Flexible direct current converter valve submodule optical fiber networking method and flexible direct current converter valve submodule communication system

Abstract

The invention relates to a flexible direct-current converter valve sub-module optical fiber networking method and a flexible direct-current converter valve sub-module communication system, and belongs to the technical field of converter valve control. On the basis of an existing flexible direct-current converter valve sub-module optical fiber networking method, communication between networking units is added, the adjacent networking units are connected through at least one receiving optical fiber and one transmitting optical fiber, and when uplink communication or downlink communication of the networking units fails, communication is conducted through the adjacent networking units and a power module interface case. According to the networking method, the two adjacent networking units communicate with each other, so that even if uplink communication or downlink communication of one networking unit fails, the adjacent networking units can communicate with the power module interface case, the communication redundancy is further improved, and the communication reliability is ensured.

Description

Technical Field

[0001] This invention relates to a fiber optic networking method for flexible DC converter valve submodules and a communication system for flexible DC converter valve submodules, belonging to the field of converter valve control technology. Background Technology

[0002] With the large-scale integration of new energy sources, the economy, stability, and security of power systems face enormous challenges. Flexible DC transmission technology has technological advantages in AC system interconnection, large-scale new energy grid connection, isolated power supply, and urban distribution network capacity expansion and upgrading, and is currently a leading technology in the power transmission and distribution field. Flexible transmission technology is a transmission technology based on voltage source converters (VSCs). It is a new type of DC transmission method following AC transmission and conventional DC transmission, and it has advantages such as flexible control, stable operation, and low losses.

[0003] Modular multilevel converters (MMCs) are core equipment for flexible DC transmission. The emergence of MMC technology has greatly promoted the development of flexible DC transmission technology. Currently, operational MMC projects have reached the 1000 MVA / ±320 kV level, and 3000 MVA / ±500 kV and 5000 MVA / ±800 kV MMC-HVDC projects are under construction. However, with the continuous increase in the number of levels, the number of bridge arm power modules also increases, leading to a large number of fiber optic connections between the power module interface chassis and the converter valve system. This results in high engineering costs and implementation difficulties, urgently requiring a low-cost solution. To address this, researchers have proposed a fiber optic networking method for modular multilevel converter power modules to reduce the number of fibers, thereby reducing the overall cost of the converter valve system. For example, Chinese patent application CN117118246A discloses a networking scheme and multi-redundancy communication method for power modules in a flexible DC converter valve. The scheme determines a target power module group based on the data reception delay of the power modules. n power modules in the same group communicate with two power module interface devices through equally spaced modules. The n power modules in the same group network with nearby power modules via their own high-speed communication optical modules and fiber optic patch cords, forming a ring-shaped network topology. The power module interface devices and power modules form a multi-redundancy communication architecture. In this architecture, each power module interface device groups its connected modules and then communicates with nearby power modules via its own high-speed optical module. This scheme reduces the number of long-distance optical fibers and improves communication redundancy to some extent. However, if communication with the power module interface devices in the same group is abnormal, all power modules in that group will be unable to communicate, indicating insufficient communication redundancy. Summary of the Invention

[0004] The purpose of this invention is to provide a fiber optic networking method and a communication system for flexible DC converter valve submodules, so as to solve the problem of low communication reliability caused by insufficient communication redundancy in the current fiber optic networking method for flexible DC converter valve submodules.

[0005] To solve the above-mentioned technical problems, this invention provides a method for fiber optic networking of flexible DC converter valve submodules, which includes the following steps: The power modules connected to the power module interface chassis are grouped. Each group of power modules is connected in a ring through a communication optical module to form a networking unit. Each networking unit communicates with the power module interface chassis through at least one transmit and one receive optical fiber. Adjacent networking units are connected by at least one transmit and one receive fiber optic cable. When either the uplink or downlink communication of a networking unit fails, communication is established between the adjacent networking unit and the power module interface chassis.

[0006] Furthermore, the power module interface chassis is redundantly configured, including two redundant power module interface chassis, and each networking unit communicates with the two redundant power module interface chassis.

[0007] Furthermore, the power modules within each networking unit communicate with the power module interface chassis at equal intervals via corresponding transceiver optical fibers.

[0008] Furthermore, when grouping the power modules connected to the converter valve power module interface chassis, the power modules in each group must meet the following requirements: the synchronization of command responses of all power modules in the group must be less than a certain value, and all power modules must be able to perform uplink time-division multiplexing without blocking.

[0009] Furthermore, the power module interface chassis is used to distribute the command information of all power modules in the networking unit to all power modules in the group. All power modules in the networking unit decode the data of the fastest channel according to the fastest path principle.

[0010] Furthermore, the power modules within each network unit synchronize according to the downlink frame completion flag of the fastest path, and generate uplink transmission enable signals according to the power module number. The interval between enabling signals ensures that the power module information can be transmitted, ensuring that uplink communication is serial and unblocked.

[0011] Furthermore, each power module within the networking unit has at least three pairs of transceiver fibers. Each optical receiving module in the power module can receive command information, and each optical transmitting module forwards the command after the synchronization time, and then sends status information.

[0012] Furthermore, the power modules within the networking unit communicate with the power module chassis according to power modules 1, [n / 3], [n / 2], [2n / 3], and n respectively. Specifically, power modules 1 and [n / 3] communicate with interface chassis 1, power modules [2n / 3] and n communicate with interface chassis 2, and power module [n / 2] communicates with the adjacent networking unit.

[0013] Furthermore, the frame format used by the command information received by the power module includes a frame header, command, and checksum. The command is arranged in a certain order. After each power module receives the command signal, it decodes it. After the checksum is passed, the corresponding command information is used according to its own position. Each power module forwards the command directly without delay after receiving it.

[0014] This invention also provides a flexible DC converter valve submodule communication system, including a power module interface chassis and a power module. The power module is used to connect to the power module interface chassis. The flexible DC converter valve submodule fiber optic networking method used in this communication system includes: The power modules connected to the power module interface chassis are grouped. Each group of power modules is connected in a ring through a communication optical module to form a networking unit. Each networking unit communicates with the power module interface chassis through at least one transmit and one receive optical fiber. Adjacent networking units are connected by at least one transmit and one receive fiber optic cable. When either the uplink or downlink communication of a networking unit fails, communication is established between the adjacent networking unit and the power module interface chassis.

[0015] Furthermore, the power module interface chassis is redundantly configured, including two redundant power module interface chassis, and each networking unit communicates with the two redundant power module interface chassis.

[0016] Furthermore, the power modules within each networking unit communicate with the power module interface chassis at equal intervals via corresponding transceiver optical fibers.

[0017] Furthermore, when grouping the power modules connected to the converter valve power module interface chassis, the power modules in each group must meet the following requirements: the synchronization of command responses of all power modules in the group must be less than a certain value, and all power modules must be able to perform uplink time-division multiplexing without blocking.

[0018] Furthermore, the power module interface chassis is used to distribute the command information of all power modules in the networking unit to all power modules in the group. All power modules in the networking unit decode the data of the fastest channel according to the fastest path principle.

[0019] Furthermore, the power modules within each network unit synchronize according to the downlink frame completion flag of the fastest path, and generate uplink transmission enable signals according to the power module number. The interval between enabling signals ensures that the power module information can be transmitted, ensuring that uplink communication is serial and unblocked.

[0020] Furthermore, each power module within the networking unit has at least three pairs of transceiver fibers. Each optical receiving module in the power module can receive command information, and each optical transmitting module forwards the command after the synchronization time, and then sends status information.

[0021] Furthermore, the power modules within the networking unit communicate with the power module chassis according to power modules 1, [n / 3], [n / 2], [2n / 3], and n respectively. Specifically, power modules 1 and [n / 3] communicate with interface chassis 1, power modules [2n / 3] and n communicate with interface chassis 2, and power module [n / 2] communicates with the adjacent networking unit.

[0022] Furthermore, the frame format used by the command information received by the power module includes a frame header, command, and checksum. The command is arranged in a certain order. After each power module receives the command signal, it decodes it. After the checksum is passed, the corresponding command information is used according to its own position. Each power module forwards the command directly without delay after receiving it.

[0023] The beneficial effects of this invention are as follows: Based on the existing fiber optic networking method for flexible DC converter valve submodules, this invention adds communication between networking units. Adjacent networking units are connected via at least one transmit and one receive fiber optic cable. In the event of a failure in either uplink or downlink communication of a networking unit, communication can be maintained between the adjacent networking unit and the power module interface chassis. This networking method ensures communication between adjacent networking units, further improving communication redundancy and guaranteeing communication reliability, even if the uplink or downlink communication of one networking unit fails. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the fiber optic network topology of the flexible DC converter valve submodule used in the embodiments of the present invention; Figure 2 This is a schematic diagram of the downlink communication data frame format used in the embodiments of the present invention; Figure 3 This is a schematic diagram of the uplink communication data frame format used in the embodiments of the present invention; Figure 4 This is a schematic diagram of the control logic for data selection during downlink communication used in the embodiments of the present invention; Figure 5This is a schematic diagram of the control logic for data selection during uplink communication used in the embodiments of the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] Based on the existing fiber optic networking method for flexible DC converter valve submodules, this invention adds communication between networking units, enabling communication between adjacent networking units. This means that even if the uplink or downlink communication of one networking unit fails, communication can still be maintained with the power module interface chassis through adjacent networking units, further improving communication redundancy and ensuring communication reliability.

[0027] Implementation Method of Fiber Optic Networking for Flexible DC Converter Valve Submodules This invention adds redundant communication between networking units, enabling communication between adjacent networking units. This allows a networking unit to communicate not only with the power interface chassis via its own communication link, but also with the power interface chassis via the communication link between adjacent networking units and the power interface chassis. Thus, even if the uplink or downlink communication of one networking unit fails, communication with the power module interface chassis can still be maintained through adjacent networking units, further improving communication redundancy and ensuring communication reliability.

[0028] Specifically, such as Figure 1 As shown, the converter valve system described in this embodiment includes an upper-level controller, a power module interface chassis, and power modules. The power module interface chassis are redundantly configured, including power module interface chassis 1 and power module interface chassis 2. Each power module chassis contains p interface units and two system MC boards, designated as system A and system B MC boards. The system A and system B MC boards of the power module chassis are two redundant control boards, both connected to the upper-level controller. Each power module interface chassis can connect to 1 to n (n≥144) power modules. The number of redundant power module interface chassis can be set according to actual needs, typically 2-3.

[0029] The multiple power modules of the converter valve system are divided into multiple groups, with the grouping principle being q / m=n, where q is the maximum number of interfaces that can be connected to a single power module chassis, m is the number of groups, and n is the number of modules in each group. The grouping requirement is to ensure that the synchronization of command responses from all power modules within a group is less than a certain value, and that the uplink time-division multiplexing of power modules is block-free. For example... Figure 1As shown, this implementation is divided into two groups, each with n power modules. Each power module in each group connects with the nearest power module via high-speed communication optical modules and fiber optic patch cords to form a local ring network, creating a network unit. Each network unit communicates with the power module chassis interface unit via at least one transmit and one receive fiber optic cable to ensure that the valve control and power module can perform normal control and monitoring functions. Each power module interface unit completes network communication via at least three transmit and three receive fiber optic patch cords. Adjacent network units are connected via at least one transmit and one receive fiber optic cable to ensure that the valve control and power module can still perform normal control and monitoring functions even if the uplink or downlink communication of the current network unit fails. Thus, when both uplink and downlink communication of a network unit fails, communication occurs between the adjacent network unit and the power module interface chassis; under other operating conditions, each network unit communicates directly with the power module interface chassis.

[0030] In principle, the grouping should ensure that the downlink communication synchronization time is less than 1µs, while ensuring sufficient idle time for uplink data transmission. For example, with a control cycle of 50µs and a single module information upload time of 1µs, it is important to note that when both uplink and downlink communication of a network unit fails, communication with the power module needs to be through an adjacent network unit. In this case, the adjacent network unit processes the power module data of two network units. Therefore, the number of power modules in a single network unit, n, is less than (50-t) / 2, where t is the time for forwarding instructions from two network units, thus determining the number of modules n.

[0031] Each networking unit communicates with two redundant power module interface chassis. Specifically, each networking unit communicates with the interface units in the redundant power module interface chassis through equally spaced power modules. For example, the intervals can be 1 / 5n, 1 / 4n, or 1 / 3n, where n is the total number of power modules in each networking unit. The specific number of intervals is set according to the actual situation, as long as the power modules in each group meet the requirements that the synchronization of command responses of all power modules in the group is less than a certain value and that the uplink time-division multiplexing of all power modules is unblocked.

[0032] The transmitting fiber from the power module interface chassis to the power module contains command information from all power modules within the network unit, arranged according to a specific protocol. The power modules decode this information according to the protocol. The receiving fiber from the power module to the power module interface chassis contains voltage and status information from all power modules within the network unit, also arranged according to a specific protocol. The power module interface unit decodes this information according to the protocol, thereby completing the control and monitoring of the power modules. The communication fiber from the power module interface chassis to the power modules is used to distribute command information from n power modules within the network to all power modules in the group. The power modules decode the data from the fastest path according to the fastest path principle. All power modules in the group execute the corresponding commands simultaneously after decoding, ensuring trigger synchronization. It should be noted that when all downlink communications of the network unit fail, the upper-level controller needs to send commands to the failed network unit through adjacent network units. Therefore, the number of power module command messages in adjacent network units is 2^n in this case.

[0033] Within each group, the power modules synchronize according to the downlink frame completion flag of the fastest path. Then, an uplink transmission enable signal is generated according to the power module number. The interval between enabling signals ensures that the power module information can be transmitted and that uplink communication is serial and unblocked. It should be noted that when the uplink communication of all network units fails, the failed network unit needs to upload its status information to the power module interface chassis through the adjacent network unit. Therefore, the number of power module status information is 2^n, and sufficient transmission time needs to be reserved to ensure that the power module status information of the two network units can be successfully transmitted in a time-division manner.

[0034] When adjacent network units communicate, the transmitting optical fiber of the normal network unit contains the instruction information of all power modules in the faulty network unit; the receiving optical fiber of the normal network unit contains the voltage and status information of all power modules in the faulty network unit, thereby completing the control and monitoring of the power modules.

[0035] For this embodiment, as Figure 1 As shown, networking unit 1 (i.e. Figure 1Module 1 can communicate with the power module interface chassis via modules 1, [n / 3] ([]: round down), [n / 2], [2n / 3], and n. The valve-controlled power module interface chassis is configured with dual redundancy, with the two chassis being redundant to each other. Module 1 communicates with board 1 of power module interface chassis 1, module [n / 3] communicates with board [p / 2]+1 of power module interface chassis 1, module [2n / 3] communicates with board 1 of power module interface chassis 2, and module n communicates with board [p / 2]+1 of power module interface chassis 2. Boards 1 and [p / 2]+1 of power module interface 1 are redundant to each other, as are board 1 and [p / 2]+1 of power module interface 2. The power module of one networking unit is connected to the interface chassis of two power modules via a 4-receive-4-transmit long optical fiber, and two adjacent networking units are connected via a 1-receive-1-transmit long optical fiber.

[0036] like Figure 2 As shown, when the downlink communication of a network unit is normal, it only needs to send instructions to its own power module. The downlink communication frame from the power module interface chassis to the power module includes a frame header, instructions, and checksums. The instructions are arranged in order from 1 to n, representing the instructions of the n modules. The checksum is performed using a CRC check polynomial. After receiving the frame data, the power module decodes it according to this protocol. Once the frame header and checksum are correct, the position information of power modules 1 to n is pre-set via local DIP switches or local flash memory. The power module extracts its own instructions according to the position information, and all power modules in the group follow this procedure to ensure instruction synchronization. It should be noted that when the downlink communication of all network units fails, adjacent network units need to send instructions to themselves and the power modules of the current network unit, with a total of 2^n instructions.

[0037] The commands issued by the power module interface chassis are from the same main control board, and then other interface units simply forward them without delay, ensuring consistency across all five downlink command channels. For example... Figure 3 As shown, the communication protocol between the power module and the power module interface chassis includes a frame header, module number, module status, and verification information. Each power module synchronizes according to the downlink communication frames. After synchronization, it generates a transmit enable based on its own position. The transmit enable interval ensures that uplink data is not blocked. It should be noted that when the uplink communication of all network units fails, adjacent network units need to upload the status of themselves and the current network unit's power modules, with a quantity of 2^n.

[0038] By using the above networking method, this implementation allows n power modules to be connected to the valve control via 5 transmit and 5 receive optical fibers, eliminating the need to set up transmit and receive optical fibers for each power module to connect to the valve control, thus simplifying the connection method and greatly reducing the connection cost.

[0039] Implementation of Communication System for Flexible DC Converter Valve Submodule The flexible DC converter valve submodule communication system of the present invention includes a power module interface chassis and a power module. The power module is used to connect to the power module interface chassis. The flexible DC converter valve submodule fiber optic networking method adopted by the communication system includes: 1) The power modules connected to the converter valve power module interface chassis are grouped: the grouping requirements are that the synchronization of the command response of all power modules in the group is less than a certain value, and the uplink time-division multiplexing of the power modules is unblocked; 2) Two redundant power module interface chassis and at least two equally spaced power modules complete uplink and downlink communication; the two power module interface chassis are redundant to each other, the downlink commands are consistent, and the uplink communication frame data is consistent; 3) Adjacent network units communicate with each other through at least one transmit and one receive fiber optic cable; the two network units are redundant with each other. If the uplink or downlink communication of the current network unit fails, it can communicate with the power module interface chassis through the adjacent network unit. 4) Each power module completes fiber optic network communication through its own optical module. Each power module has at least 3 pairs of transceiver fibers. Each optical receiving module can receive command information. Each optical transmitting module forwards the command after the synchronization time and then sends the status information.

[0040] The control logic for downlink communication in this embodiment is as follows: Figure 4 As shown, if any one of the downlink communication channels 1, 2, 3, and 4 from the power module interface chassis to the power module is normal, the downlink communication of the power module can still operate normally. The power modules achieve triple redundancy communication through 3 pairs of optical modules, and the 3 receiving optical modules follow the first-to-decode, first-to-use principle. If all of the downlink communication channels 1, 2, 3, and 4 from the power module interface chassis to the power module are abnormal, downlink communication will be conducted through adjacent network units. If the downlink communication between adjacent network units is normal, the downlink communication of the power module can still operate normally. If all of the downlink communication channels 1, 2, 3, and 4 from the power module interface chassis to the power module are abnormal, and the downlink communication between adjacent network units is also abnormal, the power module will not update its data, and the redundancy of n modules in that network unit will be lost. If all 3 receiving optical fibers of each power module are abnormal, the redundancy of that power module will be lost. The control logic for uplink communication in this embodiment is as follows: Figure 5As shown, if the uplink communication between the power module and the power module interface chassis via fiber optic cables 1, 2, 3, and 4 is normal, the power module interface chassis will use the first decoded cable as the first one used to monitor the power module status. If all four uplink communication cables between the power module interface chassis and the power module are abnormal, uplink communication will be attempted through adjacent network units. If uplink communication between adjacent network units is normal, the power module's uplink communication will still function normally. If all four uplink communication cables between the power module interface chassis and the power module are abnormal, and uplink communication between adjacent network units is also abnormal, the power module interface chassis will not update the information of n power modules, resulting in the loss of redundancy for those n modules in that network unit. If all three transmitting fiber optic cables of the power module fail, the redundancy of that power module will be lost.

[0041] Therefore, the communication system of this invention completes a ring network through high-speed communication optical modules and nearby power modules. Communication with the power module interface chassis is achieved through equally spaced power modules. Simultaneously, communication with adjacent network units is achieved through a 1-receive, 1-transmit optical fiber. This simplifies the communication between the n power modules and valve control optical fibers within the network from multiple receive / transmit to 5 receive / 5 transmit. This allows the converter valve control and power modules to complete power module control and monitoring through fewer optical fibers, saving costs and reducing deployment difficulty while ensuring control synchronization. Downlink communication merges and sends commands from the n modules, with each power module executing commands uniformly after decoding, ensuring command synchronization. Uplink communication uses time-division multiplexing to ensure uncongested uplink communication. The power module interface chassis of this invention has two layers of redundancy, each network unit has five layers of redundancy, and each power module has three layers of redundancy. This significantly increases communication redundancy and improves control reliability while reducing the number of long-distance optical fibers.

[0042] The flexible DC converter valve submodule communication system of the present invention can communicate with the power module interface chassis through four optical fibers when the communication between the networking unit and the power module interface chassis is normal. When the uplink or downlink communication of the networking unit fails, it can communicate with the power module interface chassis through the adjacent networking unit. There are a total of 5 redundancies, which greatly increases the communication redundancy while reducing the number of long-distance optical fibers and improving the control reliability.

Claims

1. A method of fiber networking for a flexible HVDC converter valve sub-module, the method comprising: providing a plurality of optical fibers; providing a plurality of optical fiber connectors; and connecting the plurality of optical fibers to the plurality of optical fiber connectors. The method includes the following steps: The power modules connected to the power module interface chassis are grouped. Each group of power modules is connected in a ring through a communication optical module to form a networking unit. Each networking unit communicates with the power module interface chassis through at least one transmit and one receive optical fiber. Adjacent networking units are connected by at least one transmit and one receive fiber optic cable. When either the uplink or downlink communication of a networking unit fails, communication is established between the adjacent networking unit and the power module interface chassis.

2. The fiber optic networking method for flexible DC converter valve submodules according to claim 1, characterized in that, The power module interface chassis is redundantly configured, consisting of two redundant power module interface chassis. Each networking unit communicates with both redundant power module interface chassis.

3. The fiber optic networking method for flexible DC converter valve submodules according to claim 2, characterized in that, The power modules within each networking unit communicate with the power module interface chassis at equal intervals via corresponding transceiver optical fibers.

4. The fiber optic networking method for flexible DC converter valve submodules according to claim 1, characterized in that, When grouping the power modules connected to the converter valve power module interface chassis, the power modules in each group must meet the following requirements: the synchronization of command responses of all power modules in the group is less than a certain value, and all power modules can use uplink time-division multiplexing without blocking.

5. The fiber optic networking method for flexible DC converter valve submodules according to claim 1, characterized in that, The power module interface chassis is used to distribute command information from all power modules in the networking unit to all power modules in the group. All power modules in the networking unit decode the data of the fastest channel according to the fastest path principle.

6. The fiber optic networking method for flexible DC converter valve submodules according to claim 3, characterized in that, The power modules in each network unit synchronize according to the downlink frame completion flag of the fastest path, and generate uplink transmission enable signals according to the power module number. The interval between enabling signals ensures that the power module information can be transmitted, and ensures that the uplink communication is serial and unblocked.

7. The fiber optic networking method for flexible DC converter valve submodules according to claim 1, characterized in that, Each power module in the network unit has at least 3 pairs of transceiver fibers. Each optical receiving module in the power module can receive command information. Each optical transmitting module forwards the command after the synchronization time and then sends the status information.

8. The fiber optic networking method for flexible DC converter valve submodules according to claim 3, characterized in that, The power modules within the network unit communicate with the power module chassis according to power modules 1, [n / 3], [n / 2], [2n / 3], and n respectively. Specifically, power modules 1 and [n / 3] communicate with interface chassis 1, power modules [2n / 3] and n communicate with interface chassis 2, and power module [n / 2] communicates with the adjacent network unit.

9. The fiber optic networking method for flexible DC converter valve submodules according to claim 5, characterized in that, The command information received by the power module adopts a frame format including a frame header, command, and checksum. The command is arranged in a certain order. After each power module receives the command signal, it decodes it. After the checksum is passed, it uses the corresponding command information according to its own position. Each power module forwards the command directly without delay after receiving it.

10. A flexible DC converter valve submodule communication system, comprising a power module interface chassis and a power module, wherein the power module is used to connect to the power module interface chassis, characterized in that, The communication system adopts the fiber optic networking method of the flexible DC converter valve submodule as described in any one of claims 1-9.

Images