A Composite Communication System for Photovoltaic Optimizers Based on Lora and PLC and Its Working Method

Abstract

A photovoltaic optimizer composite communication system based on Lora and PLC and its working method disclosed by the present invention belong to the technical field of photovoltaic power generation. The detection unit of the power optimizer can collect the electrical parameter data of photovoltaic modules in real time, communicate between the upper computer and the photovoltaic optimizer through the Lora communication module, and communicate between photovoltaic optimizers through the PLC communication module. Through the Lora communication module and the PLC communication module, the upper computer can grasp the actual operation status of each photovoltaic module in the photovoltaic system in real time, determine the position information of the photovoltaic module through the unique identification ID of the photovoltaic optimizer, and then issue control instructions according to the actual operation status to adjust the working mode of the photovoltaic optimizer to ensure the normal operation of the photovoltaic module. The composite communication system of the present invention combines the two, without the need to build an additional communication network, effectively reducing costs and improving the reliability and stability of communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic optimizer communication, and particularly relates to a composite communication system for photovoltaic optimizers based on Lora and PLC and its working method. Background Art

[0002] A photovoltaic optimizer can achieve maximum power point tracking (MPPT) for each photovoltaic module, ensuring that each photovoltaic module in the photovoltaic system can output electrical energy to the maximum extent. It also has functions of energy transmission, energy optimization, data acquisition, and communication, and is suitable for use in areas with severe shading on mountains and roofs.

[0003] Currently, the communication methods of photovoltaic optimizers are relatively single, generally using wired communication methods such as RS485 communication, bus communication, power line carrier PLC communication, or wireless communication method Lora technology. The RS485 communication and bus communication methods are simple, but they require laying a communication network, increasing the construction cost. The power line carrier PLC communication eliminates the communication line and can communicate with a power line, but in a DC system circuit, the ground capacitance is large and the filtering effect is significant, and the carrier signal attenuates rapidly with distance. Increasing the transmission power will affect the power generation efficiency. The wireless communication Lora technology is small in size, strong in performance, and has strong environmental adaptability, suitable for outdoor work, but it cannot solve the positioning problem of photovoltaic optimizers in the system, cannot determine which two adjacent photovoltaic optimizers are connected, and has a high wireless communication delay, unable to meet the communication problems between adjacent optimizers and the system's rapid issuance of command information to all photovoltaic optimizers in the system. Summary of the Invention

[0004] In order to solve the above existing problems, the purpose of the present invention is to provide a composite communication system for photovoltaic optimizers based on Lora and PLC and its working method, which can locate the position of each photovoltaic optimizer in the system, does not require additional construction of a communication network, has low cost, good real-time communication, high reliability, and high stability.

[0005] The present invention is realized through the following technical solutions:

[0006] The present invention discloses a composite communication system for photovoltaic optimizers based on Lora and PLC, including photovoltaic optimizers connected to each photovoltaic module in the photovoltaic system. The input end of the photovoltaic optimizer is connected to the corresponding photovoltaic module, and the output end is connected in series with other photovoltaic optimizers;

[0007] The photovoltaic optimizer includes a processing unit and a power conversion unit. The power conversion unit is respectively connected to the processing unit and the photovoltaic module, and detection units are connected to both the input end and the output end of the power conversion unit; the processing unit is also connected to a Lora communication module and a PLC communication module;

[0008] The PV optimizer is connected to the host computer through the Lora communication module and is connected to the PLC communication modules of other PV optimizers through the PLC communication module. Each PV optimizer has a unique identification ID.

[0009] Preferably, the power conversion unit includes a boost synchronous rectification circuit.

[0010] Preferably, the detection unit includes two shunt monitors for detecting the input and output currents of the power conversion unit and two voltage dividers for detecting the input and output voltages of the power conversion unit.

[0011] Preferably, the host computer includes a Lora data acquisition module, a data processing module, and a storage module; the Lora data acquisition module is communicatively interconnected with the Lora communication module, the Lora data acquisition module is connected to the data processing module, and the data processing module is connected to the storage module.

[0012] Preferably, the antennas of the Lora communication module and the PLC communication module are fixed on the outer wall of the PV optimizer housing without contact.

[0013] Further preferably, the PV optimizer housing is a non-metallic housing.

[0014] The present invention discloses a working method of the above PV optimizer composite communication system based on Lora and PLC, including: when the host computer needs to collect data of a string of PV optimizers, the position information of the string of PV optimizers is confirmed according to the unique identification ID of the PV optimizer. The host computer issues an instruction to the Lora communication modules of all PV optimizers in the string of PV optimizers. The detection unit collects the electrical parameter data at the input and output ends of the power conversion unit and sends the electrical parameter data to the PLC communication module of the adjacent PV optimizer through the PLC communication module; the processing unit of each PV optimizer in the string of PV optimizers sorts the electrical parameter data of the present PV optimizer and the electrical parameter data of the adjacent PV optimizer, and uploads them to the host computer through the Lora communication module in turn; the host computer analyzes and processes all the electrical parameter data uploaded by the string of PV optimizers, and compares the electrical parameter data of each PV optimizer at the same moment with the electrical parameter data of this PV optimizer received by the adjacent PV optimizer. If the comparison is consistent, the data is considered reliable and recorded; if the comparison is inconsistent, the data is considered unreliable and not recorded;

[0015] When the host computer sends an instruction, the host computer sends the instruction to the Lora communication module of a certain PV optimizer. After receiving the instruction, the PV optimizer sends the instruction to the Lora communication module of the adjacent PV optimizer through the PLC communication module until all PV optimizers receive the instruction sent by the host computer, and all PV optimizers change the operation mode according to the instruction sent by the host computer.

[0016] Preferably, the sorting of the electrical parameter data is performed according to the importance requirements of different electrical parameters by the host computer.

[0017] Preferably, the handshake method is adopted for communication between adjacent PLC communication modules.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] A photovoltaic optimizer composite communication system based on Lora and PLC disclosed by the present invention. The detection unit of the power optimizer can collect the electrical parameter data of the photovoltaic modules in real time, and communicate between the host computer and the photovoltaic optimizer through the Lora communication module, and communicate between the photovoltaic optimizers through the PLC communication module. Through the Lora communication module and the PLC communication module, the host computer can grasp the actual operation conditions of each photovoltaic module in the photovoltaic system in real time, and determine the position information of the photovoltaic module through the unique identification ID of the photovoltaic optimizer, and then issue control instructions according to the actual operation conditions to adjust the working mode of the photovoltaic optimizer to ensure the normal operation of the photovoltaic module. The advantages of the Lora communication module are small volume, strong environmental adaptability, long propagation distance, and many lower-level clients accepted by a single host computer, ensuring the reliability of information. The advantage of the PLC communication module is that the timeliness of transmitting data and instruction information with adjacent photovoltaic optimizers in series is good, and the instructions of the host computer can be quickly sent to each photovoltaic optimizer, improving the real-time performance of the system. The composite communication system of the present invention combines the two, without the need to build an additional communication network, effectively reducing the cost and improving the reliability and stability of communication.

[0020] Furthermore, the antennas of the Lora communication module and the PLC communication module are fixed on the inner wall of the outer shell of the photovoltaic optimizer without contact to prevent electromagnetic interference between the antennas.

[0021] Furthermore, the outer shell of the photovoltaic optimizer is a non-metallic outer shell, further reducing the influence of electromagnetic interference on the communication effect.

[0022] The working method of the above-mentioned photovoltaic optimizer composite communication system based on Lora and PLC disclosed by the present invention has a high degree of automation. When the photovoltaic system is working properly, the upper computer can grasp the working conditions of each photovoltaic module in real time and adjust the working mode of the photovoltaic optimizer according to the actual situation to ensure the normal operation of the photovoltaic modules. The communication mode that combines the Lora communication module and the PLC communication module gives full play to the advantages of both; the upper computer simultaneously receives the electrical parameter data of this machine uploaded by a single photovoltaic optimizer and the electrical parameter data of this photovoltaic optimizer uploaded by adjacent photovoltaic optimizers, records them after comparison, avoids data distortion caused by temporary failures of individual devices or other reasons, improves the reliability and stability of communication, and provides strong support for the intelligent operation and maintenance of photovoltaics.

[0023] Further, after sorting according to the importance requirements of different electrical parameters by the upper computer and uploading them in sequence, it can ensure that data with high importance has a high priority, further improving the reliability of communication.

[0024] Further, the adjacent PLC communication modules communicate with each other using the handshake method to avoid the situation of losing data packets due to the gradual attenuation of the long string of power line carrier communication signal strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the photovoltaic optimizer composite communication system based on Lora and PLC of the present invention;

[0026] Figure 2 is a functional structure diagram of the photovoltaic optimizer of the present invention;

[0027] Figure 3 is a schematic diagram of the communication working principle of the power line carrier PLC communication module of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following further describes the present invention in detail with reference to the drawings and specific embodiments. The content is an explanation of the present invention rather than a limitation:

[0029] As Figure 2 , the photovoltaic optimizer composite communication system based on Lora and PLC of the present invention includes a photovoltaic optimizer connected to each photovoltaic module in the photovoltaic system. The input end of the photovoltaic optimizer is connected to the corresponding photovoltaic module, and the output end is connected in series with other photovoltaic optimizers;

[0030] The photovoltaic optimizer includes a processing unit and a power conversion unit. The power conversion unit is respectively connected to the processing unit and the photovoltaic module. The power conversion unit includes a boost synchronous rectification circuit for performing power conversion on the output of the photovoltaic module. Both the input end and the output end of the power conversion unit are connected with detection units. The detection unit includes two shunt monitors for detecting the current at the input end and the output end of the power conversion unit and two voltage dividers for detecting the voltage at the input end and the output end of the power conversion unit. The processing unit is also connected with a Lora communication module and a PLC communication module.

[0031] The photovoltaic optimizer is connected to the upper computer through the Lora communication module. The upper computer includes a Lora data acquisition module, a data processing module and a storage module. The Lora data acquisition module is communicatively interconnected with the Lora communication module. The Lora data acquisition module is connected to the data processing module, and the data processing module is connected to the storage module. The photovoltaic optimizer is connected to the PLC communication modules of other photovoltaic optimizers through the PLC communication module. Each photovoltaic optimizer has a unique identification ID.

[0032] The antennas of the Lora communication module and the PLC communication module are fixed on the outer wall of the photovoltaic optimizer housing without contact. The photovoltaic optimizer housing is a non-metallic housing.

[0033] The processing unit can adopt an MCU, and STM32F334C8T6 can be used.

[0034] The Lora communication module can adopt RFM98.

[0035] The PLC communication module can adopt MC13250023.

[0036] When the Lora and PLC-based photovoltaic optimizer composite communication system of the present invention is working:

[0037] When the host computer needs to collect data of a certain string of PV optimizers, it confirms the location information of the PV optimizer string according to the unique identifier ID of the PV optimizer. The host computer issues instructions to the Lora communication modules of all PV optimizers in the PV optimizer string. The detection unit collects the electrical parameter data at the input and output ends of the power conversion unit (including data such as input and output voltage and current, PWM duty cycle, etc.), and sends the electrical parameter data to the PLC communication module of the adjacent PV optimizer through the PLC communication module; the processing unit of each PV optimizer in the PV optimizer string sorts the electrical parameter data of this PV optimizer and the electrical parameter data of the adjacent PV optimizer according to the importance requirements of different electrical parameters by the host computer, and then uploads them to the host computer through the Lora communication module in turn; the host computer analyzes and processes all the electrical parameter data uploaded by the PV optimizer string, and compares the electrical parameter data of each PV optimizer at the same moment with the electrical parameter data of this PV optimizer received by the adjacent PV optimizer. If the comparison is consistent, the data is considered reliable and recorded; if the comparison is inconsistent, the data is considered unreliable and not recorded.

[0038] When the host computer sends an instruction, the host computer sends the instruction to the Lora communication module of a certain PV optimizer. After receiving the instruction, this PV optimizer sends the instruction to the Lora communication module of the adjacent PV optimizer through the PLC communication module. The adjacent PLC communication modules communicate with each other using the handshake method until all PV optimizers receive the instruction sent by the host computer, and all PV optimizers change their operating modes according to the instruction sent by the host computer.

[0039] The following further explains the PV optimizer composite communication system based on Lora and PLC and its working method of the present invention with specific embodiments:

[0040] Such as Figure 1 , a PV system includes s PV optimizers and a host computer. m PV optimizers are connected in series at the output to form a PV optimizer string, and n strings of PV optimizer strings are connected in parallel, with a total of s PV optimizers. The i-th PV optimizer is in the j-th string of PV optimizer strings and is connected in series with the adjacent (i - 1)-th and (i + 1)-th PV optimizers.

[0041] Such as Figure 3, the power line carrier PLC module is divided into a transmitting part and a receiving part. The processing unit sends information through the serial port. The logic processing unit combines the signal with the fundamental frequency signal generated by the carrier generator, amplifies the power, and generates a high-frequency signal on the power line through the carrier transformer and transmits it to the adjacent photovoltaic optimizer. The receiving part amplifies the high-frequency signal transmitted from the adjacent photovoltaic optimizer through the power line, detects and shapes the wave, extracts the information, and transmits it to the serial port of the processing unit. The choke filter filters out the high-frequency signal to ensure that the power line carrier PLC module of the i-th photovoltaic optimizer can only receive the adjacent two photovoltaic optimizers connected in series between the positive and negative poles at its output end, namely the (i - 1)-th photovoltaic optimizer and the (i + 1)-th photovoltaic optimizer.

[0042] The initialization steps of the composite communication system are as follows:

[0043] Initialization step 1, the i-th photovoltaic optimizer transmits its ID to the power line carrier PLC modules of the adjacent (i - 1)-th photovoltaic optimizer and the (i + 1)-th photovoltaic optimizer through its power line carrier PLC module;

[0044] Initialization step 2, the i-th photovoltaic optimizer receives the ID numbers of the adjacent (i - 1)-th photovoltaic optimizer and the (i + 1)-th photovoltaic optimizer through the power line carrier PLC module;

[0045] Initialization step 3, the i-th photovoltaic optimizer sends an access request to the host computer through the wireless communication Lora module. The host computer agrees to the access, registers, establishes a connection, and the i-th photovoltaic optimizer receives the data from the host computer;

[0046] Initialization step 4, the host computer starts to request data collection from all the accessed photovoltaic optimizers. The i-th photovoltaic optimizer uploads its own ID number and the ID numbers of the (i - 1)-th and (i + 1)-th photovoltaic optimizers to the host computer;

[0047] Initialization step 5, the data processing module of the host computer starts to pair the received IDs of the photovoltaic optimizers. The data of the i-th photovoltaic optimizer contains the IDs of the (i - 1)-th photovoltaic optimizer at the front end and the (i + 1)-th photovoltaic optimizer at the back end. The back end pairs with the front end, and the front end pairs with the back end to form n chains, each with m IDs, so as to determine the position of the photovoltaic optimizer in the array;

[0048] Initialization step 6, the host computer sends the position information of the i-th photovoltaic optimizer in the j-th string of photovoltaic optimizers to the i-th photovoltaic optimizer for storage.

[0049] The normal working steps of the said composite communication method are as follows:

[0050] In normal operation step 1, when the host computer needs to collect data of the j-th string of PV optimizers, the host computer sends beacons to all PV optimizers in the j-th string of PV optimizers, requesting to accelerate communication for data collection. The processing unit of the i-th PV optimizer in the j-th string starts to obtain data of this PV optimizer from the power conversion unit;

[0051] In normal operation step 2, after the i-th PV optimizer receives the beacon, the processing unit transmits the data already collected from the power unit to the power line carrier PLC modules of the adjacent (i - 1)-th and (i + 1)-th PV optimizers through its power line carrier PLC module;

[0052] In normal operation step 3, the processing unit of the i-th PV optimizer receives data of the adjacent (i - 1)-th and (i + 1)-th PV optimizers through the power line carrier PLC module. The processing unit uploads the data of the three PV optimizers including its own data to the host computer through the wireless communication Lora module;

[0053] In normal operation step 4, the data processing module of the host computer analyzes and processes data of all PV optimizers in the j-th string of PV modules. It compares the data collected by the i-th PV optimizer with the data of the i-th PV optimizer obtained by communication between the (i - 1)-th and (i + 1)-th PV optimizers from the power line carrier PLC module. If the comparison is consistent within a determined time, the data is considered reliable and recorded; if the comparison is inconsistent, the data is considered unreliable and not recorded;

[0054] In normal operation step 5, when the host computer sends an instruction, the Lora information collection module of the host computer sends the instruction information to the i-th PV optimizer in the j-th string. The PV optimizer receiving the instruction transmits the instruction information to the (i - 1)-th and (i + 1)-th PV optimizers through the power line carrier PLC module. The (i - 1)-th PV optimizer will transmit the instruction information to the (i - 2)-th PV optimizer, and the (i + 1)-th PV optimizer will transmit the instruction information to the (i + 2)-th PV optimizer, and so on. The instruction information will be transmitted to all PV optimizers in this string of PV optimizers, and all optimizers will change their operation modes according to the instruction information.

[0055] It should be noted that the above is only one of the embodiments of the present invention. Equivalent changes made to the system described according to the present invention are all included in the protection scope of the present invention. Those skilled in the art of the present invention can make similar substitutions in the described specific examples, as long as they do not deviate from the structure of the present invention or exceed the scope defined by this claim book, they all belong to the protection scope of the present invention.

Claims

1. A working method of a photovoltaic optimizer composite communication system based on Lora and PLC, characterized in that The photovoltaic optimizer composite communication system based on LoRa and PLC includes photovoltaic optimizers connected to each photovoltaic module in the photovoltaic system. The input end of the photovoltaic optimizer is connected to the corresponding photovoltaic module, and the output end is connected in series with other photovoltaic optimizers. The photovoltaic optimizer includes a processing unit and a power conversion unit. The power conversion unit is respectively connected to the processing unit and the photovoltaic module. Detection units are connected to both the input end and the output end of the power conversion unit. The processing unit is also connected to a LoRa communication module and a PLC communication module. The photovoltaic optimizer is connected to the upper computer through the LoRa communication module and connected to the PLC communication modules of other photovoltaic optimizers through the PLC communication module. Each photovoltaic optimizer has a unique identification ID. It includes the following steps: When the upper computer needs to collect data of a string of photovoltaic optimizers, it confirms the position information of the string of photovoltaic optimizers according to the unique identification ID of the photovoltaic optimizer. The upper computer issues an instruction to the LoRa communication modules of all the photovoltaic optimizers in the string of photovoltaic optimizers. The detection unit collects the electrical parameter data at the input end and the output end of the power conversion unit, and sends the electrical parameter data to the PLC communication module of the adjacent photovoltaic optimizer through the PLC communication module. The processing unit of each photovoltaic optimizer in the string of photovoltaic optimizers sorts the electrical parameter data of this photovoltaic optimizer and the electrical parameter data of the adjacent photovoltaic optimizer, and uploads them to the upper computer through the LoRa communication module in turn. The upper computer analyzes and processes all the electrical parameter data uploaded by the string of photovoltaic optimizers, and compares the electrical parameter data of each photovoltaic optimizer at the same moment with the electrical parameter data of this photovoltaic optimizer received by the adjacent photovoltaic optimizer. If the comparison is consistent, the data is considered reliable and recorded; if the comparison is inconsistent, the data is considered unreliable and not recorded. When the upper computer sends an instruction, the upper computer sends the instruction to the LoRa communication module of a certain photovoltaic optimizer. After receiving the instruction, this photovoltaic optimizer sends the instruction to the LoRa communication module of the adjacent photovoltaic optimizer through the PLC communication module until all the photovoltaic optimizers receive the instruction sent by the upper computer, and all the photovoltaic optimizers change the operation mode according to the instruction sent by the upper computer.

2. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 1, characterized in that, The power conversion unit includes a boost synchronous rectification circuit.

3. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 1, characterized in that, The detection unit includes two shunt monitors for detecting the current at the input end and the output end of the power conversion unit and two voltage dividers for detecting the voltage at the input end and the output end of the power conversion unit.

4. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 1, characterized in that, The upper computer includes a LoRa data acquisition module, a data processing module and a storage module; the LoRa data acquisition module is communicatively interconnected with the LoRa communication module, the LoRa data acquisition module is connected to the data processing module, and the data processing module is connected to the storage module.

5. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 1, characterized in that, The antennas of the LoRa communication module and the PLC communication module are fixed on the outer wall of the photovoltaic optimizer housing without contact.

6. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 5, characterized in that, The photovoltaic optimizer housing is a non-metallic housing.

7. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 1, characterized in that, The sorting of the electrical parameter data is sorted according to the importance requirements of different electrical parameters by the upper computer.

8. The working method of the photovoltaic optimizer composite communication system based on Lora and PLC according to claim 1, characterized in that, The adjacent PLC communication modules communicate with each other by the handshake method.

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