Direct current voltage coordinated control method and system
By pre-setting a DC voltage deviation slope control strategy in the polarity control protection device, the flexible DC system can achieve rapid transient voltage stabilization and active power redistribution when communication is abnormal, thus solving the voltage instability problem caused by communication dependence and ensuring stable system operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NR ELECTRIC CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-05-29
AI Technical Summary
When communication is interrupted or abnormal, the coordination capability of flexible DC transmission systems decreases, which can easily lead to DC voltage instability and affect the safe operation of the system. In particular, in multi-terminal DC systems, it may trigger a chain reaction, causing voltage fluctuations or even system shutdown.
A DC voltage deviation slope control strategy is preset in the polarity control protection device. Rapid transient voltage stabilization is achieved through local slope control without relying on continuous inter-station communication. Combined with multiple criteria and delay mechanisms, the active power is automatically redistributed to ensure stable operation of the system when communication is abnormal.
It can operate stably under both normal and abnormal communication conditions, which improves the operational stability and fault self-healing capability of the flexible DC system, avoids DC voltage runaway caused by communication failure, and enhances the system's reliability and anti-interference capability.
Smart Images
Figure CN122118892A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of flexible DC transmission technology in power systems, specifically to DC voltage coordination control methods and systems. Background Technology
[0002] In flexible DC transmission systems, stable DC voltage control is typically achieved through inter-station coordinated control. These control methods are highly dependent on the communication system; when communication is interrupted or abnormal, the system's coordination capability decreases, easily leading to DC voltage instability and affecting the safe operation of the system. Especially in multi-terminal DC systems, a communication anomaly at one station or in one area can trigger a chain reaction, causing voltage fluctuations or even system shutdowns. Summary of the Invention
[0003] This application provides a DC voltage coordinated control method and system, aiming to solve the problem of excessive reliance on communication in related technologies.
[0004] Firstly, a DC voltage coordinated control method is provided for coordinating DC voltage control of a flexible DC system. The flexible DC system includes at least two DC transmission converter stations, each including a DC voltage control station and a power control station. Both the DC voltage control station and the power control station are equipped with pole control protection devices, which are pre-set with a DC voltage deviation slope control strategy. The DC voltage coordinated control method includes: When the DC voltage is stabilized by the DC voltage control station, the converter of this station is controlled to operate at the set power by the pole control protection device of each of the power control stations; In the event of a DC voltage disturbance, the pole control protection device of each power control station adjusts the output power of the converter at that station according to the preset slope in the DC voltage deviation slope control strategy to help stabilize the DC voltage. If the flexible DC system is detected to be in a communication abnormality state, and the DC voltage is abnormal, then the satisfaction of the preset criterion corresponding to the communication abnormality state is determined. If the preset criteria are met, the exception handling logic corresponding to the communication exception state is executed, and the exception handling logic at least indicates the redistribution of active power.
[0005] In some embodiments, the communication abnormality is a communication abnormality of the pole control protection device of the power control station. The power control station with communication abnormality is connected to the DC station control device in the non-DC voltage control area where it is located. The DC station control device is connected to the coordination control device for system-level coordination control. The preset criteria are: the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value, and the duration of the identifier bit being the target value is not less than a first preset delay; and the DC current of the power control station with abnormal communication is less than a first preset threshold; wherein, the target value represents the start of DC voltage deviation slope control. Specifically, the abnormal handling logic involves redistributing active power through the DC station control device or the coordination control device.
[0006] In some embodiments, the communication abnormality is a communication abnormality of the pole control protection device of the DC voltage control station, and the DC voltage control station is connected to the DC station control device of the DC voltage control area where it is located. The preset criteria are: the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value, and the duration of the identifier bit being the target value is not less than a second preset delay, and the DC current of the DC voltage control station is less than a second preset threshold; wherein, the target value represents the start of DC voltage deviation slope control. The specific exception handling logic is as follows: the DC station control device determines the target power control station among the power control stations, transfers the DC voltage control authority to the target power control station, and performs a redistribution of active power.
[0007] In some embodiments, each of the power control stations is preset with DC voltage control priority; Determining the target power control station among the aforementioned power control stations includes: The target power control station is determined among the power control stations in descending order of DC voltage control priority.
[0008] In some embodiments, transferring DC voltage control to the target power control station includes: The DC station control device sends a DC voltage control takeover signal to the target power control station.
[0009] In some embodiments, the communication anomaly is a communication anomaly of the DC station control device in the DC voltage control area; The preset criterion is that the flag bit representing the DC voltage deviation slope control in the non-DC voltage control region is the target value, and the duration of the flag bit being the target value is not less than a third preset delay, and the target value represents the start of DC voltage deviation slope control. The specific exception handling logic is as follows: the DC station control device in the non-DC voltage control area takes over the DC voltage control right, determines the target power control station in each of the power control stations, allocates the DC voltage control right to the target power control station, and performs a redistribution of active power.
[0010] In some embodiments, the communication anomaly is a communication anomaly of the DC station control device in a non-DC voltage control area, or a communication anomaly of the coordination control device used for system-level coordination control. The preset criterion is that the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value, and the duration of the identifier bit being the target value is not less than the fourth preset delay, and the target value represents the start of DC voltage deviation slope control. The specific abnormality handling logic is as follows: a preset backup control device takes over the DC voltage coordination control of the DC station control device or the coordination control device when communication is abnormal, and performs a redistribution of active power.
[0011] In some embodiments, after the DC voltage abnormality is detected, the method further includes: The DC voltage deviation slope control strategy is activated by the pole control protection device of each of the power control stations.
[0012] In a second aspect, a DC voltage coordination control system is provided for performing DC voltage coordination control on a flexible DC system using a DC voltage coordination control method as described in any implementation of the first aspect, wherein the flexible DC system includes at least two DC transmission converter stations, and the at least two DC transmission converter stations include a DC voltage control station and a power control station; the DC voltage coordination control system includes: Multiple pole control protection devices are respectively installed in the DC voltage control station and the power control station, and a DC voltage deviation slope control strategy is preset. The pole control protection devices of each power control station are used to control the converter of the station to operate at a set power when the DC voltage is stabilized by the DC voltage control station, and to adjust the output power of the converter of the station to assist in stabilizing the DC voltage when the DC voltage is disturbed, according to the preset slope in the DC voltage deviation slope control strategy. A communication status detection module is used to detect the communication status of the flexible DC system in real time. The decision module is used to determine whether a preset criterion corresponding to the communication abnormality is met when the flexible DC system is detected to be in a communication abnormality state, if the DC voltage is abnormal, and to execute the abnormality handling logic corresponding to the communication abnormality state when the preset criterion is met, wherein the abnormality handling logic at least indicates the redistribution of active power.
[0013] In some embodiments, the DC voltage coordination control system further includes: At least one DC station control device for coordinated control within the area; At least one coordination control device for system-level coordination control.
[0014] In some embodiments, the decision-making module includes a criterion execution unit, which is disposed in the DC station control device and is used for: The system receives and determines the identifier bit and DC current value representing the DC voltage deviation slope control from the polarity control protection device, and sends a control capability loss signal or control takeover command to the coordination control device when the preset criteria are met.
[0015] In some embodiments, the decision-making module includes a global decision-making unit, which is disposed in the coordination and control device and is used for: Upon receiving a signal indicating loss of control capability or a control takeover command from the DC station control device, the system makes a decision and triggers cross-regional control takeover and redistribution of active power across the entire system based on global status information.
[0016] In summary, the solution provided in this application is used for coordinated DC voltage control of a flexible DC system. The flexible DC system includes at least two DC transmission converter stations, each comprising a DC voltage control station and a power control station. Both the DC voltage control station and the power control station are equipped with pole control protection devices, which are pre-programmed with a DC voltage deviation slope control strategy. In this solution, when the DC voltage is stable under the control of the DC voltage control station, the pole control protection devices of each power control station control the converters at that station to operate at a set power. When DC voltage disturbances occur, the pole control protection devices of each power control station adjust the output power of the converters at that station according to the pre-programmed slope in the DC voltage deviation slope control strategy to assist in stabilizing the DC voltage. In this solution, the DC voltage deviation slope control strategy works regardless of whether communication is present. By pre-programming the DC voltage deviation slope control strategy in the pole control protection devices, rapid transient voltage stabilization can be achieved through local slope control, without relying on continuous inter-station communication. By detecting a communication anomaly in the flexible DC system and responding to an abnormal DC voltage, the system determines whether a preset criterion for the communication anomaly is met. If the preset criterion is met, the system executes the corresponding anomaly handling logic. This anomaly handling logic at least instructs the redistribution of active power. This automatic execution of active power redistribution and other anomaly handling logic after prolonged communication anomalies and before manual intervention by maintenance personnel improves DC voltage stability. Therefore, this solution ensures stable operation of the flexible DC system under both normal and abnormal communication conditions. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram illustrating the principle of the DC voltage deviation slope control strategy provided in this application embodiment under steady-state and transient modes; Figure 2 This is a schematic flowchart of a DC voltage coordinated control method provided in an embodiment of this application; Figure 3 This is a control flowchart provided in an embodiment of the present application when the pole control protection device of the power control station experiences a communication malfunction. Figure 4 This is a control flowchart provided in the embodiments of this application when the pole control protection device of the DC voltage control station experiences a communication malfunction; Figure 5This is a schematic diagram of the DC voltage coordination control system provided in the embodiments of this application. Detailed Implementation
[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0020] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.
[0021] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.
[0022] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more conditions or values may in practice be based on additional conditions or values beyond those stated.
[0023] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.
[0024] In flexible DC transmission systems, stable DC voltage control is typically achieved through inter-station coordinated control. Existing control methods heavily rely on communication systems; when communication is interrupted or abnormal, system coordination capabilities decline, easily leading to DC voltage instability and affecting system safety. Especially in multi-terminal DC systems, communication anomalies at one station or in one area can trigger a chain reaction, causing voltage fluctuations or even system shutdowns. While some backup control strategies exist in existing technologies, they often lack systematic coordination and seamless takeover solutions for different levels and types of communication anomalies, resulting in insufficient reliability, speed, and smoothness in handling complex abnormal operating conditions.
[0025] In view of this, the present application provides a DC voltage coordinated control method and system. By pre-setting a DC voltage deviation slope control strategy in the polarity control protection device, it can achieve rapid transient voltage stabilization through local slope control, without relying on continuous inter-station communication, and ensure that the flexible DC system can operate stably under both normal and abnormal communication conditions, thereby solving at least one of the above-mentioned technical problems.
[0026] In some embodiments of this application, the flexible DC system includes at least two DC transmission converter stations, each comprising a DC voltage control station and a power control station. Both the DC voltage control station and the power control station are equipped with pole control protection devices, which are pre-set with a DC voltage deviation slope control strategy. This DC voltage deviation slope control strategy includes a preset slope, which is the slope of active power change with DC voltage.
[0027] Figure 1 This is a schematic diagram illustrating the principle of the DC voltage deviation slope control strategy provided in this application under steady-state and transient modes. The DC voltage deviation slope control strategy adopted in this application is as follows: Figure 1 As shown, in steady state ( Figure 1 In the steady-state operating mode (a), the DC voltage control station maintains voltage stability, and each power control station operates according to the set power; during transient mode (a) Figure 1 In the transient operating mode (b), when a DC voltage disturbance occurs, the power control station enters the slope control range, adjusting the output power of the station's converter to assist in stabilizing the voltage. After the disturbance is eliminated, constant power control is restored. Figure 1 In P d1 , P d2 , P d3 Representing the active power of different DC transmission converter stations (or power sources), in Figure 1 The value is represented by the x-coordinate intercept or working point of three diagonal lines. U dref1 This represents the DC voltage reference value. Figure 1 Multiple diagonal lines intersect at U dref1 The point indicates that, under steady-state operating mode, all DC transmission converter stations involved in the control work together to maintain the voltage stability target. U d1、 U d2、 U d3 This represents the DC voltage at different DC transmission converter stations. The slope of the line indicates the voltage adjustment coefficient as power changes.
[0028] Brief description of working principle: Figure 1 (a) Steady-state operating mode: The U / P characteristic curves of all DC transmission converter stations intersect at the same point. U dref1 Under this voltage, the system shares the load power according to its respective capacity ratio. P d1 , P d2 , P d3 .
[0029] Figure 1 (b) Transient operating mode: When the load changes or disturbances occur, each DC transmission converter station automatically adjusts its power output through the "droop" characteristic (i.e., the voltage decreases as the power increases), and eventually stabilizes at a new DC voltage point. U dref1 This enables adaptive power allocation without the need for communication.
[0030] Figure 2 This is a schematic flowchart of a DC voltage coordinated control method provided in an embodiment of this application. Figure 2 As shown, the DC voltage coordinated control method includes steps S201 to S207 as shown below.
[0031] In step S201, under the condition that the DC voltage is stable under the control of the DC voltage control station, the converter of this station is controlled to operate at the set power by the pole control protection device of each power control station.
[0032] As an example, the DC voltage control station maintains voltage stability. The pole control and protection (PCP) of each power control station can detect that the DC voltage of the flexible DC system is within a preset normal voltage range, and thus know that the DC voltage is in a steady state. This allows the station's converter to operate at the set power without additional power regulation.
[0033] In step S203, when a DC voltage disturbance occurs, the output power of the converter of each power control station is adjusted according to the preset slope in the DC voltage deviation slope control strategy by the pole control protection device of each power control station to help stabilize the DC voltage.
[0034] Specifically, the pole control protection device of each power control station can respond to DC voltage disturbances, such as DC voltage disturbances caused by a sudden increase in load in a flexible DC system, and adjust the output power of the converter of this station according to the preset slope in the DC voltage deviation slope control strategy to help stabilize the DC voltage.
[0035] For example, the pole control protection device of each power control station can collect the DC voltage deviation value (the deviation between the actual DC voltage and the rated DC voltage) in real time. Based on this DC voltage deviation value, it determines whether a DC voltage disturbance has occurred. After determining that a DC voltage disturbance has occurred, it activates a preset DC voltage deviation slope control strategy, and then determines the power regulation amount based on the preset slope and the DC voltage deviation value. The power regulation amount is then adjusted according to this power regulation amount, which can be the product of the preset slope and the DC voltage deviation value.
[0036] In step S205, if the flexible DC system is detected to be in a communication abnormal state, and the DC voltage is abnormal, the satisfaction of the preset criteria corresponding to the communication abnormal state is determined.
[0037] In step S207, if the preset criteria are met, the exception handling logic corresponding to the communication exception state is executed. The exception handling logic at least indicates the redistribution of active power.
[0038] The preset criteria can be used to determine whether control takeover and power redistribution are necessary. By executing steps S205 and S207, control actions can be precisely triggered through preset criteria in cases of communication anomalies between stations / station control layers or DC voltage instability, preventing DC voltage runaway caused by communication failures. Moreover, relying on automatic criteria and power redistribution mechanisms, the system power balance can be quickly reconstructed without manual intervention, improving DC voltage stability. At the same time, criterion screening effectively avoids false triggering, improves the reliability and anti-interference of control logic, ensures the safe and continuous operation of the flexible DC system in communication anomaly scenarios, and significantly improves the operational stability and fault self-healing capability of multi-terminal flexible DC systems.
[0039] exist Figure 2 In the corresponding embodiment, the DC voltage deviation slope control strategy works regardless of whether communication is present. By pre-setting the DC voltage deviation slope control strategy in the pole control protection device, rapid transient voltage stabilization can be achieved through local slope control, independent of continuous inter-station communication. When a communication anomaly is detected in the flexible DC system, in response to the DC voltage anomaly, the system determines whether a preset criterion corresponding to the communication anomaly is met. If the preset criterion is met, the system executes the anomaly handling logic corresponding to the communication anomaly. The anomaly handling logic at least instructs the redistribution of active power. This allows for automatic execution of active power redistribution and other anomaly handling logic after a prolonged communication anomaly and before manual intervention by maintenance personnel, improving DC voltage stability. Therefore, this solution ensures stable operation of the flexible DC system under both normal and abnormal communication conditions.
[0040] In some embodiments, the flexible DC system is divided into a DC voltage control area and a non-DC voltage control area. Both the DC voltage control area and the non-DC voltage control area are equipped with direct current control (DCC) devices. A DC voltage control station is located in the DC voltage control area and is communicatively connected to the DC voltage control device there. Each power control station is located in the non-DC voltage control area and is communicatively connected to the DC voltage control device there. Furthermore, the DC voltage control devices in both the DC voltage control area and the non-DC voltage control area are also communicatively connected to a station coordinated control (SCC) device used for system-level coordinated control. The aforementioned communication anomalies may include at least one of the following: communication anomalies in the pole control protection devices of the power control stations, communication anomalies in the pole control protection devices of the DC voltage control stations, communication anomalies in the DC voltage control area's DC voltage control device, communication anomalies in the non-DC voltage control area's DC voltage control device, and communication anomalies in the coordinated control device.
[0041] Figure 3This is a control flowchart provided in an embodiment of this application when the pole control protection device of the power control station experiences a communication malfunction. In the case where the aforementioned communication malfunction is a communication malfunction of the pole control protection device of the power control station, such as... Figure 3 As shown, the preset criteria can be that the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is a target value (e.g., 1), and the duration of the identifier bit being the target value is not less than a first preset delay, and the DC current of the power control station with abnormal communication is less than a first preset threshold; wherein, the target value represents the start of DC voltage deviation slope control; the abnormal handling logic can specifically be that the active power is redistributed through the DC station control device or coordination control device in the non-DC voltage control area where the power control station with abnormal communication is located.
[0042] Furthermore, such as Figure 3 As shown, if the communication abnormality is due to a communication abnormality in the pole control protection device of the power control station, and the DC voltage is normal, the flexible DC system will maintain its original control mode.
[0043] As one implementation method, when the DC station control device or coordination control device in the non-DC voltage control area where the power control station with communication failure is located performs the redistribution of active power, the wind turbine can be cut off when necessary. For example, when there is too much power surplus that cannot be absorbed, the wind turbine can be cut off by disconnecting the switch connected to the wind turbine.
[0044] Figure 4 This is a control flowchart provided in an embodiment of this application when the pole control protection device of a DC voltage control station experiences a communication malfunction. In the case where the aforementioned communication malfunction is a communication malfunction of the pole control protection device of the DC voltage control station, such as... Figure 4 As shown, the preset criteria can be that the identifier bit representing the DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value (e.g., 1), and the duration of the identifier bit being the target value is not less than the second preset delay, and the DC current of the DC voltage control station is less than the second preset threshold; wherein, the target value represents the start of DC voltage deviation slope control; the abnormal handling logic can be specifically as follows: the DC station control device in the DC voltage control area determines the target power control station in each power control station, transfers the DC voltage control right to the target power control station, and performs the redistribution of active power.
[0045] For example, each power control station has a preset DC voltage control priority. The DC station control device in the DC voltage control area can determine the target power control station among the power control stations according to the DC voltage control priority from high to low. It should be understood that the target power control station is the power control station with the highest DC voltage control priority. After determining the target power control station, the DC station control device can issue a DC voltage control takeover signal to the target power control station and perform active power redistribution.
[0046] It should be noted that, in Figure 4 In the corresponding example, the DC voltage anomaly is caused by the failure of the DC voltage control station. In some embodiments, when the aforementioned communication anomaly is a communication failure of the pole control protection device of the DC voltage control station, if the DC voltage control station fails, i.e., the DC power supply is abnormal, the DC voltage deviation slope control strategy of each power control station is activated. It should be understood that the pole control protection device of each power control station activates the DC voltage deviation slope control strategy.
[0047] In some embodiments, the above-mentioned communication abnormality is a communication abnormality of the DC station control device in the DC voltage control area; the preset criterion can be that the flag bit representing the DC voltage deviation slope control in the non-DC voltage control area is a target value (e.g., 1), and the duration of the flag bit being a target value is not less than a third preset delay, and the target value represents the start of DC voltage deviation slope control; the abnormality handling logic can be specifically as follows: the DC station control device in the non-DC voltage control area takes over the DC voltage control right, determines the target power control station in each power control station, allocates the DC voltage control right to the target power control station, and performs the redistribution of active power.
[0048] In some embodiments, the aforementioned communication anomaly refers to a communication anomaly in the DC station control device in a non-DC voltage control area, or a communication anomaly in the coordination control device. A preset criterion can be that the flag bit representing DC voltage deviation slope control sent by a normally communicating DC transmission converter station is a target value (e.g., 1), and the duration of this flag bit being the target value is not less than a fourth preset delay. The target value represents the activation of DC voltage deviation slope control. The anomaly handling logic can specifically involve a preset backup control device taking over the DC voltage coordination control rights of the DC station control device or coordination control device with communication anomalies, and performing active power redistribution. Specifically, when the DC station control device in a non-DC voltage control area has a communication anomaly, the preset backup control device can be the coordination control device. When the coordination control device has a communication anomaly, the preset backup control device can be the DC station control device in a non-DC voltage control area. Optionally, in the event of a DC voltage anomaly, the DC voltage deviation slope control strategy is activated through the pole control protection device of each power control station.
[0049] It should be noted that, as mentioned above, the first, second, third, and fourth preset delays are all no less than S seconds, where S ≥ 0. The first and second preset thresholds can both be N% of the rated DC current, with 0 ≤ N ≤ 100.
[0050] The solution provided in this application constructs a layered collaborative control and automatic takeover mechanism to address various communication anomalies that may occur in DC voltage control stations, power control stations, DC station control devices, and coordination control devices. Its core lies in deploying a DC voltage deviation slope control strategy independent of inter-station communication in the pole control protection devices of the DC voltage control station and power control station. This strategy enables the system to operate in constant power mode during steady state and assists in voltage stabilization through slope characteristics when DC voltage disturbances occur. When a prolonged communication anomaly occurs and threatens voltage stability, a control takeover and power redistribution process led by SCC or DCC is automatically triggered based on preset criteria. This application effectively solves the problem of excessive reliance on communication in related technologies. Under communication anomaly conditions, it can both quickly suppress transient voltage fluctuations using local control and achieve a smooth transfer of control through reliable logical judgment, significantly improving the operational reliability and voltage stability of multi-terminal DC systems. It should be understood that by introducing the DC voltage deviation slope control strategy and corresponding communication anomaly takeover logic, DC voltage stability can be maintained in both transient and steady-state processes.
[0051] In summary, the solutions provided in this application have the following beneficial effects: Voltage transient stabilization can be achieved without relying on continuous communication; By employing multiple criteria and delay mechanisms, erroneous actions are avoided, and the reliability of takeover is improved. Supports automatic coordination and power reallocation in various communication anomaly scenarios; It is compatible with existing control architectures and is easy to implement and upgrade.
[0052] Figure 5 This is a schematic diagram of the DC voltage coordination control system provided in an embodiment of this application. The DC voltage coordination control system is used to perform DC voltage coordination control on a flexible DC system using the DC voltage coordination control method described above. The flexible DC system includes at least two DC transmission converter stations, each including a DC voltage control station and a power control station. Figure 5 As shown, the DC voltage coordination control system includes: Multiple pole control protection devices are respectively installed in the DC voltage control station and the power control station, and a DC voltage deviation slope control strategy is preset. The pole control protection device of each power control station is used to control the converter of the station to operate at a set power when the DC voltage is stable under the control of the DC voltage control station, and to adjust the output power of the converter of the station to assist in stabilizing the DC voltage when the DC voltage is disturbed. The communication status detection module is used to detect the communication status of the flexible DC system in real time. The decision module is used to determine whether the preset criteria corresponding to the communication abnormality state are met when the flexible DC system is detected to be in a communication abnormality state, if the DC voltage is abnormal. When the preset criteria are met, the abnormality handling logic corresponding to the communication abnormality state is executed. The abnormality handling logic at least indicates the redistribution of active power.
[0053] In some embodiments, the DC voltage coordination control system further includes: at least one DC station control device for regional coordination control; and at least one coordination control device for system-level coordination control. Further, the at least one DC station control device is also used for communication status detection.
[0054] For example, the communication status detection module is used to detect the communication status between the pole control protection device, the DC station control device, and the coordination control device in real time.
[0055] In some embodiments, the decision-making module includes a criterion execution unit, which is disposed in the DC station control device and the coordination control device, and is used for: It receives and judges the flag bit and DC current value representing the DC voltage deviation slope control from the polarity control protection device, and allocates DC voltage control rights to the target power control station when the preset criteria are met, and performs active power redistribution.
[0056] In some embodiments, the decision-making module includes a global decision-making unit, which is disposed in the coordination and control device and is used for: Upon receiving a signal indicating loss of control capability or a control takeover command from the DC station control device, the system makes a decision and triggers cross-regional control takeover and redistribution of active power across the entire system based on global status information.
[0057] In some embodiments, the pole control protection device has a built-in deviation slope control module. The deviation slope control module of the pole control protection device of each power control station is used to control the converter of the station to operate at a set power when the DC voltage is stable under the control of the DC voltage control station, and to adjust the output power of the converter of the station to assist in stabilizing the DC voltage when the DC voltage is disturbed, according to the preset slope in the DC voltage deviation slope control strategy.
[0058] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0059] The above provides a detailed description of a DC voltage coordinated control method and system provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A DC voltage coordinated control method, characterized in that, This is used for DC voltage coordinated control of a flexible DC system, the flexible DC system including at least two DC transmission converter stations, the at least two DC transmission converter stations including a DC voltage control station and a power control station, the DC voltage control station and the power control station are both equipped with pole control protection devices, the pole control protection devices are preset with DC voltage deviation slope control strategies; The DC voltage coordinated control method includes: When the DC voltage is stabilized by the DC voltage control station, the converter of this station is controlled to operate at the set power by the pole control protection device of each of the power control stations; In the event of a DC voltage disturbance, the pole control protection device of each power control station adjusts the output power of the converter at that station according to the preset slope in the DC voltage deviation slope control strategy to help stabilize the DC voltage. If the flexible DC system is detected to be in a communication abnormality state, and the DC voltage is abnormal, then the satisfaction of the preset criterion corresponding to the communication abnormality state is determined. If the preset criteria are met, the exception handling logic corresponding to the communication exception state is executed, and the exception handling logic at least indicates the redistribution of active power.
2. The DC voltage coordinated control method according to claim 1, characterized in that, The communication abnormality is that the pole control protection device of the power control station has a communication abnormality. The power control station with the communication abnormality is connected to the DC station control device in the non-DC voltage control area. The DC station control device is connected to the coordination control device for system-level coordination control. The preset criteria are: the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value, and the duration of the identifier bit being the target value is not less than a first preset delay; and the DC current of the power control station with abnormal communication is less than a first preset threshold; wherein, the target value represents the start of DC voltage deviation slope control. Specifically, the abnormal handling logic involves redistributing active power through the DC station control device or the coordination control device.
3. The DC voltage coordinated control method according to claim 1, characterized in that, The communication abnormality is that the pole control protection device of the DC voltage control station is in communication abnormality, and the DC voltage control station is connected to the DC station control device of the DC voltage control area it is located in. The preset criteria are: the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value, and the duration of the identifier bit being the target value is not less than a second preset delay, and the DC current of the DC voltage control station is less than a second preset threshold; wherein, the target value represents the start of DC voltage deviation slope control. The specific exception handling logic is as follows: the DC station control device determines the target power control station among the power control stations, transfers the DC voltage control authority to the target power control station, and performs a redistribution of active power.
4. The DC voltage coordinated control method according to claim 3, characterized in that, Each of the power control stations is preset with DC voltage control priority; Determining the target power control station among the aforementioned power control stations includes: The target power control station is determined among the power control stations in descending order of DC voltage control priority.
5. The DC voltage coordinated control method according to claim 3, characterized in that, Transferring DC voltage control to the target power control station includes: The DC station control device sends a DC voltage control takeover signal to the target power control station.
6. The DC voltage coordinated control method according to claim 1, characterized in that, The communication anomaly is a communication anomaly of the DC station control device in the DC voltage control area. The preset criterion is that the flag bit representing the DC voltage deviation slope control in the non-DC voltage control region is the target value, and the duration of the flag bit being the target value is not less than a third preset delay, and the target value represents the start of DC voltage deviation slope control. The specific exception handling logic is as follows: the DC station control device in the non-DC voltage control area takes over the DC voltage control right, determines the target power control station in each of the power control stations, allocates the DC voltage control right to the target power control station, and performs a redistribution of active power.
7. The DC voltage coordinated control method according to claim 1, characterized in that, The communication anomaly refers to a communication anomaly in the DC station control device in the non-DC voltage control area, or a communication anomaly in the coordination control device used for system-level coordination control. The preset criterion is that the identifier bit representing DC voltage deviation slope control sent by the DC transmission converter station with normal communication is the target value, and the duration of the identifier bit being the target value is not less than the fourth preset delay, and the target value represents the start of DC voltage deviation slope control. The specific abnormality handling logic is as follows: a preset backup control device takes over the DC voltage coordination control of the DC station control device or the coordination control device when communication is abnormal, and performs a redistribution of active power.
8. The DC voltage coordinated control method according to claim 3 or 7, characterized in that, Following the statement about an abnormal DC voltage, the following is also included: The DC voltage deviation slope control strategy is activated by the pole control protection device of each of the power control stations.
9. A DC voltage coordination control system, characterized in that, A method for coordinating DC voltage control of a flexible DC system using the DC voltage coordination control method as described in any one of claims 1-8, wherein the flexible DC system includes at least two DC transmission converter stations, and the at least two DC transmission converter stations include a DC voltage control station and a power control station; the DC voltage coordination control system includes: Multiple pole control protection devices are respectively installed in the DC voltage control station and the power control station, and a DC voltage deviation slope control strategy is preset. The pole control protection devices of each power control station are used to control the converter of the station to operate at a set power when the DC voltage is stabilized by the DC voltage control station, and to adjust the output power of the converter of the station to assist in stabilizing the DC voltage when the DC voltage is disturbed. A communication status detection module is used to detect the communication status of the flexible DC system in real time. The decision module is used to determine whether a preset criterion corresponding to the communication abnormality is met when the flexible DC system is detected to be in a communication abnormality state, if the DC voltage is abnormal, and to execute the abnormality handling logic corresponding to the communication abnormality state when the preset criterion is met, wherein the abnormality handling logic at least indicates the redistribution of active power.
10. The DC voltage coordination control system according to claim 9, characterized in that, Also includes: At least one DC station control device for coordinated control within the area; At least one coordination control device for system-level coordination control.
11. The DC voltage coordination control system according to claim 10, characterized in that, The decision-making module includes a criterion execution unit, which is disposed in the DC station control device and the coordination control device, and is used for: The system receives and determines the identifier bit and DC current value representing the DC voltage deviation slope control from the polarity control protection device. When the preset criteria are met, the system allocates DC voltage control rights to the target power control station and redistributes active power.
12. The DC voltage coordination control system according to claim 10, characterized in that, The decision-making module includes a global decision-making unit, which is located in the coordination and control device and is used for: Upon receiving a signal indicating loss of control capability or a control takeover command from the DC station control device, the system makes a decision and triggers cross-regional control takeover and redistribution of active power across the entire system based on global status information.