A method and device for monitoring reactor fault

Abstract

The present invention provides a method and device for monitoring reactor faults. The method collects the real-time value of branch current of each phase of each bandpass filter group in real time for each bandpass filter group; calculates the real-time value of zero-sequence current of three-phase branch of the bandpass filter group based on the real-time value of branch current; calculates the 11th or 13th first characteristic harmonic value in the real-time value of zero-sequence current of three-phase branch; compares the first characteristic harmonic value with the set value respectively, and when there is a second characteristic harmonic value greater than the set value and meeting the fault occurrence condition in the first characteristic harmonic value, it is determined that the reactor has a turn-to-turn short circuit fault. In this solution, during the operation of the power system, it is determined whether the current bandpass filter has a turn-to-turn short circuit fault according to the change of the 11th or 13th characteristic harmonic value in the real-time value of zero-sequence current of three-phase branch of each bandpass filter group in real time, so as to achieve the purpose of quickly, effectively and sensitively discovering reactor faults.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment fault monitoring and fault protection, and in particular to a reactor fault monitoring method and device. Background Art

[0002] At present, most AC filters configured in converter stations of DC transmission systems or AC / DC systems use dry-type air-core reactors, which are used to provide reactive power compensation. Typical AC filters include bandpass filter groups (such as BP11, BP13), high-pass filter groups (such as HP24 / 36), and HP3 and SC groups. Figure 1 The main wiring diagram of the 500kv bandpass (BP11, BP13) single tuned filter is shown.

[0003] In the typical ±800kV DC transmission system that is currently under construction and put into operation in large numbers, the AC field side of the conventional DC (12-pulsation thyristor rectifier) ​​converter station must be equipped with a bandpass (BP) single tuned filter (BP11 and BP13) that filters out the 11th and 13th harmonics with the largest harmonics, as well as a high pass filter (such as HP24 / 36) that filters out the 23rd and 25th harmonics, and filters out the 35th, 37th and higher harmonics. In order to meet the requirements of N+1 reliability and reactive power compensation capacity, multiple groups of bandpass single tuned filters BP11 and BP13 and four groups of high pass filters HP24 / 36 are generally configured.

[0004] During the operation of the DC transmission system, once a turn-to-turn short-circuit fault occurs in the dry-type air-core reactor in the filter group, the two-port equivalent resistance and inductance values ​​in the filter group will change with the development of the short circuit and the increase in the number of turns, causing the tuning frequency of the filter to shift significantly, thereby affecting the passband impedance characteristics of the characteristic harmonic current of a specific frequency, and further affecting the filtering effect.

[0005] Therefore, there is an urgent need for a method to quickly and sensitively detect reactor faults. Summary of the invention

[0006] In view of this, an embodiment of the present invention provides a method and device for monitoring reactor faults, so as to achieve the purpose of quickly and sensitively detecting reactor faults.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] A first aspect of an embodiment of the present invention discloses a reactor fault monitoring method, which is applicable to a power system equipped with a bandpass filter group. The method comprises:

[0009] For each group of band-pass filter groups, real-time values ​​of branch currents of each phase of the band-pass filter group are collected in real time;

[0010] Calculate the real-time value of the three-phase branch zero-sequence current of the bandpass filter group based on the real-time value of the branch current;

[0011] Calculate the mth order first characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch, where the value of m is 11 or 13;

[0012] Compare the first characteristic harmonic values ​​with set values ​​respectively, and determine that a turn-to-turn short circuit fault occurs in the reactor when a second characteristic harmonic value greater than the set value and meeting a fault occurrence condition exists among the first characteristic harmonic values;

[0013] The fault occurrence condition is (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, where n refers to the nth group of bandpass filters, and the value of n is greater than or equal to 1, ΔHRI m (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI m (f) is the maximum value among the second characteristic harmonic values ​​that are greater than the set value.

[0014] Optionally, also include:

[0015] Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition;

[0016] If the number is 1, it is determined that the bandpass filter group having the second characteristic harmonic value is a faulty group.

[0017] Optionally, also include:

[0018] Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition;

[0019] If the number is 2, determining a first band-pass filter group and a second band-pass filter group having the second characteristic harmonic value;

[0020] Respectively calculating the mth third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter;

[0021] It is determined that the corresponding band-pass filter group with the smallest third characteristic harmonic value is the fault group, and the other band-pass filter group is the non-fault group.

[0022] Optionally, also include:

[0023] Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition;

[0024] If the number is 2, determining a first band-pass filter group and a second band-pass filter group having the second characteristic harmonic value;

[0025] The second characteristic harmonic values ​​of the first band-pass filter group and the second band-pass filter group are compared to determine that the band-pass filter group with a relatively small second characteristic harmonic value is a faulty group and the other band-pass filter group is a non-faulty group.

[0026] Optionally, also include:

[0027] Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition;

[0028] If the number is greater than or equal to 3, the bandpass filter group with the largest second characteristic harmonic value is determined to be a faulty group, and the bandpass filter group with other second characteristic harmonic values ​​in a set proportion to the largest second characteristic harmonic value is a non-faulty group, and the set proportion is 0.33 to 0.5.

[0029] A second aspect of the present invention discloses a reactor fault monitoring device, which is applicable to a power system equipped with a bandpass filter group. The method comprises:

[0030] A real-time acquisition module, used for acquiring the real-time value of the branch current of each phase of each band-pass filter group in real time for each band-pass filter group;

[0031] A calculation module, used for calculating the real-time value of the three-phase branch zero-sequence current of the bandpass filter group based on the real-time value of the branch current; and calculating the mth first characteristic harmonic value in the real-time value of the three-phase branch zero-sequence current, where the value of m is 11 or 13;

[0032] A comparison module, used for comparing the first characteristic harmonic value with a set value respectively, and determining that a turn-to-turn short circuit fault occurs in the reactor when a second characteristic harmonic value greater than the set value and meeting a fault occurrence condition exists in the first characteristic harmonic value;

[0033] The fault occurrence condition is (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, where n refers to the nth group of bandpass filters, and the value of n is greater than or equal to 1, ΔHRI m (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI m (f) is the maximum value among the second characteristic harmonic values ​​that are greater than the set value.

[0034] Optionally, the device further comprises:

[0035] An acquisition module, used for acquiring the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition;

[0036] A fault locating module is configured to determine, if the number is 1, that the bandpass filter group having the second characteristic harmonic value is a faulty group.

[0037] Optionally, the device further comprises:

[0038] An acquisition module, used to acquire the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; if the number is 2, determining a first bandpass filter group and a second bandpass filter group having the second characteristic harmonic value;

[0039] The calculation module is further used to respectively calculate the mth third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter;

[0040] The fault location module determines that the corresponding band-pass filter group with the smallest third characteristic harmonic value is the fault group, and the other band-pass filter group is the non-fault group.

[0041] Optionally, the device further comprises:

[0042] An acquisition module, used to acquire the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; if the number is 2, determining a first bandpass filter group and a second bandpass filter group having the second characteristic harmonic value;

[0043] The fault location module is used to compare the second characteristic harmonic values ​​of the first bandpass filter group and the second bandpass filter group, and determine that the bandpass filter group with a relatively small second characteristic harmonic value is a faulty group and the other bandpass filter group is a non-faulty group.

[0044] Optionally, the device further comprises:

[0045] An acquisition module, used for acquiring the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition;

[0046] A fault location module is used to determine that the bandpass filter group with the largest second characteristic harmonic value is a faulty group if the number is greater than or equal to 3, and the bandpass filter groups with other second characteristic harmonic values ​​in a set proportion to the maximum second characteristic harmonic value are non-faulty groups, and the set proportion is 0.33 to 0.5.

[0047] A reactor fault monitoring method and device are provided based on the above-mentioned embodiment of the present invention. The method is applicable to a power system equipped with a bandpass filter group. For each group of bandpass filter groups, the real-time value of the branch current of each phase of the bandpass filter group is collected in real time; the real-time value of the zero-sequence current of the three-phase branch of the bandpass filter group is calculated based on the real-time value of the branch current; the 11th or 13th first characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch is calculated; the first characteristic harmonic value is compared with a set value respectively, and when there is a second characteristic harmonic value in the first characteristic harmonic value that is greater than the set value and meets the fault occurrence condition, it is determined that the reactor has a turn-to-turn short circuit fault; wherein the fault occurrence condition is (0.33-1)ΔHRI 11 (f) = ΔHRI 11 (nf)>Idz, where n refers to the nth group of bandpass filters, and the value of n is greater than or equal to 1, ΔHRI 11 (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI 11 (f) is the maximum value of the second characteristic harmonic value greater than the set value. In this solution, during the operation of the power system, according to the change of the 11th or 13th characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch of each group of band-pass filters, it is determined whether the current band-pass filter has a turn-to-turn short circuit fault, which can achieve the purpose of quickly, effectively and sensitively discovering the reactor fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0049] Figure 1 It is the main wiring diagram of an existing bandpass (BP11, BP13) single tuned filter;

[0050] Figure 2 This is a comparison diagram of the harmonic impedance curves of the filter BP11 group before and after the inter-turn short circuit fault;

[0051] Figure 3 A schematic flow chart of a reactor fault monitoring method disclosed in an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of the structure of a reactor fault monitoring device disclosed in an embodiment of the present invention;

[0053] Figure 5This is the wiring schematic diagram of the bandpass filter BP11 and BP13 group in the 500kV AC filter of the conventional DC converter station;

[0054] Figure 6 This is a schematic diagram of inter-turn short circuit after the insulation failure of a certain turn of dry-type air-core filter coil;

[0055] Figure 7 It is a schematic diagram of the electromagnetic induction principle of short-circuit between turns of an air-core coil;

[0056] Figure 8 This is a simplified calculation diagram of harmonic impedance and harmonic current of a typical 500kV AC bandpass BP11 and BP13 filter group;

[0057] R: resistance; C: capacitance; L: inductance. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0060] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0061] As can be seen from the background technology, the filter groups in the current DC transmission system mostly use dry-type air-core reactors. Among them, the typical configuration of the AC filter and its filter reactor of the conventional ±800kV DC transmission converter station 500kV filter is shown in Table 1. The technical parameters of the filter reactor of the typical bandpass AC filter BP11 and BP13 group are shown in Table 2.

[0062] Table 1:

[0063]

[0064]

[0065] Table 2:

[0066]

[0067] According to calculation and actual measurement, once the dry-type air-core reactor in the filter group has an inter-turn short-circuit fault, the two-port equivalent resistance and inductance values ​​in the filter group will change with the development of the short circuit and the increase of the number of turns. In particular, for the single-tuned bandpass filter group in Table 1, when the inductor has an inter-turn short-circuit fault, as the equivalent inductance continues to decrease, the tuning frequency of the fault phase filter will shift significantly, such as Figure 2 As shown, the tuning frequency before and after the fault shifts from 550 Hz to 580 Hz, thereby affecting the passband impedance characteristics of the characteristic harmonic current of a specific frequency, thereby affecting the filtering effect.

[0068] Therefore, the embodiment of the present invention discloses a method and device for monitoring reactor faults, which can quickly, effectively and sensitively detect reactor faults by determining whether the current bandpass filter has a turn-to-turn short circuit fault according to the change of the 11th or 13th characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch of each group of bandpass filters during the operation of the power system. This is described in detail in the following embodiments.

[0069] like Figure 3 FIG. 1 is a flow chart of a reactor fault monitoring method disclosed in an embodiment of the present invention. The method is applicable to a power system equipped with a bandpass filter group. The method mainly comprises the following steps:

[0070] S301: For each group of band-pass filter groups, real-time values ​​of branch currents of each phase of the band-pass filter groups are collected in real time.

[0071] S302: Calculate the real-time value of the three-phase branch zero-sequence current of the bandpass filter group based on the real-time value of the branch current.

[0072] For the current power system, especially the typical ±800kV DC transmission system, in order to meet the N+1 reliability and reactive compensation capacity requirements, multiple groups of bandpass single-tuned filters BP11 and BP13 will be configured. During the execution of S301 and S302, when the reactor fault is detected online in real time, it is necessary to calculate the real-time branch current value of each phase of each group of bandpass filters and the real-time value of the three-phase branch zero-sequence current.

[0073] In the specific execution of S302, the real-time value of the zero-sequence current of the three-phase branch of the bandpass filter group is calculated based on the real-time value of the branch current using formula (1).

[0074] ΔI gn (t) = I gn (A)(t)+I gn (B)(t)+I gn (C)(t) (1)

[0075] Among them, I gn (A / B / C)(t) is the real-time current of each phase of the nth (n=1, 2, 3, 4) BP11 filter group, ΔI gn (t) is the real-time value of zero-sequence current of the three-phase branch of the nth BP11 filter group.

[0076] S303: Calculate the mth order first characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch.

[0077] In S303, the value of m is 11 or 13. That is, S303 is executed to calculate the 11th first characteristic harmonic value or the 13th first characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch.

[0078] It should be noted that the first characteristic harmonic value, the second characteristic harmonic value, the third characteristic harmonic value, etc. disclosed in the embodiments of the present invention are all characteristic harmonic current values.

[0079] S304: Compare the first characteristic harmonic values ​​with set values ​​respectively, and when there is a second characteristic harmonic value among the first characteristic harmonic values ​​that is greater than the set value and meets the fault occurrence condition, determine that a turn-to-turn short circuit fault occurs in the reactor.

[0080] In S304, the fault occurrence condition is as shown in formula (2).

[0081] (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz (2)

[0082] Where n refers to the nth group of bandpass filters, the value of n is greater than or equal to 1, ΔHRI m (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI m (f) is the maximum value among the second characteristic harmonic values ​​that are greater than the set value, and Idz is the set value.

[0083] In a specific implementation, the value of Idz is usually set to 15%-20% of the 11th or 13th harmonic design rated current value of the filter reactance of the AC filter group BP11 or BP13.

[0084] The process of executing S304 for the 11th first characteristic harmonic value in the real-time value of the three-phase branch zero-sequence current is as follows:

[0085] First, the obtained multiple first characteristic harmonic values ​​are compared with a set value to obtain a second characteristic harmonic value greater than the set value.

[0086] Then, determine the minimum value ΔHRI among the second characteristic harmonic values 11 (nf) and maximum ΔHRI 11 (f) , use formula (1) to make a judgment.

[0087] If the minimum value of the second characteristic harmonic value ΔHRI 11 (nf) and maximum ΔHRI 11 (f) Comply with (0.33-1)ΔHRI 11 (f) = ΔHRI 11 (nf)>Idz, it is determined that the reactor has a turn-to-turn short-circuit fault.

[0088] If the minimum value of the second characteristic harmonic value ΔHRI 11 (nf) and maximum ΔHRI 11 (f) Does not meet 0.33-1)ΔHRI 11 (f) = ΔHRI 11 (nf)>Idz, it is determined that the reactor has no turn-to-turn short-circuit fault.

[0089] The process of executing S304 for the 13th first characteristic harmonic value in the real-time value of the three-phase branch zero-sequence current is as follows:

[0090] First, the obtained multiple first characteristic harmonic values ​​are compared with a set value to obtain a second characteristic harmonic value greater than the set value.

[0091] Then, determine the minimum value ΔHRI among the second characteristic harmonic values 13 (nf) and maximum ΔHRI 13 (f) , use formula (1) to make a judgment.

[0092] If the minimum value of the second characteristic harmonic value ΔHRI 13 (nf) and maximum ΔHRI 13 (f) Comply with (0.33-1)ΔHRI 13 (f) = ΔHRI 13 (nf)>Idz, it is determined that the reactor has a turn-to-turn short-circuit fault.

[0093] If the minimum value of the second characteristic harmonic value ΔHRI 13 (nf) and maximum ΔHRI13 (f) Does not meet 0.33-1)ΔHRI 13 (f) = ΔHRI 13 (nf)>Idz, it is determined that the reactor has no turn-to-turn short-circuit fault.

[0094] In the reactor fault monitoring method disclosed in the embodiment of the present invention, it is determined in real time whether the current bandpass filter has a turn-to-turn short circuit fault based on the changes in the 11th or 13th characteristic harmonic values ​​in the real-time values ​​of the three-phase branch zero-sequence current of each group of bandpass filters, thereby achieving the purpose of quickly, effectively and sensitively detecting the reactor fault.

[0095] During the specific operation of the power system, after determining that the reactor has an inter-turn short-circuit fault, for situations where only one, two, or three or more band-pass filter groups BP11 (or BP13) are operating simultaneously, different identification and judgment methods are used to locate the band-pass filter with the inter-turn short-circuit fault.

[0096] For the case of running only one group:

[0097] S401: Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition.

[0098] S402: If the number is 1, determine that the bandpass filter group having the second characteristic harmonic value is a faulty group.

[0099] When executing S402, when there is only one bandpass filter group with a second characteristic harmonic value greater than the set value and meeting the fault condition, that is, only one bandpass filter group has an increment, then the only bandpass filter group with an increment is the faulty group.

[0100] For the case of 2 groups running:

[0101] S501: If the number is 2, determine a first band-pass filter group and a second band-pass filter group that have the second characteristic harmonic value.

[0102] S502: Calculate the mth third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter respectively.

[0103] In the specific execution of S501, the 11th third characteristic harmonic value HRI in the real-time value of the branch current of each phase of the first bandpass filter group and the second bandpass filter is calculated respectively. 11 (gn)(A / B / C).

[0104] Alternatively, the 13th third characteristic harmonic value HRI in the real-time value of the branch current of each phase of the first bandpass filter group and the second bandpass filter is calculated respectively. 13 (gn)(A / B / C).

[0105] S503: Determine that the corresponding band-pass filter group with the smallest third characteristic harmonic value is a faulty group, and the other band-pass filter group is a non-faulty group.

[0106] In the specific process of executing S503, the maximum value and the minimum value are calculated using formula (3) and formula (4), and the mth order third characteristic harmonic values ​​in all phase currents of two or more groups are calculated and compared.

[0107] HRI m (nf) = max{HRI m (g1(abc)),HRI m (g2(abc)),HRI m (g3(abc)),HRI m (g4(abc))}(3)

[0108] HRI m (f) = min{HRI m (g1(abc)),HRI m (g2(abc)),HRI m (g3(abc)),HRI m (g4(abc))}(4)

[0109] The process of calculating and comparing the 11th third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter is based on:

[0110] HRI 11 (nf) = max{HRI 11 (g1(abc)),HRI 11 (g2(abc)),HRI 11 (g3(abc)),HRI 11 (g4(abc))}

[0111] HRI 11 (f) = min{HRI 11 (g1(abc)),HRI 11 (g2(abc)),HRI 11 (g3(abc)),HRI 11 (g4(abc))}

[0112] The process of calculating and comparing the 13th third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter is based on:

[0113] HRI 13 (nf) = max{HRI 13 (g1(abc)),HRI 13 (g2(abc)),HRI 13 (g3(abc)),HRI 13 (g4(abc))}

[0114] HRI 13 (f) = min{HRI 13 (g1(abc)),HRI 13 (g2(abc)),HRI 13 (g3(abc)),HRI 13 (g4(abc))}

[0115] Finally, it is determined that the corresponding band-pass filter group with the smallest third characteristic harmonic value is the faulty group, and the other band-pass filter group is the non-faulty group.

[0116] In another embodiment, for a bandpass filter group having two second characteristic harmonic values ​​greater than a set value and meeting a fault occurrence condition, a first bandpass filter group and a second bandpass filter group having the second characteristic harmonic value can also be determined, and then the second characteristic harmonic values ​​of the first bandpass filter group and the second bandpass filter group are compared to determine that the bandpass filter group with a relatively small second characteristic harmonic value is a faulty group, and the other bandpass filter group is a non-faulty group.

[0117] For more than 3 groups:

[0118] S601: If the number is greater than or equal to 3, determine that the bandpass filter group with the largest second characteristic harmonic value is a faulty group, and the bandpass filter groups with other second characteristic harmonic values ​​in a set proportional relationship to the largest second characteristic harmonic value are non-faulty groups.

[0119] In S602, the set ratio includes but is not limited to 0.33-0.5, and may also be 0.3 or 0.55.

[0120] After the embodiment of the present invention determines that a turn-to-turn short-circuit fault has occurred, considering that the maximum probability time or opportunity occurs when the DC commutation power is close to the maximum power and under a relatively large harmonic current operating condition, therefore, for the case where only one group is in operation, once a unique increment occurs, it indicates that a turn-to-turn short-circuit fault has occurred in the currently operating bandpass filter. For the case where two groups are running in parallel at the same time, the faulty group can also be quickly located by calculating the characteristic harmonic values ​​of the two groups of 6 phases. For the case where the number of groups running in parallel at the same time is between 3 and 4 groups, the comparison, identification and judgment of the zero-sequence current increment under the condition of multiple groups running at the same time can quickly locate the bandpass filter group where a turn-to-turn short-circuit fault has occurred.

[0121] Based on the reactor fault monitoring method disclosed in the above embodiment of the present invention, the embodiment of the present invention further discloses a reactor fault monitoring device, which is suitable for a power system equipped with a bandpass filter group, such as Figure 4 As shown, the reactor fault monitoring device includes: a real-time acquisition module 41, a calculation module 42 and a comparison module 43.

[0122] The real-time acquisition module 41 is used to acquire the real-time value of the branch current of each phase of each band-pass filter group in real time.

[0123] The calculation module 42 is used to calculate the real-time value of the three-phase branch zero-sequence current of the bandpass filter group based on the real-time value of the branch current; and calculate the mth first characteristic harmonic value in the real-time value of the three-phase branch zero-sequence current, where the value of m is 11 or 13.

[0124] The comparison module 43 is used to compare the first characteristic harmonic value with the set value respectively, and when there is a second characteristic harmonic value in the first characteristic harmonic value that is greater than the set value and meets the fault condition, it is determined that the inductor has a turn-to-turn short circuit fault.

[0125] The fault occurrence condition is (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, where n refers to the nth group of bandpass filters, and the value of n is greater than or equal to 1, ΔHRI m (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI m (f) is the maximum value among the second characteristic harmonic values ​​that are greater than the set value.

[0126] In one embodiment, the device further comprises:

[0127] The acquisition module is used to acquire the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting the fault occurrence condition.

[0128] A fault locating module is configured to determine, if the number is 1, that the bandpass filter group having the second characteristic harmonic value is a faulty group.

[0129] In one embodiment, the device further comprises:

[0130] An acquisition module is used to obtain the number of bandpass filter groups that have a second characteristic harmonic value greater than a set value and that meets the fault occurrence condition; if the number is 2, determine the first bandpass filter group and the second bandpass filter group that have the second characteristic harmonic value.

[0131] The calculation module is also used to respectively calculate the mth third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter.

[0132] The fault location module determines that the corresponding band-pass filter group with the smallest third characteristic harmonic value is the fault group, and the other band-pass filter group is the non-fault group.

[0133] In one embodiment, the device further comprises:

[0134] An acquisition module is used to obtain the number of bandpass filter groups that have a second characteristic harmonic value greater than a set value and that meets the fault occurrence condition; if the number is 2, determine the first bandpass filter group and the second bandpass filter group that have the second characteristic harmonic value.

[0135] The fault location module is used to compare the second characteristic harmonic values ​​of the first bandpass filter group and the second bandpass filter group, and determine that the bandpass filter group with a relatively small second characteristic harmonic value is a faulty group and the other bandpass filter group is a non-faulty group.

[0136] In one embodiment, the device further comprises:

[0137] The acquisition module is used to acquire the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting the fault occurrence condition.

[0138] A fault location module is used to determine that the bandpass filter group with the largest second characteristic harmonic value is a faulty group if the number is greater than or equal to 3, and the bandpass filter groups with other second characteristic harmonic values ​​in a set proportion to the maximum second characteristic harmonic value are non-faulty groups, and the set proportion is 0.33 to 0.5.

[0139] To further illustrate the implementation principle of a reactor fault monitoring method and device disclosed in the above embodiment of the present invention, Figure 5The wiring schematic diagram of the bandpass filters BP11 and BP13 group in the conventional DC converter station 500kV AC filter is shown, and the typical configuration parameters of the bandpass filters BP11 and BP13 group in the conventional DC converter station 500kV AC filter are shown in Table 3 for explanation.

[0140] Table 3:

[0141]

[0142] like Figure 6 As shown in the figure, when a filter reactor in the bandpass filter BP11 and BP13 group has an inter-turn short circuit fault, that is, the insulation between adjacent turns of a phase coil (mainly thin film) is reduced due to aging or damaged due to overheating or overvoltage. As a result, breakdown discharge and short circuit between failed membranes occur, arcs burn at the short circuit, and short-circuit loop current flows between short-circuited turns (Ic2). The current in the short-circuit loop is dozens to dozens of times the coil current (Ic), and the current direction is opposite to the coil current.

[0143] When a part of the turns in the hollow coil is short-circuited between adjacent turns, the short-circuited turns and the normal turns are connected by an AC electromagnetic field. The electromagnetic induction principle between the short-circuited turns and the normal turns on a certain small scale in the adjacent space is the same as the induction relationship between the primary and secondary independent coils with good magnetic field coupling. Figure 7 As shown, the whole coil is divided into three series parts, namely L11, L12 and L13, and the corresponding inductances are k11*L, k12*L, k13*L.

[0144] The corresponding number of turns is N11, N12, and N13, among which several turns in coil L12 have inter-turn short circuits, and the number of short-circuited turns is N2, which is equivalent to the secondary coil L2 of coil L12, and the coils L2 and L12 have a complete flux coupling relationship like an ideal transformer.

[0145] The short-circuit turn and the normal turn with magnetic flux tightly hinged within a certain space size range form a magnetic flux ampere-turn balance relationship based on the principle of electromagnetic induction. Actual measurement and theoretical calculation show that the short-circuit circulating current ampere-turn balance magnetic flux caused by a short-circuit turn is about 1-3% of the total ampere-turn of the entire coil. Figure 7 The principle is illustrated, and the relationship shown in formula (5) can be obtained.

[0146] N12*I1(t)+N2*I2(t)=0 (5)

[0147] Among them, N12 is a normal turn with a certain number of turns, that is, the primary turns, and I1(t) is the real-time current passing through the coil, that is, the primary current.

[0148] N2 is the number of short-circuit turns, i.e., the secondary turns, and I2(t) is the real-time current of the short-circuit loop, i.e., the secondary current.

[0149] When the arc burns, the local coil inductance disappears after the real-time ampere-turn balance, that is, L12=0.

[0150] After the local short-circuit turns are balanced with the surrounding normal turns, the coil inductance here will disappear and be lost. However, the short-circuit current of the short-circuit ring increases to dozens of times of the original value, consuming a large amount of active power and energy. The equivalent circuit parameters are equalized from the two ports of the primary side, and the equivalent resistance is shown in formula (6):

[0151]

[0152] Among them, Rs is the single turn resistance.

[0153] According to actual measurements and theoretical calculations, according to the different inductance values ​​of the filter reactor, when the short-circuit turns are in the scale of 1 to 30 turns, the short-circuit ring current is about 30 to 200 times the coil current, that is, I2 / I1 = (30 to 200) times. The inductance values ​​of the filter BP11 and BP13 groups in Table 3 are very large. Since the inter-turn short-circuit currents of the filter reactors with different inductance values ​​and different total turns are very different after the inter-turn short-circuit occurs, the development speed is also very different. Obviously, the development speed of the filter BP11 and BP13 groups after the inter-turn short-circuit fault occurs is much greater than that of the reactor in the high-pass HP 24 / 36 group configured in the converter station. In addition, the larger the inductance value, according to statistics and experience, the greater the probability of the reactor inter-turn short-circuit.

[0154] According to formula (5), as the number of short-circuit turns increases, more surrounding normal turns are required to participate in the electromagnetic induction ampere-turn balance, so the inductance loss increases until it approaches 0; at the same time, according to formula (6), as the number of short-circuit turns increases, the equivalent resistance also increases. Experience shows that the equivalent resistance is about 1 / 3 to 1 / 2 of the loss of power frequency reactance.

[0155] Assumptions Figure 5 The B-phase filter reactor of one of the middle filters BP11 and BP13 has a turn-to-turn short-circuit fault, and the fault degree is calculated and analyzed according to the loss of equivalent inductance 20%, 40%, 60%, 80% and 100%. The changed synthetic characteristic harmonic impedance will change with the loss of equivalent inductance. The calculation results of its change trend are shown in Table 4 (BP11) and Table 5 (BP13).

[0156] Table 4:

[0157]

[0158]

[0159] Table 5:

[0160]

[0161] In normal operation, the filter groups on the AC side of the DC converter station can consider that 1 or 2 of the 4 BP11 and 4 BP13 groups are out of operation, and at least 3-2 parallel groups are in normal operation. Figure 3 The parameter data in Table 3 are used to establish the filter filtering and distribution change calculation and simulation circuit diagram of 12 pulsating converter valves under different 11th and 13th characteristic harmonic current states at different commutation powers.

[0162] The harmonic sources are the 11th and 13th harmonic current values ​​that each filter group may absorb under the rated operating conditions given in the project (as shown in Table 2), and the total harmonic current under the condition that at least 2 to 3 groups of the same filter groups are put into operation at the same time.

[0163] Optionally, the flow station valves can be replaced by harmonic sources to simplify the calculation.

[0164] In the actual simulation calculation process, the following conditions are set first:

[0165] 1. Since the system power supply is relatively strong, the three-phase symmetrical short-circuit current is considered to be 50kA, then the equivalent power frequency reactance value is Xs=525 / 1.732 / 50=6.06Ω, then the 11th harmonic reactance value is 66.66Ω, and the 13th harmonic reactance is 78.78Ω.

[0166] 2. Considering the manufacturing deviation of the filter reactors and capacitors in filter groups BP11 and BP13, the inductance of the reactor can be controlled within +2%, and the capacitance of the capacitor can be controlled within +1%. The corrected fundamental wave, harmonics and synthetic impedance of Tables 4 and 5 are shown in Table 6 below.

[0167] Table 6:

[0168] Harmonic Order 11 13 Fundamental reactance Ω 17.67*(100％+2％) 14.26*(100％+2％) Harmonic Reactance Ω 194.345+3.89 185.38+3.77 Fundamental capacitance Ω -2137.8*(100％-1％) -2411*((100％-1％) Harmonic capacitance Ω -194.345+1.92 -185.38+1.85 Synthetic harmonic impedance Ω 5.81 5.62

[0169] Based on this, the rated characteristic 11th and 13th harmonic current values ​​can be allocated according to the typical engineering setting (design), such as Figure 8 As shown, the simplified calculation of harmonic impedance and harmonic current distribution circuit diagram is used to calculate the change of filtering effect after a turn-to-turn short-circuit fault occurs in the BP11 or BP13 group filter reactor. Here, the harmonic source is calculated according to the percentage distribution change of 100 units.

[0170] According to Table 6 and Figure 8, the filtering effect of multiple groups (calculated according to 3 groups, or calculated according to 2 groups in parallel operation, ignoring the case of only 1 group in operation) of filters for specific harmonic currents after the occurrence of the inter-turn short-circuit fault of the filter reactor can be calculated, as well as the relationship between the distribution percentage (%) and the significant change of harmonic impedance as shown in Table 7 (the effect of filtering the 11th harmonic and the change of harmonic current distribution ratio when 3 groups of BP11 filters are running in parallel at the same time) and Table 8 (the effect of filtering the 13th harmonic and the change of distribution ratio of BP13 filters) are shown in:

[0171] Table 7:

[0172] Fault phase inductance loss (%) Power System BP11-1 BP11-2 BP11-3(fault) 0 2.82 32.39 32.39 32.39 5 4.9 56.24 56.24 -17.39 10 4.62 53.04 53.04 -10.69 20 4.5 51.69 51.69 -7.9 40 4.33 49.69 49.69 -3.71 60 4.28 49.09 49.09 -2.258 80 4.25 48.78 48.78 -1.83 100 4.23 48.6 48.6 -1.45

[0173] Table 8:

[0174] Fault phase inductance loss (%) Power System BP13-1 BP13-2 BP13-3(fault) 0 2.73 32.42 32.42 32.42 5 4.67 55.45 55.45 -15.58 10 4.44 52.71 52.71 -9.87 20 4.21 49.93 49.93 -4.08 40 4.33 49.69 49.69 -3.71 60 4.14 49.21 49.21 -2.56 80 4.12 48.88 48.88 -1.88 100 4.1 48.68 48.68 -1.48

[0175] It can be seen from Table 7 and Table 8 that as long as a filter reactor of one phase in the filter BP11 or BP13 group has a short circuit between turns, a slight inductance loss (5%-10%) occurs, and the harmonic impedance characteristics of the fault phase will change significantly. For example, if a short circuit occurs in the filter reactor of the BP11 (13)-3B phase, the result of BP11 (13)-3B with respect to absorption and filtering of specific 11th (13th) characteristic harmonics will change significantly, and this change will further cause the specific 11th (13th) characteristic harmonics to be redistributed between the parallel-operated BP11 (13)-1B, BP11 (13)-2B and BP11 (13)-3B. The change in harmonic absorption and distribution ratio is very huge. Therefore, it can be determined that, especially in the early stage of the short circuit fault, when the number of fault turns is within a few turns and the inductance loss is 5-10% (less than 5 turns), the short circuit fault can be determined.

[0176] When the inter-turn short circuit enters a rapid development stage and a large-scale short-circuit turn appears (10-20 turns), the filtering effect will change into a very stable and significant state.

[0177] Therefore, by monitoring the changes in the characteristic harmonic current content and their proportional relationship between the same phases in different groups, or the changes in the characteristic harmonic current content and their proportional relationship between different phases in the same group, it is possible to determine whether a turn-to-turn short circuit fault has occurred, and then distinguish and judge the fault group based on whether the characteristic harmonic current content change of a certain phase is relatively significantly increased (non-fault group) or significantly decreased (fault group). Taking Table 7 and Table 8 as an example, when the turn-to-turn short circuit develops to 3-5 turns, the characteristic harmonic current of the fault phase will decrease by 50-60%, while the characteristic harmonic current value of the non-fault phase will increase by about 50% or more.

[0178] In addition, for the DC transmission system, the commutation power of the converter valve is relatively stable, so the characteristic harmonics it generates are also relatively stable, and in terms of the probability of the filter reactor interturn short circuit fault, it is relatively easy to occur when the characteristic harmonic current is large. As shown in Table 2, the characteristic harmonic current value is greater than the fundamental current value, and the fundamental current remains basically unchanged during the interturn short circuit fault.

[0179] Since the 500kV AC filter adopts Y-type connection and the neutral point is grounded, when a turn-to-turn short circuit occurs in a single-phase filter reactor, only the harmonic current distribution relationship between the fault phases is affected. From Table 7 and Table 8, as well as Figure 8 It can be seen that the proportion of the characteristic 11th or 13th harmonic current absorbed and distributed between the filter BP11 or BP13 groups operating in parallel will change significantly. When the inductance loss is less than 10% at the initial stage of the fault, the equivalent harmonic reactance value becomes negative (capacitive), which has a certain amplification effect on the harmonics. When the inductance loss exceeds 10%, the fault phase of the fault group is almost not allocated the 11th or 13th characteristic harmonic current. The harmonic current reduced by the fault phase of the fault group is redistributed to the fault phase of normal operation. The harmonics absorbed and distributed by the fault phase of the non-fault group are significantly increased, and the total increase in the parallel group is equal to the smaller value.

[0180] Therefore, when multiple groups (2, 3 and 4) are connected in parallel at the same time, the characteristic harmonic current of the fault phase of the fault group changes the most, while the characteristic harmonic current of the fault phase of the non-fault group changes by 100% (2 groups connected in parallel at the same time), 50% (3 groups connected in parallel at the same time), or 33.3% (4 groups connected in parallel at the same time) of the fault phase. The characteristic harmonic absorption transformation or incremental comparison is performed for the current between the same phases of the operating filters BP11 and BP13. For the three-phase group with Y-type connection and neutral point grounding, the zero-sequence current is directly calculated.

[0181] That is to say, a reactor fault monitoring method and device disclosed in an embodiment of the present invention can determine whether a turn-to-turn short circuit fault occurs in the current bandpass filter based on the changes in the 11th or 13th characteristic harmonic values ​​in the real-time values ​​of the three-phase branch zero-sequence current of each group of bandpass filters in real time during the operation of the power system, thereby achieving the purpose of quickly, effectively and sensitively detecting reactor faults.

[0182] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0183] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0184] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for monitoring reactor fault, characterized in that: Applicable to a power system configured with a bandpass filter bank, the method comprises: For each group of band-pass filter groups, real-time values ​​of branch currents of each phase of the band-pass filter group are collected in real time; Calculate the real-time value of the three-phase branch zero-sequence current of the bandpass filter group based on the real-time value of the branch current; Calculate the mth order first characteristic harmonic value in the real-time value of the zero-sequence current of the three-phase branch, where the value of m is 11 or 13; Compare the first characteristic harmonic values ​​with set values ​​respectively, and determine that a turn-to-turn short circuit fault occurs in the reactor when a second characteristic harmonic value greater than the set value and meeting a fault occurrence condition exists among the first characteristic harmonic values; The fault occurrence condition is (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, where n refers to the nth group of bandpass filters, and the value of n is greater than or equal to 1, ΔHRI m (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI m (f) is the maximum value of the second characteristic harmonic value greater than the set value, and Idz is the set value; The first characteristic harmonic value is compared with a set value respectively, and when there is a second characteristic harmonic value greater than the set value and meeting the fault occurrence condition in the first characteristic harmonic value, it is determined that a turn-to-turn short circuit fault occurs in the reactor, including: Compare the first characteristic harmonic value obtained with a set value to obtain a second characteristic harmonic value greater than the set value; Determine the minimum value ΔHR I among the second characteristic harmonic values m (nf) and maximum ΔHRI m (f), using (0.33-1 ) ΔHRI m (f) = ΔHRI m (nf)>Idz makes a judgment; If the minimum value of the second characteristic harmonic value ΔHR I m (nf) and maximum ΔHRI m (f) Comply with (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, it is determined that the reactor has a turn-to-turn short-circuit fault.

2. The method according to claim 1, characterized in that Also includes: Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; If the number is 1, it is determined that the bandpass filter group having the second characteristic harmonic value is a faulty group.

3. The method according to claim 1, characterized in that Also includes: Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; If the number is 2, determining a first band-pass filter group and a second band-pass filter group having the second characteristic harmonic value; Respectively calculating the mth third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter; It is determined that the corresponding band-pass filter group with the smallest third characteristic harmonic value is the fault group, and the other band-pass filter group is the non-fault group.

4. The method according to claim 1, characterized in that: Also includes: Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; If the number is 2, determining a first band-pass filter group and a second band-pass filter group having the second characteristic harmonic value; The second characteristic harmonic values ​​of the first band-pass filter group and the second band-pass filter group are compared to determine that the band-pass filter group with a relatively small second characteristic harmonic value is a faulty group and the other band-pass filter group is a non-faulty group.

5. The method according to claim 1, characterized in that Also includes: Obtain the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; If the number is greater than or equal to 3, the bandpass filter group with the largest second characteristic harmonic value is determined to be a faulty group, and the bandpass filter group with other second characteristic harmonic values ​​in a set proportion to the largest second characteristic harmonic value is a non-faulty group, and the set proportion is 0.33 to 0.

5.

6. A reactor fault monitoring device, characterized in that: Applicable to a power system equipped with a bandpass filter group, the reactor fault monitoring device comprises: A real-time acquisition module, used for acquiring the real-time value of the branch current of each phase of each band-pass filter group in real time for each band-pass filter group; A calculation module, used for calculating the real-time value of the three-phase branch zero-sequence current of the bandpass filter group based on the real-time value of the branch current; and calculating the mth first characteristic harmonic value in the real-time value of the three-phase branch zero-sequence current, where the value of m is 11 or 13; A comparison module, used for comparing the first characteristic harmonic value with a set value respectively, and determining that a turn-to-turn short circuit fault occurs in the reactor when a second characteristic harmonic value greater than the set value and meeting a fault occurrence condition exists in the first characteristic harmonic value; The fault occurrence condition is (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, where n refers to the nth group of bandpass filters, and the value of n is greater than or equal to 1, ΔHR I m (nf) is the minimum value of the second characteristic harmonic value greater than the set value, ΔHRI m (f) is the maximum value of the second characteristic harmonic value greater than the set value, and Idz is the set value; The comparison module is used to compare the first characteristic harmonic value with the set value to obtain a second characteristic harmonic value greater than the set value; determine the minimum value ΔHR I of the second characteristic harmonic value m (nf) and maximum ΔHRI m (f), using (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz to judge; if the minimum value of the second characteristic harmonic value ΔHR I m (nf) and maximum ΔHRI m (f) Comply with (0.33-1)ΔHRI m (f) = ΔHRI m (nf)>Idz, it is determined that the reactor has a turn-to-turn short-circuit fault.

7. The device according to claim 6, characterized in that The device also includes: An acquisition module, used for acquiring the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; A fault locating module is configured to determine, if the number is 1, that the bandpass filter group having the second characteristic harmonic value is a faulty group.

8. The device according to claim 6, characterized in that The device also includes: An acquisition module, used to acquire the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; if the number is 2, determining a first bandpass filter group and a second bandpass filter group having the second characteristic harmonic value; The calculation module is further used to respectively calculate the mth third characteristic harmonic value in the real-time value of the branch current of each phase of the first band-pass filter group and the second band-pass filter; The fault location module determines that the corresponding band-pass filter group with the smallest third characteristic harmonic value is the fault group, and the other band-pass filter group is the non-fault group.

9. The device according to claim 6, characterized in that The device also includes: An acquisition module, used to acquire the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; if the number is 2, determining a first bandpass filter group and a second bandpass filter group having the second characteristic harmonic value; The fault location module is used to compare the second characteristic harmonic values ​​of the first bandpass filter group and the second bandpass filter group, and determine that the bandpass filter group with a relatively small second characteristic harmonic value is a faulty group and the other bandpass filter group is a non-faulty group.

10. The device according to claim 6, characterized in that The device also includes: An acquisition module, used for acquiring the number of bandpass filter groups having a second characteristic harmonic value greater than a set value and meeting a fault occurrence condition; A fault location module is used to determine that the bandpass filter group with the largest second characteristic harmonic value is a faulty group if the number is greater than or equal to 3, and the bandpass filter groups with other second characteristic harmonic values ​​in a set proportion to the maximum second characteristic harmonic value are non-faulty groups, and the set proportion is 0.33 to 0.5.

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