Method and device for identifying lightning stroke disturbance of multi-terminal flexible direct current power transmission system

Abstract

The invention discloses a method and a device for identifying lightning disturbance of a multi-terminal flexible direct-current power transmission system. The method comprises the following steps: acquiring a voltage instantaneous value of a direct-current line; obtaining a line mode voltage difference of the DC line based on the voltage instantaneous value of the DC line; based on the line mode voltage difference, obtaining a criterion action quantity and a progressive value sum; and judging whether the current working condition is lightning stroke disturbance or not based on the line mode voltage difference, the criterion action quantity and the progressive value sum. According to the method and the device provided by the embodiment of the invention, the lightning stroke disturbance can be accurately identified in a multi-section flexible direct-current power transmission system scene in which the current limiting equipment is arranged at the outlet of the converter station, so that the problem of line protection misoperation possibly caused by the lightning stroke disturbance is solved.

Description

Technical Field

[0001] This invention relates to the field of relay protection technology, and more specifically, to a method and apparatus for identifying lightning disturbances in a multi-terminal flexible DC transmission system. Background Technology

[0002] For flexible DC transmission systems, especially radial multi-terminal flexible DC transmission systems, effective fault current limiting capability at the moment of a fault can limit the development speed of DC faults, thereby reducing the requirements for fault interruption speed. This reliably protects the flexible DC system by avoiding or reducing damage from fault impacts. Configuring appropriate current limiting devices can limit and maintain the extremely large amplitude and rise rate of DC fault currents within an acceptable range after a fault occurs, thus reducing the requirements for interruption capacity and fault clearing time of DC circuit breakers.

[0003] The installation location of current limiting devices is currently a focus of discussion. In general, while adding boundary elements is beneficial for protection scheme design, it increases costs. While reactors at both ends of the line limit the rate of rise of fault current, they also prolong fault clearing time, negatively impacting the dynamic and safety performance of the DC system. From the perspective of improving system dynamic performance and economy, the scheme of installing reactors at the converter station outlet is more advantageous.

[0004] Lightning disturbances are a common form of disturbance in power systems. When a lightning disturbance occurs, it can develop in various ways depending on the location of the lightning strike and whether it causes a fault. Among them, "flanking" disturbances, where lightning bypasses the surge arrester and strikes the line directly, are one of the main disturbance modes that cause line protection maloperation due to their similarity to fault characteristics. In engineering, standard double-exponential lightning waves are usually used to simulate the lightning waves generated by lightning strikes. The lightning waves generated by lightning disturbances are quite similar to impulse responses in terms of waveform characteristics, with large peaks and extremely short durations. This makes it easy for the lightning waves to be buffered and absorbed when passing through current-limiting devices. Therefore, in traditional flexible DC transmission systems, the impact on protection performance is limited. However, in multi-segment flexible DC transmission systems where current-limiting devices are installed at the converter station outlet, lightning disturbances can affect line protection without being buffered by current-limiting devices, thus easily causing protection maloperation problems. Summary of the Invention

[0005] In view of this, the present invention proposes a method and apparatus for identifying lightning disturbances in a multi-terminal flexible DC transmission system, aiming to solve one or more of the technical problems mentioned in the background section above.

[0006] In a first aspect, embodiments of the present invention provide a method for identifying lightning disturbances in a multi-terminal flexible DC transmission system. The method includes: acquiring the instantaneous voltage value of a DC line; obtaining the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line; obtaining a criterion action quantity and an accumulated value sum based on the line-mode voltage difference; and determining whether the current operating condition is a lightning disturbance based on the line-mode voltage difference, the criterion action quantity, and the accumulated value sum.

[0007] Further, based on the instantaneous voltage value of the DC line, the line-mode voltage difference of the DC line is obtained, including: obtaining the line-mode voltage of the DC line based on the instantaneous voltage value of the DC line; and calculating the difference between the line-mode voltages of the DC line to obtain the line-mode voltage difference of the DC line.

[0008] Furthermore, the DC line includes a positive line and a negative line. Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained, which includes subtracting the instantaneous voltage values ​​of the positive line and the negative line and then dividing by 2 to obtain the line-mode voltage of the DC line.

[0009] Furthermore, the criterion action quantity is obtained as follows: the line-mode voltage difference is normalized to obtain a normalized value; the difference between the normalized values ​​is calculated to obtain a normalized value difference; the normalized value difference is multiplied by the line-mode voltage difference to obtain the criterion action quantity.

[0010] Furthermore, the cumulative value is obtained as follows: the cumulative value P is defined by the following formula. M (t), define P separately M (t0-1)=0:

[0011]

[0012] Where t is the time of adoption, and t0 is the initial time of adoption. Line-mode voltage differential;

[0013] Summing the cumulative values, we get the following cumulative sum:

[0014]

[0015] Further, based on the line-mode voltage difference, the criterion action amount, and the cumulative sum, determining whether the current operating condition is a lightning disturbance includes: if the criterion action amount is greater than a preset braking amount, then it is determined that a traveling wave front has been detected; if a traveling wave front is detected, then the polarity of the traveling wave front is determined based on the line-mode voltage difference; if a traveling wave front is detected simultaneously at the current time and the next time, and the polarities of the traveling wave fronts are inconsistent, then the current operating condition is determined to be a suspected lightning strike; if the current operating condition is a suspected lightning strike, and the cumulative sum is not less than a preset threshold, then the current operating condition is determined to be a lightning disturbance.

[0016] Furthermore, based on the line-mode voltage difference, the polarity of the traveling wave front is determined, including: if the line-mode voltage difference is greater than or equal to 0, the polarity of the traveling wave front is determined to be negative; otherwise, it is positive.

[0017] Secondly, embodiments of the present invention also provide a device for identifying lightning disturbances in a multi-terminal flexible DC transmission system. The device includes: an acquisition unit for acquiring the instantaneous voltage value of a DC line; a first processing unit for obtaining the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line; a second processing unit for obtaining a criterion action quantity and an accumulated value sum based on the line-mode voltage difference; and a determination unit for determining whether the current operating condition is a lightning disturbance based on the line-mode voltage difference, the criterion action quantity, and the accumulated value sum.

[0018] Furthermore, the first processing unit is also configured to: obtain the line-mode voltage of the DC line based on the instantaneous voltage value of the DC line; and calculate the difference between the line-mode voltage of the DC line to obtain the line-mode voltage difference of the DC line.

[0019] Furthermore, the DC line includes a positive line and a negative line. Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained, which includes subtracting the instantaneous voltage values ​​of the positive line and the negative line and then dividing by 2 to obtain the line-mode voltage of the DC line.

[0020] Furthermore, the criterion action quantity is obtained as follows: the line-mode voltage difference is normalized to obtain a normalized value; the difference between the normalized values ​​is calculated to obtain a normalized value difference; the normalized value difference is multiplied by the line-mode voltage difference to obtain the criterion action quantity.

[0021] Furthermore, the cumulative value is obtained as follows: the cumulative value P is defined by the following formula. M (t), define P separately M (t0-1)=0:

[0022]

[0023] Where t is the time of adoption, and t0 is the initial time of adoption. Line-mode voltage differential;

[0024] Summing the cumulative values, we get the following cumulative sum:

[0025]

[0026] Furthermore, the determination unit is also configured to: determine that a traveling wave front is detected if the criterion action amount is greater than a preset braking amount; determine the polarity of the traveling wave front based on the line-mode voltage difference if a traveling wave front is detected; determine that the current operating condition is a suspected lightning strike if a traveling wave front is detected at the current time and the next time, and the polarities of the traveling wave fronts are inconsistent; determine that the current operating condition is a suspected lightning strike if the current operating condition is a suspected lightning strike and the cumulative value is not less than a preset threshold.

[0027] Furthermore, based on the line-mode voltage difference, the polarity of the traveling wave front is determined, including: if the line-mode voltage difference is greater than or equal to 0, the polarity of the traveling wave front is determined to be negative; otherwise, it is positive.

[0028] Thirdly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the methods provided in the above embodiments.

[0029] Fourthly, embodiments of the present invention also provide an electronic device, including: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the methods provided in the above embodiments.

[0030] The method and apparatus for identifying lightning disturbances in a multi-terminal flexible DC transmission system provided in this invention obtains the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line, and then obtains the criterion action quantity and cumulative value sum. Based on the line-mode voltage difference, the criterion action quantity and cumulative value sum, it determines whether the current operating condition is a lightning disturbance. This method can accurately identify lightning disturbances in multi-segment flexible DC transmission systems where current limiting equipment is installed at the converter station outlet, thereby solving the problem that lightning disturbances may cause line protection to malfunction. Attached Figure Description

[0031] Figure 1 An exemplary flowchart of a method for identifying lightning disturbances in a multi-terminal flexible DC transmission system according to an embodiment of the present invention is shown;

[0032] Figure 2 A schematic diagram of a multi-terminal flexible DC transmission system topology is shown according to an embodiment of the present invention;

[0033] Figures 3a-3c This diagram illustrates the operation result of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the midpoint of line l1 according to an embodiment of the present invention. Figure 3a , 3b Figures 3c and 3c represent the schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively.

[0034] Figures 4a-4c This diagram illustrates the operational results of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the midpoint of line l1 according to an embodiment of the present invention. Figure 4a , 4b Figures 4c and 4c represent schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively.

[0035] Figures 5a-5c This diagram illustrates the operational results of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the midpoint of line l2 according to an embodiment of the present invention. Figure 5a , 5b Figures 5c and 5c represent the schematic diagram of the line mode voltage waveform, the schematic diagram of the traveling wave front detection result, and the schematic diagram of the cumulative value and the cumulative value summation waveform, respectively.

[0036] Figures 6a-6c This diagram illustrates the operation result of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the midpoint of line l2 according to an embodiment of the present invention. Figure 6a , 6b Figures 6 and 6c represent schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively.

[0037] Figures 7a-7c This diagram illustrates the operation result of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the head end of line l1 according to an embodiment of the present invention. Figure 7a , 7b Figures 7 and 7c represent schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively.

[0038] Figures 8a-8c This diagram illustrates the operational results of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the head end of line l1 according to an embodiment of the present invention. Figure 8a , 8b Figures 8 and 8c represent schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively.

[0039] Figures 9a-9cThis diagram illustrates the operation result of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the end of line l1 according to an embodiment of the present invention. Figure 9a , 9b Figures 9 and 9c represent schematic diagrams of line mode voltage waveform, traveling wave front detection results, cumulative value, and cumulative value summation waveform, respectively.

[0040] Figures 10a-10c This diagram illustrates the operation result of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the end of line l1 according to an embodiment of the present invention. Figure 10a , 10b 10c represents the schematic diagram of the line mode voltage waveform, the schematic diagram of the traveling wave front detection result, and the schematic diagram of the cumulative value and the cumulative value summation waveform, respectively.

[0041] Figure 11 A schematic diagram of a device for identifying lightning disturbances in a multi-terminal flexible DC transmission system according to an embodiment of the present invention is shown. Detailed Implementation

[0042] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0043] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0044] Figure 1 An exemplary flowchart of a method for identifying lightning disturbances in a multi-terminal flexible DC transmission system according to an embodiment of the present invention is shown.

[0045] like Figure 1 As shown, the method includes:

[0046] Step S101: Obtain the instantaneous voltage value of the DC line.

[0047] Specifically, the instantaneous voltage value u measured on the M side of the DC line is obtained. p M (t), u n M (t), and the instantaneous voltage value u measured on the N side of the DC line.p N (t), u n N (t), where the superscripts p and n refer to the positive and negative terminals, respectively.

[0048] Step S102: Based on the instantaneous voltage value of the DC line, obtain the line-mode voltage difference of the DC line.

[0049] Further, step S102 includes:

[0050] The line-mode voltage of the DC line is obtained based on the instantaneous voltage value of the DC line.

[0051] The line-mode voltage difference of the DC line is obtained by calculating the difference between the line-mode voltages.

[0052] Furthermore, the DC line includes a positive line and a negative line. Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained, including:

[0053] The line-mode voltage of the DC line is obtained by subtracting the instantaneous voltage values ​​of the positive and negative lines and then dividing by 2.

[0054] Specifically, the line-mode voltage u measured on the M and N sides of the DC line 1 M (t), u 1 N (t) can be obtained by the following formula:

[0055]

[0056] The method is described below using the M-side as an example. The N-side criterion is constructed in the same way.

[0057] First, calculate the difference between the line-mode voltages on both sides of the DC line:

[0058]

[0059] Where t is the current sampling time.

[0060] Step S103: Based on the line-mode voltage difference, obtain the criterion action quantity and the cumulative value.

[0061] Furthermore, the criterion action quantity is obtained in the following way:

[0062] The line-mode voltage difference is normalized to obtain the normalized value;

[0063] The difference between the normalized values ​​is obtained by taking the difference between the normalized values.

[0064] Multiply the normalized numerical difference with the line-mode voltage difference to obtain the criterion action quantity.

[0065] Specifically, the line-mode voltage difference is normalized. To avoid the influence of subscripts and superscripts, this physical quantity is represented by the algebraic number B below:

[0066]

[0067] in, The absolute maximum value of the line-mode voltage on both sides from time t0 to time t.

[0068] Further research on B M (t) Find the difference:

[0069] B′ M (t)=B M (t)-B M (t-1)

[0070] At this point, the criterion action quantity can be calculated. Let the criterion action quantity be C(t), then:

[0071]

[0072] Furthermore, the cumulative sum is obtained as follows:

[0073] The cumulative value P is defined by the following formula. M (t), define P separately M (t0-1)=0:

[0074]

[0075] Where t is the time of adoption, and t0 is the initial time of adoption. Line-mode voltage differential;

[0076] Summing the cumulative values, we get the following cumulative sum:

[0077]

[0078] Specifically, starting from time t0 and ending at time t, the cumulative value P is defined by the following formula. M (t). Define P again. M (t0-1)=0.

[0079]

[0080] Summing the cumulative values, we get the following cumulative sum:

[0081]

[0082] Step S104: Based on the line-mode voltage difference, the criterion action quantity, and the cumulative value, determine whether the current operating condition is a lightning disturbance.

[0083] Further, step S104 includes:

[0084] If the criterion action amount is greater than the preset braking amount, it is determined that a traveling wave front has been detected.

[0085] If a traveling wave front is detected, the polarity of the traveling wave front is determined based on the line-mode voltage difference.

[0086] If a traveling wave front is detected simultaneously at the current moment and at the next moment, and the polarities of the traveling wave fronts are inconsistent, then the current working condition is determined to be a suspected lightning strike.

[0087] If the current operating condition is suspected to be a lightning strike, and the cumulative value is not less than the preset threshold, the current operating condition is determined to be a lightning strike disturbance.

[0088] Furthermore, based on the line-mode voltage difference, the polarity of the traveling wave front is determined, including:

[0089] If the line-mode voltage difference is greater than or equal to 0, the polarity of the traveling wave front is considered to be negative; otherwise, it is considered to be positive.

[0090] Specifically, when the criterion action quantity C(t) > C set At that time, it was determined that a traveling wave front had been detected. Braking quantity C set The value can be determined experimentally based on engineering parameters. Taking the 200kV multi-terminal flexible DC system as an example in the following embodiment, C is taken as... set =0.016. When a traveling wavefront is detected, if:

[0091]

[0092] If the polarity of the traveling wave front is negative, it is considered negative; otherwise, it is considered positive. If a traveling wave front is detected simultaneously at time t and time t+1, and the polarities of the traveling wave fronts are inconsistent, it is considered that a traveling wave transition has occurred, which is suspected to be a lightning disturbance.

[0093] When P sum M When (t) < -12, a fault is considered to have occurred; otherwise, a disturbance is considered to have occurred. When the lightning current identification method based on the polarity of the multi-traveling wavefront determines the current operating condition as a suspected lightning strike, and P... sum M When (t)≥-12, the current operating condition is determined to be a lightning disturbance, and the protection is locked.

[0094] The above embodiments obtain the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line, and then obtain the criterion action quantity and cumulative value. Based on the line-mode voltage difference, the criterion action quantity and cumulative value, it is determined whether the current operating condition is a lightning disturbance. In the scenario of a multi-segment flexible DC transmission system with current limiting equipment installed at the converter station outlet, it can accurately identify lightning disturbances, thereby solving the problem that lightning disturbances may cause line protection to malfunction.

[0095] Example 1

[0096] In this embodiment, RTDS is used to conduct simulation verification of lightning disturbances inside and outside the area. Figure 2 A schematic diagram of a multi-terminal flexible DC transmission system topology is shown according to an embodiment of the present invention. Figure 2 The multi-terminal flexible DC transmission system shown is analyzed. When a 1.2 / 50µs negative standard lightning wave invades line l1, for the line protection on both sides of line l1, the lightning strike occurs within the protection zone; for the line protection on both sides of line l2, the lightning strike occurs outside the protection zone.

[0097] This embodiment mainly focuses on lines l1 and l2. The structures of other lines in the multi-terminal flexible DC system are similar to those of the two lines mentioned above. Considering that the line protection on the side closest to the busbar in this type of line is directly opposite the converter and has a low risk of maloperation, the protection of the line closest to the converter is mainly considered.

[0098] The method for identifying lightning disturbances provided in this embodiment is used to determine whether the current operating condition is a lightning disturbance. If it is a lightning disturbance, the protection is locked.

[0099] Figures 3a-3c This diagram illustrates the operation result of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the midpoint of line l1 according to an embodiment of the present invention. Figure 3a , 3b Figures 3c and 3c represent the schematic diagram of the line mode voltage waveform, the schematic diagram of the traveling wave front detection result, and the schematic diagram of the cumulative value and the cumulative value summation waveform, respectively. Figures 4a-4c This diagram illustrates the operational results of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the midpoint of line l1 according to an embodiment of the present invention. Figure 4a , 4b Figures 4c and 4c represent the schematic diagram of the line mode voltage waveform, the schematic diagram of the traveling wave front detection result, and the schematic diagram of the cumulative value and the cumulative value summation waveform, respectively. Figures 5a-5c This diagram illustrates the operational results of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the midpoint of line l2 according to an embodiment of the present invention. Figure 5a , 5b Figures 5c and 5c represent the schematic diagram of the line mode voltage waveform, the schematic diagram of the traveling wave front detection result, and the schematic diagram of the cumulative value and the cumulative value summation waveform, respectively. Figures 6a-6c This diagram illustrates the operation result of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the midpoint of line l2 according to an embodiment of the present invention. Figure 6a , 6b Figures 6 and 6c represent the schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively. Figures 7a-7c This diagram illustrates the operation result of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the head end of line l1 according to an embodiment of the present invention. Figure 7a , 7b Figures 7 and 7c represent the schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively. Figures 8a-8c This diagram illustrates the operational results of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the head end of line l1 according to an embodiment of the present invention. Figure 8a , 8b Figures 8 and 8c represent the schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively. Figures 9a-9c This diagram illustrates the operation result of a lightning strike prevention method for line l1 protection against maloperation when a lightning strike occurs at the end of line l1 according to an embodiment of the present invention. Figure 9a , 9b Figures 9 and 9c represent the schematic diagrams of the line mode voltage waveform, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively. Figures 10a-10c This diagram illustrates the operation result of a lightning strike prevention method for line l2 protection against maloperation when a lightning strike occurs at the end of line l1 according to an embodiment of the present invention. Figure 10a , 10b Figures 1 and 10c show the waveform diagrams of the line-mode voltage, the traveling wave front detection result, the cumulative value, and the cumulative value summation waveform, respectively. As can be seen from the above data graphs, the action result is as expected, successfully identifying the abnormal operating condition as a lightning disturbance, and the protection was locked out.

[0100] Figure 11 A schematic diagram of a device for identifying lightning disturbances in a multi-terminal flexible DC transmission system according to an embodiment of the present invention is shown.

[0101] like Figure 11 As shown, the device includes:

[0102] Acquisition unit 1101 is used to acquire the instantaneous voltage value of the DC line;

[0103] The first processing unit 1102 is used to obtain the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line.

[0104] The second processing unit 1103 is used to obtain the criterion action quantity and the cumulative value based on the line-mode voltage difference;

[0105] The determination unit 1104 is used to determine whether the current operating condition is a lightning disturbance based on the line-mode voltage difference, the criterion action quantity, and the cumulative value.

[0106] Furthermore, the first processing unit 1102 is also used for:

[0107] The line-mode voltage of the DC line is obtained based on the instantaneous voltage value of the DC line.

[0108] The line-mode voltage difference of the DC line is obtained by calculating the difference between the line-mode voltages.

[0109] Furthermore, the DC line includes a positive line and a negative line. Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained, including:

[0110] The line-mode voltage of the DC line is obtained by subtracting the instantaneous voltage values ​​of the positive and negative lines and then dividing by 2.

[0111] Furthermore, the criterion action quantity is obtained in the following way:

[0112] The line-mode voltage difference is normalized to obtain the normalized value;

[0113] The difference between the normalized values ​​is obtained by taking the difference between the normalized values.

[0114] Multiply the normalized numerical difference with the line-mode voltage difference to obtain the criterion action quantity.

[0115] Furthermore, the cumulative sum is obtained as follows:

[0116] The cumulative value P is defined by the following formula. M (t), define P separately M (t0-1)=0:

[0117]

[0118] Where t is the time of adoption, and t0 is the initial time of adoption. Line-mode voltage differential;

[0119] Summing the cumulative values, we get the following cumulative sum:

[0120]

[0121] Furthermore, the determination unit 1104 is also used for:

[0122] If the criterion action amount is greater than the preset braking amount, it is determined that a traveling wave front has been detected.

[0123] If a traveling wave front is detected, the polarity of the traveling wave front is determined based on the line-mode voltage difference.

[0124] If a traveling wave front is detected simultaneously at the current moment and at the next moment, and the polarities of the traveling wave fronts are inconsistent, then the current working condition is determined to be a suspected lightning strike.

[0125] If the current operating condition is suspected to be a lightning strike, and the cumulative value is not less than the preset threshold, the current operating condition is determined to be a lightning strike disturbance.

[0126] Furthermore, based on the line-mode voltage difference, the polarity of the traveling wave front is determined, including:

[0127] If the line-mode voltage difference is greater than or equal to 0, the polarity of the traveling wave front is considered to be negative; otherwise, it is considered to be positive.

[0128] The above embodiments obtain the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line, and then obtain the criterion action quantity and cumulative value. Based on the line-mode voltage difference, the criterion action quantity and cumulative value, it is determined whether the current operating condition is a lightning disturbance. In the scenario of a multi-segment flexible DC transmission system with current limiting equipment installed at the converter station outlet, it can accurately identify lightning disturbances, thereby solving the problem that lightning disturbances may cause line protection to malfunction.

[0129] It should be noted that the apparatus provided in the above embodiments is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the apparatus and method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the method embodiments, which will not be repeated here.

[0130] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method for identifying lightning disturbances in a multi-terminal flexible DC transmission system provided in the above embodiments.

[0131] This invention also provides an electronic device, including: a processor; a memory for storing processor-executable instructions; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method for identifying lightning disturbances in a multi-terminal flexible DC transmission system provided in the above embodiments.

[0132] The invention has been described with reference to a few embodiments. However, as will be known to those skilled in the art, and as defined in the appended claims, other embodiments besides those disclosed above fall equivalently within the scope of the invention.

[0133] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed unless explicitly stated otherwise.

[0134] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0135] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0136] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0137] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for identifying lightning disturbances in a multi-terminal flexible DC transmission system, characterized in that, The method includes: Obtain the instantaneous voltage value of the DC line; Based on the instantaneous voltage value of the DC line, the line-mode voltage difference of the DC line is obtained; Based on the line-mode voltage difference, the criterion action quantity and the cumulative value are obtained; Based on the line-mode voltage difference, the criterion action quantity, and the cumulative value, it is determined whether the current operating condition is a lightning disturbance.

2. The method according to claim 1, characterized in that, Based on the instantaneous voltage value of the DC line, the line-mode voltage differential of the DC line is obtained, including: Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained; The line-mode voltage difference of the DC line is obtained by calculating the difference between the line-mode voltages.

3. The method according to claim 2, characterized in that, The DC line includes a positive line and a negative line. Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained, including: The line-mode voltage of the DC line is obtained by subtracting the instantaneous voltage values ​​of the positive and negative lines and then dividing by 2.

4. The method according to claim 1, characterized in that, The criterion action quantity is obtained in the following way: The line-mode voltage difference is normalized to obtain a normalized value; The difference between the normalized values ​​is obtained by taking the difference between the normalized values. Multiply the normalized numerical difference by the line-mode voltage difference to obtain the criterion action quantity.

5. The method according to claim 1, characterized in that, The cumulative value is obtained in the following manner: The cumulative value P is defined by the following formula. M (t), define P separately M (t0-1)=0: Where t is the time of adoption, and t0 is the initial time of adoption. Line-mode voltage differential; Summing the cumulative values, we get the following cumulative sum:

6. The method according to claim 1, characterized in that, Based on the line-mode voltage difference, the criterion action quantity, and the cumulative value sum, determining whether the current operating condition is a lightning disturbance includes: If the criterion action amount is greater than the preset braking amount, it is determined that a traveling wave front has been detected. If a traveling wave front is detected, the polarity of the traveling wave front is determined based on the line-mode voltage difference. If a traveling wave front is detected simultaneously at the current moment and at the next moment, and the polarities of the traveling wave fronts are inconsistent, then the current working condition is determined to be a suspected lightning strike. If the current operating condition is suspected to be a lightning strike, and the cumulative value is not less than a preset threshold, the current operating condition is determined to be a lightning strike disturbance.

7. The method according to claim 6, characterized in that, Based on the line-mode voltage difference, the polarity of the traveling wave front is determined, including: If the line-mode voltage difference is greater than or equal to 0, the polarity of the traveling wave front is considered to be negative; otherwise, it is considered to be positive.

8. A device for identifying lightning disturbances in a multi-terminal flexible DC transmission system, characterized in that, The device includes: Acquisition unit, used to acquire the instantaneous voltage value of a DC line; The first processing unit is used to obtain the line-mode voltage difference of the DC line based on the instantaneous voltage value of the DC line. The second processing unit is used to obtain the criterion action quantity and the cumulative value based on the line-mode voltage difference; The determination unit is used to determine whether the current operating condition is a lightning disturbance based on the line-mode voltage difference, the criterion action quantity, and the cumulative value sum.

9. The apparatus according to claim 8, characterized in that, The first processing unit is further configured to: Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained; The line-mode voltage difference of the DC line is obtained by calculating the difference between the line-mode voltages.

10. The apparatus according to claim 9, characterized in that, The DC line includes a positive line and a negative line. Based on the instantaneous voltage value of the DC line, the line-mode voltage of the DC line is obtained, including: The line-mode voltage of the DC line is obtained by subtracting the instantaneous voltage values ​​of the positive and negative lines and then dividing by 2.

11. The apparatus according to claim 8, characterized in that, The criterion action quantity is obtained in the following way: The line-mode voltage difference is normalized to obtain a normalized value; The difference between the normalized values ​​is obtained by taking the difference between the normalized values. Multiply the normalized numerical difference by the line-mode voltage difference to obtain the criterion action quantity.

12. The apparatus according to claim 8, characterized in that, The cumulative value is obtained in the following manner: The cumulative value P is defined by the following formula. M (t), define P separately M (t0-1)=0: Where t is the time of adoption, and t0 is the initial time of adoption. Line-mode voltage differential; Summing the cumulative values, we get the following cumulative sum:

13. The apparatus according to claim 8, characterized in that, The determination unit is further configured to: If the criterion action amount is greater than the preset braking amount, it is determined that a traveling wave front has been detected. If a traveling wave front is detected, the polarity of the traveling wave front is determined based on the line-mode voltage difference. If a traveling wave front is detected simultaneously at the current moment and at the next moment, and the polarities of the traveling wave fronts are inconsistent, then the current working condition is determined to be a suspected lightning strike. If the current operating condition is suspected to be a lightning strike, and the cumulative value is not less than a preset threshold, the current operating condition is determined to be a lightning strike disturbance.

14. The apparatus according to claim 13, characterized in that, Based on the line-mode voltage difference, the polarity of the traveling wave front is determined, including: If the line-mode voltage difference is greater than or equal to 0, the polarity of the traveling wave front is considered to be negative; otherwise, it is considered to be positive.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method described in any one of claims 1-7.

16. An electronic device comprising: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1-7.

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