Method, device and equipment for suppressing commutation failure control of hybrid phase commutated converter

Abstract

The application relates to the technical field of control of a hybrid commutation converter, and provides a commutation failure suppression control method, device and equipment for the hybrid commutation converter, which comprises the following steps: acquiring a fault mode of a large-scale new energy direct-current transmission system, and a valve trigger pulse signal, a valve current and a trigger angle of the hybrid commutation converter; determining a commutation failure suppression control strategy according to the fault mode; if the commutation failure suppression control strategy is a forced shutdown mode, determining a first forced shutdown signal according to the valve trigger pulse signal and the valve current; determining a delay time according to the trigger angle; determining a second forced shutdown signal according to the delay time and the valve trigger pulse signal; determining a forced shutdown signal of the forced shutdown mode according to the first forced shutdown signal and the second forced shutdown signal; and controlling the hybrid commutation converter to perform commutation operation according to the forced shutdown signal. The method adaptively adjusts the forced shutdown signal of the hybrid commutation converter, so that better commutation failure resistance can be realized.

Description

Technical Field

[0001] This application relates to the field of control technology for hybrid commutator converters, and more particularly to a method, apparatus, and device for controlling commutation failure suppression in a hybrid commutator converter. Background Technology

[0002] In recent years, large-scale new energy sources have been greatly developed. Large-scale new energy bases are mainly distributed in sparsely populated areas, located at the end of the AC main grid. The power grids in sparsely populated areas are weak and lack the support of large power grids. Therefore, the energy from large-scale new energy bases needs to be transmitted over long distances.

[0003] Hybrid commutated converters (HCCs) are a new type of converter that has attracted much attention in high-voltage, long-distance DC power transmission systems. HCC technology utilizes reverse-resistance integrated gate commutation thyristors (IGCTs). As a converter element, the blocking-IGCT (RB-IGCT) features bidirectional voltage withstand capability, unidirectional current conduction, a monolithic device structure, and long-term short-circuit failure mode, similar to thyristors. It also possesses the ability to actively interrupt current. Compared to conventional IGBTs, the blocking-IGCT has higher surge current withstand capability and lower losses. The hybrid commutation converter (HCC) retains the basic topology of the grid commutation converter LCC thyristor converter valve, directly replacing the thyristors in the original grid commutation converter LCC converter valve with blocking-IGCT devices. This creates a converter with controllable active turn-off capability, offering advantages such as resistance to commutation failure, simple topology, low reactive power absorption, moderate cost, and low losses.

[0004] During a fault on the AC side of a large-scale renewable energy transmission system via DC, considering the use of a hybrid commutator converter (HCC) at the receiving end, the forced shutdown function of the HCC is a crucial valve control strategy to ensure successful fault ride-through and commutation failure mitigation. However, existing HCC forced shutdown valve control systems all use a constant delay for the delayed shutdown portion. There is no standard for selecting this constant delay under different power transmission projects, main circuit parameters, and boundary conditions. Furthermore, if the constant delay is too large, the converter valve in the large-scale renewable energy transmission system via DC may not shut off in time, making it unable to withstand commutation failure. Summary of the Invention

[0005] This application provides a method, apparatus, and equipment for suppressing commutation failure in a hybrid commutation converter, which addresses the technical problem of untimely shutdown leading to commutation failure in existing hybrid commutation converters used in large-scale new energy DC transmission systems.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] On the one hand, a method for suppressing commutation failure control in a hybrid commutator is provided, which is applied to a large-scale new energy transmission system via DC. This method for suppressing commutation failure control includes the following steps:

[0008] The fault modes of the large-scale new energy DC transmission system are obtained, as well as the valve trigger pulse signal, valve current and trigger angle of the hybrid commutation converter;

[0009] Based on the aforementioned failure modes, a commutation failure suppression control strategy for the hybrid commutation converter is determined.

[0010] If the commutation failure suppression control strategy is a forced shutdown mode, a first forced shutdown signal is determined based on the valve trigger pulse signal and the valve current; a delay time is determined based on the trigger angle; a second forced shutdown signal is determined based on the delay time and the valve trigger pulse signal; and a forced shutdown signal for the forced shutdown mode is determined based on the first forced shutdown signal and the second forced shutdown signal.

[0011] The hybrid commutator is controlled to perform commutation operation according to the forced shutdown signal.

[0012] Optionally, determining the delay time based on the trigger angle includes:

[0013] Obtain the preset trigger angle and preset commutation delay time of the hybrid commutator;

[0014] The commutation delay coefficient of the hybrid commutator is determined based on the preset trigger angle and the trigger angle.

[0015] The delay time of the hybrid commutation converter is calculated based on the commutation delay coefficient and the preset commutation delay time.

[0016] Optionally, determining the second forced shutdown signal based on the delay time and the valve trigger pulse signal includes:

[0017] The valve trigger pulse signal is subjected to logical NOT processing to obtain a processed signal;

[0018] The processing signal is delayed according to the delay time to obtain a second forced shutdown signal.

[0019] Optionally, based on the failure mode, the strategy for suppressing commutation failure of the hybrid commutator includes:

[0020] If the fault mode is a single-phase grounding fault on the AC side of the receiving end of the large-scale new energy transmission system via DC, then the commutation failure suppression control strategy is the commutation enhancement mode.

[0021] If the fault mode is a three-phase grounding fault on the receiving end AC side of the large-scale new energy transmission system via DC, then the commutation failure suppression control strategy is a forced shutdown mode.

[0022] Optionally, the method for suppressing commutation failure control of the hybrid commutation converter further includes: if the commutation failure suppression control strategy is a commutation enhancement mode, determining a commutation enhancement signal based on the valve trigger pulse signal and the valve current; and controlling the hybrid commutation converter to perform commutation operation based on the commutation enhancement signal.

[0023] On the other hand, a commutation failure suppression control device for a hybrid commutator is provided, which is applied to a large-scale new energy DC transmission system. The commutation failure suppression control device includes: a data acquisition module, a control strategy determination module, a signal determination module, and an execution module.

[0024] The data acquisition module is used to acquire the fault mode of the large-scale new energy DC transmission system, as well as the valve trigger pulse signal, valve current and trigger angle of the hybrid commutation converter;

[0025] The control strategy determination module is used to determine the commutation failure suppression control strategy of the hybrid commutation converter according to the fault mode.

[0026] The signal determination module is used to determine a first forced shutdown signal based on the valve trigger pulse signal and the valve current, according to the forced shutdown mode of the commutation failure suppression control strategy; determine a delay time based on the trigger angle; determine a second forced shutdown signal based on the delay time and the valve trigger pulse signal; and determine the forced shutdown signal of the forced shutdown mode based on the first forced shutdown signal and the second forced shutdown signal.

[0027] The execution module is used to control the hybrid commutator to perform commutation operation according to the forced shutdown signal.

[0028] Optionally, the signal determination module includes a delay submodule, which is used to obtain the trigger preset angle and preset commutation delay time of the hybrid commutation converter; determine the commutation delay coefficient of the hybrid commutation converter according to the trigger preset angle and the trigger angle; and calculate the delay time of the hybrid commutation converter according to the commutation delay coefficient and the preset commutation delay time.

[0029] Optionally, the signal determination module further includes a signal determination submodule; the signal determination submodule is used to perform logical NOT processing on the valve trigger pulse signal to obtain a processed signal; and to perform delay processing on the processed signal according to the delay time to obtain a second forced shutdown signal.

[0030] Optionally, the control strategy determination module is further configured to, if the fault mode is a single-phase ground fault on the receiving end AC side of the large-scale new energy transmission system via DC transmission, then the commutation failure suppression control strategy is a commutation enhancement mode; or if the fault mode is a three-phase ground fault on the receiving end AC side of the large-scale new energy transmission system via DC transmission, then the commutation failure suppression control strategy is a forced shutdown mode.

[0031] On the other hand, a terminal device is provided, including a processor and a memory;

[0032] The memory is used to store program code and transmit the program code to the processor;

[0033] The processor is configured to execute the above-described method for suppressing commutation failure control of a hybrid commutator according to instructions in the program code.

[0034] The present invention discloses a method, apparatus, and device for suppressing commutation failure control in a hybrid commutation converter. The method includes acquiring a fault mode of a large-scale renewable energy transmission system via DC transmission, as well as the valve trigger pulse signal, valve current, and trigger angle of the hybrid commutation converter; determining a commutation failure suppression control strategy based on the fault mode; if the commutation failure suppression control strategy is a forced shutdown mode, determining a first forced shutdown signal based on the valve trigger pulse signal and valve current; determining a delay time based on the trigger angle; determining a second forced shutdown signal based on the delay time and the valve trigger pulse signal; determining a forced shutdown signal for the forced shutdown mode based on the first and second forced shutdown signals; and controlling the hybrid commutation converter to perform a commutation operation based on the forced shutdown signal.

[0035] As can be seen from the above technical solutions, this application has the following advantages: The method for suppressing commutation failure in the hybrid commutation converter determines the delay time based on the trigger angle when the commutation failure suppression control strategy is in forced turn-off mode, and obtains the forced turn-off signal based on the delay time. This enables large-scale new energy to achieve three-phase fault ride-through on the AC side of the receiving end through the DC transmission system. At the same time, it adaptively adjusts the forced turn-off signal of the reverse-resistance type RB-IGCT device in the hybrid commutation converter to achieve better commutation failure resistance and avoid the inability of the reverse-resistance type RB-IGCT device in the hybrid commutation converter to turn off, resulting in commutation failure. This solves the technical problem that the existing hybrid commutation converter suppression method for large-scale new energy through DC transmission systems has untimely turn-off, leading to commutation failure.

[0036] The commutation failure suppression control device of this hybrid commutator determines the commutation failure suppression control strategy to be in forced shutdown mode through a data acquisition module, a control strategy determination module, a signal determination module, and an execution module. It determines the delay time based on the trigger angle and obtains the forced shutdown signal based on the delay time. This enables large-scale new energy to achieve three-phase fault ride-through on the AC side of the receiving end through the DC transmission system. At the same time, it adaptively adjusts the forced shutdown signal of the reverse-resistance type RB-IGCT device in the hybrid commutator to achieve better commutation failure resistance and avoid the inability of the reverse-resistance type RB-IGCT device in the hybrid commutator to turn off, which would lead to commutation failure. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0038] Figure 1 This is a flowchart illustrating the steps of the method for suppressing commutation failure control in a hybrid commutator as described in an embodiment of this application.

[0039] Figure 2 This is a topology diagram of a large-scale new energy transmission system via DC in the method for suppressing commutation failure control of a hybrid commutator described in the embodiments of this application.

[0040] Figure 3 This is a schematic diagram of the framework for obtaining the first forced turn-off signal in the method for suppressing commutation failure control of a hybrid commutator according to an embodiment of this application;

[0041] Figure 4 This is a schematic diagram of the framework for obtaining the second forced turn-off signal in the method for suppressing commutation failure control of a hybrid commutator according to an embodiment of this application;

[0042] Figure 5 This is a schematic diagram illustrating the framework for obtaining the forced turn-off signal in the method for suppressing commutation failure control of a hybrid commutator as described in the embodiments of this application.

[0043] Figure 6 This is a schematic diagram illustrating the framework for obtaining the delay time in the method for suppressing commutation failure control of a hybrid commutator as described in the embodiments of this application.

[0044] Figure 7 This is a schematic diagram of the commutation enhancement mode in the commutation failure suppression control method of the hybrid commutation converter described in the embodiments of this application;

[0045] Figure 8 This is a schematic diagram showing the variation curves of the firing angle and delay time of a three-phase AC side fault under the commutation failure suppression control method of the hybrid commutator described in the embodiments of this application.

[0046] Figure 9 This is a schematic diagram of the signal curve of the three-phase AC side fault forced shutdown mode under the commutation failure suppression control method of the hybrid commutator described in the embodiments of this application.

[0047] Figure 10 This is a schematic diagram of the valve current curve for a three-phase AC side fault under the method for suppressing commutation failure control of the hybrid commutator described in this application embodiment;

[0048] Figure 11 This is a schematic diagram of the frame of the commutation failure suppression control device for the hybrid commutator described in the embodiments of this application;

[0049] Figure 12 This is a schematic diagram of the terminal device described in an embodiment of this application. Detailed Implementation

[0050] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] In the description of the embodiments of this application, 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. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0052] In the embodiments of this application, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0053] Patent terminology used in this application:

[0054] Grid-forming control, also known as grid-based control, allows distributed energy resources to autonomously establish and maintain grid voltage and frequency through inverters, providing auxiliary services such as inertia support and voltage support to the grid, thereby enhancing grid stability and reliability.

[0055] Constant DC voltage control refers to the DC voltage of the DC system being controlled by the receiving end hybrid commutator HCC. That is, the input of the hybrid commutator HCC is (the actual value of DC voltage and the reference value of DC voltage), and after the difference is calculated, it passes through a PI circuit, and the output of the hybrid commutator HCC is the firing angle α.

[0056] A modular multilevel converter (MMC) is composed of multiple cascaded sub-modules (SMs) with identical structures. The sub-modules can be classified into three types: half-H-bridge, full-H-bridge, and dual-clamped sub-modules.

[0057] This application provides a method, apparatus, and device for suppressing commutation failure in a hybrid commutation converter, which solves the technical problem that existing methods for suppressing commutation failure in hybrid commutation converters of large-scale new energy transmission systems via DC have untimely shutdown, leading to commutation failure.

[0058] Example 1:

[0059] Figure 1 This is a flowchart illustrating the steps of the method for suppressing commutation failure control in a hybrid commutator according to an embodiment of this application. Figure 2 This is a topology diagram of a large-scale new energy transmission system via DC in the method for suppressing commutation failure control of a hybrid commutator described in the embodiments of this application.

[0060] like Figure 2 As shown, this application provides a method for suppressing commutation failure control in a hybrid commutation converter, which is applied to a large-scale new energy DC transmission system. The large-scale new energy DC transmission system includes a new energy power plant, a sending station 101, a DC line, a receiving station 102, and a receiving power grid. The new energy power plant is connected to the sending station 101 via an AC line. The sending station 101 is connected to the DC side of the receiving station 102 via a DC line. The AC side of the receiving station 102 is connected to the receiving power grid.

[0061] It should be noted that, as Figure 2 As shown, the sending station 101 includes a first AC bus connected to an AC line, and a positive sending end MMC and a negative sending end MMC connected to the first AC bus. The receiving station 102 includes a second AC bus connected to the receiving end power grid, and a positive receiving end HCC and a negative receiving end HCC connected to the second AC bus. The first terminal of the DC side of the positive sending end MMC is connected to the first terminal of the DC side of the positive receiving end HCC through a DC circuit. The first terminal of the DC side of the negative sending end MMC is connected to the second terminal of the DC side of the negative receiving end HCC through a DC circuit. The second terminal of the DC side of the positive sending end MMC is connected to the first terminal of the DC side of the negative sending end MMC and then grounded. The second terminal of the DC side of the positive receiving end HCC is connected to the first terminal of the DC side of the negative receiving end HCC and then grounded.

[0062] In this embodiment, the sending-end MMC adopts a grid-type control to construct AC voltage and frequency for the island of the new energy power station, and the receiving-end HCC adopts a constant DC voltage control to output DC current and firing angle α.

[0063] like Figure 1 As shown in the figure, this application provides a method for suppressing commutation failure control in a hybrid commutation converter, including the following steps:

[0064] S1. Obtain the fault modes of a large-scale new energy transmission system via DC transmission, as well as the valve trigger pulse signal, valve current, and trigger angle of the hybrid commutator converter.

[0065] It should be noted that in the process of suppressing commutation failure control of the hybrid commutator, step S1 can obtain the electrical quantity data (such as current, voltage, etc.) of the three phases of the AC side of the large-scale new energy DC transmission system through online monitoring devices, sensors, and information systems. By comparing the collected electrical quantity data with the electrical quantity data of the AC side under normal operation of the large-scale new energy DC transmission system, the fault mode is determined. For example, if the voltage of one phase in the electrical quantity data drops to zero, and the voltage of the other two phases rises to the line voltage (such as 525kV), it indicates that the fault mode of the large-scale new energy DC transmission system is a single-phase ground fault on the AC side of the receiving end; if the voltage of all three phases in the electrical quantity data drops to zero, it indicates that the fault mode of the large-scale new energy DC transmission system is a three-phase ground fault on the AC side of the receiving end. Step S1 can obtain multi-dimensional data such as valve trigger pulse signal, valve current and trigger angle of the hybrid commutator through online monitoring devices, sensors and information systems. This provides the basic data for subsequent steps to obtain the forced turn-off signal that controls the hybrid commutator to successfully perform commutation operation. This enables the large-scale new energy transmission system to achieve fault ride-through on the AC side of the receiving end, and at the same time, adaptively adjust the forced turn-off signal of the reverse-resistance IGCT device in the hybrid commutator to achieve better commutation failure resistance.

[0066] In other embodiments, the method for suppressing commutation failure control of the hybrid commutator can obtain, in step S1, electrical quantity data required to determine the fault mode of a large-scale new energy transmission system via DC transmission, as well as valve trigger pulse signal, valve current, and trigger angle of the hybrid commutator from a power data acquisition system or database.

[0067] S2. Determine the control strategy for suppressing commutation failure in the hybrid commutation converter based on the failure mode.

[0068] It should be noted that step S2 determines the commutation failure suppression control strategy based on the fault mode obtained in step S1, providing data for subsequent steps to select which mode to output the control signal for the hybrid commutation converter in order to successfully suppress commutation failure. In this embodiment, the commutation failure suppression control strategy of the hybrid commutation converter is determined using preset rules based on the fault mode obtained in step S1.

[0069] S3. If the control strategy for suppressing commutation failure is a forced shutdown mode, determine the first forced shutdown signal based on the valve trigger pulse signal and the valve current; determine the delay time based on the trigger angle; determine the second forced shutdown signal based on the delay time and the valve trigger pulse signal; and determine the forced shutdown signal for the forced shutdown mode based on the first forced shutdown signal and the second forced shutdown signal.

[0070] It should be noted that step S3 first involves processing the valve trigger pulse signal, valve current, and trigger angle of the hybrid commutation converter obtained in step S1 according to a preset rule, based on the forced shutdown mode control strategy for suppressing commutation failure determined in step S2. This yields a first forced shutdown signal and a second forced shutdown signal. Then, the forced shutdown signal for the forced shutdown mode is determined from the first and second forced shutdown signals. This provides a signal to control the operation of the hybrid commutation converter, which can successfully suppress commutation failure in the hybrid commutation converter.

[0071] Figure 3 This is a schematic diagram illustrating the framework for obtaining the first forced turn-off signal in the method for suppressing commutation failure control of a hybrid commutator as described in the embodiments of this application.

[0072] like Figure 3 As shown in the embodiments of this application, the preset rule for determining the first forced shutdown signal based on the valve trigger pulse signal and the valve current can be understood as follows:

[0073] The valve current is differentiated to obtain the valve current change rate; the valve current change rate is compared with the current change rate threshold to obtain the first output signal.

[0074] The valve current is compared with the maximum shut-off valve current to obtain the second output signal; the valve trigger pulse signal is logically NOT processed to obtain the third output signal; the second and third output signals are logically ANDed to obtain the fourth output signal.

[0075] The fourth output signal and the first output signal are subjected to a logical AND operation to obtain the first forced shutdown signal.

[0076] It should be noted that the current change rate threshold ratio can be set to 0. If the valve current change rate is greater than the current change rate threshold, the first output signal is 1; if the valve current change rate is not greater than the current change rate threshold, the first output signal is 0. If the valve current is less than the maximum shut-off valve current, the second output signal is 1; if the valve current is not less than the maximum shut-off valve current, the second output signal is 0. In this embodiment, as... Figure 3As shown, when the valve current change rate di / dt is greater than 0, and the enable signal is input to the control terminal of the reverse-resistance RB-IGCT device of the hybrid commutation converter, the first forced shutdown signal outputs an enable signal of 1. Since the commutation failure characteristic of most existing AC system faults is that the commutation current changes from a negative valve current change rate to a positive valve current change rate, when the valve current change rate is detected to change from negative to positive, a commutation failure is determined, and the first forced shutdown signal outputs an enable signal of 1, forcing the reverse-resistance RB-IGCT device of the hybrid commutation converter to turn off. Specifically, when the valve trigger pulse signal of the hybrid commutation converter is 0, and the valve current is less than the maximum turn-off valve current of the device, the hybrid commutation converter is considered to be in active shutdown mode, and the reverse-resistance RB-IGCT device of the hybrid commutation converter can be forcibly shut down.

[0077] Figure 4 This is a schematic diagram illustrating the framework for obtaining the second forced turn-off signal in the method for suppressing commutation failure control of a hybrid commutator as described in the embodiments of this application.

[0078] like Figure 4 As shown, in one embodiment of this application, determining the second forced shutdown signal based on the delay time and the valve trigger pulse signal includes:

[0079] The valve trigger pulse signal is logically NOT processed to obtain the processed signal;

[0080] The signal is delayed based on the delay time to obtain the second forced shutdown signal.

[0081] It should be noted that the preset rule for determining the second forced shutdown signal based on the delay time and the valve trigger pulse signal can be understood as follows: after performing a logical NOT operation on the valve trigger pulse signal, the delay time is applied to obtain the second forced shutdown signal. In this embodiment, during the process of obtaining the second forced shutdown signal, after the valve trigger pulse signal is inverted and delayed by a delay time t, the second forced shutdown signal is set to 1. The second forced shutdown signal is designed for situations where the valve current change rate does not have the characteristic of changing from negative to positive under severe AC faults, so that the hybrid commutation converter issues a forced shutdown signal of 1 after a delay time t from the commutation moment.

[0082] Figure 5 This is a schematic diagram illustrating the framework for obtaining the forced turn-off signal in the method for suppressing commutation failure control of a hybrid commutator as described in the embodiments of this application.

[0083] like Figure 5As shown in the embodiments of this application, the preset rule for determining the forced shutdown signal of the forced shutdown mode based on the first forced shutdown signal and the second forced shutdown signal can be understood as: performing a logical OR operation on the first forced shutdown signal and the second forced shutdown signal to obtain the forced shutdown signal of the forced shutdown mode.

[0084] It should be noted that the forced shutdown mode selects one signal from the first forced shutdown signal and the second forced shutdown signal as the forced shutdown signal to control the hybrid commutation converter to perform forced shutdown, thereby suppressing the commutation failure of the hybrid commutation converter.

[0085] In other embodiments, step S3 can also set other preset rules to obtain a forced shutdown signal according to actual needs, thereby suppressing commutation failure of the hybrid commutation converter.

[0086] S4. Control the hybrid commutator to perform commutation operation according to the forced shutdown signal.

[0087] It should be noted that step S4 first controls the hybrid commutation converter to perform commutation operation based on the forced shutdown signal obtained in step S3, which enables large-scale new energy to achieve three-phase fault ride-through on the AC side of the receiving end through the DC transmission system. At the same time, it adaptively adjusts the forced shutdown signal of the reverse resistance type RB-IGCT device in the hybrid commutation converter to achieve better commutation failure resistance.

[0088] This application provides a method for suppressing commutation failure control in a hybrid commutation converter, comprising: acquiring the fault mode of a large-scale new energy transmission system via DC transmission, as well as the valve trigger pulse signal, valve current, and trigger angle of the hybrid commutation converter; determining a commutation failure suppression control strategy for the hybrid commutation converter based on the fault mode; if the commutation failure suppression control strategy is a forced shutdown mode, determining a first forced shutdown signal based on the valve trigger pulse signal and valve current; determining a delay time based on the trigger angle; determining a second forced shutdown signal based on the delay time and the valve trigger pulse signal; determining a forced shutdown signal for the forced shutdown mode based on the first and second forced shutdown signals; and controlling the hybrid commutation converter to perform commutation operation based on the forced shutdown signal. This method for suppressing commutation failure in a hybrid commutator determines the delay time based on the trigger angle and obtains the forced turn-off signal when the commutation failure suppression control strategy is set to forced turn-off mode. This enables large-scale renewable energy transmission systems to achieve three-phase fault ride-through on the AC side of the receiving end. Simultaneously, it adaptively adjusts the forced turn-off signal of the reverse-resistance type RB-IGCT device in the hybrid commutator to achieve better commutation failure resistance and avoid the inability of the reverse-resistance type RB-IGCT device in the hybrid commutator to turn off, thus preventing commutation failure. This solves the technical problem of untimely turn-off leading to commutation failure in existing hybrid commutator methods for suppressing commutation failure in large-scale renewable energy transmission systems via DC.

[0089] Figure 6 This is a schematic diagram illustrating the framework for obtaining the delay time in the method for suppressing commutation failure control of a hybrid commutator as described in the embodiments of this application.

[0090] like Figure 4 The delay time for obtaining the second forced turn-off signal is shown. Currently, a fixed delay time t is used, typically 2ms considering the commutation period. However, under severe faults such as a three-phase AC side ground fault at the receiving end, the valve current of the hybrid commutation converter cannot drop to zero. Therefore, the existing forced turn-off signal of the hybrid commutation converter cannot control the turn-off of the reverse-resistance RB-IGCT device. If the time interval between the occurrence of the first forced turn-off signal on the AC side and the detection of the valve current change rate turning from negative to positive is too long, commutation failure may have already occurred by the time the first forced turn-off signal is issued. In this case, the valve-controlled second forced turn-off signal of the hybrid commutation converter's HCC becomes the last line of defense against commutation failure. Therefore, the method for suppressing commutation failure in this hybrid commutation converter can determine the delay time for obtaining the second forced turn-off signal based on the real-time output firing angle of the hybrid commutation converter, ensuring that the forced turn-off signal of the hybrid commutation converter can control the turn-off of the reverse-resistance RB-IGCT device.

[0091] like Figure 6 As shown, in one embodiment of this application, determining the delay time based on the trigger angle includes:

[0092] Obtain the preset trigger angle and preset commutation delay time of the hybrid commutation converter;

[0093] The commutation delay coefficient of the hybrid commutator is determined based on the preset trigger angle and the trigger angle.

[0094] The delay time of the hybrid commutation converter is calculated based on the commutation delay coefficient and the preset commutation delay time.

[0095] It should be noted that the trigger preset angle can be set to 180°, and the preset commutation delay time can be set to 10ms. In the process of obtaining the second forced turn-off signal, the commutation failure suppression control method of this hybrid commutator improves the fixed delay time to an adaptive delay time t, ensuring that the obtained forced turn-off signal can control the turn-off of the reverse-resistance RB-IGCT device, allowing large-scale new energy to achieve three-phase fault ride-through on the AC side of the receiving end via the DC transmission system. For example... Figure 6As shown, α is the firing angle of the hybrid commutator HCC using constant DC voltage control output. 180°-α = commutation angle overlap angle μ + turn-off angle γ. This physical quantity characterizes the commutation process of a single valve group. (180°-α) divided by 180° and multiplied by 10ms corresponding to the 180° angle (360° corresponds to 20ms in a 50Hz system, and 10ms is the time corresponding to 180°) gives the delay time corresponding to the commutation process of the hybrid commutator HCC.

[0096] In this embodiment, when a severe AC fault such as three-phase grounding occurs at the receiving end of a large-scale new energy DC transmission system, the firing angle α of the hybrid commutator HCC, controlled by a constant DC voltage, rapidly increases. This corresponds to a decrease in the output delay time t, meaning... Figure 4 The second forced shutdown signal, as shown in the solution, will be set to 1 more quickly, which means that the valve in the commutation process will be forced to shut down earlier, so as to achieve better commutation failure resistance of the hybrid commutation converter (HCC).

[0097] It should be noted that the commutation failure suppression control method of this hybrid commutator obtains an adaptive delay time through the firing angle α. Compared with the original fixed delay time t, in the case of a fault on the AC side of the receiving end, according to the change of the control electrical quantity, the HCC valve of the hybrid commutator issues a faster forced shutdown signal to shut down the reverse resistance type RB-IGCT device that is in the process of commutation.

[0098] In other embodiments, the trigger preset angle and preset commutation delay time can also be set according to the actual application scenario of the hybrid commutation converter.

[0099] In one embodiment of this application, determining the commutation failure suppression control strategy for the hybrid commutator based on the failure mode includes:

[0100] If the fault mode is a single-phase ground fault on the AC side of the receiving end of a large-scale new energy transmission system via DC, then the control strategy to suppress commutation failure is the commutation enhancement mode.

[0101] If the fault mode is a three-phase ground fault on the AC side of the receiving end of a large-scale new energy transmission system via DC, then the control strategy to suppress commutation failure is the forced shutdown mode.

[0102] It should be noted that the method for suppressing commutation failure in this hybrid commutator selects different commutation failure suppression control strategies according to different faults, ensuring that the hybrid commutator forces the shutdown of the reverse-resistance type RB-IGCT device in the commutation process earlier, so as to achieve better commutation failure resistance capability of the hybrid commutator HCC and avoid commutation failure of the hybrid commutator HCC.

[0103] Figure 7This is a schematic diagram of the commutation enhancement mode in the commutation failure suppression control method of the hybrid commutation converter described in the embodiments of this application.

[0104] like Figure 7 As shown, in one embodiment of this application, the method for suppressing commutation failure control of the hybrid commutation converter further includes: if the commutation failure suppression control strategy is a commutation enhancement mode, determining a commutation enhancement signal based on the valve trigger pulse signal and the valve current; and controlling the hybrid commutation converter to perform commutation operation based on the commutation enhancement signal.

[0105] It should be noted that in obtaining the commutation enhancement signal, the valve trigger pulse signal can first be NOT processed to obtain the first signal; then the valve current can be compared with the valve current threshold to obtain the second signal; finally, the commutation enhancement signal can be obtained by performing a logical AND process on the first and second signals. In this embodiment, if the valve current is less than the valve current threshold, the output second signal is 1; if the valve current is not less than the valve current threshold, the output second signal is 0. The valve current threshold can be selected as 0.

[0106] In this embodiment, the commutation enhancement mode can be understood as follows: Zero-crossing detection is performed on the valve current flowing through the hybrid commutation converter. When the current flowing through the reverse-resistance RB-IGCT device is less than 0, the zero-crossing current detection outputs a second signal of 1, indicating that the current flowing through the hybrid commutation converter has crossed zero. When a minor fault occurs on the receiving end AC side of a large-scale new energy transmission system, causing an AC voltage drop, the inverter turn-off angle γ decreases, becoming less than the minimum turn-off angle γmin. In this case, the valve current crosses zero, but the reverse recovery time is insufficient. After detecting the current crossing zero, the commutation enhancement mode outputs a commutation enhancement signal, causing the valve current on the reverse-resistance RB-IGCT device to directly shut down after crossing zero.

[0107] Figure 8 This is a schematic diagram showing the variation curves of the firing angle and delay time for a three-phase AC side fault under the commutation failure suppression control method of the hybrid commutator described in this application embodiment. Figure 9 This is a schematic diagram of the signal curves under the three-phase AC side fault forced shutdown mode of the hybrid commutator's commutation failure suppression control method described in the embodiments of this application. Figure 10 This is a schematic diagram of the valve current curve for a three-phase AC side fault under the commutation failure suppression control method of the hybrid commutation converter described in this application embodiment.

[0108] In the embodiments of this application, the method for suppressing commutation failure of the hybrid commutator is verified using a large-scale new energy DC transmission system topology as shown in Figure 2 as an example. A three-phase metallic ground fault is set on the AC side of the receiving end, and the fault ride-through process is as follows: Figure 8 , Figure 9, Figure 10 As shown.

[0109] It should be noted that, as Figure 8 As shown, during the 12.5s period when a three-phase ground fault occurs on the AC side of the receiving end, the hybrid commutator HCC uses constant DC voltage control to increase the output firing angle. Figure 6 The adaptive delay time of the forced turn-off signal shown is reduced so that the second forced turn-off signal is set to 1 earlier, which can turn off the reverse-resistance type RB-IGCT device in the HCC commutation of the hybrid commutator more quickly. According to Figure 9 After a 12.5s fault, the output forced shutdown signal can be dominated by the second forced shutdown signal within the first 5ms of the fault. At this time, the delay time for obtaining the second forced shutdown signal is extremely small, and forced shutdown occurs very quickly after the trigger pulse of the hybrid commutator HCC arrives. This prevents the hybrid commutator HCC from shutting down too slowly in the early stages of the fault, thus better mitigating commutation failure. According to... Figure 10 The proposed method for suppressing commutation failure in hybrid commutator converters, with its improved forced shutdown valve control, achieves better AC three-phase fault ride-through compared to the original fixed delay t (t is set to 2ms). No commutation failure occurred in the HCC of the hybrid commutator converter, whereas the original valve-controlled fault ride-through method resulted in commutation failure in the HCC. Furthermore, the maximum valve current during the fault period is significantly reduced compared to the original control method, verifying the feasibility of this method.

[0110] Example 2:

[0111] Figure 11 This is a schematic diagram of the frame of the commutation failure suppression control device for the hybrid commutator described in the embodiments of this application.

[0112] like Figure 11 As shown, this application embodiment provides a commutation failure suppression control device for a hybrid commutation converter, which is applied to a large-scale new energy DC transmission system. The commutation failure suppression control device includes: a data acquisition module 100, a control strategy determination module 200, a signal determination module 300, and an execution module 400.

[0113] The data acquisition module 100 is used to acquire the fault modes of the large-scale new energy DC transmission system, as well as the valve trigger pulse signal, valve current and trigger angle of the hybrid commutation converter;

[0114] The control strategy determination module 200 is used to determine the control strategy for suppressing commutation failure of the hybrid commutation converter based on the fault mode.

[0115] The signal determination module 300 is used to determine a first forced shutdown signal based on the valve trigger pulse signal and valve current according to the forced shutdown mode of the commutation failure suppression control strategy; determine a delay time based on the trigger angle; determine a second forced shutdown signal based on the delay time and the valve trigger pulse signal; and determine the forced shutdown signal of the forced shutdown mode based on the first forced shutdown signal and the second forced shutdown signal.

[0116] The execution module 400 is used to control the hybrid commutator to perform commutation operation according to the forced shutdown signal.

[0117] It should be noted that the content of each module in the device of Embodiment 2 corresponds to the content of each step in the method of Embodiment 1. Therefore, the content of each module of the hybrid commutation converter suppression control device will not be repeated in this embodiment. When the commutation failure suppression control device of the hybrid commutation converter determines that the commutation failure suppression control strategy is in forced shutdown mode through the data acquisition module, control strategy determination module, signal determination module, and execution module, it determines the delay time based on the trigger angle and obtains the forced shutdown signal based on the delay time. This enables large-scale new energy to achieve three-phase fault ride-through on the AC side of the receiving end via the DC transmission system. Simultaneously, it adaptively adjusts the forced shutdown signal of the reverse-resistance RB-IGCT device in the hybrid commutation converter to achieve better commutation failure resistance and prevent the reverse-resistance RB-IGCT device in the hybrid commutation converter from failing to turn off, thus avoiding commutation failure.

[0118] In this embodiment, the signal determination module 300 includes a delay submodule, which is used to obtain the trigger preset angle and preset commutation delay time of the hybrid commutation converter; determine the commutation delay coefficient of the hybrid commutation converter according to the trigger preset angle and the trigger angle; and calculate the delay time of the hybrid commutation converter according to the commutation delay coefficient and the preset commutation delay time.

[0119] In this embodiment of the application, the signal determination module 300 further includes a signal determination submodule; the signal determination submodule is used to perform logical NOT processing on the valve trigger pulse signal to obtain a processed signal; and to perform delay processing on the processed signal according to the delay time to obtain a second forced shutdown signal.

[0120] In this embodiment of the application, the control strategy determination module 200 is further configured to, if the fault mode is a single-phase ground fault on the AC side of the receiving end of the large-scale new energy transmission system via DC transmission, then the commutation failure suppression control strategy is a commutation enhancement mode; or if the fault mode is a three-phase ground fault on the AC side of the receiving end of the large-scale new energy transmission system via DC transmission, then the commutation failure suppression control strategy is a forced shutdown mode.

[0121] Example 3:

[0122] Figure 12This is a schematic diagram of the terminal device described in an embodiment of this application.

[0123] like Figure 12 As shown, this application provides a terminal device, including a processor and a memory;

[0124] Memory is used to store program code and transfer the program code to the processor;

[0125] The processor is used to execute the above-mentioned method for suppressing commutation failure control of the hybrid commutator according to the instructions in the program code.

[0126] It should be noted that the processor is used to execute the steps in the above-described embodiment of a method for suppressing commutation failure control in a hybrid commutated converter according to instructions in the program code. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the above-described system / device embodiments.

[0127] For example, a computer program can be divided into one or more modules / units, one or more of which are stored in memory and executed by a processor to complete this application. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in a terminal device.

[0128] Terminal devices can be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. Terminal devices may include, but are not limited to, processors and memory. Those skilled in the art will understand that this does not constitute a limitation on the terminal device, which may include more or fewer components than illustrated, or combinations of certain components, or different components. For example, a terminal device may also include input / output devices, network access devices, buses, etc.

[0129] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0130] Memory can be an internal storage unit of a terminal device, such as a hard drive or RAM. Memory can also be an external storage device, such as a plug-in hard drive, SmartMedia Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, memory can include both internal and external storage units. Memory is used to store computer programs and other programs and data required by the terminal device. Memory can also be used to temporarily store data that has been output or will be output.

[0131] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0132] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0133] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0134] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0135] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0136] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for suppressing commutation failure control in a hybrid commutator, applied to a large-scale new energy transmission system via DC, characterized in that, The method for suppressing commutation failure control includes the following steps: The fault modes of the large-scale new energy DC transmission system are obtained, as well as the valve trigger pulse signal, valve current and trigger angle of the hybrid commutation converter; Based on the aforementioned failure modes, a commutation failure suppression control strategy for the hybrid commutation converter is determined. If the commutation failure suppression control strategy is a forced shutdown mode, a first forced shutdown signal is determined based on the valve trigger pulse signal and the valve current; a delay time is determined based on the trigger angle; a second forced shutdown signal is determined based on the delay time and the valve trigger pulse signal; and a forced shutdown signal for the forced shutdown mode is determined based on the first forced shutdown signal and the second forced shutdown signal. The hybrid commutator is controlled to perform commutation operation according to the forced shutdown signal.

2. The method for suppressing commutation failure control in a hybrid commutator according to claim 1, characterized in that, Determining the delay time based on the trigger angle includes: Obtain the preset trigger angle and preset commutation delay time of the hybrid commutator; The commutation delay coefficient of the hybrid commutator is determined based on the preset trigger angle and the trigger angle. The delay time of the hybrid commutation converter is calculated based on the commutation delay coefficient and the preset commutation delay time.

3. The method for suppressing commutation failure control in a hybrid commutator according to claim 1, characterized in that, The second forced shutdown signal is determined based on the delay time and the valve trigger pulse signal, including: The valve trigger pulse signal is subjected to logical NOT processing to obtain a processed signal; The processing signal is delayed according to the delay time to obtain a second forced shutdown signal.

4. The method for suppressing commutation failure control of a hybrid commutator according to any one of claims 1-3, characterized in that, Based on the aforementioned failure modes, the control strategy for suppressing commutation failure in the hybrid commutator includes: If the fault mode is a single-phase grounding fault on the AC side of the receiving end of the large-scale new energy transmission system via DC, then the commutation failure suppression control strategy is the commutation enhancement mode. If the fault mode is a three-phase grounding fault on the receiving end AC side of the large-scale new energy transmission system via DC, then the commutation failure suppression control strategy is a forced shutdown mode.

5. The method for suppressing commutation failure control of a hybrid commutator according to any one of claims 1-3, characterized in that, Also includes: If the commutation failure suppression control strategy is a commutation enhancement mode, the commutation enhancement signal is determined based on the valve trigger pulse signal and the valve current; The hybrid commutation converter is controlled to perform commutation operation according to the commutation enhancement signal.

6. A commutation failure suppression control device for a hybrid commutator, applied to a large-scale new energy DC transmission system, characterized in that, The commutation failure suppression control device includes: a data acquisition module, a control strategy determination module, a signal determination module, and an execution module; The data acquisition module is used to acquire the fault mode of the large-scale new energy DC transmission system, as well as the valve trigger pulse signal, valve current and trigger angle of the hybrid commutation converter; The control strategy determination module is used to determine the commutation failure suppression control strategy of the hybrid commutation converter according to the fault mode. The signal determination module is used to determine a first forced shutdown signal based on the valve trigger pulse signal and the valve current, according to the forced shutdown mode of the commutation failure suppression control strategy; determine a delay time based on the trigger angle; determine a second forced shutdown signal based on the delay time and the valve trigger pulse signal; and determine the forced shutdown signal of the forced shutdown mode based on the first forced shutdown signal and the second forced shutdown signal. The execution module is used to control the hybrid commutator to perform commutation operation according to the forced shutdown signal.

7. The commutation failure suppression control device for a hybrid commutator according to claim 6, characterized in that, The signal determination module includes a delay submodule, which is used to obtain the trigger preset angle and preset commutation delay time of the hybrid commutation converter; determine the commutation delay coefficient of the hybrid commutation converter according to the trigger preset angle and the trigger angle; and calculate the delay time of the hybrid commutation converter according to the commutation delay coefficient and the preset commutation delay time.

8. The commutation failure suppression control device for a hybrid commutator according to claim 7, characterized in that, The signal determination module further includes a signal determination submodule; the signal determination submodule is used to perform logical NOT processing on the valve trigger pulse signal to obtain a processed signal; and to perform delay processing on the processed signal according to the delay time to obtain a second forced shutdown signal.

9. The commutation failure suppression control device for a hybrid commutator according to claim 6, characterized in that, The control strategy determination module is further configured to, if the fault mode is a single-phase ground fault on the AC side of the receiving end of the large-scale new energy transmission system via DC, then the commutation failure suppression control strategy is a commutation enhancement mode; or if the fault mode is a three-phase ground fault on the AC side of the receiving end of the large-scale new energy transmission system via DC, then the commutation failure suppression control strategy is a forced shutdown mode.

10. A terminal device, characterized in that, Including the processor and memory; The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the method for suppressing commutation failure control of a hybrid commutator as described in any one of claims 1-5, according to instructions in the program code.

Images