables are specifically explained:

[0109] Synchronous signal reference system: (with the synchronous signal as the 0 vector and the origin as )

[0110] , , :A phase voltage, B phase voltage, C phase voltage of segment I

[0111] , , : Phase A voltage, phase B voltage, phase C voltage of segment II

[0112] : Residual current of section I feeder loop (dashed line in X1 axis)

[0113] : Residual current of the feeder circuit of section II (dashed line in the X2 axis)

[0114] :Section I reference system (with Section I A phase voltage The phase angle difference between the reference frame of the synchronous signal (with the synchronous signal as the 0 vector) and the reference frame of the synchronous signal (with the synchronous signal as the 0 vector) is

[0115] :Section II reference system (with Section II A phase voltage The phase angle difference between the reference frame of the synchronous signal (with the synchronous signal as the 0 vector) and the reference frame of the synchronous signal (with the synchronous signal as the 0 vector) is

[0116] :The phase angle of the feeder loop of section I in the synchronous signal reference system (with the synchronous signal as the 0 vector)

[0117] : The phase angle of the feeder loop of section II in the synchronous signal reference system (with the synchronous signal as the 0 vector)

[0118] definition:

[0119] :Section I feeder loop in Section I reference system (with Section I A phase voltage The phase angle of the vector is 0

[0120] :Section II feeder loop in section I reference system (with phase A voltage of section I) The phase angle of the vector is 0

[0121] :Section I feeder loop in section II reference system (with section II A phase voltage The phase angle of the vector is 0

[0122] :Section II feeder loop in section II reference system (with section II A phase voltage The phase angle of the vector is 0

[0123] Section I reference system (with Section I phase A voltage is the 0 vector, the origin is ), after the coordinate system is translated:

[0124] , ,

[0125] Section II reference system (with Section II A phase voltage is the 0 vector, the origin is ), after the coordinate system is translated:

[0126] ,

[0127] Reference Fig.11 , the various parameters and calculation formulas of the residual current vector synthesis based on the phase angle reference system of two sections of low-voltage AC cables are specifically explained:

[0128] Section I reference system: (with Section I A phase voltage is 0 vector)

[0129] :In the reference system of section I (with the voltage of phase A in section I 0 vector) Phase A voltage vector of segment I

[0130] :In the reference system of section I (with the voltage of phase A in section I 0 vector) Segment I B phase voltage vector

[0131] :In the reference system of section I (with the voltage of phase A in section I 0 vector) Segment I phase C voltage vector

[0132] :Section I feeder loop in Section I reference system (with Section I A phase voltage Residual current vector

[0133] :Section II feeder loop in section I reference system (with phase A voltage of section I) Residual current vector

[0134] :In the reference system of section I (with the voltage of phase A in section I The residual current vector after synthesis is 0 vector

[0135] :Section I feeder loop in Section I reference system (with Section I A phase voltage The phase angle of the vector is 0

[0136] :Section II feeder loop in section I reference system (with phase A voltage of section I) The phase angle of the vector is 0

[0137] The calculation formula for the residual current vector synthesis of the reference system of section I is:

[0138]

[0139] In the formula, represents the residual current vector after synthesis in the reference frame of section I, It represents the residual current vector of the feeder loop of section I in the reference system of section I, It represents the residual current vector of the feeder loop of section II in the reference frame of section I, It represents the phase angle of the feeder loop of section I in the reference system of section I, It represents the phase angle of the feeder loop of section II in the reference system of section I.

[0140] Section II reference system: (with Section II A phase voltage is 0 vector)

[0141] : In the reference system of section II (with the voltage of phase A in section II 0 vector) Phase A voltage vector of section II

[0142] : In the reference system of section II (with the voltage of phase A in section II 0 vector) Phase B voltage vector of section II

[0143] : In the reference system of section II (with the voltage of phase A in section II 0 vector) Phase C voltage vector of section II

[0144] :Section I feeder loop in section II reference system (with section II A phase voltage Residual current vector

[0145] :Section II feeder loop in section II reference system (with section II A phase voltage Residual current vector

[0146] : In the reference system of section II (with the voltage of phase A in section II The residual current vector after synthesis is 0 vector

[0147] :Section I feeder loop in section II reference system (with section II A phase voltage The phase angle of the vector is 0

[0148] :Section II feeder loop in section II reference system (with section II A phase voltage The phase angle of the vector is 0

[0149] The calculation formula for the residual current vector synthesis of the reference system of section II is:

[0150]

[0151] In the formula, represents the residual current vector after synthesis in the reference frame of section II, It represents the phase angle of the feeder loop of section I in the reference system of section II, It represents the residual current vector of the feeder loop of section II in the reference system of section II, It represents the phase angle of the feeder loop of section I in the reference system of section II, It represents the phase angle of the section II feeder loop in the section II reference system.

[0152] Reference Fig.10 and Fig.11 , the vector synthesis and calculation methods of various types of feeder loops in section I low-voltage AC cable and section II low-voltage AC cable are as follows:

[0153] For the residual current measurement value of the single-section feeder loop of Section I , that is ,and is empty, with the voltage of phase A in section I It is a 0 vector, and according to the above formula, it can be translated and calculated to obtain the corresponding residual current vector value.

[0154] For the residual current measurement value of the single-section feeder circuit of section II , that is ,and is empty, with the phase A voltage of section II It is a 0 vector, and according to the above formula, it can be translated and calculated to obtain the corresponding residual current vector value.

[0155] For the residual current measurement value of the single-section long feeder loop of Section I and , that is ,and On the X1 axis, the voltage of phase A in segment I is a 0 vector, which can be calculated by translation according to the above formula and The vector synthesis value is the corresponding residual current vector value.

[0156] For the residual current measurement value of the single-section long feeder loop of section II and , that is ,and On the X2 axis, the voltage of phase A in section II is a 0 vector, which can be calculated by translation according to the above formula and The vector synthesis value is the corresponding residual current vector value.

[0157] The present invention adopts a residual current vector synthesis calculation method based on the phase angle reference system of two sections of low-voltage AC cables, which can accurately obtain the residual current of various types of loops. This method not only improves the accuracy of detection, but also has scalability, and can realize advanced analysis of the time section data of all parameters of the low-voltage AC power supply system.

[0158] Fig.12 The structural block diagram of the low-voltage AC cable residual current detection system for the station provided by the present invention is shown in FIG. Fig.12 The station low-voltage AC cable residual current detection system 1200 includes:

[0159] The detection system construction module 1201 is used to arrange a topological structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, and the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine the phase reference basis of the low-voltage AC cable; and the slave is used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system;

[0160] The data synchronization acquisition module 1202 is used for the host and the slave to acquire data by switching between asynchronous and synchronous modes to obtain a synchronous data set;

[0161] The calculation module 1203 is used to perform translation and vector synthesis calculation on the residual current measurement value collected by the slave according to the synchronous data sets collected by the host and the slave, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, to obtain the residual current vector value of each loop.

[0162] The station low-voltage AC cable residual current detection system provided by the present invention executes the station low-voltage AC cable residual current detection method provided by the above-mentioned embodiments through the above-mentioned modules. The station low-voltage AC cable residual current detection method has been described in detail in the above-mentioned embodiments, and this embodiment will not be repeated here.

[0163] Fig.13 The structural block diagram of the electronic device provided by the present invention is as follows: Fig.13 As shown, the present invention also provides an electronic device, and the electronic device 1300 can be a computing device such as a mobile terminal, a desktop computer, a notebook, a palm computer, and a server. The electronic device 1300 includes a processor 1301 and a memory 1302, wherein the memory 1302 stores a station low-voltage AC cable residual current detection program 1303.

[0164] In some embodiments, the memory 1302 may be an internal storage unit of a computer device, such as a hard disk or memory of the computer device. In other embodiments, the memory 1302 may also be an external storage device of a computer device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device. Furthermore, the memory 1302 may also include both an internal storage unit and an external storage device of the computer device. The memory 1302 is used to store application software and various types of data installed on the computer device, such as program codes installed on the computer device. The memory 1302 may also be used to temporarily store data that has been output or is to be output. In one embodiment, when the station low-voltage AC cable residual current detection program 1303 is executed by the processor 1301, the following steps are implemented:

[0165] S1, arranging a topological structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine a phase reference basis of the low-voltage AC cables; the slaves are used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system;

[0166] S2, the master and slave collect data by switching between asynchronous and synchronous modes to obtain a synchronized data set;

[0167] S3, according to the synchronous data sets collected by the master and slaves, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, the residual current measurement values ​​collected by the slaves are translated and vector synthesized to obtain the residual current vector value of each loop.

[0168] In some embodiments, the processor 1301 may be a central processing unit (CPU), a microprocessor or other data processing chip, used to run program codes or process data stored in the memory 1302, such as executing a station-use low-voltage AC cable residual current detection program.

[0169] This embodiment further provides a computer-readable storage medium, on which a station low-voltage AC cable residual current detection program is stored. When the station low-voltage AC cable residual current detection program is executed by a processor, the following steps are implemented:

[0170] S1, arranging a topological structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine a phase reference basis of the low-voltage AC cables; the slaves are used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system;

[0171] S2, the master and slave collect data by switching between asynchronous and synchronous modes to obtain a synchronized data set;

[0172] S3, according to the synchronous data sets collected by the master and slaves, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, the residual current measurement values ​​collected by the slaves are translated and vector synthesized to obtain the residual current vector value of each loop.

[0173] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0174] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting residual current of a low-voltage AC cable for a station, characterized in that: include: S1, arranging a topological structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine a phase reference basis of the low-voltage AC cables; the slaves are used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system; S2, the host and the slave collect data by switching between asynchronous and synchronous modes to obtain a synchronous data set; including: S21, the system uses asynchronous mode to collect data during normal operation, and the host and the slave interact with each other in an asynchronous master-slave query mode; S22, when the preset conditions are met, the system enters the synchronization mode, which includes the timing synchronization mode and the burst synchronization mode; in the synchronization mode, high-precision time synchronization between the host and the slave is achieved by sending a specific mode switching command and an IO hard pulse sequence; In step S22, the workflow of the timing synchronization mode includes: When the periodic synchronization mode reaches its ΔT, the system automatically enters the timing synchronization mode: The host issues a mode switching command to notify all slaves to switch modes; The master and slave then enter a silent state in order to receive and process the synchronization signal; The host sends an IO hard pulse sequence to each slave, and the corresponding port of the slave is in interrupt mode to ensure that the time of the host and all channel slaves is in high-precision synchronization; Both the host and slave use high-speed equal-interval continuous acquisition mode for data acquisition; S3, according to the synchronous data sets collected by the master and slaves, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, the residual current measurement values ​​collected by the slaves are translated and vector synthesized to obtain the residual current vector value of each loop; The method of performing translation and vector synthesis calculation on the residual current measurement value collected by the slave based on the cable segment to which the loop belongs and the corresponding phase reference basis includes: Obtain data collected synchronously by the host and slave, and calculate the phase angle of the data in the same reference system; According to the section I / section II property setting of the corresponding circuit in the host, the translation and calculation of the phase angle coordinate system of the corresponding circuit are adjusted; wherein section I refers to section I low-voltage AC cable, section II refers to section II low-voltage AC cable, and the low-voltage AC power supply system includes section I low-voltage AC cable and section II low-voltage AC cable; For the circuit of section I, the phase A voltage of section I is used as the zero vector reference basis; for the circuit of section II, the phase A voltage of section II is used as the zero vector reference basis; for the circuit of common neutral line, the phase A voltage of section I or section II is used as the zero vector reference basis when the switching device is in the operation state of section I / section II; In step S3, the method for calculating the residual current vector value of each loop includes: For different types of loops, different vector synthesis calculation methods are used to calculate the residual current vector value of the corresponding loop; wherein the types of the loops include single-section feeder loops, single-section long feeder loops and common neutral line loops; For the residual current vector value of the single-section feeder loop of section I and the single-section long feeder loop of section I, the phase A voltage of section I is used as the zero vector reference basis for translation calculation; For the residual current vector value of the single-section feeder loop of section II and the single-section long feeder loop of section II, the phase A voltage of section II is used as the zero vector reference basis for translation calculation; For the residual current vector value of the common neutral line loop, determine whether the loop belongs to section I or section II according to the commissioning status of the switching device. For the two residual current measurement values ​​in the common neutral line loop, and , respectively, taking the phase A voltage of the corresponding segment as the 0 vector reference basis for translation calculation, and calculating the translated and The vector synthesis value is used as the residual current vector value of the common neutral line loop; In step S3, the residual current vector synthesis calculation formula based on the phase angle reference system of the two low-voltage AC cables includes: The calculation formula for the residual current vector synthesis of the reference system of section I is: In the formula, represents the residual current vector after synthesis in the reference frame of section I, It represents the residual current vector of the feeder loop of section I in the reference system of section I, It represents the residual current vector of the feeder loop of section II in the reference frame of section I, It represents the phase angle of the feeder loop of section I in the reference system of section I, It represents the phase angle of the feeder loop of section II in the reference system of section I; The calculation formula for the residual current vector synthesis of the reference system of section II is: In the formula, represents the residual current vector after synthesis in the reference frame of section II, It represents the phase angle of the feeder loop of section I in the reference system of section II, It represents the residual current vector of the feeder loop of section II in the reference system of section II, It represents the phase angle of the feeder loop of section I in the reference system of section II, It represents the phase angle of the section II feeder loop in the section II reference system.

2. The method for detecting residual current of a low-voltage AC cable for a station according to claim 1, characterized in that: In step S22, the workflow of the burst synchronization mode includes: In asynchronous mode, when the data collected by the slave exceeds the set threshold, the system enters burst synchronization mode; In burst synchronization mode, after timing synchronization, a token batch data transmission method based on time division multiple access is adopted to allocate a time window for the slaves of each channel. Each slave uses its own slave address as a token to upload the data collected in this synchronization in turn.

3. A system using the station low-voltage AC cable residual current detection method as claimed in claim 1 or 2, characterized in that: include: A detection system building module is used to arrange a topology structure including a host and multiple slaves in a low-voltage AC power supply system; wherein the host is connected to each slave through multiple channels, and the host is used to collect electrical parameters of two sections of low-voltage AC cables in the low-voltage AC power supply system to determine a phase reference basis of the low-voltage AC cable; and the slave is used to collect residual current measurement values ​​of each circuit in the low-voltage AC power supply system; The data synchronization acquisition module is used for the host and the slave to acquire data by switching between asynchronous and synchronous modes to obtain a synchronous data set; The calculation module is used to translate and vector synthesize the residual current measurement values ​​collected by the slave according to the synchronous data sets collected by the host and the slave, for different types of loops in the system, based on the cable segment to which the loop belongs and the corresponding phase reference basis, to obtain the residual current vector value of each loop.

4. An electronic device, It is characterized in that comprising a memory and a processor, wherein: The memory is used to store programs; The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the station low-voltage AC cable residual current detection method described in claim 1 or 2.

5. A computer-readable storage medium, characterized in that: Used to store computer-readable programs or instructions, which, when executed by a processor, can implement the steps of the station low-voltage AC cable residual current detection method described in claim 1 or 2.

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