CN109521304B - Method and device for describing and evaluating node voltage sag tolerance characteristics - Google Patents

Method and device for describing and evaluating node voltage sag tolerance characteristics Download PDF

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CN109521304B
CN109521304B CN201811500361.7A CN201811500361A CN109521304B CN 109521304 B CN109521304 B CN 109521304B CN 201811500361 A CN201811500361 A CN 201811500361A CN 109521304 B CN109521304 B CN 109521304B
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voltage sag
grade
severity
sag
node
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唐钰政
刘书铭
代双寅
张博
朱明丽
王毅
李琼林
汪坤
徐永海
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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Abstract

The application relates to a description method and an evaluation method and device for node voltage sag tolerance characteristics. And then the severity of the voltage sag of the node can be conveniently evaluated according to the quantization index.

Description

Method and device for describing and evaluating node voltage sag tolerance characteristics
Technical Field
The invention belongs to the technical field of transient power quality analysis, and particularly relates to a method and a device for describing and evaluating node voltage sag tolerance characteristics.
Background
With the increasing sensitivity of consumers in the grid and users to power quality problems, voltage sag has become one of the most serious power quality problems. In particular, by using precision control and measurement equipment of computers, power electronics and microelectronic technologies, new energy power generation equipment and the like, voltage sag events can cause serious economic losses in the aspects of equipment production, operation and the like.
The voltage sag tolerance curve is an important measure for measuring the voltage sag tolerance capability, and in order to describe the voltage sag tolerance capability of the IT Industry and the semiconductor Industry, the american society for computer and commercial Equipment Manufacturers CBEMA (computer Business Equipment Manufacturers association), the information Technology Industry association ITIC (information Technology Industry council), and the international association for semiconductor Equipment and Materials SEMI (semiconductor Equipment and Materials international) have proposed the voltage sag tolerance curves CBEMA, ITIC, and SEMI F47 in succession. With the progress of research, researchers found that the voltage dip receptor is mainly sensitive equipment, and since the tolerance characteristics of sensitive equipment are influenced by various factors, the voltage tolerance curves of four typical sensitive equipment with uncertain regions are given in the IEEE1346-1998 standard and the report of C4.110. Once the voltage sag event exceeds the tolerance of these curves, it can lead to the failure of the consumer. However, for a node, the types of loads accessed by the node are various, and the single tolerance curve of the industry standard or a certain equipment tolerance curve containing an uncertain region is used for describing the tolerance capability of the node to the voltage sag, so that the tolerance characteristic of the node cannot be sufficiently reflected, and even the node tolerance capability is described improperly, which affects the accuracy of the power quality evaluation result of the node.
In addition, the existing voltage sag evaluation system can be divided into a system disturbance level and a device immunity level: the severity of the voltage sag event is directly evaluated only according to the voltage sag event characteristics of the power grid side, and the severity of the voltage sag event is evaluated by considering the tolerance condition of equipment on the basis of the voltage sag event characteristics. The system disturbance level reflects the quality of power supply electric energy of a system side based on the characteristic quantity of the voltage sag event, but the tolerance capability of sensitive equipment is not considered, only two characteristic quantities of the sag amplitude and the duration are considered, and two characteristic quantities of a starting point and phase jump are ignored; the device immunity level reflects the situation where the device is able to tolerate voltage sags. The comprehensive severity evaluation of the voltage sag comprises the severity of the sag event and the sensitivity of equipment, a plurality of quantitative indexes reflect the comprehensive severity of the voltage sag according to the compatibility of the system disturbance level and the equipment immunity level, but the solving process is complicated and is not suitable for the voltage sag evaluation of an actual system.
Therefore, the invention provides a method for describing and evaluating the voltage sag tolerance characteristics of a node, which fully considers the diversity and complexity of the access load of the node and reasonably describes the voltage sag tolerance capability of the node.
Disclosure of Invention
In order to more accurately describe the voltage sag tolerance capability of the node and improve the accuracy of the node power quality evaluation result, the invention provides a description and evaluation method of the node voltage sag tolerance characteristic.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention provides a method for describing and evaluating the voltage sag tolerance characteristics of a node, which comprises the following steps:
s1: obtaining a sag amplitude v in a voltage sag event1Duration v of time2Starting point v3And phase jump v4；
S2: for v1、v2、v3And v4Respectively obtained values v subjected to non-dimensionalization1’、v2’、v3' and v4’，
Figure BDA0001896858890000031
vimaxIndicating the corresponding sag amplitude value and,the duration, the maximum value of the value range of the starting point and the phase jump, namely the sag amplitude is 0.9, the duration is 1000ms, the starting point and the phase jump are 90 degrees, and i is an integer which is more than or equal to 1 and less than or equal to 4;
s3: the association matrix K is established and,
Figure BDA0001896858890000032
kij＝vi' -a when vi’∈(ai，j,ai，j+1]
Figure BDA0001896858890000033
When in use
Figure BDA0001896858890000034
j is an integer of 1 to 5 inclusive,
wherein, ai，jAnd ai，j+1The value ranges are set according to the severity and corresponding to the sag amplitude, the duration, the starting point and the phase jump after the dimensionless processing;
s4: and multiplying the weight matrix W by the correlation matrix K according to the sag amplitude, the duration, the starting point and the phase jump weight matrix W, and evaluating the node voltage sag severity according to the result.
Preferably, the method for describing and evaluating the node voltage sag tolerance characteristics of the invention,
a1，1＝1，a1，2＝0.844，a1，3＝0.611，a1，4＝0.389，a1，5＝0.167，a1，6＝0，
a2，1＝1，a2，2＝0.994，a2，3＝0.760，a2，4＝0.525，a2，5＝0.290，a2，6＝0，
a3，1＝1，a3，2＝0.556，a3，3＝0.444，a3，4＝0.222，a3，5＝0.111，a3，6＝0，
a4，1＝1，a4，2＝0.556，a4，3＝0.444，a4，4＝0.222，a4，5＝0.111，a4，6＝0。
preferably, in the method for describing and evaluating the node voltage sag tolerance characteristics of the present invention, P ═ WK is calculated to obtain P ═ P [ -P ═ WK1 P2 P3 P4 P5]Wherein the weight matrix W ═ 0.55550.25950.11610.0542]。
Preferably, in the method for describing and evaluating the node voltage sag tolerance characteristic of the present invention, when the evaluation is performed, the voltage sag severity evaluation value S is MAX (P)1,P2,P3,P4,P5)；
When S belongs to (0.75, 1), the comprehensive grade level of the severity of the node voltage sag is I grade,
when the S belongs to (0.25, 0.75), the comprehensive grade level of the severity of the node voltage sag is grade II,
when the S is the [ -0.25,0.25], the node voltage sag severity comprehensive grade level is grade III,
when the S is equal to [ -0.75, -0.25), the comprehensive grade level of the severity of the node voltage sag is IV grade,
when Seege [ -1, -0.75), the node voltage sag severity composite grade level is grade V, and the severity of grade level increases from grade I to grade V.
Preferably, the method for describing and evaluating the node voltage sag tolerance characteristics of the invention,
if the voltage sag event is an integral event and occurs for multiple times, calculating
Figure BDA0001896858890000041
Where N is the number of voltage sag events occurring, N1、n2、n4、n5The times that the node voltage sag severity comprehensive grade levels are respectively grade I, grade II, grade IV and grade V are used, and the judgment standard of S and the S are used for evaluating the node voltage sag severity comprehensive grade levels of the whole eventThe same judgment criteria apply.
The invention also provides a device for describing and evaluating the node voltage sag tolerance characteristics, which comprises:
a data acquisition module: for obtaining sag amplitude v in voltage sag event1Duration v of time2Starting point v3And phase jump v4；
Dimensionless processing module, pair v1、v2、v3And v4Respectively obtained values v subjected to non-dimensionalization1’、v2’、v3' and v4’，
Figure BDA0001896858890000051
vimaxThe maximum values of the value ranges of the corresponding sag amplitude, the duration, the starting point and the phase jump are represented, namely the sag amplitude is 0.9, the duration is 1000ms, the starting point and the phase jump are changed into 90 degrees, and i is an integer which is more than or equal to 1 and less than or equal to 4;
an incidence matrix establishing module for establishing an incidence matrix K,
Figure BDA0001896858890000052
kij＝vi' -a when vi’∈(ai，j,ai，j+1]
Figure BDA0001896858890000053
When in use
Figure BDA0001896858890000054
j is an integer of 1 to 5, wherein ai，jAnd ai，j+1The value ranges are set according to the severity and corresponding to the sag amplitude, the duration, the starting point and the phase jump after the dimensionless processing;
an evaluation module: and multiplying the weight matrix W by the correlation matrix K according to the sag amplitude, the duration, the starting point and the phase jump weight matrix W, and evaluating the node voltage sag severity according to the result.
Preferably, the node voltage sag tolerance characteristic description and evaluation method of the invention is implemented in the correlation matrix building module
a1，1＝1，a1，2＝0.844，a1，3＝0.611，a1，4＝0.389，a1，5＝0.167，a1，6＝0，
a2，1＝1，a2，2＝0.994，a2，3＝0.760，a2，4＝0.525，a2，5＝0.290，a2，6＝0，
a3，1＝1，a3，2＝0.556，a3，3＝0.444，a3，4＝0.222，a3，5＝0.111，a3，6＝0，
a4，1＝1，a4，2＝0.556，a4，3＝0.444，a4，4＝0.222，a4，5＝0.111，a4，6＝0。
Preferably, the present invention provides a method for describing and evaluating the node voltage sag tolerance characteristics, wherein in the evaluation module, P ═ WK is calculated to obtain P ═ P1 P2 P3 P4 P5]Wherein the weight matrix W ═ 0.55550.25950.11610.0542]。
Preferably, in the node voltage sag tolerance characteristic description and evaluation method of the present invention, the evaluation module has a voltage sag severity evaluation value S ═ MAX (P ═ MAX) (P1,P2,P3,P4,P5)；
When S belongs to (0.75, 1), the comprehensive grade level of the severity of the node voltage sag is I grade,
when the S belongs to (0.25, 0.75), the comprehensive grade level of the severity of the node voltage sag is grade II,
when the S is the [ -0.25,0.25], the node voltage sag severity comprehensive grade level is grade III,
when the S is equal to [ -0.75, -0.25), the comprehensive grade level of the severity of the node voltage sag is IV grade,
when Seege [ -1, -0.75), the node voltage sag severity composite grade level is grade V, and the severity of grade level increases from grade I to grade V.
Preferably, the method for describing and evaluating the voltage sag tolerance characteristics of the node further includes an overall event evaluation module, configured to evaluate when the voltage sag event is an overall event, and calculate
Figure BDA0001896858890000061
Where N is the number of voltage sag events occurring, N1、n2、n4、n5The times that the node voltage sag severity comprehensive grade levels are respectively grade I, grade II, grade IV and grade V are used for evaluating the node voltage sag severity comprehensive grade levels of the whole event
Figure BDA0001896858890000062
The judgment criterion of (2) is the same as that of (S).
The invention has the beneficial effects that:
the invention discloses a method and a device for describing and evaluating the tolerance characteristics of node voltage sag. And then the severity of the voltage sag of the node can be conveniently evaluated according to the quantization index.
Drawings
The technical solution of the present application is further explained below with reference to the drawings and the embodiments.
Fig. 1 is a flowchart of a method for describing and evaluating voltage sag tolerance characteristics of a node according to an embodiment of the present invention.
FIG. 2a, FIG. 2b, FIG. 2c, and FIG. 2d are tolerance curves of four typical sensing devices, ASD, PLC, AC Relay, and PC, respectively, according to an embodiment of the present invention;
FIG. 3 is a tolerance curve for a node with uncertainty regions formed in accordance with an embodiment of the present invention.
Fig. 4 is a diagram illustrating a voltage sag tolerant area of a node according to an embodiment of the present invention.
Fig. 5a and 5b are graphs showing the sag starting point and the phase jump, respectively, according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The technical solutions of the present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Examples
The present embodiment provides a method for describing and evaluating voltage sag tolerance characteristics of a node, as shown in fig. 1, including the following steps:
s1: obtaining a sag amplitude v in a voltage sag event1Duration v of time2Starting point v3And phase jump v4；
S2: for v1、v2、v3And v4Respectively obtained values v subjected to non-dimensionalization1’、v2’、v3' and v4’，
Figure BDA0001896858890000081
vimaxThe maximum values of the value ranges of the corresponding sag amplitude, the duration, the starting point and the phase jump are represented, namely the sag amplitude is 0.9, the duration is 1000ms, the starting point and the phase jump are changed into 90 degrees, and i is an integer which is more than or equal to 1 and less than or equal to 4;
s3: the association matrix K is established and,
Figure BDA0001896858890000082
kij＝vi' -a when vi’∈(ai，j,ai，j+1]
Figure BDA0001896858890000083
When in use
Figure BDA0001896858890000084
j is an integer of 1 to 5 inclusive,
wherein, ai，jAnd ai，j+1The value ranges are set according to the severity and corresponding to the sag amplitude, the duration, the starting point and the phase jump after the dimensionless processing;
s4: and multiplying the weight matrix W by the correlation matrix K according to the sag amplitude, the duration, the starting point and the phase jump weight matrix W, and evaluating the node voltage sag severity according to the result.
Further, the air conditioner is provided with a fan,
a1，1＝1，a1，2＝0.844，a1，3＝0.611，a1，4＝0.389，a1，5＝0.167，a1，6＝0，
a2，1＝1，a2，2＝0.994，a2，3＝0.760，a2，4＝0.525，a2，5＝0.290，a2，6＝0，
a3，1＝1，a3，2＝0.556，a3，3＝0.444，a3，4＝0.222，a3，5＝0.111，a3，6＝0，
a4，1＝1，a4，2＝0.556，a4，3＝0.444，a4，4＝0.222，a4，5＝0.111，a4，6＝0。
an example of a calculation is:
k11＝v1' -0.844 when v1’∈(0.844,1]
Wherein
Figure BDA0001896858890000091
When in use
Figure BDA0001896858890000092
k12＝v2' -0.611, when v2’∈(0.611,0.844]
Figure BDA0001896858890000093
When in use
Figure BDA0001896858890000094
k13＝v3' -0.389, when v3’∈(0.389,0.611]
Figure BDA0001896858890000095
(0.389,0.611]… … calculation of other values is made with reference to the above example.
Further, calculating P ═ WK yields P ═ P1 P2 P3 P4 P5]Wherein the weight matrix W ═ 0.55550.25950.11610.0542]。
Further, when the evaluation is performed, the voltage sag severity evaluation value S is MAX (P)1,P2,P3,P4,P5)；
When S belongs to (0.75, 1), the comprehensive grade level of the severity of the node voltage sag is I grade,
when the S belongs to (0.25, 0.75), the comprehensive grade level of the severity of the node voltage sag is grade II,
when the S is the [ -0.25,0.25], the node voltage sag severity comprehensive grade level is grade III,
when the S is equal to [ -0.75, -0.25), the comprehensive grade level of the severity of the node voltage sag is IV grade,
when Seege [ -1, -0.75), the node voltage sag severity composite grade level is grade V, and the severity of grade level increases from grade I to grade V.
Further, if the voltage sag event is a whole event and occurs for multiple times, then the calculation is performed
Figure BDA0001896858890000101
Where N is the number of voltage sag events occurring, N1、n2、n4、n5The times that the node voltage sag severity comprehensive grade levels are respectively grade I, grade II, grade IV and grade V are used for evaluating the node voltage sag severity comprehensive grade levels of the whole event
Figure BDA0001896858890000102
The judgment criterion of (2) is the same as that of (S).
The present embodiment further provides a device for describing and evaluating voltage sag tolerance characteristics of a node, including:
a data acquisition module: for obtaining sag amplitude v in voltage sag event1Duration v of time2Starting point v3And phase jump v4；
Dimensionless processing module, pair v1、v2、v3And v4Respectively obtained values v subjected to non-dimensionalization1’、v2’、v3' and v4’，
Figure BDA0001896858890000103
vimaxThe maximum values of the value ranges of the corresponding sag amplitude, the duration, the starting point and the phase jump are represented, namely the sag amplitude is 0.9, the duration is 1000ms, the starting point and the phase jump are changed into 90 degrees, and i is an integer which is more than or equal to 1 and less than or equal to 4;
an incidence matrix establishing module for establishing an incidence matrix K,
Figure BDA0001896858890000104
kij＝vi' -a when vi’∈(ai，j,ai，j+1]
Figure BDA0001896858890000105
When in use
Figure BDA0001896858890000106
j is an integer of 1 to 5, wherein ai，jAnd ai，j+1The value ranges are set according to the severity and corresponding to the sag amplitude, the duration, the starting point and the phase jump after the dimensionless processing;
an evaluation module: and multiplying the weight matrix W by the correlation matrix K according to the sag amplitude, the duration, the starting point and the phase jump weight matrix W, and evaluating the node voltage sag severity according to the result.
Preferably, the incidence matrix establishing module
a1，1＝1，a1，2＝0.844，a1，3＝0.611，a1，4＝0.389，a1，5＝0.167，a1，6＝0，
a2，1＝1，a2，2＝0.994，a2，3＝0.760，a2，4＝0.525，a2，5＝0.290，a2，6＝0，
a3，1＝1，a3，2＝0.556，a3，3＝0.444，a3，4＝0.222，a3，5＝0.111，a3，6＝0，
a4，1＝1，a4，2＝0.556，a4，3＝0.444，a4，4＝0.222，a4，5＝0.111，a4，6＝0。
Preferably, in the evaluation module, calculating P ═ WK yields P ═ P1 P2 P3 P4 P5]Wherein the weight matrix W ═ 0.55550.25950.11610.0542]。
Preferably, in the evaluation module, the voltage sag severity evaluation value S is MAX (P)1,P2,P3,P4,P5)；
When S belongs to (0.75, 1), the comprehensive grade level of the severity of the node voltage sag is I grade,
when the S belongs to (0.25, 0.75), the comprehensive grade level of the severity of the node voltage sag is grade II,
when the S is the [ -0.25,0.25], the node voltage sag severity comprehensive grade level is grade III,
when the S is equal to [ -0.75, -0.25), the comprehensive grade level of the severity of the node voltage sag is IV grade,
when Seege [ -1, -0.75), the node voltage sag severity composite grade level is grade V, and the severity of grade level increases from grade I to grade V.
Preferably, the system further comprises an overall event evaluation module for evaluating when the voltage sag event is an overall event, and then calculating
Figure BDA0001896858890000111
Where N is the number of voltage sag events occurring, N1、n2、n4、n5The node voltage sag severity comprehensive grade levels are respectively the times of grade I, grade II, grade IV and grade V, and the judgment standard of S is the same as the judgment standard of S when the node voltage sag severity comprehensive grade levels of the whole event are evaluated.
The derivation by the scheme of this embodiment is as follows:
a1: forming a tolerance curve of the node with an uncertain region
In the embodiment, based on the tolerance curve with the node containing the uncertainty region formed by the variable frequency speed regulator, the programmable logic controller, the ac contactor and the PC, the voltage tolerance curves of the four sensitive devices are directly obtained by IEEE 1346-plus 1998 standard, and are respectively and uniquely represented by the sets {0.82, 0.60, 15, 85}, {0.77, 0.47, 15, 615}, {0.78, 0.60, 10, 35} and {0.80, 0.50, 30, 85} as shown in fig. 2a, 2b, 2c and 2d, wherein the unit of the first two numbers in each set is p.u., and the unit of the last two numbers is ms; the tolerance curve of the node with the uncertainty region can be uniquely represented by the set {0.82, 0.47, 10, 615}, as shown in fig. 3.
A2: and dividing an uncertain region of the node voltage sag tolerance characteristics to form a description graph of the node voltage sag tolerance capability.
Taking U'max、U'minAnd T'max、T'min3 equally divided points U in between1、U2And T1、T2(for this example, U1、U2And T1、T2Approximately 0.70, 0.58 and 215, 415), respectively), by U1、T1And U2、T2Rectangular tolerance curves are respectively formed, the whole VT plane is divided into A, B, C, D, E five regions, and a node voltage sag tolerance region description diagram is formed, as shown in FIG. 4. Obviously, the node voltage sag tolerance reflected by the five regions a to E decreases in order.
In a specific embodiment, in step B of the method for describing and evaluating the node voltage sag tolerance characteristics according to the present invention, the method for evaluating the severity of the node voltage sag includes:
b1, dividing the grade interval of each characteristic quantity of voltage sag
According to the description chart of the voltage sag tolerance capability of the node A in the step A, U is usedmax、U1、U2、UminDividing the sag range of 0-0.9 into 5 grades with increasing severity degree in I-V grade as a division point, and taking T as a Tmax、T1、T2、TminDividing the duration range of 0-1000 ms into 5 grades with increasing severity levels of I-V level as a division point; according to the voltage sag event sag starting point and phase jump distribution diagram in the power grid of fig. 5a and 5b, based on the idea that the distribution is denser and the influence degree is higher, the starting point interval [0 °,90 °) is divided into 5 grades with increasing severity in stages i to v according to the distribution probability [0, 2%), [ 2%, 4%, [ 4%, 6%, [ 6%, 8%), [ 8%, ∞) and the 0 ° 90 ° is divided into 5 grades with increasing severity in stages i to v according to the distribution probability [0, 1%), [ 1%, 2%), [ 2%, 5%, [ 5%, 10%, ∞) and the 0 ° 90 ° is divided into 5 grades with increasing severity in stages i to v according to the distribution probability [0, 1%, [ 1%, 2%, 5. The results of the classification of the rank intervals of these four feature quantities are shown in table 1.
TABLE 1 respective characteristic quantity class intervals
Figure BDA0001896858890000131
Because the dimension and magnitude of each index are different, in order to facilitate calculation and comparison between indexes, each index is normalized, firstly, the per-unit value of each index is processed, and divided by the maximum value of each index, and the expression is as follows:
Figure BDA0001896858890000132
in the formula: x is the number ofimaxThe maximum value of the index is shown.
And after the measured values are subjected to per unit treatment, normalization treatment is carried out on each index dimension.
The sag amplitude and the phase jump are indexes which are better when the measured value is larger, and an expression adopted in normalization is as follows:
Figure BDA0001896858890000141
the duration and the starting point are indexes that the measured value is better, and the expression adopted in the normalization is as follows:
Figure BDA0001896858890000142
in the formula: x'imaxAnd x'iminAnd the unit values respectively represent the maximum value and the minimum value of the index.
After the normalization process, the level sections of the respective feature quantity indexes are shown in table 2.
TABLE 2 evaluation index Interval Range partitioning Range (dimensionless)
Figure BDA0001896858890000143
B2, constructing a voltage sag evaluation model
The invention adopts the extension theory to establish a voltage sag severity evaluation model.In the voltage sag estimation system, the state component R ═ (N, c, v) is divided into 5 grades, corresponding to five grades I to v, and the severity increases in sequence. The object N to be estimated has 4 features c ═ c1,c2,c3,c4And v is determined by N and c together, wherein v is equal to { v1, v2, v3, v4 }. The voltage sag state object element is shown as the following formula:
Figure BDA0001896858890000144
the range of each voltage sag severity level taken with respect to the corresponding characteristic quantity is a classical domain, which is expressed as
Figure BDA0001896858890000151
In the formula: r'iSeverity of voltage sag of grade i, (a)i1,bi1) And represents the value range of each characteristic quantity under the grade.
The maximum interval range of the values of the characteristic quantities is a node region, and for the voltage sag evaluation system, the node region can be expressed as
Figure BDA0001896858890000152
The measured data of a group of voltage sag characteristic quantities represented by the object elements is the object element to be estimated, and the following formula is shown:
Figure BDA0001896858890000153
in the formula: v. ofkiIs the measured value of each characteristic quantity of the object to be evaluated.
B3 construction of correlation function
After the object element to be estimated, the classical domain and the section domain of the voltage sag estimation system are determined, a quantitative value of the relation between the object element to be estimated and the classical domain and the section domain can be obtained by using an extension association function. The correlation function value has positive or negative values, the signs of the positive and negative values indicate whether the object element to be estimated has the property, the magnitude of the correlation function value reflects the degree of having or not having the property, and the correlation function value is 0, which belongs to the critical condition of having or not having the property. Through the association function, the association degree of any element and the interval can be quantitatively described, and for elements in the same range, different hierarchies can be distinguished through the size of the association function.
The correlation function of the topology is shown in formulas (1) to (2):
Figure BDA0001896858890000161
Figure BDA0001896858890000162
Figure BDA0001896858890000163
in the formula: x is the number of0Is an optimum value when x is x0The function achieves the best effect, but x0Can not be in the interval X0At the midpoint of (a, b) (each level range section), ρ (X, X)0) And ρ (X, X) are respectively the point X with respect to the interval X0The distance between (a, b) and (X) is (c, d) (the maximum range section in which each feature can be taken). ρ (x, x)0,X0) Left side distance or right side distance, depending on the optimum value x0In the interval X0Position in (a, b), the optimum value is b, hence the right side distance, i.e. for the voltage sag estimation system herein
Figure BDA0001896858890000164
And (3) according to the formula (2), the correlation function value of the measured data of each characteristic quantity of the object element to be estimated in each evaluation grade classical domain can be obtained, so as to represent the correlation degree between the object element to be estimated and each index and each grade. An n × m correlation matrix is established through correlation function values of the measured data of each feature quantity in each evaluation level classical domain, as shown in formula (5), wherein n represents the number of evaluation indexes (i.e. the number of feature quantities), and m represents the number of evaluation grades. Herein n and m are 4 and 5, respectively.
Figure BDA0001896858890000165
B4, obtaining the weight of each characteristic index
The weight of each characteristic quantity is obtained by adopting an improved analytic hierarchy process, which comprises the following specific steps:
1) and (4) solving a comparison matrix of the voltage sag characteristic quantity by adopting a three-scale method. According to the contribution degree of each voltage sag characteristic quantity to the equipment, obtaining a corresponding comparison matrix A:
Figure BDA0001896858890000171
in the formula:
Figure BDA0001896858890000172
at present, the sag amplitude and the duration are generally considered as main characteristic quantities of voltage sag, and it can be seen from the definition of voltage sag that the sag amplitude is the most important criterion of voltage sag, while the starting point and the phase jump only affect a small part of devices, and some studies indicate that the phase jump has a smaller influence than the sag starting point. Therefore, when the comparison matrix is constructed, the size relationship of the influence degrees of different sag characteristic quantities is considered as follows: sag amplitude > duration > start point > phase jump.
2) Calculating the importance ranking index of the comparison matrix A according to the formula
Figure BDA0001896858890000173
3) Constructing a judgment matrix B of the voltage sag characteristic quantity as (B)ij)n×nThe calculation formula is
Figure BDA0001896858890000174
In the formula: r ismax＝max(r1,r2,…,rn)，rmin＝min(r1,r2,…,rn)。
4) Obtaining a pseudo-optimal consistent matrix B ' ═ B ' of the judgment matrix of the voltage sag characteristic quantity 'ij)n×nThe calculation formula is
Figure BDA0001896858890000181
In the formula: c. Cij＝lgbij。
5) Obtaining a matrix T ═ T (T) from the pseudo-optimal consistent matrix Bij)n×nThe calculation formula is
Figure BDA0001896858890000182
Then, the row vectors of the matrix T are added and divided by n to obtain a weight matrix W (W) for each characteristic amount of voltage sagi)1×nThe calculation formula is
Figure BDA0001896858890000183
Through the above steps, the weights of the characteristic quantities of the voltage sag are 0.5555, 0.2595, 0.1161 and 0.0542, respectively.
B5, judging the comprehensive severity of the voltage sag of the node.
Combining the weight matrix W with the incidence matrix K, the evaluation result can be obtained as
P＝WK
The level corresponding to the maximum value in the matrix P is the level to which the object to be estimated belongs, and for the present invention, the level is the severity level of a single sag event.
And then determining the comprehensive severity of the voltage sag of the node. Assuming that the total number of sag events of a node is N, the number of sag events at each level is NⅠ、NⅡ、NⅢ、NⅣAnd NⅤAnd the comprehensive severity of the node is a comprehensive result of the times, and the final result is obtained by a weighted summation mode.
Let NⅠ、NⅡ、NⅢ、NⅣ、NⅤThe weights of (A) are respectively muⅠ、μⅡ、μⅢ、μⅣ、μⅤThe following three points should be considered when assigning the right: 1) when N is presentⅠAnd NⅤ、NⅡAnd NⅣWhen they are respectively equal, the overall severity should be neutral (grade III), that is, there is a complementary relationship between them, so that they should be mutually opposite numbers when giving weights; 2) level III is the only intermediate level, so NⅢThe weight of (2) cannot influence the deviation of the final result, so that the weight can be only given as 0; 3) and ensuring that the interval of each final grade judgment range is the same in size (except for the grade I and the grade V because the weight values of the grade I and the grade V are the upper limit value or the lower limit value), namely ensuring that the weight values are in an arithmetic progression. Taking mu in consideration of the three pointsⅠ、μⅡ、μⅢ、μⅣ、μⅤThe values of (A) are 1, 0.5, 0, -0.5, -1, respectively. Then according to
Figure BDA0001896858890000191
To which weight value, determines the overall level of severity of the node voltage sag, i.e., by S-muiI corresponding to the minimum value of I, II, III, IV and V is taken as the serious voltage sag of the nodeAnd obtaining the judgment relation of the node voltage sag severity comprehensive grade level according to the judgment result of the degree comprehensive grade level as follows:
Figure BDA0001896858890000192
the technical effects of the present invention will be described below by way of a specific effect experimental example.
Selecting a certain node from the power quality monitoring system in a certain area between 2017 and 2018 in the period of 10 months as a research object, wherein 9 voltage sag events occur to the node in the period, and each characteristic quantity parameter of the 9 voltage sag events is shown in table 3. The sag severity level evaluations were performed using data numbered 4 and 6 as examples. The results of normalizing and quantifying the monitoring data for numbers 4 and 6 are shown in table 4.
TABLE 3 Voltage sag monitoring data
Figure BDA0001896858890000201
Table 4 normalization quantization result of voltage sag monitoring data
Figure BDA0001896858890000202
From Table 4, two models of the object to be estimated can be established, respectively
Figure BDA0001896858890000203
The classification interval of Table 3 is divided into basis to form classical domains, which are respectively
Figure BDA0001896858890000204
And (3) combining the section domain of the voltage sag to obtain a correlation function value and form a correlation matrix as follows:
Figure BDA0001896858890000211
Figure BDA0001896858890000212
and combining the weight coefficients of the characteristic quantities to obtain a final evaluation matrix as follows:
P1＝W·K1＝[-0.347 -0.151 0.038 -0.431 -0.586]
P2＝W·K2＝[-0.310 0.188 -0.328 -0.488 -0.656]
the severity level of the sag events of numbers 4 and 6 are level iii and level ii, respectively, and the severity levels of other numbers of sag events can be obtained in the same manner. Counting the evaluation results of the 9 sag events, wherein the frequency of the grade II is 5, the frequency of the grade III and V is 2, and the frequency of the grade I and IV is 0, then
Figure BDA0001896858890000213
The voltage sag severity of this node is therefore class iii.
Through the above description, the basic functions of the method for describing and evaluating the node voltage sag tolerance characteristics are explained. According to the description method and the evaluation method for the node voltage sag tolerance characteristics, the diversity and the complexity of node access sensitive loads are fully considered, the VT plane is divided into 5 regions with different tolerance capacities according to the tolerance curves of 4 typical sensitive devices, the tolerance capacity of the node to the voltage sag can be reflected more intuitively, and the defects of the traditional curve in the aspect of describing the node sag tolerance capacity are overcome; a voltage sag evaluation model is established by adopting an extensional theory, four characteristic quantities of the voltage sag are comprehensively considered, and the voltage sag is more comprehensively evaluated, so that the evaluation result is more accurate and reasonable.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
In light of the foregoing description of the preferred embodiments according to the present application, it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims (6)

1. A method for describing and evaluating the voltage sag tolerance characteristics of a node is characterized by comprising the following steps:
s1: obtaining a sag amplitude v in a voltage sag event1Duration v of time2Starting point v3And phase jump v4；
S2: to V1、V2、V3And V4Performing dimensionless treatment to obtain V values1’、V2’、V3' and V4’，
Figure FDA0002941524280000011
VimaxThe maximum value of the value ranges of the corresponding sag amplitude, the duration, the starting point and the phase jump is represented, and i is an integer which is greater than or equal to 1 and less than or equal to 4;
s3: the association matrix K is established and,
Figure FDA0002941524280000012
kij＝v'i-a, when v'i∈(ai,j,ai,j+1]
Figure FDA0002941524280000013
When in use
Figure FDA0002941524280000014
j is an integer of 1 to 5 inclusive;
wherein, ai,j、ai,j+1The value ranges are set according to the severity and corresponding to the sag amplitude, the duration, the starting point and the phase jump after the dimensionless processing;
s4: according to the sag amplitude, the duration, the starting point and the weight matrix W of the phase jump, multiplying the weight matrix W by the incidence matrix K and evaluating the node voltage sag severity according to the result, namely:
Figure FDA0002941524280000015
rank represents the grade of the severity of the voltage sag, S is the estimated value of the voltage sag, and the severity of the voltage sag increases from grade I to grade V in grade level;
wherein, calculating P ═ W.K to obtain P ═ P1 p2 p3 p4 p5]Wherein the weight matrix W ═ 0.55550.25950.11610.0542]；
Voltage sag severity evaluation value: S-MAX (P)1 P2 P3 P4 P5)。
2. The method according to claim 1, wherein the node voltage sag tolerance characteristic is described and evaluated,
a1,1＝1，a1,2＝0.844，a1,3＝0.611，a1,4＝0.389，a1,5＝0.167，a1,6＝0，
a2,1＝1，a2,2＝0.994，a2,3＝0.760，a2,4＝0.525，a2,5＝0.290，a2,6＝0，
a3,1＝1，a3,2＝0.556，a3,3＝0.444，a3,4＝0.222，a3,5＝0.111，a3,6＝0，
a4,1＝1，a4,2＝0.556，a4,3＝0.444，a4,4＝0.222，a4,5＝0.111，a4,6＝0。
3. the method of claim 1, wherein the calculation is performed if the voltage sag event is a global event and occurs multiple times
Figure FDA0002941524280000021
Wherein N is the number of voltage sag events, N1、n2、n4、n5The times that the node voltage sag severity comprehensive grade levels are respectively grade I, grade II, grade IV and grade V are used for evaluating the node voltage sag severity comprehensive grade levels of the whole event
Figure FDA0002941524280000022
The judgment criterion of (2) is the same as that of (S).
4. An apparatus for describing and evaluating voltage sag tolerance characteristics of a node, comprising:
a data acquisition module: for obtaining sag amplitude V in voltage sag event1Duration V2Starting point V3And phase jump V4；
Dimensionless processing module, pair V1、V2、V3And V4Respectively obtained values V subjected to dimensionless processing1’、V2’、V3' and V4’，
Figure FDA0002941524280000023
VimaxThe maximum value of the value ranges of the corresponding sag amplitude, the duration, the starting point and the phase jump is represented, and i is an integer which is greater than or equal to 1 and less than or equal to 4;
an incidence matrix establishing module for establishing an incidence matrix K,
Figure FDA0002941524280000024
kij＝v'i-a, when v'i∈(ai,j,ai,j+1]
Figure FDA0002941524280000031
When in use
Figure FDA0002941524280000032
j is an integer of 1 to 5 inclusive;
wherein, ai,j、ai,j+1The value ranges are set according to the severity and corresponding to the sag amplitude, the duration, the starting point and the phase jump after the dimensionless processing;
an evaluation module: according to the sag amplitude, the duration, the starting point and the weight matrix W of the phase jump, multiplying the weight matrix W by the incidence matrix K and evaluating the node voltage sag severity according to the result, namely:
Figure FDA0002941524280000033
rank represents the grade of the severity of the voltage sag, S is the estimated value of the voltage sag, and the severity of the voltage sag increases from grade I to grade V in grade level;
wherein, calculating P ═ W.K to obtain P ═ P1 p2 p3 p4 p5]Wherein the weight matrix W ═ 0.55550.25950.11610.0542]；
Voltage sag severity evaluation value：S＝MAX(P1 P2 P3 P4 P5)。
5. The apparatus according to claim 4, wherein the correlation matrix building module is configured to describe and evaluate voltage sag tolerance characteristics of the nodes
a1,1＝1，a1,2＝0.844，a1,3＝0.611，a1,4＝0.389，a1,5＝0.167，a1,6＝0，
a2,1＝1，a2,2＝0.994，a2,3＝0.760，a2,4＝0.525，a2,5＝0.290，a2,6＝0，
a3,1＝1，a3,2＝0.556，a3,3＝0.444，a3,4＝0.222，a3,5＝0.111，a3,6＝0，
a4,1＝1，a4,2＝0.556，a4,3＝0.444，a4,4＝0.222，a4,5＝0.111，a4,6＝0。
6. The apparatus according to claim 4, further comprising a global event evaluation module for evaluating if the voltage sag event is a global event, and calculating
Figure FDA0002941524280000041
Wherein N is the number of voltage sag events, N1、n2、n4、n5The times that the node voltage sag severity comprehensive grade levels are respectively grade I, grade II, grade IV and grade V are used for evaluating the node voltage sag severity comprehensive grade levels of the whole event
Figure FDA0002941524280000042
The judgment standard of (1) and the judgment standard of (S)Quasi-identical.
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