A distributed anti-inversion communication architecture of inverter and working method thereof

Abstract

The application discloses a distributed anti-inrush communication architecture of inverters and a working method thereof. The architecture comprises a power meter, K data collectors and multiple inverters connected to a power grid. The multiple inverters are divided into K groups according to a set requirement, and K is greater than or equal to 2. Each data collector collects real-time data and issues instructions to a corresponding group of inverters. The K data collectors are sequentially connected in one-way anti-inrush communication to form a one-way closed loop communication topology. The power meter is connected in communication with the one-way closed loop communication topology, and the power meter is adapted to transmit a detected anti-inrush signal to each data collector through the one-way closed loop communication topology. The application has the advantages of strong communication synchronization, consistent anti-inrush response, full use of communication resources and local computing resources, effective avoidance of control competition in the case of asynchronous or inconsistent data of multiple data collectors, ensured consistency of anti-inrush scheduling decisions in the whole network, and improved concurrent processing capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy power generation technology, in particular to a distributed inverter anti-flow communication architecture and a working method thereof. BACKGROUND

[0002] In the prior art, under different scales and arrangement conditions, anti-flow control is generally divided into three typical forms, and star and ring network are commonly used as network forming modes for data acquisition and transmission.

[0003] In small stations, the number of inverters is small and the capacity is limited, and an anti-flow meter (such as a bidirectional meter or a CT meter) is directly communicated with each inverter through RS-485 to detect the active power “returned to the grid side” in real time and trigger the inverter to switch from MPPT to power limiting mode, so as to press the output to near zero. This method has short link and simple structure, and does not need to configure a data collector to complete the basic anti-flow control.

[0004] When the number of inverters rises to a small or medium scale, the industry generally adopts a single data collector + star access: the anti-flow meter is connected to a centralized data collector, the collector polls the data of each inverter and meter through RS-485 bus or power carrier (MBUS / PLC) at the same time, completes the anti-flow decision locally and uniformly issues power instructions to all inverters to realize coordinated control of the whole station. At this time, the uplink usually goes through Ethernet / optical fiber to the switch to form a star convergence; the downlink is branched out to the equipment through multi-channel RS-485 or MBUS for easy deployment and centralized management, but is limited by the bus bandwidth and single machine processing capacity, and the applicable scale is still limited.

[0005] When the power station is further expanded and the single machine collection capacity becomes a bottleneck, the existing system is often converted to a master-slave architecture of multiple data collectors, and a ring network or star optical fiber network is used between collectors to improve reliability and coverage: the master collector is connected to the anti-flow meter and the upper EMS, periodically collects the inverter and meter data reported by multiple slave collectors, centrally executes the anti-flow algorithm and issues control instructions; the collectors often form a ring network by themselves with two optical ports or form a star convergence through a switch, while each collector is still connected to the inverters and metering / environmental equipment through RS-485 or MBUS.

[0006] However, for multi-inverter large-capacity station, a single data collector is limited by communication distance and processing capacity, and it is difficult to cover the whole station, and the system scalability is poor. The existing data collection master-slave architecture has common defects under star and ring network: end-to-end delay and jitter are difficult to control, and cross-node consistency is poor; ring network messages are aggregated to the host hop by hop, and the near-end link and node are long-term overloaded, and the far-end resource is idle, and the utilization rate is unbalanced; the master-slave communication often relies on the cloud to complete the anti-flow calculation and then issues, which increases the backhaul and cloud-side uncertainty, and the required communication time is longer, and the local computing power is not fully utilized. SUMMARY

[0007] One of the purposes of the present application is to provide a distributed inverter anti-flow communication architecture which can solve at least one of the defects in the background art.

[0008] Another purpose of the present application is to provide a working method of a distributed inverter anti-flow communication architecture which can solve at least one of the defects in the background art.

[0009] To achieve the above at least one purpose, the technical scheme adopted by the present application is: a distributed inverter anti-flow communication architecture, comprising a power meter, a data collector and a plurality of inverters connected to a power grid; the plurality of inverters are divided into K groups according to the set requirements, K≥2; the number of data collectors is K, each data collector collects real-time data and issues instructions to the corresponding group of inverters, and the K data collectors are sequentially connected in one-way communication, thereby forming a one-way closed ring communication topology; the power meter is in communication connection with the one-way closed ring communication topology, and the power meter is adapted to transmit the detected anti-flow signal to each data collector through the one-way closed ring communication topology.

[0010] Preferably, the identification of the data packet sent by each data collector is different; a data transmission period starts from a single data collector sending an identification data packet to the one-way closed ring communication topology, and ends when the identification data packet sent by itself is received again.

[0011] Preferably, a single data transmission period includes K consecutive data transmission stages; the data collector is adapted to complete the processing and packaging of its own data in the first K-1 data transmission stages to form the identification data packet of the next data transmission period, and then update the identification data packet of the current loop based on the identification data packet of the next data transmission period when performing the loop of its own data in the Kth data transmission stage.

[0012] Preferably, one of the data collectors is in communication connection with the electric meter; when the electric meter detects a reverse flow signal, the data collector connected with the electric meter appends a reverse flow detection flag in the identification data packet of the data collector, and then transmits the reverse flow detection flag to each of the data collectors in a single data transmission cycle.

[0013] Preferably, the identification data of the data collector comprises a frame header, a variable area, a load area and a frame tail; the frame header is used to carry protocol identification, length and addressing information, the variable area is used to carry synchronization related information, the load area is used to carry service data, and the frame tail is used for frame level integrity check.

[0014] Preferably, after receiving the data sent by the previous data collector, the data collector waits for a set time to forward the data to the next data collector; and the variable area is adapted to record and carry time limit control information required for the set time waiting for data forwarding.

[0015] Preferably, the time limit control information carried by the variable area at each data forwarding includes the forwarding times of the current data, the waiting time for data forwarding by the previous data collector, and the receiving time of the data received by the previous data collector; when the data collector receives the current data, the set time required for the current data collector to wait is calculated by the local receiving time, the waiting time for data forwarding by the previous data collector recorded in the variable area, and the receiving time of the data received by the previous data collector.

[0016] A working method of the distributed anti-reverse flow communication architecture of the inverter, comprising the following steps: when one of the data collectors identifies a reverse flow signal, the reverse flow signal is transmitted to all the data collectors in a data transmission cycle through a unidirectional closed loop communication topology; and all the data collectors synchronously send a power reduction signal for anti-reverse flow control to all the inverters at a selected time reference.

[0017] Preferably, based on the data transmission cycle of the reverse flow signal transmission, the starting time of the next data transmission cycle is taken as the selected time reference; or the identification data loop time of the data collector identifying the reverse flow signal is delayed by a fixed time as the selected time reference.

[0018] Preferably, when performing anti-reverse flow control, each data collector calculates the anti-reverse flow load reduction power required to be borne by the inverter responsible for itself based on the global power data in the data transmission cycle according to the local power generation power ratio, and then evenly distributes the calculated anti-reverse flow load reduction power to each inverter responsible for itself to obtain the required power reduction signal.

[0019] Compared with the prior art, the application has the beneficial effects that:

[0020] The application has strong communication synchronization, consistent anti-backflow response, full use of communication resources and local computing resources. The identification data loop is taken as the cycle boundary, and the anti-backflow event is synchronized to all nodes in a flag mode, effectively avoiding control competition in the case of asynchronous or inconsistent data of multiple data collectors, ensuring consistent anti-backflow scheduling decision of the whole network, and improving concurrent processing capability. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the basic architecture of the application.

[0022] Figure 2 The figure is a schematic diagram of the architecture of a complete data transmission cycle in the application.

[0023] Figure 3 The figure is a schematic diagram of the working timing of the data collector in a single data transmission cycle in the application.

[0024] Figure 4 The figure is a schematic diagram of the transmission of the anti-backflow flag by the data collector in the application.

[0025] Figure 5 The figure is a schematic diagram of the structure of the identification data packet in the application.

[0026] In the figure: inverter 100, electric meter 200, data collector 300, power grid 400, switch 500, network manager 600. DETAILED DESCRIPTION

[0027] In the following, the application will be further described in conjunction with specific embodiments. It should be noted that in the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present application.

[0028] In the description of the application, it should be noted that for orientation words, such as the terms "center", "transverse", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation and positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and cannot be understood as limiting the specific protection scope of the application.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0030] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be connected, or it can be detachable, or it can be integrated; it can be mechanical connection, or it can be electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0032] The terms "include" and "have" in the specification and claims of the present application, as well as any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] One aspect of the present application provides a distributed inverter anti-flow communication architecture, such as Figure 1The preferred embodiment shown includes an electric meter 200, K data collectors 300, and a plurality of inverters 100 connected to the power grid 400. The plurality of inverters 100 are divided into K groups according to the set requirements, K≥2. Each data collector 300 collects real-time data and issues instructions to the corresponding group of inverters 100, and the K data collectors 300 are sequentially connected in a one-way anti-flow communication connection to form a one-way closed loop communication topology. The electric meter 200 is in communication connection with the one-way closed loop communication topology, and the electric meter 200 can transmit the detected anti-flow signal to each data collector 300 through the one-way closed loop communication topology.

[0034] It can be understood that the distributed inverter anti-flow communication architecture based on the one-way closed loop communication topology provided by the present application can achieve efficient cooperation between the plurality of data collectors 300 and improve the robustness of the entire communication architecture. Specifically, by dividing the plurality of inverters 100 in the entire station into K groups, each group is responsible for collecting the operating data of the inverters 100 in the group by one data collector 300, and the data collectors 300 are connected to each other through the one-way closed loop communication topology and sequentially transmit the locally collected and received global data in a fixed order. It is ensured that each data collector 300 can completely obtain the anti-flow state information collected by the inverters 100 and the electric meter 200 in the entire station. Each data collector 300 independently judges and issues power regulation instructions based on the global information to achieve distributed anti-flow control.

[0035] Compared with the traditional method, the communication synchronization of the present application is strong, the anti-flow response is consistent, and the communication resources and local computing resources are fully utilized. The identification data loop is taken as the cycle boundary, and the anti-flow event is synchronized to all nodes in a flag manner, which effectively avoids control competition in the case of asynchronous or inconsistent data of the plurality of data collectors 300, ensures that the anti-flow scheduling decision is consistent in the entire network, and effectively improves the concurrent processing capability. At the same time, each data collector 300 only needs to collect data of the inverters 100 in the group and only needs to forward to the next data collector 300, so the data packet volume transmitted in the one-way closed loop communication topology is small and the forwarding path is short; and each data collector 300 has complete global perception and independent decision-making capability.

[0036] It should be understood that the specific grouping method of the plurality of inverters 100 can be allocated according to the principles of geographical location or similar capacity; the plurality of inverters 100 can be connected to the power grid 400 in series and / or parallel. The specific number of inverters 100 in each group can be selected by the person skilled in the art according to the actual needs; for the convenience of understanding, a specific example will be described in detail below.

[0037] Specifically, as shown in FIG. 1, the plurality of inverters 100 are divided into K groups, K≥2, and each group is responsible for collecting the operating data of the inverters 100 in the group by one data collector 300. The K data collectors 300 are sequentially connected in a one-way anti-flow communication connection to form a one-way closed loop communication topology. The electric meter 200 is in communication connection with the one-way closed loop communication topology, and the electric meter 200 can transmit the detected anti-flow signal to each data collector 300 through the one-way closed loop communication topology. Figure 1As shown, the 11 inverters 100 can be divided into 4 groups, i.e. K=4; wherein one group includes 2 inverters 100, and the other 3 groups each include 3 inverters 100. The 4 groups of inverters 100 can be sequentially marked as inverter group #1 to #4, wherein the inverter group #1 includes 2 inverters 100, then the 2 inverters 100 of the inverter group #1 can be marked as inverter #1-1 and inverter #1-2; similarly, the 3 inverters 100 of the inverter group #2 can be marked as inverter #2-1, inverter #2-2 and inverter #2-3 respectively; the 3 inverters 100 of the inverter group #3 can be marked as inverter #3-1, inverter #3-2 and inverter #3-3 respectively; and the 3 inverters 100 of the inverter group #4 can be marked as inverter #4-1, inverter #4-2 and inverter #4-3 respectively. Correspondingly, the number of data collectors 300 is also set to 4, the data collector 300 corresponding to the inverter group #1 can be marked as data collector #1, the data collector 300 corresponding to the inverter group #2 can be marked as data collector #2, the data collector 300 corresponding to the inverter group #3 can be marked as data collector #3, and the data collector 300 corresponding to the inverter group #4 can be marked as data collector #4.

[0038] It should be understood that the 4 data collectors 300 are connected in sequence end to end through the communication link to form a unidirectional closed ring topology, realizing the directional and sequential transmission of data packets among the data collectors 300; the specific mode of the communication link can be selected by the person skilled in the art according to actual needs, for example, an optical fiber can be used. The data packets generated by the data collectors 300 always flow unidirectionally in the ring link, ensuring system synchronization and clear structure, and effectively supporting distributed synchronization decision and anti-backflow response.

[0039] It should be understood that, in order to ensure the safe operation of the distributed inverter system, all inverters 100 need to be synchronized to perform anti-backflow power regulation when backflow occurs. Since the data packets are transmitted unidirectionally in the unidirectional closed ring communication topology, when one of the data collectors 300 collects a backflow signal, the data packet carrying the backflow signal needs to be transmitted to each data collector 300, and after the transmission of the backflow signal is completed, each data collector 300 needs a synchronous time reference for anti-backflow control; therefore, a clear data transmission period needs to be set. That is, the backflow signal needs to be transmitted within a single data transmission period, and then the appropriate opportunity is selected to control all inverters 100 for anti-backflow. There are many specific ways to set the data transmission period, in order to facilitate understanding, a specific setting method of the data transmission period will be given below.

[0040] Specifically, as shown in FIG. 4, the data transmission period is set to 4 data transmission cycles, i.e. the data transmission period is set to 4 times the data transmission cycle. Figure 2As shown, the data packets sent by each data collector 300 have different identifiers; a data transmission cycle is defined as the period from when a single data collector 300 sends an identifier data packet to a unidirectional closed-loop communication topology until it receives its own identifier data packet again.

[0041] For ease of understanding, the following will use the aforementioned four data collectors #1 to #4 as examples to describe a single data transmission cycle in detail. For ease of description, the data packet generated by data collector #1 can be identified as data #1, the data packet generated by data collector #2 as data #2, the data packet generated by data collector #3 as data #3, and the data packet generated by data collector #4 as data #4.

[0042] like Figure 2 As shown, at the beginning of the data transmission cycle, data collector #1 receives data #4 and sends its own generated data #1 to data collector #2. Data collector #2 receives data #1 and sends its own generated data #2 to data collector #3. Data collector #3 receives data #3 and sends its own generated data #3 to data collector #4. Data collector #4 receives data #3 and sends its own generated data #4 to data collector #1.

[0043] In the second phase, data collector #1 forwards the data #4 received in the initial phase to data collector #2, data collector #2 forwards the data #1 received in the initial phase to data collector #3, data collector #3 forwards the data #2 received in the initial phase to data collector #4, and data collector #4 forwards the data #3 received in the initial phase to data collector #1.

[0044] In the third stage, data collector #1 forwards the data #3 received in the previous stage to data collector #2, data collector #2 forwards the data #4 received in the previous stage to data collector #3, data collector #3 forwards the data #1 received in the previous stage to data collector #4, and data collector #4 forwards the data #2 received in the previous stage to data collector #1.

[0045] In the final stage, data collector #1 forwards data #2 received in the previous stage to data collector #1, data collector #2 forwards data #3 received in the previous stage to data collector #3, data collector #3 forwards data #4 received in the previous stage to data collector #4, and data collector #4 forwards data #1 received in the previous stage to data collector #1.

[0046] After going through the four stages, the identification data packet generated by each data collector 300 at the starting stage will go through the nodes formed by the remaining three data collectors 300 and finally return to the original sender, realizing the loop of the data packet. At this time, each data collector 300 immediately enters the next new data transmission period, re-collects and encapsulates the local new data, and starts a new round of data flow. Through this communication mode of dividing the period by the loop of its own data, the synchronization of the whole network data and the complete perception of each data collector 300 to the whole station data are ensured, which is convenient for realizing the consistency of distributed decision and anti-backflow control.

[0047] It should be noted that in order to ensure the continuity of the data transmission period, each data collector 300 needs to complete the packaging of the local new data of the next data transmission period before the end of the current data transmission period after completing the delivery of its own identification data packet at the starting stage of the current data transmission period, so that the data collector 300 can immediately deliver a new identification data packet at the starting stage of the next data transmission period.

[0048] Specifically, each data collector 300 is not only responsible for real-time data collection of the local inverter 100, but also needs to perform necessary data cleaning, preprocessing and formatting packaging operations on the collected raw data to ensure accurate and standardized data. As soon as the identification data packet of the current data transmission period is sent, the data collection and packaging process of the next data transmission period is started, and the new round of data arrangement and preparation is completed in advance before the current identification data packet is looped back to the local machine. When the next data transmission period starts, the data collector 300 can immediately encapsulate the latest and complete local data as a new identification data packet and send it to the next node. The data types contained in the identification data packet are various, some of which are constant data and some of which are variable data; therefore, when packaging the identification data packet corresponding to the next data transmission period, only the variable data of the identification data packet of the current data transmission period can be updated, thereby improving the packaging efficiency of the data.

[0049] It can be understood that, as known from the foregoing, a single data transmission period includes K consecutive data transmission stages; the data collector 300 can complete the processing and packaging of its own data in the first K-1 data transmission stages to form the identification data packet of the next data transmission period, and then update the looped identification data packet based on the identification data packet of the next data transmission period when looping its own data in the Kth data transmission stage. For ease of understanding, the following will take data collector #1 as an example to describe the delivery and updating process of its own identification data packet in detail.

[0050] Specifically, as Figure 2 and Figure 3As shown, according to the foregoing, a single data transmission cycle can be divided into four data transmission stages, i.e., a starting stage, a second stage, a third stage and a final stage, according to the number of data collectors 300.

[0051] At the starting moment of the starting stage, the data collector #1 can receive the data #4 and send the local data #1 to the data collector #2; during the entire starting stage, the data collector #1 will process the received data #4, such as data identification, and prepare for forwarding; the data collector #1 can also receive and process the data of the inverter 100 of the group in real time during this stage.

[0052] At the starting moment of the starting stage, the data collector #1 can receive the data #4 and send the local data #1 to the data collector #2; during the entire starting stage, the data collector #1 will process the received data #4, such as data identification, and prepare for forwarding; the data collector #1 can also receive and process the data of the inverter 100 of the group in real time during this stage.

[0053] At the starting moment of the starting stage, the data collector #1 can receive the data #4 and send the local data #1 to the data collector #2; during the entire starting stage, the data collector #1 will process the received data #4, such as data identification, and prepare for forwarding; the data collector #1 can also receive and process the data of the inverter 100 of the group in real time during this stage.

[0054] At the starting moment of the starting stage, the data collector #1 can receive the data #4 and send the local data #1 to the data collector #2; during the entire starting stage, the data collector #1 will process the received data #4, such as data identification, and prepare for forwarding; the data collector #1 can also receive and process the data of the inverter 100 of the group in real time during this stage.

[0055] It should be appreciated that the reverse current of the distributed inverter system can be detected by the electric meter 200 arranged between the power grid 400 and the inverters 100, i.e. the electric meter 200 considers that the reverse current occurs when it detects the reverse active power; the specific identification process of the reverse current signal by the electric meter 200 is known to those skilled in the art, and thus will not be described in detail herein. When the electric meter 200 detects the reverse current signal, it needs to communicate with the data collector 300 to inform, and the electric meter 200 can communicate with all the data collectors 300 or communicate with part of the data collectors 300. Since the reverse current prevention control needs to be operated synchronously by all the inverters 100, in order to ensure the synchronization, the reverse current signal needs to flow along the unidirectional closed loop communication topology for one round, and thus the electric meter 200 only needs to be connected in communication with one data collector 300. When the electric meter 200 detects the reverse current, the identification data packet of the data collector 300 connected with the electric meter 200 is attached with a reverse current detection flag, and then the reverse current detection flag is transmitted to each data collector 300 through a single data transmission cycle.

[0056] It should be appreciated that the electric meter 200 can be connected in communication with any one data collector 300, and in the embodiment, the electric meter 200 is preferably connected in communication with the data collector 300 with the least number of inverters 100 in the corresponding group. For example Figure 1 As shown in the figure, the number of inverters 100 contained in the inverter group #1 corresponding to the data collector #1 is the least, and thus the electric meter 200 can be connected in communication with the data collector #1. Then when the electric meter 200 detects the reverse current signal, the reverse current detection flag can be attached in the data #1. In order to facilitate understanding, the specific process of the reverse current detection flag cycle of the data collector #1 connected with the electric meter 200 will be described in detail below.

[0057] Specifically, as shown in the figure Figure 4 In the Nth data transmission cycle, if the data collector #1 detects that the electric meter 200 has the reverse current, i.e. the current flows to the power grid 400 when the local data is collected, then in the subsequent N+1th data transmission cycle, the data collector #1 attaches the reverse current detection flag in the identification data packet sent by it. The data #1 containing the reverse current detection flag Figure 4The winning red) along the one-way closed ring communication topology in turn through the data collector #2, #3, #4, while each data collector 300 also complete their own data packet synchronization forwarding, to achieve the network data synchronization. The start standard of the anti-backflow algorithm is that each data collector 300 receives a data packet with an anti-backflow detection flag, and the identification data packet has been looped back to the local machine, ensuring that all data collectors 300 make decisions and responses with the same global data view. That is, at the end of the N+1 data transmission cycle, each data collector 300 synchronously starts the anti-backflow algorithm and immediately issues corresponding control instructions to the inverters 100 under its jurisdiction, ensuring that the anti-backflow measures are uniform throughout the network and timely, avoiding scheduling conflicts and inconsistencies in distributed stations due to asynchronous data.

[0058] In this embodiment, the specific structure type of the identification data packet of the data collector 300 has multiple types. In order to facilitate understanding, one specific structure will be described in detail below. As shown in Figure 5 The identification data of the data collector 300 includes a frame header, a variable area, a load area, and a frame tail. Among them, the frame header is a general control and analysis entry, used to carry protocol identification, length, and necessary addressing information, to ensure that the receiving party can quickly locate and correctly interpret the subsequent content. The variable area is used to carry synchronization related information, which is a unique extension area of the technical solution of the present application, and it can be updated in the forwarding process of the data packet. The load area is used to carry business data, such as power, voltage / frequency, state and event summary, etc. The frame tail is used for frame level integrity check, and authentication tags can be added as necessary without affecting the organization form of the above-mentioned sections. Compared with the traditional way, the overall structure of the identification data packet of the present application can realize the function of data forwarding synchronization only by increasing the variable area without changing the conventional data frame analysis habit.

[0059] It should be known that, in order to avoid the influence caused by uncontrollable data forwarding delay on the synchronization of forwarding and communication after accumulation, the data collector 300 needs to wait for a fixed time after receiving the data before forwarding. That is, the data collector 300 waits for a set time to forward the data to the next data collector 300 after receiving the data sent by the previous data collector 300. Considering that the distributed inverter system is often installed in an outdoor environment and lacks corresponding networking capability, which makes it impossible for the data collectors 300 to be networked and synchronized in time, the total forwarding delay time of the data packet in the entire data transmission cycle can be set. In simple terms, the waiting time required for data forwarding is T in theory. In a data transmission cycle, the data needs to be forwarded K times, and theoretically the waiting time of each time needs to be controlled to T. However, due to the difficulty in synchronizing the time between the data collectors 300, the setting of the single waiting time T may cause time synchronization disorder; therefore, in the technical solution of the present application, the total waiting time of the data packet in a data transmission cycle can be set to KT, and the waiting time of single forwarding does not need to be set; in this way, only the waiting time needs to be confirmed when the local loop is looped.

[0060] It should be known that, in order to ensure that the total waiting time of the data packet at the end of the single data transmission cycle meets the set value requirement, the variable area of the data packet can be designed, that is, the variable area can record and carry the time limit control information required for the waiting set time of data forwarding, so that the control information of "forwarding within a limited time after receiving" can be transmitted to the next data collector 300 with the packet under the condition of no full network time synchronization. Further, the forwarding waiting time of the previous node is calculated when the data is forwarded to the next node, and the forwarding waiting time of the current stage is adjusted according to the calculation result.

[0061] Specifically, the time limit control information carried by the variable area at each data forwarding includes the forwarding times of the current data, the waiting time of the previous data collector 300 for data forwarding, and the receiving time of the previous data collector 300 for receiving the data. When the data collector 300 receives the current data, the set time required for the current data collector 300 to wait is calculated by the local receiving time and the waiting time of the previous data collector 300 for data forwarding and the receiving time of the previous data collector 300 for receiving the data recorded in the variable area; thereby the end-to-end delay in the multi-stage propagation process of the data is converged to the vicinity of the expected target.

[0062] It can be understood that the set time required for the current data collector 300 to wait can be defined as the current node waiting time, the waiting time for the last data collector 300 to forward data can be defined as the last node waiting time, and the actual waiting time for the last data collector 300 to forward data can be defined as the actual time consumed by the last node. Then the current node waiting time = set waiting time - (actual time consumed by the last node - last node waiting time). For the convenience of understanding, the following will be explained by specific parameters.

[0063] Specifically, it is assumed that the receiving time of data transmitted to the local receiving time is t A , that is, the local receiving time is t A , and the receiving time of the last data collector 300 receiving the data is t B . The identification time of the data in the last data collector 300 is T1, the actual waiting time of the last data collector 300 forwarding data is T2, that is, the actual time consumed by the last node is T2, and the time of data transmitted from the last data collector 300 to the local time is T3. Then t A -t B = T1+ T2+ T3. Among them, T1 and T3 are known data, so T2 can be directly calculated.

[0064] Since the theoretical waiting time of data forwarding, that is, the set waiting time, is a constant T, the current node waiting time T4´=T-(T2-T4) can be calculated. Wherein T4 represents the last node waiting time stored in the variable area of the identification data packet. After completing the calculation of the current node waiting time T4´, the last node waiting time of the variable area of the identification data packet is updated.

[0065] More specifically, it is assumed that the value of T is 10ms, if the last node waiting time T4 is 8ms, and the actual time consumed by the last node T2 is 10ms, then the current node waiting time T4´ calculated is 8ms, that is, the local data forwarding is 2ms ahead of the theoretical waiting time. If the actual time consumed by the current node T2´ is 7ms, then the next node waiting time T4〞=T-(T2´-T4´)=11ms, that is, the waiting time of the next node forwarding data is 1ms delayed compared with the theoretical waiting time.

[0066] In a popular way, the actual time consumed by the last node can be calculated by subtracting the local receiving time from the receiving time of the last data collector 300 receiving the data

[0067] Compared with the traditional method, in the anti-backflow and cooperative control scene of the application, the variable area of the data packet can ensure that each data collector 300 obtains a stable and controllable time window in the fixed process of "receiving-computing-waiting-forwarding", and has a self-recovery trend for abnormal links; with minimal protocol changes, the synchronization function is realized.

[0068] In this embodiment, as shown in Figure 1 The distributed inverter anti-backflow communication architecture of the application further includes a switch 500, which can be in communication connection with the unidirectional closed loop communication topology and is in bypass mirror mode and does not participate in data forwarding. In the process of transmitting data packets from upstream to downstream in the unidirectional closed loop communication topology, the switch 500 can monitor data by mirroring and the like, and upload the monitored data to the network manager 600, so as to enable the user to view the working state of the distributed inverter system.

[0069] Another aspect of the application provides a working method of the above-mentioned distributed inverter anti-backflow communication architecture, wherein a preferred embodiment includes the following steps: when one of the data collectors 300 identifies an anti-backflow signal, the anti-backflow signal is transmitted to all the data collectors 300 within one data transmission period through the unidirectional closed loop communication topology; all the data collectors 300 synchronously transmit the power reduction signal for anti-backflow control to all the inverters 100 at the selected time reference.

[0070] It can be understood that when performing anti-backflow control, each data collector 300 calculates the anti-backflow load reduction power required to be borne by the inverters 100 responsible for it according to the local power generation power ratio based on the global power data within the data transmission period, and then evenly distributes the calculated anti-backflow load reduction power to each inverter 100 responsible for it to obtain the required power reduction signal. For the convenience of understanding, the following will take data collector #1 as an example for detailed description.

[0071] Specifically, it is assumed that the total power generation power of the inverter #1-1 and the inverter #1-2 responsible for the data collector #1 accounts for 10% of the local power generation power; if the power levels of the inverter #1-1 and the inverter #1-2 are the same, then the anti-backflow load reduction power required to be borne by the inverter #1-1 and the inverter #1-2 is 5%ΔP, wherein ΔP represents the total global anti-backflow load reduction power; if the power levels of the inverter #1-1 and the inverter #1-2 are different, and the power level of the inverter #1-1 is 1.5 times that of the inverter #1-2, then the anti-backflow load reduction power required to be borne by the inverter #1-1 is 6%ΔP, and the anti-backflow load reduction power required to be borne by the inverter #1-2 is 4%ΔP.

[0072] It should be noted that in the technical solution of the present application, there is a strong synchronization mechanism for data forwarding, so the anti-backflow instructions issued by each data collector 300 to the corresponding inverter 100 need to be synchronized with the set time reference. There are various ways to select the time reference; for example, based on the data transmission cycle of the backflow signal transmission, the start time of the next data transmission cycle is selected as the selected time reference; or the identification data loop time of the data collector 300 that identifies the inverter signal is delayed by a fixed time as the selected time reference.

[0073] Specifically, for the start time of the next data transmission cycle as the selected time reference, as shown in Figure 4 from the detection of backflow by data collector #1 and the sending of data #1 containing the backflow detection flag to the end of the third phase of the current data transmission cycle, data collectors #2 to #4 all receive data #1 containing the backflow detection flag; in the last phase of the current data transmission cycle, the four data collectors 300 can complete the preparation of the anti-backflow instruction and issue it at the start time of the next data transmission cycle.

[0074] For the identification data loop time of the data collector 300 that identifies the inverter signal is delayed by a fixed time as the selected time reference. From the detection of backflow by data collector #1 and the sending of data #1 containing the backflow detection flag to the reception of data #1 containing the backflow detection flag again, the anti-backflow instruction is issued after a delay of 0.25t, 0.5t or t to ensure that each data collector 300 has sufficient time to prepare the anti-backflow instruction; where t represents the duration of a single data transmission cycle.

[0075] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A distributed inverter anti-backflow communication architecture, characterized in that, include: Multiple inverters connected to the power grid; the multiple inverters are divided into K groups according to set requirements, where K≥2; the number of inverters in each group is greater than or equal to 2; as well as K data acquisition units; each data acquisition unit performs real-time data acquisition and command issuance to a corresponding set of inverters; the K data acquisition units sequentially establish unidirectional communication connections to form a unidirectional closed-loop communication topology. An electricity meter is communicatively connected to the unidirectional closed-loop communication topology, and the electricity meter is adapted to transmit the detected reverse current signal to each of the data acquisition units through the unidirectional closed-loop communication topology; Each of the data acquisition devices sends data packets with different identifiers; a data transmission cycle begins when a single data acquisition device sends an identifier data packet to the unidirectional closed-loop communication topology and ends when it receives its own identifier data packet again. A single data transmission cycle comprises K consecutive data transmission phases; The data collector is adapted to process and package its own data in the first K-1 data transmission stages to form the identification data packet for the next data transmission cycle, and then update the identification data packet of the current loop based on the identification data packet of the next data transmission cycle when performing its own data loopback in the Kth data transmission stage.

2. The distributed inverter anti-reverse current communication architecture as described in claim 1, characterized in that, One of the data acquisition devices is connected in communication with the electricity meter; When the electricity meter detects a reverse current signal, a reverse current detection flag is added to the identification data packet of the data acquisition device connected to the electricity meter, and then the reverse current detection flag is transmitted to each of the data acquisition devices through a single data transmission cycle.

3. The distributed inverter anti-reverse current communication architecture as described in claim 1 or 2, characterized in that, The identification data of the data acquisition device includes frame header, variable area, load area and frame tail; The frame header carries the protocol identifier, length, and addressing information; the variable area carries synchronization-related information; the payload area carries service data; and the frame tail is used for frame-level integrity verification.

4. The distributed inverter anti-reverse current communication architecture as described in claim 3, characterized in that, After receiving data from the previous data collector, the data collector waits for a set time before forwarding the data to the next data collector; the variable area is adapted to record and carry time-limited control information for the set waiting time required for data forwarding.

5. The distributed inverter anti-reverse current communication architecture as described in claim 4, characterized in that, The time-limited control information carried by the variable area during each data forwarding includes the number of times the current data is forwarded, the waiting time for the previous data collector to forward the data, and the receiving time of the previous data collector to receive the data. When the data collector receives the current data, it calculates the set waiting time required by the current data collector by comparing the local receiving time with the waiting time for the previous data collector to forward data recorded in the variable area and the receiving time of the previous data collector to receive the data.

6. A method for operating the distributed inverter anti-reverse current communication architecture as described in any one of claims 1-5, characterized in that, Includes the following steps: When one of the data acquisition units detects the reverse signal, the inverter signal is transmitted to all the data acquisition units within one data transmission cycle through a unidirectional closed-loop communication topology. All data acquisition units synchronously send a power reduction signal for backflow prevention control to all inverters at the selected time base.

7. The working method of the distributed inverter anti-reverse current communication architecture as described in claim 6, characterized in that, Based on the data transmission cycle of the reverse signal transmission, the start time of the next data transmission cycle is taken as the selected time base. Alternatively, the time delay of the loopback time of the data acquisition device that identifies the inverter signal can be fixed as the selected time reference.

8. The working method of the distributed inverter anti-reverse current communication architecture as described in claim 6, characterized in that, When performing anti-reverse flow control, each data acquisition unit calculates the anti-reverse flow load reduction power required for the inverter it is responsible for based on the global power data within the data transmission cycle and the local power generation ratio. Then, the calculated anti-reverse flow load reduction power is evenly distributed to each inverter it is responsible for to obtain the required power reduction signal.

Images