A DC stability control system for an incomplete polar series commutation station

Abstract

The application discloses a DC safety and stability control system of an incomplete pole series converter station, and is applied to a series multi-terminal DC system. The series multi-terminal DC system comprises a high-end incomplete pole converter station, a low-end incomplete pole converter station and a stability control strategy master station. The high-end incomplete pole converter station is provided with a first safety and stability interface machine, a second safety and stability interface machine and a first pole control master machine. The low-end incomplete pole converter station is provided with a third safety and stability interface machine, a fourth safety and stability interface machine and a second pole control master machine. The first safety and stability interface machine and the third safety and stability interface machine are connected with the stability control strategy master station respectively. The first safety and stability interface machine and the second safety and stability interface machine are cross-connected with the first pole control master machine. The third safety and stability interface machine and the fourth safety and stability interface machine are cross-connected with the second pole control master machine. The DC safety and stability control system improves the stability of the series multi-terminal DC system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage direct current transmission, in particular to a DC security and stability control system of an incomplete pole series converter station. BACKGROUND

[0002] With the development of large-scale clean energy and the increasing demand for long-distance power transmission, series multi-terminal UHVDC transmission technology is widely used in cross-regional power interconnection due to its flexible networking and large capacity transmission capability. In the series multi-terminal DC system, the sending end or the receiving end is composed of multiple incomplete pole converter stations, that is, the high-end and low-end converters of the same pole are arranged in two physically independent converter stations, forming a high-end incomplete pole converter station and a low-end incomplete pole converter station. In the series multi-terminal DC system, the DC control and protection system needs to collect the converter operation data of the two incomplete pole converter stations and summarize the data as the overall DC operation data for the security and stability control system to calculate the power loss.

[0003] However, the existing method lacks a cross-station data integration mechanism for incomplete pole converter stations, and only a single inter-station communication link is configured. When the inter-station communication link is interrupted due to failure or network congestion, the stability control device of any end converter station cannot obtain the real-time state of the opposite end converter, thereby causing the security and stability control system to lack key data when calculating the power loss, which leads to a decrease in the stability margin of the series multi-terminal DC system and the AC power grid. SUMMARY

[0004] The present application provides a DC security and stability control system of an incomplete pole series converter station to solve the technical problem of how to improve the existing DC security and stability control system of an incomplete pole series converter station, and realize safe and stable control of the series multi-terminal DC system under complex conditions.

[0005] To solve the above technical problems, the present application provides a DC security and stability control system of an incomplete pole series converter station, which is applied to a series multi-terminal DC system, the series multi-terminal DC system comprising a high-end incomplete pole converter station, a low-end incomplete pole converter station and a stability control strategy master station, the high-end incomplete pole converter station being configured with a first security and stability interface machine, a second security and stability interface machine and a first pole control host, the low-end incomplete pole converter station being configured with a third security and stability interface machine, a fourth security and stability interface machine and a second pole control host;

[0006] The first security and stability interface machine and the third security and stability interface machine are connected with the stability control strategy master station respectively, the first security and stability interface machine and the second security and stability interface machine are cross-connected with the first pole control host, and the third security and stability interface machine and the fourth security and stability interface machine are cross-connected with the second pole control host;

[0007] The first stability interface machine of the high-end incomplete pole converter station is connected with the third stability interface machine of the low-end incomplete pole converter station through a stability control inter-station communication link, and the second stability interface machine of the high-end incomplete pole converter station is connected with the fourth stability interface machine of the low-end incomplete pole converter station through a stability control inter-station communication link; the first pole control host of the high-end incomplete pole converter station is connected with the second pole control host of the low-end incomplete pole converter station through a pole control inter-station communication link.

[0008] Preferably, in an embodiment of the present application, the first stability interface machine is configured to collect first alternating current operation data of the high-end incomplete pole converter station, and the third stability interface machine is configured to collect second alternating current operation data of the low-end incomplete pole converter station.

[0009] The second stability interface machine is configured to collect first direct current operation data of the high-end incomplete pole converter station and first control data of the first pole control host, and the fourth stability interface machine is configured to collect second direct current operation data of the low-end incomplete pole converter station and second control data of the second pole control host; the first control data includes a host station identification bit, direct current control mode data and converter operation state data.

[0010] Preferably, in an embodiment of the present application, the second stability interface machine and the fourth stability interface machine are further configured to:

[0011] acquire direct current operation data from a host station pole control host based on the host station identification bit;

[0012] When the host station identification bit indicates that the high-end incomplete pole converter station is the host station, the host station pole control host is the first pole control host of the high-end incomplete pole converter station; when the host station identification bit indicates that the low-end incomplete pole converter station is the host station, the host station pole control host is the second pole control host of the low-end incomplete pole converter station.

[0013] Preferably, in an embodiment of the present application, the first stability interface machine is further configured to perform preliminary fusion processing on the collected first alternating current operation data, the received first direct current operation data from the second stability interface machine and the first control data, to generate high-end station comprehensive data.

[0014] The third stability interface machine is further configured to perform preliminary fusion processing on the collected second alternating current operation data, the received second direct current operation data from the fourth stability interface machine and the second control data, to generate low-end station comprehensive data.

[0015] Preferably, in an embodiment of the present application, the high-end station comprehensive data or the low-end station comprehensive data each comprises real-time power loss amount and real-time power modulability;

[0016] The first stability interface machine and the third stability interface machine are further configured to:

[0017] analyzing the maximum deliverable power, the current actual delivered power and the converter operating state data of each converter in the comprehensive operation data to obtain the real-time power loss amount;

[0018] analyzing the adjustable power range of each converter under the current working condition in the comprehensive operation data to obtain the real-time power modulability.

[0019] Preferably, in an embodiment of the present application, the first stability interface machine is further configured to upload the high-end station comprehensive data to the stability control strategy master station; and the third stability interface machine is further configured to upload the low-end station comprehensive data to the stability control strategy master station.

[0020] The first stability interface machine and the third stability interface machine exchange the high-end station comprehensive data and the low-end station comprehensive data through a stability control station-to-station communication link.

[0021] Preferably, in an embodiment of the present application, the stability control strategy master station is configured to:

[0022] receive the high-end station comprehensive data and the low-end station comprehensive data, and analyze the high-end station comprehensive data and the low-end station comprehensive data to generate control instructions corresponding to the analysis results;

[0023] The control instructions include but are not limited to power adjustment instructions for the high-end incomplete pole converter station and the low-end incomplete pole converter station, converter control instructions and parameter adjustment instructions for the pole control master machine.

[0024] Preferably, in an embodiment of the present application, the stability control strategy master station is further configured to:

[0025] perform comparison processing on the high-end station comprehensive data and the low-end station comprehensive data, and if the comparison result shows that the data is consistent, the trend is normal and the correlation meets the expectation, generate comprehensive operation data of the series multi-terminal DC system;

[0026] Otherwise, match the result of the comparison processing with a pre-constructed fault database, and generate a stability control adjustment strategy according to the matching result.

[0027] Preferably, in an embodiment of the present application, the stability control strategy master station is further configured to send the control instructions to the first stability interface machine and the third stability interface machine.

[0028] The first stability interface machine is further configured to send control instructions related to the high-end incomplete pole converter station to the second stability interface machine and the first pole control host; and the third stability interface machine is further configured to send control instructions related to the low-end incomplete pole converter station to the fourth stability interface machine and the second pole control host.

[0029] Preferably, in an embodiment of the present application, the first stability interface machine and the third stability interface machine are further configured to:

[0030] When the inter-stability control station communication is normal, the DC operation data of the local pole control host and the opposite pole control host is directly obtained through the inter-stability control station communication link;

[0031] When the inter-stability control station communication is faulty, the DC operation data is obtained through the pole control host data of the opposite pole control host forwarded by the local pole control host by switching to the inter-pole control station communication link.

[0032] Compared with the prior art, the beneficial effects of the embodiment of the present application are as follows:

[0033] 1) By configuring the stability interface machine and the pole control host in the high-end / low-end incomplete pole converter station in a dual configuration and adopting a cross-connection mode, the system of the present application constructs a hardware redundancy and link fault-tolerant architecture. When the main device or a single link is faulty, the standby device or the redundant link can immediately take over the function, avoiding the interruption of information collection or the invalidation of control instructions caused by a single point failure, and significantly improving the reliability of device operation and the stability of data interaction under complex working conditions.

[0034] 2) The double standby communication channels formed by the inter-stability control station communication link and the inter-pole control station communication link realize the redundant backup of double-station information transmission. In normal times, real-time operation data and control instructions are efficiently transmitted according to the division of labor, and when a fault occurs, the channel is automatically switched to ensure that critical information is not lost, effectively solving the system instability problem that may be caused by traditional single-channel communication in the event of a link failure, providing double protection for the stable operation of the series multi-terminal DC system. Especially in cross-station data integration and abnormal working condition processing, through the complementary cooperation of the double links, the overall reliability and anti-interference ability of the system are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of a DC stability control system of an incomplete pole series converter station in an embodiment of the present application;

[0036] Figure 2 is a schematic diagram of an interface configuration of a DC stability control system of an incomplete pole series converter station provided by the present application;

[0037] REFERENCE NUMERALS:

[0038] Wherein, 11, stable control strategy host; 12, first stable interface machine; 13, second stable interface machine; 14, third stable interface machine; 15, fourth stable interface machine; 16, first pole control host; 17, second pole control host; 211, stable control strategy host A; 212, stable control strategy host B; 213, station 1 stable control interface machine A; 214, station 1 stable control interface machine B; 215, station 2 stable control interface machine A; 216, station 2 stable control interface machine B; 217, station 1 pole I pole control A; 218, station 1 pole I pole control B; 219, station 1 pole II pole control A; 220, station 1 pole II pole control B; 221, station 2 pole I pole control A; 222, station 2 pole I pole control B; 223, station 2 pole II pole control A; 224, station 2 pole II pole control B. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0040] In the description of the present application, the terms "first", "second", "third" and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third" and the like can explicitly or implicitly include or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0041] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication between two elements. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are only for illustrative purposes, and cannot be understood as indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. The term "and / or" used herein includes any and all combinations of the related listed items. 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.

[0042] In the description of the present application, it is necessary to explain that, unless otherwise defined, all the technical and scientific terms used in the present application are the same as the meanings commonly understood by the persons skilled in the art. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The above terms can be understood in the specific meaning in the present application by the persons skilled in the art.

[0043] An embodiment of the present application provides a DC security and stability control system of an incomplete pole series converter station, specifically, please refer to Figure 1 , Figure 1 The figure shows a schematic diagram of the DC security and stability control system of the incomplete pole series converter station in one embodiment of the present application. The system is applied to a series multi-terminal DC system, which comprises a high-end incomplete pole converter station, a low-end incomplete pole converter station and a stability control strategy master station 11. The high-end incomplete pole converter station is configured with a first security and stability interface machine 12, a second security and stability interface machine 13 and a first pole control master machine 16. The low-end incomplete pole converter station is configured with a third security and stability interface machine 14, a fourth security and stability interface machine 15 and a second pole control master machine 17.

[0044] The first security and stability interface machine and the third security and stability interface machine are connected with the stability control strategy master station respectively. The first security and stability interface machine and the second security and stability interface machine are cross-connected with the first pole control master machine. The third security and stability interface machine and the fourth security and stability interface machine are cross-connected with the second pole control master machine.

[0045] The first security and stability interface machine of the high-end incomplete pole converter station is connected with the third security and stability interface machine of the low-end incomplete pole converter station through a stability control inter-station communication link. The second security and stability interface machine of the high-end incomplete pole converter station is connected with the fourth security and stability interface machine of the low-end incomplete pole converter station through a stability control inter-station communication link. The first pole control master machine of the high-end incomplete pole converter station is connected with the second pole control master machine of the low-end incomplete pole converter station through a pole control inter-station communication link.

[0046] Among them, the high-end incomplete pole converter station and the low-end incomplete pole converter station respectively refer to the high-end and low-end converter stations in the series multi-terminal DC system, which are respectively at high and low voltage levels. The incomplete pole high and low end converter station indicates that it adopts a single pole configuration (only one pole device is configured, which is different from the double pole complete configuration). They are connected to the system through a series mode and are respectively configured with double security and stability interface machines (first / second security and stability interface machines, third / fourth security and stability interface machines) and pole control master machines (first / second pole control master machines), which undertake the tasks of power conversion and control in the DC system at different voltage levels.

[0047] The stability control strategy master station is a core control center of the system, which is connected with the first and third stability interface machines in the two end converter stations, receives and processes the high-end station comprehensive data and the low-end station comprehensive data, generates and issues power regulation, converter control and other instructions, and realizes the stability control and strategy coordination of the entire series multi-terminal DC system.

[0048] The stability interface machine is a device in the converter station responsible for data acquisition, preliminary fusion and communication interaction (such as the first stability interface machine acquiring the high-end station AC data, and the second stability interface machine acquiring the DC and pole control data), and has the functions of communication with the stability control strategy master station, the pole control master machine and the same function interface machine in the opposite end; the pole control master machine is a pole-level control core device in the converter station (such as the first pole control master machine responsible for the high-end station pole control), and the dual configuration ensures the control function redundancy and reliability; the stability control station communication link and the pole control station communication link are two types of communication channels between the converter stations, the former is used for data interaction between the stability interface machines (such as the first and third, and the second and fourth stability interface machines), and the latter is used for communication between the pole control master machines, and the two form a double standby channel to ensure uninterrupted transmission of system information in case of failure.

[0049] It can be understood that the dual configuration of the stability interface machine (such as the first to fourth stability interface machine) and the pole control master machine ensures the device redundancy to improve the reliability; the cross connection (such as the connection of the first, the second stability interface machine and the first pole control master machine) realizes real-time acquisition of local data; the stability control station communication link and the pole control station communication link form a double standby channel to avoid information interruption caused by single communication failure.

[0050] Specifically, the application deploys two sets of stability interface machines (master and backup) and dual pole control master machines in the high-end / low-end converter stations respectively, the stability interface machine is connected with the stability control strategy master station on the AC side and cross-connected with the local pole control master machine on the DC side, ensuring that another set can seamlessly take over in case of failure of a single set of equipment.

[0051] The stability control interface machine (such as the first and third, and the second and fourth) is interconnected through a dedicated communication link, and the pole control master machine (such as the first and second) also communicates through an independent link, the two types of links are mutually reserved, and when the stability control station communication fails, the data is automatically switched to the pole control station link for transmission, and vice versa.

[0052] Preferably, in one embodiment of the application, the first stability interface machine is used to acquire the first AC operation data of the high-end incomplete pole converter station, and the third stability interface machine is used to acquire the second AC operation data of the low-end incomplete pole converter station.

[0053] The second stability interface machine is used for collecting first DC operation data of the high-end incomplete pole converter station and first control data of the first pole control host, and the fourth stability interface machine is used for collecting second DC operation data of the low-end incomplete pole converter station and second control data of the second pole control host; the first control data comprises a leading station identification bit, DC control mode data and converter operation state data.

[0054] It can be understood that the AC / DC operation data (such as AC voltage and current, DC power speed drop, leading station identification bit) are collected and fused, which can provide comprehensive input for the stability control strategy.

[0055] Specifically, the first / third stability interface machine collects the three-phase voltage and current of the converter transformer incoming line of the high-end / low-end station, calculates the real-time power, and checks with the DC control data to avoid errors of a single data source.

[0056] The second / fourth stability interface machine obtains the DC control mode, leading station identification bit and converter operation state (such as maximum deliverable power and shutdown signal) from the local pole control host, wherein the leading station identification bit defaults to the high-end as the leading station, and automatically switches to the low-end when the communication is interrupted or the high-end exits, and is used for data source selection (such as the DC overall information obtained from the leading station value host).

[0057] The first stability interface machine fuses the AC data of the high-end station with the DC / control data collected by the second interface machine to generate comprehensive data of the high-end station (containing power, control mode and converter state); the third interface machine generates comprehensive data of the low-end station in the same way, and ensures the correlation and integration of AC / DC information in the same station.

[0058] Preferably, in an embodiment of the present application, the second stability interface machine and the fourth stability interface machine are also used for:

[0059] obtaining the DC operation data from the leading station pole control host based on the leading station identification bit.

[0060] Preferably, in an embodiment of the present application, the first stability interface machine is also used for preliminarily fusing the collected first AC operation data with the received first DC operation data and first control data from the second stability interface machine to generate comprehensive data of the high-end station;

[0061] The third stability interface machine is also used for preliminarily fusing the collected second AC operation data with the received second DC operation data and second control data from the fourth stability interface machine to generate comprehensive data of the low-end station.

[0062] It can be understood that the comprehensive data is exchanged through the communication link between the stability control stations to realize information sharing of the high-end / low-end stations and provide a global perspective for the stability control strategy master station; ensure real-time synchronization of the data of the double stations and support calculation of key parameters such as power loss.

[0063] Preferably, in an embodiment of the present application, the high-end station comprehensive data / low-end station comprehensive data includes real-time power loss and real-time power modulability;

[0064] The first stability control interface machine and the third stability control interface machine are further used for:

[0065] The maximum deliverable power, the current actual delivered power and the converter operation state data of each converter in the comprehensive operation data are analyzed to obtain the real-time power loss;

[0066] The adjustable power range of each converter in the current working condition in the comprehensive operation data is analyzed to obtain the real-time power modulability.

[0067] The real-time power loss reflects the actual power transmission capacity reduction degree of the DC system caused by converter faults, maintenance or operation restrictions, and is a key basis for the stability control strategy master station to judge whether power transfer, load shedding or adjustment of other DC channel power needs to be started. By quantifying the power gap, the system power balance is ensured, and the frequency or voltage fluctuation of the alternating current system caused by power imbalance is avoided.

[0068] The real-time power modulability represents the power range that can be flexibly adjusted (including power boosting and power reduction capacity) of the DC system in the current working condition, provides a quantitative basis for the stability control strategy master station to generate power modulation instructions (such as emergency power boosting or emergency power reduction to maintain the frequency of the alternating current grid within a reasonable range), ensures that the instructions are executed within the converter capacity range, and avoids equipment damage or control failure.

[0069] Preferably, in an embodiment of the present application, the first stability control interface machine is further used for uploading the high-end station comprehensive data to the stability control strategy master station; and the third stability control interface machine is further used for uploading the low-end station comprehensive data to the stability control strategy master station.

[0070] The first stability control interface machine and the third stability control interface machine exchange high-end station comprehensive data and low-end station comprehensive data through a communication link between the stability control stations.

[0071] Specifically, the first / third stability control interface machine uploads the high-end / low-end station comprehensive data to the stability control strategy master station, and at the same time, directly exchanges the comprehensive data of each other through the communication link between the stability control stations (such as the high-end station comprehensive data is transmitted to the third interface machine, and the low-end station comprehensive data is transmitted to the first interface machine), forming double-station data sharing.

[0072] Under normal conditions, the stability control interface machine directly obtains the DC operation data of the opposite pole control host through the stability control inter-station link; if the stability control inter-station communication fails, the opposite data is forwarded by the local pole control host (such as the first pole control host receiving the second pole control host data and forwarding it to the first stability control interface machine), ensuring that the data is not lost.

[0073] Preferably, in an embodiment of the present application, the stability control strategy master station is used for:

[0074] receiving the high-end station comprehensive data and the low-end station comprehensive data, and analyzing the high-end station comprehensive data and the low-end station comprehensive data to generate control instructions corresponding to the analysis results;

[0075] The control instructions include but are not limited to power regulation instructions, converter control instructions for the high-end incomplete pole converter station and the low-end incomplete pole converter station, and parameter adjustment instructions for the pole control host.

[0076] It can be understood that based on the double-station comprehensive data, control instructions (such as power regulation and converter blocking) are generated to compare data consistency to identify abnormalities and ensure system stability; real-time power loss and modulatable amount are calculated to provide a basis for power adjustment.

[0077] Preferably, in an embodiment of the present application, the stability control strategy master station is further used for:

[0078] comparing and processing the high-end station comprehensive data and the low-end station comprehensive data, and if the comparison result shows that the data is consistent, the trend is normal, and the correlation meets the expectation, generating comprehensive operation data of the series multi-terminal DC system;

[0079] If the comparison result shows that the data is abnormal, a stability control adjustment strategy matching the data abnormal result is generated.

[0080] Specifically, after the master station receives the high-end / low-end station comprehensive data, it first compares the double-station data (such as power and converter state), and if they are consistent and the trend is normal, it generates comprehensive operation data containing real-time power loss (the difference between the maximum deliverable power of each converter and the actual power) and modulatable amount (the power regulation range of each converter under the current working condition); if the data is abnormal (such as power sudden drop and state conflict), a stability control adjustment strategy (such as power drop and island blocking) is triggered.

[0081] According to the comprehensive operation data, control instructions (such as increasing power and blocking specific converters) for the high-end / low-end station are generated, which are preferentially sent to the corresponding stability control interface machine (such as instructions involving the high-end station sent to the first interface machine and the low-end station sent to the third interface machine), and then forwarded by the interface machine to the local pole control host for execution, ensuring that the instructions accurately reach the target equipment.

[0082] Preferably, in an embodiment of the present application, the stability control strategy master station is further configured to send the control instructions to the first stability interface machine and the third stability interface machine.

[0083] The first stability interface machine is further configured to send the control instructions related to the high-end incomplete pole converter station to the second stability interface machine and the first pole control master machine; and the third stability interface machine is further configured to send the control instructions related to the low-end incomplete pole converter station to the fourth stability interface machine and the second pole control master machine.

[0084] After the master station generates the instructions, the instructions are sent to the corresponding stability interface machines (first / third interface machines) according to the target equipment classification (such as high-end station / low-end station, specific converter), and then the interface machines further distribute the instructions according to the instruction type: the instructions related to the local pole control master machine (such as power modulation) are directly sent to the dual pole control master machine, and the instructions related to the opposite equipment are forwarded through the inter-station link (such as the first interface machine transmits the low-end station related instructions to the third interface machine).

[0085] After the pole control master machine receives the instructions, the current dominant station standby machine prioritizes the execution of the instructions in combination with the dominant station identification bit and the on-duty machine state (such as the pole control master machine of the high-end station prioritizes the processing of global power regulation instructions when the high-end station is the dominant station), thereby ensuring the uniformity of the control logic.

[0086] Preferably, in an embodiment of the present application, the first stability interface machine and the third stability interface machine are further configured to:

[0087] When the stability control inter-station communication is normal, the direct current operation data of the local and opposite pole control master machines is directly obtained through the stability control inter-station communication link;

[0088] When the stability control inter-station communication fails, the direct current operation data is obtained through the opposite pole control master machine data forwarded by the local pole control master machine by switching to the pole control inter-station communication link.

[0089] It can be understood that, by means of equipment redundancy and logic switching, the present application ensures the continuous operation of the system when a single set of equipment fails or communication fails, thereby avoiding global failure caused by local failure.

[0090] Specifically, by configuring two sets of interface machines, only one set of equipment is withdrawn when a fault occurs, and the other set of equipment continues to operate, without affecting data acquisition and instruction forwarding; if both sets of equipment are withdrawn, the stability control strategy master station detects the communication interruption and directly sends instructions such as power reduction and DC lockout to the pole control master machine (through the pole control inter-station link or the backup channel), thereby maintaining the minimum safe state of the system.

[0091] When the communication between the stability control stations is normal, data is exchanged through the link in priority; if there is a fault, the inter-pole control station link is automatically enabled, and the data forwarding task is undertaken by the pole control host (for example, the pole control host of the low-end station transmits the converter information to the pole control host of the high-end station, and the latter provides the information to the stability interface machine of the high-end station), so as to ensure that the aggregation of the converter operation information is not interrupted, and the stability control function continuously calculates the power loss.

[0092] Another embodiment of the present application provides a configuration system of an incomplete-pole series-connected converter station and a stability interface. Figure 2 Figure 2 The configuration system of the DC stability control system of the incomplete-pole series-connected converter station provided by one of the embodiments of the present application.

[0093] Specifically, the stability interface machines (which can also be referred to as stability execution terminal machines) are configured in the high-end and low-end incomplete-pole converter stations respectively, and are configured in a dual manner. The stability interface machine is connected to the stability strategy master station on the AC system side, and is cross-connected with the pole control host of the incomplete-pole converter station on the DC side, and is correspondingly connected with the stability interface machine of another incomplete-pole converter station.

[0094] Through the configuration, the information synchronization and aggregation between the pole control hosts of the two incomplete-pole converter stations, and the information synchronization and aggregation of the stability interface machines of the two incomplete-pole converter stations are realized, so as to realize the real-time collection and transmission of the DC operation information sent by the DC control and protection to the stability interface machine, and the real-time collection and transmission of the instructions sent by the stability interface machine to the DC control and protection, so as to ultimately realize the information interaction of the DC control and protection and the stability of the series multi-terminal DC system.

[0095] The main interface functions of the stability interface machine include:

[0096] 1) Collecting AC information of the incomplete-pole converter station, including three-phase AC voltage and current of the converter transformer incoming line, etc., for calculating real-time power and checking with the DC control and protection information;

[0097] 2) Collecting information sent by the DC control, including DC power reduction amount and its identification bit, DC power modulatable amount and its identification bit, DC control mode, pole control host state, operation state of each converter, and normal shutdown signal of the converter;

[0098] 3) Sending DC operation information collected from the incomplete-pole converter station to another incomplete-pole converter station, and obtaining DC operation information collected from another incomplete-pole converter station;

[0099] 4) Aggregating the collected information, processing to obtain DC overall operation information, and sending the information to the stability strategy master station for executing the stability strategy. The most core part of the aggregation and processing is to consider the states of the two incomplete-pole converter stations, and to calculate real-time power loss amount and real-time power modulatable amount;

[0100] ​5) Receive the instruction of stability strategy master station, send the DC power modulation instruction, island locking instruction and so on to the DC pole control host of the incomplete pole converter station;

[0101] 6) Signal processing, data transmission and abnormality detection, AC / DC abnormal condition logical discrimination and processing, device abnormal state self-checking and alarm integrated for executing the above functions.

[0102] The pole control host has the following interface functions:

[0103] 1) DC overall operation information summary and sending: in each incomplete pole converter station, the pole control host obtains the DC overall information by station communication summary or only by the electrical information collected in the station according to the real-time operation state, and sends the DC overall information to the stability interface machine of the station, including the DC power speed reduction amount and its identification bit, the DC power modulatable amount and its identification bit, and the DC control mode.

[0104] 2) Station converter operation information summary: in each incomplete pole converter station, the pole control host can directly collect the DC operation information of the station, including the DC control mode, the converter operation information (the maximum deliverable power of the converter, the converter deliverable power instruction value, the non-normal shutdown signal, etc.), and sends the information to the stability interface machine of the station.

[0105] 3) Station-to-station converter operation information forwarding: when the DC control and protection station-to-station communication is normal, the pole control host collects the converter operation information of another incomplete pole converter station through station communication in addition to collecting the information of the station, and sends the information to the stability interface machine of the station.

[0106] 4) Pole control master station definition and identification: since the high and low end converters of each pole are arranged in two incomplete pole converter stations, the high and low ends are respectively configured with DC hosts, which both have the function of controlling the DC pole. The two stations have a certain master-slave relationship, and the pole control host in the station currently in the dominant control position is defined as the pole control master station. The pole control host sends the identification bit to the connected stability interface machine in real time, which is used for data source selection and judgment of the stability interface machine.

[0107] 5) Signal processing, data transmission and abnormality detection, AC / DC abnormal condition logical discrimination and processing, device abnormal state self-checking and alarm integrated for executing the above functions.

[0108] The station-to-station communication interface includes:

[0109] 1) A / B master-standby dual host of any pole control host of any incomplete pole converter station, which communicates with the pole control host of the same pole of another incomplete pole converter station, and the communication content includes DC overall information (including DC speed reduction signal, DC power boostable / DC power reducible signal, DC control mode) and information required for calculating DC voltage and current.

[0110] 2) Any stability interface machine of any incomplete pole converter station communicates with the corresponding stability interface machine of another incomplete pole converter station, and the interactive communication content includes the AC side information of the station and the information received from the pole control host of the station.

[0111] 3) The stability interface machines of the two incomplete pole converter stations both communicate with the upper stability strategy master station, and send the DC power loss calculated by the stability interface machine and receive stability strategy instruction information.

[0112] After adopting the above configuration and interface scheme, the specific method for the stability system to obtain information from the DC control and protection includes:

[0113] The overall DC information: the DC power drop signal is calculated by the pole control host of the "leading station, control pole", and then sent to the corresponding stability control interface machine. The stability control obtains this signal from the control pole leading station duty host. The DC power drop amount / identification bit, the DC power that can be increased / decreased / identification bit is also calculated by the pole control host, and the acquisition method is similar to the power drop signal. The DC control mode is set by the operation personnel in each pole, and the stability control obtains it from the duty host of each pole leading station, which is used to judge whether the power transmission can be carried out.

[0114] Pole control host state information: the DC pole control duty state is judged by each set of main and standby host of the pole control, and the stability control obtains this information from each host, and the stability control device only executes the command of the duty host.

[0115] Converter operation information: the maximum deliverable power of the converter is calculated by the four pole control hosts distributed in the two stations and two poles, and is forwarded between the stations. The stability control obtains this information from the duty host of the station and summarizes it. If the stability control inter-station communication fails, the information is obtained through the pole control forwarding. The acquisition method of the converter deliverable power instruction value, abnormal outage signal, operation state, and normal outage signal is similar to the maximum deliverable power.

[0116] Leading station information: the leading station identification bit is used to indicate whether the station is in the leading control position in the two incomplete pole converter stations for the pole. By default, the high end is the leading station, and the low end is the leading station when the inter-station communication is interrupted or the high end exits. The identification bit is sent by the pole control host to the connected stability interface machine in real time, and the stability control obtains this information from each host.

[0117] The specific method for the DC control and protection to obtain information from the stability system is as follows:

[0118] Locking instruction: When the stability strategy master station judges the system operation state, it sends locking instructions to each pole control master station according to the preset strategy, including locking the direct current and respectively locking the high-end and low-end converters of pole I and pole II. The pole control master station obtains these instructions from the control pole, master station and on-duty master station, and the pole control master station obtains the locking instructions of the converters from the corresponding master station.

[0119] Island signal: including direct current island signal, direct current high-end island signal and direct current low-end island signal, which respectively indicate that the system appears corresponding island state, and the pole control needs to delay lock the entire direct current, high-end converter station or low-end converter station. The pole control obtains the direct current island signal and direct current high-end island signal from the incomplete converter station 1 control pole on-duty master station, and obtains the direct current low-end island signal from the incomplete converter station 2 control pole on-duty master station.

[0120] Power modulation instruction: the boost direct current power signal / boost amount / identification bit and the drop direct current power signal / boost amount / identification bit are used to indicate that the direct current needs to boost or drop power. After the stability generates these instructions, the pole control obtains them from the control pole, master station and on-duty master station.

[0121] When the above configuration scheme is adopted, the processing mode of some typical and abnormal working conditions is as follows:

[0122] Stability control interface machine inter-station communication failure: at this time, the acquisition mode of the direct current overall information and the pole control master station on-duty state information is the same as that in the normal case. The acquisition of the converter operation information changes, the stability control interface machine cannot obtain the information of the other station through inter-station communication, and can only obtain it from the directly connected pole control master station. Meanwhile, the pole control master stations of the two incomplete pole converter stations mutually forward the related information, so as to ensure the normal operation of the stability control function.

[0123] Direct current control pole control master station inter-station communication failure: the acquisition mode of the direct current overall information, the pole control master station on-duty state and the converter operation information is consistent with that in the fault-free state. The converter operation information is transferred and summarized by the stability control interface machine through inter-station communication, so as to ensure the completeness of the information and enable the stability control system to normally calculate the power loss and execute the corresponding strategy.

[0124] Partial exit of the direct current control pole control master station: the pole control master station automatically switches the on-duty master station, master station and other states and updates the identification bit. In this case, the stability control obtains information in the same way as in the fault-free state, so as to ensure that the stability control function is not affected and the system can still operate stably.

[0125] Partial exit of the stability control interface machine: if only one set of the double-set running master station exits, it has no effect on the system operation; if both sets of the double-set running master station exit, the stability strategy master station will detect and send power drop, direct current locking and other instructions according to the system demand, so as to maintain the safe and stable operation of the system.

[0126] In order to further explain the effectiveness and feasibility of the present application, the present application is further illustrated by the following examples.

[0127] Example 1

[0128] In a series multi-terminal DC interconnected DC power transmission system, in order to realize efficient stability control function, the high and low end converter stations are respectively configured with stability control interface machines, and each stability control interface machine is cross-connected with the DC pole control host of the station. This design ensures that each converter station can collect and process real-time local DC operation information, providing a hardware basis for subsequent stability control functions.

[0129] Specifically, the pole I and pole II pole control hosts of each converter station are responsible for real-time monitoring of the operation state of the corresponding pole of the station, summarizing the bipolar information, and generating the following key information for sending to the stability control:

[0130] 1) DC pole control mode: indicating the control mode of the current system, affecting the power transfer behavior after fault and the power distribution of the two poles, used for power loss calculation of the stability control interface machine;

[0131] 2) Maximum deliverable power of the converter: representing the operating capacity of the converter, determined according to DC system parameters and limitations such as overload capacity, providing a basis for power loss calculation by the stability control interface machine;

[0132] 3) Converter power delivery instruction value: the target power value generated by the DC control system, which is the target value of the current DC power, used for power loss calculation by the stability control interface machine;

[0133] 4) Abnormal outage signal: indicating whether the converter is in an abnormal outage state, used for power loss calculation by the stability control interface machine;

[0134] 5) Power boost / speed down signal and identification bit: representing the power regulation capability and current state of the DC system, used as a basis for stability control to determine whether to issue power boost / speed down and instruction value.

[0135] After the above information is transmitted from the pole control hosts to the stability control interface machine of the station through the station communication channel, the stability control interface machine gradually analyzes and processes the received signals according to the preset processing procedure, ensuring the integrity of the signals, the clearness of the priority and the accuracy of the logical judgment, to meet the technical requirements of the stability control function.

[0136] The stable control interface machine first classifies the received data according to the type and purpose of the signal. High-priority signal data includes power speed reduction signal data, DC pole control mode data, and converter maximum deliverable power data, etc. These data directly affect the core operation of the stable control logic and are marked as key data, entering the priority processing channel for high-frequency real-time updating and rolling calculation. General priority signal data includes converter delivery power instruction value data, abnormal shutdown signal data, etc. After classification, these data enter the regular processing channel to ensure the completeness of the overall operation information of the system.

[0137] After signal classification, the stable control interface machine further checks the consistency of various signals and performs logic verification. For example, if both the main and standby pole control hosts are in or not in the on-duty mode, it is judged as an abnormal state. When an abnormal signal is detected, the stable control interface machine starts the preset fault handling logic to ensure that the signal abnormality does not have a major impact on the stable control function.

[0138] After classification and verification, the stable control interface machine temporarily stores the processed signals in the local cache module of the stable control interface machine and further integrates the inter-station communication data transmitted by the opposite end station. Based on the integrated data, the stable control interface machine completes the pre-generation of the stable control strategy and applies the strategy to the subsequent stable control logic judgment and instruction generation process. In the case of inter-station communication abnormality or device exit operation, the stable control interface station can independently complete the calculation and logic judgment of power loss, ensuring the continuity and stability of the stable control function.

[0139] Through the above signal analysis, classification, verification and processing process, the stable control interface station of the present application realizes accurate management and efficient utilization of the in-station DC information, provides reliable data support for inter-station communication and stable control instruction generation, and meets the efficiency and reliability requirements of the series multi-terminal UHV DC transmission project for incomplete pole series converter station pole control and connected stable control function.

[0140] During the operation of the stable control system, to realize the coordination between the high and low end converter stations, the stable control interface machine interacts with the opposite end stable control interface machine through the inter-station communication channel. The core purpose of inter-station communication is to collect the operation information of the high and low end converter stations to ensure that the stable control function can obtain complete system state data for accurate logic judgment and stable control instruction generation. To realize comprehensive collection of DC information and efficient execution of stable control logic, the stable control interface machines of the high and low end converter stations realize real-time interaction and integration of data through the inter-station communication channel, the whole process includes the following key links.

[0141] 1) Information transmission: Under normal operating conditions, the local stability control interface machine sends the information collected by the local DC control host (such as DC control mode, maximum power transmission of the converter, power drop signal, etc.) to the opposite end stability control interface machine through the inter-station communication channel. At the same time, the stability control interface machine receives the corresponding data from the opposite end. In order to ensure the accuracy of transmission, the information is packaged in frame structure, and a time stamp, a check bit and a priority identifier are attached in each frame of data, and a main channel and a backup channel are used, wherein the main channel is used for information transmission under normal operating conditions, supporting high bandwidth and low latency; the backup channel is used as a redundant design of the main channel, and is used for information supplement under abnormal communication or fault conditions. The interactive information includes key operating data (such as power drop signal, DC control mode, etc.) and auxiliary operating data (such as converter operating state, abnormal shutdown signal, etc.).

[0142] 2) Data synchronization: After receiving the information of the opposite end station, the stability control interface machine calibrates the local data and the opposite end data with time stamp to ensure the consistency of the data in the stability control logic judgment. First, compare the time stamps of the opposite end data and the local time stamps, and calculate the time delay difference between them. Then, align the data, and for the data packets with time difference, the stability control interface machine aligns them according to the preset time window to ensure the synchronization of the data of the two stations. Finally, handle the packet loss, and when the data packet loss or time stamp of the opposite end station is detected, the stability control interface machine will record the exception and trigger the backup logic for compensation.

[0143] 3) Abnormal handling and compensation: When the inter-station communication is abnormal or the received opposite end data is incomplete, the stability control interface machine will first compensate for the missing data. For missing key signals (such as power drop signal, maximum power transmission of the converter), the stability control interface machine compensates for them by logical derivation or based on local historical data. For example, if the power drop signal of the opposite end station is missing, the stability control interface machine will derive a reasonable alternative value based on the local power data and the drop logic. Then filter the abnormal signals. For data packets with incorrect identification bits or logical conflicts, the stability control interface machine will filter them and record them in the system log, and issue a fault warning at the same time.

[0144] 4) Data integration and analysis: After completing data synchronization and abnormal handling, the stability control interface machine integrates and analyzes the data of the local and opposite end stations. First, prioritize the key signals: high-priority signals (such as power drop signal, DC control mode) are prioritized for integration, which are used to guide the execution of the stability control logic in real time. Then, the data of the whole station is summarized: the stability control interface machine calculates the DC power loss based on the integrated data of the whole station, which includes: adding the maximum power transmission of the local and opposite end converters to obtain the total transmission capacity of the whole station; comparing the power instruction value of the whole station with the actual power transmission value to calculate the power loss; reporting the power loss to the stability control master station for subsequent stability control instruction generation.

[0145] 5) Special working condition processing: In the cross operation of two incomplete pole converter stations in DC system (for example, station 1 pole I converter operation + station 2 pole II converter operation, and other converters and corresponding pole control host computers are exited), three valve group operation and other complex working conditions, the logic of the stability control interface machine has been adjusted adaptively.

[0146] The preferred processing mode is that two stability control execution stations obtain DC control information received by the stability control information of the other station through stability control station communication, and perform stability control local summary, so as to obtain all DC information; if the above mode is not available due to communication interruption and other reasons, the stability control interface machine performs summary through pole control forwarding information, specifically, the pole control host station summarizes and transmits key DC operation data (such as power speed drop signal, identification bit, etc.), so that the stability control obtains all information.

[0147] In an extreme case, if the opposite data is not available, the stability control interface machine only uses local data to complete the power loss calculation independently, to ensure the continuity of system operation.

[0148] Through the above inter-station communication and signal interaction mechanism, the application can realize efficient transmission of DC information and integrity of stability control function under normal working conditions. This mechanism effectively solves the influence of stability control function caused by inter-station communication interruption or data loss due to the layout of incomplete pole converter stations in multi-terminal series ultra-high voltage DC system, and provides technical support for the stable operation of DC power transmission system.

[0149] In the application, in order to ensure the reliability of stability control function under complex working conditions, especially in the case of cross operation, communication anomaly or device exit operation, a pole control host station mechanism is introduced. There are four pole control host computers in the same pole (pole I or pole II) in two incomplete pole converter stations, only one station is the pole control host station at the same time, and only one pole control host computer is the pole control host station on duty. Especially responsible for generating and transmitting global key signals, including DC power speed drop signal, speed drop amount and identification bit, etc. At the same time, the stability control interface machine obtains the operation information of four converters through stability control inter-station forwarding or pole control inter-station forwarding. The stability control interface machine completes the calculation of power loss based on the above information.

[0150] After receiving the data of the host station and the non-host station, the stability control interface machine integrates all station data and calculates the power loss. First, the running power data is summarized, the maximum deliverable power and actual power delivery value of the converter are obtained from the local pole control host computer; the corresponding data is received from the opposite station (if the communication is normal); the host station is responsible for preferentially providing the power data of all stations, which is taken as the calculation basis by the stability control interface machine. Then, the power loss is calculated in real time according to the fault blocking signal, power back-off signal, etc.

[0151] In the present application, the stability control master station generates stability control strategy and issues execution instructions based on the power loss reported by each stability control interface and the overall station operation information, so as to realize real-time stability control of the DC power transmission system. The instructions include power increase, power decrease, blocking of the converter and DC island operation, etc.

[0152] 1) Data aggregation and strategy generation: After receiving the power loss data from the stability control interface and the aggregated overall station operation information, the stability control master station generates the stability control strategy through the following steps:

[0153] Power loss evaluation: The stability control master station evaluates the power gap of the overall station according to the power loss data reported by each stability control interface. When the power loss is found to exceed the set threshold, the stability control strategy generation logic is started according to the preset strategy determined by system research;

[0154] Operation state analysis: The DC pole control mode, the converter operation state and the abnormal shutdown signal of the overall station are checked. According to the operation state, the parameter configuration of the stability control strategy generation is adjusted to determine the stability control strategy that can be executed, such as dynamic adjustment of the power instruction, removal of the generator set, etc.

[0155] Strategy generation logic: The power instruction value of the converter is adjusted to increase or decrease the power transmission, so as to balance the power of the AC / DC system. When the operation state of the AC system faces risks and cannot continue to support power transmission, the power decrease or even blocking instruction is generated to block the risks in time. In the extreme case, when the AC system enters island operation, the stability control master station generates the island operation instruction according to the remaining operation data to block the DC in time.

[0156] 2) Instruction issuance and distribution: After generating the stability control strategy, the stability control master station distributes the instructions to each stability control interface through the communication channel. First, the instructions are classified and priority is assigned. The high-priority instructions (such as blocking of the converter and power decrease instruction) are directly sent to the target stability control interface through the real-time transmission channel; the general priority instructions (such as power increase / decrease instruction) are distributed in sequence through the regular channel. Then, the main channel and standby channel switching is implemented. When the main channel fails, the stability control master station automatically switches to the standby channel for instruction transmission to ensure the reliability of the instruction issuance. Finally, the instruction verification and confirmation are completed. After receiving the instructions, the stability control interface verifies the integrity and consistency of the instructions and sends a confirmation signal to the stability control master station to ensure the correct execution of the instructions.

[0157] 3) Command processing and execution of the stability control interface machine: After receiving the command issued by the stability control master station, the stability control interface machine first analyzes the command content and extracts the specific execution content (such as target power value, locking state identifier, etc.) from the command package. Then, the logic is judged and verified, and the rationality of the command is verified according to the local data and the current running state, for example: whether the power boost command exceeds the maximum deliverable power of the converter; whether the converter locking command is consistent with the actual abnormal shutdown signal. Finally, the command is executed, and the parsed command is sent to the pole control host, which completes the specific power adjustment, converter locking, etc.

[0158] 4) Command execution state feedback: After executing the command, the stability control interface machine feeds back the execution result and state to the stability control master station, including: command execution state and running state update, where the command execution state includes the completion state of power adjustment, converter locking state, etc.; the running state update includes the stability control interface machine sending the latest running data after execution to the stability control master station for subsequent adjustment of the stability control strategy.

[0159] Example 2

[0160] Scenario setting: In a series multi-terminal DC system, incomplete pole converter station 1 is a high-end converter station, and incomplete pole converter station 2 is a low-end converter station. Station 1 and station 2 each have two converters, pole I and pole II, and the four converters of the two stations are respectively configured with master and standby pole control hosts; station 1 and station 2 are respectively configured with stability control interface machines. When the stability control communication channel between station 1 and station 2 is interrupted, the stability control interface machines between station 1 and station 2 cannot directly interact data. At this time, the stability control will obtain information from the DC control and protection in the backup mode summarized by the DC control and protection.

[0161] Assume that at this time each pole control host is on duty, the B machine is standby, and both stations are controlled by pole I, and both levels are dominated by station 1; there is no master / standby relationship between the A and B machines of the stability control interface machine, and they are in parallel. The fault solving steps in this scenario are described as follows.

[0162] 1) Stability control interface machine judges stability control station communication fault: Taking station 1 stability control interface machine A as an example, under normal conditions, the machine should obtain all DC information through the two pole control hosts of station 1 pole I pole control A and station 1 pole II pole control A connected directly, but after the stability control station communication fault, the stability control interface machine A judges that the stability control station communication is interrupted, and the backup summary mode is enabled.

[0163] 2) Enable the standby route: At this time, since the station 1 steady control interface machine A cannot obtain the operation information from the two converters of station 2 pole I and station 2 pole II through the steady control inter-station communication, it cannot accurately calculate the DC power loss in real time to execute the stability strategy, and needs to start the pole control forwarding path (a total of two: station 2 pole I pole control A→ station 1 pole I pole control A→ station 1 steady control interface machine A, station 2 pole II pole control A→ station 1 pole II pole control A→ station 1 steady control interface machine A) to obtain the station 2 converter data.

[0164] 3) Information transmission: Station 2 pole I pole control A forwards the station 2 pole I converter operation information (including converter maximum deliverable power, converter deliverable power instruction value, converter abnormal shutdown signal, converter operating state, and converter normal shutdown signal) to station 1 steady control interface machine A through station 1 pole I pole control A. Pole II is the same.

[0165] 4) Information summary processing: After receiving the station 2 converter data forwarded by the local pole control host (station 1 pole I / II pole control A), the station 1 steady control interface machine A classifies and integrates the information according to the preset priority and logical rules, mainly including:

[0166] Dominant station identification bit check: First, confirm the current pole control dominant station state (such as the default station 1 as the dominant station in the scene, if the station 1 pole control host has not exited, maintain the dominant station identification), ensure that the logic of obtaining the DC overall information (such as power speed drop signal, DC control mode) from the "control pole dominant station value host" is unchanged, and avoid data source confusion caused by communication link switching.

[0167] Converter operation information integration: Match the high-end converter data (station 1 pole I / II converter) collected locally with the low-end converter data (station 2 pole I / II converter) forwarded by the pole control according to "converter number + state type", for example, store the "maximum deliverable power" of station 2 pole I converter and the data of station 1 pole I converter side by side to form a complete four-converter state list.

[0168] Data validity check: Add time stamp and check bit to the forwarded data, if the data deviation between station 2 pole control host and station 1 pole control host historical data exceeds the threshold value (such as power instruction value mutation), trigger local logic compensation (such as using the last valid data or deriving through AC / DC power balance formula), ensure the reliability of the summary data.

[0169] Power loss amount calculation adaptation: In the case of missing direct communication between stability control stations, the power loss amount of each pole is calculated by the "abnormal stop signal" and "maximum deliverable power" of the converter forwarded by the pole control, and the overall power loss amount of the high and low end stations is finally obtained by aggregation, providing the stability control strategy master station with decision basis equivalent to normal working conditions.

[0170] During the whole process, the stability control interface machine A relies on the "inter-station converter operation information forwarding" function of the pole control host, uses the cross-connection structure of the dual configuration pole control host (such as the master-slave communication link between pole I control A of station 1 and pole I control A of station 2), and builds a three-level data transmission chain of "opposite pole control → local pole control → local stability control" when the communication between stability control stations fails, ensuring the integrity of the converter operation information. At the same time, through the "master station identification bit", the core data source (such as the DC power drop signal generated by the on-duty host of the control pole master station) is locked to avoid multi-source data conflict, and the robustness of the "tabular information" aggregation method under complex conditions is realized - that is, whether the communication link is faulty or not, the stability control interface machine can obtain each data field (such as the maximum deliverable power of the converter from the opposite pole control forwarding and the DC control mode from the local master station host) from the specified path according to the preset rules, ensuring the continuity and accuracy of the stability control function.

[0171] Finally, the station 1 stability control interface machine A integrates the whole DC system operation information (including the state of each converter, power loss amount, master station identification, etc.) and synchronizes it to the stability control strategy master station through the redundant channel (such as the second stability interface machine B) of the local stability control interface machine, ensuring that the master station can still execute power modulation, island blocking and other strategies based on complete data when the communication between stability control stations fails.

[0172] Example 3

[0173] Scenario setting: In a series multi-terminal DC system, incomplete pole converter station 1 is the high-end converter station and incomplete pole converter station 2 is the low-end converter station. Station 1 and station 2 each have pole I and pole II converters, and the four converters of the two stations are respectively configured with master and standby pole control hosts; station 1 and station 2 are respectively configured with stability control interface machines. When the communication channel between the DC control and protection stations is interrupted, the pole control interface machines of the high and low ends cannot directly interact data, and the function of the pole control host to aggregate and forward the converter operation information is disabled. However, at this time, since the stability control defaults to collect high and low end information from the communication between stability control stations, the function is not affected.

[0174] Example 4

[0175] Scenario setting: in series multi-terminal DC system, incomplete pole converter station 1 is a high-end converter station, and incomplete pole converter station 2 is a low-end converter station. Station 1 and station 2 have two converters of pole I and pole II respectively, and the four converters of the two stations are respectively configured with master and standby pole control hosts; station 1 and station 2 are respectively configured with stability control interface machines. When the DC system is "cross running", the non-operating converter is in a maintenance state, at this time, the pole control host A / B of station 1 pole I and the pole control host A / B of station 2 pole II are in a running state, and the pole control host A / B of station 1 pole II and the pole control host A / B of station 2 pole I exit the running. At this time, the pole control hosts of the high and low ends are equivalent to be in a communication interruption state, and the function of the pole control host to aggregate and forward the converter operation information is invalid. However, at this time, since the stability control defaults to collect high and low end information by stability control station communication, the function is not affected.

[0176] Compared with the prior art, the beneficial effects of the embodiment of the present application are one of the following:

[0177] 1) By configuring stability control interface machines and pole control hosts in high-end / low-end incomplete pole converter stations in a dual configuration and adopting a cross connection mode, the system of the present application constructs a hardware redundancy and link fault tolerance architecture. When the main equipment or single link fails, the standby equipment or redundant link can immediately take over the function, avoiding the interruption of information collection or the invalidation of control instructions caused by single point failure, and significantly improving the reliability of equipment operation and the stability of data interaction under complex working conditions.

[0178] 2) The double standby communication channels formed by the communication link between the stability control stations and the communication link between the pole control stations realize the redundant backup of double-station information transmission. In normal times, real-time operation data and control instructions are transmitted efficiently according to the division of labor, and when a fault occurs, the channel is automatically switched to ensure that critical information is not lost, effectively solving the system instability problem that may be caused by traditional single-channel communication in link failure, providing double protection for the stable operation of series multi-terminal DC system. Especially in cross-station data integration and abnormal working condition processing, through the complementary cooperation of double links, the overall reliability and anti-interference ability of the system are greatly improved.

[0179] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the present patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A DC voltage stability control system for an incomplete polar series commutation station, characterized by, The application is applied to a series multi-terminal DC system, the series multi-terminal DC system comprises a high-end incomplete pole conversion station, a low-end incomplete pole conversion station and a stability control strategy master station, the high-end incomplete pole conversion station is provided with a first stability control interface machine, a second stability control interface machine and a first pole control master machine, the low-end incomplete pole conversion station is provided with a third stability control interface machine, a fourth stability control interface machine and a second pole control master machine; The first stability control interface machine and the third stability control interface machine are connected with the stability control strategy master station respectively, the first stability control interface machine and the second stability control interface machine are cross-connected with the first pole control master machine, and the third stability control interface machine and the fourth stability control interface machine are cross-connected with the second pole control master machine; The first stability control interface machine of the high-end incomplete pole conversion station is connected with the third stability control interface machine of the low-end incomplete pole conversion station through a stability control station-to-station communication link, the second stability control interface machine of the high-end incomplete pole conversion station is connected with the fourth stability control interface machine of the low-end incomplete pole conversion station through a stability control station-to-station communication link, and the first pole control master machine of the high-end incomplete pole conversion station is connected with the second pole control master machine of the low-end incomplete pole conversion station through a pole control station-to-station communication link; The first stability control interface machine and the third stability control interface machine are further used for: When the stability control station-to-station communication is normal, directly obtaining DC operation data of the local pole control master machine and the opposite pole control master machine through the stability control station-to-station communication link; When the stability control station-to-station communication is faulty, switching to the pole control station-to-station communication link and obtaining the DC operation data through the opposite pole control master machine data forwarded by the local pole control master machine.

2. The DC voltage stability control system of an incomplete polar series commutation station according to claim 1, characterized in that, The first stability control interface machine is used for collecting first AC operation data of the high-end incomplete pole conversion station, and the third stability control interface machine is used for collecting second AC operation data of the low-end incomplete pole conversion station; The second stability control interface machine is used for collecting first DC operation data of the high-end incomplete pole conversion station and first control data of the first pole control master machine, and the fourth stability control interface machine is used for collecting second DC operation data of the low-end incomplete pole conversion station and second control data of the second pole control master machine; the first control data comprises a master station identification bit, DC control mode data and converter operation state data.

3. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 2, characterized in that, The second stability control interface machine and the fourth stability control interface machine are further used for: obtaining DC operation data from a master station pole control master machine based on the master station identification bit; When the master station identification bit indicates that the high-end incomplete pole conversion station is the master station, the master station pole control master machine is the first pole control master machine of the high-end incomplete pole conversion station; when the master station identification bit indicates that the low-end incomplete pole conversion station is the master station, the master station pole control master machine is the second pole control master machine of the low-end incomplete pole conversion station.

4. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 2, wherein, The first stability control interface machine is further used for performing preliminary fusion processing on the collected first AC operation data, the received first DC operation data from the second stability control interface machine and the first control data, and generating high-end station comprehensive data. The third stability interface machine is further configured to perform preliminary fusion processing on the collected second AC operation data and the received second DC operation data and second control data from the fourth stability interface machine to generate low-end station comprehensive data.

5. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 4, wherein, The high-end station comprehensive data or the low-end station comprehensive data each includes corresponding real-time power loss and real-time power modulability; The first stability interface machine and the third stability interface machine are further configured to: analyze the maximum deliverable power, the current actual delivered power and the converter operation state data of each converter in the high-end station comprehensive data and the low-end station comprehensive data to obtain the real-time power loss; and analyze the adjustable power range of each converter in the high-end station comprehensive data and the low-end station comprehensive data under the current working condition to obtain the real-time power modulability. The first stability interface machine is further configured to upload the high-end station comprehensive data to the stability control strategy master station, and the third stability interface machine is further configured to upload the low-end station comprehensive data to the stability control strategy master station.

6. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 4, wherein, The first stability interface machine and the third stability interface machine exchange the high-end station comprehensive data and the low-end station comprehensive data through a stability control station-to-station communication link. The stability control strategy master station is configured to:

7. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 6, wherein, receive the high-end station comprehensive data and the low-end station comprehensive data, analyze the high-end station comprehensive data and the low-end station comprehensive data, and generate control instructions corresponding to the analysis results; and the control instructions include, but are not limited to, power adjustment instructions for the high-end incomplete pole converter station and the low-end incomplete pole converter station, converter control instructions and parameter adjustment instructions for the pole control master machine. The stability control strategy master station is further configured to: perform comparison processing on the high-end station comprehensive data and the low-end station comprehensive data, and if the comparison result shows that the data is consistent, the trend is normal and the correlation meets the expectation, generate comprehensive operation data of the series multi-terminal DC system; otherwise, match the comparison processing result with a pre-constructed fault database, and generate a stability control adjustment strategy according to the matching result.

8. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 7, wherein, The stability control strategy master station is further configured to send the control instructions to the first stability interface machine and the third stability interface machine. The first stability interface machine is further configured to send the control instructions related to the high-end incomplete pole converter station to the second stability interface machine and the first pole control master machine, and the third stability interface machine is further configured to send the control instructions related to the low-end incomplete pole converter station to the fourth stability interface machine and the second pole control master machine. ​ 9. The DC voltage stability control system of an incomplete polar series commutation station as claimed in claim 7, wherein, ​ ​

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