A control method and device for suppressing commutation failure of a commutation valve based on fully controlled devices

Abstract

The present application relates to a control method, device and equipment for suppressing commutation failure of a commutation valve based on fully controlled devices. In this control method for suppressing commutation failure of a commutation valve based on fully controlled devices, each thyristor of the bridge arm of a conventional DC commutation valve is replaced with a fully controlled device, and the turn-off signal output is determined according to the parameters of the fully controlled device. Only when the fully controlled device is in a turn-offable state and receives a forced turn-off signal or a periodic turn-off signal, the corresponding fully controlled device is controlled to turn off after a turn-off delay time, that is, the bridge arm of the converter is blocked, and the current of the commutation valve is forced to commutate, realizing forced commutation of the commutation valve on the inverter side. By using this control method for suppressing commutation failure of a commutation valve based on fully controlled devices, commutation failure faults can be eliminated, and the safety and stability of a conventional DC power transmission system can be effectively improved; it solves the technical problem that the commutation failure phenomenon exists in the commutation valve control strategy of the existing conventional DC power transmission system, which is not conducive to the stable operation of the conventional DC power transmission system.

Description

Technical Field

[0001] The present application relates to the technical field of high-voltage direct current transmission, and in particular to a control method, device and equipment for suppressing commutation failure of a converter valve based on a fully controlled device. Background Art

[0002] High-voltage direct current transmission technology is a power transmission technology used for long-distance power transmission. It has developed rapidly in recent years, and the transmission capacity, voltage level, and transmission distance have been continuously improved. High-voltage direct current transmission technology includes conventional direct current transmission technology and flexible direct current transmission technology. Among them, conventional direct current based on line commutated converter based HVDC (LCC-HVDC) technology has a high stock ratio in high-voltage direct current transmission due to its large transmission capacity, long transmission distance, mature technology, and strong economy.

[0003] Commutation failure is an inherent problem of conventional DC transmission systems. Since conventional DC converter valves mainly use thyristors, which cannot actively shut down the current, the current between the bridge arms cannot automatically complete the phase change when a fault occurs on the AC side or the valve side, resulting in a commutation failure. Continuous commutation failures may cause voltage and current fluctuations on the DC side of the converter valve, thereby affecting power transmission and the stability of the frequency of the conventional DC transmission system, seriously endangering the long-term safe and stable operation of the conventional DC transmission system. Summary of the invention

[0004] The embodiments of the present application provide a control method, device and equipment for suppressing commutation failure of converter valves based on fully controlled devices, which is used to solve the technical problem that commutation failure exists in the control strategy of converter valves in existing conventional DC transmission systems, which is not conducive to the stable operation of conventional DC transmission systems.

[0005] In order to achieve the above objectives, the embodiments of the present application provide the following technical solutions:

[0006] On the one hand, a control method for suppressing commutation failure of a converter valve based on a fully controlled device is provided, comprising the following steps:

[0007] The topology structure, shutdown delay time and control signal of the inverter-side converter valve in the conventional direct current transmission system are obtained, and each thyristor of the topology structure is replaced with a fully controlled device;

[0008] Controlling the operation of all the fully-controlled devices in the converter valve according to the control signal, and acquiring the AC voltage of the converter valve and the conduction angle, device current, commutation margin and conduction period of each of the fully-controlled devices;

[0009] Process according to the conduction angle, the control signal, and the conduction period using the periodic signal processing rule to obtain a periodic turn-off signal corresponding to the fully controlled device; process according to the device current and the AC voltage using the misjudgment rule to obtain a forced turn-off signal corresponding to the fully controlled device.

[0010] Determine the switching state of the fully controlled device according to the device current and the control signal. When the switching state is the turn-off state and the periodic turn-off signal or the forced turn-off signal is received, control the corresponding fully controlled device to turn off after a delay of the turn-off delay time, so that the inverter-side commutation valve is forced to commutate.

[0011] Preferably, processing according to the conduction angle, the control signal, and the conduction period using the periodic signal processing rule to obtain a periodic turn-off signal corresponding to the fully controlled device includes:

[0012] Perform a NOT operation on the control signal to obtain a trigger signal.

[0013] Calculate according to the conduction period and the conduction angle to obtain a periodic delay length.

[0014] Calculate according to the periodic delay length and the commutation margin to obtain a preset delay length.

[0015] After delaying the trigger signal by the preset delay length, output a periodic turn-off signal.

[0016] Preferably, processing according to the device current and the AC voltage using the misjudgment rule to obtain a forced turn-off signal corresponding to the fully controlled device includes:

[0017] Process the device current using a differentiator to obtain a current change rate; compare the current change rate with the data in the change rate fault interval to obtain a change rate judgment result.

[0018] Compare the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively to obtain a comparison result.

[0019] If the comparison result is a non-misjudgment signal and the change rate judgment result is that the current change rate is within the data range of the change rate fault interval, then obtain a forced turn-off signal corresponding to the fully controlled device.

[0020] Preferably, comparing the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively to obtain a comparison result includes:

[0021] If the device current is less than the current preset value or the AC voltage is higher than the voltage preset value, then the output comparison result is a misjudgment signal.

[0022] If the device current is not less than the preset current value or the AC voltage is lower than the preset voltage value, the output comparison result is a no misjudgment signal;

[0023] Wherein, the AC voltage is composed of the single-phase voltages on the AC side of the three-phase converter valves. The content of the output comparison result being a misjudgment signal includes: the AC voltage and each single-phase voltage on the AC side of the converter valves are all higher than the preset voltage value.

[0024] Preferably, determining the switching state of the fully controlled device corresponding to the device current and the control signal includes:

[0025] If the control signal is a turn-on signal, perform a negation process on the turn-on signal to obtain the non-turn-on state corresponding to the fully controlled device;

[0026] If the state of the fully controlled device is the non-turn-on state and its device current is less than the maximum turn-off current corresponding to the fully controlled device, the switching state of the fully controlled device is the turn-off state.

[0027] On the other hand, a control device for suppressing commutation failure of a converter valve based on a fully controlled device is provided, including a data acquisition module, an operation and parameter acquisition module, a signal output module, and a commutation control module;

[0028] The data acquisition module is configured to acquire the topological structure, turn-off delay time, and control signal of the inverter-side converter valve in a conventional HVDC transmission system, and replace each thyristor of the topological structure with a fully controlled device;

[0029] The operation and parameter acquisition module is configured to control the operation of all the fully controlled devices in the converter valve according to the control signal, and acquire the AC voltage of the converter valve, as well as the conduction angle, device current, commutation margin, and conduction period of each fully controlled device;

[0030] The signal output module is configured to perform processing according to the conduction angle, the control signal, and the conduction period by using a periodic signal processing rule to obtain a periodic turn-off signal corresponding to the fully controlled device; perform processing according to the device current and the AC voltage by using a misjudgment rule to obtain a forced turn-off signal corresponding to the fully controlled device;

[0031] The commutation control module is configured to determine the switching state of the fully controlled device corresponding to the device current and the control signal, and control the corresponding fully controlled device to turn off after a delay of the turn-off delay time according to the switching state being the turn-off state and receiving the periodic turn-off signal or the forced turn-off signal, so as to force commutation of the inverter-side converter valve.

[0032] Preferably, the signal output module is further configured to invert the control signal to obtain a trigger signal, calculate a period delay length according to the conduction period and the conduction angle, calculate a preset delay length according to the period delay length and the commutation margin, and after delaying the trigger signal by the preset delay length, output a period turn-off signal.

[0033] Preferably, the signal output module includes a judgment sub-module, a comparison sub-module, and a signal output sub-module;

[0034] The judgment sub-module is configured to process the device current with a differentiator to obtain a current change rate; compare the current change rate with the change rate fault interval data to obtain a change rate judgment result;

[0035] The comparison sub-module is configured to compare the device current and the AC voltage with corresponding current preset values and voltage preset values respectively to obtain a comparison result;

[0036] The signal output sub-module is configured to obtain a forced turn-off signal corresponding to the fully-controlled device if the comparison result is a non-misjudgment signal and the change rate judgment result is that the current change rate is within the change rate fault interval data range;

[0037] Wherein, the comparison sub-module is further configured to output a misjudgment signal as the comparison result if the device current is less than the current preset value or the AC voltage is higher than the voltage preset value; output a non-misjudgment signal as the comparison result if the device current is not less than the current preset value or the AC voltage is lower than the voltage preset value;

[0038] The AC voltage is composed of the single-phase voltages on the AC side of the three-phase commutation valve. The content of the misjudgment signal output as the comparison result includes: the AC voltage and each single-phase voltage on the AC side of the commutation valve are higher than the voltage preset value.

[0039] Preferably, the control commutation module is further configured to invert the turn-on signal according to the control signal to obtain a non-turn-on state corresponding to the fully-controlled device; if the state of the fully-controlled device is the non-turn-on state and its device current is less than the maximum turn-off current corresponding to the fully-controlled device, the switch state of the fully-controlled device is a turn-off state.

[0040] On the other hand, a terminal device is provided, including a processor and a memory;

[0041] The memory is configured to store program code and transmit the program code to the processor;

[0042] The processor is configured to execute the above-mentioned method for suppressing commutation failure of a commutation valve based on fully-controlled devices according to the instructions in the program code.

[0043] The method, device, and equipment for suppressing commutation failure of a commutation valve based on fully-controlled devices. The method includes obtaining the topological structure, turn-off delay time, and control signal of the commutation valve on the inverter side in a conventional HVDC transmission system, and replacing each thyristor in the topological structure with a fully-controlled device; controlling all fully-controlled devices in the commutation valve to operate according to the control signal, and obtaining the AC voltage of the commutation valve, as well as the conduction angle, device current, commutation margin, and conduction period of each fully-controlled device; processing according to the conduction angle, control signal, and conduction period using the periodic signal processing rule to obtain the periodic turn-off signal corresponding to the fully-controlled device; processing according to the device current and AC voltage using the misjudgment rule to obtain the forced turn-off signal corresponding to the fully-controlled device; determining the switching state of the corresponding fully-controlled device according to the device current and control signal, and controlling the corresponding fully-controlled device to turn off after a delay of the turn-off delay time according to the switching state being a turn-off state and receiving the periodic turn-off signal or the forced turn-off signal, so as to force commutation of the commutation valve on the inverter side. From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages: The method for suppressing commutation failure of a commutation valve based on fully-controlled devices controls the corresponding fully-controlled device to turn off after a delay of the turn-off delay time by the fully-controlled device being in a turn-off state and receiving the forced turn-off signal or the periodic turn-off signal, that is, the bridge arm of the converter is blocked, and the current of the commutation valve is forced to commutate, realizing forced commutation of the commutation valve on the inverter side. By this method for suppressing commutation failure of a commutation valve based on fully-controlled devices, commutation failure faults can be eliminated, and the safety and stability of the conventional HVDC transmission system can be effectively improved; it solves the technical problem that the commutation failure phenomenon exists in the commutation valve control strategy in the existing conventional HVDC transmission system, which is not conducive to the stable operation of the conventional HVDC transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for describing the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a flowchart of the steps of the method for suppressing commutation failure of a commutation valve based on fully-controlled devices according to the embodiments of the present application;

[0046] Figure 2 It is a schematic diagram of the topological structure of the commutation valve on the inverter side in the method for suppressing commutation failure of a commutation valve based on fully-controlled devices according to the embodiments of the present application;

[0047] Figure 3 Schematic diagram of the framework of the commutation failure control method for suppressing a commutation valve based on fully controlled devices according to an embodiment of the present application;

[0048] Figure 4 Schematic diagram of the framework of the periodic signal processing rule in the commutation failure control method for suppressing a commutation valve based on fully controlled devices according to an embodiment of the present application;

[0049] Figure 5 Schematic diagram of the framework of the misjudgment rule in the commutation failure control method for suppressing a commutation valve based on fully controlled devices according to an embodiment of the present application;

[0050] Figure 6 Schematic diagram of the signals of the commutation of the middle arm of the commutation valve in the commutation failure control method for suppressing a commutation valve based on fully controlled devices according to an embodiment of the present application;

[0051] Figure 7 Schematic diagram of the simulation of a single-phase metal grounding fault occurring in a conventional HVDC transmission system in the commutation failure control method for suppressing a commutation valve based on fully controlled devices according to an embodiment of the present application;

[0052] Figure 8 Schematic diagram of the framework of the commutation failure control device for suppressing a commutation valve based on fully controlled devices according to an embodiment of the present application;

[0053] Figure 9 Schematic diagram of the terminal device according to an embodiment of the present application. Detailed implementation manners

[0054] To make the objectives, features, and advantages of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the embodiments described below are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0055] In the description of the embodiments of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0056] In the embodiments of the present application, unless otherwise clearly specified or limited, the terms "installation", "connection", "connection", "fixation", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0057] The embodiments of the present application provide a method, device, and equipment for suppressing commutation failure of a commutation valve based on fully controlled devices, which solve the technical problem that the commutation failure phenomenon exists in the commutation valve control strategy in the existing conventional DC transmission system, which is not conducive to the stable operation of the conventional DC transmission system.

[0058] Embodiment 1:

[0059] Figure 1 It is a flowchart of the steps of the method for suppressing commutation failure of a commutation valve based on fully controlled devices described in the embodiments of the present application. Figure 2 It is a schematic diagram of the topological structure of the commutation valve on the inverter side in the method for suppressing commutation failure of a commutation valve based on fully controlled devices described in the embodiments of the present application. Figure 3 It is a schematic diagram of the framework of the method for suppressing commutation failure of a commutation valve based on fully controlled devices described in the embodiments of the present application.

[0060] As Figures 1 to 3 shown, the embodiments of the present application provide a method for suppressing commutation failure of a commutation valve based on fully controlled devices, including the following steps:

[0061] S1. Obtain the topological structure, turn-off delay time, and control signal of the commutation valve on the inverter side in the conventional DC transmission system, and replace each thyristor of the topological structure with a fully controlled device.

[0062] It should be noted that in step S1, according to the topological structure of the commutation valve on the inverter side in the conventional DC transmission system as Figure 2 shown, all thyristors in the topological structure are replaced with fully controlled devices. The fully controlled device can be called a fully controlled power electronic device, and the fully controlled power electronic device can be a power electronic device with an active turn-off ability such as IGCT, GTO, IGBT, SCR, etc. In step S1, the turn-off delay time and control signal of the commutation valve on the inverter side in the conventional DC transmission system are also obtained to provide analysis data for the commutation of the subsequent commutation valve. In this embodiment, as Figure 3As shown in the figure, the control of a conventional HVDC transmission system includes an AC system, fully controlled devices and auxiliary branches, a DC line, a control unit, and a valve control unit. The control unit is used to output control signals. The AC system refers to the power consumption system. The valve control unit is used to control the operation of the fully controlled devices and auxiliary branches according to the control signals output by the control unit and the measurement data. The valve control unit can control the commutation of the converter valve by using the commutation failure control method based on fully controlled devices according to the control signals and measurement data. A conventional HVDC transmission system refers to a HVDC transmission system composed of a rectifier station, an inverter station, and a DC transmission line.

[0063] In the embodiment of the present application, the fully controlled power electronic device is equipped with a buffer absorption circuit and a voltage equalizing circuit, and lightning arresters are arranged at both ends of several series circuits.

[0064] S2. Control the operation of all fully controlled devices in the converter valve according to the control signal, and obtain the AC voltage of the converter valve, as well as the conduction angle, device current, commutation margin, and conduction period of each fully controlled device.

[0065] It should be noted that in step S2, the operation of the converter valve is controlled according to the control signal in step S1, and the conduction angles, device currents, commutation margins, and conduction periods of the converter and each fully controlled device are obtained. In this embodiment, the measurement data includes the turn-off delay time of the converter valve, the AC voltage, as well as the conduction angle, device current, commutation margin, and conduction period of the fully controlled device, etc. Among them, the device current can be obtained by collecting the current flowing through the fully controlled device through a current transformer or an ammeter. The AC voltage can be obtained by a voltage measuring device on the inverter side of the converter valve, and the voltage measuring device on the inverter side of the converter valve can be selected as a voltage transformer.

[0066] In the embodiment of the present application, during the process of controlling the operation of all fully controlled devices in the converter valve according to the control signal, the original conduction triggering logic of the thyristors in the converter valve is used to control the operation of all fully controlled devices in the converter valve.

[0067] S3. Process according to the conduction angle, control signal, and conduction period by using the periodic signal processing rule to obtain the periodic turn-off signal corresponding to the fully controlled device; process according to the device current and AC voltage by using the misjudgment rule to obtain the forced turn-off signal corresponding to the fully controlled device.

[0068] It should be noted that in step S3, the data obtained in step S1 and the data obtained in step S2 are processed by using the periodic signal processing rule and the misjudgment rule to obtain the corresponding periodic turn-off signal and forced turn-off signal, providing data for the forced commutation of the converter valve in the subsequent process.

[0069] S4. Determine the switching state of the corresponding fully-controlled device according to the device current and the control signal. When the switching state is the turn-off state and a periodic turn-off signal or a forced turn-off signal is received, control the corresponding fully-controlled device to turn off after a turn-off delay time, so as to force commutation of the inverter-side converter valve.

[0070] It should be noted that in step S4, first determine the switching state of the fully-controlled device according to the control signal in step S1 and the device current in step S2. Then, when the switching state of the fully-controlled device is the turn-off state and a periodic turn-off signal or a forced turn-off signal is received, control the corresponding fully-controlled device to turn off after a turn-off delay time, so as to force commutation of the inverter-side converter valve, which can prevent the problem of commutation failure at the receiving end of the conventional DC power transmission system, reduce the reactive power demand of the converter valve during the AC side fault, and improve the operation safety and stability of the conventional DC power transmission system. In this embodiment, the turn-off delay time of the fully-controlled device includes a turn-off determination window delay and a turn-off action delay. The turn-off determination window delay requires the fully-controlled device to continuously output a turn-off signal for a certain duration to prevent misoperation of the fully-controlled device caused by signal jitter. The typical value of the turn-off determination window delay is 70 μs. The turn-off action delay refers to the buffer time for the fully-controlled device to change from the on state to the off state. The typical value of the turn-off action delay is 400 μs. The turn-off delay time is related to engineering requirements and the characteristics of the fully-controlled device and is adjusted according to actual needs.

[0071] In the embodiment of the present application, the control method for suppressing commutation failure of the converter valve based on fully-controlled devices replaces the thyristors in the inverter-side converter topology of the conventional DC power transmission system with fully-controlled devices, and triggers the fully-controlled devices to conduct according to the fundamental frequency modulation signal of the control signal. The triggering logic is the same as the original thyristor triggering logic. The control method for suppressing commutation failure of the converter valve based on fully-controlled devices controls the fully-controlled devices to perform commutation of the converter valve and newly adds a forced turn-off control strategy. The forced turn-off control strategy includes a periodic turn-off logic and a current change rate interval turn-off logic. The periodic delay turn-off logic processes the conduction angle, the control signal, and the conduction period through the periodic signal processing rule to obtain a periodic turn-off signal. The current change rate interval turn-off logic processes the device current and the AC voltage through the misjudgment rule to obtain a forced turn-off signal. If the fully-controlled device meets the turn-off state and receives a forced turn-off signal or a periodic turn-off signal, control the corresponding fully-controlled device to turn off after a turn-off delay time, that is, the bridge arm of the converter is blocked, and the current of the converter valve is forced to commutate, realizing forced commutation of the inverter-side converter valve. Through the control method for suppressing commutation failure of the converter valve based on fully-controlled devices, commutation failure faults can be eliminated, and the safety and stability of the conventional DC power transmission system can be effectively improved.

[0072] A commutation failure control method for suppressing a commutation valve based on fully controlled devices provided by the present application. The method includes obtaining the topological structure, turn-off delay time, and control signal of the commutation valve on the inverter side in a conventional HVDC transmission system, and replacing each thyristor in the topological structure with a fully controlled device; controlling the operation of all fully controlled devices in the commutation valve according to the control signal, and obtaining the AC voltage of the commutation valve, as well as the conduction angle, device current, commutation margin, and conduction period of each fully controlled device; processing according to the conduction angle, control signal, and conduction period using the periodic signal processing rule to obtain the periodic turn-off signal of the corresponding fully controlled device; processing according to the device current and AC voltage using the misjudgment rule to obtain the forced turn-off signal of the corresponding fully controlled device; determining the switching state of the corresponding fully controlled device according to the device current and control signal, and controlling the corresponding fully controlled device to turn off after a delay of the turn-off delay time according to the switching state being the turn-off state and receiving the periodic turn-off signal or the forced turn-off signal, so as to force the commutation of the commutation valve on the inverter side. This commutation failure control method for suppressing a commutation valve based on fully controlled devices controls the corresponding fully controlled device to turn off after a delay of the turn-off delay time by the fully controlled device being in the turn-off state and receiving the forced turn-off signal or the periodic turn-off signal, that is, the bridge arm of the converter is blocked, and the current of the commutation valve is forced to commutate, realizing the forced commutation of the commutation valve on the inverter side. By this commutation failure control method for suppressing a commutation valve based on fully controlled devices, commutation failure faults can be eliminated, and the safety and stability of the conventional HVDC transmission system can be effectively improved; it solves the technical problem that the commutation failure phenomenon exists in the commutation valve control strategy in the existing conventional HVDC transmission system, which is not conducive to the stable operation of the conventional HVDC transmission system.

[0073] Figure 4 It is a frame schematic diagram of the periodic signal processing rule in the commutation failure control method for suppressing a commutation valve based on fully controlled devices described in the embodiment of the present application.

[0074] As Figure 4 shown, in an embodiment of the present application, processing according to the conduction angle, control signal, and conduction period using the periodic signal processing rule to obtain the periodic turn-off signal of the corresponding fully controlled device includes:

[0075] Performing a NOT operation on the control signal to obtain a trigger signal;

[0076] Calculating according to the conduction period and conduction angle to obtain a periodic delay length;

[0077] Calculating according to the periodic delay length and commutation margin to obtain a preset delay length;

[0078] After delaying the trigger signal by the preset delay length, outputting a periodic turn-off signal.

[0079] It should be noted that the cycle delay length of the fully controlled device is obtained by subtracting the conduction angle from the conduction cycle; the preset delay length is obtained by subtracting the commutation margin from the cycle delay length, and the preset delay length and the trigger signal are input into the fully controlled device to control the operation of the fully controlled device. After a delay of the preset delay length, the fully controlled device outputs the preset delay length according to the trigger signal. In this embodiment, the cycle delay length can also be the maximum remaining conduction time of the fully controlled device in the bridge arm, and the conduction cycle can be selected as π. A part of the time in the cycle delay length is intercepted as the commutation margin, and the other remaining time length is used as the preset delay length.

[0080] Figure 5 It is a schematic diagram of the framework of the misjudgment rule in the commutation failure control method of the thyristor valve based on the fully controlled device described in the embodiment of the present application.

[0081] As Figure 5 shown, in an embodiment of the present application, according to the device current and the AC voltage, the misjudgment rule is used for processing, and the forced turn-off signal corresponding to the fully controlled device is obtained, including:

[0082] The device current is processed by a differentiator to obtain the current change rate; according to the comparison between the current change rate and the data in the change rate fault interval, the change rate judgment result is obtained;

[0083] According to the comparison between the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively, the comparison result is obtained;

[0084] If the comparison result is a non-misjudgment signal and the change rate judgment result is that the current change rate is within the data range of the change rate fault interval, the forced turn-off signal corresponding to the fully controlled device is obtained;

[0085] Among them, according to the comparison between the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively, the comparison result includes: if the device current is less than the current preset value or the AC voltage is higher than the voltage preset value, the output comparison result is a misjudgment signal; if the device current is not less than the current preset value or the AC voltage is lower than the voltage preset value, the output comparison result is a non-misjudgment signal; the AC voltage is composed of the single-phase voltage on the AC side of the thyristor valve of three phases, and the content of the output comparison result being a misjudgment signal includes: the AC voltage and the single-phase voltage on the AC side of each thyristor valve are both higher than the voltage preset value.

[0086] It should be noted that the data of the rate-of-change fault interval includes. For fully controlled devices, the rate-of-change fault interval of the current encompasses both the current rising and falling processes, and the data of the rate-of-change fault interval of the current is determined by the topological parameters of the converter valve and the AC system side. For example: Taking the positive maximum value of the rate of change of the current of the fully controlled device in the arm during the natural commutation process under full power operation as the reference value. The upper bound value of the fault rate of change should not exceed 0.3 pu of the reference value, where this pu is the per-unit value of the reference value, and the lower bound value of the fault rate of change should not be less than -0.8 pu of the reference. Specifically, the upper bound value of the fault rate of change and the lower bound value of the fault rate of change of the rate-of-change fault interval data should be adjusted according to the actual engineering requirements. In this embodiment, if the rate of change of the current is between the lower bound value of the fault rate of change and the upper bound value of the fault rate of change, then the rate of change of the current is within the range of the rate-of-change fault interval data; if the rate of change of the current is less than the lower bound value of the fault rate of change or the rate of change of the current is greater than the upper bound value of the fault rate of change, then the rate of change of the current is not within the range of the rate-of-change fault interval data. The voltage preset value can be selected as 0.95 times the rated voltage of the AC side of the converter valve.

[0087] In the embodiment of the present application, according to the device current being less than the current preset value, a misjudgment signal is output, and the misjudgment signal can be used as a guiding parameter for correcting the control strategy of the converter valve, which can further prevent misoperation of the fully controlled device caused by a low rate of change of the current during low-power operation or at the end of the commutation process.

[0088] It should be noted that the current preset value should be less than 0.3 times the arm current of the converter valve under full power operation. The current preset value may also need to be adjusted according to the actual project.

[0089] In an embodiment of the present application, determining the switching state of the corresponding fully controlled device according to the device current and the control signal includes:

[0090] If the control signal is an on signal, the on signal is negated to obtain the non-on state of the corresponding fully controlled device;

[0091] If the state of the fully controlled device is the non-on state and its device current is less than the maximum turn-off current of the corresponding fully controlled device, then the switching state of the fully controlled device is the turn-off state.

[0092] Figure 6 This is a signal schematic diagram of the arm commutation of the converter valve in the control method for suppressing commutation failure of the converter valve based on fully controlled devices described in the embodiment of the present application. Figure 7 This is a simulation schematic diagram of a single-phase metal grounding fault occurring in a conventional HVDC transmission system in the control method for suppressing commutation failure of the converter valve based on fully controlled devices described in the embodiment of the present application.

[0093] In the embodiment of the present application, the commutation failure control method of the suppression commutation valve based on fully controlled devices is used to simulate the single-phase voltage drop fault on the inverter side of the conventional HVDC system, and the commutation process of the fault-phase bridge arm current and the action condition of the active turn-off signal are obtained as shown in Figure 6 The commutation failure control method of the suppression commutation valve based on fully controlled devices is used to simulate the single-phase metal grounding fault on the inverter side of the conventional HVDC system, and the simulation results are obtained as shown in Figure 7 The simulation results include AC current, commutation valve bridge arm current, active and reactive power, and DC voltage. When a fault occurs in the conventional HVDC system, the commutation failure control method of the suppression commutation valve based on fully controlled devices can effectively complete the commutation between bridge arms, resist the occurrence of commutation failure, and quickly restore the conventional HVDC system to a steady state after the fault.

[0094] Embodiment 2:

[0095] Figure 8 It is a frame schematic diagram of the commutation failure control device of the suppression commutation valve based on fully controlled devices described in the embodiment of the present application.

[0096] As shown in Figure 8 The embodiment of the present application provides a commutation failure control device of the suppression commutation valve based on fully controlled devices, including a data acquisition module 10, an operation and parameter acquisition module 20, a signal output module 30, and a commutation control module 40;

[0097] The data acquisition module 10 is configured to acquire the topological structure, turn-off delay time, and control signal of the commutation valve on the inverter side of the conventional HVDC system, and replace each thyristor of the topological structure with a fully controlled device;

[0098] The operation and parameter acquisition module 20 is configured to control the operation of all fully controlled devices in the commutation valve according to the control signal, and acquire the AC voltage of the commutation valve, as well as the conduction angle, device current, commutation margin, and conduction period of each fully controlled device;

[0099] The signal output module 30 is configured to process according to the conduction angle, control signal, and conduction period using the periodic signal processing rule to obtain the periodic turn-off signal of the corresponding fully controlled device; process according to the device current and AC voltage using the misjudgment rule to obtain the forced turn-off signal of the corresponding fully controlled device;

[0100] The commutation control module 40 is configured to determine the switch state of the corresponding fully controlled device according to the device current and control signal, and control the corresponding fully controlled device to turn off after a delay of the turn-off delay time according to the switch state being the turn-off state and receiving the periodic turn-off signal or the forced turn-off signal, so as to force the commutation of the commutation valve on the inverter side.

[0101] In the embodiment of the present application, the signal output module 30 is further configured to perform a NOT operation on the control signal to obtain a trigger signal, calculate a period delay length according to the conduction period and the conduction angle, calculate a preset delay length according to the period delay length and the commutation margin, and after delaying the trigger signal by the preset delay length, output a period turn-off signal.

[0102] In the embodiment of the present application, the signal output module 30 includes a judgment sub-module, a comparison sub-module, and a signal output sub-module;

[0103] The judgment sub-module is configured to process the device current using a differentiator to obtain a current change rate; compare the current change rate with the data of the change rate fault interval to obtain a change rate judgment result;

[0104] The comparison sub-module is configured to compare the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively to obtain a comparison result;

[0105] The signal output sub-module is configured to obtain a forced turn-off signal of the corresponding fully-controlled device according to the comparison result being a non-misjudgment signal and the change rate judgment result being that the current change rate is within the data range of the change rate fault interval;

[0106] Among them, the comparison sub-module is further configured to output a misjudgment signal as the comparison result according to the device current being less than the current preset value or the AC voltage being higher than the voltage preset value; output a non-misjudgment signal as the comparison result according to the device current being not less than the current preset value or the AC voltage being lower than the voltage preset value;

[0107] The AC voltage is composed of the single-phase voltage on the AC side of the three-phase commutation valve. The content of the misjudgment signal output as the comparison result includes: the AC voltage and the single-phase voltage on the AC side of each commutation valve are higher than the voltage preset value.

[0108] In the embodiment of the present application, the control commutation module 40 is further configured to perform a NOT operation on the turn-on signal according to the control signal being a turn-on signal to obtain a non-turn-on state of the corresponding fully-controlled device; according to the state of the fully-controlled device being a non-turn-on state and its device current being less than the maximum turn-off current of the corresponding fully-controlled device, the switching state of the fully-controlled device is a turn-off state.

[0109] It should be noted that the content of the modules in the device of Embodiment 2 corresponds to the step content of the method in Embodiment 1. The content of the method for suppressing commutation failure of the commutation valve based on fully-controlled devices has been described in Embodiment 1, and the step content of the method for suppressing commutation failure of the commutation valve based on fully-controlled devices will not be elaborated in detail in this embodiment.

[0110] Embodiment 3:

[0111] Figure 9 It is a schematic diagram of the terminal device described in the embodiment of the present application.

[0112] As Figure 9 shown, an embodiment of the present application provides a terminal device, including a processor and a memory;

[0113] The memory is used to store program code and transmit the program code to the processor;

[0114] The processor is configured to execute the above-mentioned commutation failure control method for suppressing a commutation valve based on fully controlled devices according to the instructions in the program code.

[0115] It should be noted that the processor is configured to execute the steps in the above-mentioned embodiment of a commutation failure control method for suppressing a commutation valve based on fully controlled devices according to the instructions in the program code. Alternatively, when the processor executes a computer program, it implements the functions of each module / unit in the above-mentioned system / device embodiments.

[0116] Exemplarily, the computer program may be divided into one or more modules / units. One or more modules / units are stored in the memory and executed by the processor to complete the present application. One or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in the terminal device.

[0117] The terminal device may be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor and a memory. Those skilled in the art can understand that it does not constitute a limitation on the terminal device, and it may include more or fewer components than shown in the figure, or combine some components, or different components. For example, the terminal device may further include an input / output device, a network access device, a bus, etc.

[0118] The so-called processor may be a central processing unit (CPU), or may also be 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. The general-purpose processor may be a microprocessor, or the processor may also be any conventional processor, etc.

[0119] The memory can be an internal storage unit of the terminal device, such as the hard disk or memory of the terminal device. The memory can also be an external storage device of the terminal device, such as a plug-in hard disk equipped on the terminal device, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory can also include both the internal storage unit of the terminal device and the external storage device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory can also be used to temporarily store the data that has been output or will be output.

[0120] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0121] In several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0122] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0123] In addition, each functional unit in various embodiments of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0124] When the integrated unit is implemented in the form of 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 this application, in essence, or the part that contributes to the prior art, or all or part of this 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 for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0125] As described above, the above 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 of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of various embodiments of this application.

Claims

1. A control method for suppressing commutation failure of a converter valve based on a fully controlled device, characterized in that: The following steps are involved: The topology structure, shutdown delay time and control signal of the inverter-side converter valve in the conventional direct current transmission system are obtained, and each thyristor of the topology structure is replaced with a fully controlled device; Controlling the operation of all the fully-controlled devices in the converter valve according to the control signal, and acquiring the AC voltage of the converter valve and the conduction angle, device current, commutation margin and conduction period of each of the fully-controlled devices; According to the conduction angle, the control signal and the conduction period, a periodic signal processing rule is used to process to obtain a periodic shutdown signal corresponding to the fully-controlled device; according to the device current and the AC voltage, a misjudgment rule is used to process to obtain a forced shutdown signal corresponding to the fully-controlled device; Determine the switch state of the corresponding fully-controlled device according to the device current and the control signal, and control the corresponding fully-controlled device to be turned off after the turn-off delay time is delayed according to the turn-off delay time, so as to force the inverter-side converter valve to commutate; According to the conduction angle, the control signal and the conduction period, a periodic signal processing rule is used to process and obtain a periodic shutdown signal corresponding to the fully controlled device, including: Performing negation processing on the control signal to obtain a trigger signal; Calculating according to the conduction period and the conduction angle to obtain a period delay length; Calculating according to the periodic delay length and the commutation margin to obtain a preset delay length; After delaying the trigger signal according to the preset delay length, outputting a periodic shut-off signal; The forced shutdown signal corresponding to the fully controlled device is obtained by processing the device current and the AC voltage using a misjudgment rule, including: The device current is processed by a differentiator to obtain a current change rate; and a change rate judgment result is obtained by comparing the current change rate with the change rate fault interval data; Obtaining a comparison result by comparing the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively; If the comparison result is a non-false judgment signal and the change rate judgment result is that the current change rate is within the change rate fault interval data range, a forced shutdown signal corresponding to the fully controlled device is obtained; The comparison results obtained by comparing the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively include: If the device current is less than the preset current value or the AC voltage is higher than the preset voltage value, the comparison result output is a false positive signal; If the device current is not less than the preset current value or the AC voltage is lower than the preset voltage value, the comparison result output is a no-misjudgment signal; Among them, the AC voltage is composed of the three-phase single-phase voltage on the AC side of the converter valve, and the output comparison result is a misjudgment signal including: the AC voltage and the single-phase voltage on the AC side of each converter valve are higher than the voltage preset value.

2. The control method for suppressing commutation failure of a converter valve based on a fully controlled device according to claim 1, characterized in that: Determining the switch state of the corresponding fully-controlled device according to the device current and the control signal includes: If the control signal is an on signal, negate the on signal to obtain a non-on state corresponding to the fully-controlled device; If the state of the fully-controlled device is a non-on state and the device current is less than the maximum off current corresponding to the fully-controlled device, the switch state of the fully-controlled device is a turnable state.

3. A control device for suppressing commutation failure of a converter valve based on a fully controlled device, characterized in that: It includes a data acquisition module, an operation and parameter acquisition module, a signal output module and a control commutation module; The data acquisition module is used to obtain the topological structure, shutdown delay time and control signal of the inverter-side converter valve in the conventional direct current transmission system, and replace each thyristor of the topological structure with a fully controlled device; The operation and parameter acquisition module is used to control the operation of all the fully-controlled devices in the converter valve according to the control signal, and obtain the AC voltage of the converter valve and the conduction angle, device current, commutation margin and conduction period of each of the fully-controlled devices; The signal output module is used to process the conduction angle, the control signal and the conduction period using a periodic signal processing rule to obtain a periodic shutdown signal corresponding to the fully-controlled device; and to process the device current and the AC voltage using a misjudgment rule to obtain a forced shutdown signal corresponding to the fully-controlled device; The control commutation module is used to determine the switch state of the corresponding fully-controlled device according to the device current and the control signal, and control the corresponding fully-controlled device to be turned off after the shutdown delay time is delayed according to the switch state being a turnable state and receiving the periodic shutdown signal or the forced shutdown signal, so as to force the inverter-side converter valve to commutate; The signal output module is further used to perform negation processing on the control signal to obtain a trigger signal, calculate a period delay length according to the conduction period and the conduction angle, calculate a preset delay length according to the period delay length and the commutation margin, and output a period shutdown signal after delaying the trigger signal according to the preset delay length; The signal output module includes a judgment submodule, a comparison submodule and a signal output submodule; The judgment submodule is used to process the device current using a differentiator to obtain a current change rate; Obtaining a change rate judgment result based on the comparison between the current change rate and the change rate fault interval data; The comparison submodule is used to compare the device current and the AC voltage with the corresponding current preset value and voltage preset value respectively to obtain a comparison result; The signal output submodule is used to obtain a forced shutdown signal corresponding to the fully controlled device according to the comparison result being a no-misjudgment signal and the change rate judgment result being that the current change rate is within the change rate fault interval data range; Wherein, the comparison submodule is further used for outputting the comparison result as a false positive signal according to the device current being less than the current preset value or the AC voltage being higher than the voltage preset value; and outputting the comparison result as a non-false positive signal according to the device current being not less than the current preset value or the AC voltage being lower than the voltage preset value; The AC voltage is composed of the three-phase single-phase voltage on the AC side of the converter valve, and the output comparison result is a misjudgment signal including: the AC voltage and each single-phase voltage on the AC side of the converter valve are higher than the preset voltage value.

4. The control device for suppressing commutation failure of converter valves based on a fully controlled device according to claim 3 is characterized in that: The control switching module is also used to perform negation processing on the opening signal according to the control signal being an opening signal, so as to obtain a non-opening state corresponding to the fully-controlled device; according to the state of the fully-controlled device being a non-opening state and the device current being less than the maximum shut-off current corresponding to the fully-controlled device, the switch state of the fully-controlled device is a shut-off state.

5. A terminal device, characterized in that: including a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the control method for suppressing commutation failure of a converter valve based on a fully controlled device as described in claim 1 or 2 according to the instructions in the program code.

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