A power line communication method, apparatus and system

Abstract

This invention relates to the field of power line communication and provides a power line communication method, apparatus, and system. The method includes: when a data acquisition unit receives an inverter control signal, it identifies the inverter control signal to obtain an identification control signal and sends the identification control signal to a central coordinator; after receiving the identification control signal, the central coordinator transmits the identification control signal to the target site using a QPSK modulation transmission mechanism based on inter-network coordination frames; the target site demodulates the identification control signal and sends it to the target inverter. According to one embodiment of this invention, the delay time for downlink data processing in PLC communication is reduced, the communication efficiency of the PLC is improved, and a fast inverter response is achieved.

Description

Technical Field

[0001] This invention relates to the field of power line communication, and more particularly to a power line communication method, apparatus, and system. Background Technology

[0002] Power line communication (PLC) is a communication technology that uses power lines as a communication medium to transmit signals via carrier waves. In one scenario in photovoltaic power generation, a PLC communication system includes a data acquisition unit (SAU), a central coordinator (CCO), stations (STA), and inverters. The SAU can send control signals to the inverters via the power lines to schedule the inverters, while the inverters send equipment operation information to the SAU via the power lines.

[0003] In recent years, with the emergence of concepts such as "smart grid" and "panoramic monitoring," the State Grid Corporation of China has increasingly stringent requirements for power plant backend dispatch data, even imposing specific time requirements on PLC communication efficiency. To meet these time requirements, the photovoltaic industry demands rapid control of inverters from the backend. Current technologies primarily employ optimization of the CCO and STA software to reduce the processing delay of downlink data in PLC communication. However, the effectiveness of existing technologies in improving PLC communication efficiency and achieving rapid inverter response is limited. Summary of the Invention

[0004] This invention provides a power line communication method to solve the problems of low PLC communication efficiency, long delay time in processing downlink data, and inability to achieve fast inverter response.

[0005] The present invention is implemented as follows: a power line communication method is provided, comprising:

[0006] When the data acquisition unit receives the inverter control signal, it identifies the inverter control signal to obtain an identification control signal, and sends the identification control signal to the central coordinator.

[0007] After receiving the identification control signal, the central coordinator transmits the identification control signal to the target site using QPSK modulation and transmission mechanism based on the inter-network coordination frame.

[0008] The target site demodulates the identification control signal and then sends it to the target inverter.

[0009] Furthermore, before the central coordinator transmits the identification control signal to the target site, the method further includes the following steps:

[0010] The central coordinator compresses the identification control signal;

[0011] The target site demodulates the identification control signal and sends it to the target inverter. The specific steps of the method are as follows:

[0012] The target station demodulates the identification control signal;

[0013] The target site decompresses the demodulated identification control signal and sends the decompressed signal to the target inverter.

[0014] Furthermore, the step of the central coordinator compressing the identification control signal specifically includes:

[0015] Key information is extracted from the identification control signal based on the communication protocol message format.

[0016] The extracted key information is synthesized into message indication information, wherein the message indication information is information required during data communication.

[0017] A compressed message is generated based on the message instruction information.

[0018] Furthermore, the step of generating the compressed message based on the message indication information specifically includes:

[0019] The compressed message consists of message indication information, Modbus start address, and Modbus register data.

[0020] Furthermore, after the central coordinator receives the identification control signal, the method further includes the following steps:

[0021] Determine whether the received signal contains the identifier. If so, transmit the identifier control signal to the target station using QPSK modulation and transmission mechanism based on the inter-network coordination frame.

[0022] If not, the received signal is modulated based on a payload MPDU frame format and then transmitted to the target station.

[0023] Furthermore, the identifier includes setting a frame header identifier in the inverter control signal, wherein the frame header identifier is used to characterize the message type of the signal.

[0024] This invention also provides a power line communication device, comprising:

[0025] The first processing unit is used to identify the inverter control signal to obtain an identification control signal when the data acquisition unit receives the inverter control signal, and then send the identification control signal to the central coordinator.

[0026] The second processing unit is used to transmit the identification control signal to the target site after the central coordinator receives the identification control signal, based on the QPSK modulation transmission mechanism for the inter-network coordination frame.

[0027] The third processing unit demodulates the identification control signal and sends it to the target inverter.

[0028] After the inverter control signals are identified, the central coordinator can recognize them and use a QPSK modulation / demodulation mechanism based on inter-network coordination frames to quickly send the inverter control signals to the inverter. This reduces the latency of PLC communication for downlink data processing, improves PLC communication efficiency, and enables the inverter to respond quickly.

[0029] Meanwhile, since the data capacity of inter-network coordination frames is limited, the identification control signals are compressed based on the communication protocol message format before data transmission, thereby increasing the data capacity and further improving the communication efficiency of the PLC. Attached Figure Description

[0030] Figure 1 This is a flowchart of an embodiment of the power line communication method provided by the present invention;

[0031] Figure 2 This is a flowchart of another embodiment of the power line communication method provided by the present invention;

[0032] Figure 3 This is a flowchart of a specific implementation of the compression step provided by the present invention;

[0033] Figure 4-a This is a schematic diagram based on Modbus message frames in one embodiment of the present invention;

[0034] Figure 4-b This is a schematic diagram of message indication information in one embodiment of the present invention;

[0035] Figure 4-c This is a schematic diagram of a compressed message frame in one embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the structure of the power line communication device provided by the present invention;

[0037] Figure 6This is a schematic diagram of the power line communication system provided by the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] To facilitate understanding of the technical terms used in this field, the following explanations are provided.

[0040] PLC: Power Line Communication.

[0041] SAU: Data Acquisition Unit.

[0042] CCO: Central Coordinator.

[0043] MPDU: MAC Protocol Data Unit.

[0044] Existing technologies mainly use software optimization for CCO and STA to reduce the processing delay of downlink data in PLC communication. However, they do not identify the inverter control signals. Instead, they do not identify the inverter control signals and use QPSK modulation transmission mechanism based on inter-network coordination frames to achieve fast inverter response and shorten data processing delay.

[0045] Example 1

[0046] refer to Figure 1 As shown, Figure 1 This is a flowchart of an embodiment of the power line communication method provided by the present invention.

[0047] In step S1, when the data acquisition unit receives the inverter control signal, it identifies the inverter control signal to obtain an identification control signal and sends the identification control signal to the central coordinator.

[0048] It is understood that, in the embodiments of the present invention, the SAU is an automated device that can collect and process data in real time on site. It is connected to an external communication device through an external interface. The signal initiated by the external communication device to the SAU is a source control terminal or a northbound device, etc., used to control and allocate the output power of the inverter.

[0049] It is understood that, in the embodiments of the present invention, after the SAU receives the inverter control signal, it performs identification processing on the inverter control signal to obtain an identification control signal so that the CCO can identify the received signal as an inverter control signal. The SAU and the CCO are connected through a communication line. The SAU sends the identification control signal to the CCO, and then the CCO performs the corresponding operation.

[0050] In step S3, after receiving the identification control signal, the central coordinator transmits the identification control signal to the target site based on the QPSK modulation transmission mechanism using the inter-network coordination frame.

[0051] It is understood that in the embodiments of the present invention, the MPDU (MAC Protocol Data Unit) is a MAC layer protocol data unit provided by the MAC sublayer to the physical layer. It is the basic transmission unit for transmitting data between the physical layers of different stations. The MPDU frame format mainly includes two parts: frame control and frame payload. The frame control is 16 bytes. The inter-network coordination frame is a MAC layer protocol data unit with only the frame control part; that is, the inter-network coordination frame is an MPDU frame without a frame payload. After the CCO receives the identification control signal, it loads the message data of the identification control signal into the frame control of the MPDU without a frame payload. Since the MPDU has no frame payload, i.e., only 16 bytes of frame control, the transmission rate of the MPDU without a frame payload is greatly improved compared to the transmission rate of the entire MPDU frame.

[0052] It is understood that, in the embodiments of the present invention, the signal is transmitted based on a loadless MPDU, and the signal modulation method used includes digital modulation methods such as BPSK, QPSK, and DPSK, without any specific limitation. In this embodiment, based on a comprehensive comparison of the transmitted data packet size, signal transmission stability, and transmission rate performance, quadrature phase shift keying (QPSK) modulation is selected to transmit the identification control signal to the target station, thereby improving the transmission efficiency of the control signal.

[0053] In step S5, the target site demodulates the identification control signal and then sends it to the target inverter.

[0054] It is understood that, in the embodiments of the present invention, the CCO modulates the identification control signal using QPSK digital signal and sends it to the target site. After receiving the modulated signal, the target site performs corresponding QPSK digital demodulation, including digital-to-analog conversion, decimation or interpolation, matched filtering, clock and carrier recovery, etc., and sends the demodulated identification control signal to the target inverter to achieve adjustment and control of the inverter power.

[0055] According to one embodiment of the present invention, the delay time of PLC communication for downlink data processing is effectively reduced, the communication efficiency of PLC is improved, and the inverter can achieve fast response.

[0056] Example 2

[0057] refer to Figure 2 As shown, Figure 2 A flowchart of another embodiment of the power line communication method provided by the present invention.

[0058] In this embodiment of the application, the main difference from Embodiment 1 is that, before the central coordinator transmits the identification control signal to the target site, the following steps are also included:

[0059] In step S2, the central coordinator compresses the identification control signal;

[0060] It is understood that, in the embodiments of the present invention, after receiving the identification control signal, the CCO compresses the identification control signal using a compression algorithm before modulating the signal.

[0061] In step S5, the specific process of the target site demodulating the identification control signal and sending it to the target inverter also includes the following steps:

[0062] In step S51, the target station demodulates the identification control signal;

[0063] It is understood that, in the embodiments of the present invention, the CCO loads the compressed message data into the frame control of the MPDU without frame payload, and after QPSK digital signal modulation, it is sent to the target station. After receiving the modulated signal, the target station performs the corresponding QPSK digital demodulation, which specifically includes digital-to-analog conversion, decimation or interpolation, matched filtering, clock and carrier recovery, etc.

[0064] In step S52, the target site decompresses the demodulated identification control signal and sends the decompressed signal to the target inverter.

[0065] It is understood that, in the embodiments of the present invention, the target site uses a corresponding compression algorithm to decompress the demodulated identification control signal obtained after QPSK demodulation, and sends the decompressed signal to the target inverter.

[0066] By compressing the identification control signal before modulation, the data compression process reduces the amount of data processing, improves the overall communication rate, and further accelerates the inverter's response speed. On the other hand, it provides more single-pass data capacity for the inverter control signal data, allowing the backend to control the inverter with more data and greater flexibility.

[0067] Example 3

[0068] refer to Figure 3 , Figure 4-a , Figure 4-b As shown, Figure 3 A flowchart illustrating a specific implementation of the compression step provided by the present invention. Figure 4-a This is a schematic diagram based on Modbus message frames in one embodiment of the present invention. Figure 4-b This is a schematic diagram of message indication information in one embodiment of the present invention. In this embodiment, the step of the central coordinator compressing the identification control signal specifically includes:

[0069] In step S21, key information of the identification control signal is extracted based on the communication protocol message format;

[0070] It is understood that, in the embodiments of the present invention, based on the communication protocol message format, taking the Modbus message format as an example, such as... Figure 4-a As shown, the message includes information such as frame header identifier, Modbus address, function code, register start address, number of registers, number of bytes, register data, and checksum. In order to achieve data compression, the information required in the communication process is extracted from the message, and the space occupied by the specific data is omitted by recording the start address of the unnecessary information.

[0071] It is understood that in the embodiments of the present invention, key information mainly includes, for example, the Modbus address. In data communication, we only need to use 0-63, so the Modbus address only needs to occupy 6 bits. It also includes, for example, the function code and the number of registers. The function code has two types: 0x06 and 0x10. 0 represents the 0x06 function code, with 1 register and 2 bytes; 1 represents the 0x10 function code, with 1 register and 2 bytes; 2 represents the 0x10 function code, with 2 registers and 4 bytes; and 3 represents the 0x10 function code, with 3 registers and 6 bytes. This representation only requires 2 bits for both the function code and the number of registers.

[0072] In step S22, the extracted key information is synthesized into message indication information, wherein the message indication information is the information required in the data communication process;

[0073] It is understood that, in embodiments of the present invention, the Modbus address, function code, and number of registers in step S21 are combined into message indication information to provide the information required during data communication, such as... Figure 4-b As shown, the message indication information only requires 8 bits of data storage, which is one byte.

[0074] In step S23, a compressed message is generated based on the message instruction information.

[0075] It is understood that, in the embodiments of the present invention, a compressed message is generated according to the message indication information, and the compressed message contains at least the message indication information for the purpose of data communication.

[0076] In other possible embodiments, in addition to message indication information, the compressed message may also retain checksum information, which is not specifically limited.

[0077] Data compression is achieved by extracting the necessary information during data communication as separate message indication information and removing other unnecessary information, thereby increasing the data carrying capacity per message by saving space.

[0078] Example 4

[0079] refer to Figure 4-c As shown, Figure 4-c This is a schematic diagram of a compressed message frame in one embodiment of the present invention. In this embodiment, the step of generating a compressed message based on message indication information is as follows:

[0080] The compressed message consists of the message indication information, the Modbus start address, and the Modbus register data.

[0081] It is understood that, in the embodiments of the present invention, as Figure 4-c As shown, the generated compressed message retains only the message indication information required for communication and the Modbus start address before compression of the original message. The remaining space is used to store Modbus register data. Therefore, the generated compressed message consists of message indication information, Modbus start address, and Modbus register data.

[0082] It is understood that, in the embodiments of the present invention, the Modbus starting address is information that needs to be provided during the data decompression and recovery process.

[0083] Example 5

[0084] In this embodiment, after the central coordinator receives the identification control signal, it further includes the following steps:

[0085] Determine whether the received signal contains an identifier. If so, transmit the identifier control signal to the target station using QPSK modulation transmission mechanism based on the inter-network coordination frame.

[0086] It is understood that, in the embodiments of the present invention, the SAU obtains the status information of the device by continuously sending device status query signals to the inverter. Since the SAU sends both the status query signals it sends and the control signals it receives to the CCO via the communication line, and the CCO cannot distinguish between the two different signals, the SAU identifies the control signals before sending them to the CCO. After receiving the signals, the CCO makes a judgment based on the identification.

[0087] It is understood that, in the embodiments of the present invention, the determination process specifically involves checking whether the received signal message contains an identifier. If it contains an identifier, the received signal is a control signal. The signal is then transmitted based on the inter-network coordination frame, that is, the message data of the control signal is loaded into the payload-free MPDU frame. The signal modulation method can be digital modulation methods such as BPSK, QPSK, DPSK, etc., and is not specifically limited.

[0088] In this embodiment, based on a comprehensive comparison of the data packet size, signal transmission stability, and transmission rate performance, quadrature phase shift keying (QPSK) modulation is selected to transmit the identification control signal to the target station, thereby improving the transmission efficiency of the control signal.

[0089] If not, the received signal will be modulated based on the inter-network coordination frame and then transmitted to the target station.

[0090] It is understood that, in the embodiments of the present invention, if the received signal message does not contain an identifier, then the received signal is a status query signal. The signal is then transmitted based on a payload MPDU frame, that is, the message data of the status query signal is loaded into the frame payload of the MPDU. The signal modulation method can be digital modulation methods such as BPSK, QPSK, DPSK, etc., and there is no specific limitation. The status query signal is transmitted to the target station after modulation.

[0091] By marking and distinguishing status query signals and inverter control signals, and using different communication processing mechanisms for different signals, especially for inverter control signals, a QPSK modulation transmission mechanism based on no-load MPDU frame format is used to achieve fast communication of inverter control signals and fast response of the inverter, thereby reducing the delay time of PLC communication for inverter control signal processing and improving PLC communication efficiency.

[0092] Example 6

[0093] In this embodiment, the identifier includes setting a frame header identifier in the inverter control signal, wherein the frame header identifier is used to characterize the message type of the signal.

[0094] It is understood that, in the embodiments of the present invention, setting a frame header identifier in the inverter control signal specifically means setting a 2-byte space in the message frame header, using hexadecimal identifiers, such as 0xAC, 0xBD, etc., to identify and distinguish the message type of the signal.

[0095] In some other embodiments, the message type of the signal can also be characterized by setting an identifier range or an identifier special character, without any specific limitation.

[0096] By setting an identifier, the CCO can easily identify the message type as an inverter control signal, thereby enabling the use of a separate QPSK modulation transmission mechanism based on the no-load MPDU frame format. This allows for fast communication of inverter control signals and rapid response from the inverter, reducing the delay time of PLC communication in processing inverter control signals and improving PLC communication efficiency.

[0097] Example 7

[0098] refer to Figure 5 As shown, Figure 5 This is a schematic diagram of the structure of the power line communication device provided by the present invention, as a reference. Figure 1 The implementation of the power line communication method shown in this embodiment provides a power line communication device, which is similar to... Figure 1 Corresponding to the method embodiment shown, the apparatus includes:

[0099] The first processing unit 21 is used to identify the inverter control signal to obtain an identification control signal when the data acquisition unit receives the inverter control signal, and then send the identification control signal to the central coordinator.

[0100] The second processing unit 22 is used to transmit the identification control signal to the target station based on the QPSK modulation transmission mechanism using the no-load MPDU frame format after the central coordinator receives the identification control signal.

[0101] The third processing unit 23 is used to demodulate the identification control signal at the target site and then send it to the target inverter.

[0102] The beneficial effect of the power line communication device 20 in this embodiment of the invention is that after the inverter control signal is identified, the central coordinator can identify the inverter control signal and use a QPSK modulation / demodulation mechanism based on the no-load MPDU frame format to quickly send the inverter control signal to the inverter. Therefore, it can reduce the delay time of PLC communication for downlink data processing, improve the communication efficiency of PLC, and realize the inverter's fast response.

[0103] Example 8

[0104] refer to Figure 6 As shown, Figure 6 This is a schematic diagram of the power line communication system provided by the present invention. This embodiment provides a power line communication system, including:

[0105] One or more processors 11; and

[0106] The memory 12 is used to store one or more programs, wherein when the one or more programs are executed by one or more processors 11, the one or more processors 11 cause the one or more processors 11 to implement the steps of the power line communication method of any of the above embodiments.

[0107] The beneficial effect of the power line communication system 10 in this embodiment of the invention is that after the inverter control signal is identified, the central coordinator can identify the inverter control signal and use a QPSK modulation / demodulation mechanism based on the no-load MPDU frame format to quickly send the inverter control signal to the inverter. Therefore, it can reduce the delay time of PLC communication for downlink data processing, improve the communication efficiency of PLC, and realize the inverter's fast response.

[0108] Example 9

[0109] This invention also provides a computer-readable storage medium storing program instructions, which, when executed by a processor, implement the steps of the power line communication method of any of the above embodiments.

[0110] The beneficial effect of the storage medium of the present invention is that after the inverter control signal is identified, the central coordinator can identify the inverter control signal and use a QPSK modulation / demodulation mechanism based on the no-load MPDU frame format to quickly send the inverter control signal to the inverter. Therefore, it can reduce the delay time of PLC communication for downlink data processing, improve the communication efficiency of PLC, and realize the inverter's fast response.

[0111] This invention can be used in a wide range of general-purpose or special-purpose computer system environments or configurations.

[0112] Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and distributed computing environments that include any of the above systems or devices.

[0113] In summary, after the inverter control signal provided in this embodiment of the invention is identified, the central coordinator can recognize the inverter control signal and use a QPSK modulation / demodulation mechanism based on the no-load MPDU frame format to transmit the identified control signal to the target site. After demodulation, the identified control signal is sent to the target inverter, which can reduce the latency of PLC communication for downlink data processing and achieve fast inverter response. In addition, compression processing increases the carrying capacity of single data transmission, thereby solving the problems of low PLC communication efficiency and inability to achieve fast inverter response, and bringing about the effect of improving PLC communication efficiency.

[0114] It is understood that those skilled in the art can combine various implementation methods in the above embodiments under the guidance of the above examples to obtain technical solutions with multiple implementation methods.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power line communication method, characterized in that, include: When the data acquisition unit receives the inverter control signal, it identifies the inverter control signal to obtain an identification control signal, and sends the identification control signal to the central coordinator. After receiving the identification control signal, the central coordinator transmits the identification control signal to the target site using QPSK modulation and transmission mechanism based on the inter-network coordination frame. The target site demodulates the identification control signal and then sends it to the target inverter; After the central coordinator receives the identification control signal, the method further includes the following steps: Determine whether the received signal contains the identifier. If so, transmit the identifier control signal to the target station using QPSK modulation and transmission mechanism based on the inter-network coordination frame. If not, the received signal is modulated based on a payload MPDU frame format and then transmitted to the target station.

2. The power line communication method as described in claim 1, characterized in that, Before transmitting the identification control signal to the target station using the QPSK modulation transmission mechanism based on the inter-network coordination frame, the method further includes the following steps: The central coordinator compresses the identification control signal; The target site demodulates the identification control signal and sends it to the target inverter. The specific steps of the method are as follows: The target station demodulates the identification control signal; The target site decompresses the demodulated identification control signal and sends the decompressed signal to the target inverter.

3. The power line communication method as described in claim 2, characterized in that, The step of the central coordinator compressing the identification control signal specifically includes: Key information is extracted from the identification control signal based on the communication protocol message format; The extracted key information is synthesized into message indication information, wherein the message indication information is information required during data communication. A compressed message is generated based on the message instruction information.

4. The power line communication method as described in claim 3, characterized in that, The step of generating the compressed message based on the message indication information specifically includes: The compressed message consists of message indication information, Modbus start address, and Modbus register data.

5. The power line communication method as described in claim 1, characterized in that, The identifier includes setting a frame header identifier in the inverter control signal, wherein the frame header identifier is used to characterize the message type of the signal.

6. A power line communication device, characterized in that, include: The first processing unit is used to identify the inverter control signal to obtain an identification control signal when the data acquisition unit receives the inverter control signal, and then send the identification control signal to the central coordinator. The second processing unit is used to transmit the identification control signal to the target site based on the QPSK modulation transmission mechanism after the central coordinator receives the identification control signal and the inter-network coordination frame. The third processing unit is used to demodulate the identification control signal at the target site and then send it to the target inverter. The second processing unit is further configured to: Determine whether the received signal contains the identifier. If so, transmit the identifier control signal to the target station using QPSK modulation and transmission mechanism based on the inter-network coordination frame. If not, the received signal is modulated based on a payload MPDU frame format and then transmitted to the target station.

7. A power line communication system, characterized in that, include: One or more processors; as well as A memory for storing one or more programs, wherein, when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the power line communication method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores program instructions that, when executed by a processor, implement the steps of the power line communication method according to any one of claims 1 to 5.

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