CN110780128A - Sensitive equipment voltage sag fault probability evaluation method - Google Patents

Sensitive equipment voltage sag fault probability evaluation method Download PDF

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CN110780128A
CN110780128A CN201910757000.9A CN201910757000A CN110780128A CN 110780128 A CN110780128 A CN 110780128A CN 201910757000 A CN201910757000 A CN 201910757000A CN 110780128 A CN110780128 A CN 110780128A
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voltage sag
sag
voltage
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王庆斌
蔡日
马明
吴小宁
黄辉
李钙
李晓阳
王余熙
邵彬
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Guangdong Power Grid Co Ltd
Yunfu Power Supply Bureau of Guangdong Power Grid Co Ltd
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Yunfu Power Supply Bureau of Guangdong Power Grid Co Ltd
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Abstract

The invention discloses a sensitive equipment voltage sag fault probability evaluation method, which comprises the following main steps of S1, obtaining sag data; s2: establishing a T-U coordinate system, and dividing the equipment voltage tolerance curve coordinate system into a plurality of areas according to the voltage tolerance curve of the sensitive equipment; s3: judging whether the voltage sag is a three-phase balanced rectangular voltage sag or not according to the sag data, and if the voltage sag is the three-phase balanced rectangular voltage sag, executing the step S4; otherwise, the sag is subjected to normalized processing to obtain a processed voltage sag amplitude value and a processed voltage sag duration time; s4: judging the position relation of the sag and the voltage tolerance curve of the sensitive equipment according to the voltage sag amplitude and the voltage sag duration; s5: and judging the probability of equipment failure caused by voltage sag according to the position relation between the voltage sag and the voltage tolerance curve of the sensitive equipment. The evaluation method provided by the invention overcomes the defects of the existing method and can determine the voltage sag tolerance capability of the sensitive equipment.

Description

Sensitive equipment voltage sag fault probability evaluation method
Technical Field
The invention relates to the technical field of power supply, in particular to a voltage sag fault probability evaluation method for sensitive equipment.
Background
In the existing method, aiming at unbalanced sag, non-rectangular sag or non-rectangular unbalanced sag, when the sensitive equipment fault probability caused by sag is evaluated, the existing method usually evaluates the sensitive equipment fault probability as rectangular three-phase balanced sag, and from the energy perspective, the method inevitably causes large errors and has the problem of inaccurate evaluation.
In addition, when the fault probability of the sensitive equipment caused by the voltage sag is evaluated, the emphasis is generally placed on the evaluation of the uncertainty of the voltage sag tolerance capability of the sensitive equipment, the uncertainty of the voltage sag tolerance capability of the sensitive equipment is evaluated by adopting different mathematical methods such as probability, random, fuzzy random and the like, but the above various evaluation methods can be started from the mathematical perspective, and the uncertainty of the voltage sag tolerance capability of the sensitive equipment can be characterized to a certain extent.
Disclosure of Invention
The invention provides a method for evaluating the voltage sag fault probability of sensitive equipment to overcome the defects of the prior art.
In order to solve the technical problems, the invention adopts the technical scheme that: a sensitive equipment voltage sag fault probability assessment method comprises the following steps:
s1, obtaining sag data, wherein the sag data comprise voltage sag amplitude and voltage sag duration;
s2: establishing a T-U coordinate system, and dividing the equipment voltage tolerance curve coordinate system into a plurality of areas according to the voltage tolerance curve of the sensitive equipment;
s3: judging whether the voltage sag is a three-phase balanced rectangular voltage sag or not according to the sag data, and if the voltage sag is the three-phase balanced rectangular voltage sag, executing the step S4; if the voltage sag is not a three-phase balance rectangular voltage sag, carrying out standardization processing on the sag to obtain a voltage sag amplitude value and a voltage sag duration time after the standardization processing;
s4: judging the position relation of the sag and the voltage tolerance curve of the sensitive equipment according to the voltage sag amplitude and the voltage sag duration;
s5: and judging the probability of equipment failure caused by voltage sag according to the position relation between the voltage sag and the voltage tolerance curve of the sensitive equipment.
Preferably, in the step S2, the abscissa represents the voltage sag duration t and the ordinate represents the voltage sag amplitude u in the coordinate system; the regions comprise a region A, a region B and a region C, wherein the range of the region A is a set A, and the set A comprises the region A 1And A 2；
Set A 1＝(0＜t＜T min(ii) a U > 0), set A 2＝(t≥T min；u≥U max)
The range of the B area is set B, wherein the set B comprises the set B 1、B 2And B 3；
Set B 1＝(T min＜t＜T max；0＜u＜U min)
Set B 2＝{t max(u)＞t＞T max；U min＜u＜U max}
Set B 3＝(T min＜t＜T max；U min＜u＜U max)
The range of the C area is set as C ═ T ≧ T max；0≤u≤U min)
Wherein, U minFor the minimum value of the voltage sag amplitude, U, of the sensitive device in the uncertainty region maxFor the maximum value of the voltage sag amplitude, T, of the sensitive device in the uncertainty region minFor the minimum value of the duration of the voltage sag of the sensitive device in the uncertainty region, T maxFor the maximum value of the duration of the voltage sag of the sensitive device in the uncertainty region, t max(u) represents the ultimate withstand time exhibited by the device when subjected to a voltage sag of magnitude u.
Preferably, the step 3 specifically includes the following steps:
s31: the voltage sag energy index is defined as follows:
Figure RE-GDA0002287904300000021
wherein U (T) is the voltage sag amplitude, T sagFor the duration of the voltage sag, since the expression u (t) of the amplitude of the voltage sag is not easily obtained, it is difficult to directly calculate the voltage sag energy index by the formula (1);
s 32: when calculating the rectangular voltage sag energy index, the voltage sag amplitude U (T) and the voltage sag duration T sagFor a fixed value, equation (1) is rewritten as:
E＝(1-U sag 2)×T sag(2)
wherein, U sagFor the voltage sag amplitude, the formula (2) is only suitable for the calculation of the distance-shaped voltage sag energy index;
s 33: in order to calculate the non-rectangular voltage sag energy index, the non-rectangular voltage sag energy index is calculated by using formula (3) in monitoring or accurate simulation evaluation:
Figure RE-GDA0002287904300000022
in the formula (3), the first and second groups,m is the number of detected or simulated sampling points in T time, Delta T is the time interval of adjacent sampling points, U sag(k) The voltage sag amplitude value at the Kth sampling point is obtained;
s 34: three-phase voltage sag energy index E A/B/CThe voltage sag energy index of each phase can be obtained by respectively calculating and then adding the voltage sag energy indexes, as follows: e A/B/C＝E A+E B+E C； (4)
Wherein E is A、E B、E CA, B, C three-phase voltage sag energy indexes;
s 35: respectively carrying out standardization treatment on three-phase unbalanced rectangular voltage sag, three-phase balanced non-rectangular voltage sag and three-phase unbalanced non-rectangular voltage sag to obtain corresponding normalized voltage sag amplitude U' sag。
Preferably, in the step s35, for the three-phase unbalanced rectangular voltage sag, the rectangular voltage sag duration is determined, but the three-phase voltage sag amplitudes in the sag process are not equal, and no matter which phase voltage sag amplitude is selected, the normalization processing steps are as follows:
by the formula (2) and the formula (4), there are:
Figure RE-GDA0002287904300000031
obtained by the steps
Wherein, U' sagFor normalized three-phase unbalanced rectangular voltage sag amplitude, U sag.A、U sag.B、U sag.CA, B, C three-phase rectangular voltage sag amplitudes, respectively.
Preferably, in the step s35, for a three-phase balanced non-rectangular voltage sag, the voltage sag recovery process is slow, the voltage sag duration is long, the voltage sag amplitude in the latter half of the voltage sag is high, and the influence on the device is small, if the severity of the non-rectangular voltage sag in the time dimension is measured by the non-rectangular voltage sag duration, the severity of the non-rectangular voltage sag in the time dimension is overestimated, and the specific steps of normalizing the three-phase balanced non-rectangular voltage sag are as follows:
first, the normalized non-rectangular voltage sag duration
T′ sag＝0.5T sag
According to the above formula and formulas (2) and (3):
Figure RE-GDA0002287904300000033
because of the existence of
Figure RE-GDA0002287904300000034
From the above formula, one can obtain:
Figure RE-GDA0002287904300000041
wherein M is the number of sampling points in the voltage sag duration; u shape sag(k) The voltage sag amplitude at the kth sampling point.
Preferably, in the step s35, the normalization process of the three-phase unbalanced non-rectangular voltage sag is similar to the normalization process of the three-phase balanced non-rectangular voltage sag, and the steps are as follows:
using equation (3), the three-phase unbalanced non-rectangular voltage sag energy index is:
Figure RE-GDA0002287904300000042
under the condition that the energy indexes are equal, converting three-phase unbalanced non-rectangular voltage sag into three-phase balanced rectangular voltage sag:
Figure RE-GDA0002287904300000043
s 83: making normalized voltage sag duration T' sag＝0.5T sagAnd is and
Figure RE-GDA0002287904300000044
the voltage sag amplitude is substituted into the formula to obtain the normalized voltage sag amplitude
Figure RE-GDA0002287904300000045
Preferably, in the step S4,
when the voltage sag amplitude and the voltage sag duration satisfy the set A 1Or set A 2In the condition (1), the voltage dip is in region a;
when the voltage sag amplitude and the voltage sag duration time meet the conditions of the set C, the voltage sag is located in the region C;
when the voltage sag value and the voltage sag duration time meet the set B 1In the condition (2), the voltage sag is in set B 1An area;
when the voltage sag value and the voltage sag duration time meet the set B 2In the condition (2), the voltage sag is in set B 2An area;
when the voltage sag value and the voltage sag duration time meet the set B 3In the condition (2), the voltage sag is in set B 3And (4) a region.
It should be noted that the voltage sag amplitude and the voltage sag duration in the technical solution are the voltage sag amplitude and the voltage sag duration when no normalization processing is needed; or the normalized voltage sag amplitude and the normalized voltage sag duration when the normalization processing is required.
Preferably, the step S5 specifically includes:
s 51: when the device is affected by a voltage sag in area A, due to the voltage sag in set A 1In a region of A 1Voltage sag duration of a zone less than T minThe device is subjected to A 1The probability of failure after the voltage sag of a region has an effect of
Figure RE-GDA0002287904300000051
Due to A 2Region(s)Voltage sag amplitude greater than U maxThe device is subjected to A 2The probability of failure after the voltage sag of a region has an effect of
Figure RE-GDA0002287904300000052
Therefore, the failure probability after the voltage sag influence in the area A is P tripA＝0；
s 52: when the device is affected by the voltage sag of the C region, since in the aggregate C region, the voltage sag duration of the aggregate C region is greater than T maxAnd the voltage sag amplitude is lower than U minThe sag severity is high, the equipment cannot tolerate the sag, and the fault probability of the equipment is P after the equipment is influenced by the voltage sag in the C area tripC＝1；
s 53: when the device is affected by voltage sag of the B area, the voltage sag consequence state of the device also has uncertainty due to uncertainty of the voltage endurance capability of the device;
in B 1Within the region, the voltage sag S with the same sag voltage amplitude is taken t1And S t2And S is t1Is less than S t2Voltage sag duration t 2; due to S t2Has a voltage sag duration greater than S t1Duration of voltage sag, voltage sag S t2Is of higher severity, it has a greater impact on sensitive equipment, and therefore the same equipment is being subjected to S t1And S t2Probability of equipment failure after impact
Figure RE-GDA0002287904300000053
In B 1Region, T minThe probability of the left sag causing equipment failure is 0, T maxThe probability of equipment failure due to voltage sag on the right is 1, while at T minAnd T maxThe voltage dip in between, the probability of the voltage dip causing the device failure gradually increases from 0 to 1 as the voltage dip duration t increases; it can be seen that under the condition of a certain voltage sag amplitude, the voltage sag duration is in direct proportion to the failure probability of equipment, and the voltage sag duration is in direct proportion to the failure probability of the equipmentThe sag duration may be from the sag position to T minIs represented by the distance of (1), so is at B 1In the region, when the voltage sag amplitude is constant, the sag position is T minIs proportional to the probability of equipment failure caused by sag; for the same reason, in B 1In the region, when the voltage sag lasts for a certain time, the sag position is U maxIs proportional to the probability of equipment failure caused by sag;
when the voltage sag is in an uncertain region, the severity of the voltage sag and the probability of causing equipment failure are two-dimensional functions of the voltage sag amplitude u and the voltage sag duration t, and according to the analysis, B, assuming that u and t are mutually independent random variables 1Probability of equipment failure due to regional voltage sag
Figure RE-GDA0002287904300000054
Can be given by:
Figure RE-GDA0002287904300000055
Figure RE-GDA0002287904300000056
wherein, T in the above formula min＜t＜T max；u＜U min；
Figure RE-GDA0002287904300000062
Is shown in B 1In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-GDA0002287904300000063
is shown in B 1In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
for the same reason, in B 2Regional voltage sagProbability of equipment failure
Figure RE-GDA00022879043000000616
Can be given by:
Figure RE-GDA0002287904300000064
Figure RE-GDA0002287904300000065
Figure RE-GDA0002287904300000066
wherein, in the above formula, t max(u) the ultimate withstand time exhibited by the device when subjected to a voltage sag having a voltage sag magnitude u; t is t max(u)＞t＞T max；U min＜u＜U max：
Figure RE-GDA0002287904300000067
Is shown in B 2In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-GDA0002287904300000068
is shown in B 2In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
for the same reason, in B 3Probability of equipment failure due to regional voltage sag
Figure RE-GDA0002287904300000069
Can be given by:
Figure RE-GDA00022879043000000610
Figure RE-GDA00022879043000000612
wherein, in the above formula, T min＜t＜T max；U min＜u＜U max：
Figure RE-GDA00022879043000000613
Is shown in B 3In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-GDA00022879043000000614
is shown in B 3In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
s 54: after the sensitive equipment is affected by the voltage sag, the failure probability can be expressed as follows:
Figure RE-GDA00022879043000000615
compared with the prior art, the beneficial effects are:
according to the invention, under the premise of no energy change, three-phase unbalanced rectangular voltage sag, three-phase balanced non-rectangular voltage sag and three-phase unbalanced non-rectangular voltage sag are normalized into three-phase balanced rectangular voltage sag, so that the defects of the traditional method can be effectively overcome, and the evaluation accuracy is improved. In addition, when the fault probability of the sensitive equipment caused by voltage sag is evaluated by the conventional method, the emphasis is generally placed on the evaluation of the uncertainty of the voltage sag tolerance capability of the sensitive equipment, the uncertainty of the voltage sag tolerance capability of the sensitive equipment is evaluated by adopting different mathematical methods such as fuzzy, random fuzzy and the like, but all the evaluation methods can be started from the mathematical perspective, and the uncertainty of the voltage sag tolerance capability of the sensitive equipment can be represented to a certain extent.
Drawings
FIG. 1 is a flow chart of a method for evaluating the voltage sag fault probability of a sensitive device according to the present invention;
FIG. 2 is a graph of the voltage tolerance of the sensing device of the present invention;
FIG. 3 is a three-phase balanced non-rectangular voltage sag normalization scheme of the present invention;
FIG. 4 is a three-phase unbalanced non-rectangular voltage sag normalization schematic of the present invention;
FIG. 5 is a three-phase unbalanced rectangular voltage sag normalization diagram of the present invention.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the drawings, it is only for convenience of description and simplicity of description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationships in the drawings are only used for illustrative purposes and are not to be construed as limitations of the present patent, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
The technical scheme of the invention is further described in detail by the following specific embodiments in combination with the attached drawings:
example 1
A sensitive equipment voltage sag fault probability assessment method comprises the following steps:
s1, obtaining sag data, wherein the sag data comprise voltage sag amplitude and voltage sag duration;
s2: establishing a T-U coordinate system, and dividing the equipment voltage tolerance curve coordinate system into a plurality of areas according to the voltage tolerance curve of the sensitive equipment;
s3: judging whether the voltage sag is a three-phase balanced rectangular voltage sag or not according to the sag data, and if the voltage sag is the three-phase balanced rectangular voltage sag, executing the step S4; if the voltage sag is not a three-phase balance rectangular voltage sag, carrying out standardization processing on the sag to obtain a voltage sag amplitude value and a voltage sag duration time after the standardization processing;
s4: judging the position relation of the sag and the voltage tolerance curve of the sensitive equipment according to the voltage sag amplitude and the voltage sag duration;
s5: and judging the probability of equipment failure caused by voltage sag according to the position relation between the voltage sag and the voltage tolerance curve of the sensitive equipment. Note that, the steps S1 and S2 may be interchanged.
As shown in fig. 2, in step S2, the abscissa represents the voltage sag duration t and the ordinate represents the voltage sag amplitude u in the coordinate system; the regions comprise a region A, a region B and a region C, wherein the range of the region A is a set A, and the set A comprises the region A 1And A 2；
Set A 1＝(0＜t＜T min(ii) a U > 0), set A 2＝(t≥T min；u≥U max)
The range of the B area is set B, wherein the set B comprises the set B 1、B 2And B 3；
Set B 1＝(T min＜t＜T max；0＜u＜U min)
Set B 2＝{t max(u)＞t＞T max；U min＜u＜U max}
Set B 3＝(T min＜t＜T max；U min＜u＜U max)
The range of the C area is set as C ═ Y (t ≧ Y) max；0≤u≤U min)
Wherein, U minFor the minimum value of the voltage sag amplitude, U, of the sensitive device in the uncertainty region maxFor the maximum value of the voltage sag amplitude, T, of the sensitive device in the uncertainty region minFor the minimum value of the duration of the voltage sag of the sensitive device in the uncertainty region, T maxFor the maximum value of the duration of the voltage sag of the sensitive device in the uncertainty region, t max(u) represents the ultimate withstand time exhibited by the device when subjected to a voltage sag of magnitude u.
Preferably, the step 3 specifically includes the following steps:
s31: the voltage sag energy index is defined as follows:
Figure RE-GDA0002287904300000081
wherein U (T) is the voltage sag amplitude, T sagFor the duration of the voltage sag, since the expression u (t) of the amplitude of the voltage sag is not easily obtained, it is difficult to directly calculate the voltage sag energy index by the formula (1); s 32: when calculating the rectangular voltage sag energy index, the voltage sag amplitude U (T) and the voltage sag duration T sagFor a fixed value, equation (1) is rewritten as:
E＝(1-U sag 2)×T sag(2)
wherein, U sagFor the voltage sag amplitude, the formula (2) is only suitable for the calculation of the distance-shaped voltage sag energy index; s 33: in order to calculate the non-rectangular voltage sag energy index, the non-rectangular voltage sag energy index is calculated by using formula (3) in monitoring or accurate simulation evaluation:
in formula (3), M is detected during t timeOr the number of simulated sampling points, Delta T is the time interval of adjacent sampling points, U sag(k) The voltage sag amplitude value at the Kth sampling point is obtained;
s 34: three-phase voltage sag energy index E A/B/CThe voltage sag energy index of each phase can be obtained by respectively calculating and then adding the voltage sag energy indexes, as follows: e A/B/C＝E A+E B+E C； (4)
Wherein E is A、E B、E CA, B, C three-phase voltage sag energy indexes;
s 35: respectively carrying out standardization treatment on three-phase unbalanced rectangular voltage sag, three-phase balanced non-rectangular voltage sag and three-phase unbalanced non-rectangular voltage sag to obtain corresponding normalized voltage sag amplitude U' sag。
In step s35, for the three-phase unbalanced rectangular voltage sag, the duration of the rectangular voltage sag is determined, but the three-phase voltage sag amplitudes in the sag process are not equal, and no matter which phase of the voltage sag amplitude is selected, the normalization processing steps are as follows:
by the formula (2) and the formula (4), there are:
Figure RE-GDA0002287904300000092
obtained by the steps
Figure RE-GDA0002287904300000093
Wherein, U' sagFor normalized three-phase unbalanced rectangular voltage sag amplitude, U sag.A、U sag.B、U sag.CA, B, C three-phase rectangular voltage sag amplitudes, respectively.
In addition, in step s35, in addition to the three-phase balance non-rectangular voltage sag, which is mostly caused by the large-scale inductive motor starting, the sag recovery process is slow, typically lasting about several seconds, but as can be seen from fig. 1, the amplitude is higher in the latter half of the voltage sag, and the influence on the equipment is small, for example, so as to reduce the influence on the equipmentNon-rectangular voltage sag duration T sagWhen the severity of the non-rectangular voltage sag in the time dimension is measured, the severity of the non-rectangular voltage sag in the time dimension is overestimated, and the specific steps of carrying out the normalization processing on the three-phase balanced non-rectangular voltage sag are as follows:
first, the normalized non-rectangular voltage sag duration
T′ sag＝0.5T sag
According to the above formula and formulas (2) and (3):
Figure RE-GDA0002287904300000101
because of the existence of
Figure RE-GDA0002287904300000102
From the above formula, one can obtain:
wherein M is the number of sampling points in the voltage sag duration; u shape sag(k) The voltage sag amplitude at the kth sampling point.
In addition, in step s35, the normalization process for the three-phase unbalanced non-rectangular voltage sag is similar to the normalization process for the three-phase balanced non-rectangular voltage sag, and the steps are as follows:
using equation (3), the three-phase unbalanced non-rectangular voltage sag energy index is:
under the condition that the energy indexes are equal, converting three-phase unbalanced non-rectangular voltage sag into three-phase balanced rectangular voltage sag:
s 83: after making standardizationVoltage sag duration T' sag＝0.5T sagAnd is and
Figure RE-GDA0002287904300000106
the voltage sag amplitude is substituted into the formula to obtain the normalized voltage sag amplitude
In addition, in step S4,
when the voltage sag amplitude and the voltage sag duration satisfy the set A 1Or set A 2In the condition (1), the voltage dip is in region a;
when the voltage sag amplitude and the voltage sag duration time meet the conditions of the set C, the voltage sag is located in the region C;
when the voltage sag value and the voltage sag duration time meet the set B 1In the condition (2), the voltage sag is in set B 1An area;
when the voltage sag value and the voltage sag duration time meet the set B 2In the condition (2), the voltage sag is in set B 2An area;
when the voltage sag value and the voltage sag duration time meet the set B 3In the condition (2), the voltage sag is in set B 3And (4) a region.
It should be noted that the voltage sag amplitude and the voltage sag duration in the technical solution are the voltage sag amplitude and the voltage sag duration when no normalization processing is needed; or the normalized voltage sag amplitude and the normalized voltage sag duration when the normalization processing is required.
Wherein, step S5 specifically includes:
s 51: when the device is affected by a voltage sag in area A, due to the voltage sag in set A 1In a region of A 1Voltage sag duration of a zone less than T minThe device is subjected to A 1The probability of failure after the voltage sag of a region has an effect of
Figure RE-GDA0002287904300000111
Due to A 2Voltage sag amplitude of zone greater than U maxThe device is subjected to A 2The probability of failure after the voltage sag of a region has an effect of
Figure RE-GDA0002287904300000112
Therefore, the failure probability after the voltage sag influence in the area A is P tripA＝0；
s 52: when the device is affected by the voltage sag of the C region, since in the aggregate C region, the voltage sag duration of the aggregate C region is greater than T maxAnd the voltage sag amplitude is lower than U minThe sag severity is high, the equipment cannot tolerate the sag, and the fault probability of the equipment is P after the equipment is influenced by the voltage sag in the C area tripC＝1；
s 53: when the device is affected by voltage sag of the B area, the voltage sag consequence state of the device also has uncertainty due to uncertainty of the voltage endurance capability of the device;
in B 1Within the region, the voltage sag S with the same sag voltage amplitude is taken t1And S t2And S is t1Is less than S t2Voltage sag duration t 2; due to S t2Has a voltage sag duration greater than S t1Duration of voltage sag, voltage sag S t2Is of higher severity, it has a greater impact on sensitive equipment, and therefore the same equipment is being subjected to S t1And S t2Probability of equipment failure after impact
Figure RE-GDA0002287904300000113
In B 1Region, T minThe probability of the left sag causing equipment failure is 0, T maxThe probability of equipment failure due to voltage sag on the right is 1, while at T minAnd T maxThe voltage dip in between, the probability of the voltage dip causing the device failure gradually increases from 0 to 1 as the voltage dip duration t increases; it can be seen that under the condition of a certain voltage sag amplitude, the voltage sag duration is equal to that of the voltage sagThe probability of equipment failure is proportional, and the duration of the voltage sag can be from the sag position to T minIs represented by the distance of (1), so is at B 1In the region, when the voltage sag amplitude is constant, the sag position is T minIs proportional to the probability of equipment failure caused by sag; for the same reason, in B 1In the region, when the voltage sag lasts for a certain time, the sag position is U maxIs proportional to the probability of equipment failure caused by sag;
when the voltage sag is in an uncertain region, the severity of the voltage sag and the probability of causing equipment failure are two-dimensional functions of the voltage sag amplitude u and the voltage sag duration t, and according to the analysis, B, assuming that u and t are mutually independent random variables 1Probability of equipment failure due to regional voltage sag
Figure RE-GDA0002287904300000121
Can be given by:
Figure RE-GDA0002287904300000122
Figure RE-GDA0002287904300000123
Figure RE-GDA0002287904300000124
wherein, T in the above formula min＜t＜T max；u＜U min；
Figure RE-GDA0002287904300000125
Is shown in B 1In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-GDA0002287904300000126
is shown in B 1In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
in the same way, the method for preparing the composite material,in B 2Probability of equipment failure due to regional voltage sag
Figure RE-GDA0002287904300000127
Can be given by:
Figure RE-GDA0002287904300000128
Figure RE-GDA0002287904300000129
Figure RE-GDA00022879043000001210
wherein, in the above formula, t max(u) the ultimate withstand time exhibited by the device when subjected to a voltage sag having a voltage sag magnitude u; t is t max(u)＞t＞T max；U min＜u＜U max：
Figure RE-GDA00022879043000001211
Is shown in B 2In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-GDA00022879043000001212
is shown in B 2In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
for the same reason, in B 3Probability of equipment failure due to regional voltage sag
Figure RE-GDA00022879043000001213
Can be given by:
Figure RE-GDA00022879043000001214
Figure RE-GDA00022879043000001216
wherein, in the above formula, T min＜t＜T max；U min＜u＜U max：
Figure RE-GDA00022879043000001217
Is shown in B 3In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-GDA00022879043000001218
is shown in B 3In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
s 54: after the sensitive equipment is affected by the voltage sag, the failure probability can be expressed as follows:
Figure RE-GDA00022879043000001219
it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (8)

1. A sensitive equipment voltage sag fault probability assessment method is characterized by comprising the following steps:
s1, obtaining sag data, wherein the sag data comprise voltage sag amplitude and voltage sag duration;
s2: establishing a T-U coordinate system, and dividing the equipment voltage tolerance curve coordinate system into a plurality of areas according to the voltage tolerance curve of the sensitive equipment;
s3: judging whether the voltage sag is a three-phase balanced rectangular voltage sag or not according to the sag data, and if the voltage sag is the three-phase balanced rectangular voltage sag, executing the step S4; if the voltage sag is not a three-phase balance rectangular voltage sag, carrying out standardization processing on the sag to obtain a voltage sag amplitude value and a voltage sag duration time after the standardization processing;
s4: judging the position relation of the sag and the voltage tolerance curve of the sensitive equipment according to the voltage sag amplitude and the voltage sag duration;
s5: and judging the probability of equipment failure caused by voltage sag according to the position relation between the voltage sag and the voltage tolerance curve of the sensitive equipment.
2. The method for evaluating the voltage sag fault probability of the sensitive device according to claim 1, wherein in the step S2, the abscissa represents the voltage sag duration t and the ordinate represents the voltage sag amplitude u; the regions comprise a region A, a region B and a region C, wherein the range of the region A is a set A, and the set A comprises the region A 1And A 2；
Set A 1＝(0<t<T min；U>0) Set A of 2＝(t≥T min；u≥U max)
The range of the B area is set B, wherein the set B comprises the set B 1、B 2And B 3；
Set B 1＝(T min<t<T max；0<u<U min)
Set B 2＝{t max(u)>t>T max；U min<u<U max}
Set B 3＝(T min<t<T max；U min<u<U max)
The range of the C area is set as C ═ T ≧ T max；0≤u≤U min)
Wherein, U minFor the minimum value of the voltage sag amplitude, U, of the sensitive device in the uncertainty region maxFor the maximum value of the voltage sag amplitude, T, of the sensitive device in the uncertainty region minFor the minimum value of the duration of the voltage sag of the sensitive device in the uncertainty region, T maxFor the maximum value of the duration of the voltage sag of the sensitive device in the uncertainty region, t max(u) represents the ultimate withstand time exhibited by the device when subjected to a voltage sag of magnitude u.
3. The sensitive equipment voltage sag fault probability evaluation method according to claim 2, wherein the step 3 specifically comprises the following steps:
s31 Voltage sag energy index is defined as follows:
wherein U (T) is the voltage sag amplitude, T sagFor the duration of the voltage sag, since the expression u (t) of the amplitude of the voltage sag is not easily obtained, it is difficult to directly calculate the voltage sag energy index by the formula (1);
s 32: when calculating the rectangular voltage sag energy index, the voltage sag amplitude U (T) and the voltage sag duration T sagFor a fixed value, equation (1) is rewritten as:
E＝(1-U sag 2)×T sag(2)
wherein, U sagFor the voltage sag amplitude, the formula (2) is only suitable for the calculation of the distance-shaped voltage sag energy index;
s 33: in order to calculate the non-rectangular voltage sag energy index, the non-rectangular voltage sag energy index is calculated by using formula (3) in monitoring or accurate simulation evaluation:
Figure RE-FDA0002338669320000022
in formula (3), M is the number of detected or simulated sampling points in T time, Δ T is the time interval between adjacent sampling points, U sag(k) Is the Kth samplingVoltage sag amplitude at a point;
s 34: three-phase voltage sag energy index E A/B/CThe voltage sag energy index of each phase can be obtained by respectively calculating and then adding the voltage sag energy indexes, as follows: e A/B/C＝E A+E B+E C； (4)
Wherein E is A、E B、E CA, B, C three-phase voltage sag energy indexes;
s 35: respectively carrying out standardization treatment on three-phase unbalanced rectangular voltage sag, three-phase balanced non-rectangular voltage sag and three-phase unbalanced non-rectangular voltage sag to obtain corresponding normalized voltage sag amplitude U' sag。
4. The method according to claim 3, wherein in the step s35, for the three-phase unbalanced rectangular voltage sag, the rectangular voltage sag duration is determined, but the three-phase voltage sag amplitudes during the sag are not equal, and no matter which phase voltage sag amplitude is selected, the normalization processing steps are as follows:
by the formula (2) and the formula (4), there are:
Figure RE-FDA0002338669320000023
obtained by the steps
Wherein, U' sagFor normalized three-phase unbalanced rectangular voltage sag amplitude, U sag.A、U sag.B、U sag.CA, B, C three-phase rectangular voltage sag amplitudes, respectively.
5. The method according to claim 3, wherein in the step s35, for a three-phase balanced non-rectangular voltage sag, the voltage sag recovery process is slow, the voltage sag duration is long, the voltage sag amplitude in the latter half of the voltage sag is high, the device is affected little, and if the non-rectangular voltage sag duration is used to measure the severity of the non-rectangular voltage sag in the time dimension, the severity of the non-rectangular voltage sag in the time dimension is highly estimated, and the method for evaluating the voltage sag fault probability of the sensitive device specifically comprises the following steps:
first, the normalized non-rectangular voltage sag duration
T′ sag＝0.5T sag
According to the above formula and formulas (2) and (3):
Figure RE-FDA0002338669320000031
because of the existence of
Figure RE-FDA0002338669320000032
From the above formula, one can obtain:
Figure RE-FDA0002338669320000033
wherein M is the number of sampling points in the voltage sag duration; u shape sag(k) The voltage sag amplitude at the kth sampling point.
6. The method according to claim 3, wherein in step s35, the normalization process of the three-phase unbalanced non-rectangular voltage sag is similar to the normalization process of the three-phase balanced non-rectangular voltage sag, and comprises the following steps:
using equation (3), the three-phase unbalanced non-rectangular voltage sag energy index is:
Figure RE-FDA0002338669320000034
under the condition that the energy indexes are equal, converting three-phase unbalanced non-rectangular voltage sag into three-phase balanced rectangular voltage sag:
Figure RE-FDA0002338669320000035
s 83: making normalized voltage sag duration T' sag＝0.5T sagAnd is and
Figure RE-FDA0002338669320000041
the voltage sag amplitude is substituted into the formula to obtain the normalized voltage sag amplitude
Figure RE-FDA0002338669320000042
7. The method for evaluating the voltage sag fault probability of the sensitive device according to claim 2, wherein in the step S4,
when the voltage sag amplitude and the voltage sag duration satisfy the set A 1Or set A 2In the condition (1), the voltage dip is in region a;
when the voltage sag amplitude and the voltage sag duration time meet the conditions of the set C, the voltage sag is located in the region C;
when the voltage sag value and the voltage sag duration time meet the set B 1In the condition (2), the voltage sag is in set B 1An area;
when the voltage sag value and the voltage sag duration time meet the set B 2In the condition (2), the voltage sag is in set B 2An area;
when the voltage sag value and the voltage sag duration time meet the set B 3In the condition (2), the voltage sag is in set B 3And (4) a region.
8. The method according to claim 7, wherein the step S5 specifically includes:
s 51: voltage sag when device is subjected to zone aWhen it is affected, because it is in set A 1In a region of A 1Voltage sag duration of a zone less than T minThe device is subjected to A 1The probability of failure after the voltage sag of a region has an effect of Due to A 2Voltage sag amplitude of zone greater than U maxThe device is subjected to A 2The probability of failure after the voltage sag of a region has an effect of
Figure RE-FDA0002338669320000044
Therefore, the failure probability after the voltage sag influence in the area A is P tripA＝0；
s 52: when the device is affected by the voltage sag of the C area, the voltage sag duration of the C area is longer than T in the C area maxAnd the voltage sag amplitude is lower than U minThe sag severity is high, the equipment cannot tolerate the sag, and the fault probability of the equipment is P after the equipment is influenced by the voltage sag in the C area tripC＝1；
s 53: when the device is affected by voltage sag of the B area, the voltage sag consequence state of the device also has uncertainty due to uncertainty of the voltage endurance capability of the device;
in B 1Within the region, the voltage sag S with the same sag voltage amplitude is taken t1And S t2And S is t1Is less than S t2Voltage sag duration t 2; due to S t2Has a voltage sag duration greater than S t1Duration of voltage sag, voltage sag S t2Is of higher severity, it has a greater impact on sensitive equipment, and therefore the same equipment is being subjected to S t1And S t2Probability of equipment failure after impact
Figure RE-FDA0002338669320000051
In B 1Region, T minThe temporary drop on the left causing equipment failureProbability of 0, T maxThe probability of equipment failure due to voltage sag on the right is 1, while at T minAnd T maxThe voltage dip in between, the probability of the voltage dip causing the device failure gradually increases from 0 to 1 as the voltage dip duration t increases; therefore, under the condition that the voltage sag amplitude is constant, the voltage sag duration is in direct proportion to the equipment fault probability, and the voltage sag duration can reach T from the sag position minIs represented by the distance of (1), so is at B 1In the region, when the voltage sag amplitude is constant, the sag position is T minIs proportional to the probability of equipment failure caused by sag; for the same reason, in B 1In the region, when the voltage sag lasts for a certain time, the sag position is U maxIs proportional to the probability of equipment failure caused by sag;
when the voltage sag is in an uncertain region, the severity of the voltage sag and the probability of causing equipment failure are two-dimensional functions of the voltage sag amplitude u and the voltage sag duration t, and according to the analysis, B, assuming that u and t are mutually independent random variables 1Probability of equipment failure due to regional voltage sag
Figure RE-FDA0002338669320000052
Can be given by:
Figure RE-FDA0002338669320000053
Figure RE-FDA0002338669320000054
Figure RE-FDA0002338669320000055
wherein, T in the above formula min<t<T max；u<U min； Is shown in B 1In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-FDA0002338669320000057
is shown in B 1In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
for the same reason, in B 2Probability of equipment failure due to regional voltage sag
Figure RE-FDA0002338669320000058
Can be given by:
Figure RE-FDA00023386693200000511
wherein, in the above formula, t max(u) the ultimate withstand time exhibited by the device when subjected to a voltage sag having a voltage sag magnitude u; t is t max(u)>t>T max；U min<u<U max：
Figure RE-FDA00023386693200000512
Is shown in B 2In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-FDA00023386693200000513
is shown in B 2In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
for the same reason, in B 3Probability of equipment failure due to regional voltage sag
Figure RE-FDA00023386693200000514
Can be given by:
Figure RE-FDA00023386693200000515
Figure RE-FDA0002338669320000061
Figure RE-FDA0002338669320000062
wherein, in the above formula, T min<t<T max；U min<u<U max：
Figure RE-FDA0002338669320000063
Is shown in B 3In the region, the degree of influence of the voltage sag duration on the equipment failure probability;
Figure RE-FDA0002338669320000064
is shown in B 3In the region, the degree of influence of the voltage sag amplitude on the equipment failure probability;
s 54: after the sensitive equipment is affected by the voltage sag, the failure probability can be expressed as follows:
Figure RE-FDA0002338669320000065
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CN112035527A (en) * 2020-09-08 2020-12-04 四川大学 Voltage sag sensitive equipment fault level evaluation method based on data mining
CN112285454A (en) * 2020-09-11 2021-01-29 国网天津市电力公司电力科学研究院 Voltage sag severity evaluation method based on improved energy index
CN113049928A (en) * 2021-03-10 2021-06-29 海南电网有限责任公司电力科学研究院 Sub-process failure assessment method in voltage sag of industrial process
CN114094575A (en) * 2021-11-22 2022-02-25 深圳供电局有限公司 Voltage sag tolerance level analysis method and system for sensitive equipment

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112035527A (en) * 2020-09-08 2020-12-04 四川大学 Voltage sag sensitive equipment fault level evaluation method based on data mining
CN112285454A (en) * 2020-09-11 2021-01-29 国网天津市电力公司电力科学研究院 Voltage sag severity evaluation method based on improved energy index
CN113049928A (en) * 2021-03-10 2021-06-29 海南电网有限责任公司电力科学研究院 Sub-process failure assessment method in voltage sag of industrial process
CN114094575A (en) * 2021-11-22 2022-02-25 深圳供电局有限公司 Voltage sag tolerance level analysis method and system for sensitive equipment
CN114094575B (en) * 2021-11-22 2023-11-17 深圳供电局有限公司 Voltage sag tolerance level analysis method and system for sensitive equipment

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