CN102005738B - Method for identifying healthy phase saturation based on current amplitude ratio and differential current harmonic wave - Google Patents
Method for identifying healthy phase saturation based on current amplitude ratio and differential current harmonic wave Download PDFInfo
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- CN102005738B CN102005738B CN2010105887460A CN201010588746A CN102005738B CN 102005738 B CN102005738 B CN 102005738B CN 2010105887460 A CN2010105887460 A CN 2010105887460A CN 201010588746 A CN201010588746 A CN 201010588746A CN 102005738 B CN102005738 B CN 102005738B
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Abstract
The invention provides a method for identifying healthy phase saturation based on current amplitude ratio and differential current harmonic wave. A healthy phase is braked by utilizing fault phase brake current, healthy phase differential protection is locked in healthy phase saturation, and the differential protection is opened when the differential current harmonic wave is smaller according to the characteristics of the differential current harmonic wave so as to ensure that the differential protection can release the outlet in double-phase earthfault and regional high-resistance fault. By using the method, differential misoperation in healthy phase saturation can be well prevented, and error-lock can not occur in transformational fault, developmental fault and other situations.
Description
Technical field
The present invention relates to the saturated method of discrimination of a kind of electric power system healthy phases.
Background technology
In the recent period in some regional on-the-spot actual moving process, after outside the system busbar district, single-phase fault occuring, the mutation current of passing through property appears in the healthy phases secondary circuit, and misoperation has appearred in the healthy phases current differential protection.Its principal character is: distinguish outer single-phase fault, the peaked wave electric current of several cycles appears in healthy phases.The saturated criterion of the anti-CT of domestic protection equipment for busbar is mainly to utilize secondary current correctly on progress of disease basis; be that after fault, CT can not enter saturated at once; one section linear work district is arranged; referring to Cheng Lijun etc. " research of the CT saturation detection scheme of sample-based value ". relay, 2000.28 (8): 19-21.Because healthy phases fault starting and current differential protection move simultaneously, asynchronous method (time difference method) is judged to troubles inside the sample space, there is no Blocking Differential Protection, and healthy phases is sent out trip signal, has enlarged the accident scope.
These two kinds of phenomenons are all the behaviors of healthy phases differential protection generation malfunction in the differential current protection.get rid of item by item line mutual-inductance in testing crew investigation process at the scene, increasing-aid current, the impact of the factors such as protective device and secondary circuit defective, analyze the wiring of protection and secondary circuit, check the action behavior of protective device, set about from resolving the on-the-spot Fault Recorder Information that extracts, according to on-the-spot operating current and voltage waveform, when bus or circuit generation single-phase fault, the fault phase short circuit current is not very large, 5-6 during for rated current is the left and right doubly, but DC component aperiodic with very large decay, the Current Transformer Secondary side of fault phase does not occur saturated, but the burr mutation current of the peaked wave of 2-3 cycle can appear in healthy phases, the direction of the direction of mutation current and fault phase short circuit current is substantially anti-phase, the healthy phases electric current produces distortion, the healthy phases differential current satisfies the ratio brake criterion, referring to Yuan Yubo, 5 snowy peaks, Deng Jie is clear etc. and " impact of string on differential protection mutually of current transformer three-phase current ". Automation of Electric Systems, 2010, 34 (21): 65-68.The visible processing scheme to the problems referred to above of document, be generally the saturation characteristic of current transformer carried out verification at present; Whether the wiring of paying close attention to the secondary circuit neutral point has the phenomenon of loose contact or insulation damages; Carry out type selecting in strict accordance with the protective current transformer, technical conditions; the processing method for secondary circuit such as to change to ineligible current transformer; referring to Yuan Yubo; 5 snowy peaks; Deng Jie is clear etc. and " impact of string on differential protection mutually of current transformer three-phase current ". Automation of Electric Systems; 2010,34 (21): 65-68.
Summary of the invention
Goal of the invention
The objective of the invention is: during the resolution system fault, the fault phase electric current flows through the coupling of the CT secondary side neutral line and healthy phases and causes healthy phases saturated, and time difference method is mistaken for healthy phases the problem that troubles inside the sample space causes the action of healthy phases differential protection.
Technical scheme
In order to solve above technical problem; the present invention proposes based on three-phase current amplitude proportion and harmonic waves; the saturated method of identification healthy phases CT; it is characterized in that: utilize fault phase stalling current braking healthy phases; locking healthy phases differential protection when healthy phases is saturated; simultaneously according to the harmonic waves feature at a harmonic waves hour open differential protection, when guaranteeing in double earthfault, district high resistive fault, differential protection can be opened outlet.
The operating characteristics of the Sudden Changing Rate ratio-differential relay of general current differential protection is:
ΔI
d＞I
d0 （1）
ΔI
d＞kΔI
r （2）
Δ I wherein
dBe the poor stream amplitude of Sudden Changing Rate, Δ I
rBe prominent residual quantity stalling current amplitude, I
d0Be differential startup threshold, k is proportional brake coefficient.
From the above mentioned, when healthy phases occurs when saturated, the general poor stream of healthy phases Sudden Changing Rate is larger, and with healthy phases Sudden Changing Rate stalling current sizableness, so formula (1) and formula (2) are not enough to brake.But this moment, fault phase Sudden Changing Rate stalling current was generally larger; based on these characteristics; the present invention adopts fault phase Sudden Changing Rate stalling current braking healthy phases; when the poor stream of Sudden Changing Rate during greater than a certain proportion of maximal phase Sudden Changing Rate stalling current; open differential protection; otherwise Blocking Differential Protection, as the formula (3):
ΔI
d＞k
sat1max{ΔI
rφ} （3）
Max{ Δ I wherein
rφBe maximal phase Sudden Changing Rate stalling current amplitude, k
sm1Be healthy phases saturation mutation amount restraint coefficient.
When the consideration healthy phases is saturated, the fault phase electric current flows through the pro rate relation difference of healthy phases CT secondary circuit; and fault phase Sudden Changing Rate stalling current can be decayed in time; the reliably locking in some cases of Sudden Changing Rate brake criterion; therefore the present invention adopts fault phase stable state stalling current braking healthy phases; when the poor stream of stable state during greater than a certain proportion of maximal phase stalling current; open differential protection, otherwise Blocking Differential Protection
I
d＞k
sm2max{I
rφ} （4）
Max{I wherein
rφBe maximal phase stalling current amplitude, I
dBe poor stream fundamental voltage amplitude, k
Sot2Be the saturated steady-state quantity restraint coefficient of healthy phases.
during the interior double earthfault of taking into account system generating region, fault phase electric current difference is larger, said method may cause the mistake locking, in order to reduce this risk, increase the open differentiation of harmonic waves, Main Basis is that the time dependent trend of harmonic waves content of troubles inside the sample space and the saturated formation of healthy phases is just in time opposite, troubles inside the sample space harmonic waves content can diminish by temporal evolution gradually, and the harmonic content of the poor stream of the saturated formation of healthy phases can increase gradually with changing fault time, therefore the present invention's method of adopting harmonic component in the poor stream of judgement to account for poor stream fundametal compoment ratio addresses the above problem, the harmonic component of being on duty in stream hour, open differential protection, as the formula (5)
I
dh＜kI
d (5）
I wherein
dhBe poor stream total harmonic distortion, I
dBe poor stream fundamental voltage amplitude.
The logic diagram of above method as shown in drawings.
Beneficial effect
1) brake healthy phases with fault phase, take full advantage of the saturated substantive characteristics of healthy phases, principle is simple and reliable, can reliable locking during the saturated time difference method erroneous judgement of healthy phases.
2) this method does not only affect responsiveness and the operating characteristics of the prominent poor relay of normal fault, can also well prevent misoperation differential when healthy phases is saturated, can not miss locking in situations such as evolved fault, developing faults.
3) utilize harmonic waves open, differential protection operating characteristics when not affecting evolved fault, when turning in troubles inside the sample space, district high resistive fault outside the bus district occurs, can Blocking Differential Protection.
Description of drawings
Accompanying drawing is the logic diagram of the saturated differentiation of healthy phases CT of the present invention.
Embodiment
Embodiment below in conjunction with a half breaker bus mode of connection is described in further detail the present invention.But the invention is not restricted to given example.
1) AC sampling: the current sampling data that obtains each branch road of bus.
2) calculate each branch current Sudden Changing Rate Δ I
i, i=1,2 ... n, i sign branch road number.
3) calculate each branch current fundametal compoment I
i, i=1,2 ... n, i sign branch road number.
4) calculate the poor stream of bus three-phase Sudden Changing Rate
The Sudden Changing Rate stalling current
The poor stream of stable state
The stable state stalling current
5) calculate poor stream total harmonic distortion, computing formula is:
I
DrmsBe the root mean square value of poor stream, I
dcBe the DC component of poor stream, I
dBe poor stream fundamental voltage amplitude.
6) when system's generation disturbance, differential protection as non-latching in time difference method, Sudden Changing Rate ratio differential condition satisfies (Δ I
d＞I
d0, Δ I
d＞k Δ I
r), Δ I
d＞k
Sot1Max{ Δ I
rφCondition satisfies, and satisfies simultaneously I
d＞k
sm2Max{I
rφOr I
dh＜kI
d, open differential relay, otherwise the locking differential relay.
Claims (1)
1. based on current amplitude ratio and the saturated method of harmonic waves identification healthy phases, it is characterized in that, comprise the following steps:
1) AC sampling: the current sampling data that obtains each branch road of bus;
2) calculate each branch current Sudden Changing Rate Δ I
i, i=1,2 ... n, i sign branch road number;
3) calculate each branch current fundametal compoment I
i, i=1,2 ... n, i sign branch road number;
4) calculate the poor stream of bus three-phase Sudden Changing Rate
The Sudden Changing Rate stalling current
The poor stream of stable state
The stable state stalling current
Wherein,
5) calculate poor stream total harmonic distortion, computing formula is:
I
DrmsBe the root mean square value of poor stream, I
dcBe the DC component of poor stream, I
dBe poor stream fundamental voltage amplitude;
6) when system's generation disturbance, differential protection as non-latching in time difference method satisfies Δ I simultaneously
d＞I
d0,
And satisfy
And I
dh＜kI
dOne of the time, open differential relay, otherwise locking differential relay, wherein, Δ I
dBe the poor stream amplitude of Sudden Changing Rate, Δ I
rBe prominent residual quantity stalling current amplitude, I
d0Be differential startup threshold, k is proportional brake coefficient;
Be maximal phase Sudden Changing Rate stalling current amplitude, k
Sat1Be healthy phases saturation mutation amount restraint coefficient,
Be maximal phase stalling current amplitude, k
Sat2Be the saturated steady-state quantity restraint coefficient of healthy phases.
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| CN102005738B true CN102005738B (en) | 2013-11-06 |
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| CN102279338B (en) * | 2011-04-29 | 2013-09-25 | 上海磁浮交通发展有限公司 | Method for monitoring two-phase grounding fault of magnetic levitation stator coil |
| CN103326329B (en) * | 2013-07-04 | 2016-02-03 | 南华大学 | The guard method of CT asymmetric broken string quick lock bus |
| CN103529321B (en) * | 2013-10-10 | 2016-01-20 | 长园深瑞继保自动化有限公司 | CT saturation detection method |
| CN105024356B (en) * | 2014-06-19 | 2018-05-29 | 许继电气股份有限公司 | A kind of 35kV and following voltage class ratiometric dynamic formula bus bar protecting method |
| CN109375131B (en) * | 2018-07-31 | 2022-03-04 | 中国电力科学研究院有限公司 | Method and system for identifying saturation speed and saturation depth of current transformer |
| CN109768526B (en) * | 2019-03-13 | 2020-09-04 | 南京南瑞继保电气有限公司 | Method and device for identifying non-fault phase saturation based on current distribution coefficient |
| CN112782494B (en) * | 2019-11-05 | 2023-10-17 | 南京南瑞继保电气有限公司 | Saturation identification method and device for shunt reactor |
| CN110927523A (en) * | 2019-11-29 | 2020-03-27 | 国电南瑞科技股份有限公司 | Fault positioning method for flexible direct-current power distribution network |
| CN111490531B (en) * | 2020-03-02 | 2021-07-13 | 国电南瑞科技股份有限公司 | Power transmission line distance protection current transformer saturation identification method and system |
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