Fault detection protection method, system and device based on high-voltage direct-current power transmission system

Abstract

The invention relates to the technical field of power system detection and protection, and discloses a fault detection and protection method, system and device based on a high-voltage direct-current power transmission system. The method comprises the following steps: according to a sampling frequency # imgabs0 #, respectively collecting the current at the head end and the tail end of the DC filter to obtain a head end current sequence and a tail end current sequence; multiplying the head end current and the tail end current collected at the same moment to obtain a judgment sequence; according to the time window length T, determining that the total data number of the judgment sequence in the time window length T is NT and the total point number smaller than 0 is N1, and determining that the percentage of the total point number N1 in the total data number NT is K; and determining the fault type according to the percentage K and the setting value Kset. According to the method, the fault of the power transmission line can be monitored in real time, when the fault occurs, the current synchronization at the head end and the tail end of the direct current filter changes, the fault type can be quickly judged, and the efficiency and the accuracy of judging the fault type are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system detection and protection, and in particular to a method, system and device for fault detection and protection based on a high voltage direct current transmission system. Background Art

[0002] The HVDC transmission system has the advantages of large transmission capacity, long transmission distance, and low loss, providing an effective solution for realizing large-capacity and cross-regional transmission of energy. In the new power system, HVDC transmission is becoming increasingly important. In the process of converting AC to DC, a rich set of characteristic harmonics (600Hz, 1200Hz, etc.) are generated based on the grid-commutated converter (LCC) and injected into the HVDC transmission line on the DC side. If no corresponding control measures are taken, the characteristic harmonics will cause serious harm to the power system: communication interference, reduced power quality, DC line protection malfunction, etc. As one of the important components of the HVDC transmission system, the DC filter can effectively filter out the characteristic harmonics generated by the current-commutated converter, and "escort" the safe and stable operation of the new power system.

[0003] When a ground fault occurs in a DC filter, at the very least, it will affect the filtering effect of the DC filter and cause communication interference. At worst, it will cause overvoltage or overcurrent and damage related power equipment, and even cause the high-voltage DC transmission system to shut down, causing huge energy and economic losses.

[0004] In current practical applications, the main protection of DC filters uses current differential protection to identify ground faults in DC filters. Practical operating experience shows that when a high-voltage capacitor has a high-resistance ground fault, the differential protection has problems such as insufficient reliability and poor sensitivity. It is even affected by the inconsistent transient characteristics of the current transformer, and the current differential protection has malfunctioned.

[0005] Among other commonly used solutions, some have insufficient sensitivity; or some have limitations, such as only being applicable to the ground fault of the high-end capacitor of the DC filter, and being unable to reflect the ground fault of the part below the high-end capacitor of the DC filter, and the protection setting is complex; some solutions even propose to reflect the ground fault of the DC filter in the form of harmonic impedance, but do not consider the impact of the measurement error of the transformer and the calculation error of the harmonic impedance on the protection in the engineering, and need to accurately extract the characteristic harmonics, which has high requirements on the hardware of the protection device. With the continuous improvement of the transmission capacity of new energy and the diversification of energy grid access scenarios, the operating reliability and safety of new power systems are facing new challenges. High-performance high-voltage DC filter ground fault protection is becoming increasingly important to ensure the safe and stable operation of the power system. Summary of the invention

[0006] The present invention provides a fault detection and protection method, system and device based on a high-voltage direct current transmission system, aiming to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a fault detection and protection method, system and device based on a high-voltage direct current transmission system, which can effectively improve the efficiency, accuracy and reliability of judging the type of grounding fault of a DC filter.

[0007] In a first aspect, the present invention provides a fault detection and protection method based on a high-voltage direct current transmission system, which is applied to a high-voltage direct current transmission line equipped with a direct current filter, and comprises the following steps:

[0008] According to the sampling frequency f T , respectively collecting the current at the head end and the tail end of the DC filter to obtain a head end current sequence and a tail end current sequence;

[0009] According to the head-end current sequence and the tail-end current sequence, the head-end current and the tail-end current collected at the same time are multiplied to obtain a determination sequence;

[0010] According to the time window length T, the total number of data in the judgment sequence within the time window length T is determined to be N T The total number of points with values ​​less than 0 is N1, and the total number of points N1 accounts for the total number of data N T The percentage is K;

[0011] According to the percentage K and the set value K set to determine the type of fault.

[0012] According to some embodiments of the present invention, the method further includes the following steps: when it is determined that the fault type is a DC filter grounding fault, executing a protection action.

[0013] According to some embodiments of the present invention, the percentage K and the set value K set The step of determining the size of the fault type includes the following steps:

[0014] Get the set value K set ;

[0015] Determine the percentage K and the set value K set When the percentage K is greater than the set value K set , it is determined to be a DC filter ground fault; when the percentage K is less than or equal to the setting value K sett , it is determined to be a non-DC filter area fault.

[0016] According to some embodiments of the present invention, the percentage K is:

[0017]

[0018] According to some embodiments of the present invention, the setting value K set for:

[0019]

[0020] According to some embodiments of the present invention, the sampling frequency f T It is 2000~20000Hz, and the time window length T is 0.003~0.020s.

[0021] According to some embodiments of the present invention, the first-end current sequence is: i H ={i H (0),i H (1),i H (2),…,i H (j),…,i H (N)}; the tail current sequence is: i L ={i L (0),i L (1),i L (2),…,i L (j),…,i L (N)}; j is an integer, j∈[0,N], and N is the total number of sampling points.

[0022] According to some embodiments of the present invention, the discriminant sequence is: i(k)={i L (0)*i H (0),i L (1)*i H (1),…,i L (j)*i H (j),…,i L (N)*i H (N)}; k is an integer, k∈[0,N], and N is the total number of sampling points.

[0023] In a second aspect, the present invention provides a fault detection and protection system based on a high-voltage direct current transmission system, which is applied to a high-voltage direct current transmission line equipped with a direct current filter, comprising:

[0024] The parameter acquisition module is used to obtain the sampling frequency f T , respectively collecting the current at the head end and the tail end of the DC filter to obtain a head end current sequence and a tail end current sequence;

[0025] A first calculation module, configured to multiply the head-end current and the tail-end current collected at the same time according to the head-end current sequence and the tail-end current sequence, so as to obtain a determination sequence;

[0026] The second calculation module is used to determine the total number of data in the time window length T of the judgment sequence as N according to the time window length T. T The total number of points with values ​​less than 0 is N1, and the total number of points N1 accounts for the total number of data N T The percentage is K;

[0027] The third calculation module is used to calculate the value of K according to the percentage K and the set value K set to determine the type of fault.

[0028] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the processor implements the above-mentioned fault detection and protection method based on a high-voltage direct current transmission system when executing a computer program stored in the memory.

[0029] The beneficial effects of the present invention are as follows: by collecting the current at both ends of the DC filter, the fault of the transmission line can be monitored in real time. When a fault occurs, the current synchronization at both ends of the DC filter will change. By judging that the total number of points in the sequence whose value is less than 0 within the time window length T is N1 and the total number of data is N T The percentage of the fault type can be quickly determined, which effectively improves the efficiency and accuracy of determining the fault type. In addition, the method of the present invention not only has a low sampling frequency, but also the adopted protection device hardware is easy to implement. Compared with the existing ground fault detection method, it not only simplifies the structure, but also effectively reduces the amount of protection calculations, and shortens the fault type determination time, and has the characteristics of high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of the steps of the fault detection and protection method based on the high voltage direct current transmission system of the present invention;

[0031] Figure 2 It is another step flow chart of the fault detection and protection method based on the high voltage direct current transmission system of the present invention;

[0032] Figure 3 A schematic diagram of the structure of a three-tuned DC filter in a bipolar high voltage DC transmission system used in the present invention;

[0033] Figure 4 The current trajectory distribution diagram of the DC filter used in the present invention at both ends during normal operation;

[0034] Figure 5 It is a distribution diagram of current trajectories at both ends when a ground fault f1 occurs in the high-voltage capacitor C1 region of the DC filter used in the present invention;

[0035] Figure 6It is a distribution diagram of current trajectories at both ends when a ground fault f2 occurs between the high-voltage capacitor C1 and the inductor L1 of the DC filter used in the present invention;

[0036] Figure 7 It is a distribution diagram of current trajectories at both ends when a ground fault f3 occurs between the capacitor C2 and the inductor L3 of the DC filter used in the present invention;

[0037] Figure 8 It is a structural schematic diagram of a ground fault detection and protection system of the present invention;

[0038] Fig. 9 The figure is a schematic diagram of the structure of a computer device of the present invention.

[0039] Reference numerals: DC filter 110 , high voltage DC transmission line 120 , parameter acquisition module 210 , first calculation module 220 , second calculation module 230 , memory 320 , processor 310 . DETAILED DESCRIPTION

[0040] The concept, specific structure and technical effects of the present invention will be clearly and completely described below in combination with the embodiments and drawings to fully understand the purpose, scheme and effect of the present invention.

[0041] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to another feature, or it can be indirectly fixed or connected to another feature. It should be noted that, unless otherwise specified, when a feature is referred to as being "electrically connected" or "electrically connected" to another feature, the two features can be directly connected through pins, or connected through cables, or connected by wireless transmission. The specific electrical connection method belongs to the general method of those skilled in the art, and those skilled in the art can realize the connection as needed. The singular forms of "a", "" and "the" used herein are also intended to include the majority forms, unless the context clearly indicates other meanings. In addition, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. The terms used in this specification are only for describing specific embodiments, not for limiting the present invention. The term "and / or" used herein includes any combination of one or more related listed items.

[0042] It should be understood that, although the term first, second, third etc. may be adopted to describe various elements in the present disclosure, these elements should not be limited to these terms. These terms are only used to distinguish the same type of elements from each other. For example, without departing from the scope of the present disclosure, the first element may also be referred to as the second element, and similarly, the second element may also be referred to as the first element. The use of any and all examples or exemplary language ("for example", "such as" etc.) provided herein is only intended to better illustrate embodiments of the present invention, and unless otherwise required, the scope of the present invention will not be limited.

[0043] Reference Figure 1 In a first aspect, the present invention provides a fault detection and protection method based on a high-voltage direct current transmission system, which is applied to a high-voltage direct current transmission line 120 equipped with a direct current filter 110, and comprises the following steps:

[0044] Step S100: According to the sampling frequency f T , respectively collecting the currents at the head end and the tail end of the DC filter 110 to obtain a head end current sequence and a tail end current sequence;

[0045] In the high-voltage direct current transmission system, the head end and the tail end of the direct current filter 110 are respectively equipped with current collection devices, such as current transformers. By using the corresponding current transformers, according to the set sampling frequency, the currents at the head and tail ends of the direct current filter 110 can be collected in real time, and then the head end current sequence i can be obtained. H ={i H (0),i H (1),i H (2),…,i H (j),…,i H (N)} and the tail current sequence i L ={i L (0),i L (1),i L (2),…,i L (j),…,i L (N)}, where j is an integer, j∈[0,N], and N is the total number of sampling points;

[0046] Step S200, according to the head-end current sequence and the tail-end current sequence, multiplying the head-end current and the tail-end current collected at the same time to obtain a determination sequence;

[0047] The system collects the first-end current sequence i H ={i H (0),i H (1),i H (2),…,i H (j),…,i H(N)} and the tail current sequence i L ={i L (0),i L (1),i L (2),…,i L (j),…,i L (N)}, multiply the head-end current and tail-end current collected at the corresponding moment to obtain the judgment sequence i(k)={i L (0)*i H (0),i L (1)*i H (1),…,i L (j)*i H (j),…,i L (N)*i H (N)};

[0048] Step S300: According to the time window length T, determine that the total number of data in the judgment sequence within the time window length T is N T The total number of points with values ​​less than 0 is N1, and the total number of points N1 accounts for the total number of data N T The percentage is K; according to the time window length T obtained by the system, the judgment sequence i(k)={i L (0)*i H (0),i L (1)*i H (1),…,i L (j)*i H (j),…,i L (N)*i H (N)} How many total data N will there be in the corresponding time T At the same time, the total number of points N1 of the judgment sequence i(k) less than 0 is determined in the corresponding time window length T. After the determination, the specific value of the percentage K can be determined; according to step S300, the percentage K can be obtained as:

[0049]

[0050] Then within the corresponding time window length T, the judgment sequence i(k)={i L (0)*i H (0),i L (1)*i H (1),…,i L (j)*i H (j),…,i L (N)*i H (N)} How many total data N will there be T And the total number of points N1 less than 0, and then the specific value of the percentage K can be determined;

[0051] Step S400: According to the percentage K and the set value K set to determine the type of fault.

[0052] By comparing the percentage K in the corresponding time window length T with the set value K set By looking at the size of , we can know whether a fault occurs within the corresponding time window length T, and we can determine the type of fault that occurs. After determining the type of fault, the system can decide whether to perform a protection action.

[0053] In addition, it should be noted that step S100, step S200, step S300 and step S400 of the present invention may be repeatedly executed in real time, so as to monitor the high voltage direct current transmission system in real time. When the corresponding fault type in step S400 is met, the protection action is executed to ensure the stability of the system. Similarly, when executing step S200, a step may be added:

[0054] Step S210: multiply the head-end current and the tail-end current collected at the same time, and if the result is less than 0, continue to execute steps S300 and S400; otherwise, directly continue to execute step S200.

[0055] In this way, the efficiency of system monitoring can be further improved, and the load on the system can be further reduced, thereby further improving reliability.

[0056] Reference Figure 2 In some embodiments of the present invention, the following steps are also included:

[0057] Step S500: When it is determined that the fault type is a DC filter grounding fault, a protection action is executed.

[0058] Similarly, it can be known that step S100, step S200, step S300, step S400 and step S500 of the present invention can be repeatedly executed in real time, so as to monitor the high voltage direct current transmission system in real time. When the corresponding fault type in step S400 is met, step S500 is executed, that is, the protection action is executed to ensure the stability of the system. Similarly, when executing step S200, a step can be added:

[0059] Step S210: multiply the head-end current and the tail-end current collected at the same time, and if the result is less than 0, continue to execute steps S300 and S400; otherwise, directly continue to execute step S200.

[0060] In this way, the efficiency of system monitoring can be further improved, and the load on the system can be further reduced, thereby further improving reliability.

[0061] In some embodiments of the present invention, step S400 includes the following steps:

[0062] Step S410: Obtaining the set value K set ;

[0063] Step S420: Determine the percentage K and the set value K set When the percentage K is greater than the set value K set , it is determined to be a DC filter ground fault; when the percentage K is less than or equal to the setting value K sett , it is determined to be a non-DC filter area fault.

[0064] In some embodiments of the present invention, the setting value K set for:

[0065]

[0066] According to the real-time set sampling frequency f s And the time window length T to the setting value K set By making real-time adjustments, the adaptability range of the present invention can be improved, and it can adapt to transmission lines in different situations. At the same time, the accuracy of judging the type of transmission line fault can be improved to improve reliability. In addition, it can be known that the designer can directly input a fixed value in advance as the setting value K according to the actual situation of the transmission line and combined with experience. set When executing the above step S400, the present invention can directly make a judgment based on the set value.

[0067] In some embodiments of the present invention, the sampling frequency f T It is 2000~20000Hz, and the time window length T is 0.003~0.020s.

[0068] In some embodiments of the present invention, the first-end current sequence is: i H ={i H (0),i H (1),i H (2),…,i H (j),…,i H (N)}; the tail current sequence is: i L ={i L (0),i L (1),i L (2),…,i L (j),…,i L (N)}; j is an integer, j∈[0,N], and N is the total number of sampling points.

[0069] In some embodiments of the present invention, the discriminant sequence is:

[0070] i(k)={i L (0)*i H (0),i L (1)*i H (1),…,i L (j)*i H (j),…,i L (N)*i H (N)}; k is an integer,

[0071] k∈[0,N], N is the total number of sampling points.

[0072] The beneficial effects of the present invention are as follows: by collecting the current at both ends of the DC filter 110, the fault of the transmission line can be monitored in real time. When a fault occurs, the current synchronization at both ends of the DC filter 110 will change. By judging that the total number of points in the sequence whose value is less than 0 within the time window length T is N1 and the total number of data is N T The percentage of the fault type can be quickly determined, which effectively improves the efficiency and accuracy of determining the fault type. In addition, the method of the present invention not only has a low sampling frequency, but also the adopted protection device hardware is easy to implement. Compared with the existing ground fault detection method, it not only simplifies the structure, but also effectively reduces the amount of protection calculations, and shortens the fault type determination time, and has the characteristics of high reliability.

[0073] The theoretical basis of the fault criterion proposed by the present invention is as follows:

[0074] Reference Figure 3 , which is a schematic diagram of the structure of the three-tuned DC filter 110 applied to a bipolar high-voltage DC transmission system of the present invention, wherein the rated voltage of the high-voltage DC transmission system is ±800kV and the rated current is 4kA; the smoothing reactor L p 、AC filter Z F ; 2 / 12 / 39 Triple tuned DC filter 110 parameters: C1 = 1.05μF, L1 = 9.847mH, C2 = 3.286μF, L2 = 82.95mH, R1 = 3095Ω, C3 = 5.105μF, L3 = 11.745mH; T C1 、T C2 The current transformers at the head and tail ends of the DC filter 110; i H 、i L They are current transformer T C1 、T C2The measured currents at the head and tail ends of the DC filter 110 , f1 , f2 and f3 are ground fault points set on the DC filter 110 , and f4 is a ground fault point set on the high-voltage DC transmission line 120 .

[0075] For the sake of convenience, the tail current i L The sampling point is used as the x coordinate, and the first-end current i H The sampling point is taken as the y coordinate, and the current trajectory i[x(j), y(j)] = i[i L (j),i H (j)];

[0076] When the DC filter 110 is operating normally, according to Kirchhoff's current law, the head-end current i H With the tail current i L There is the following relationship: i H =i L Therefore, when the DC filter 110 operates normally, the current trajectory i[x(j), y(j)] = i[i L (j),i H (j)] is a straight line passing through the origin, such as Figure 4 As shown, the current trajectory points i[x(j), y(j)] are concentrated in the first and third quadrants, and there are no trajectory points in the second and fourth quadrants.

[0077] When a ground fault occurs in the DC filter 110, the fault current flows into the ground through the grounding point. According to Kirchhoff's current law, the head-end current i H With the tail current i L The current trace distribution at both ends of the DC filter 110 under different fault types is as follows: Figures 5 to 7 As shown, the current trajectory point i[x(j), y(j)] is distributed in the first, second, third and fourth quadrants.

[0078] Therefore, when the DC filter 110 is operating normally and when a ground fault occurs, there is a significant difference in the distribution pattern of the current trajectory points in the second and fourth quadrants. The above characteristics can be used to construct a fault detection and protection method based on a high-voltage DC transmission system applied to the DC filter 110.

[0079] Specifically, for ease of explanation, in the embodiment of the present invention, a DC filter grounding fault is referred to as an intra-zone fault, and a non-DC filter area fault is referred to as an extra-zone fault.

[0080] Embodiment 1: Specifically, Figure 3 As a structural diagram of a specific embodiment, in this example, the current sampling frequency f T=10000Hz, time window length T = 5ms, then the setting value K can be calculated by formula (2): set =5%; and the fault type is assumed to be different types of grounding of the high-voltage capacitor C1 of the DC filter 110.

[0081] Table 1 Simulation results of different types of ground faults of the high voltage capacitor C1 of the DC filter 110

[0082]

[0083] Table 1 shows the simulation results obtained by executing steps S100, S200, S300, S400 and S500 in the present invention when different types of ground faults occur in the high-voltage capacitor C1 of the DC filter 110. In Table 1, α is the distance between the fault point and the current transformer T when a ground fault occurs in the upper bridge arm of the high-voltage capacitor C1. C1 β is the percentage of the capacitance between the fault point and the top of the lower bridge arm to the total capacitance of the bridge arm when a ground fault occurs in the lower bridge arm of the high-voltage capacitor C1.

[0084] It can be seen from Table 1 that when the high-voltage capacitor C1 of the DC filter 110 has a ground fault, the corresponding percentage K is greater than 50% and is much greater than the set value K. set (5%), which meets the ground fault protection criterion and determines that the fault type is an internal fault, that is, a DC filter ground fault. The protection has the advantages of high reliability and is not affected by transition resistance.

[0085] Embodiment 2: Specifically, Figure 3 As a structural diagram of a specific embodiment, in this example, the current sampling frequency f T =2000Hz, time window length T = 5ms, then the setting value K can be calculated by formula (2): set =4.2%; and the fault type is assumed to be a different type of grounding of the high voltage capacitor C1 of the DC filter 110.

[0086] Table 2 Sampling frequency f T Simulation results of different types of ground faults in the high-voltage capacitor C1 of the DC filter 110 at 2000Hz

[0087]

[0088] Table 2 Sampling frequency f TWhen the frequency is 2000Hz, when different types of ground faults occur in the high-voltage capacitor C1 of the DC filter 110, the simulation results obtained by executing steps S100, S200, S300, S400 and S500 in the present invention. In Table 2, α is the distance between the fault point and the current transformer T when a ground fault occurs in the upper bridge arm of the high-voltage capacitor C1. C1 β is the percentage of the capacitance between the fault point and the top of the lower bridge arm to the total capacitance of the bridge arm when a ground fault occurs in the lower bridge arm of the high-voltage capacitor C1.

[0089] It can be seen from Table 2 that when the high-voltage capacitor C1 of the DC filter 110 is grounded, the percentage K is greater than 50% and is much greater than the set value K. set (4.2%), which meets the ground fault protection criterion, and the fault type is determined to be an internal fault, that is, a DC filter ground fault. Combined with Table 2, it can be seen that when the sampling frequency f T Reduced to 2000Hz, the percentage K to the sampling frequency f T The protection still has the advantages of high reliability and no influence from transition resistance. Therefore, combined with the simulation experimental data, it can be seen that the sampling frequency f T When the frequency is 2000 Hz, it can also meet the requirements of the present invention.

[0090] Embodiment 3: The fault type is grounding faults occurring at different positions of the positive pole of the high-voltage direct current transmission line 120 .

[0091] Table 3 Simulation results when ground fault f4 occurs at different locations of the positive pole of HVDC transmission line 120

[0092]

[0093] Table 3 shows simulation results obtained by executing step S100, step S200, step S300, step S400 and step S500 in the present invention when a ground fault f4 occurs at different positions of the positive pole of the high voltage direct current transmission line 120.

[0094] It can be seen from Table 3 that when a ground fault occurs at different positions of the positive pole of the high-voltage DC transmission line 120, the percentage K required is 0, which meets the ground fault protection criterion, and the fault type is determined to be an out-of-zone fault, that is, a ground fault in the non-DC filter 110 area. The protection has the advantages of high reliability and is not affected by transition resistance.

[0095] Combining the simulation results of Table 1, Table 2 and Table 3, it can be seen that the present invention can correctly distinguish between DC filter grounding faults (in-zone faults) and non-DC filter regional faults (out-of-zone faults), has high reliability, fast judgment speed, low sampling frequency, and is not affected by the fault location and the transition resistance of the fault point.

[0096] It can be known that the present invention has the characteristics of strong resistance to transition resistance, and utilizes the full characteristic current at both ends of the DC filter 110 to realize the judgment of the DC filter grounding fault, with good protection selectivity and high reliability; and the sampling frequency is low, and only the current at the two ends needs to be sampled in real time, the structure is simple and easy to implement, so the reliability is high, and compared with the existing technology, the present invention does not need to extract single or combined information such as the amplitude, frequency, phase, etc. of the full characteristic current, which effectively reduces the amount of calculation of fault detection protection and shortens the fault judgment time, thereby effectively improving the efficiency and accuracy of fault detection.

[0097] Reference Fig. 9 In a second aspect, the present invention provides a fault detection and protection system based on a high-voltage direct current transmission system, which is applied to a high-voltage direct current transmission line 120 equipped with a direct current filter 110 branch, and includes a parameter acquisition module 210, a first calculation module 220, a second calculation module 230, a third calculation module 240 and a fourth calculation module 250; the parameter acquisition module 210 is based on a sampling frequency f T , respectively collect the current at the head end and the tail end of the DC filter 110 to obtain the head end current sequence i H and the tail current sequence i L The first calculation module 220 is used to calculate the current sequence i according to the first end H and the tail current sequence i L , multiply the head-end current and tail-end current collected at the same time to obtain a determination sequence; the second calculation module 230 is used to determine the total number of data of the determination sequence i(k) within the time window length T as N according to the time window length T. T The total number of points with values ​​less than 0 is N1, and the total number of points N1 accounts for the total number of data N T The third calculation module 240 is used to calculate the percentage K and the set value K set to determine the type of fault.

[0098] It can be known that the contents of the above-mentioned embodiments of the fault detection and protection method based on the high-voltage direct current transmission system are all applicable to the embodiments of the present system, and the functions specifically implemented by the embodiments of the present system are the same as those of the above-mentioned embodiments of the fault detection and protection method based on the high-voltage direct current transmission system, and the beneficial effects achieved are also the same as those achieved by the above-mentioned embodiments of the fault detection and protection method based on the high-voltage direct current transmission system.

[0099] Reference Figure 8 In a third aspect, the present invention provides a computer device, including a memory 220 and a processor 210, wherein the processor 210 implements the above-mentioned fault detection and protection method based on the high-voltage direct current transmission system when executing a computer program stored in the memory 220.

[0100] Similarly, the contents of the above-mentioned fault detection and protection method embodiment based on the high-voltage direct current transmission system are all applicable to the embodiment of the present device. The functions specifically implemented by the embodiment of the present device are the same as those of the above-mentioned method embodiment, and the beneficial effects achieved are also the same as those achieved by the above-mentioned fault detection and protection method embodiment based on the high-voltage direct current transmission system.

[0101] Reference Fig. 9 In a third aspect, the present invention provides a computer device, including a memory 320 and a processor 310, wherein the processor 310 implements the above-mentioned ground fault detection and protection method when executing a computer program stored in the memory 320.

[0102] Similarly, the contents of the above-mentioned ground fault detection and protection method embodiment are applicable to the present device embodiment. The functions specifically implemented by the present device embodiment are the same as those of the above-mentioned method embodiment, and the beneficial effects achieved are also the same as those achieved by the above-mentioned ground fault detection and protection method embodiment.

[0103] It should be appreciated that the method steps in the embodiments of the present invention can be implemented or implemented by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer readable memory. The fault detection and protection method based on the high voltage direct current transmission system can use standard programming techniques. Each program can be implemented in a high-level process or object-oriented programming language to communicate with the computer system. However, if necessary, the program can be implemented in assembly or machine language. In any case, the language can be a compiled or interpreted language. In addition, the program can be run on a programmed dedicated integrated circuit for this purpose.

[0104] Furthermore, the operations of the processes described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The processes described herein (or variations and / or combinations thereof) may be performed under the control of one or more computer systems configured with executable instructions, and may be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) that is executed collectively on one or more processors, by hardware, or a combination thereof. A computer program includes a plurality of instructions that may be executed by one or more processors.

[0105] Further, the method can be implemented in any type of computing platform that is operably connected to a suitable computer, including but not limited to a personal computer, a minicomputer, a mainframe, a workstation, a network or distributed computing environment, a separate or integrated computer platform, or in communication with a charged particle tool or other imaging device, etc. Various aspects of the present invention can be implemented in machine-readable code stored on a non-transitory storage medium or device, whether removable or integrated into a computing platform, such as a hard disk, an optical read and / or write storage medium, a RAM, a ROM, etc., so that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the process described herein. In addition, the machine-readable code, or a portion thereof, can be transmitted via a wired or wireless network. When such media includes instructions or programs that implement the above steps in conjunction with a microprocessor or other data processor, the invention herein includes these and other different types of non-transitory computer devices. When programmed according to the methods and techniques of the present invention, the present invention can also include the computer itself.

[0106] The computer program can be applied to input data to perform the functions herein, thereby converting the input data to generate output data stored in a non-volatile memory. The output information can also be applied to one or more output devices such as a display. In a preferred embodiment of the present invention, the converted data represents physical and tangible objects, including specific visual depictions of physical and tangible objects produced on the display.

[0107] The above are only preferred embodiments of the present invention. The present invention is not limited to the above embodiments. As long as the technical effects of the present invention are achieved by the same means, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention. Within the scope of protection of the present invention, its technical solutions and / or implementation methods may have various modifications and changes.

Claims

1. A fault detection and protection method based on a high-voltage direct current transmission system, applied to a high-voltage direct current transmission line equipped with a direct current filter, characterized in that: The following steps are involved: According to the sampling frequency f T , respectively collecting the current at the head end and the tail end of the DC filter to obtain a head end current sequence and a tail end current sequence; According to the head-end current sequence and the tail-end current sequence, the head-end current and the tail-end current collected at the same time are multiplied to obtain a determination sequence; According to the time window length T, the total number of data in the judgment sequence within the time window length T is determined to be N T The total number of points with values ​​less than 0 is N1, and the total number of points N1 accounts for the total number of data N T The percentage is K; According to the percentage K and the set value K set to determine the type of fault.

2. The fault detection and protection method based on the high voltage direct current transmission system according to claim 1 is characterized in that: The following steps are also included: When it is determined that the fault type is a DC filter grounding fault, a protection action is performed.

3. The fault detection and protection method based on the high voltage direct current transmission system according to claim 1 is characterized in that: The percentage K and the set value K set The step of determining the size of the fault type includes the following steps: Get the set value K set ; Determine the percentage K and the set value K set When the percentage K is greater than the set value K set , it is determined to be a DC filter ground fault; when the percentage K is less than or equal to the setting value K sett , it is determined to be a non-DC filter area fault.

4. The fault detection and protection method based on the high voltage direct current transmission system according to any one of claims 1 to 3, characterized in that: The percentage K is:

5. The fault detection and protection method based on the high voltage direct current transmission system according to any one of claims 1 to 3, characterized in that: Setting value K set for:

6. The fault detection and protection method based on the high voltage direct current transmission system according to any one of claims 1 to 3 The method is characterized in that Sampling frequency f T It is 2000~20000Hz, and the time window length T is 0.003~0.020s.

7. The fault detection and protection method based on the high voltage direct current transmission system according to claim 1 or 2, characterized in that: The first-end current sequence is: i H ={i H (0),i H (1),i H (2),…,i H (j),…,i H (N)}; Said tail end current order: i L ={i L (0),i L (1), i L (2),…,i L (j),…,i L (N)}; j is an integer, j∈[0,N], and N is the total number of sampling points.

8. The fault detection and protection method based on the high voltage direct current transmission system according to claim 7 is characterized in that: The discriminant sequence is: i(k)={i L (0)*i H (0),i L (1)*i H (1),…,i L (j)*i H (j),…,i L (N)*i H (N)}; k is an integer, k∈[0,N], and N is the total number of sampling points.

9. A fault detection and protection system based on a high-voltage direct current transmission system, applied to a high-voltage direct current transmission line equipped with a direct current filter, characterized in that: include: The parameter acquisition module is used to obtain the sampling frequency f T , respectively collecting the current at the head end and the tail end of the DC filter to obtain a head end current sequence and a tail end current sequence; A first calculation module, configured to multiply the head-end current and the tail-end current collected at the same time according to the head-end current sequence and the tail-end current sequence, so as to obtain a determination sequence; The second calculation module is used to determine the total number of data in the time window length T of the judgment sequence as N according to the time window length T. T The total number of points with values ​​less than 0 is N1, and the total number of points N1 accounts for the total number of data N T The percentage is K; The third calculation module is used to calculate the value of K according to the percentage K and the set value K set to determine the type of fault.

10. A computer device comprising a memory and a processor, characterized in that: When the processor executes the computer program stored in the memory, the fault detection and protection method based on the high voltage direct current transmission system according to any one of claims 1 to 8 is implemented.

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