Method and related equipment for suppressing commutation failure of high voltage direct current transmission under single-phase fault

Abstract

The present invention provides a method and related equipment for suppressing commutation failure of high-voltage direct current transmission under single-phase fault, which divides each commutation process within one cycle on the inverter side of the high-voltage direct current transmission system, and determines the commutation voltage corresponding to each commutation process; calculates the amplitude drop and phase shift of the commutation voltage corresponding to different fault degrees under the single-phase fault, and obtains amplitude drop data and phase shift data, which are used to analyze each commutation process, and determine the commutation process with high commutation failure risk and low commutation failure risk; analyzes the control method of the high-voltage direct current transmission system, and obtains the advance triggering amount; detects the commutation process of the target high-voltage direct current transmission system through the control system, obtains the detection result, and sends a corresponding control signal based on the detection result to suppress the commutation failure of the target high-voltage direct current transmission system; reduces the risk of commutation failure in the system, and ensures the safe and stable operation of the high-voltage direct current transmission system.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage direct current transmission, and in particular to a method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault and related equipment. Background Art

[0002] The HVDC transmission system has the advantages of large transmission capacity, long transmission distance, strong control performance and no need to consider synchronization issues. It is widely used in long-distance power transmission and regional large-scale power grid interconnection, becoming an important means of long-distance and large-capacity power transmission. The basic principle of HVDC transmission is that the rectifier at the sending end of HVDC transmission rectifies AC into DC, and transmits power to the receiving end inverter through the HVDC transmission line. The inverter then inverts DC into AC, and finally feeds it into the receiving end AC system.

[0003] With the completion of AC / DC hybrid power grids and the increase in the proportion of DC transmission capacity, the relative strength of the AC system at the receiving end has gradually decreased, and the "strong DC and weak AC" characteristics of large AC / DC hybrid power grids have gradually become prominent.

[0004] Since traditional high-voltage direct current transmission uses thyristors without self-shutoff capability as commutation elements, the inverter may fail to commutate after an AC fault occurs, resulting in a drop in DC voltage, DC current overcurrent, and AC voltage distortion. If there is no timely and appropriate control method, the DC system may experience multiple commutation failures, which will cause a large fluctuation in the transmission power and even lead to DC locking. The huge power impact will further lead to power oscillation, frequency fluctuation, and a large number of new energy disconnections in the AC system at the sending and receiving ends, which seriously threatens the safe and stable operation of the power grid.

[0005] In HVDC transmission systems, nearly 90% of commutation failures are caused by AC system faults on the inverter side, and most of the AC faults are single-phase faults. Therefore, it is of great significance to propose a method to improve the commutation failure resistance capability for the commutation failure problem of DC transmission systems under single-phase faults. Summary of the invention

[0006] The present invention provides a method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault and related equipment, the purpose of which is to reduce the risk of commutation failure in the system and ensure the safe and stable operation of the high-voltage direct current transmission system.

[0007] In order to achieve the above object, the present invention provides a method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault, which is applied to a high-voltage direct current transmission system, comprising:

[0008] Step 1, dividing each commutation process within one cycle of the inverter side in the high voltage direct current transmission system, and determining the commutation voltage corresponding to each commutation process;

[0009] Step 2, for the commutation voltage corresponding to each commutation process, calculate the amplitude drop and phase shift of the commutation voltage corresponding to different fault degrees under a single-phase fault, and obtain amplitude drop data and phase shift data;

[0010] Step 3: Analyze each commutation process according to the amplitude drop data and the phase shift data to determine the commutation process with a high risk of commutation failure and the commutation process with a low risk of commutation failure when a single-phase fault occurs;

[0011] Step 4, analyzing the control method of the high voltage direct current transmission system to obtain the advance triggering amount;

[0012] Step 5: Detecting the commutation process of the target high voltage direct current transmission system through the control system to obtain a detection result, and issuing a corresponding control signal based on the detection result to suppress commutation failure of the target high voltage direct current transmission system;

[0013] When the detection result is a commutation process with a high risk of commutation failure, the advance triggering amount is controlled by a control signal to suppress the commutation failure of the target HVDC transmission system;

[0014] When the detection result is a commutation process with a low risk of commutation failure, the control signal is used to stop or remove the advance trigger amount to suppress the commutation failure of the target high-voltage direct current transmission system.

[0015] Furthermore, the calculation expressions for the amplitude drop data and phase shift data are:

[0016]

[0017] in, Indicates the amplitude drop data, Indicates the commutation voltage amplitude during a fault. Indicates the rated amplitude of the commutation voltage, represents the phase offset data, represents the commutation process, , represents the initial phase of the commutation voltage at the time of fault, Indicates the initial phase of the commutation voltage under normal operating conditions.

[0018] More specifically, step 3 includes:

[0019] The turn-off angle of each commutation process is calculated based on the amplitude drop data and the phase shift data;

[0020] The commutation process with high commutation failure risk and the commutation process with low commutation failure risk are determined according to the turn-off angle when a single-phase fault occurs.

[0021] Furthermore, the calculation expression of the turn-off angle of each commutation process is:

[0022]

[0023] in, represents the cut-off angle, represents the equivalent commutation inductance, Indicates the DC current rating, Represents the firing angle in steady state.

[0024] To further explain, the calculation expression of the advance trigger amount is:

[0025]

[0026] in,

[0027]

[0028] In the formula, Indicates the advance trigger amount, represents the proportionality coefficient, represents the initial trigger angle, represents the trigger angle, represents the direct current, represents the amplitude of the commutation voltage, represents the reference turn-off angle, represents the phase advance angle, Indicates the commutation duration.

[0029] Furthermore, after step 5, the following steps are also included:

[0030] The commutation failure immunity factor is used to characterize the ability to suppress the commutation failure of the target HVDC transmission system. The calculation expression of the commutation failure immunity factor is:

[0031]

[0032] in, Indicates phase failure immune factor, represents the critical fault power, Indicates the DC rated power, Indicates the rated voltage of the AC bus. Indicates the critical impedance of commutation failure.

[0033] The present invention also provides a device for suppressing commutation failure of high-voltage direct current transmission under single-phase fault, which is applied to a high-voltage direct current transmission system, comprising:

[0034] A division module is used to divide each commutation process within one cycle of the inverter side in the high-voltage direct current transmission system and determine the commutation voltage corresponding to each commutation process;

[0035] A calculation module is used to calculate the amplitude drop and phase shift of the commutation voltage corresponding to each commutation process under a single-phase fault and corresponding to different fault degrees, and obtain amplitude drop data and phase shift data;

[0036] The first analysis module is used to analyze each commutation process according to the amplitude drop data and the phase offset data to determine the commutation process with a high risk of commutation failure and the commutation process with a low risk of commutation failure when a single-phase fault occurs;

[0037] The second analysis module is used to analyze the control method of the high voltage direct current transmission system to obtain the advance triggering amount;

[0038] A suppression module is used to detect the commutation process of the target high-voltage direct current transmission system through a control system, obtain a detection result, and issue a corresponding control signal based on the detection result to suppress the commutation failure of the target high-voltage direct current transmission system;

[0039] When the detection result is a commutation process with a high risk of commutation failure, the advance triggering amount is controlled by a control signal to suppress the commutation failure of the target HVDC transmission system;

[0040] When the detection result is a commutation process with a low risk of commutation failure, the control signal is used to stop or remove the advance trigger amount to suppress the commutation failure of the target high-voltage direct current transmission system.

[0041] The present invention also provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault is implemented.

[0042] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, a method for suppressing commutation failure of high-voltage direct current transmission under a single-phase fault is implemented.

[0043] The above scheme of the present invention has the following beneficial effects:

[0044] The present invention divides each commutation process within a cycle on the inverter side of a high-voltage direct current transmission system, and determines the commutation voltage corresponding to each commutation process; calculates the amplitude drop and phase shift of each commutation voltage corresponding to different fault degrees under a single-phase fault, and obtains amplitude drop data and phase shift data for analyzing each commutation process, and determines the commutation process with a high risk of commutation failure and the commutation process with a low risk of commutation failure when a single-phase fault occurs; analyzes the control method of the high-voltage direct current transmission system, and obtains the advance triggering amount; detects the commutation process of the target high-voltage direct current transmission system through the control system, and obtains the detection result, and when the detection result When the commutation process is high in risk of commutation failure, the advance triggering amount is controlled by a control signal to be put into operation; when the detection result is a commutation process with low risk of commutation failure, the advance triggering amount is stopped or removed by a control signal to suppress the commutation failure of the target high-voltage direct current transmission system; compared with the prior art, the present invention avoids the advance triggering in the low-risk commutation process under a single-phase fault, thereby preventing the commutation failure caused by reactive power fluctuation and voltage drop due to the advance triggering in the commutation process where no commutation failure would otherwise occur, while retaining the advance triggering for the high-risk commutation process, thereby reducing the risk of commutation failure in the system and ensuring the safe and stable operation of the high-voltage direct current transmission system.

[0045] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of a flow chart of an embodiment of the present invention;

[0047] Figure 2 A main circuit diagram of a high voltage direct current transmission system according to an embodiment of the present invention;

[0048] Figure 3 It is a curve diagram of amplitude variation in an embodiment of the present invention;

[0049] Figure 4 is a phase shift curve diagram in an embodiment of the present invention;

[0050] Figure 5 is a curve diagram showing the change of the turn-off angle with the degree of single-phase fault;

[0051] Figure 6 It is a simulation curve diagram of the phase switching failure immune factor in an embodiment of the present invention; Figure 6 (a) is a curve comparison diagram of the commutation failure immune factor under the control of the CIGRE model, the first control method, and the first control method using the control strategy proposed in the embodiment of the present invention; Figure 6(b) is a curve comparison diagram of the commutation failure immune factor under the control of the CIGRE model, the second control method, and the second control method using the control strategy proposed in the embodiment of the present invention;

[0052] Figure 7 This is a waveform diagram when the suppression method of the embodiment of the present invention is applied to the first control mode;

[0053] Figure 8 A waveform diagram when the suppression method of the embodiment of the present invention is applied to the second control mode;

[0054] Fig. 9 It is a structural block diagram of a device for suppressing commutation failure of high voltage direct current transmission under single-phase fault;

[0055] Fig.10 This is a structural block diagram of a terminal device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0060] In view of the existing problems, the present invention provides a method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault and related equipment.

[0061] like Figure 1 As shown, an embodiment of the present invention provides a method for suppressing commutation failure of high-voltage direct current transmission under a single-phase fault, which is applied to a high-voltage direct current transmission system, comprising:

[0062] Step 1, dividing each commutation process within one cycle of the inverter side in the high voltage direct current transmission system, and determining the commutation voltage corresponding to each commutation process;

[0063] Step 2, for the commutation voltage corresponding to each commutation process, calculate the amplitude drop and phase shift of the commutation voltage corresponding to different fault degrees under a single-phase fault, and obtain amplitude drop data and phase shift data;

[0064] Step 3: Analyze each commutation process according to the amplitude drop data and the phase shift data to determine the commutation process with a high risk of commutation failure and the commutation process with a low risk of commutation failure when a single-phase fault occurs;

[0065] Step 4, analyzing the control method of the high voltage direct current transmission system to obtain the advance triggering amount;

[0066] Step 5: Detecting the commutation process of the target high voltage direct current transmission system through the control system to obtain a detection result, and issuing a corresponding control signal based on the detection result to suppress commutation failure of the target high voltage direct current transmission system;

[0067] When the detection result is a commutation process with a high risk of commutation failure, the advance triggering amount is controlled by a control signal;

[0068] When the detection result is a commutation process with a low risk of commutation failure, the advance trigger amount is stopped or removed through a control signal.

[0069] The main circuit of the high voltage direct current transmission system in the embodiment of the present invention is as follows Figure 2 As shown, it specifically includes a sending-end power grid, a sending-end AC filter, a rectifier station, a DC line, an inverter station, a receiving-end power grid, and a receiving-end AC filter, wherein the output end of the sending-end power grid and the output end of the sending-end AC filter are connected to the input end of the rectifier station through a bus, the output end of the rectifier is connected to the input end of the DC line, the output end of the DC line is connected to the input end of the inverter station, and the output end of the inverter station is connected to the input end of the receiving-end power grid and the input end of the receiving-end AC filter through the bus.

[0070] Specifically, step 1 includes:

[0071] Assume that the commutation process at 1.500s of the CIGRE model in PSCAD / EMTDC during simulation is CP1, and the commutation process in the following cycle is divided into CP2 to CP12 in sequence, and the commutation voltage corresponding to each commutation process is determined as shown in Table 1 below:

[0072] Table 1 Reference table of commutation voltage corresponding to commutation process

[0073]

[0074] Among them, Y and D correspond to the DC side parameters of the YY transformer and the YD transformer respectively.

[0075] In the embodiment of the present invention, a phase A fault is taken as an example, and the three-phase voltage of the inverter-side grid in the high-voltage direct current transmission system is calculated by considering the fault location and the distortion of the non-fault phase under a single-phase fault. The calculation expression is:

[0076]

[0077] in, , , They represent the three-phase power supply voltage of the high-voltage direct current transmission system, Indicates the filter impedance on the inverter side busbar, , and are the line impedance and fault impedance on the left and right sides of the line fault point respectively, , , are the line currents on the secondary side of the YY transformer, , , are the line currents on the secondary side of the YD transformer, , are the transformation ratios of the YD transformer and the YY transformer respectively;

[0078] Calculate the three-phase voltage of the inverter side grid by considering the fault location and the distortion of the non-fault phase under single-phase fault , , Solve for the transformer secondary voltage:

[0079] For YY transformer:

[0080]

[0081] in, is the transformer leakage reactance, is the transformation ratio of the transformer;

[0082] For YD transformer:

[0083] ;

[0084] Based on the above formula, the amplitude drop data and phase shift data are calculated, and the calculation expression is:

[0085]

[0086] in, Indicates the amplitude drop data, Indicates the commutation voltage amplitude during a fault. Indicates the rated amplitude of the commutation voltage, represents the phase offset data, represents the commutation process, , represents the initial phase of the commutation voltage at the time of fault, Indicates the initial phase of the commutation voltage under normal operating conditions.

[0087] Specifically, step 3 includes:

[0088] The turn-off angle of each commutation process is calculated based on the amplitude drop data and the phase shift data;

[0089] The commutation process with high commutation failure risk and the commutation process with low commutation failure risk are determined according to the turn-off angle when a single-phase fault occurs.

[0090] Specifically, the calculation expression of the turn-off angle of each commutation process is:

[0091]

[0092] in, represents the cut-off angle, represents the equivalent commutation inductance, Indicates the DC current rating, Represents the firing angle in steady state.

[0093] The embodiment of the present invention is based on Figure 3 The amplitude change curves and Figure 4The analysis process of the phase shift curve for the amplitude drop data and phase shift data is as follows: it is known that the smaller the commutation voltage amplitude drop and the lagging phase shift, the more beneficial it is to commutation. Considering only the change in commutation voltage, it can be seen that the amplitude drop of CP1 / 7 is small, the phase lag is large, and the risk of commutation failure is low; the amplitude and phase of CP2 / 8 are almost unchanged, and the risk of commutation failure is low; the amplitude drop of CP3 / 9 is very small or even increases, but the phase advance is large, and the risk of commutation failure is medium; the amplitude drop of CP4 / 10 is small but the phase advance is large, and the risk of commutation failure is high; the amplitude drop of CP5 / 11 is large, the phase advance is large, and the risk of commutation failure is high; the amplitude drop of CP6 / 12 is high but the phase lag is extremely large, and the risk of commutation failure is low.

[0094] Then, combined with the change of commutation voltage fault, the curve of the turn-off angle of each commutation process changing with the degree of single-phase fault can be calculated from the above formula as follows: Figure 5 As shown, it can be seen that the turn-off angle of CP1 / 2 / 6 is always maintained at As shown above, the turn-off angle of CP3 quickly recovers to a positive value as the fault severity is alleviated. In contrast, the turn-off angle of CP4 / 5 is always at a positive value under more serious fault conditions. When the turn-off angle is lower than the critical value, commutation failure may occur. Judging from the change curve of the turn-off angle alone, the commutation failure risk of CP1 / 2 / 6 is extremely low, the risk of CP4 / 5 is high, and the risk of CP3 is at a medium level.

[0095] In the embodiment of the present invention, the commutation process CP1-CP12 is taken as an example, and it is determined through the shutdown angle that CP1 / 7, CP2 / 8, and CP6 / 12 are commutation processes with low commutation failure risks under phase A fault, and CP3 / 9, CP4 / 10, and CP5 / 11 are commutation processes with high commutation failure risks.

[0096] For a commutation process with a low risk of commutation failure, that is, a commutation process in which the corresponding commutation voltage deteriorates at a low level or is even conducive to commutation after a single-phase fault, the reactive power consumption and increased DC current caused by early triggering will increase the risk of commutation failure. If the early triggering amount is detected and controlled in a timely manner and stopped in the process with low commutation failure risk, the commutation failure resistance capability of the high-voltage direct current transmission system under a single-phase fault will be effectively improved. Therefore, the embodiment of the present invention needs to analyze the control method of the high-voltage direct current transmission system to obtain the early triggering amount.

[0097] Specifically, the calculation expression of the advance trigger amount is:

[0098]

[0099] In the formula, Indicates the advance trigger amount, represents the proportionality coefficient, represents the initial trigger angle, Indicates the trigger angle, proportional coefficient It can be obtained through a large number of simulation screening.

[0100] The embodiment of the present invention divides the existing control methods into:

[0101] Direct advance trigger type: after the fault is detected, the advance trigger amount is calculated and put into the trigger angle command;

[0102] Indirect advance trigger type: The advance trigger amount is indirectly added to the final trigger angle command, and the calculation accuracy is improved by considering the change of DC current during the commutation process, and the advance trigger amount is indirectly invested in the trigger angle command.

[0103] For direct advance trigger type, it is only necessary to detect and control the process of low commutation failure risk and stop the input advance trigger amount. For the indirect early trigger type, it may be necessary to analyze its mechanism, explore the source of its early trigger amount, and Extract it and first calculate the trigger angle. The formula is as follows:

[0104]

[0105] In the formula, represents the direct current, represents the amplitude of the commutation voltage, represents the reference turn-off angle, represents the phase advance angle, Indicates the commutation time. Under normal conditions, the inverter commutation angle ranges from about 20° to 30°, and the corresponding duration at power frequency is 1.11 to 1.67 ms. Considering that the commutation angle may increase during a fault, T can be conservatively taken as 2ms.

[0106] This method improves the calculation accuracy by considering the change of DC current during the commutation process, and indirectly puts the advance trigger amount into the trigger angle command. In order to obtain the extracted trigger amount, the trigger angle calculation command before considering the DC current change is set as the trigger angle before the advance trigger. , the calculation formula is as follows:

[0107] .

[0108] Specifically, the embodiment of the present invention detects the commutation process of the target high-voltage direct current transmission system through a control system to obtain a detection result; wherein, the control system adopts equal-interval trigger control, which sends an equal-interval trigger pulse signal sequence according to the trigger angle instruction and the AC voltage synchronization phase of the phase-locked loop to realize the trigger phase control of the converter. Under normal working conditions, one cycle of the converter is 0.02s. Under the condition of equal-interval triggering, 12 commutation processes can be evenly divided into 12 intervals of 1.67ms.

[0109] The overall control idea is: it can be divided into three situations: A, B, and C single-phase faults. The high / low commutation failure risk commutation process under B and C phase single-phase faults is 4 or 8 commutation processes pushed back from the situation under A phase fault. First, detect the previous trigger signal corresponding to the low-risk commutation process, and then detect the rising edge after delaying T1 through the integrator to send a judgment signal with a duration of about T2, that is, a state judgment signal is obtained from the moment before the low-risk process trigger signal starts to the moment before the next trigger signal starts. Finally, the corresponding state signal is output after judging the fault phase to control the advance trigger amount. Switching. T1 can be 1.5ms and T2 can be 1.67ms.

[0110] In order to eliminate the influence of short pulses in the trigger signal, the integrator is reset. The small pulse cannot make the integrator output large enough to trigger the comparator output rising edge, and the integrator will be reset in time after the trigger ends to reset the detection process. Since the trigger mode uses wide pulse triggering, in order to avoid the mutual influence of trigger signals with close time intervals, the detected trigger signal needs to be partitioned.

[0111] Specifically, after step 5, it also includes:

[0112] In order to reflect the failure suppression capability, the commutation failure immunity factor is used to characterize the ability to suppress the commutation failure of the target HVDC transmission system. The calculation expression of the commutation failure immunity factor is:

[0113]

[0114] in, Indicates the failure of phase change immune factor, represents the critical fault power, Indicates the DC rated power, Indicates the rated voltage of the AC bus. Indicates the critical impedance of commutation failure.

[0115] The embodiment of the present invention introduces the suppression method provided by the embodiment of the present invention into the high voltage DC commutation failure prevention method based on sine and cosine component detection, the predictive fixed arc extinction angle control and its improvement strategy for comparative analysis, as follows:

[0116] For the first control method, directly control the advance trigger amount Stop input during low risk commutation process.

[0117] For the second control method, take the DC current as the rated value and do not consider the change of the current and substitute it into its calculation module to obtain the value that does not include the advance trigger amount. The firing angle output , and the trigger angle of the control output Difference , in the low-risk commutation process, the controller's final firing angle command is compensated and added , normal operation during high-risk commutation process;

[0118] Taking the most common inductive ground short-circuit fault in actual engineering as an example, a ground fault is set at the AC busbar on the inverter side, and the electrical distance between the grounding point and the AC busbar is simulated by changing the inductance value; starting from 1.500s, the fault is set at a time interval of 0.001s, distributed to 1.511s, and the fault duration is 0.05s. The simulation results are as follows: Figure 6 The curve diagram of the phase switching failure immune factor is shown. Figure 7 The waveform diagram and Figure 8 The waveform diagram of the second control method shown is when the suppression method provided by the embodiment of the present invention is applied.

[0119] Figure 6 (a) is a curve comparison diagram of the commutation failure immune factor under the control of the CIGRE model, the first control method, and the first control method using the control strategy proposed in the embodiment of the present invention, Figure 6 (b) is a curve comparison diagram of the commutation failure immune factor under the control of the CIGRE model, the second control method, and the second control method using the control strategy proposed in the embodiment of the present invention; Figure 6 It can be seen that the commutation failure immunity factor after applying the inhibition method provided by the embodiment of the invention is higher under the two selected control strategies than the original strategy, that is, the commutation failure inhibition capability of the existing control strategy is enhanced.

[0120] Depend on Figure 7 It can be seen from the dotted box that after the advance trigger amount is stopped, that is, when the output trigger angle command is higher, the commutation failure that would occur in the original control at this time is successfully avoided.

[0121] Depend on Figure 8It can be seen from the dotted box that after the advance trigger amount is stopped, that is, when the output trigger angle command is higher, the commutation failure that would occur in the original control at this time is successfully avoided.

[0122] The embodiment of the present invention divides each commutation process within a cycle on the inverter side of a high-voltage direct current transmission system, and determines the commutation voltage corresponding to each commutation process; calculates the amplitude drop and phase shift of each commutation voltage corresponding to different fault degrees under a single-phase fault, and obtains amplitude drop data and phase shift data for analyzing each commutation process, and determines the commutation process with a high risk of commutation failure and the commutation process with a low risk of commutation failure when a single-phase fault occurs; analyzes the control method of the high-voltage direct current transmission system, and obtains the advance triggering amount; detects the commutation process of the target high-voltage direct current transmission system through the control system, and obtains the detection result, and when the detection result When the commutation process is high in risk of commutation failure, the advance triggering amount is controlled by a control signal to be put into operation; when the detection result is a commutation process with low risk of commutation failure, the advance triggering amount is stopped or removed by a control signal to suppress the commutation failure of the target high-voltage direct current transmission system; compared with the prior art, the embodiment of the present invention avoids the advance triggering in the low-risk commutation process under a single-phase fault, thereby preventing the commutation failure caused by reactive power fluctuation and voltage drop due to the advance triggering in the commutation process where the commutation failure would not occur, and at the same time retains the advance triggering of the high-risk commutation process, thereby reducing the risk of commutation failure in the system and ensuring the safe and stable operation of the high-voltage direct current transmission system.

[0123] like Fig. 9 As shown, the present invention also provides a high-voltage direct current transmission commutation failure suppression device 100 under a single-phase fault, which is applied to a high-voltage direct current transmission system. The high-voltage direct current transmission commutation failure suppression device 100 under a single-phase fault comprises:

[0124] The division module 101 is used to divide each commutation process within a cycle of the inverter side in the high voltage direct current transmission system, and determine the commutation voltage corresponding to each commutation process;

[0125] The calculation module 102 is used to calculate the amplitude drop and phase shift of the commutation voltage corresponding to each commutation process under a single-phase fault corresponding to different fault degrees, and obtain amplitude drop data and phase shift data;

[0126] The first analysis module 103 is used to analyze each commutation process according to the amplitude drop data and the phase offset data to determine the commutation process with a high risk of commutation failure and the commutation process with a low risk of commutation failure when a single-phase fault occurs;

[0127] The second analysis module 104 is used to analyze the control method of the high voltage direct current transmission system to obtain an advance triggering amount;

[0128] The suppression module 105 is used to detect the commutation process of the target high-voltage direct current transmission system through the control system, obtain the detection result, and issue a corresponding control signal based on the detection result to suppress the commutation failure of the target high-voltage direct current transmission system;

[0129] When the detection result is a commutation process with a high risk of commutation failure, the advance triggering amount is controlled by a control signal to suppress the commutation failure of the target HVDC transmission system;

[0130] When the detection result is a commutation process with a low risk of commutation failure, the control signal is used to stop or remove the advance trigger amount to suppress the commutation failure of the target high-voltage direct current transmission system.

[0131] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0132] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0133] The embodiment of the present invention also provides a terminal device, such as Fig.10 As shown, the terminal device D10 of this embodiment includes: at least one processor D100 ( Fig.10 Only one processor is shown in the figure), a memory D101, and a computer program D102 stored in the memory D101 and executable on the at least one processor D100. When the processor D100 executes the computer program D102, the method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault is implemented.

[0134] The terminal device D10 may be a computing device such as a desktop computer, a notebook, a PDA, a server, a server cluster, a cloud server, etc. The terminal device may include, but is not limited to, a processor D100 and a memory D101. Those skilled in the art will appreciate that Fig.10 This is only an example of the terminal device D10 and does not constitute a limitation on the terminal device D10. The terminal device D10 may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, it may also include input and output devices, network access devices, etc.

[0135] The processor D100 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0136] In some embodiments, the memory D101 may be an internal storage unit of the terminal device D10, such as a hard disk or memory of the terminal device D10. In other embodiments, the memory D101 may also be an external storage device of the terminal device D10, such as a plug-in hard disk, a smart memory card (SMC, SmartMedia Card), a secure digital (SD, Secure Digital) card, a flash card (Flash Card), etc. equipped on the terminal device D10. Further, the memory D101 may also include both an internal storage unit of the terminal device D10 and an external storage device. The memory D101 is used to store an operating system, an application program, a boot loader (BootLoader), data, and other programs, such as the program code of the computer program, etc. The memory D101 may also be used to temporarily store data that has been output or is to be output.

[0137] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0138] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0139] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, a method for suppressing commutation failure of high-voltage direct current transmission under a single-phase fault is implemented.

[0140] If 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 present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program code to the construction device / terminal device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), electric carrier signal, telecommunication signal and software distribution medium. For example, a USB flash drive, a mobile hard disk, a disk or an optical disk.

[0141] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault, characterized in that: Applied to high voltage DC transmission systems, including: Step 1, dividing each commutation process within one cycle of the inverter side in the high voltage direct current transmission system, and determining the commutation voltage corresponding to each commutation process; Step 2, for the commutation voltage corresponding to each commutation process, calculate the amplitude drop and phase shift of the commutation voltage corresponding to different fault degrees under a single-phase fault, and obtain amplitude drop data and phase shift data; Step 3, analyzing each commutation process according to the amplitude drop data and the phase shift data, and determining a commutation process with a high risk of commutation failure and a commutation process with a low risk of commutation failure when a single-phase fault occurs; Step 4: Analyze the control method of the high voltage direct current transmission system to obtain an advance trigger amount, and the calculation expression of the advance trigger amount is: ； in, ； In the formula, Indicates the advance trigger amount, represents the proportionality coefficient, represents the initial trigger angle, represents the trigger angle, represents the direct current, represents the amplitude of the commutation voltage, represents the reference turn-off angle, represents the phase advance angle, Indicates the commutation duration; Step 5, detecting the commutation process of the target high voltage direct current power transmission system through the control system to obtain a detection result, and issuing a corresponding control signal based on the detection result to suppress the commutation failure of the target high voltage direct current power transmission system; When the detection result is a commutation process with a high risk of commutation failure, the advance triggering amount is controlled by the control signal to suppress the commutation failure of the target high voltage direct current transmission system; When the detection result is a commutation process with a low risk of commutation failure, the advance triggering amount is stopped or removed through the control signal to suppress the commutation failure of the target high voltage direct current transmission system.

2. The method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault according to claim 1, characterized in that: The calculation expressions of the amplitude drop data and the phase shift data are as follows: in, Indicates the amplitude drop data, Indicates the commutation voltage amplitude during a fault. Indicates the rated amplitude of the commutation voltage, represents the phase offset data, represents the commutation process, , represents the initial phase of the commutation voltage at the time of fault, Indicates the initial phase of the commutation voltage under normal operating conditions.

3. The method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault according to claim 2 is characterized in that: The step 3 comprises: Calculate the turn-off angle of each commutation process according to the amplitude drop data and the phase shift data; A commutation process with a high risk of commutation failure and a commutation process with a low risk of commutation failure are determined according to the turn-off angle when a single-phase fault occurs.

4. The method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault according to claim 3 is characterized in that: The calculation expression of the turn-off angle of each commutation process is: in, represents the cut-off angle, represents the equivalent commutation inductance, Indicates the DC current rating, Represents the firing angle in steady state.

5. The method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault according to claim 4 is characterized in that: After step 5, it also includes: The commutation failure immunity factor is used to characterize the ability to suppress the commutation failure of the target high voltage direct current transmission system. The calculation expression of the commutation failure immunity factor is: ； in, Indicates phase failure immune factor, represents the critical fault power, Indicates the DC rated power, Indicates the rated voltage of the AC bus. Indicates the critical impedance of commutation failure.

6. A device for suppressing commutation failure of high-voltage direct current transmission under single-phase fault, characterized in that: Applied to high voltage DC transmission systems, including: A division module, used for dividing each commutation process within one cycle of the inverter side in the high voltage direct current transmission system, and determining the commutation voltage corresponding to each commutation process; A calculation module is used to calculate the amplitude drop and phase shift of the commutation voltage corresponding to each commutation process under a single-phase fault and corresponding to different fault degrees, and obtain amplitude drop data and phase shift data; A first analysis module is used to analyze each commutation process according to the amplitude drop data and the phase offset data to determine a commutation process with a high risk of commutation failure and a commutation process with a low risk of commutation failure when a single-phase fault occurs; The second analysis module is used to analyze the control method of the high voltage direct current transmission system to obtain an advance trigger amount, and the calculation expression of the advance trigger amount is: in, ； In the formula, Indicates the advance trigger amount, represents the proportionality coefficient, represents the initial trigger angle, represents the trigger angle, represents the direct current, represents the amplitude of the commutation voltage, represents the reference turn-off angle, represents the phase advance angle, Indicates the commutation duration; A suppression module, configured to detect a commutation process of a target high voltage direct current power transmission system through a control system, obtain a detection result, and issue a corresponding control signal based on the detection result to suppress commutation failure of the target high voltage direct current power transmission system; When the detection result is a commutation process with a high risk of commutation failure, the advance triggering amount is controlled by the control signal to suppress the commutation failure of the target high voltage direct current transmission system; When the detection result is a commutation process with a low risk of commutation failure, the advance triggering amount is stopped or removed through the control signal to suppress the commutation failure of the target high voltage direct current transmission system.

7. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault according to any one of claims 1 to 5 is implemented.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for suppressing commutation failure of high-voltage direct current transmission under single-phase fault as described in any one of claims 1 to 5 is implemented.

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