CN103777096B - Based on how to drop threshold value and persistent period sensitive equipment immunocompetence appraisal procedure temporarily - Google Patents

Abstract

A kind of based on how to drop threshold value and persistent period sensitive equipment immunocompetence appraisal procedure temporarily, belong to power quality analysis technical field.To drop temporarily recorder data carry out virtual value calculate RMS waveform is dropped temporarily, ask and drop middle voltage temporarily less than or equal to the tolerant voltage magnitude U of equipment_cTime T (U_c), and then form the sequence dropping threshold value and persistent period more than temporarily；Form certain website to drop Description Matrix temporarily, drop description table and drop description figure temporarily temporarily；Carry out the single accident that drops temporarily to assess and sensitive equipment voltage dip immunocompetence website evaluation；Voltage dip Severity is carried out based on the seriousness aggregative indicator MMDSI proposed.Advantage is in that, based on how dropping threshold value temporarily and voltage dip is described by the persistent period, and and then the novel sensitive equipment voltage dip immunocompetence appraisal procedure that proposes can solve traditional method excessively assess, coarse problem, the order of severity of reasonable assessment voltage dip.

Description

Based on how to drop threshold value and persistent period sensitive equipment immunocompetence appraisal procedure temporarily

Technical field

The invention belongs to power quality analysis technical field, particularly relate to a kind of based on many sensitive equipment immunocompetence appraisal procedures dropping threshold value and persistent period temporarily.

Background technology

Voltage dip refers to the quality of power supply event owing to declining suddenly in the rms voltage short time that the reasons such as short-circuit fault of power system, large-size machine startup, transformer excitation flow cause.

The evaluation work of voltage dip processes mainly by electric energy quality monitoring system drops recorder data temporarily, obtains index of correlation value to describe individual event, website and system voltage and drops the order of severity temporarily and to electrical equipment influence degree.The size that sensitive equipment is affected by voltage dip, referring to the sensitive equipment immunocompetence size to voltage dip from sensitive equipment angle, its evaluation work is mainly based upon the voltage-tolerance curve of sensitive equipment and drops correlated characteristic temporarily with index to judge whether sensitive equipment can be affected, draw the affected frequency in conjunction with single event, the website of dropping temporarily.

In traditional sensitive equipment voltage dip immunocompetence appraisal procedure, voltage dip temporary range of decrease value and persistent period describe.Temporary range of decrease value refers to that the minimum voltage amplitude dropped temporarily in process accounts for the percentage ratio of nominal voltage, and the persistent period refers to drops in process voltage magnitude temporarily lower than the time dropping threshold value temporarily.Traditional appraisal procedure assumes that temporary range of decrease value change waveform is square wave, and actually voltage dip is really not so, because the initial period of voltage dip and Restoration stage are not instantaneous completing, what especially direct current generator startup and transformer excitation flow caused drops temporarily, and its Restoration stage persistent period can be very long.In other words, Traditional measurements method is coarse or even is inapplicable.Different sensitive equipment voltage immunocompetences is different, even same kind of sensitive equipment because of its manufacturer, hardware, control method difference, its voltage immunocompetence also differs, and voltage dip describes method, and to be not coupled to concrete sensitive equipment characteristic be also the inapplicable major reason of Traditional measurements method.

Summary of the invention

It is an object of the invention to provide a kind of based on how to drop threshold value and persistent period sensitive equipment immunocompetence appraisal procedure temporarily, bonding apparatus voltage-tolerance curve proposes a kind of based on many novel description methods of voltage dip dropping threshold value and persistent period temporarily, it is intended to apply in the assessment of equipment immunocompetence, to solve traditional method and excessively assess, coarse problem.In website evaluation method, it is proposed that the concept of description figure drops in website temporarily, and proposes the order of severity aggregative indicator based on the novel description of voltage dip, can the order of severity of reasonable assessment voltage dip.Specifically comprise the following steps that

Step 1: to drop temporarily recorder data carry out root-mean-square value calculate RMS waveform is dropped temporarily.Ask and drop middle voltage temporarily less than or equal to the tolerant voltage magnitude U of equipment_cTime T (U_c).And then being formed the sequence T (0.9) of threshold value and persistent period, T (0.9-h), T (0.9-2h) drop more than one temporarily ... T (0.1) wherein T is the time, and unit is ms.

Step 2: in certain month, certain season or certain year n individual arbitrary event 1≤i≤n that drops temporarily dropping in event temporarily monitored for certain website, adopt T_i(0.9)、T_i(0.9-h)、T_i(0.9-2h)……T_i(0.1) it is described, is formed and drop Description Matrix temporarily, drop description table and drop description figure temporarily temporarily.

Step 3: voltage dip Severity: adopt the website that step 2 produces to drop description figure temporarily, in conjunction with voltage dip severity index, drops the seriousness aggregative indicator MMDSI of description temporarily based on novel voltage, and the order of severity of assessment voltage dip includes:

(1) single event evaluation drops temporarily.Adopt the sequence that step 1 produces, in conjunction with sensitive equipment voltage-tolerance curve bound form or mean value formation, assess sensitive equipment voltage dip immunocompetence.

(2) sensitive equipment voltage dip immunocompetence website evaluation.Adopt the website that step 2 produces to drop description figure temporarily, in conjunction with sensitive equipment voltage-tolerance curve bound form or mean value formation, assess sensitive equipment voltage dip immunocompetence.

(3) voltage dip Severity.Adopt the website that step 2 produces to drop description figure temporarily, in conjunction with voltage dip severity index, drop the seriousness aggregative indicator MMDSI of description, the order of severity of assessment voltage dip temporarily based on novel voltage.

Technical scheme flow chart such as Fig. 1.

Step 1 is asked and drops middle voltage temporarily less than or equal to U_cTime T (U_c) process be:

Drop s temporarily and can be described as the voltage function about the time: U=s (t) or t=s^-1(U).For dropping the free voltage U in process temporarily_cT=s can be described as^-1(U), two can be tried to achieve according to RMS Wave data and solve t_c1, t_c2, wherein U is voltage, for perunit value.

Definition: T (U_c)=| t_c1-t_c2|, wherein 0.1≤U_c≤0.9。T(U_c) refer to and drop middle voltage temporarily less than or equal to U_cTime.

The process obtaining many sequences dropping threshold value and persistent period temporarily in step 1 is:

Owing to the immune voltage magnitude in the voltage-tolerance curve of equipment is generally accurate to arithmetic point the 2nd, the desirable 0.01-0.05p.u. of voltage spaces h.Utilize T (U_c) definition can in the hope of how to drop the sequence T (0.9) of threshold value and persistent period, T (0.9-h), T (0.9-2h) temporarily ... T (0.1).

Dropping Description Matrix forming process in step 2 temporarily is:

Dropping event temporarily for the n monitored in certain website month, certain season or certain year, utilize the many sequence computational methods dropping threshold value and persistent period temporarily in step 1, what website was monitored arbitrary drops event s temporarily_i(1≤i≤n), can be described as T_i(0.9)、T_i(0.9-h)、T_i(0.9-2h)……T_i(0.1), for more intuitive expression, can forming one and drop Description Matrix temporarily, row represent temporary descending chain, and row represents a certain all descriptions dropping event temporarily:

$T(i,j)=\left[\begin{array}{ccccccc}{T}_1\left(0.9\right)& T_1(0.9-h)& T_1(0.9-2h)& \mathrm{...}& T_1(0.9-jh)& \mathrm{...}& T_1\left(0.1\right)\\ T_2\left(0.9\right)& T_2(0.9-h)& T_2(0.9-2h)& \mathrm{...}& T_2(0.9-jh)& \mathrm{...}& T_2\left(0.1\right)\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ T_i\left(0.9\right)& T_i(0.9-h)& T_i(0.9-2h)& \mathrm{...}& T_i(0.9-jh)& & T_i\left(0.1\right)\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ T_n\left(0.9\right)& T_n(0.9-h)& T_n(0.9-2h)& \mathrm{...}& T_n(0.9-jh)& \mathrm{...}& T_n\left(0.1\right)\end{array}\right]$

Dropping description table forming process in step 2 temporarily is:

What formed in statistic procedure 2 drops in Description Matrix each threshold voltage persistent period temporarily be more than or equal to the event that drops the temporarily number of certain persistent period, as the element that form unit is corresponding, as shown in the table:

Dropping description figure forming method in step 2 temporarily is:

Being depicted as one with the time for abscissa by dropping every a line in description table temporarily, unity element is the curve of vertical coordinate, all collection of curves is formed under the same coordinate system and drops description figure temporarily.

In step 3, the single case evaluating method that drops temporarily is:

When sensitive equipment voltage-tolerance curve adopts mean value formation such as Fig. 2, for this equipment, when voltage is lower than the tolerant voltage magnitude U of equipment_cAnd lower than U_cPersistent period is more than the duration T of voltage disturbance_cTime, device fails；Otherwise, this equipment normal operation.Wherein U_cFor withstanding voltage meansigma methods；T_cFor persistent period meansigma methods.Dropping description temporarily according to novel voltage, appraisal procedure is as follows: if T is (U_c)≥T_c, then equipment fault；If T is (U_c) < T_c, then equipment is normal.

When sensitive equipment voltage-tolerance curve adopts bound form such as Fig. 3, if voltage is higher than U_maxAnd the persistent period is less than T_minTime, equipment is working properly；If voltage is lower than U_minAnd the persistent period is more than T_max, equipment fault；During other situations, equipment is in uncertain region, and namely likely normal operation is also possible to break down.Wherein U_maxFor upper voltage limit；U_minFor lower voltage limit；T_maxFor the maximum persistent period；T_minFor minimum duration.Dropping description temporarily according to novel voltage, appraisal procedure is as follows: if T is (U_max) < T_min, then equipment is normal；If T is (U_min)≥T_max, then equipment fault；If T is (U_max)≥T_minAnd T (U_min) < T_max, then equipment is in uncertain region.

In step 3, website evaluation is generally to be formed and describes website and drop index or the chart of information temporarily, in order to reflect the order of severity that website drops temporarily and the fault frequency etc. of the equipment powered thereof.

In step 3, sensitive equipment voltage dip immunocompetence website evaluation method is:

When evaluated sensitive equipment voltage-tolerance curve is known, when adopting mean value formation, when dropping immunocompetence website evaluation temporarily, find its voltage-tolerance curve flex point (U_avr,T_avr) at Fig. 5 website, the position in description figure drops temporarily, for instance D point, the then vertical coordinate that the fault frequency is D point correspondence that this equipment causes for a year because of voltage dip, it is set to y (D).

When evaluated sensitive equipment voltage-tolerance curve is unknown, adopts bound form, find its upper limit, lower limit curve flex point (U_max,T_min)、(U_min,T_max) at Fig. 5 website, the position in description figure drops temporarily, for instance A, B point.The quantity that drops temporarily being in normal region is n-y (A), fault zone quantity is y (B), uncertain region is y (A)-y (B), then this equipment 1 year because of the fault frequency that voltage dip causes be (y (B), y (A)).

In step 3, persistent period severity index (DSI), temporary range of decrease value severity index (MSI) and seriousness aggregative indicator (MDSI) can be described as:

$\begin{array}{cc}DSI\left(T\right)=\left\{\begin{array}{cc}0,& T<T_{\min }\\ (T-T_{\min })\&times;\left(\frac{100}{T_{\max }-T_{\min }}\right),& T_{\min }\&le;T\&le;T_{\max }\\ 100,& T>T_{\max }\end{array}\right.& MSI\left(U\right)=\left\{\begin{array}{cc}0,& U>U_{\max }\\ (U_{\max }-U)\&times;\left(\frac{100}{U_{\max }-U_{\min }}\right),& U_{\min }\&le;U\&le;U_{\max }\\ 100,& U>U_{\min }\end{array}\right.\end{array}$

$MDSI(U,T)=\frac{MSI\left(U\right)\&times;DSI\left(T\right)}{100}$

The severity index production method dropping description in step 3 based on novel voltage temporarily is:

In conjunction with the concept of severity index, can obtain dropping temporarily the seriousness aggregative indicator MMDSI of description based on novel voltage:

MMDSI=max{MDSI (0.9, T (0.9)), MDSI (0.9-h, T (0.9-h)) ... MDSI (0.1, T (0.1)) }.

If MMDSI=0, then can obtain T (U_max) < T_min, equipment is normal.If MMDSI=100, then can obtain: T (U_min)≥T_max, then equipment fault.If between MMDSI value 0-100, then can obtain T (U_max)≥T_minAnd T (U_min) < T_max, equipment is in uncertain region, and MMDSI is more big, drops closer to voltage-tolerance curve lower limit temporarily, drops more serious temporarily.

It is an advantage of the current invention that, based on how dropping threshold value temporarily and voltage dip is described by the persistent period, and and then the novel sensitive equipment voltage dip immunocompetence appraisal procedure that proposes can solve traditional method excessively assess, coarse problem, the order of severity of reasonable assessment voltage dip.

Accompanying drawing explanation

Fig. 1 is the technology of the present invention flow chart

Fig. 2 is sensitive equipment voltage-tolerance curve

Fig. 3 is sensitive equipment voltage-tolerance curve bound form and mean value formation.

Fig. 4 is that certain website voltage dip describes table data.

Fig. 5 is certain website voltage dip description figure.

Fig. 6 is four quasi-representative sensitive equipment voltage-tolerance curve data.

Fig. 7 is the assessment result adopting voltage-tolerance curve mean value formation.

Fig. 8 is the assessment result adopting voltage-tolerance curve bound form.

Fig. 9 is voltage dip severity index MDSI and MMDSI of PC.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with a certain electric energy quality monitoring system voltage dip recorder data of China, for the present invention propose the website evaluation method for sensitive equipment voltage dip immunocompetence, to can programming in logic device (PLC), speed adjustable device (ASD), AC relay (ACRelay), personal computer (PC) 4 quasi-representative sensitive equipment be estimated.It is emphasized that the description below is merely exemplary, rather than in order to limit the scope of the present invention and application thereof.

Step 1: to drop temporarily recorder data carry out root-mean-square value calculate RMS waveform is dropped temporarily.

Free voltage U in process drops temporarily_cT=s can be described as^-1(U), two can be tried to achieve according to RMS Wave data and solve t_c1, t_c2,.Then T (U_c)=| t_c1-t_c2| wherein 0.1≤U_c≤0.9。T(U_c) refer to and drop middle voltage temporarily less than or equal to U_cTime.

Step 2: what certain moon (certain season, certain year) n monitored for certain website dropped in event temporarily arbitrary drops event 1≤i≤n temporarily, calculates T respectively_i(0.9)、T_i(0.9-h)、T_i(0.9-2h)……T_i(0.1), h takes 0.05, obtains the multiple voltage dip of website and is described as many sequence T dropping threshold value and persistent period temporarily_i(0.9)、T_i(0.9-h)、T_i(0.9-2h)……T_i(0.1), now h takes 0.05.And then statistics temporarily drop description sequence in each threshold voltage persistent period obtain Fig. 4 be more than or equal to the event that drops the temporarily number of certain persistent period.

Being depicted as one with the time for abscissa by dropping every a line in description table temporarily, unity element is the curve of vertical coordinate, all collection of curves is formed under the same coordinate system and drops description figure such as Fig. 5 temporarily.

Step 3:(1) single event evaluation drops temporarily.Adopt the sequence that step 1 produces, in conjunction with sensitive equipment voltage-tolerance curve bound form or mean value formation, assess sensitive equipment voltage dip immunocompetence.

In conjunction with voltage-tolerance curve flex point data such as Fig. 6 of evaluated equipment, adopt mean value formation, find its voltage-tolerance curve flex point (U_avr,T_avr) at Fig. 5 website, the position in description figure drops temporarily, for instance D point, the then vertical coordinate that the fault frequency is D point correspondence that this equipment causes for a year because of voltage dip, it is set to y (D).

Analyzing contrast adopts novel voltage to drop the assessment result describing the fault frequency that the voltage dip with traditional description causes temporarily, as shown in Figure 7.

As seen from Figure 7,4 kind equipment voltage-tolerance curve mean value formation, the fault frequency that traditional method draws adopts method acquired results big than the present invention.Traditional method obtain fault rate method adopted than the present invention acquired results of four kind equipments respectively high by 9.7%, 10.9%, 9.5% and 15.2%.The shortcoming that the previously described traditional method of the contrast verification of assessment result is excessively assessed, and adopt the inventive method to carry out the feasibility of equipment voltage dip immunocompetence assessment.

(2) sensitive equipment voltage dip immunocompetence website evaluation.The website that step 2 produces drops description figure temporarily and assesses sensitive equipment voltage dip immunocompetence in conjunction with sensitive equipment voltage-tolerance curve bound form or mean value formation.

Adopt voltage-tolerance curve upper and lower limit shape form, find its upper limit, lower limit curve flex point (U_max,T_min)、(U_min,T_max) at Fig. 5 website, the position in description figure drops temporarily, for instance A, B point.The quantity that drops temporarily being in normal region is n-y (A), fault zone quantity is y (B), uncertain region is y (A)-y (B), then this equipment 1 year because of the fault frequency that voltage dip causes be (y (B), y (A)).

Analyzing contrast adopts novel voltage to drop the assessment result describing the fault frequency that the voltage dip with traditional description causes temporarily, as shown in Figure 8.

As seen from Figure 8,4 kind equipment voltage-tolerance curve bound forms, the fault frequency, interval that traditional method draws all adopt method acquired results big than the present invention.The shortcoming that the previously described traditional method of the contrast verification of assessment result is excessively assessed, and adopt the inventive method to carry out the feasibility of equipment voltage dip immunocompetence assessment.

(3) voltage dip Severity.Without loss of generality, herein for PC.Three below formula is utilized to calculate MDSI (0.9, T (0.9)), MDSI (0.9-h, T (0.9-h)) ... MDSI (0.1, T (0.1)).

$\begin{array}{cc}DSI\left(T\right)=\left\{\begin{array}{cc}0,& T<T_{\min }\\ (T-T_{\min })\&times;\left(\frac{100}{T_{\max }-T_{\min }}\right),& T_{\min }\&le;T\&le;T_{\max }\\ 100,& T>T_{\max }\end{array}\right.& MSI\left(U\right)=\left\{\begin{array}{cc}0,& U>U_{\max }\\ (U_{\max }-U)\&times;\left(\frac{100}{U_{\max }-U_{\min }}\right),& U_{\min }\&le;U\&le;U_{\max }\\ 100,& U>U_{\min }\end{array}\right.\end{array}$

$MDSI(U,T)=\frac{MSI\left(U\right)\&times;DSI\left(T\right)}{100}$

Can obtain dropping temporarily the seriousness aggregative indicator MMDSI of description based on novel voltage:

MMDSI=max{MDSI (0.9, T (0.9)), MDSI (0.9-h, T (0.9-h)) ... MDSI (0.1, T (0.1)) }.

If MMDSI=0, then can obtain T (U_max) < T_min, equipment is normal.If MMDSI=100, then can obtain: T (U_min)≥T_max, then equipment fault.If between MMDSI value 0-100, then can obtain T (U_max)≥T_minAnd T (U_min) < T_max, equipment is in uncertain region, and MMDSI is more big, drops closer to voltage-tolerance curve lower limit temporarily, drops more serious temporarily.

Analyzing contrast adopts novel voltage to drop the assessment result of the seriousness aggregative indicator (MMDSI) describing seriousness aggregative indicator (MMDSI) traditional description temporarily, as shown in Figure 9.

As shown in Figure 9, dropping temporarily for arbitrary, its MMDSI value is both less than or equal to MDSI value；Adopt some assessment of MDSI to make equipment be in dropping temporarily of malfunction, when adopting MMDSI assessment, equipment fault can't be made, and be in the range of indeterminacy, even normal region；Some assessment of MDSI is adopted to make equipment be in dropping temporarily of uncertain region, when adopting MMDSI assessment, its order of severity is generally little, even for 0, namely being in normal region, this is mainly determined by the non-rectangle degree dropped temporarily, and non-rectangle degree is more high, adopting traditional method excessively to assess degree more high, the difference of MDSI and MMDSI is also more big.Some with MDSI assessment makes equipment be in dropping temporarily of normal region, when adopting MMDSI assessment, is then certainly in normal region.There is the shortcoming of excessively assessment in the voltage dip severity MDSI namely adopting traditional method, and adopt the severity MMDSI of the novel description of voltage dip can well solve this problem when assessing non-rectangle and dropping temporarily.

Above in association with accompanying drawing embodiment, the present invention being described in detail, the present invention can be made many variations example by those skilled in the art according to the above description.Thus, some details in embodiment should not constitute limitation of the invention, the present invention by the scope that defines using appended claims as protection scope of the present invention.

Claims (4)

1. one kind based on how to drop threshold value and persistent period sensitive equipment immunocompetence appraisal procedure temporarily, it is characterised in that comprises the following steps:

Step 1: to drop temporarily recorder data carry out root-mean-square value calculate RMS waveform is dropped temporarily；Ask and drop middle voltage temporarily less than or equal to the tolerant voltage U of equipment_cTime T (U_c)；And then being formed the sequence T (0.9) of threshold value and persistent period, T (0.9-h), T (0.9-2h) drop more than one temporarily ... T (0.1), wherein T is the time, unit is ms, h is voltage spaces, takes 0.01 0.05p.u.；

Step 2: monitor for certain website certain month, drop in certain season or certain year n in event temporarily arbitrary event s drops temporarily_i, wherein 1≤i≤n, adopt T_i(0.9)、T_i(0.9-h)、T_i(0.9-2h)……T_i(0.1) it is described, is formed and drop Description Matrix temporarily, drop description table and drop description figure temporarily temporarily, wherein 0.9,0.9-h, 0.9-2h ... 0.1 is voltage threshold；

Step 3: voltage dip Severity: adopt the website that step 2 produces to drop description figure temporarily, in conjunction with voltage dip severity index, it is proposed to drop the seriousness aggregative indicator MMDSI of description temporarily based on novel voltage, the order of severity of assessment voltage dip includes:

Single drop event evaluation temporarily: adopt the sequence that step 1 produces, in conjunction with sensitive equipment voltage-tolerance curve bound form or mean value formation, assess sensitive equipment voltage dip immunocompetence；

Sensitive equipment voltage dip immunocompetence website evaluation: adopt the website that step 2 produces to drop description figure temporarily, in conjunction with sensitive equipment voltage-tolerance curve bound form or mean value formation, assesses sensitive equipment voltage dip immunocompetence；

Voltage dip Severity: adopt the website that step 2 produces to drop description figure temporarily, in conjunction with voltage dip severity index, drops the seriousness aggregative indicator MMDSI of description, the order of severity of assessment voltage dip temporarily based on novel voltage；

Propose to drop temporarily the seriousness aggregative indicator MMDSI of description based on novel voltage:

MMDSI=max{MDSI (0.9, T (0.9)), MDSI (0.9-h, T (0.9-h)) ... MDSI (0.1, T (0.1)) }；

Wherein,

$\begin{array}{cc}DSI\left(T\right)=\left\{\begin{array}{cc}0,& T<T_{\min }\\ (T-T_{\min })\&times;\left(\frac{100}{T_{\max }-T_{\min }}\right),& T_{\min }\&le;T\&le;T_{\max }\\ 100,& T>T_{\max }\end{array}\right.& MSI\left(U\right)=\left\{\begin{array}{cc}0,& U>U_{\max }\\ (U_{\max }-U)\&times;\left(\frac{100}{U_{\max }-U_{\min }}\right),& U_{\min }\&le;U\&le;U_{\max }\\ 100,& U<U_{\min }\end{array}\right.\end{array}$

Utilize the order of severity that the seriousness aggregative indicator MMDSI reflecting voltage dropping description based on novel voltage temporarily drops temporarily: work as MMDSI=0, then obtain T (U_max)<T_min, equipment is normal；Work as MMDSI=100, then obtain T (U_min)≥T_max, then equipment fault；Between MMDSI value 0-100, then obtain T (U_max)≥T_minAnd T (U_min)<T_max, equipment is in uncertain region, and MMDSI is more big, drops closer to voltage-tolerance curve lower limit temporarily, drops more serious temporarily.

2. method according to claim 1, it is characterized in that, in described step 1, form the sequence dropping threshold value and persistent period more than temporarily: T (0.9), T (0.9-h), T (0.9-2h) ... T (0.1), wherein T is the time, and unit is ms；H is voltage spaces, takes 0.01-0.05p.u.；Adopt definition T (U_c)=| t_c1-t_c2|, wherein 0.1≤U_c≤0.9,U_cFor voltage, for perunit value；Certain drops event s temporarily and is described as one about the function of time: U=s (t) or t=s^-1(U), for dropping the free voltage U in process temporarily_cIt is described as t=s^-1(U_c), try to achieve two according to RMS Wave data and solve t_c1, t_c2, T (U_c) refer to and drop middle voltage temporarily less than or equal to U_cTime.

3. method according to claim 1, it is characterized in that, in step 2, form certain website and drop Description Matrix temporarily: event drops in certain moon, certain season or certain year n temporarily that monitor for certain website, utilize the many sequence computational methods dropping threshold value and persistent period temporarily in step 1, drop event s temporarily to arbitrary_i, 1≤i≤n, it is described as T_i(0.9)、T_i(0.9-h)、T_i(0.9-2h)……T_i(0.1), representing intuitively, forming one and drop Description Matrix temporarily, row represent temporary descending chain, and row represents a certain all descriptions dropped temporarily:

$T(i,j)=\left[\begin{array}{ccccccc}{T}_1\left(0.9\right)& T_1(0.9-h)& T_1(0.9-2h)& \mathrm{...}& T_1(0.9-jh)& \mathrm{...}& T_1\left(0.1\right)\\ T_2\left(0.9\right)& T_2(0.9-h)& T_2(0.9-2h)& \mathrm{...}& T_2(0.9-jh)& \mathrm{...}& T_2\left(0.1\right)\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ T_i\left(0.9\right)& T_i(0.9-h)& T_i(0.9-2h)& \mathrm{...}& T_i(0.9-jh)& \mathrm{...}& T_i\left(0.1\right)\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ .& .& .& & .& & .\\ T_n\left(0.9\right)& T_n(0.9-h)& T_n(0.9-2h)& \mathrm{...}& T_n(0.9-jh)& \mathrm{...}& T_n\left(0.1\right)\end{array}\right].$

4. method according to claim 1, it is characterised in that in step 2, forms certain website and drops description table temporarily and drop description figure temporarily；Description table forming method drops temporarily as follows: title behavioral duration, title is classified as and drops threshold value temporarily, what formed in statistic procedure 2 drops in Description Matrix each voltage threshold persistent period temporarily be more than or equal to the event that drops the temporarily number of certain persistent period, as the element that form unit is corresponding；Being depicted as one with the time for abscissa by dropping every a line in description table temporarily, unity element is the curve of vertical coordinate, all collection of curves is formed under the same coordinate system and drops description figure temporarily.