Single-frequency interference detection method, power terminal two-way communication system and method

Abstract

The invention belongs to the technical field of wireless communication, and relates to a single-frequency interference detection method, a power terminal two-way communication system and a power terminal two-way communication method. Sampling each symbol period in a received signal on a wireless channel at a preset sampling frequency to obtain a plurality of sampling sequences; accumulating each li data groups in each sampling sequence to obtain a target sampling sequence; performing FFT conversion on each target sampling sequence, and calculating an FFT complex modulus value of the converted target sampling sequence and a frequency spectrum characteristic function of a received signal; if the frequency spectrum characteristic function is smaller than or equal to the threshold value, determining that the wireless channel is a non-interference channel; if the spectral characteristic function is larger than a threshold value, i is updated to be equal to i + 1, each li data packet in each target sampling sequence is accumulated, the target sampling sequences are updated, FFT is carried out again until the resolution of single-frequency interference detection reaches a preset resolution, the wireless channel is judged to be an interference channel, and the detection efficiency and reliability are both considered.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a single-frequency interference detection method, a power terminal two-way communication system and method. Background Art

[0002] The concentrator, photovoltaic protocol converter and photovoltaic communication converter in the photovoltaic system are usually installed by wired connection. For application scenarios where the photovoltaic inverter is far away from the grid connection point, the photovoltaic protocol converter is often installed on the roof and the power is taken from the IoT meter in front of the grid connection point downstairs. This results in the need for long cables for construction, which is costly and unsightly, and may cause opposition from photovoltaic users. In addition, after the wired installation, the photovoltaic inverter and the photovoltaic protocol converter will be fixedly bound, and the requirements of flexible networking cannot be achieved by modifying the configuration of the photovoltaic protocol converter, which increases the subsequent maintenance cost. Although the use of wireless communication can avoid the cable cost and maintenance cost problems brought by wired communication, there will be single-frequency interference on the wireless channel during wireless communication, which will affect the stability and reliability of the communication between the concentrator, photovoltaic protocol converter and photovoltaic communication converter. Therefore, solving the impact of single-frequency interference on the wireless communication between the concentrator, photovoltaic protocol converter and photovoltaic communication converter is an urgent problem to be solved.

[0003] Single-frequency interference is a type of electromagnetic interference linearity. Since the center frequency of the interference signal coincides with or is close to the center frequency of the useful signal, it interferes with the useful signal in the frequency domain. This interference has the characteristics of narrow spectrum, concentrated signal energy and good interference effect. Once the single-frequency interference signal enters the passband of the receiver, it will cause blockage, making the receiver unable to work normally, resulting in reduced communication quality or communication interruption. Therefore, when conducting wireless communication, it is usually necessary to perform single-frequency interference detection on each wireless channel to screen out non-interference channels for communication to avoid the impact of single-frequency interference on communication quality and reliability.

[0004] The single-frequency interference detection method in the prior art converts the analog signal received on the wireless channel into a digital signal, performs a fast Fourier transform (FFT) on the digital signal, and thus converts the signal from the time domain to the frequency domain. The FFT can decompose the signal into sine waves of different frequencies, and give the amplitude and phase information of each frequency component. By searching the peak value of each frequency component, if there is a peak value of a frequency component greater than a preset threshold or much greater than the peak value of other frequency components, it is determined that there is single-frequency interference on the transmission channel, and the channel is used as an interference channel. However, when performing FFT transformation on the signal, the number of FFT points (i.e., the amount of data to be transformed) and the sampling rate determine the frequency resolution and the detectable frequency range. A higher FFT point number and sampling rate will improve the frequency resolution, and can more accurately identify the specific frequency components in the signal, so that the single-frequency interference detection result is more accurate. However, the higher the number of FFT points, the greater the amount of calculation and the complexity of operation, resulting in a longer single-frequency interference detection time, a lower detection efficiency, and the inability to meet the real-time requirements.

[0005] In summary, the existing single-frequency interference detection method cannot take into account both the reliability and efficiency of the detection results, resulting in the inability to solve the impact of single-frequency interference on the wireless communication between the concentrator, photovoltaic protocol converter and photovoltaic communication converter, and thus the inability to ensure the stability of wireless communication in the photovoltaic system. Summary of the invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the problem that the single-frequency interference detection method in the prior art cannot take into account both the reliability and efficiency of the detection results, resulting in the inability to solve the impact of single-frequency interference on the wireless communication between the concentrator, the photovoltaic protocol converter and the photovoltaic communication converter, and thus the inability to ensure the stability of the wireless communication of the photovoltaic system.

[0007] In order to solve the above technical problems, the present invention provides a single-frequency interference detection method, comprising:

[0008] S10: sampling each symbol period of the signal received by the receiving end of the wireless channel to be detected at a preset sampling frequency to obtain sampling sequences corresponding to different symbol periods;

[0009] S20: Initialize i=1, and set each l in each sampling sequence i The data are grouped and accumulated to obtain the target sampling sequence corresponding to each symbol period; where N is l i A multiple of , N is the number of data in the sampling sequence;

[0010] S30: performing FFT transformation on each target sampling sequence respectively, and performing complex conjugate square on the target sampling sequence after FFT transformation to obtain the FFT complex modulus value of the target sampling sequence;

[0011] S40: performing non-coherent accumulation of the FFT complex modulus values ​​of all target sampling sequences to obtain a spectrum characteristic function of the signal;

[0012] S50: determining whether the value of the spectrum characteristic function is greater than a threshold value, and if the value of the spectrum characteristic function is less than or equal to the threshold value, determining that the wireless channel to be detected is a non-interference channel;

[0013] S60: If the value of the spectrum characteristic function is greater than the threshold value, it is determined whether the frequency resolution of the current single-frequency interference detection reaches the preset resolution. If the frequency resolution of the current single-frequency interference detection does not reach the preset resolution, i=i+1 is updated, and each l in each target sampling sequence is updated. i The data are grouped and accumulated, the target sampling sequence is updated, and the step S30 is returned to be executed until the frequency resolution of the single-frequency interference detection reaches the preset resolution, and the wireless channel to be detected is determined to be an interference channel; wherein N / (l1×l2×...×l i-1 ) is l i multiples of.

[0014] Preferably, after sampling each symbol period of the signal received by the receiving end of the wireless channel to be detected at a preset sampling frequency, the method further includes frequency shifting the sampled data at a preset shift frequency.

[0015] Preferably, after updating the target sampling sequence in step S60, the step further includes:

[0016] Acquire the current single-frequency interference frequency, and use the sum of the current single-frequency interference frequency and the preset shift frequency as the target shift frequency;

[0017] The data in the updated target sampling sequence is frequency shifted at the target shift frequency.

[0018] Preferably, the formula for performing FFT transformation on each target sampling sequence is:

[0019]

[0020] in, represents the tth target sampling sequence after FFT transformation, represents the tth target sampling sequence, p represents the sequence number of the time domain sampling point, and k represents the sequence number of the frequency domain subcarrier;

[0021] The calculation formula for the FFT complex modulus value of the target sampling sequence is:

[0022]

[0023] in, It represents the FFT complex modulus value of the t-th target sampling sequence, and * represents the complex conjugate.

[0024] The present invention also provides a two-way communication system for power terminals, comprising:

[0025] A plurality of dual-mode communication modules are respectively deployed on each photovoltaic protocol converter in the photovoltaic system, and networked with the dual-mode CCO on the concentrator in the photovoltaic system. The dual-mode communication module on each photovoltaic protocol converter establishes a connection with the wireless communication module on each photovoltaic communication converter in its connection list; wherein the dual-mode CCO on the concentrator uses the above-mentioned single-frequency interference detection method to perform single-frequency interference detection on each wireless channel between the dual-mode communication module and the dual-mode CCO, obtains a non-interference channel list, and randomly selects a wireless channel in the non-interference channel list as the target communication channel;

[0026] Multiple wireless communication modules are respectively deployed on the photovoltaic communication converters of each photovoltaic inverter in the photovoltaic system. The wireless communication module on each photovoltaic communication converter establishes a connection with the dual-mode communication module on its corresponding photovoltaic protocol converter, so that each photovoltaic communication converter can perform two-way communication with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter.

[0027] Preferably, the wireless communication module on each photovoltaic communication converter establishes a connection with the dual-mode communication module on its corresponding photovoltaic protocol converter, including:

[0028] The wireless communication module on the photovoltaic communication converter sends a search frame carrying the MAC address of the photovoltaic communication converter on each wireless channel;

[0029] After receiving the search frame, the dual-mode communication module on each photovoltaic protocol converter determines whether the photovoltaic communication converter MAC address carried by the search frame is in its connection list. If so, it continuously sends synchronization frames carrying the network number at a preset time interval;

[0030] After receiving the synchronization frame, the wireless communication module on the photovoltaic communication converter configures the same network number as the synchronization frame, thereby establishing a connection with the dual-mode communication module on the photovoltaic protocol converter.

[0031] Preferably, after the wireless communication module on the photovoltaic communication converter establishes a connection with the dual-mode communication module on the photovoltaic protocol converter, the method further includes:

[0032] The wireless communication module on the photovoltaic communication converter sends a heartbeat frame at a preset time interval. If the heartbeat frame fails to be sent, it is determined that the wireless communication module on the photovoltaic communication converter is disconnected from the dual-mode communication module on the photovoltaic protocol converter;

[0033] The wireless communication module on the photovoltaic communication converter re-sends the search frame carrying the MAC address of the photovoltaic communication converter on each wireless channel to re-establish the connection with the dual-mode communication module on the corresponding photovoltaic protocol converter.

[0034] Preferably, the photovoltaic communication converter performs bidirectional communication with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter, including:

[0035] The dual-mode communication module on the photovoltaic protocol converter receives the service frame carrying the MAC address of the photovoltaic communication converter sent by the dual-mode CCO on the concentrator, and broadcasts it on the target communication channel;

[0036] The wireless communication module on the photovoltaic communication converter connected to the dual-mode communication module on the photovoltaic protocol converter receives the service frame, and determines whether the photovoltaic communication converter MAC address carried by the service frame is the MAC address of the photovoltaic communication converter where it is located, and if so, performs a frame response;

[0037] The dual-mode communication module on the photovoltaic protocol converter sends a response frame to the dual-mode CCO on the concentrator based on the frame response.

[0038] Preferably, the communication priority between the dual-mode communication module on the photovoltaic protocol converter and the dual-mode CCO on the concentrator is higher than the communication priority between the dual-mode communication module on the photovoltaic protocol converter and the wireless communication module on the photovoltaic communication converter.

[0039] The present invention also provides a power terminal two-way communication method, which is applied to the above-mentioned power terminal two-way communication system, comprising:

[0040] Network the dual-mode communication modules on each photovoltaic protocol converter with the dual-mode CCO on the concentrator in the photovoltaic system;

[0041] The dual-mode CCO on the concentrator performs single-frequency interference detection on each wireless channel between the dual-mode communication module and the dual-mode CCO to obtain a non-interference channel list, and randomly selects a wireless channel from the non-interference channel list as a target communication channel;

[0042] A connection is established between the wireless communication module on each photovoltaic communication converter and the dual-mode communication module on its corresponding photovoltaic protocol converter, so that each photovoltaic communication converter can communicate bidirectionally with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter.

[0043] The single-frequency interference detection method provided by this application has the following beneficial effects:

[0044] 1. By sampling each symbol period of the signal received by the receiving end on the wireless channel, more data points can be obtained for single-frequency interference detection; at the same time, by sampling each l in each sampling sequence i The data are grouped and accumulated to obtain the target sampling sequence, and then the target sampling sequence is transformed by FFT. Under the premise of ensuring that the number of data points used for single-frequency interference detection is sufficient, the number of FFT operation points and the complexity of operation are reduced, thereby improving the detection efficiency. The spectrum characteristic function of the signal is obtained based on the FFT complex modulus value of all target sampling sequences, thereby judging whether the wireless channel is an interference channel. In addition, when the value of the spectrum characteristic function is less than or equal to the threshold value, the wireless channel is directly judged as a non-interference channel without the need for subsequent detection, thus saving detection time. When the value of the spectrum characteristic function is greater than the threshold value, it is also necessary to judge whether the frequency resolution of the current single-frequency interference detection reaches the preset resolution. If the preset resolution is not reached, i=i+1 is updated, and each l in each target sampling sequence is again updated. i The data are grouped and accumulated, the target sampling sequence is updated, and the next round of single-frequency interference detection is performed until the frequency resolution of the single-frequency interference detection reaches the preset resolution requirement, thereby determining that the wireless channel is an interference channel, thereby improving the reliability of the detection result; therefore, the single-frequency interference detection method provided by the present application can take into account both the detection efficiency and the reliability of the detection result;

[0045] 2. This application deploys a dual-mode communication module on the photovoltaic protocol converter in the photovoltaic system, and deploys a wireless communication module on the photovoltaic communication converter. The dual-mode CCO on the concentrator uses the single-frequency interference detection method provided by this application to perform single-frequency interference detection on the wireless channel in the photovoltaic system, which can accurately and timely screen out non-interference channels, so that the concentrator, photovoltaic protocol converter and photovoltaic communication converter can communicate on non-interference channels, thereby improving the communication stability and reliability between the concentrator, photovoltaic protocol converter and photovoltaic communication converter, avoiding the cable cost and maintenance cost problems brought by wired communication, and ensuring the stability of two-way communication in the photovoltaic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0047] Figure 1 A flow chart of the single-frequency interference detection method provided in this application;

[0048] Figure 2 A schematic diagram of the connection principle between the wireless communication module and the dual-mode communication module provided in this application;

[0049] Figure 3 A schematic diagram of the principle of two-way communication of power terminals provided for this application;

[0050] Figure 4 A flow chart of the two-way communication method for power terminals provided in this application. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0052] Example 1

[0053] See also Figure 1 , Figure 1 The figure shows a flow chart of a single-frequency interference detection method provided by the present application, which specifically includes:

[0054] S10: sampling each symbol period of the signal received by the receiving end of the wireless channel to be detected at a preset sampling frequency to obtain sampling sequences corresponding to different symbol periods;

[0055] S20: Initialize i=1, and set each l in each sampling sequence i The data are grouped and accumulated to obtain the target sampling sequence corresponding to each symbol period; where N is l i A multiple of , N is the number of data in the sampling sequence;

[0056] S30: performing FFT transformation on each target sampling sequence respectively, and performing complex conjugate square on the target sampling sequence after FFT transformation to obtain the FFT complex modulus value of the target sampling sequence;

[0057] S40: performing non-coherent accumulation of the FFT complex modulus values ​​of all target sampling sequences to obtain a spectrum characteristic function of the signal;

[0058] S50: determining whether the value of the spectrum characteristic function is greater than a threshold value, and if the value of the spectrum characteristic function is less than or equal to the threshold value, determining that the wireless channel to be detected is a non-interference channel;

[0059] S60: If the value of the spectrum characteristic function is greater than the threshold value, determine whether the frequency resolution of the current single-frequency interference detection reaches the preset resolution. If the frequency resolution of the current single-frequency interference detection does not reach the preset resolution, update i=i+1 and set each l in each target sampling sequence. i The data are grouped and accumulated, the target sampling sequence is updated, and the step S30 is returned to be executed until the frequency resolution of the single-frequency interference detection reaches the preset resolution, and the wireless channel to be detected is determined to be an interference channel; wherein N / (l1×l2×...×l i-1 ) is l i multiples of.

[0060] Specifically, when i=1, the frequency resolution of single-frequency interference detection is f s / l1, when i=2, the frequency resolution of the single-frequency interference detection frequency is f s / (l1×l2), therefore, with the increase of detection levels, the value of frequency resolution becomes smaller and smaller, which also means that the frequency resolution becomes higher and higher, that is, the detection accuracy becomes higher and higher.

[0061] The single-frequency interference detection method provided by the present application samples each symbol period of the signal received by the receiving end on the wireless channel to obtain more data points for single-frequency interference detection; at the same time, by sampling each l in each sampling sequence i The data are grouped and accumulated to obtain the target sampling sequence, and then the target sampling sequence is transformed by FFT. Under the premise of ensuring that the number of data points used for single-frequency interference detection is sufficient, the number of FFT operation points and the complexity of operation are reduced, thereby improving the detection efficiency. The spectrum characteristic function of the signal is obtained based on the FFT complex modulus value of all target sampling sequences, thereby judging whether the wireless channel is an interference channel. In addition, when the value of the spectrum characteristic function is less than or equal to the threshold value, the wireless channel is directly judged as a non-interference channel without the need for subsequent detection, thus saving detection time. When the value of the spectrum characteristic function is greater than the threshold value, it is also necessary to judge whether the frequency resolution of the current single-frequency interference detection reaches the preset resolution. If the preset resolution is not reached, i=i+1 is updated, and each l in each target sampling sequence is again updated. i The data are grouped and accumulated, the target sampling sequence is updated, and the next round of single-frequency interference detection is performed until the frequency resolution of the single-frequency interference detection reaches the preset resolution requirement, thereby determining that the wireless channel is an interference channel, thereby improving the reliability of the detection result; therefore, the single-frequency interference detection method provided in the present application can take into account both the detection efficiency and the reliability of the detection result.

[0062] Specifically, the formula for performing FFT transformation on each target sampling sequence in step S30 is:

[0063]

[0064] in, represents the tth target sampling sequence after FFT transformation, represents the tth target sampling sequence, p represents the sequence number of the time domain sampling point, and k represents the sequence number of the frequency domain subcarrier;

[0065] The calculation formula for the FFT complex modulus value of the target sampling sequence is:

[0066]

[0067] in, It represents the FFT complex modulus value of the t-th target sampling sequence, and * represents the complex conjugate.

[0068] The frequency spectrum characteristic function of the signal in step S40 is expressed as:

[0069]

[0070] in, represents the spectrum characteristic function of the received signal, and T represents the number of target sampling sequences;

[0071] Further, the threshold value in step S60 is expressed as:

[0072] Y_thr=Thr*Yall,

[0073]

[0074] Wherein, Thr represents a threshold decision parameter. In a specific example of the present application, the value of Thr is 0.3.

[0075] Optionally, in order to more effectively identify the interference signal, the single-frequency interference signal is moved to a specific position of the spectrum to make it more prominent relative to other signal components, and after sampling each symbol period of the signal received by the receiving end of the wireless channel to be detected at a preset sampling frequency, the method also includes frequency shifting the sampled data at a preset shift frequency, which is expressed as follows:

[0076] x n =r n ·exp(-j2πf shift n / f s ),n=0,1,2,...,N t1 -1,

[0077] Among them, x n Represents the data after frequency shifting of the nth sampled data, r n Indicates the nth data obtained by sampling, f shiftIndicates the preset shift frequency, f s Indicates the preset sampling frequency, N t1 Indicates the number of data obtained by sampling;

[0078] Furthermore, after updating the target sampling sequence in step S60, the following steps are further included:

[0079] The current single-frequency interference frequency is obtained, and the sum of the current single-frequency interference frequency and the preset shift frequency is used as the target shift frequency; and the data in the updated target sampling sequence is frequency shifted at the target shift frequency.

[0080] Specifically, the target moving frequency is expressed as:

[0081] f′ shift =f shift +f int ,

[0082] Among them, f′ shift represents the target moving frequency, f int Indicates the current single-frequency interference frequency.

[0083] Example 2

[0084] With the popularization of the concept of ubiquitous Internet of Things and the rapid development of HPLC technology in recent years, the types and number of power terminals connected to the substation collection platform have also increased, from the previous simple remote meter reading meter terminal to the current derivative of new collectors, measurement units, intelligent circuit breakers, photovoltaic terminals, etc. Among them, taking distributed photovoltaic as an example, low-voltage distributed photovoltaic power generation has strong randomness and large volatility (power quality, voltage, current harmonics, etc.). Its large-scale grid connection has diversified the distribution entities and made the flow direction more complicated. The low-voltage substation distribution network will undergo significant changes in supply and demand balance, system regulation, and optimal operation. Therefore, it is necessary to install a photovoltaic protocol converter to achieve observable, measurable and controllable goals, flexibly control the photovoltaic inverter, and realize the precise scheduling of the photovoltaic system.

[0085] The existing photovoltaic protocol converter and the photovoltaic communication converter on the photovoltaic inverter are installed by wire. During the installation process, for application scenarios where the photovoltaic inverter is far away from the grid connection point, the photovoltaic protocol converter needs to be installed on the roof and power is taken from the IoT meter in front of the grid connection point downstairs. This results in the need for long cables for construction, which is costly and unsightly, and may cause opposition from photovoltaic users. In addition, after the installation of the wired network, the photovoltaic inverter and the photovoltaic protocol converter will be fixedly bound, and the requirements for flexible networking cannot be achieved by modifying the configuration of the photovoltaic protocol converter, which increases the subsequent maintenance costs. Therefore, due to the diversification of photovoltaic equipment and the complexity of application scenarios, any existing single-mode wired (power line) or RF wireless technology has limitations in practical applications.

[0086] Based on the above reasons, this application utilizes the advantages of the existing dual-mode acquisition system of the power grid with HPLC+HRF dual transmission channels, fully utilizes the characteristics of dual-mode heterogeneous networks and the characteristics and advantages of power line channels and wireless channels to achieve complementary advantages, and proposes a two-way communication system and method that can maintain multiple wireless photovoltaic communication converter nodes through HPLC / HRF networking in the uplink and repeated use of the HRF network in the downlink.

[0087] Specifically, the power terminal two-way communication system provided in the embodiment of the present application includes:

[0088] Multiple dual-mode communication modules are respectively deployed on each photovoltaic protocol converter in the photovoltaic system, and are networked with the dual-mode CCO on the concentrator in the photovoltaic system. The dual-mode communication module on each photovoltaic protocol converter establishes a connection with the wireless communication module on each photovoltaic communication converter in its connection list; wherein the dual-mode CCO on the concentrator uses the above-mentioned single-frequency interference detection method to perform single-frequency interference detection on each wireless channel between the dual-mode communication module and the dual-mode CCO, obtains a non-interference channel list, and randomly selects a wireless channel in the non-interference channel list as the target communication channel;

[0089] Multiple wireless communication modules are respectively deployed on the photovoltaic communication converters of each photovoltaic inverter in the photovoltaic system. The wireless communication module on each photovoltaic communication converter establishes a connection with the dual-mode communication module on its corresponding photovoltaic protocol converter, so that each photovoltaic communication converter can communicate bidirectionally with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter.

[0090] Specifically, Figure 2 As shown, the wireless communication module on each photovoltaic communication converter establishes a connection with the dual-mode communication module on its corresponding photovoltaic protocol converter, including:

[0091] The wireless communication module on the photovoltaic communication converter sends a search frame carrying the MAC address of the photovoltaic communication converter on each wireless channel;

[0092] After receiving the search frame, the dual-mode communication module on each photovoltaic protocol converter determines whether the photovoltaic communication converter MAC address carried in the search frame is in its connection list. If so, it continuously sends synchronization frames carrying the network number at a preset time interval;

[0093] After receiving the synchronization frame, the wireless communication module on the photovoltaic communication converter configures the same network number as the synchronization frame, thereby establishing a connection with the dual-mode communication module on the photovoltaic protocol converter.

[0094] In some embodiments, some preferred wireless channels may also be selected so that the wireless communication module on the photovoltaic communication converter preferentially searches on multiple preferred wireless channels, so as to quickly establish a connection with the dual-mode communication module on the photovoltaic protocol converter;

[0095] For example, the wireless communication module on the photovoltaic communication converter quickly switches different wireless channels, searching each wireless channel for 100ms, and it only takes 4 seconds to complete the search on 40 preferred wireless channels;

[0096] For example, continuously sending synchronization frames carrying network numbers at preset time intervals means that after the dual-mode communication module on the photovoltaic protocol converter determines that the MAC address of the photovoltaic communication converter carried by the search frame is in its connection list, it sends 5 synchronization frames at an interval of 100ms, then sends 5 synchronization frames at an interval of 2s, and then sends synchronization frames again at an interval of 30s.

[0097] Specifically, when the dual-mode communication module that has been networked replies to the synchronization frame, the network number is the network number of the current network, and when the dual-mode communication module that has not been networked replies to the synchronization frame, the network number is 0.

[0098] Preferably, after the wireless communication module on the photovoltaic communication converter establishes a connection with the dual-mode communication module on the photovoltaic protocol converter, the method further includes:

[0099] The wireless communication module on the photovoltaic communication converter sends a heartbeat frame at a preset time interval. If the heartbeat frame fails to be sent, it is determined that the wireless communication module on the photovoltaic communication converter is disconnected from the dual-mode communication module on the photovoltaic protocol converter;

[0100] The wireless communication module on the photovoltaic communication converter re-sends the search frame carrying the MAC address of the photovoltaic communication converter on each wireless channel to re-establish the connection with the dual-mode communication module on the corresponding photovoltaic protocol converter.

[0101] For example, after the wireless communication module establishes a connection with the dual-mode communication module on the photovoltaic communication protocol converter, it sends heartbeat detection frames in a cycle of 10 seconds. If the heartbeat detection frame fails to be sent, it means that the connection has failed, and the wireless communication module needs to re-establish a connection with the dual-mode communication module on the photovoltaic protocol converter.

[0102] Optionally, in some embodiments of the present application, the wireless communication module on the photovoltaic communication converter records the wireless channel of this communication after the connection is successful, and preferentially searches for the wireless channel that has been successfully connected when the connection is subsequently restarted.

[0103] Specifically, in some embodiments of the present application, the search frame forms a search frame structure by setting fields such as a delimiter type field, a network type field, a network identification field, a destination site address, a connection sequence number, and a frame control check sequence, wherein the delimiter type field is used to select a confirmation frame, and the specific configuration of each field can be selected according to actual needs;

[0104] In a specific application embodiment of the present application, the specific configuration of each field of the search frame is:

[0105] Network type: value 0, MPDU is transmitted in the power consumption information collection system;

[0106] Network ID: 0;

[0107] Destination site address: the destination address of the connection;

[0108] Connection sequence number: used to distinguish scenarios with multiple dual-mode communication modules. Search frames and synchronization frames are matched through connection sequence numbers. Different dual-mode communication modules use different connection sequence numbers.

[0109] Table 1 shows a search frame structure provided in an embodiment of the present application:

[0110] Table 1

[0111]

[0112]

[0113] In this embodiment, the synchronization frame specifically forms a synchronization frame structure by setting fields such as a delimiter type field, a network type field, a network identification field, a timestamp field, a STEI field, a wireless OPTION field, a wireless channel number field, and a connection sequence number field, wherein the networked dual-mode communication module configuration in the timestamp field does not send a network clock, and the unnetworked dual-mode communication module configuration does not send a local clock. The specific configuration of each field can also be selected according to actual needs;

[0114] In a specific application embodiment of the present application, the specific configuration of each field of the synchronization frame is:

[0115] Delimiter Type: Select Confirmation Frame;

[0116] Network type: value 0, MPDU is transmitted in the power consumption information collection system;

[0117] Network ID: The network ID of the dual-mode communication module that has been networked is the current network ID, and the network ID of the dual-mode communication module that has not been networked is 0;

[0118] Timestamp: The networked dual-mode communication module sends the network clock, and the unnetworked dual-mode communication module sends the local clock;

[0119] STEI: TEI address of the module to be connected. The STEI of the dual-mode communication module that is not networked is 0.

[0120] Wireless OPTION: This field is reserved and filled with 0;

[0121] Wireless channel number: This field is reserved.

[0122] Connection sequence number: used to distinguish multiple dual-mode communication module scenarios. Search frames and synchronization frames are matched through connection sequence numbers. Different dual-mode communication modules use different connection sequence numbers.

[0123] Extended frame type: The extended frame type of the wireless network search frame is 1, and the extended frame type of the synchronization frame is 2, to identify the frame type;

[0124] Table 2 shows a synchronization frame structure provided by an embodiment of the present application:

[0125] Table 2

[0126]

[0127] Specifically, the photovoltaic communication converter performs bidirectional communication with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter, including:

[0128] The dual-mode communication module on the photovoltaic protocol converter receives the service frame carrying the MAC address of the photovoltaic communication converter sent by the dual-mode CCO on the concentrator, and broadcasts it on the target communication channel;

[0129] The wireless communication module on the photovoltaic communication converter connected to the dual-mode communication module on the photovoltaic protocol converter receives the service frame, and determines whether the photovoltaic communication converter MAC address carried in the service frame is the MAC address of the photovoltaic communication converter where it is located. If so, a frame response is performed;

[0130] The dual-mode communication module on the photovoltaic protocol converter sends a response frame to the dual-mode CCO on the concentrator based on the framing response.

[0131] Specifically, the dual-mode communication module on the photovoltaic protocol converter monitors the wireless frames with its own communication purpose on the same wireless channel, receives and analyzes them one by one, and starts business processing according to different frames;

[0132] The dual-mode communication module carries the TEI of the dual-mode CCO during uplink communication (communication with the dual-mode CCO on the concentrator), and carries the TEI of the wireless communication module during downlink communication (communication with the wireless communication module on the photovoltaic communication converter). It also carries the MAC address of the photovoltaic communication converter where the wireless communication module is located.

[0133] In addition, the communication priority between the dual-mode communication module on the photovoltaic protocol converter and the dual-mode CCO on the concentrator is higher than the communication priority between the dual-mode communication module on the photovoltaic protocol converter and the wireless communication module on the photovoltaic communication converter. Therefore, when there are uplink communication frames in the data to be sent by the dual-mode communication module, the carrier channel will be tried first to send it. After successful transmission, the wireless frame of downlink communication will be sent on the wireless channel.

[0134] The embodiment of the present application designs a two-way communication system for power terminals, directly deploys wireless nodes in the photovoltaic communication converter on the photovoltaic inverter, and establishes a connection with the dual-mode communication module on the photovoltaic protocol converter through the HRF local networking method, eliminating the photovoltaic protocol converter equipment and the RS485 wired wiring between the photovoltaic protocol converter and the photovoltaic communication converter. The construction work and material cost, while making the connection relationship between the photovoltaic protocol converter and the photovoltaic inverter no longer fixedly bound by wire, but can be selected by configuring the file in the photovoltaic protocol converter. The specified communication interface converter connection. At the same time, wireless access technology will not be affected by complex interference in the power line channel, but the propagation of radio waves is easily affected by factors such as building obstruction, terrain, weather and metal shielding. In this regard, the existing simple Internet of Things wireless communication technologies such as FSK and GFSK have problems such as poor receiving sensitivity and obviously insufficient anti-interference performance, and cannot meet the complex and diverse needs of photovoltaic networking. Therefore, in the embodiment of the present application, the single-frequency interference detection technology provided in the above embodiment is used to detect the wireless channel, and the wireless channel is divided into a non-interference channel and an interference channel. By communicating in the non-interference channel, the influence of various single-frequency interferences on data transmission can be effectively avoided.

[0135] like Figure 3As shown is the schematic diagram of the two-way communication of the power terminal provided by the present application, a micro-power wireless communication module that meets the requirements of the State Grid HRF standard is extended in the photovoltaic communication converter. After the wireless communication module is powered on, the MAC address of the photovoltaic communication converter is used as its own communication address; the master station sends the MAC address of the photovoltaic communication converter that needs to be configured under the specified photovoltaic protocol converter to the concentrator via the Internet, and the dual-mode communication module on the photovoltaic protocol converter periodically queries the current configuration address and saves it to its own connection list, thereby completing the connection between the wireless communication module and the dual-mode communication module. During downlink communication, the photovoltaic protocol converter forwards the content that needs to be sent to the photovoltaic communication converter to the dual-mode communication module through the serial port using the 698.45 / Modbus protocol. The dual-mode communication module sends the content that needs to be forwarded to the wireless communication module on the photovoltaic communication converter wirelessly. The wireless communication module sends the parsed data to the photovoltaic communication converter through the serial port to complete the downlink communication; in the uplink communication, the wireless communication module receives the 698.45 / Modbus protocol data sent by the photovoltaic communication converter through the serial port, and sends the content that needs to be forwarded to the dual-mode communication module on the photovoltaic protocol converter wirelessly. After the dual-mode communication module completes the parsing, it sends it to the photovoltaic protocol converter through the serial port, and finally completes a round of two-way communication.

[0136] The present application also provides a two-way communication method for a power terminal, which is applied to the above-mentioned two-way communication system for a power terminal. Specifically, Figure 4 As shown, the method specifically includes:

[0137] S1: Networking the dual-mode communication modules on each photovoltaic protocol converter with the dual-mode CCO on the concentrator in the photovoltaic system;

[0138] S2: The dual-mode CCO on the concentrator performs single-frequency interference detection on each wireless channel between the dual-mode communication module and the dual-mode CCO, obtains a list of non-interference channels, and randomly selects a wireless channel from the list of non-interference channels as the target communication channel;

[0139] S3: Establish a connection between the wireless communication module on each photovoltaic communication converter and the dual-mode communication module on its corresponding photovoltaic protocol converter, so that each photovoltaic communication converter can communicate bidirectionally with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter.

[0140] The power terminal two-way communication system and method provided in the present application solve the problem that the wired communication solution is high in cost and is limited by distance and geographical factors, eliminating the maintenance and debugging of related cables. In an environment built through a local wireless network, it is only necessary to send a connection list to the photovoltaic protocol converter through the concentrator to update the connection relationship between the photovoltaic protocol converter and the photovoltaic communication converter. At the same time, by reusing the wireless technology in the dual-mode chip, there is no need to deploy additional wireless modules, thereby shortening the overall communication link.

[0141] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0142] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0143] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0144] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0145] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A single-frequency interference detection method, characterized in that: include: S10: sampling each symbol period of the signal received by the receiving end of the wireless channel to be detected at a preset sampling frequency to obtain sampling sequences corresponding to different symbol periods; S20: Initialize i=1, and set each l in each sampling sequence i The data are grouped and accumulated to obtain the target sampling sequence corresponding to each symbol period; where N is l i A multiple of , N is the number of data in the sampling sequence; S30: performing FFT transformation on each target sampling sequence respectively, and performing complex conjugate square on the target sampling sequence after FFT transformation to obtain the FFT complex modulus value of the target sampling sequence; S40: performing non-coherent accumulation of the FFT complex modulus values ​​of all target sampling sequences to obtain a spectrum characteristic function of the signal; S50: determining whether the value of the spectrum characteristic function is greater than a threshold value, and if the value of the spectrum characteristic function is less than or equal to the threshold value, determining that the wireless channel to be detected is a non-interference channel; S60: If the value of the spectrum characteristic function is greater than the threshold value, it is determined whether the frequency resolution of the current single-frequency interference detection reaches the preset resolution. If the frequency resolution of the current single-frequency interference detection does not reach the preset resolution, i=i+1 is updated, and each l in each target sampling sequence is updated. i The data are grouped and accumulated, the target sampling sequence is updated, and the step S30 is returned to be executed until the frequency resolution of the single-frequency interference detection reaches the preset resolution, and the wireless channel to be detected is determined to be an interference channel; wherein N / (l1×l2×...×l i-1 ) is l i multiples of.

2. The single-frequency interference detection method according to claim 1, characterized in that: After sampling each symbol period of the signal received by the receiving end of the wireless channel to be detected at a preset sampling frequency, the method further includes frequency shifting the sampled data at a preset shift frequency.

3. The single-frequency interference detection method according to claim 2, characterized in that: After the target sampling sequence is updated in step S60, the following steps are further included: Acquire the current single-frequency interference frequency, and use the sum of the current single-frequency interference frequency and the preset shift frequency as the target shift frequency; The data in the updated target sampling sequence is frequency shifted at the target shift frequency.

4. The single-frequency interference detection method according to claim 1, characterized in that: The formula for FFT transformation of each target sampling sequence is: in, represents the tth target sampling sequence after FFT transformation, represents the tth target sampling sequence, p represents the sequence number of the time domain sampling point, and k represents the sequence number of the frequency domain subcarrier; The calculation formula for the FFT complex modulus value of the target sampling sequence is: in, It represents the FFT complex modulus value of the t-th target sampling sequence, and * represents the complex conjugate.

5. A two-way communication system for power terminals, characterized in that: include: A plurality of dual-mode communication modules are respectively deployed on each photovoltaic protocol converter in the photovoltaic system, and are networked with the dual-mode CCO on the concentrator in the photovoltaic system. The dual-mode communication module on each photovoltaic protocol converter establishes a connection with the wireless communication module on each photovoltaic communication converter in its connection list; wherein the dual-mode CCO on the concentrator performs single-frequency interference detection on each wireless channel between the dual-mode communication module and the dual-mode CCO using the single-frequency interference detection method as described in any one of claims 1 to 4, obtains a non-interference channel list, and randomly selects a wireless channel from the non-interference channel list as the target communication channel; Multiple wireless communication modules are respectively deployed on the photovoltaic communication converters of each photovoltaic inverter in the photovoltaic system. The wireless communication module on each photovoltaic communication converter establishes a connection with the dual-mode communication module on its corresponding photovoltaic protocol converter, so that each photovoltaic communication converter can perform two-way communication with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter.

6. The power terminal two-way communication system according to claim 5, characterized in that: The wireless communication module on each photovoltaic communication converter establishes a connection with the dual-mode communication module on its corresponding photovoltaic protocol converter, including: The wireless communication module on the photovoltaic communication converter sends a search frame carrying the MAC address of the photovoltaic communication converter on each wireless channel; After receiving the search frame, the dual-mode communication module on each photovoltaic protocol converter determines whether the photovoltaic communication converter MAC address carried by the search frame is in its connection list. If so, it continuously sends synchronization frames carrying the network number at a preset time interval; After receiving the synchronization frame, the wireless communication module on the photovoltaic communication converter configures the same network number as the synchronization frame, thereby establishing a connection with the dual-mode communication module on the photovoltaic protocol converter.

7. The power terminal two-way communication system according to claim 6, characterized in that: After the wireless communication module on the photovoltaic communication converter establishes a connection with the dual-mode communication module on the photovoltaic protocol converter, the following steps are also included: The wireless communication module on the photovoltaic communication converter sends a heartbeat frame at a preset time interval. If the heartbeat frame fails to be sent, it is determined that the wireless communication module on the photovoltaic communication converter is disconnected from the dual-mode communication module on the photovoltaic protocol converter; The wireless communication module on the photovoltaic communication converter re-sends the search frame carrying the MAC address of the photovoltaic communication converter on each wireless channel to re-establish the connection with the dual-mode communication module on the corresponding photovoltaic protocol converter.

8. The power terminal two-way communication system according to claim 5, characterized in that: The photovoltaic communication converter performs bidirectional communication on the target communication channel with the dual-mode CCO on the concentrator through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter, including: The dual-mode communication module on the photovoltaic protocol converter receives the service frame carrying the MAC address of the photovoltaic communication converter sent by the dual-mode CCO on the concentrator, and broadcasts it on the target communication channel; The wireless communication module on the photovoltaic communication converter connected to the dual-mode communication module on the photovoltaic protocol converter receives the service frame, and determines whether the photovoltaic communication converter MAC address carried by the service frame is the MAC address of the photovoltaic communication converter where it is located, and if so, performs a frame response; The dual-mode communication module on the photovoltaic protocol converter sends a response frame to the dual-mode CCO on the concentrator based on the frame response.

9. The power terminal two-way communication system according to claim 5, characterized in that: The communication priority between the dual-mode communication module on the photovoltaic protocol converter and the dual-mode CCO on the concentrator is higher than the communication priority between the dual-mode communication module on the photovoltaic protocol converter and the wireless communication module on the photovoltaic communication converter.

10. A two-way communication method for a power terminal, characterized in that: The two-way communication system for power terminals according to any one of claims 5 to 9 comprises: Network the dual-mode communication modules on each photovoltaic protocol converter with the dual-mode CCO on the concentrator in the photovoltaic system; The dual-mode CCO on the concentrator performs single-frequency interference detection on each wireless channel between the dual-mode communication module and the dual-mode CCO to obtain a non-interference channel list, and randomly selects a wireless channel from the non-interference channel list as a target communication channel; A connection is established between the wireless communication module on each photovoltaic communication converter and the dual-mode communication module on its corresponding photovoltaic protocol converter, so that each photovoltaic communication converter can communicate bidirectionally with the dual-mode CCO on the concentrator on the target communication channel through the wireless communication module and the dual-mode communication module on the photovoltaic protocol converter.

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