Method and system for identifying fault direction of ac line outlet in vicinity of inverter station and medium

Abstract

This invention discloses a method, system, and medium for determining the direction of faults at the outlet of AC lines near an inverter station, belonging to the field of power system relay protection. It includes: S1, constructing an equivalent electromagnetic transient calculation circuit model to solve for the AC boundary element current, obtaining the iterative relationship of the AC boundary element current at different times; S2, when a fault occurs, collecting voltage and current measurements at the protection installation location; S3, using the voltage and current measurements to calculate the AC boundary element current at a certain time before the fault occurs, and based on the iterative relationship, obtaining the time-domain change Δi of the AC boundary element current within a preset time after the fault occurs. b And calculate the time-domain change Δi of the line current measured within a preset time after the fault occurs. m S4. Calculate Δi b With Δi m S5. Determine the direction of the fault at the output based on the magnitude of the waveform similarity coefficient and the setting value. This invention enables reliable determination of the direction of an AC line output fault.

Description

Technical Field

[0001] This invention belongs to the field of power system relay protection, and more specifically, relates to a method, system and medium for determining the direction of AC line outlet faults near inverter stations based on waveform similarity coefficients. Background Technology

[0002] When a fault occurs in the AC line near the inverter station, the AC voltage drops, potentially causing commutation failure at the inverter station. This leads to output distortion and adversely affects the performance of relay protection. Directional elements are crucial components of longitudinal directional protection and distance protection; accurately identifying the fault direction is a prerequisite for reliable operation of these systems. However, when a short-circuit fault occurs near the line outlet, the measured voltage at the protection installation point is very low, making fault direction identification difficult. Failure to promptly determine the fault direction and clear the fault may damage the converter station equipment and jeopardize the safe and stable operation of the power system.

[0003] In the study of the fault direction discrimination principle of AC lines in the near area of ​​inverter station, when the AC outgoing line of inverter station is a single circuit, the directional element based on power frequency phasor will be affected by the commutation failure of inverter station and will be difficult to accurately judge the fault direction, and may even cause false operation or failure to operate. If traditional directional elements are still used, it is difficult to quickly and accurately judge the fault direction when the inverter station has only a single outgoing line. Summary of the Invention

[0004] To address the shortcomings and improvement needs of existing technologies, this invention provides a method, system, and medium for determining the direction of faults at the outlet of AC lines near inverter stations, with the aim of improving the accuracy of determining the direction of faults at the outlet of AC lines near inverter stations.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for determining the direction of faults at the outlet of an AC line near an inverter station is provided. An AC boundary element is connected to the converter bus on the inverter station side. The AC boundary element includes an AC filter and a reactive power compensation device. The fault direction determination method includes:

[0006] S1. Construct an equivalent electromagnetic transient calculation circuit model to solve the AC boundary element current, and obtain the iterative relationship of the AC boundary element current at different times.

[0007] S2. When a fault occurs, collect the voltage and current measurements at the protection installation location;

[0008] S3. Calculate the AC boundary element current at a certain moment before the fault occurs using the voltage and current measurements. Based on the iterative relationship, obtain the time-domain change Δi of the AC boundary element current within a preset time after the fault occurs. b; and calculate the time-domain change Δi of the AC current in the near-zone of the inverter station within a preset time after the fault occurs. m ;

[0009] S4. Calculate the time-domain change of the current Δi b With the time-domain change of the current Δi m The waveform similarity coefficient r(Δi) between m ,Δi b );

[0010] S5. Based on the waveform similarity coefficient r(Δi) m ,Δi b ) and the setpoint r set The magnitude of the difference determines the direction of the exit fault.

[0011] Further, in S1, constructing an equivalent electromagnetic transient calculation circuit model for solving the current of the AC boundary element includes:

[0012] S1.1 The function of all active branches connected to the converter bus on the inverter station side is equivalent to an equivalent voltage source, and the equivalent voltage source and the AC boundary element form a series circuit;

[0013] S1.2. The inductor and capacitor elements in the AC boundary elements of the series circuit are all equivalent to the structure of a resistor and a current source connected in parallel, thus obtaining the equivalent electromagnetic transient calculation circuit model.

[0014] Furthermore, in S1.1, the function of the active branch includes the function of the DC-side converter station and the function of the AC power supply.

[0015] Furthermore, in S1.2, the implicit trapezoidal integral method is used to treat the inductor and capacitor elements in the AC boundary elements of the series circuit as equivalent to a structure in parallel between a resistor and a current source.

[0016] Furthermore, in step S5, if the waveform similarity coefficient r(Δi) m ,Δi b () less than or equal to the set value r set If the condition is met, a forward exit failure has occurred; otherwise, a reverse exit failure has occurred.

[0017] Furthermore, in S3, the moment before the fault occurs is the zero-crossing point of the converter bus voltage two cycles before the fault.

[0018] Furthermore, in S2, when a fault occurs, the faulty phase is determined according to the phase selection criteria, and the voltage and current measured at the protection installation point corresponding to the fault are collected;

[0019] In step S3, the time-domain change Δi of the current in the faulty phase measured on the AC line near the inverter station within a preset time after the fault occurs is calculated. m .

[0020] Furthermore, in S4, the waveform similarity coefficient r(Δi) m ,Δi b )for:

[0021]

[0022] Where, Δi m (i), Δi b (i) represents the time-domain change of the current Δi m and the time-domain change of the current Δi b The sampled value at time i, where N is the length of the data window used to calculate the waveform similarity coefficient.

[0023] According to a second aspect of the present invention, a fault direction discrimination system for near-zone AC line outlet of an inverter station is provided, wherein an AC boundary element is connected to the converter bus on the inverter station side, the AC boundary element including an AC filter and a reactive power compensation device, and the fault direction discrimination system method includes:

[0024] The iterative relationship construction module is used to construct an equivalent electromagnetic transient calculation circuit model for solving the AC boundary element current, and obtain the iterative relationship of the AC boundary element current at different times.

[0025] The line electrical quantity acquisition module is used to collect voltage and current measurements at the protection installation location when a fault occurs.

[0026] The current time-domain change calculation module is used to calculate the AC boundary element current at a certain moment before the fault occurs using the voltage and current measured at the protection installation point, and based on the iterative relationship, obtain the time-domain change Δi of the AC boundary element current within a preset time after the fault occurs. b ; and calculate the time-domain change Δi of the AC current in the near-zone of the inverter station within a preset time after the fault occurs. m ;

[0027] The waveform similarity coefficient calculation module is used to calculate the time-domain change Δi of the current. b With the time-domain change of the current Δi m The waveform similarity coefficient r(Δi) between m ,Δi b );

[0028] The fault direction determination module is used to determine the fault direction based on the waveform similarity coefficient r(Δi). m ,Δi b ) and the setpoint r setThe magnitude of the difference determines the direction of the exit fault.

[0029] According to a third aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the fault direction determination method as described in any one of the first aspects.

[0030] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0031] (1) The method and system for determining the direction of AC line outlet faults in the near-zone of an inverter station based on waveform similarity coefficient of the present invention obtains the iterative relationship of AC boundary element currents at different times by constructing an equivalent electromagnetic transient calculation circuit model for solving AC boundary element currents, and using AC line measured voltage and current to calculate the current on AC boundary elements when and after the fault occurs. The direction of the line outlet fault is determined by comparing the waveform similarity coefficient between the AC line current and the AC boundary element current under the fault and the setting value. The method of the present invention has simple criteria and is independent of whether the inverter station commutation fails. It can reliably and sensitively determine the direction of the outlet fault of AC lines in the near-zone of an inverter station.

[0032] (2) As a preferred option, a certain moment before the fault occurs is set as the zero-crossing point of the converter bus voltage two cycles before the fault. At this time, the energy stored in the dynamic elements of the AC boundary elements is low. Since the converter bus voltage used in the iteration is an accurate measurement value, the iteration accuracy error caused by setting the equivalent current source in the equivalent electromagnetic transient calculation circuit model to zero will be eliminated in a very short time. The calculated AC boundary element current can meet the accuracy requirements of the protection and reduce the amount of calculation. Attached Figure Description

[0033] Figure 1 This is a flowchart of the fault direction determination method provided in the embodiments of the present invention;

[0034] Figure 2 This is a schematic diagram of an AC / DC hybrid system model provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the location of the AC line outlet in the near-zone of the inverter station provided in an embodiment of the present invention;

[0036] Figure 4(a) is a schematic diagram of the waveform similarity coefficient between the time-domain change of the AC boundary element current at point M of the protection system and the time-domain change of the measured line current when there is a phase-A ground fault.

[0037] Figure 4(b) is a schematic diagram of the waveform similarity coefficient between the time-domain change of the AC boundary element current at point M of the protection system and the time-domain change of the measured line current when the two phases BC are short-circuited.

[0038] Figure 5(a) is a schematic diagram of the waveform similarity coefficient between the time-domain change of the AC boundary element current at protection point M and the time-domain change of the line measured current when a fault occurs at time 0.692s.

[0039] Figure 5(b) is a schematic diagram of the waveform similarity coefficient between the time-domain change of the AC boundary element current at protection point M and the time-domain change of the line measured current when a fault occurs at time 0.698s. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0041] like Figures 1-3 As shown, the present invention provides a method for determining the fault direction of the AC line outlet in the near-zone of an inverter station based on waveform similarity coefficient. This method is applied to a DC-DC hybrid system, which includes a sending-end AC system, a converter station system consisting of a rectifier station and an inverter station, a DC line, an AC line, a receiving-end AC system, an AC filter, and a reactive power compensation device. The sending-end AC system transmits power to the receiving-end AC system via the converter station system and the DC line. The inverter station outlet is connected to the receiving-end AC system via the near-zone AC line. The AC filter and reactive power compensation device are connected to the converter bus. The AC filter and reactive power compensation device connected to the converter bus on the inverter side are collectively referred to as AC boundary elements.

[0042] The fault direction determination method of the present invention mainly includes the following steps:

[0043] S1. Construct an equivalent electromagnetic transient calculation circuit model to solve the AC boundary element current, and obtain the iterative relationship of the AC boundary element current at different times.

[0044] S2. When a short-circuit fault occurs on the protected AC line, record the time of the fault occurrence; and determine the faulty phase according to the phase selection criteria, and collect the voltage and current measurement values ​​at the protection installation point corresponding to the fault.

[0045] S3. Calculate the AC boundary element current at a certain moment before the fault occurs using the voltage and current measurements from the protection device. Based on the iterative relationship between the AC boundary element currents at different times, calculate the time-domain change Δi of the AC boundary element current within a preset time after the fault occurs. b And calculate the time-domain change Δi of the corresponding fault current measured on both sides of the AC line near the inverter station within a preset time after the fault occurs. m ;

[0046] S4. Calculate the time-domain change Δi of the AC boundary element current. b The time-domain change of current Δi corresponding to different faults measured on both sides of the AC line near the inverter station m The waveform similarity coefficient r(Δi) between m ,Δi b );

[0047] S5. Based on the waveform similarity coefficient r(Δi) m ,Δi b ) and the setpoint r set The relative sizes of the two parts determine the direction of the exit fault.

[0048] Specifically, in step S1, the method for constructing an equivalent electromagnetic transient calculation circuit model for solving the AC boundary element current includes:

[0049] S1.1. The function of all active branches connected to the inverter bus of the inverter station is unified and equivalent to an equivalent voltage source. The equivalent voltage source and the AC boundary element form a series circuit.

[0050] S1.2. In the series circuit, the inductors and capacitors in the AC boundary elements are all equivalent to the structure of resistors and current sources in parallel. That is, each inductor is equivalent to the structure of resistors and current sources in parallel, and each capacitor is equivalent to the structure of resistors and current sources in parallel, so as to obtain the equivalent electromagnetic transient calculation circuit model.

[0051] In step S1.1, the functions of all active branches connected to the inverter bus include the function of the DC-side converter station and the function of the AC power supply.

[0052] In step S1.2, the implicit trapezoidal integration method is used to treat the inductors and capacitors in the AC boundary elements of the series circuit as equivalent to a structure in parallel between a resistor and a current source.

[0053] By using an iterative approach, the circuit state at any given moment is calculated using an equivalent electromagnetic transient calculation circuit model and initial state. The voltage at any node and the current in any branch of the entire circuit are obtained, and then the AC boundary element current is calculated.

[0054] In this invention, by using the node voltage analysis method, a certain moment before the fault is selected as the initial moment of iteration, and the fault occurrence time and the AC boundary element current after the fault can be calculated iteratively.

[0055] The initial iteration time is a point in time before the fault, which can be determined according to actual needs. As a preferred method, considering both the accuracy and speed of the iteration, the initial iteration time can be set to the zero-crossing point of the converter bus voltage two cycles before the fault, based on actual requirements. At this time, the energy stored in the dynamic elements of the AC boundary element is low. Since the converter bus voltage used in the iteration is an accurate measurement, the iteration accuracy error caused by setting the equivalent current source (i.e., the current source after the inductance and capacitance elements in the AC boundary element) to zero will be eliminated in a very short time. The calculated AC boundary element current can meet the accuracy requirements of the protection and reduce the amount of calculation.

[0056] Specifically, in step S3, the time-domain change of current is defined. Let t be the current. The instantaneous value of the current and the instantaneous value of the current before the preset time T The difference, that is:

[0057]

[0058] The time-domain change Δi of the AC boundary element current within a preset time after the fault occurs. b for:

[0059] Δi b (t)=i b (t)-i b (t-T1)

[0060] Where t-T1 represents the time when the fault occurs, and T1 is the preset time after the fault occurs.

[0061] The time-domain change Δi of the current corresponding to different faults measured on both sides of the AC line near the inverter station within a preset time after the fault occurs. m for:

[0062] Δi m (t)=i m (t)-i m (t-T1)

[0063] Different currents i are used for different short-circuit faults. m (t), for a single-phase short-circuit ground fault, the current used is the fault phase current; for a two-phase short-circuit fault and a two-phase short-circuit ground fault, the current used is the difference between the fault phase currents; for a three-phase short-circuit fault, the current used is the current of one of the phases.

[0064] Specifically, in step S4, the waveform similarity coefficient r(Δi) m ,Δi b )for:

[0065]

[0066] Where, Δi m (i), Δi b (i) represents the sampled values ​​of the time-domain changes of current and the time-domain changes of current of AC boundary elements corresponding to different faults measured on both sides of the AC line at time i, respectively, and N is the data window length for calculating the waveform similarity coefficient.

[0067] Specifically, in step S5, if the waveform similarity coefficient r(Δi) m ,Δi b Less than or equal to the set value r set If so, it is considered that a positive exit failure has occurred;

[0068] If the waveform similarity coefficient r(Δi) m ,Δi b () greater than the set value r set If so, it is considered that a reverse exit failure has occurred.

[0069] The criterion for a positive exit failure is:

[0070] r(Δi m ,Δi b )≤r set

[0071] The criterion for failure at the reverse exit is:

[0072] r(Δi m ,Δi b )>r set

[0073] To further illustrate the method for determining the direction of AC line outlet faults near inverter stations based on waveform similarity coefficients provided in this invention, the following detailed description is provided in conjunction with the accompanying drawings and specific examples:

[0074] Build in PSCAD / EMTDC, such as Figure 2 The AC / DC hybrid system shown is used as an example for illustration.

[0075] The DC hybrid system includes a sending-end AC system, a converter station system consisting of a rectifier station and an inverter station, DC lines, AC lines, a receiving-end AC system, AC filters, and reactive power compensation devices. The sending-end AC system transmits power to the receiving-end AC system through the converter station system and DC lines. The inverter station outlet is connected to the receiving-end AC system through the near-zone AC lines. The AC filters and reactive power compensation devices are connected to the converter bus.

[0076] The AC filter and reactive power compensation device connected to the inverter-side converter bus are collectively referred to as AC boundary elements.

[0077] Two 6-pulse converters are connected in series on the DC side of the rectifier station model, and connected in parallel to the converter bus on the AC side via a Y / Y converter transformer and a Y / Δ converter transformer;

[0078] An exit fault is set on the AC line in the vicinity of the inverter station. The location of the exit fault on the AC line in the vicinity of the inverter station is as follows: Figure 3 As shown.

[0079] The above-mentioned method for determining the direction of AC line outlet faults near inverter stations based on waveform similarity coefficients is used.

[0080] In this embodiment, the following settings are provided: Figure 2 F1 and F2 represent the forward and reverse fault outputs at protection point M, respectively. Different types of faults are set at F1 and F2, including phase A grounding and phase BC short circuit, denoted as AG and BC, respectively. In this embodiment, the waveform similarity coefficient setting is set to 0.25.

[0081] Since the interval between two commutation processes of a 12-pulse converter during normal operation is 30°, or 1.67ms, and considering that the protection principle itself is based on time-domain analysis, in order to minimize the impact of changes in the inverter-side current on the protection principle, in this embodiment, the proposed protection principle is only activated within 1ms after a fault.

[0082] Figures 4(a) and 4(b) show the waveform similarity coefficients of the time-domain change of the AC boundary element current at protection point M and the time-domain change of the line measured current when the fault occurs at F1 and F2 respectively at 0.69s and AG and BC faults are set. Figures 5(a) and 5(b) show the waveform similarity coefficients of the AC line measured current change and the AC boundary element current change at protection point M at F1 and F2 respectively at 0.692s and 0.698s and AG faults are set. For AG faults, the current change is the change of phase A current; for BC faults, the current change is the change of the difference between phase B and C currents.

[0083] As shown in Figures 4(a) and 4(b), for a positive-direction outlet fault (F1), the waveform similarity coefficients of the AC line measured current change and the AC boundary element current change at protection point M are near 0 after the fault. At this time, the calculated correlation coefficient r(Δi) m ,Δi b All of them are less than the set value of 0.25, which meets the positive fault criterion for the outlet and is judged as a positive fault; for the reverse outlet fault (F2), the waveform similarity coefficient has been maintained at around 1, showing a large degree of dissimilarity, and is judged as a reverse fault.

[0084] As shown in Figures 5(a) and 5(b), at different fault times, for a positive-direction outlet fault (F1), the waveform similarity coefficients of the AC line measured current change and the AC boundary element current change at protection M are near 0 after the fault. At this time, the calculated correlation coefficient r(Δi) m ,Δi b All of them are less than the set value of 0.25, which meets the positive exit fault criterion and is judged as a positive fault; for the reverse exit fault (F2), the waveform similarity coefficient is greater than the set value of 0.25, showing a large degree of dissimilarity and is judged as a reverse fault.

[0085] The method provided in this invention can accurately and reliably determine the direction of a fault under different fault types and at different fault times.

[0086] This invention also provides a fault direction discrimination system for AC line outlets near inverter stations based on waveform similarity coefficients. An AC boundary element is connected to the converter bus on the inverter station side. The AC boundary element includes an AC filter and a reactive power compensation device. This discrimination system is used to implement the specific steps of the aforementioned fault direction discrimination method for AC line outlets near inverter stations based on waveform similarity coefficients, mainly including:

[0087] The iterative relationship construction module is used to construct an equivalent electromagnetic transient calculation circuit model for solving the AC boundary element current, and obtain the iterative relationship of the AC boundary element current at different time points;

[0088] The line electrical quantity acquisition module is used to record the time of fault occurrence and collect voltage and current measurement values ​​at the protection installation location when a fault occurs.

[0089] The current time-domain change calculation module is used to calculate the AC boundary element current at a certain moment before the fault occurs using the voltage and current measurements at the protection installation point. Based on the iterative relationship, it obtains the AC boundary element current time-domain change Δi within a preset time after the fault occurs. b ; and calculate the time-domain change Δi of the current measured on the AC line near the inverter station within a preset time after the fault occurs. m ;

[0090] The waveform similarity coefficient calculation module is used to calculate the time-domain change in current Δi. b With the time-domain change of current Δi m The waveform similarity coefficient r(Δi) between m ,Δi b );

[0091] The fault direction determination module is used to determine the fault direction based on the waveform similarity coefficient r(Δi). m ,Δi b ) and the setpoint r setThe magnitude of the difference determines the direction of the exit fault.

[0092] For details on the implementation of each module, please refer to the corresponding implementation steps in the fault direction determination method described above.

[0093] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the various steps of the fault direction determination method described above.

[0094] The present invention provides a method for determining the direction of AC line outlet faults near inverter stations based on waveform similarity coefficients. This method constructs an equivalent electromagnetic transient calculation circuit model to solve for the AC boundary element current, obtaining the iterative relationship between the AC boundary element currents at different times. It uses measured voltage and current of the AC line to calculate the current on the AC boundary elements at and after the fault. By comparing the waveform similarity coefficient between the AC line current and the time-domain change of the AC boundary element current under fault conditions with the set value, the direction of the line outlet fault is determined. This method has simple criteria and is independent of whether the inverter station commutation has failed. It can reliably and sensitively determine the direction of outlet faults for AC lines near inverter stations, effectively solving the problem that the power frequency change direction element is no longer applicable when the inverter station's AC outgoing line is a single-circuit line.

[0095] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the direction of faults at the outlet of an AC line near an inverter station, wherein an AC boundary element is connected to the converter bus on the inverter station side, the AC boundary element comprising an AC filter and a reactive power compensation device, characterized in that... The fault direction determination method includes: S1. Construct an equivalent electromagnetic transient calculation circuit model to solve the AC boundary element current, and obtain the iterative relationship of the AC boundary element current at different times. S2. When a fault occurs, collect the voltage and current measurements at the protection installation location; S3. Calculate the AC boundary element current at a certain moment before the fault occurs using the voltage and current measurements. Based on the iterative relationship, obtain the time-domain change of the AC boundary element current within a preset time after the fault occurs. i b ; and calculate the time-domain change of current in the AC lines near the inverter station within a preset time after the fault occurs. i m ; S4. Calculate the time-domain change of the current. i b With the time-domain change of the current i m Waveform similarity coefficient between r ( i m , i b ); S5. Based on the waveform similarity coefficient r ( i m , i b ) and setting value r set The magnitude of the difference between the two values ​​determines the direction of the exit fault; wherein, if the waveform similarity coefficient... r ( i m , i b () less than or equal to the set value r set If the condition is met, a forward exit failure has occurred; otherwise, a reverse exit failure has occurred. In S4, the waveform similarity coefficient r ( i m , i b )for: in, , These are the time-domain changes of the current, respectively. i m and the time-domain variation of the current i b In the i The sampled value at time 10:

00. N The length of the data window used to calculate the waveform similarity coefficient.

2. The fault direction determination method according to claim 1, characterized in that, In step S1, an equivalent electromagnetic transient calculation circuit model for solving the current of the AC boundary element is constructed, including: S1.1 The function of all active branches connected to the converter bus on the inverter station side is equivalent to an equivalent voltage source, and the equivalent voltage source and the AC boundary element form a series circuit; S1.

2. The inductor and capacitor elements in the AC boundary elements of the series circuit are all equivalent to the structure of a resistor and a current source connected in parallel, thus obtaining the equivalent electromagnetic transient calculation circuit model.

3. The fault direction determination method according to claim 2, characterized in that, In S1.1, the function of the active branch includes the function of the DC-side converter station and the function of the AC power supply.

4. The fault direction determination method according to claim 2, characterized in that, In S1.2, the implicit trapezoidal integral method is used to treat the inductor and capacitor elements in the AC boundary elements of the series circuit as equivalent to a structure in parallel between a resistor and a current source.

5. The fault direction determination method according to claim 1, characterized in that, In S3, the moment before the fault occurs is the zero-crossing point of the converter bus voltage two cycles before the fault.

6. The fault direction determination method according to claim 1, characterized in that, In S2, when a fault occurs, the faulty phase is determined according to the phase selection criteria, and the voltage and current measured at the protection installation point corresponding to the fault are collected. In step S3, the time-domain change of the current of the faulted phase measured on the AC line near the inverter station within a preset time after the fault occurs is calculated. i m .

7. A fault direction determination system for near-zone AC line outlet of an inverter station, wherein an AC boundary element is connected to the converter bus on the inverter station side, the AC boundary element comprising an AC filter and a reactive power compensation device, characterized in that, The fault direction discrimination system method includes: The iterative relationship construction module is used to construct an equivalent electromagnetic transient calculation circuit model for solving the AC boundary element current, and obtain the iterative relationship of the AC boundary element current at different times. The line electrical quantity acquisition module is used to collect voltage and current measurements at the protection installation location when a fault occurs. The current time-domain change calculation module is used to calculate the AC boundary element current at a certain moment before the fault occurs using the voltage measurement value and the current measurement value, and based on the iterative relationship, obtain the time-domain change of the AC boundary element current within a preset time after the fault occurs. i b ; and calculate the time-domain change of current in the AC lines near the inverter station within a preset time after the fault occurs. i m ; The waveform similarity coefficient calculation module is used to calculate the time-domain change of the current. i b With the time-domain change of the current i m Waveform similarity coefficient between r ( i m , i b ); The fault direction determination module is used to determine the fault direction based on the waveform similarity coefficient. r ( i m , i b ) and setting value r set The magnitude of the difference between the two values ​​determines the direction of the exit fault; wherein, if the waveform similarity coefficient... r ( i m , i b () less than or equal to the set value r set If the condition is met, a forward exit failure has occurred; otherwise, a reverse exit failure has occurred. In the waveform similarity coefficient calculation module, the waveform similarity coefficient r ( i m , i b )for: in, , These are the time-domain changes of the current, respectively. i m and the time-domain variation of the current i b In the i The sampled value at time 10:

00. N The length of the data window used to calculate the waveform similarity coefficient.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the fault direction determination method as described in any one of claims 1-6.

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