A method for ac photovoltaic carrier communication power adaptation

Abstract

The application provides an AC photovoltaic carrier communication power adaptive method, relates to the technical field of power line carrier communication, and comprises the following steps: acquiring communication quality parameters, power line channel state parameters and external subarray carrier message statistical parameters of each STA communication link, determining link attenuation state, cross-subarray crosstalk state, a main crosstalk source subarray and a communication quality margin of each STA communication link; generating a basic power demand, a crosstalk suppression correction and a link compensation, informing the main crosstalk source subarray to reduce transmission power when the crosstalk exceeds the standard, only increasing the power of the corresponding link when the quality of a single STA link is insufficient, and determining a target transmission power. The AC photovoltaic carrier communication power adaptive method can take into account cross-subarray crosstalk suppression and weak link compensation, reduce invalid power improvement and adjustment oscillation, and improve the stability and adjustment accuracy of multi-subarray carrier communication.

Description

Technical Field

[0001] This invention relates to the field of power line carrier communication technology, specifically to a power adaptive method for AC photovoltaic carrier communication. Background Technology

[0002] With the application of distributed photovoltaic (PV), residential PV, and industrial / commercial PV systems, data exchange is required between PV inverters, grid-connected boxes, metering terminals, monitoring terminals, and local communication nodes. Since AC PV systems typically already have AC power lines installed, power line carrier communication, using AC power lines as the communication transmission medium, can achieve information transmission between different nodes without laying additional communication cables. Existing AC PV carrier communication methods usually couple carrier communication signals to the AC power lines through a carrier communication module, and the receiving end extracts the carrier communication signals from the AC power lines to complete the communication transmission.

[0003] However, AC power lines in AC photovoltaic systems are not dedicated communication channels. Line impedance, load variations, branch structures, background noise, and inverter operating noise can all cause attenuation and interference levels in the carrier communication link. Existing carrier communication equipment often uses fixed transmission power or simple power grading to send carrier communication signals, making it difficult to dynamically match the appropriate transmission power according to channel conditions and communication quality. This can easily lead to problems such as insufficient transmission power causing communication instability, or excessive transmission power causing power redundancy and communication interference. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a power adaptive method for AC photovoltaic carrier communication. By identifying crosstalk across subarrays and adjusting power differently on a single STA link, it solves the problems of severe crosstalk, unstable weak link communication, and insufficient targeted power adjustment in multi-subarray AC photovoltaic carrier communication.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a power adaptive method for AC photovoltaic carrier communication, applied to an AC photovoltaic system comprising multiple subarrays, each subarray having a master node (CCO), several slave nodes (STAs), and an inverter, wherein the CCO and the STAs are networked in a star topology, and the method includes:

[0006] S1. Establish a carrier communication link on the AC side power line of the AC photovoltaic system, control the carrier communication module to send a carrier communication signal to the AC side power line at the current transmission power, and obtain the communication quality parameters corresponding to each STA communication link, the power line channel status parameters corresponding to the carrier communication link, and the carrier message statistics parameters from the external subarray respectively.

[0007] S2. Determine the link attenuation state corresponding to AC side power line transmission attenuation based on the power line channel state parameters, determine the cross-subarray crosstalk state and main crosstalk source subarrays based on the external subarray carrier message statistics parameters, and determine the communication quality margin of each STA communication link based on the difference between the communication quality parameters corresponding to each STA communication link and the preset reliable communication conditions.

[0008] S3. Generate a basic power requirement based on the link attenuation state, generate a crosstalk suppression correction based on the cross-subarray crosstalk state, and generate a corresponding link compensation based on the communication quality margin.

[0009] S4. Based on the basic power requirement, and according to the cross-subarray crosstalk state and the communication quality margin, selectively use the crosstalk suppression correction amount and the link compensation amount to correct the basic power requirement, thereby generating the carrier communication transmit power requirement; wherein, when the cross-subarray crosstalk state reaches a preset crosstalk condition, the CCO of this subarray sends a crosstalk notification carrying the subarray number to the main crosstalk source subarray, and after completing the subarray number matching, the CCO of the main crosstalk source subarray lowers the current transmit power by using the crosstalk suppression correction amount as the adjustment range; when the communication quality margin of a single STA communication link is lower than a preset reliability margin, the current transmit power corresponding to the STA communication link is increased by using the link compensation amount as the adjustment range, while the transmit power corresponding to other STA communication links remains unchanged;

[0010] S5. Based on the carrier communication transmission power requirement, determine the target transmission power of the subarray CCO and / or the target transmission power corresponding to a single STA communication link, and control the corresponding carrier communication module to transmit carrier communication signals on the AC side power line according to the target transmission power.

[0011] Preferably, the communication quality parameters include at least two of the following: received signal strength, signal-to-noise ratio, bit error rate, packet loss rate, retransmission count, and acknowledgment success rate; the power line channel status parameters include at least one of the following: channel attenuation, line impedance change, and carrier received level change; the carrier message statistics parameters of the external subarrays include the subarray number carried by the carrier message, the total number of external subarray carrier messages received within a preset statistical period, and the number of carrier messages corresponding to each external subarray.

[0012] Preferably, determining the link attenuation state includes: controlling the carrier communication module to send a reference carrier signal to the AC power line at the current transmit power, obtaining the reference carrier reception level fed back by the receiver of the carrier communication link, determining the channel attenuation amount according to the attenuation relationship between the current transmit power and the reference carrier reception level, and determining the link attenuation state according to the preset attenuation interval to which the channel attenuation amount belongs.

[0013] Preferably, determining the initial value of the current transmit power includes: the local subarray CCO sending a silence notification to the adjacent subarray CCO, causing the adjacent subarray CCO to stop transmitting carrier communication signals within a preset silence duration; setting the transmit gain of the local subarray CCO to a preset minimum gain level, and performing PING communication tests on each STA in the local subarray; when there is an STA that does not meet the preset communication success conditions, gradually increasing the transmit gain until all STAs meet the preset communication success conditions; and determining the transmit power corresponding to the current transmit gain as the initial value of the current transmit power.

[0014] Preferably, the determination of the communication quality margin includes: comparing the communication quality parameters corresponding to each STA communication link with the corresponding communication quality thresholds in the preset reliable communication conditions to obtain the quality difference value corresponding to each communication quality parameter; converting each quality difference value into a normalized quality difference value that is consistent with the direction of communication quality improvement; and determining the communication quality margin of the corresponding STA communication link based on each normalized quality difference value.

[0015] Preferably, the generation of the basic power demand includes: dividing the link attenuation state into at least two attenuation levels and configuring a corresponding basic power demand range for each attenuation level; and determining the basic power demand from the corresponding basic power demand range according to the attenuation level to which the link attenuation state belongs.

[0016] Preferably, the determination of the cross-subarray crosstalk state and the main crosstalk source subarray includes: according to the carrier packet statistical parameters from the external subarray, counting the total number of external subarray carrier packets received within a preset statistical period, and using the total number of external subarray carrier packets as the crosstalk value; according to the subarray number carried by each external subarray carrier packet, counting the number of carrier packets corresponding to each external subarray; when the crosstalk value exceeds a preset crosstalk threshold, determining that the cross-subarray crosstalk state has reached the preset crosstalk condition, and determining the external subarray with the largest number of carrier packets as the main crosstalk source subarray.

[0017] Preferably, the crosstalk suppression correction amount is the power difference between two adjacent transmit power levels; after the CCO of the main crosstalk source subarray completes the subarray number matching, the current transmit power is reduced by one transmit power level, and is not lower than the initial value of the current transmit power, and the repeated reduction of transmit power is stopped within the preset anti-repetition adjustment window.

[0018] Preferably, the link compensation amount is the power difference between two adjacent transmit power levels; when the communication quality margin of a single STA communication link is lower than the preset reliability margin, the current transmit power corresponding to the STA communication link is increased by one transmit power level, and does not exceed the preset maximum transmit power, while the transmit power corresponding to other STA communication links remains unchanged; when communication still fails continuously at the preset maximum transmit power, the transmit power corresponding to the STA communication link is restored to the initial value of the current transmit power, and the increase stops within a preset lockout period.

[0019] Preferably, determining the target transmission power includes: presetting multiple transmission power levels arranged from low to high according to transmission power, and establishing a correspondence between transmission gain levels and transmission power levels; limiting the transmission power requirement of the carrier communication, and selecting the corresponding level from the transmission power levels as the target transmission power.

[0020] This invention provides a power adaptive method for AC photovoltaic carrier communication. It has the following beneficial effects:

[0021] This adaptive power method for AC photovoltaic carrier communication simultaneously acquires power line channel state parameters, communication quality parameters of each STA communication link, and external subarray carrier message statistics. It then determines the link attenuation state, cross-subarray crosstalk state, main crosstalk source subarrays, and communication quality margins of each STA communication link. Based on this, it generates the basic power demand, crosstalk suppression correction, and link compensation. This method can distinguish between different communication anomalies caused by power line transmission attenuation, external subarray crosstalk, and individual STA link quality degradation. It avoids uniformly increasing the transmission power of the entire subarray based on a single communication indicator, thereby improving the targeting and accuracy of AC photovoltaic carrier communication power adjustment.

[0022] When cross-subarray crosstalk reaches a preset condition, this invention causes the main crosstalk source subarray to lower its transmit power by sending a crosstalk notification carrying the subarray number. Furthermore, when the quality of a single STA communication link is insufficient, the power is only increased for that STA's communication link. This suppresses inter-subarray carrier crosstalk while ensuring the communication reliability of weak links. Through initial transmit power calibration, graded power adjustment, anti-repetitive adjustment window, maximum power limit, and power recovery and locking processing after continuous communication failures, it also reduces adjustment oscillations and ineffective power increases caused by frequent power increases and decreases, thereby improving the operational stability and fault handling capabilities of multi-subarray AC photovoltaic carrier communication systems. Attached Figure Description

[0023] Figure 1 This is an overall flowchart of the AC photovoltaic carrier communication power adaptive method of the present invention;

[0024] Figure 2 This is a flowchart illustrating the dynamic adjustment of carrier communication transmit power according to the present invention;

[0025] Figure 3 This is a flowchart illustrating the configuration of communication quality and power adjustment parameters for this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] like Figure 1 As shown, this embodiment of the invention provides a power adaptive method for AC photovoltaic carrier communication, applied to an AC photovoltaic system comprising multiple subarrays. Each subarray has a master node (CCO), several slave nodes (STA), and an inverter. The CCO and STA are networked in a star topology. The method includes:

[0029] Each STA is connected to its corresponding photovoltaic inverter. Each subarray is configured with a unique subarray number. The CCO distinguishes between messages from its own subarray and messages from external subarrays by the subarray number.

[0030] S1. Establish a carrier communication link on the AC side power line of the AC photovoltaic system, control the carrier communication module to send carrier communication signals to the AC side power line at the current transmission power, and obtain the communication quality parameters, power line channel status parameters, and carrier message statistics parameters from external subarrays corresponding to each STA communication link.

[0031] The determination of the initial value of the current transmit power includes: the local subarray CCO sending a silence notification to the neighboring subarray CCOs, causing the neighboring subarray CCOs to stop transmitting carrier communication signals within a preset silence duration; setting the transmit gain of the local subarray CCO to a preset minimum gain level, and performing PING communication tests on each STA in the local subarray; when there is an STA that does not meet the preset communication success conditions, gradually increasing the transmit gain until all STAs meet the preset communication success conditions; and determining the transmit power corresponding to the current transmit gain as the initial value of the current transmit power.

[0032] The initial values ​​are preferably determined when the system communication load is low and the inverter operation interference is minimal, in order to reduce the impact of other carrier signals on the initial communication test results.

[0033] Communication quality parameters include at least two of the following: received signal strength, signal-to-noise ratio, bit error rate, packet loss rate, retransmission count, and acknowledgment success rate; power line channel status parameters include at least one of the following: channel attenuation, line impedance change, and carrier received level change; external subarray carrier message statistics parameters include the subarray number carried in the carrier message, the total number of external subarray carrier messages received within a preset statistical period, and the number of carrier messages corresponding to each external subarray.

[0034] During normal system operation, the communication quality parameters of each STA communication link and the statistical parameters of external subarray carrier messages are obtained through normal service communication messages. There is no need to send dedicated link test messages, and normal data acquisition and carrier communication services do not need to be interrupted. Reference carrier signals can be sent during a preset link detection period, while crosstalk statistics and single-STA link evaluation during normal operation reuse normal service communication messages.

[0035] S2. Determine the link attenuation state corresponding to AC side power line transmission attenuation based on the power line channel state parameters, determine the cross-subarray crosstalk state and main crosstalk source subarrays based on the external subarray carrier message statistical parameters, and determine the communication quality margin of each STA communication link based on the difference between the communication quality parameters corresponding to each STA communication link and the preset reliable communication conditions.

[0036] The determination of the link attenuation state includes: controlling the carrier communication module to send a reference carrier signal to the AC power line at the current transmit power, obtaining the reference carrier received level fed back by the receiver of the carrier communication link, determining the channel attenuation amount according to the attenuation relationship between the current transmit power and the reference carrier received level, and determining the link attenuation state according to the preset attenuation range to which the channel attenuation amount belongs.

[0037] The determination of cross-subarray crosstalk status and the main crosstalk source subarray includes: based on the statistical parameters of carrier packets from external subarrays, counting the total number of external subarray carrier packets received within a preset statistical period, and using the total number of external subarray carrier packets as the crosstalk value; based on the subarray number carried by each external subarray carrier packet, counting the number of carrier packets corresponding to each external subarray; when the crosstalk value exceeds the preset crosstalk threshold, determining that the cross-subarray crosstalk status has reached the preset crosstalk condition, and identifying the external subarray with the largest number of carrier packets as the main crosstalk source subarray.

[0038] Specifically, the preset statistical period can be set to 10 seconds. The CCO of this subarray accumulates the number of carrier packets from external subarrays in each statistical period. When the crosstalk value exceeds the preset crosstalk threshold, the main crosstalk source subarray is determined according to the number of carrier packets corresponding to each subarray number.

[0039] The determination of communication quality margin includes: comparing the communication quality parameters corresponding to each STA communication link with the corresponding communication quality thresholds in the preset reliable communication conditions to obtain the quality difference value corresponding to each communication quality parameter; converting each quality difference value into a normalized quality difference value that is consistent with the direction of communication quality improvement; and determining the communication quality margin of the corresponding STA communication link based on each normalized quality difference value.

[0040] S3. Generate the basic power requirement based on the link attenuation status, generate the crosstalk suppression correction based on the cross-subarray crosstalk status, and generate the corresponding link compensation based on the communication quality margin.

[0041] The generation of basic power requirements includes: dividing the link attenuation state into at least two attenuation levels and configuring a corresponding basic power requirement range for each attenuation level; and determining the basic power requirement from the corresponding basic power requirement range based on the attenuation level to which the link attenuation state belongs.

[0042] S4. Based on the basic power requirement, and according to the cross-subarray crosstalk status and communication quality margin, selectively use crosstalk suppression correction and link compensation to adjust the basic power requirement, generating the carrier communication transmit power requirement. Specifically, when the cross-subarray crosstalk status reaches a preset crosstalk condition, the CCO of this subarray sends a crosstalk notification carrying the subarray number to the main crosstalk source subarray. After completing subarray number matching, the CCO of the main crosstalk source subarray lowers the current transmit power by adjusting the crosstalk suppression correction. When the cross-subarray crosstalk status does not reach the preset crosstalk condition, it is further determined whether each STA communication link needs to increase its transmit power. When the communication quality margin of a single STA communication link is lower than the preset reliability margin, the current transmit power corresponding to that STA communication link is increased by adjusting the link compensation, while the transmit power corresponding to other STA communication links remains unchanged.

[0043] Specifically, the power increase condition of the STA communication link is determined based on the packet loss status of the STA communication link during normal business communication. When the number of packet losses in the most recent service messages exceeds the set number, or when continuous packet loss occurs, the STA communication link is determined to have reached the power increase condition.

[0044] Crosstalk notifications are sent directly from the local subarray CCO to the CCO of the main crosstalk source subarray via a carrier communication link on the AC power line, without the need for relaying through a data acquisition unit or fiber optic ring network; the crosstalk notifications carry the subarray number to be matched and can be sent in a broadcast manner without requiring a response.

[0045] The crosstalk suppression correction is the power difference between two adjacent transmit power levels. After the CCO of the main crosstalk source subarray completes the subarray numbering matching, it lowers the current transmit power by one transmit power level, but not lower than the initial value of the current transmit power, and stops repeatedly lowering the transmit power within the preset anti-repetition adjustment window.

[0046] Specifically, the anti-repeated adjustment window can be set to 30 seconds. Within this window, even if the corresponding crosstalk notification is received again, the transmit power will not be lowered again.

[0047] The link compensation amount is the power difference between two adjacent transmit power levels. When the communication quality margin of a single STA communication link is lower than the preset reliability margin, the current transmit power of the STA communication link is increased by one transmit power level, but not exceeding the preset maximum transmit power, while the transmit power of other STA communication links remains unchanged. When communication fails continuously at the preset maximum transmit power, the transmit power of the STA communication link is restored to the initial value of the current transmit power, and the increase stops within the preset lockout duration.

[0048] Specifically, the above-mentioned abnormal handling is performed when there are 10 consecutive communication failures at the highest transmission power level, and the preset lockout duration can be set to 1 hour.

[0049] S5. Based on the carrier communication transmission power requirement, determine the target transmission power of the subarray CCO and / or the target transmission power corresponding to a single STA communication link, and control the corresponding carrier communication module to transmit carrier communication signals on the AC side power line according to the target transmission power.

[0050] The determination of the target transmit power includes: pre-setting multiple transmit power levels arranged from low to high, and establishing a correspondence between transmit gain levels and transmit power levels; limiting the transmit power requirement of carrier communication, and selecting the corresponding level from the transmit power levels as the target transmit power.

[0051] After completing carrier communication according to the target transmit power, communication quality parameters and external subarray carrier message statistics parameters are acquired in subsequent statistical periods, and crosstalk status judgment and single STA communication link evaluation are repeatedly performed to achieve dynamic adjustment of transmit power.

[0052] Example 2

[0053] like Figure 2 As shown, this embodiment, based on embodiment 1, explains the specific processes of link state calculation, cross-subarray crosstalk processing, single STA link power compensation, and anomaly handling.

[0054] In this embodiment, the AC photovoltaic system includes subarray A, subarray B, and subarray C. Each subarray is equipped with one CCO, four STAs, and four inverters. Each STA is connected to its corresponding inverter. Subarrays A, B, and C are respectively configured with subarray numbers A01, B01, and C01. Each CCO distinguishes between its own subarray messages and external subarray messages based on the subarray number carried in the carrier message.

[0055] The carrier communication module has 16 preset transmit gain levels (0-15). A higher transmit gain level corresponds to a higher transmit power. Let P(g) denote the transmit power corresponding to the g-th transmit gain level, where P(g) > P(g-1). The power difference between two adjacent transmit power levels is:

[0056] ΔP(g) = P(g) - P(g-1).

[0057] The transmission gain level and the corresponding transmission power are mapped through a preset calibration table of the carrier communication module. Different models of carrier communication modules can use different transmission power calibration values.

[0058] After the system is powered on, during periods when the photovoltaic system is under light load and communication traffic is low, the initial value of the current transmit power for each subarray is determined. The CCO of this subarray sends a silence notification to the CCOs of adjacent subarrays, causing the adjacent CCOs to stop transmitting carrier communication signals for a preset silence duration. Starting from the 0th level transmit gain, the CCO of this subarray sends 10 PING test messages to each STA sequentially; if any STA fails to meet the preset communication success condition, the transmit gain is increased by one level and the test is repeated until all STAs in this subarray meet the preset communication success condition.

[0059] In this embodiment, subarrays A, B, and C meet the preset communication success conditions at the 7th, 8th, and 7th level transmit gains, respectively. Therefore, P(7), P(8), and P(7) are determined as the initial values ​​of the current transmit power of the three subarrays. Each subarray CCO also initializes the current transmit gain of each STA communication link within its subarray to the initial transmit gain of the corresponding subarray.

[0060] During normal operation, each CCO obtains communication quality parameters and external subarray carrier message statistics through normal service communication messages. It does not send dedicated test frames for crosstalk evaluation or single-STA link evaluation, nor does it interrupt data acquisition and carrier communication services of the photovoltaic power plant. Reference carrier signals are only sent during a preset link detection period to determine the transmission attenuation status of the power line channel.

[0061] Specifically, the carrier communication module transmits a reference carrier signal at the current transmit power and obtains the reference carrier received level fed back by the receiver. After converting the calibrated transmit level corresponding to the current transmit power and the reference carrier received level to the same calibration reference, the difference between the two is used as the channel attenuation.

[0062] In this embodiment, a channel attenuation of less than 20dB is defined as a low attenuation state, a channel attenuation of 20dB-35dB is defined as a medium attenuation state, and a channel attenuation of more than 35dB is defined as a high attenuation state. The basic power requirement ranges of levels 6-8, 9-11, and 12-15 are configured for the low attenuation state, medium attenuation state, and high attenuation state, respectively.

[0063] Specifically, the channel attenuation of the carrier communication link corresponding to subarray A is 28dB, which is a medium attenuation state. Therefore, the transmit power P(9) of level 9 is selected as the basic power requirement from the basic power requirement range of level 9-11.

[0064] In this embodiment, the signal-to-noise ratio (SNR) and packet loss rate are selected to determine the communication quality margin of each STA communication link. The preset reliable communication conditions are an SNR of no less than 12 dB and a packet loss rate of no more than 20%. For the i-th STA communication link, the normalized quality difference is calculated according to the following formula:

[0065] Q1,i=(SNRi-12) / 12;

[0066] Q2,i=(0.2-Ri) / 0.2;

[0067] Where SNRi represents the signal-to-noise ratio of the i-th STA communication link, and Ri represents the packet loss rate of the STA communication link in the current statistical period. The smaller of the two normalized quality differences is determined as the communication quality margin Mi of the STA communication link, i.e.:

[0068] Mi = min(Q1,i, Q2,i).

[0069] When Mi is greater than or equal to 0, it indicates that the corresponding STA communication link meets the preset reliable communication conditions; when Mi is less than 0, it indicates that the corresponding STA communication link does not meet the preset reliable communication conditions, and further judgment is needed on whether to perform link power compensation.

[0070] Each subarray CCO counts the total number of external subarray carrier packets received during normal service communication in a 10-second period, and counts the number of carrier packets corresponding to each external subarray based on the subarray number carried in the packets. In this embodiment, the preset crosstalk threshold is set to 40 frames.

[0071] Within one statistical period, the CCO of subarray A received a total of 46 frames of external subarray carrier messages, of which 31 frames carried subarray number B01 and 15 frames carried subarray number C01. Since the total number of external subarray carrier messages (46 frames) exceeds the preset crosstalk threshold of 40 frames, it is determined that the crosstalk state of subarray A has reached the preset crosstalk condition. At the same time, since the number of carrier messages from subarray B is the largest, subarray B is identified as the main source of crosstalk.

[0072] The CCO of subarray A broadcasts a crosstalk notification carrying subarray number B01 directly via a carrier communication link on the AC power line, without needing to go through a data acquisition unit or fiber optic ring network. After receiving the crosstalk notification, the CCO of subarray B matches the subarray number B01 carried in the message with its own subarray number; if the match is successful, it uses the power difference between two adjacent transmit power levels stored locally as the crosstalk suppression correction amount.

[0073] Specifically, the current transmit gain of subarray B is level 10, corresponding to a current transmit power of P(10), and its initial transmit gain is level 8, corresponding to an initial transmit power of P(8). The power difference between the current level 10 transmit power and the adjacent lower level 9 transmit power is used as the crosstalk suppression correction amount, i.e.:

[0074] ΔP down (10) = P (10) - P (9).

[0075] The carrier communication transmit power requirement of subarray B is:

[0076] P demand, B = max[P current, B - ΔP down (10), P initial, B].

[0077] Where Pcurrent and Bcurrent are the current transmit power P(10) of subarray B before crosstalk suppression, and Pinitial and Binitial are the initial transmit power P(8) of subarray B. Therefore, Pcurrent, B - ΔPdown(10) = P(9), and P(9) is higher than P(8). Thus, P(9) is determined as the carrier communication transmit power requirement of subarray B, and the transmit gain of subarray B is downgraded from level 10 to level 9.

[0078] After the downsizing is completed, subarray B enters a 30-second anti-repetition adjustment window. During this window, even if a crosstalk notification carrying subarray number B01 is received again, the transmit gain will not be downsized again; after the window ends, subarray B is allowed to perform power adjustment again based on new crosstalk notifications.

[0079] When the cross-subarray crosstalk reaches the preset crosstalk condition, cross-subarray crosstalk suppression is prioritized in this statistical period, without simultaneously increasing the power of the single STA link within this subarray. After the power reduction of subarray B, in subsequent statistical periods, the total number of external subarray carrier messages received by subarray A decreases to 24 frames, which is lower than the preset crosstalk threshold of 40 frames. At this point, it is determined whether the transmission power of each STA communication link in subarray A needs to be increased.

[0080] Specifically, in subarray A, the signal-to-noise ratio (SNR) of the communication link corresponding to STA3 is 10 dB. In the last 10 normal service communications, 3 packet losses occurred, resulting in a packet loss rate of 30%. The corresponding normalized quality difference is:

[0081] Q1,3 = (10-12) / 12 = -0.167;

[0082] Q2,3=(0.2-0.3) / 0.2=-0.5.

[0083] Therefore, the communication quality margin M3 of the STA3 communication link is -0.5, which is lower than the preset reliability margin of 0. At the same time, STA3 meets the power increase condition of having more than 2 packet losses in the last 10 communications, confirming that power compensation is needed for the STA3 communication link.

[0084] Assuming the STA3 communication link currently corresponds to the 9th level of transmit power, the power difference between P(10) and P(9) is used as the link compensation amount, and the carrier communication transmit power requirement of the STA3 communication link is determined according to the following formula:

[0085] P demand, 3 = min{max[P base, 3, P current, 3 + ΔP(10)], P maximum}.

[0086] Where Pcurrent represents the current transmit power of the STA3 communication link, 3 represents the current transmit power of the STA3 communication link, and Pmaximum represents the preset maximum transmit power corresponding to the 15th level transmit gain. Therefore, the transmit gain of the STA3 communication link is increased from the 9th level to the 10th level, while the transmit gains of the communication links corresponding to STA1, STA2, and STA4 in subarray A remain unchanged.

[0087] In this embodiment, the CCO maintains the transmission gain of each STA communication link. For carrier communication modules that include uplink and downlink power linkage, a level difference X between the uplink and downlink transmission gains can be preset. Specifically, if X is set to 1, then after the downlink transmission gain of STA3 is increased to level 10, its uplink transmission gain is synchronously adjusted to level 11; when the uplink transmission gain calculated according to the level difference exceeds level 15, level 15 is taken as the uplink transmission gain.

[0088] For STA communication links that have already reached level 15 transmit gain, the transmit power will not be increased further. If a STA communication link still experiences 10 consecutive communication failures at level 15 transmit gain, it is determined that the communication anomaly is no longer a link anomaly caused solely by insufficient transmit power, and a corresponding inverter power outage or hardware fault indication will be output.

[0089] Specifically, if the STA4 communication link fails 10 consecutive times at the 15th level of transmit gain, the transmit gain of the STA4 communication link will be restored to the initial transmit gain level 7 of subarray A, and the STA4 communication link will be locked for 1 hour. During the lockout period, the CCO can still record the service communication status of STA4, but will no longer perform transmit gain increase operations; after the lockout period ends, the communication status of STA4 will be reassessed. The above maximum power failure, recovery, and lockout mechanism can prevent the transmit power from being continuously and ineffectively increased due to inverter power outages or hardware failures.

[0090] After determining the carrier communication transmit power requirements of each adjustment object, it is first limited to the corresponding initial transmit power and the preset maximum transmit power. Then, based on the mapping relationship between transmit gain level and transmit power level, the minimum transmit power level that is not lower than the power requirement after limiting is selected from multiple transmit power levels as the target transmit power of the corresponding subarray CCO or single STA communication link.

[0091] The corresponding carrier communication module transmits carrier communication signals according to the target transmit power. After completing the adjustment of the current statistical cycle, each CCO continues to reuse subsequent normal service communication messages to obtain communication quality parameters and external subarray carrier message statistical parameters, and sequentially performs cross-subarray crosstalk judgment and single STA communication link evaluation, thereby automatically completing the dynamic adjustment of transmit power throughout the entire system operation cycle without the need for manual intervention based on the real-time output power of the inverter.

[0092] Example 3

[0093] like Figure 3As shown, this embodiment, based on Embodiments 1 and 2, describes other optional configuration methods for communication quality parameters, crosstalk statistics parameters, and transmit power levels. Except for the differences described below, the system structure, parameter acquisition method, cross-subarray crosstalk processing flow, and single-STA communication link power compensation flow of this embodiment can all be implemented with reference to Embodiments 1 and 2.

[0094] In this embodiment, the communication quality margin of each STA communication link is not limited to being determined based on the signal-to-noise ratio and packet loss rate, but can also be determined based on at least two parameters among received signal strength, bit error rate, retransmission count, and acknowledgment success rate. For parameters where a larger value indicates better communication quality, the difference between the actual parameter value and the corresponding threshold is normalized; for parameters where a smaller value indicates better communication quality, the difference between the corresponding threshold and the actual parameter value is normalized. Subsequently, the minimum value or weighted result of each normalized quality difference can be determined as the communication quality margin of the corresponding STA communication link.

[0095] The preset statistical period, crosstalk threshold, and communication anomaly detection conditions can be configured based on the number of subarrays, the frequency of normal service messages, and the communication environment of the AC power line. Specifically, the preset statistical period can be set to 5–30 seconds, and the crosstalk threshold can be determined based on the number of external subarray carrier messages normally received within the preset statistical period. The power up-adjustment condition for a single STA communication link can be determined by the number of packet losses in a preset number of service communications exceeding a set number, or the number of consecutive packet losses reaching a set number.

[0096] The transmit power levels of the carrier communication module can be set at equal intervals or non-equal intervals based on the hardware output characteristics of the carrier communication module. When performing crosstalk suppression, it is preferable to lower the current transmit power of the main crosstalk source subarray to the adjacent lower transmit power level; when performing single STA communication link compensation, it is preferable to raise the current transmit power of the corresponding link to the adjacent higher transmit power level. The anti-repetition adjustment window, preset maximum transmit power, number of consecutive communication failures, and preset lockout duration can all be pre-configured according to the field communication cycle and inverter operating characteristics.

[0097] By combining the above parameters and configuring the levels, this invention can be applied to different subarray sizes, different carrier communication modules, and different AC power line environments, while maintaining the control logic of cross-subarray crosstalk priority suppression, single STA link differential compensation, and abnormal link recovery locking unchanged.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A power adaptive method for AC photovoltaic carrier communication, characterized in that, An AC photovoltaic system comprising multiple subarrays, each subarray having a master node (CCO), several slave nodes (STAs), and an inverter, wherein the CCO and the STAs are networked in a star topology, the method comprising: S1. Establish a carrier communication link on the AC side power line of the AC photovoltaic system, control the carrier communication module to send a carrier communication signal to the AC side power line at the current transmission power, and obtain the communication quality parameters corresponding to each STA communication link, the power line channel status parameters corresponding to the carrier communication link, and the carrier message statistics parameters from the external subarray respectively. S2. Determine the link attenuation state corresponding to AC side power line transmission attenuation based on the power line channel state parameters, determine the cross-subarray crosstalk state and main crosstalk source subarrays based on the external subarray carrier message statistics parameters, and determine the communication quality margin of each STA communication link based on the difference between the communication quality parameters corresponding to each STA communication link and the preset reliable communication conditions. S3. Generate a basic power requirement based on the link attenuation state, generate a crosstalk suppression correction based on the cross-subarray crosstalk state, and generate a corresponding link compensation based on the communication quality margin. S4. Based on the basic power requirement, and according to the cross-subarray crosstalk state and the communication quality margin, selectively use the crosstalk suppression correction amount and the link compensation amount to correct the basic power requirement, thereby generating the carrier communication transmit power requirement; wherein, when the cross-subarray crosstalk state reaches a preset crosstalk condition, the CCO of this subarray sends a crosstalk notification carrying the subarray number to the main crosstalk source subarray, and after completing the subarray number matching, the CCO of the main crosstalk source subarray lowers the current transmit power by using the crosstalk suppression correction amount as the adjustment range; when the communication quality margin of a single STA communication link is lower than a preset reliability margin, the current transmit power corresponding to the STA communication link is increased by using the link compensation amount as the adjustment range, while the transmit power corresponding to other STA communication links remains unchanged; S5. Based on the carrier communication transmission power requirement, determine the target transmission power of the subarray CCO and / or the target transmission power corresponding to a single STA communication link, and control the corresponding carrier communication module to transmit carrier communication signals on the AC side power line according to the target transmission power.

2. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The communication quality parameters include at least two of the following: received signal strength, signal-to-noise ratio, bit error rate, packet loss rate, retransmission count, and acknowledgment success rate; the power line channel status parameters include at least one of the following: channel attenuation, line impedance change, and carrier received level change; the carrier message statistics parameters of the external subarrays include the subarray number carried by the carrier message, the total number of external subarray carrier messages received within a preset statistical period, and the number of carrier messages corresponding to each external subarray.

3. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The determination of the link attenuation state includes: controlling the carrier communication module to send a reference carrier signal to the AC power line at the current transmit power, obtaining the reference carrier received level fed back by the receiver of the carrier communication link, determining the channel attenuation amount according to the attenuation relationship between the current transmit power and the reference carrier received level, and determining the link attenuation state according to the preset attenuation range to which the channel attenuation amount belongs.

4. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The determination of the initial value of the current transmit power includes: the local subarray CCO sending a silence notification to the adjacent subarray CCO, causing the adjacent subarray CCO to stop transmitting carrier communication signals within a preset silence duration; setting the transmit gain of the local subarray CCO to a preset minimum gain level, and performing PING communication tests on each STA in the local subarray; when there is an STA that does not meet the preset communication success conditions, gradually increasing the transmit gain until all STAs meet the preset communication success conditions; and determining the transmit power corresponding to the current transmit gain as the initial value of the current transmit power.

5. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The determination of the communication quality margin includes: comparing the communication quality parameters corresponding to each STA communication link with the corresponding communication quality threshold in the preset reliable communication conditions to obtain the quality difference value corresponding to each communication quality parameter; converting each quality difference value into a normalized quality difference value that is consistent with the direction of communication quality improvement; and determining the communication quality margin of the corresponding STA communication link based on each normalized quality difference value.

6. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The generation of the basic power demand includes: dividing the link attenuation state into at least two attenuation levels and configuring a corresponding basic power demand range for each attenuation level; and determining the basic power demand from the corresponding basic power demand range according to the attenuation level to which the link attenuation state belongs.

7. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The determination of the cross-subarray crosstalk state and the main crosstalk source subarray includes: based on the carrier packet statistical parameters from the external subarray, counting the total number of external subarray carrier packets received within a preset statistical period, and using the total number of external subarray carrier packets as the crosstalk value; based on the subarray number carried by each external subarray carrier packet, counting the number of carrier packets corresponding to each external subarray; when the crosstalk value exceeds a preset crosstalk threshold, determining that the cross-subarray crosstalk state has reached the preset crosstalk condition, and determining the external subarray with the largest number of carrier packets as the main crosstalk source subarray.

8. The adaptive power method for AC photovoltaic carrier communication according to claim 4, characterized in that: The crosstalk suppression correction is the power difference between two adjacent transmit power levels; after the CCO of the main crosstalk source subarray completes the subarray number matching, it lowers the current transmit power by one transmit power level, and not lower than the initial value of the current transmit power, and stops repeatedly lowering the transmit power within the preset anti-repetition adjustment window.

9. The adaptive power method for AC photovoltaic carrier communication according to claim 4, characterized in that: The link compensation amount is the power difference between two adjacent transmit power levels. When the communication quality margin of a single STA communication link is lower than the preset reliability margin, the current transmit power of the STA communication link is increased by one transmit power level, but not exceeding the preset maximum transmit power, while the transmit power of other STA communication links remains unchanged. When communication fails continuously at the preset maximum transmit power, the transmit power of the STA communication link is restored to the initial value of the current transmit power, and the increase stops within the preset lockout duration.

10. The adaptive power method for AC photovoltaic carrier communication according to claim 1, characterized in that: The determination of the target transmission power includes: pre-setting multiple transmission power levels arranged from low to high, and establishing a correspondence between the transmission gain level and the transmission power level; limiting the transmission power requirement of the carrier communication, and selecting the corresponding level from the transmission power levels as the target transmission power.

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