Sensitive equipment voltage sag fault probability evaluation method
阅读说明：本技术 一种敏感设备电压暂降故障概率评估方法 (Sensitive equipment voltage sag fault probability evaluation method ) 是由 王庆斌 蔡日 马明 吴小宁 黄辉 李钙 李晓阳 王余熙 邵彬 于 2019-08-16 设计创作，主要内容包括：本发明公开了一种敏感设备电压暂降故障概率评估方法,包括以下主要步骤,S1:获得暂降数据；S2：建立T-U坐标系,根据敏感设备电压耐受曲线,将设备电压耐受曲线坐标系划分为若干区域；S3：根据暂降数据判断电压暂降是否为三相平衡矩形电压暂降,如果电压暂降为三相平衡矩形电压暂降,则执行步骤S4；反之,则对该暂降规范化处理,得到处理后的电压暂降幅值与电压暂降持续时间；S4：根据电压暂降幅值以及电压暂降持续时间判断暂降与敏感设备电压耐受曲线的位置关系；S5：根据暂降与敏感设备电压耐受曲线的位置关系,判断电压暂降造成设备故障的概率。本发明提出的评估方法克服现有方法的不足,能够确定敏感设备电压暂降耐受能力。(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.)
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:
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:
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):
because of the existence of
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:
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: making normalized voltage sag duration T' sag＝0.5T sagAnd is and
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
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
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
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;
for the same reason, in B 2Probability of equipment failure due to regional voltage sag
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：
for the same reason, in B 3Probability of equipment failure due to regional voltage sag
wherein, in the above formula, T min<t<T max；U min<u<U max：
s 54: after the sensitive equipment is affected by the voltage sag, the failure probability can be expressed as follows:
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:
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 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:
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):
because of the existence of
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:
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: making normalized voltage sag duration T' sag＝0.5T sagAnd is and
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
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
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
wherein, T in the above formula min＜t＜T max；u＜U min；
for the same reason, in B 2Regional voltage sagProbability of equipment failure
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：
for the same reason, in B 3Probability of equipment failure due to regional voltage sag
wherein, in the above formula, T min＜t＜T max；U min＜u＜U max：
s 54: after the sensitive equipment is affected by the voltage sag, the failure probability can be expressed as follows:
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:
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