UHV DC online valve group withdrawal method and system with adaptive trigger angle change

Abstract

The present invention provides a method and system for online valve group withdrawal in UHV DC with adaptive trigger angle change. The method is to respond to a single valve group blocking instruction. The inverter station sends a blocking execution instruction to the rectifier station and configures the integration duration of the trigger angle limiter on the inverter side and the delayed blocking execution time according to the steady-state trigger angle on the inverter side, the AC voltage volatility, the AC frequency deviation, and the communication delay between stations. When the delayed blocking execution time arrives, an inverter side blocking process including adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the inverter side is executed. When the rectifier station receives the blocking execution instruction, it configures the integration duration of the trigger angle limiter on the rectifier side according to the steady-state trigger angle on the rectifier side and the DC current change rate and immediately executes a rectifier side blocking process including adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the rectifier side. The present invention can reduce the disturbance caused by online valve group withdrawal to the system and effectively improve the operation stability of the AC-DC power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of UHV DC power transmission, and particularly to a method and system for online valve group withdrawal of UHV DC with adaptive trigger angle change. Background Art

[0002] The UHV DC converter station is configured with a single pole and two valve groups. When the two valve groups are unlocked and operating, it is allowed to withdraw one of the valve groups online. In the normal process of online withdrawal of the converter, after the valve group withdrawal command is issued, the trigger angle ALPHA_90 command (the locking time sequence command for moving the trigger angle to 90°) is sent to the converter to be withdrawn, so that the voltage across the converter is zero; then the bypass pair is put into operation, and the bypass breaker BPS (Bidirectional Power Switch) switch is closed to reduce the current flowing through the converter to zero; finally, the trigger pulse of the converter to be withdrawn is blocked. The specific online withdrawal process of the converter is as Figure 1 shown. First, the inverter-side converter is withdrawn, and then the rectifier-side converter is withdrawn to ensure that the voltage on the inverter side is not higher than that on the rectifier side during the online withdrawal process of the converter, and the current transmission of the in-service converter valve is not affected.

[0003] However, when the existing UHV DC withdraws the valve group online, both the rectifier side and the inverter side execute the command to move the trigger angle to 90° at a fixed rate simultaneously. However, the initial trigger angle angles of the rectifier side and the inverter side in actual operation are not the same (the operating range of the trigger angle on the rectifier side is 12.5° - 17.5°, and the operating range of the extinction angle on the inverter side is 17.5° - 21.5°), which will result in inconsistent durations for the trigger angles on both sides to move to 90°; in addition, the redundant communication loop mechanism and communication delay problems adopted between stations will also cause the problem that the starting moments of the rectifier side and the inverter side to execute the trigger angle movement command are inconsistent. That is, the existing UHV online valve group withdrawal method will cause different trigger angle change rates on the rectifier side and the inverter side, and further cause inconsistent voltage changes at the two stations, which not only causes a large disturbance to the DC current, but also affects the stability of the DC voltage and current when the bypass pair is put into operation. Summary of the Invention

[0004] The object of the present invention is to provide a method for online valve group withdrawal of UHV DC with adaptive trigger angle change. By combining the alignment mechanism of the execution time of the valve group locking instructions on both sides that delays the execution time of the shift trigger angle on the inverter side based on the inter-station communication delay with the adaptive synchronous trigger angle change mechanism that adaptively and reasonably configures the integration duration of the trigger angle limiters on the inverter side and the rectifier side based on the real-time operating conditions of the UHV DC transmission system and the AC system, when actually executing the valve group locking instruction, the starting moments of the angle shift on the rectifier side and the inverter side can be effectively aligned, and the duration consistency of the angle shift to 90° on both sides can be ensured, realizing the adaptive synchronization of the trigger angle change on both sides, effectively reducing the disturbance to the DC system caused by valve group withdrawal during operation, and further improving the operating stability of the AC-DC power grid.

[0005] To achieve the above object, a method and system for online valve group withdrawal of UHV DC with adaptive trigger angle change are provided.

[0006] In a first aspect, an embodiment of the present invention provides a method for online valve group withdrawal of UHV DC with adaptive trigger angle change, the method comprising the following steps:

[0007] In response to a single valve group locking instruction, the inverter station sends a locking execution instruction to the corresponding rectifier station, and configures the integration duration of the trigger angle limiter on the inverter side and delays the locking execution moment according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay, and executes the locking process on the inverter side when the delayed locking execution moment is reached; the locking process on the inverter side includes adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the inverter side;

[0008] When the rectifier station receives the locking execution instruction, it configures the integration duration of the trigger angle limiter on the rectifier side according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate, and immediately executes the locking process on the rectifier side; the locking process on the rectifier side includes adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the rectifier side.

[0009] Further, the step of configuring the integration duration of the trigger angle limiter on the inverter side and delaying the locking execution moment according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay includes:

[0010] Adjust the preset target angle movement duration according to the steady-state trigger angle on the inverter side, the AC voltage volatility, and the AC frequency deviation to obtain a first integration duration, and configure the first integration duration as the integration time constant in the corresponding trigger angle limiter on the inverter side;

[0011] Obtain the delayed locking execution moment according to the sum of the inter-station communication delay and the receiving moment corresponding to the single valve group locking instruction.

[0012] Further, the first integration duration is expressed as:

[0013]

[0014] In the formula, represents the first integration duration; represents the preset target angle movement duration; and represent constant coefficients; and represent the AC voltage volatility and the AC frequency deviation respectively; represents the steady-state trigger angle on the inverter side.

[0015] Further, the step of configuring the integration duration of the rectifier side trigger angle limiter according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate includes:

[0016] Adjust the preset target angle movement duration according to the steady-state trigger angle on the rectifier side and the DC current change rate to obtain the second integration duration, and configure the second integration duration in the corresponding rectifier side trigger angle limiter.

[0017] Further, the second integration duration is expressed as:

[0018]

[0019] In the formula, represents the second integration duration; represents the preset target angle movement duration; represents a constant coefficient; represents the DC current change rate; represents the steady-state trigger angle on the rectifier side.

[0020] Further, the method further includes:

[0021] The inverter station periodically monitors the path communication delays of different communication paths between it and the rectifier station, obtains the minimum path communication delay within the monitoring period, switches the current inter-station communication path to the communication path corresponding to the minimum path communication delay, and updates the inter-station communication delay record according to the minimum path communication delay.

[0022] Further, the step of the inverter station periodically monitoring the path communication delays of different communication paths between it and the rectifier station and obtaining the minimum path communication delay within the monitoring period includes:

[0023] Periodically generate path detection signals corresponding to each communication path based on a preset time interval, and simultaneously send the path detection signals to the rectifier station through the corresponding communication paths; the path detection signals include path identifiers and transmission times;

[0024] Receive path detection response signals returned by the rectifier station through each communication path, and obtain the corresponding path communication delays according to the reception times and response signal data of the path detection response signals; the response signal data includes the path identifiers and transmission times in the corresponding path detection signals;

[0025] Obtain the minimum path communication delay within the monitoring period according to the minimum value among the path communication delays of all communication paths.

[0026] In a second aspect, an embodiment of the present invention provides a UHV DC online valve group withdrawal system with adaptive trigger angle change, and the system includes:

[0027] An inverter station control module, configured to, in response to a single valve group locking instruction, send a locking execution instruction to the corresponding rectifier station, and configure the integration duration of the trigger angle limiter on the inverter side and the delayed locking execution moment according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay, and execute the locking process on the inverter side when the delayed locking execution moment is reached; the locking process on the inverter side includes adaptively adjusting the trigger angle moving rate based on the integration duration of the trigger angle limiter on the inverter side;

[0028] A rectifier station control module, configured to, when receiving the locking execution instruction, configure the integration duration of the trigger angle limiter on the rectifier side according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate, and immediately execute the locking process on the rectifier side; the locking process on the rectifier side includes adaptively adjusting the trigger angle moving rate based on the integration duration of the trigger angle limiter on the rectifier side.

[0029] Further, the inverter station control module is further configured to periodically monitor the path communication delays of different communication paths with the rectifier station, obtain the minimum path communication delay within the monitoring period, and switch the current inter-station communication path to the communication path corresponding to the minimum path communication delay, and update the inter-station communication delay record according to the minimum path communication delay;

[0030] The rectifier station control module is further configured to receive the path detection signals sent by the inverter station through different communication paths, generate corresponding path detection response signals according to the path detection signals, and send the path detection response signals to the inverter station through the corresponding communication paths.

[0031] Further, the periodic monitoring of the path communication delay between different communication paths between the rectifier station, and obtaining the minimum path communication delay within the monitoring period includes:

[0032] Based on a preset time interval, path detection signals corresponding to each communication path are periodically generated, and the path detection signals are simultaneously sent to the rectifier station through the corresponding communication paths; the path detection signals include path identifiers and transmission times;

[0033] Receiving the path detection response signals returned by the rectifier station through each communication path, and obtaining the corresponding path communication delay according to the reception time and response signal data of the path detection response signals; the response signal data includes the path identifier and transmission time in the corresponding path detection signal;

[0034] According to the minimum value among the path communication delays of all communication paths, the minimum path communication delay within the monitoring period is obtained.

[0035] The present invention provides a method and system for online valve group withdrawal of UHV DC with adaptive trigger angle change. Through the method, in response to a single valve group locking instruction, the inverter station sends a locking execution instruction to the corresponding rectifier station, and configures the integration duration of the trigger angle limiter on the inverter side and delays the locking execution moment according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay. When the delayed locking execution moment is reached, an inverter side locking process including adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the inverter side is executed. And when the rectifier station receives the locking execution instruction, the integration duration of the trigger angle limiter on the rectifier side is configured according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate, and a rectifier side locking process including adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the rectifier side is immediately executed. Compared with the prior art, the method for online valve group withdrawal of UHV DC with adaptive trigger angle change combines the mechanism of aligning the execution moments of the valve group locking instructions on both sides by delaying the trigger angle movement moment on the inverter side based on the inter-station communication delay with the adaptive synchronous trigger angle change mechanism of reasonably configuring the integration duration of the trigger angle limiters on the inverter side and the rectifier side according to the real-time operation conditions of the UHV DC transmission system and the AC system. When actually executing the valve group locking instruction, it can effectively align the starting moments of the angle shifts on the rectifier side and the inverter side and ensure the consistency of the durations for the angle shifts on both sides to reach 90°, realizing the adaptive synchronization of the trigger angle changes on both sides, effectively reducing the disturbance to the DC system caused by valve group withdrawal during operation, and further improving the operation stability of the AC-DC power grid. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the online withdrawal process of the converter in the existing method for online valve group withdrawal of UHV DC;

[0037] Figure 2 It is a schematic flowchart of the method for online valve group withdrawal of UHV DC with adaptive trigger angle change in the embodiments of the present invention;

[0038] Figure 3 It is a schematic flowchart of the online withdrawal process of the converter in the method for online valve group withdrawal of UHV DC with adaptive trigger angle change in the embodiments of the present invention;

[0039] Figure 4 It is a schematic structural diagram of the system for online valve group withdrawal of UHV DC with adaptive trigger angle change in the embodiments of the present invention. Specific embodiments

[0040] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the following described embodiments are part of the embodiments of the present invention, and are only used to illustrate the present invention, but not to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0041] The method for online valve group withdrawal of UHV DC with adaptive trigger angle change provided by the present invention can be understood as an online valve group withdrawal solution that can simultaneously solve the problems of inconsistent execution command times and inconsistent trigger angle change rates on the rectifier side and the inverter side, enabling adaptive synchronization of trigger angle changes on both sides, based on the application status that when the existing UHV online valve group is withdrawn, the DC system is disturbed due to the inconsistent execution command times and inconsistent trigger angle change rates on the rectifier side and the inverter side, resulting in affecting the operation stability of the AC-DC power grid. The following embodiments will describe the method for online valve group withdrawal of UHV DC with adaptive trigger angle change of the present invention in detail.

[0042] In one embodiment, as Figure 2 shown, a method for online valve group withdrawal of UHV DC with adaptive trigger angle change is provided, including the following steps:

[0043] S11. In response to a single valve group blocking instruction, the inverter station sends a blocking execution instruction to the corresponding rectifier station, and configures the integration duration of the trigger angle limiter on the inverter side and the delayed blocking execution time according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay, and executes the blocking process on the inverter side when the delayed blocking execution time is reached; the blocking process on the inverter side includes adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the inverter side; among them, the single valve group blocking instruction can be understood as a single valve group online withdrawal instruction issued by the corresponding control system in the UHV DC transmission system based on the actual system operation conditions, which will not be elaborated here.

[0044] In Figure 1 In the actual converter online withdrawal process shown, when the inverter station receives a single valve group blocking command and starts to execute, it will simultaneously send a message to the rectifier station indicating that it has executed the blocking. Then, after the rectifier station confirms that the opposite station has executed the blocking, it will start to execute the blocking process of its own station. Considering that there will inevitably be communication delays in the inter-station communication between the inverter station and the rectifier station during the actual system operation, the starting time of the rectifier station's blocking process deviates greatly from the starting time of the inverter station's blocking process, which will cause a large difference in the trigger angle movement between the two stations when the two sides execute the blocking process, and further cause a large disturbance to the DC voltage and DC current. To align the starting times of the blocking commands executed by the two stations as much as possible, in this embodiment, it is preferably set to delay the starting time of the inverter station's blocking process based on the monitored communication delay between the inverter station and the rectifier station. At the same time, considering that the steady-state trigger angles on both sides of the rectifier station and the inverter station are not the same in the actual system operation, if the same ALPHA_90 execution rate is directly set on both sides, the time for the actual shift angle to reach 90° on both sides may also be inconsistent. To ensure that the time for the actual shift angle to reach 90° on both sides is as consistent as possible when the rectifier station and the inverter station start to execute the blocking process simultaneously, in this embodiment, based on considering the interaction between the actual UHVDC transmission system and the AC system, the integration duration of the trigger angle limiter on the inverter station side is preferably optimized to limit the total duration for the inverter station to shift from the current steady-state trigger angle to the trigger angle target value of 90°.

[0045] In this embodiment, the steady-state trigger angle on the inverter side can be understood as the trigger angle value when the inverter station is operating when it receives a single valve group blocking command; the corresponding AC voltage volatility and AC frequency deviation can be understood as the voltage fluctuation situation and frequency deviation situation in the AC system interacting with the UHVDC transmission system. The specific data can be obtained by measuring and analyzing through the deployment of corresponding measuring devices or based on the relevant data collected in the existing monitoring system, and no specific limitation is made here. The corresponding inter-station communication delay can be understood as the one-way round-trip communication duration between the inverter station and the rectifier station, and can be obtained by configuring the corresponding communication delay detection logic at the inverter end. Specifically, the steps of configuring the integration duration of the trigger angle limiter on the inverter side and delaying the blocking execution time according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay include:

[0046] Adjust the preset target angle movement duration according to the steady-state trigger angle on the inverter side, the AC voltage volatility, and the AC frequency deviation to obtain a first integration duration, and configure the first integration duration as the integration time constant for the corresponding trigger angle limiter on the inverter side; where the preset target angle movement duration can be understood as the expected time set in advance according to actual application requirements to move from the stable trigger angle to 90°, which is not specifically limited here.

[0047] Considering that in actual applications, voltage fluctuations in the AC system will cause fluctuations in the power transmitted by the DC system and deviations in the AC system frequency will cause deviations in the output of the drive machinery, which will in turn affect the stable operation of the DC system. To maintain the stability of the coordinated operation of the AC-DC power grid, in this embodiment, preferably, when performing the trigger angle movement, the influence of the AC voltage volatility and the AC frequency deviation on the trigger angle adjustment is considered synchronously to determine the expected execution duration for the inverter side to move from the stable trigger angle to 90°, so that the trigger angle adjustment on the inverter side is more accurate and reliable; specifically, the first integration duration is expressed as:

[0048]

[0049] In the formula, represents the first integration duration; represents the preset target angle movement duration, which can be set according to actual application requirements; and represent constant coefficients, which can be set according to actual application requirements and are not specifically limited here; and represent the AC voltage volatility and the AC frequency deviation respectively.

[0050] In this embodiment, considering the close interaction between the UHVDC transmission system and the AC system, the integration time constant value of the trigger angle limiter on the inverter side is designed based on the adjustment method of the preset target angle movement duration according to the actual steady-state trigger angle. It can not only reasonably control the movement duration of the trigger angle of the inverter station based on the preset target angle movement duration, but also take into account maintaining the stable operation and power output of the AC-DC power grid.

[0051] Obtain the delayed blocking execution moment according to the sum of the inter-station communication delay and the receiving moment corresponding to the single valve group blocking instruction; that is, as shown in Figure 3 , the moment obtained by delaying the corresponding duration of the inter-station communication delay based on the receiving moment corresponding to the single valve group blocking instruction is used as the execution moment for the inverter side to start the inverter side blocking process.

[0052] S12. When the rectifier station receives the blocking execution instruction, it configures the integration duration of the rectifier side trigger angle limiter according to the obtained rectifier side steady-state trigger angle and DC current change rate, and immediately executes the rectifier side blocking process; the rectifier side blocking process includes adaptively adjusting the trigger angle movement rate based on the integration duration of the rectifier side trigger angle limiter.

[0053] As Figure 1 shown, after the rectifier station side receives the message that the inverter station side has executed blocking, it will start to execute the blocking process of this station. In order to ensure as much as possible that the time for the actual shift angle of the inverter station side to reach 90° is consistent, in this embodiment, preferably, based on considering the actual operating state of the UHV DC transmission system, the integration duration of the trigger angle limiter on the inverter station side is optimized and set to limit the total duration for the rectifier station to move from the current steady-state trigger angle to the trigger angle target value of 90°.

[0054] In this embodiment, the rectifier side steady-state trigger angle can be understood as the trigger angle value when the rectifier station is operating when receiving the single valve group blocking instruction; the corresponding DC current change rate can be understood as the DC current change situation of the UHV DC transmission system. The specific data can also be obtained by measuring and analyzing through arranging corresponding measuring devices or based on the relevant data collected in the existing monitoring system, and no specific limitation is made here. Specifically, the step of configuring the integration duration of the rectifier side trigger angle limiter according to the obtained rectifier side steady-state trigger angle and DC current change rate includes:

[0055] Adjust the preset target angle movement duration according to the rectifier side steady-state trigger angle and the DC current change rate to obtain the second integration duration, and configure the second integration duration for the corresponding rectifier side trigger angle limiter; among them, the preset target angle movement duration can be understood as the expected time set in advance according to the actual application requirements to move from the stable trigger angle to 90°, and it needs to be consistent with the preset target angle movement duration used on the inverter side.

[0056] Considering that in actual applications, the DC current change rate directly reflects whether the operation state of the UHV DC transmission system is stable. For example, when the DC current change rate is large, it is necessary to appropriately increase the trigger angle adjustment rate to reach the system stable state faster. In order to maintain the stable operation and power output of the DC system, in this embodiment, preferably, when executing the trigger angle movement, the influence of the DC current change rate on the trigger angle adjustment is considered synchronously to determine the expected execution duration for the rectifier side to move from the stable trigger angle to 90°, so that the trigger angle adjustment on the rectifier side is more accurate and reliable; specifically, the second integration duration is expressed as:

[0057]

[0058] In the formula, Indicates the second integration duration; Indicates the preset target angle movement duration; Indicates a constant coefficient; Indicates the DC current change rate; Indicates the rectifier side steady-state trigger angle.

[0059] In this embodiment, considering the operating state of the UHV DC transmission system, the integral time constant value of the rectifier side trigger angle limiter is designed based on the adjustment method of the preset target angle movement duration according to the actual steady-state trigger angle. It can not only reasonably control the trigger angle movement duration of the inverter station based on the preset target angle movement duration, but also take into account the stable and reliable operation of the DC system.

[0060] The embodiment of the present invention provides that in response to a single valve group blocking instruction, the inverter station sends a blocking execution instruction to the corresponding rectifier station, and configures the integral duration of the inverter side trigger angle limiter and the delayed blocking execution moment according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication delay. When the delayed blocking execution moment arrives, it executes the inverter side blocking process including adaptively adjusting the trigger angle movement rate based on the integral duration of the inverter side trigger angle limiter, and when the rectifier station receives the blocking execution instruction, it configures the integral duration of the rectifier side trigger angle limiter according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate, and immediately executes the rectifier side blocking process including adaptively adjusting the trigger angle movement rate based on the integral duration of the rectifier side trigger angle limiter. The technical solution can effectively solve the problems of inconsistent execution command moments and inconsistent trigger angle change rates on the rectifier side and the inverter side during the online valve group withdrawal of the existing UHV, ensure the consistency of the start and end moments of executing the ALPHA_90 instruction on the rectifier side and the inverter side, reduce the disturbance to the DC system caused by the valve group withdrawal during operation, and effectively improve the operation stability of the AC-DC power grid.

[0061] In principle, the method for the inverter station to detect the inter-station communication delay can be implemented by using relevant existing technologies. However, considering that the redundant communication loop mechanism between the inverter station and the rectifier station only implements the communication fault protection strategy of switching to the standby path when the primary communication path fails, in practical applications, there may be a problem that the transmission and execution efficiency of the valve group blocking instruction is reduced due to the large communication delay of the in-use communication path. In order to ensure the effective alignment of the start and end times of the trigger angle shift to 90° instruction execution on the rectifier side and the inverter side, and at the same time effectively improve the execution efficiency of the valve group withdrawal, this embodiment preferably adopts a multi-path fusion delay detection and path switching mechanism on the inverter station side. Redundant communication paths including optical fiber, microwave, and power line carrier can be used between the inverter station and the rectifier station. Each communication device on both sides configures corresponding communication parameters (such as bandwidth, frequency, modulation method, etc.), priorities, and corresponding hardware communication interfaces for each communication path, and is equipped with multiple independent signal processing modules such as corresponding optical fiber interface modules, microwave transceiver modules, and power line carrier communication modules that can implement functions such as signal modulation, demodulation, encoding, and decoding without interfering with each other. And based on the fact that the communication delays of different communication paths in the actual application scenario are different, the path with the smallest communication delay is selected as the instruction transmission path to improve the communication efficiency in practical applications as much as possible. Specifically, the method further includes:

[0062] The inverter station periodically monitors the path communication delays of different communication paths between it and the rectifier station, obtains the minimum path communication delay within the monitoring period, and switches the current inter-station communication path to the communication path corresponding to the minimum path communication delay, and updates the inter-station communication delay record according to the minimum path communication delay; among them, the period for the inverter station to monitor the path communication delays of each communication path between it and the rectifier station can be set based on the stability of each communication path in practical applications. For example, for relatively stable situations, a longer time can be set to trigger the delay monitoring once, and vice versa, a shorter time can be set to trigger the monitoring once. The minimum path communication delay obtained by monitoring each period can be used as both the condition for the inverter station to select the optimal communication path and switch the communication path between it and the rectifier station, and as the basis for setting the delayed blocking execution time when it receives the single valve group blocking instruction.

[0063] To ensure the reliability of obtaining the minimum path communication delay and the optimal communication path between the inverter station and the rectifier station, this embodiment preferably sets a unique path identifier for each communication path on the inverter station side. The path identifier can be set as an encoding sequence including a timestamp, a random number, and a communication protocol. In practical applications, corresponding path identifiers can be generated for each communication path based on technologies such as programmable logic devices (such as FPGA) that can implement this function, so as to facilitate accurate statistical analysis of the communication delays of different communication paths; specifically, the step of the inverter station periodically monitoring the path communication delays of different communication paths between it and the rectifier station and obtaining the minimum path communication delay within the monitoring period includes:

[0064] Periodically generate path detection signals corresponding to each communication path based on a preset time interval, and simultaneously send the path detection signals to the rectifier station through the corresponding communication paths; the path detection signals include path identifiers and transmission times, and other information can also be added according to actual application requirements; in actual applications, the path identifiers in the path detection signals can be generated by calling the corresponding path identifier generation module (such as a hardware circuit) to generate unique identifiers and embed them into the corresponding detection signals, and then modulate and encode the signals based on application requirements to adapt to the transmission requirements of the corresponding communication paths. For example, for fiber optic communication paths, optical modulation technology is used to load the signal onto an optical carrier, and for microwave communication paths, radio frequency modulation is performed, etc.

[0065] Receive the path detection response signals returned by the rectifier station through each communication path, and obtain the corresponding path communication delay according to the reception time and response signal data of the path detection response signals; among them, the path detection response signal can be understood as the response signal generated by the rectifier station after receiving the path detection signals sent by the inverter station through each communication path and parsing and identifying the content of the path detection signals; the corresponding response signal data can include the path identifier and transmission time in the corresponding path detection signal, and can also include other data contents set according to application requirements. In actual applications, after the inverter station receives the path detection response signals returned by the rectifier station through each communication path, the corresponding response signal data can be obtained through demodulation and decoding analysis of each path detection response signal, and then the communication delay of the current detection cycle of the communication path corresponding to the path identifier can be obtained based on the difference between the reception time of the path detection response signal and the transmission time of the path detection signal in the response signal data. It should be noted that the inverter station side can be equipped with high-precision time recording hardware at each communication interface, such as a timer chip based on a quartz crystal oscillator (with a precision up to the nanosecond level), to record the time at the moment of receiving the signal, and make each timer synchronized with the system clock through a hardware clock synchronization mechanism to ensure the accuracy and comparability of the communication delay statistics of each communication path.

[0066] Obtain the minimum path communication delay within the monitoring period according to the minimum value among the path communication delays of all communication paths.

[0067] In the embodiments of the present invention, a multi-path fusion time-delay detection and path switching mechanism is configured on the inverter station side to periodically monitor the inter-station communication time-delay, so as to switch the communication path between the inverter station and the rectifier station and update the record of the inter-station communication time-delay. After the inverter station receives a single valve group locking instruction, a locking execution instruction is sent to the corresponding rectifier station. According to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication time-delay, the integration duration of the trigger angle limiter on the inverter side and the delayed locking execution moment are configured. When the delayed locking execution moment is reached, an inverter-side locking process is executed, including an inverter-side locking process that adaptively adjusts the trigger angle movement rate based on the integration duration of the trigger angle limiter on the inverter side. When the rectifier station receives the locking execution instruction, according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate, the integration duration of the trigger angle limiter on the rectifier side is configured, and a rectifier-side locking process including an adaptive adjustment of the trigger angle movement rate based on the integration duration of the trigger angle limiter on the rectifier side is immediately executed. This solution can not only ensure the consistency of the start and end moments of executing the ALPHA_90 instruction on the rectifier side and the inverter side, reduce the disturbance to the DC system caused by valve group withdrawal during operation, effectively improve the operation stability of the AC-DC power grid, but also effectively improve the execution efficiency of online valve group withdrawal.

[0068] It should be noted that although the steps in the above flowcharts are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders.

[0069] In one embodiment, as Figure 4 shown, a UHV DC online valve group withdrawal system with adaptive trigger angle change is provided. The system includes:

[0070] An inverter station control module 1, which is used to respond to a single valve group locking instruction, send a locking execution instruction to the corresponding rectifier station, configure the integration duration of the trigger angle limiter on the inverter side and the delayed locking execution moment according to the obtained steady-state trigger angle on the inverter side, AC voltage volatility, AC frequency deviation, and inter-station communication time-delay, and execute an inverter-side locking process when the delayed locking execution moment is reached; the inverter-side locking process includes adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the inverter side;

[0071] A rectifier station control module 2, which is used to configure the integration duration of the trigger angle limiter on the rectifier side according to the obtained steady-state trigger angle on the rectifier side and the DC current change rate when receiving the locking execution instruction, and immediately execute a rectifier-side locking process; the rectifier-side locking process includes adaptively adjusting the trigger angle movement rate based on the integration duration of the trigger angle limiter on the rectifier side.

[0072] In one embodiment, the inverter station control module 1 is further configured to periodically monitor the path communication delays of different communication paths between the inverter station and the rectifier station, obtain the minimum path communication delay within the monitoring period, switch the current inter-station communication path to the communication path corresponding to the minimum path communication delay, and update the inter-station communication delay record according to the minimum path communication delay.

[0073] Specifically, the steps for the inverter station to periodically monitor the path communication delays of different communication paths between the inverter station and the rectifier station and obtain the minimum path communication delay within the monitoring period include:

[0074] Periodically generate path detection signals corresponding to each communication path based on a preset time interval, and simultaneously send the path detection signals to the rectifier station through the corresponding communication paths; the path detection signals include path identifiers and sending times;

[0075] Receive the path detection response signals returned by the rectifier station through each communication path, and obtain the corresponding path communication delays according to the reception times and response signal data of the path detection response signals; the response signal data includes the path identifiers and sending times in the corresponding path detection signals;

[0076] Obtain the minimum path communication delay within the monitoring period according to the minimum value among the path communication delays of all communication paths.

[0077] The rectifier station control module 2 is further configured to receive the path detection signals sent by the inverter station through different communication paths, generate corresponding path detection response signals according to the path detection signals, and send the path detection response signals to the inverter station through the corresponding communication paths.

[0078] For the specific limitations of the UHV DC online valve group withdrawal system regarding the adaptive trigger angle change, reference can be made to the limitations of the UHV DC online valve group withdrawal method for the adaptive trigger angle change in the above text, and the corresponding technical effects can also be equivalently obtained, which will not be elaborated here. Each module in the above UHV DC online valve group withdrawal system regarding the adaptive trigger angle change can be implemented in whole or in part through software, hardware, and their combinations. The above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above respective modules.

[0079] In summary, the UHVDC online valve group withdrawal method and system with adaptive trigger angle change provided by the embodiments of the present invention. The UHVDC online valve group withdrawal method with adaptive trigger angle change periodically monitors the inter-station communication delay by configuring a multi-path fusion delay detection and path switching mechanism on the inverter station side to switch the communication path between the inverter station and the rectifier station and update the record of the inter-station communication delay. It combines the alignment mechanism of the execution times of the valve group locking instructions on both sides that delays the trigger angle shift moment on the inverter side based on the inter-station communication delay with the adaptive synchronous trigger angle change mechanism that adaptively and reasonably configures the integration duration of the trigger angle limiters on the inverter side and the rectifier side based on the real-time operating conditions of the UHVDC transmission system and the AC system. When actually executing the valve group locking instruction, it can effectively align the starting moments of the angle shift on the rectifier side and the inverter side and ensure the consistency of the duration for both sides to shift the angle to 90°, realizing the adaptive synchronization of the trigger angle changes on both sides, effectively reducing the disturbance to the DC system caused by withdrawing the valve group during operation, improving the operation stability of the AC-DC power grid, and at the same time, effectively improving the execution efficiency of the online valve group withdrawal.

[0080] Each embodiment in this specification is described in a progressive manner. For parts that are the same or similar in each embodiment, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and reference can be made to the partial description of the method embodiment for the relevant parts. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0081] The above-described embodiments only represent several preferred implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and substitutions can still be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the protection scope of the claims.

Claims

1. A method for online valve group withdrawal of ultra-high voltage direct current with adaptive trigger angle change, characterized in that: The method comprises the following steps: In response to the single valve group locking instruction, the inverter station sends a locking execution instruction to the corresponding rectifier station, and configures the inverter side trigger angle limiter integration time and the delayed locking execution time according to the acquired inverter side steady-state trigger angle, AC voltage fluctuation rate, AC frequency deviation and inter-station communication delay, and executes the inverter side locking process when the delayed locking execution time is reached; the inverter side locking process includes adaptively adjusting the trigger angle movement rate based on the inverter side trigger angle limiter integration time; When the rectifier station receives the locking execution instruction, it configures the integral time of the trigger angle limiter on the rectifier side according to the acquired steady-state trigger angle and DC current change rate on the rectifier side, and immediately executes the locking process on the rectifier side; the locking process on the rectifier side includes adaptively adjusting the trigger angle movement rate based on the integral time of the trigger angle limiter on the rectifier side; The step of configuring the inverter side trigger angle limiter integration time and delayed locking execution time according to the acquired inverter side steady-state trigger angle, AC voltage fluctuation rate, AC frequency deviation and inter-station communication delay includes: According to the inverter-side steady-state trigger angle, the AC voltage fluctuation rate and the AC frequency deviation, the preset target angle movement time is adjusted to obtain a first integration time, and the first integration time is configured as an integration time constant in the corresponding inverter-side trigger angle limiter; The delayed locking execution time is obtained according to the sum of the inter-station communication delay and the receiving time corresponding to the single valve group locking instruction.

2. The method for online valve group withdrawal of UHV DC with adaptive trigger angle change according to claim 1, characterized in that: The first integration duration is expressed as: In the formula, Indicates the duration of the first integral; Indicates the duration of the preset target angle movement; and represents a constant coefficient; and They represent the AC voltage fluctuation rate and AC frequency deviation respectively; Indicates the steady-state trigger angle of the inverter side.

3. The method for online valve group withdrawal of ultra-high voltage direct current with adaptive trigger angle change according to claim 1, characterized in that: The step of configuring the integral time length of the rectifier side trigger angle limiter according to the acquired rectifier side steady-state trigger angle and DC current change rate comprises: According to the rectifier-side steady-state trigger angle and the DC current change rate, the preset target angle movement duration is adjusted to obtain a second integration duration, and the second integration duration is configured at the corresponding rectifier-side trigger angle limiter.

4. The method for online valve group withdrawal of ultra-high voltage direct current with adaptive trigger angle change according to claim 3 is characterized in that: The second integral duration is expressed as: In the formula, Indicates the duration of the second integral; Indicates the duration of the preset target angle movement; represents a constant coefficient; Indicates the rate of change of DC current; Indicates the steady-state firing angle on the rectifier side.

5. The method for online valve group withdrawal of UHV DC with adaptive trigger angle change according to claim 1, characterized in that: The method further comprises: The inverter station periodically monitors the path communication delays of different communication paths with the rectifier station, obtains the minimum path communication delay within the monitoring period, switches the current inter-station communication path to the communication path corresponding to the minimum path communication delay, and updates the inter-station communication delay record according to the minimum path communication delay.

6. The method for online valve group withdrawal of UHV DC with adaptive trigger angle change according to claim 5, characterized in that: The inverter station periodically monitors the path communication delays of different communication paths between the inverter station and the rectifier station, and the step of obtaining the minimum path communication delay within the monitoring period includes: Periodically generate a path detection signal corresponding to each communication path based on a preset time interval, and simultaneously send the path detection signal to the rectifier station through the corresponding communication path; the path detection signal includes a path identifier and a sending time; Receiving the path detection response signal returned by the rectifier station through each communication path, and obtaining the corresponding path communication delay according to the receiving time of the path detection response signal and the response signal data; the response signal data includes the path identifier and the sending time in the corresponding path detection signal; According to the minimum value of the path communication delays of all communication paths, the minimum path communication delay within the monitoring period is obtained.

7. An ultra-high voltage direct current online valve group withdrawal system with adaptive trigger angle change, using the ultra-high voltage direct current online valve group withdrawal method with adaptive trigger angle change as claimed in claim 1, characterized in that: The system comprises: The inverter station control module is used to respond to the single valve group locking instruction, send a locking execution instruction to the corresponding rectifier station, and configure the inverter side trigger angle limiter integration time and delayed locking execution time according to the acquired inverter side steady-state trigger angle, AC voltage fluctuation rate, AC frequency deviation and inter-station communication delay, and execute the inverter side locking process when the delayed locking execution time is reached; the inverter side locking process includes adaptively adjusting the trigger angle movement rate based on the inverter side trigger angle limiter integration time; The rectifier station control module is used to configure the integration time of the rectifier side trigger angle limiter according to the acquired steady-state trigger angle and DC current change rate of the rectifier side when receiving the lockout execution instruction, and immediately execute the rectifier side lockout process; the rectifier side lockout process includes adaptively adjusting the trigger angle movement rate based on the integration time of the rectifier side trigger angle limiter.

8. The UHV DC online valve withdrawal system with adaptive trigger angle change according to claim 7, characterized in that: The inverter station control module is further used to periodically monitor the path communication delays of different communication paths between the rectifier stations, obtain the minimum path communication delay within the monitoring period, switch the current inter-station communication path to the communication path corresponding to the minimum path communication delay, and update the inter-station communication delay record according to the minimum path communication delay; The rectifier station control module is also used to receive the path detection signal sent by the inverter station through different communication paths, generate a corresponding path detection response signal according to the path detection signal, and send the path detection response signal to the inverter station through the corresponding communication path.

9. The UHV DC online valve withdrawal system with adaptive trigger angle change according to claim 8, characterized in that: The periodic monitoring of the path communication delays of different communication paths between the rectifier stations to obtain the minimum path communication delay within the monitoring period includes: Periodically generate a path detection signal corresponding to each communication path based on a preset time interval, and simultaneously send the path detection signal to the rectifier station through the corresponding communication path; the path detection signal includes a path identifier and a sending time; Receiving the path detection response signal returned by the rectifier station through each communication path, and obtaining the corresponding path communication delay according to the receiving time of the path detection response signal and the response signal data; the response signal data includes the path identifier and the sending time in the corresponding path detection signal; According to the minimum value of the path communication delays of all communication paths, the minimum path communication delay within the monitoring period is obtained.

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