A method, system and controller for PLC carrier frequency identification of photovoltaic module shutdown device

Abstract

The application belongs to the technical field of switch-off device control, and particularly relates to a switch-off device for a photovoltaic module PLC Carrier frequency identification method, system and controller, compared with the traditional FFT Algorithm, because not using multiply and divide instructions, save a lot of CPU Time, users can therefore choose lower end CPU Compared with the method of using timer count rising edge, because it is with pre-calculated level average as the criterion of rising edge, not subject to the input pin of single-chip microcomputer timer to the level requirement, and has good anti-interference ability to some abnormal level jump; because using the cumulative value of difference as the filtering threshold, further improve the anti-interference ability of the algorithm.

Description

Technical Field

[0001] The present invention belongs to the technical field of circuit breaker control, and in particular relates to a PLC carrier frequency identification method, system and controller for a photovoltaic module circuit breaker. Background Art

[0002] A photovoltaic system consists of multiple PV panels connected in series to form a string. These panels are then connected to an inverter that converts high-voltage DC power to AC power for grid connection. In certain scenarios, such as fires, it's necessary to quickly shut down the PV panels to avoid the danger of high DC power flowing through the string.

[0003] The SunSpec Alliance has defined a communication format for shutoff and power-on commands between inverters and photovoltaic panels. A transmitter is installed on the inverter, and a circuit breaker is installed on the panel. PLC communication is used between the two. FSK uses two different frequencies, Fm: 131.25 kHz and Fs: 143.75 kHz, to represent different code elements. Different combinations of these code elements then form different commands. Therefore, correctly identifying the two different carrier frequencies becomes a critical issue for the circuit breaker. Currently, FFT algorithms can be used for frequency identification. While they offer relatively accurate results, they require a high number of sampling points and, consequently, high MCU computing power, particularly for multiplication and division operations. Consequently, their cost is relatively high. Alternatively, mature solutions from foreign manufacturers can be purchased, but this also carries significant cost pressures and increases delivery uncertainty.

[0004] Therefore, based on the above technical problems, it is necessary to design a new method, system and controller for PLC carrier frequency identification of photovoltaic module shutdown device. Summary of the Invention

[0005] The object of the present invention is to provide a method, system and controller for identifying the PLC carrier frequency of a photovoltaic module switch.

[0006] In order to solve the above technical problems, the present invention provides a PLC carrier frequency identification method for a photovoltaic module circuit breaker, comprising:

[0007] Sampling level data of at least one complete transmission cycle of the PLC signal to calculate an average value of the level signal of the complete transmission cycle and an average value of differences between each level data and the average value of the level signal in the complete transmission cycle;

[0008] The signal transmission interval and the quiet interval in the complete transmission cycle are distinguished according to the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle, so as to calculate the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval;

[0009] Set the sampling interval and sample the level data within one symbol time. Calculate the total number of rising edges based on the level signal average value of the complete transmission cycle, the average value of the difference between each level data and the level signal average value in the complete transmission cycle, the level signal average value of the signal transmission interval, and the level signal average value of the quiet interval.

[0010] The PLC signal carrier frequency is determined to be Fm or Fs based on the total number of rising edges.

[0011] Furthermore, the method for sampling level data of at least one complete transmission cycle in the PLC signal includes:

[0012] S1: With T1 as the period, sample the level data Voltage[i] (i∈[0, a-1]) of a point;

[0013] S2: Calculate the average value of a level data in this group and assign the average value to an array member:

[0014]

[0015] gAverage[index]=fAverage;

[0016] S3: Calculate the average of the absolute values ​​of the differences between the a level data in this group and the corresponding average value, and assign it to an array member:

[0017]

[0018] gDeviationRaw[index]=fDevAve;

[0019] S4: Repeat S1 to S3 b times so that the index increases from 0 to b-1, so as to sample the level data of at least one complete transmission cycle.

[0020] Further, S5: the average value of the level signal of the complete transmission cycle is calculated as:

[0021]

[0022] The average value of the difference between each level data and the average value of the level signal in the complete transmission cycle is calculated as:

[0023]

[0024] Further, S6: the signal transmission interval and the quiet interval in the complete transmission cycle are distinguished, and the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval are calculated respectively.

[0025] The average value of the level signal in the signal transmission interval is:

[0026] gSigDeviation=(∑gDeviationRaw[index]) / m, and

[0027] gDeviationRaw[index] takes the part where gDeviationRaw[index]>gDevRawAve, totaling m points;

[0028] The average value of the level signal in the quiet interval is:

[0029] gZeroDeviation=(∑gDeviationRaw[index]) / (bm).

[0030] Further, S7: set the sampling frequency to T2, and sample c points to obtain an array Voltage[x] (x∈[0, c-1]).

[0031] Further, S8: calculate the average value of the difference between the array Voltage[x] (x∈[0, c-1]) and the average value of the level signal of the complete transmission cycle:

[0032]

[0033] Determine whether the value is in the signal transmission range:

[0034] Determine fDeviationAve>(gZeroDeviation*K), where K is an empirical coefficient.

[0035] Further, S9: If the judgment condition of S8 is established, start counting the number of rising edges in this group of data. When (Voltage[x]<gMidVolADFactor)&&(gMidVolADFactor<Voltage[x+1]) is satisfied, that is,

[0036] If one rising edge is captured, the total number of rising edges captured in this group of data is n.

[0037] Furthermore, S9 is repeated several times to calculate the total number of rising edges as N;

[0038] If N belongs to the interval (Fm_MIN, Fm_MAX), the carrier frequency is Fm;

[0039] If N belongs to the interval (Fs_MIN, Fs_MAX), the carrier frequency is Fs.

[0040] In a second aspect, the present invention further provides a PLC controller for a photovoltaic module switch, comprising:

[0041] The PLC controller is adapted to sample the level data of at least one complete transmission cycle of the PLC signal to calculate the average value of the level signal of the complete transmission cycle and the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle;

[0042] The PLC controller is adapted to distinguish the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle to calculate the average value of the level signal of the signal transmission interval and the average value of the level signal of the quiet interval;

[0043] The PLC controller is adapted to set a sampling interval and sample the level data in one symbol time, and calculate the total number of rising edges according to the average value of the level signal of the complete transmission cycle, the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle, the average value of the level signal of the signal transmission interval and the average value of the level signal of the quiet interval;

[0044] The PLC controller is adapted to judge whether the carrier frequency of the PLC signal is Fm or Fs according to the total number of rising edges.

[0045] In a third aspect, the present application further provides a PLC carrier frequency identification system for a photovoltaic module shutdown device, comprising:

[0046] A sampling module is configured to sample the level data of at least one complete transmission cycle of the PLC signal to calculate the average value of the level signal of the complete transmission cycle and the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle;

[0047] A calculation module is configured to distinguish the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle to calculate the average value of the level signal of the signal transmission interval and the average value of the level signal of the quiet interval;

[0048] A statistics module is configured to set a sampling interval and sample the level data in one symbol time, and calculate the total number of rising edges according to the average value of the level signal of the complete transmission cycle, the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle, the average value of the level signal of the signal transmission interval and the average value of the level signal of the quiet interval;

[0049] A judgment module is configured to judge whether the carrier frequency of the PLC signal is Fm or Fs according to the total number of rising edges.

[0050] The beneficial effects of the present invention are as follows: the present invention samples the level data of at least one complete transmission cycle in the PLC signal to calculate the level signal average value of the complete transmission cycle and the average value of the difference between each level data and the level signal average value in the complete transmission cycle; the signal transmission interval and the quiet interval in the complete transmission cycle are distinguished according to the average value of the difference between each level data and the level signal average value in the complete transmission cycle to calculate the level signal average value of the signal transmission interval and the level signal average value of the quiet interval; a sampling interval is set, and the level data within a code element time is sampled, and the level signal average value of the complete transmission cycle and the level signal average value of the level data in the complete transmission cycle are calculated according to the level signal average value The total number of rising edges is calculated by the average value of the difference between them, the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval; the PLC signal carrier frequency is judged as Fm or Fs according to the total number of rising edges. Compared with the traditional FFT algorithm, since no multiplication and division instructions are used, a lot of CPU time is saved, so users can choose a lower-end CPU. Compared with the method of using a timer to count rising edges, since the pre-calculated level average value is used as the criterion for rising edges, it is not subject to the level requirements of the input pin of the microcontroller timer, and has good anti-interference ability for some abnormal level jumps; since the accumulated value of the difference is used as the filtering threshold, the anti-interference ability of the algorithm is further improved.

[0051] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 This is a workflow diagram of the PLC carrier frequency identification method for a photovoltaic module switch of the present invention;

[0055] Figure 2 This is a structural diagram of a carrier circuit of a PLC carrier frequency identification method for a photovoltaic module switch of the present invention;

[0056] Figure 3 It is a transmission message diagram of the PLC signal of the present invention;

[0057] Figure 4 It is a waveform diagram of the signal transmission interval and the quiet interval in a complete transmission cycle of the present invention;

[0058] Figure 5 The present invention is an algorithm flow chart of a PLC carrier frequency identification method for a photovoltaic module switch. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0060] Example 1

[0061] like Figures 1 to 5 As shown, this embodiment 1 provides a PLC carrier frequency identification method for a photovoltaic module switch, comprising: sampling level data of at least one complete transmission cycle in a PLC signal to calculate the level signal average value of the complete transmission cycle and the average value of the difference between each level data and the level signal average value in the complete transmission cycle; distinguishing the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the difference between each level data and the level signal average value in the complete transmission cycle to calculate the level signal average value of the signal transmission interval and the level signal average value of the quiet interval; setting a sampling interval and sampling level data within a symbol time, and calculating the level signal average value of the signal transmission interval and the level signal average value of the quiet interval according to the level signal average value of the complete transmission cycle and the level signal average value of the level data in the complete transmission cycle. The total number of rising edges is calculated by the average value of the difference between the data and the average value of the level signal, the average value of the level signal in the signal transmission interval, and the average value of the level signal in the quiet interval; the PLC signal carrier frequency is judged as Fm or Fs based on the total number of rising edges. Compared with the traditional FFT algorithm, since no multiplication and division instructions are used, a lot of CPU time is saved, so users can choose a lower-end CPU. Compared with the method of using a timer to count rising edges, since the pre-calculated level average value is used as the criterion for rising edges, it is not subject to the level requirements of the input pin of the microcontroller timer, and has good anti-interference ability for some abnormal level jumps; since the accumulated value of the difference is used as the filtering threshold, the anti-interference ability of the algorithm is further improved.

[0062] In the embodiment, the carrier circuit structure of the PLC carrier frequency identification method for the photovoltaic module shutdown device can be: the shutdown device takes power from the photovoltaic panel, and a DC-DC generates 3.3V voltage to supply power to the MCU (PLC controller) and the amplifier; the shutdown device obtains the PLC signal from the output DC loop through a coupling transformer, and sends the signal to the A / D port of the MCU (PLC controller) after filtering and amplification; the MCU (PLC controller) decodes the PLC signal, and if the control code is W1 W1 W1 defined in the SUNSPEC specification, the drive circuit controls the main switch to be turned on, otherwise the main switch is turned off, and the main switch is a MOSFET with low internal resistance; when the photovoltaic module is shaded, the shutdown device outputs through a bypass diode.

[0063] In the embodiment, as shown in Figures 3 and 4 , according to the definition of the SUNSPEC specification, the transmission message of the PLC signal is as shown in Figure 3 , wherein a complete transmission cycle includes an Active interval and a Zero Energy interval, wherein the Active interval is a signal transmission interval, the duration is 168.96ms, the Zero Energy is a quiet interval, the duration is 901.12ms, and the total duration of a complete transmission cycle is 1070.08ms. The actual waveform can be directly observed by an oscilloscope as shown in Figure 4 , and it can be seen that the level amplitude of the signal transmission interval is obviously higher than that of the quiet interval.

[0064] In the embodiment, the method for sampling the level data of at least one complete transmission cycle in the PLC signal includes:

[0065] S1: sampling the level data Voltage[i] (i∈[0, a-1]) of a points with T1 as the period; as an optional implementation, T1 is 20us, and a is 1000, that is, S1 occupies 20ms in total;

[0066] S2: calculating the average value of the a level data, and assigning the average value to an array member:

[0067]

[0068] gAverage[index]=fAverage;

[0069] As an optional implementation, the average value of the 1000 level data is calculated, and the average value is assigned to an array member, that is,

[0070] gAverage[index]=fAverage;

[0071] S3: Calculate the average of the absolute values ​​of the differences between the a level data in this group and the corresponding average value, and assign it to an array member:

[0072]

[0073] gDeviationRaw[index]=fDevAve; As an optional implementation, calculate the average of the absolute values ​​of the differences between the 1000 level data in this group and the corresponding average value, and assign it to an array member, that is,

[0074] gDeviationRaw[index]=fDevAve;

[0075] S4: Repeat S1 to S3 b times to increase index from 0 to b-1 to sample the level data of at least one complete transmission cycle. As an optional implementation, b is 60, and S4 takes a total of 1200ms, which can ensure that a complete transmission cycle of 1070.08ms is covered. Sampling the level data of at least one complete transmission cycle can ensure data integrity, facilitate the accuracy of the results in subsequent data processing, and ensure the accuracy of the final judgment of whether the PLC signal carrier frequency is Fm or Fs.

[0076] In this embodiment, S5: calculating the average value of the level signal of the complete transmission cycle is:

[0077]

[0078] The average value of the difference between each level data and the average value of the level signal in the complete transmission cycle is calculated as:

[0079]

[0080] As an optional implementation, the average value of the level signal of a complete transmission cycle is calculated as:

[0081]

[0082] The average value of the difference between each level data and the average value of the level signal in a complete transmission cycle is calculated as:

[0083]

[0084] In this embodiment, S6: the signal transmission interval and the quiet interval in the complete transmission cycle are distinguished, and the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval are calculated respectively.

[0085] The average value of the level signal in the signal transmission interval is:

[0086] gSigDeviation=(∑gDeviationRaw[index]) / m, and

[0087] gDeviationRaw[index] takes the part where gDeviationRaw[index]>gDevRawAve, totaling m points;

[0088] The average value of the level signal in the quiet interval is:

[0089] gZeroDeviation=(∑gDeviationRaw[index]) / (bm), that is

[0090] gZeroDeviation=(∑gDeviationRaw[index]) / (60-m).

[0091] In this embodiment, S7: set the sampling frequency to T2, and sample c points to obtain an array Voltage[x](x∈[0,c-1]); as an optional implementation, T2 takes 2us and c takes 20, and an array Voltage[x](x∈[0,19]) can be obtained; S1-6 is a priori process in the carrier frequency identification process. After completion, the formal carrier frequency identification process is entered.

[0092] In this embodiment, S8: Calculate the average value of the difference between the array Voltage[x] (x∈[0, c-1]) and the average value of the level signal of the complete transmission cycle:

[0093]

[0094] Determine whether the value is in the signal transmission range:

[0095] Determine fDeviationAve>(gZeroDeviation*K), where K is an empirical coefficient.

[0096] As an optional implementation, the average value of the difference between the array Voltage[x] (x∈[0,19]) and the average value of the level signal of the complete transmission cycle, that is,

[0097] It is determined whether the value is in the signal transmission range, that is, it is determined whether fDeviationAve>(gZeroDeviation*K), where K is an empirical coefficient.

[0098] In this embodiment, S9: If the judgment condition of S8 is met, then start counting the number of rising edges in this group of data. When (Voltage[x]<gMidVolADFactor)&&(gMidVolADFactor<Voltage[x+1]) is satisfied, that is,

[0099] If a rising edge is captured, the total number of rising edges captured in this group of data is n. The pre-calculated level average value is used as the criterion for the rising edge. It is not subject to the level requirements of the input pin of the microcontroller timer, and has good anti-interference ability for some abnormal level jumps.

[0100] In this embodiment, S9 is repeated several times to calculate the total number of rising edges to be N. As an optional implementation, S9 is repeated 127 times, that is, S9 is a total of 5120 μs, which is exactly the duration of one symbol.

[0101] If N belongs to the interval (Fm_MIN, Fm_MAX), the carrier frequency is Fm;

[0102] If N belongs to the interval (Fs_MIN, Fs_MAX), the carrier frequency is Fs.

[0103] In this embodiment, if Figure 5 As shown, first, level data exceeding one complete transmission cycle is sampled, and the average level signal is calculated. The average level signal of the signal transmission interval and the average level signal of the quiet interval are also calculated. The signal-to-noise ratio is calculated based on the average level signal of the signal transmission interval and the average level signal of the quiet interval. If the signal-to-noise ratio is higher than a preset value, the sampling interval is set to between 1 / 4 and 1 / 3 of the cycle of the signal to be measured, and 20 points are sampled. At the same time, the sum of the differences between this group of data and the average value is calculated. If the sum is greater than a preset threshold value, then when the first point of two adjacent points in the sampled signal is less than the average value and the second point is greater than the average value, the number of rising edges is increased by 1, and the number is continuously executed for the duration of one code element to obtain the total number of rising edges. If the number of rising edges matches the number of the frequency defined by the standard within the duration of one code element, the received signal frequency is the target frequency. Otherwise, the received signal frequency is not the target frequency.

[0104] Example 2

[0105] Based on Example 1, this Example 2 further provides a PLC controller for a photovoltaic module switch, including:

[0106] The PLC controller is suitable for sampling the level data of at least one complete transmission cycle in the PLC signal to calculate the level signal average value of the complete transmission cycle and the average value of the difference between each level data and the level signal average value in the complete transmission cycle; the PLC controller is suitable for distinguishing the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the difference between each level data and the level signal average value in the complete transmission cycle to calculate the level signal average value of the signal transmission interval and the level signal average value of the quiet interval; the PLC controller is suitable for setting a sampling interval and sampling the level data within a code element time, and calculating the total number of rising edges according to the level signal average value of the complete transmission cycle, the average value of the difference between each level data and the level signal average value in the complete transmission cycle, the level signal average value of the signal transmission interval and the level signal average value of the quiet interval; the PLC controller is suitable for judging whether the PLC signal carrier frequency is Fm or Fs based on the total number of rising edges; the specific functions and implementation methods of the PLC controller have been described in detail in Example 1 and will not be repeated here.

[0107] Example 3

[0108] Based on Example 1, this Example 2 further provides a PLC carrier frequency identification system for a photovoltaic module circuit breaker, including:

[0109] a sampling module for sampling level data of at least one complete transmission cycle of the PLC signal to calculate an average value of the level signal of the complete transmission cycle and an average value of differences between each level data and the average value of the level signal in the complete transmission cycle;

[0110] a calculation module, which distinguishes the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the difference between each level data and the level signal average value in the complete transmission cycle, so as to calculate the level signal average value of the signal transmission interval and the level signal average value of the quiet interval;

[0111] The statistics module sets a sampling interval and samples the level data within one symbol time, and calculates the total number of rising edges based on the level signal average value of the complete transmission cycle, the average value of the difference between each level data and the level signal average value in the complete transmission cycle, the level signal average value of the signal transmission interval, and the level signal average value of the quiet interval;

[0112] The judgment module judges whether the PLC signal carrier frequency is Fm or Fs according to the total number of rising edges; the specific functions and implementation methods of each module have been described in detail in Example 1 and will not be repeated here.

[0113] In summary, the present invention samples the level data of at least one complete transmission cycle in the PLC signal to calculate the level signal average value of the complete transmission cycle and the average value of the difference between each level data and the level signal average value in the complete transmission cycle; the signal transmission interval and the quiet interval in the complete transmission cycle are distinguished according to the average value of the difference between each level data and the level signal average value in the complete transmission cycle to calculate the level signal average value of the signal transmission interval and the level signal average value of the quiet interval; a sampling interval is set, and the level data within a code element time is sampled, and the level signal average value of the complete transmission cycle and the difference between each level data and the level signal average value in the complete transmission cycle are distinguished according to the average value of the level signal of the complete transmission cycle and the difference between each level data and the level signal average value in the complete transmission cycle are distinguished according to the average value of the level signal of the complete transmission cycle and the difference between The total number of rising edges is calculated by the average value of the value, the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval; the PLC signal carrier frequency is judged as Fm or Fs according to the total number of rising edges. Compared with the traditional FFT algorithm, since no multiplication and division instructions are used, a lot of CPU time is saved, so users can choose a lower-end CPU. Compared with the method of using a timer to count rising edges, since the pre-calculated level average value is used as the criterion for rising edges, it is not subject to the level requirements of the input pin of the microcontroller timer, and has good anti-interference ability for some abnormal level jumps; since the accumulated value of the difference is used as the filtering threshold, the anti-interference ability of the algorithm is further improved.

[0114] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a portion of code, and the module, program segment or a portion of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0115] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0116] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the method S described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0117] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A PLC carrier frequency identification method for a photovoltaic module switch, characterized in that: include: Sampling level data of at least one complete transmission cycle of the PLC signal to calculate an average value of the level signal of the complete transmission cycle and an average value of differences between each level data and the average value of the level signal in the complete transmission cycle; The signal transmission interval and the quiet interval in the complete transmission cycle are distinguished according to the average value of the difference between each level data and the average value of the level signal in the complete transmission cycle, so as to calculate the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval; Set the sampling interval and sample the level data within one symbol time. Calculate the total number of rising edges based on the level signal average value of the complete transmission cycle, the average value of the difference between each level data and the level signal average value in the complete transmission cycle, the level signal average value of the signal transmission interval, and the level signal average value of the quiet interval. Determine whether the PLC signal carrier frequency is Fm or Fs based on the total number of rising edges; The method for sampling level data of at least one complete transmission cycle in a PLC signal comprises: S1: With T1 as the period, sample the level data Voltage[i] (i∈[0, a-1]) of a point; S2: Calculate the average value of a level data in this group and assign the average value to an array member: gAverage[index]=fAverage; S3: Calculate the average of the absolute values ​​of the differences between the a level data in this group and the corresponding average value, and assign it to an array member: gDeviationRaw[index]=fDevAve; S4: Repeat S1 to S3 b times so that the index increases from 0 to b-1, so as to sample the level data of at least one complete transmission cycle.

2. The PLC carrier frequency identification method for a photovoltaic module switch according to claim 1, characterized in that: S5: The average value of the level signal of the complete transmission cycle is calculated as: The average value of the difference between each level data and the average value of the level signal in the complete transmission cycle is calculated as:

3. The PLC carrier frequency identification method for a photovoltaic module switch according to claim 2, wherein: S6: the signal transmission interval and the quiet interval in the complete transmission cycle are distinguished, and the average value of the level signal in the signal transmission interval and the average value of the level signal in the quiet interval are calculated respectively. The average value of the level signal in the signal transmission interval is: gSigDeviation=(∑gDeviationRaw[index]) / m, and gDeviationRaw[index] takes the part where gDeviationRaw[index]>gDevRawAve, totaling m points; The average value of the level signal in the quiet interval is: gZeroDeviation=(∑gDeviationRaw[index]) / (bm).

4. The PLC carrier frequency identification method for a photovoltaic module switch according to claim 3, characterized in that: S7: Set the sampling frequency to T2 and sample c points to obtain an array Voltage[x] (x ∈ [0, c - 1]).

5. The PLC carrier frequency identification method for a photovoltaic module disconnector according to claim 4, wherein S8: Calculate the average value of the difference between the array Voltage[x] (x ∈ [0, c - 1]) and the average value of the level signals in a complete transmission cycle: Determine whether this value is within the signal transmission interval: Determine whether fDeviationAve > (gZeroDeviation * K), where K is an empirical coefficient.

6. The PLC carrier frequency identification method for a photovoltaic module disconnector according to claim 5, wherein S9: If the judgment condition in S8 holds, start counting the number of rising edges in this group of data. When (Voltage[x] < gMidVolADFactor) && (gMidVolADFactor < Voltage[x + 1]), that is a rising edge is captured, and the total number of rising edges captured in this group of data is n.

7. The PLC carrier frequency identification method for a photovoltaic module disconnector according to claim 6, wherein Repeat S9 several times to calculate the total number of rising edges as N; If N belongs to the interval (Fm_MIN, Fm_MAX), the carrier frequency is Fm; If N belongs to the interval (Fs_MIN, Fs_MAX), the carrier frequency is Fs.

8. A PLC controller for a photovoltaic module switch, characterized in that: Comprising: The PLC controller is adapted to sample the level data of at least one complete transmission cycle in the PLC signal to calculate the average value of the level signals in the complete transmission cycle and the average value of the differences between each level data in the complete transmission cycle and the average value of the level signals; The PLC controller is adapted to distinguish the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the differences between each level data in the complete transmission cycle and the average value of the level signals, so as to calculate the average value of the level signals in the signal transmission interval and the average value of the level signals in the quiet interval; The PLC controller is adapted to set the sampling interval and sample the level data within one symbol time, and calculate the total number of rising edges according to the average value of the level signals in the complete transmission cycle, the average value of the differences between each level data in the complete transmission cycle and the average value of the level signals, the average value of the level signals in the signal transmission interval, and the average value of the level signals in the quiet interval; The PLC controller is adapted to determine whether the PLC signal carrier frequency is Fm or Fs according to the total number of rising edges.

9. A PLC carrier frequency identification system for photovoltaic module switch, characterized in that: Comprising: A sampling module that samples the level data of at least one complete transmission cycle in the PLC signal to calculate the average value of the level signals in the complete transmission cycle and the average value of the differences between each level data in the complete transmission cycle and the average value of the level signals; A calculation module that distinguishes the signal transmission interval and the quiet interval in the complete transmission cycle according to the average value of the differences between each level data in the complete transmission cycle and the average value of the level signals, so as to calculate the average value of the level signals in the signal transmission interval and the average value of the level signals in the quiet interval; The statistics module sets a sampling interval and samples the level data within one symbol time, and calculates the total number of rising edges based on the level signal average value of the complete transmission cycle, the average value of the difference between each level data and the level signal average value in the complete transmission cycle, the level signal average value of the signal transmission interval, and the level signal average value of the quiet interval; The judgment module judges whether the PLC signal carrier frequency is Fm or Fs according to the total number of rising edges.

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