CN103001235B - Method for evaluating risks of MOV (metal oxide varistor) of series capacitive compensator - Google Patents

Abstract

The invention discloses a method for evaluating risks of an MOV (metal oxide varistor) of a series capacitive compensator. The method includes the steps of (1) acquiring parameters including preventive trial data and electric monitoring data of the MOV of the series capacitive compensator; (2) establishing characteristic quantity including failure modes and probability of risk occurrence, establishing an incidence matrix about the probability of risk occurrence and failure modes, and establishing the risk evaluation for the MOV of the series capacitive compensator. Based on preventive trials, unbalanced current and historical data, the method can evaluate series compensation risks, simultaneously breaks through design and manufacture problem of international high-energy high-capacity MOVs, and improves operation reliability of the series compensation system.

Description

A kind of compensator with series capaci tance MOV methods of risk assessment

Technical field

The present invention relates to the series capacitor compensation technology field of ac transmission, particularly a kind of compensator with series capaci tance MOV methods of risk assessment.

Background technology

Along with the continuous growth of national economy and entire society are to the enhancing of energy demand, the new power transmission line corridor of planning that causes in short supply of land resource brings great difficulty simultaneously, and the utilance therefore improving existing power transmission line corridor solves current difficulty important effect.Its method has HVDC Light, raising line voltage distribution grade, multiple-loop line transmission of electricity construction, compensator with series capaci tance (string is mended) etc., but HVDC Light, raising line voltage distribution grade, multiple-loop line transmission of electricity construction can concentrate power transmission to large load center, but need transformation electric power line pole tower type or insulation coordination level, and compensator with series capaci tance only need install the utilance that power transmission line corridor can be improved in string benefit station additional, therefore comparatively other technologies, compensator with series capaci tance has obvious advantage.

The main purpose of series capacitance compensator be reduce transmission line from sending end to receiving end between total equivalent series resistance, its Main Function has: the impedance 1) changing system, 2) improve transmittability, power flowcontrol, reduce network loss, 3) Controlling vertex voltage, improves reactive balance, improves static voltage stability, 4) dynamic behaviour of electric power system is improved, damping system low frequency and sub-synchronous oscillation, 5) improve transient stability, 6) seal in inductance minimizing short circuit current.When string complement system breaks down, the MOV being connected in parallel on capacitor two ends heavily protects as first, and its voltage by capacitor short-circuit, and is limited in the residual voltage level of lightning arrester by its quick acting, reactor is sealed in system to suppress the first peak value of short circuit current simultaneously.During the system failure, short circuit current mainly flows through from MOV, and it must absorb huge short circuit energy within the quite short time, causes self-heating temperature to raise.The accident of current generation has: 1) during 3 days 15 March in 2008 16 points 54 seconds, 500kV horse hundred line B phase transient fault, after about 57.50ms, protection act tripping circuit B phase.After failure removal, about 1049ms switch overlaps, and circuit resumes operation, and this maximum fault current appears at fault and starts rear 31.88ms, current peak 8251A.B phase fault again after coincidence 241ms, after about 66.25ms, protection act tripping circuit three-phase; this maximum fault current appears at fault and starts rear 31.25ms; current peak 8103A, now horse hundred line string is mended B phase MOV and explode when second time fault damages, goes here and there benefit Permanent lockout.2) during 10 days 15 February in 2010 38 points, there is A, B phase-to phase fault (being called for short first time line fault) in sieve 500kV hundred I line, and route protection correct operation excision fault, reclosing is failure to actuate, and sieve 500kV hundred I line string mends three-phase bypass, does not heavily throw.Before tripping operation, sieve 500kV hundred I specific electric load is P:143.73MW, voltage 543.47kV, electric current 259.28A, through sieve 500kV hundred I line and string are mended the relevant secondary device in interval check without exception after, when 16,37 points of circuits and string are mended and are successively recovered normal operation; When 17 09 point, there is B, C phase-to phase fault (being called for short second time line fault) in sieve 500kV hundred I line, route protection correct operation excision fault, and fault simultaneously sieve 500kV hundred I line string is mended B phase MOV fault and burst damage, and string mends Permanent lockout.Sieve 500kV hundred I line load P:59.88MW at that time before second time fault trip, voltage 539.40kV, electric current 92.29A.3) 2010 03 month 27 days 21 time 25 points 18 seconds, the tripping operation of 500kV horse hundred line B, C alternate earth fault three-phase.Horse hundred specific electric load P:161.49MW, voltage 536kV, electric current 203.61A at that time.500kV horse hundred line string mends three-phase bypass, does not heavily throw, and goes up on the stage to check to find that B phase goes here and there the action of a benefit MOV pressure relief device, and MOV thoroughly damages, and string mends Permanent lockout.Therefore the safe and stable operation of MOV drastically influence the reliability of string complement system.

Mend the state analysis of MOV for string to have: based on the reference voltage under the insulation resistance of preventive trial, 1mA, the Leakage Current under 0.75 reference voltage; The unsymmetrical current of Control protection is mended based on string; Based on historical datas such as device manufacturing process level, familial defect, fault case, defect analysiss; In the world high energy Large Copacity MOV manufacture and design the core secrecy technology still belonging to each company; Simultaneously existing method to MOV risk assessment by preventive trial data, unsymmetrical current, historical data, manufacturing process etc. respectively by different professionals evaluate.Therefore based on existing monitoring means, carry out systematic string and mend MOV methods of risk assessment, to improving the string reliable rate of complement system and ensureing that the continual and steady energy resource supply of power transmission line corridor has great significance, facilitate the sustainable growth of national economy.

Summary of the invention

The object of the invention is to overcome existing carry out going here and there based on preventive trial, unsymmetrical current, historical summary respectively mend the one-sidedness that risk assessment exists, break through the barrier problem manufactured and designed of high energy Large Copacity MOV in the world simultaneously, improve the reliable rate of string complement system, a kind of compensator with series capaci tance MOV methods of risk assessment is provided.

For realizing above object, this invention takes following technical scheme: the methods of risk assessment of a kind of compensator with series capaci tance MOV, comprises the steps:

S1, parameter acquiring: the preventive trial data of compensator with series capaci tance MOV, the live monitoring data of compensator with series capaci tance MOV;

The preventive trial packet of described compensator with series capaci tance MOV is containing insulation resistance, absorptance and polarization index, DC reference voltage under 1mA, DC reference voltage under 4mA, leakage current under 0.75 times of DC reference voltage, the power frequency reference voltage under 1mA; Power frequency reference voltage under 4mA, current in resistance property;

The live monitoring data of described compensator with series capaci tance MOV comprise the running current of compensator with series capaci tance MOV, the unsymmetrical current of compensator with series capaci tance MOV, the working voltage of compensator with series capaci tance MOV, the force value of compensator with series capaci tance MOV, the body temperature of compensator with series capaci tance MOV, the ambient temperature of compensator with series capaci tance MOV, the surface filth of compensator with series capaci tance MOV;

S2, parameter acquiring according to compensator with series capaci tance MOV methods of risk assessment, set up the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, it comprises the coding of preventive trial data and live monitoring data, characterizing magnitudes, pilot project;

The characterizing magnitudes of compensator with series capaci tance MOV methods of risk assessment is formed vectorial D, the characteristic quantity sum of its size to be 1 × N, N be compensator with series capaci tance MOV methods of risk assessment,

First of vector D is classified as the value of pilot project insulation resistance, corresponding coding Y ₁; Second is classified as pilot project absorptance or polarization index value, corresponding coding Y ₂; 3rd is classified as the DC reference voltage value under pilot project 1mA, corresponding coding Y ₃; 4th is classified as the DC reference voltage value under pilot project 4mA, corresponding coding Y ₄; 5th is classified as leakage current values under pilot project 0.75 times of DC reference voltage, corresponding coding Y ₅; 6th is classified as the power frequency reference voltage value under pilot project 1mA, corresponding coding Y ₆; 7th is classified as the power frequency reference voltage value under pilot project 4mA, corresponding coding Y ₇; 8th is classified as pilot project current in resistance property value, corresponding coding Y ₈; The 9th running current value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₉; The tenth unsymmetrical current value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₁₀; The 11 working voltage value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₁₁; 12 force value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₁₂; The 13 body temperature value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₁₃; 14 ambient temperature value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₁₄; The 15 surface filth value being classified as pilot project compensator with series capaci tance MOV, corresponding coding Y ₁₅;

The fault mode of S3, compensator with series capaci tance MOV methods of risk assessment

According to the system composition function of compensator with series capaci tance MOV, establish for MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the fault mode of composite silicone rubber material umbrella cover unit, the fault mode of each unit comprises function code, fault mode code, failure-description simultaneously.

The fault mode of described MOV valve block unit comprises function code A1, and fault mode code is A1.1, and failure-description is the aging of MOV valve block or makes moist, and fault mode code is A1.2, and failure-description is puncturing of MOV valve block;

The fault mode of described aluminum annular-shaped conductive cushion block unit comprises function code A2, and fault mode code is A2.1, and failure-description is the loose contact of aluminum annular-shaped conductive cushion block unit, and fault mode code is A1.2, and failure-description is making moist of aluminum annular-shaped conductive cushion block unit;

The fault mode of described coolant unit comprises function code A3, and fault mode code is A3.1, and failure-description is coolant units age, and fault mode code is A3.2, and failure-description is that coolant cell temperature is too high;

The fault mode of described epoxy resins insulation cartridge unit comprises function code A4, fault mode code is A4.1, failure-description is the aging of epoxy resins insulation cartridge unit or makes moist, and fault mode code is A4.2, and failure-description is puncturing of epoxy resins insulation cartridge unit;

The fault mode of described composite silicone rubber material umbrella cover unit comprises function code A5, fault mode code is A5.1, failure-description is the aging of composite silicone rubber material umbrella cover unit or makes moist, and fault mode code is A5.2, and failure-description is puncturing of composite silicone rubber material umbrella cover unit; Fault mode code is A5.3, and failure-description is the filth of composite silicone rubber material umbrella cover unit;

S4, characteristic quantity according to compensator with series capaci tance MOV methods of risk assessment, set up the risk probability of happening of compensator with series capaci tance MOV methods of risk assessment, the demand value of each characteristic quantity is divided into higher limit and lower limit, adopt the calculating formula of risk probability of happening such as formula (1) and (2) respectively, and form risk probability of happening vector K, the characteristic quantity sum of its size to be 1 × N, N be compensator with series capaci tance MOV methods of risk assessment;

$P\left(Y_i\right)=\frac{Y_i^2}{Y_i^2+a^2}---\left(1\right)$

$P\left(Y_i\right)=\left\{\begin{array}{cc}0.5-0.5\sin \frac{\mathrm{\π}}{2b}(Y_i-b)& Y_i\≤2b\\ 0& Y_i>2b\end{array}\right.---\left(2\right)$

In formula, a represents that demand value is higher limit, and b represents that demand value is lower limit, Y _irepresent the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, span Y ₁: Y ₁₅;

It is that 500M, absorptance and polarization index are respectively 1.3 and 1.5 that the demand value of described each characteristic quantity is divided into higher limit and lower limit to comprise insulation resistance demand value, DC reference voltage under 1mA is 120kV, DC reference voltage under 4mA is 45kV, under 0.75 times of DC reference voltage, leakage current is 50 μ A, the power frequency reference voltage 30kV under 1mA; Power frequency reference voltage under 4mA is 145kV, current in resistance property is 15 μ A, the running current of compensator with series capaci tance MOV is 35 μ A, the unsymmetrical current 500 μ A of compensator with series capaci tance MOV, the working voltage of compensator with series capaci tance MOV is 550kV, the force value of compensator with series capaci tance MOV is 1.2MPa, the body temperature of compensator with series capaci tance MOV is 150 DEG C, the ambient temperature of compensator with series capaci tance MOV is 55 DEG C, and the surface filth of compensator with series capaci tance MOV is 0.25mg/cm ²;

S5, according to the risk probability of happening that the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment is set up, relation in conjunction with characteristic quantity and fault mode is associated matrix M, its size is B × N, B represents total classification size of fault mode, the total quantity of N representation feature amount, the element M of its incidence matrices M _ijcomputational methods such as formula (3);

$M_{\mathrm{ij}}=\frac{\underset{j}{\min }\underset{i}{\min }|D_j-D_i|+\mathrm{\ξ}\underset{j}{\max }\underset{i}{\max }|D_j-D_i|}{|D_j-D_i|+\mathrm{\ξ}\underset{j}{\max }\underset{i}{\max }|D_j-D_i|}---\left(3\right)$

D in formula _jand D _irepresent characteristic of correspondence amount under jth and i kind fault mode respectively, ξ is resolution ratio, and span is (0,1);

S6, set up the risk assessment of compensator with series capaci tance MOV methods of risk assessment

According to the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, risk probability of happening and fault mode incidence matrices, set up for MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the risk assessment of composite silicone rubber material umbrella cover unit, its computational methods are such as formula (4);

$A_j=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{M}_{j\×i}\·D_i*w\left(i\right)---\left(4\right)$

A in formula _jfor jth kind fault mode, N is the total quantity of characteristic quantity, and w (i) represents the weight of i characteristic quantity for j kind fault mode, and span is (0,1);

Formula (4) is utilized to calculate MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the risk assessment value of composite silicone rubber material umbrella cover unit, then the value-at-risk of maximum as compensator with series capaci tance MOV of getting each unit risk assessment value.

The present invention compared with prior art, tool has the following advantages: the string carrying out system based on preventive trial, unsymmetrical current, historical summary mends risk assessment, that breaks through high energy Large Copacity MOV in the world manufactures and designs problem simultaneously, improves the reliable rate of string complement system.

Accompanying drawing explanation

Fig. 1 is system flow schematic diagram of the present invention;

Fig. 2 is the parameter acquiring schematic diagram of compensator with series capaci tance MOV methods of risk assessment;

Fig. 3 is the systemic-function schematic diagram of compensator with series capaci tance MOV.

Embodiment

Below in conjunction with the drawings and specific embodiments, content of the present invention is described in further details.

Embodiment: refer to shown in Fig. 1, for further illustrating feature of the present invention, the present embodiment is calculated as follows by concrete example:

The parameter acquiring of compensator with series capaci tance MOV methods of risk assessment comprises the insulation resistance meter measuring insulation resistance, absorptance and polarization index; Measure the DC reference voltage under 1mA, the DC reference voltage under 4mA, the high voltage direct current generator of leakage current under 0.75 times of DC reference voltage; Measure the power frequency reference voltage under 1mA; Power frequency reference voltage under 4mA, the power frequency generator of current in resistance property; Measure the running current of compensator with series capaci tance MOV, the current transformer of the unsymmetrical current of compensator with series capaci tance MOV; Measure the voltage transformer of the working voltage of compensator with series capaci tance MOV, measure the Pressure gauge of the force value of compensator with series capaci tance MOV, measure the body temperature of compensator with series capaci tance MOV, the thermometer of the ambient temperature of compensator with series capaci tance MOV, measure the surface filth of compensator with series capaci tance MOV measuring instrument, be commercially available prod.The numerical megger ST2000 that the insulation resistance meter measuring insulation resistance, absorptance and polarization index adopts Su Te electric, measure the DC reference voltage under 1mA, the DC reference voltage under 4mA, under 0.75 times of DC reference voltage, the high voltage direct current generator of leakage current adopts Wuhan City Huatian Electric Power Automation Co., Ltd. model BPXZ-50/50/25, measure the power frequency reference voltage under 1mA, power frequency reference voltage under 4mA, the power frequency generator of current in resistance property adopts the YD intelligence power frequency withstand test device of Nan electricity Hua source, Wuhan Electric Applicance Co., Ltd, measure the running current of compensator with series capaci tance MOV, the current transformer of the unsymmetrical current of compensator with series capaci tance MOV adopts the model LVQBT-500 of Henan Pinggao Toshiba High Voltage Switchgear Co., Ltd., the voltage transformer measuring the working voltage of compensator with series capaci tance MOV adopts model 26-1E-7980111 of Henan Pinggao Toshiba High Voltage Switchgear Co., Ltd., the Pressure gauge measuring the force value of compensator with series capaci tance MOV adopts the HQ-SY-C precision digital Pressure gauge of red flag instrument, measure the body temperature of compensator with series capaci tance MOV, the thermometer of the ambient temperature of compensator with series capaci tance MOV adopts the DSC-DTSnK-XB of Dien instrument, the measuring instrument measuring the surface filth of compensator with series capaci tance MOV adopt Nan electricity Hua source, Wuhan Electric Applicance Co., Ltd NDYMD digital direct-reading type intelligence salt density test instrument.Method step is as follows:

1, the parameter acquiring of compensator with series capaci tance MOV methods of risk assessment: the numerical megger ST2000 electric by Su Te measures insulation resistance, absorptance and polarization index; The DC reference voltage under 1mA is measured, the DC reference voltage under 4mA, leakage current under 0.75 times of DC reference voltage by Wuhan City Huatian Electric Power Automation Co., Ltd. model BPXZ-50/50/25; By the power frequency reference voltage under YD intelligence power frequency withstand test measurement device 1mA, the power frequency reference voltage under 4mA, current in resistance property; The running current of compensator with series capaci tance MOV is measured, the unsymmetrical current of compensator with series capaci tance MOV by the model LVQBT-500 of Henan Pinggao Toshiba High Voltage Switchgear Co., Ltd.; The working voltage of compensator with series capaci tance MOV is measured by model 26-1E-7980111 of Henan Pinggao Toshiba High Voltage Switchgear Co., Ltd.; By the force value of the HQ-SY-C precision digital gauge measurement compensator with series capaci tance MOV of red flag instrument; The body temperature of compensator with series capaci tance MOV is measured, the ambient temperature of compensator with series capaci tance MOV by the DSC-DTSnK-XB of Dien instrument; By Nan electricity Hua source, Wuhan Electric Applicance Co., Ltd NDYMD digital direct-reading type intelligence salt density test instrument measure the surface filth of compensator with series capaci tance MOV.Its measurement result is as table 1;

Table 1: the parameter of compensator with series capaci tance MOV methods of risk assessment

2, compensator with series capaci tance MOV methods of risk assessment

1) characteristic quantity of compensator with series capaci tance MOV methods of risk assessment: according to the parameter acquiring of compensator with series capaci tance MOV methods of risk assessment, set up the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, and form the characterizing magnitudes vector D of compensator with series capaci tance MOV methods of risk assessment, its size is 1 × 15, and wherein the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment adds up to 15;

$D=\left[\begin{array}{c}15.6\\ 1.4\\ .\\ .\\ .\\ 0.18\end{array}\right]$

2) fault mode of compensator with series capaci tance MOV methods of risk assessment

According to the system composition function of compensator with series capaci tance MOV, establish for MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the fault mode of composite silicone rubber material umbrella cover unit, the fault mode of each unit comprises function code, fault mode code, failure-description composition simultaneously, and its fault mode result is as table 2;

Function code	Fault mode code	Failure-description
			A1	A1.1	MOV valve block aging or make moist
A1	A1.2	Puncturing of MOV valve block
			...	...	...
A5	A5.3	The filth of composite silicone rubber material umbrella cover unit

3) the risk probability of happening of compensator with series capaci tance MOV methods of risk assessment

According to the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, set up the risk probability of happening of compensator with series capaci tance MOV methods of risk assessment, therefore the demand value of each characteristic quantity is divided into higher limit and lower limit, adopt the calculating formula of risk probability of happening such as formula (1) and (2) respectively, and forming risk probability of happening vector K, its size is 1 × 15;

$D=\left[\begin{array}{c}0.13\\ 0.014\\ .\\ .\\ .\\ 0.78\end{array}\right]$

4) risk probability of happening and the fault mode incidence matrices of compensator with series capaci tance MOV methods of risk assessment is set up

According to the risk probability of happening that the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment is set up, formula (3) is utilized to be associated matrix M, its size is 15 × 15 (B × N), and row coefficient 15 represents total classification size of fault mode, the total quantity of row coefficient 15 representation feature amount

$M=\left[\begin{array}{cccc}0.31& 0.31& ...& 0\\ 0.29& 0.25& ...& 0\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ 0.11& 0.05& ...& 0.8\end{array}\right]$

5) risk assessment of compensator with series capaci tance MOV methods of risk assessment is set up

According to the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, risk probability of happening and fault mode incidence matrices, utilize formula (4) to set up and carry out MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the risk assessment of composite silicone rubber material umbrella cover unit;

$\left[\begin{array}{c}{A}_1\\ A_2\\ .\\ .\\ .\\ A_{15}\end{array}\right]=\left[\begin{array}{c}0.073\\ 0.039\\ .\\ .\\ .\\ 0.852\end{array}\right]$

Therefore can judge that the aging of MOV valve block or the value-at-risk of making moist are as 0.073 according to above-mentioned matrix, the value-at-risk that punctures of MOV valve block is 0.03, the value-at-risk of other fault modes, the maximum of each unit risk assessment value is 0.852 as the value-at-risk of compensator with series capaci tance MOV simultaneously.

Effect analysis: by the analysis of above-mentioned example, can judge that the aging of MOV valve block or the value-at-risk of making moist are 0.03 as the value-at-risk that punctures of 0.073, MOV valve block, the value-at-risk of compensator with series capaci tance MOV is 0.852 simultaneously.Therefore the string that the method carries out system based on preventive trial, unsymmetrical current, historical summary mends risk assessment, and that breaks through high energy Large Copacity MOV in the world manufactures and designs problem simultaneously, improves the reliable rate of string complement system.

The present embodiment applies to:

1, the risk assessment of 500kV ac transmission compensator with series capaci tance MOV;

2, the operation risk analysis of 110kV and above ac transmission compensator with series capaci tance MOV, repair based on condition of component, aid decision;

Above-listed detailed description is illustrating for possible embodiments of the present invention, and this embodiment is also not used to limit the scope of the claims of the present invention, and the equivalence that all the present invention of disengaging do is implemented or changed, and all should be contained in the scope of the claims of this case.

Claims (1)

1. a compensator with series capaci tance MOV methods of risk assessment, is characterized in that, comprises the steps:

S1, parameter acquiring: the preventive trial data of compensator with series capaci tance MOV, the live monitoring data of compensator with series capaci tance MOV;

S2, parameter acquiring according to compensator with series capaci tance MOV methods of risk assessment, set up the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, it comprises the coding of preventive trial data and live monitoring data, characterizing magnitudes, pilot project; The characterizing magnitudes of compensator with series capaci tance MOV methods of risk assessment is formed vectorial D, the characteristic quantity sum of its size to be 1 × N, N be compensator with series capaci tance MOV methods of risk assessment;

The fault mode of S3, compensator with series capaci tance MOV methods of risk assessment

According to the system composition function of compensator with series capaci tance MOV, establish for MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the fault mode of composite silicone rubber material umbrella cover unit, the fault mode of each unit comprises function code, fault mode code, failure-description simultaneously;

S4, characteristic quantity according to compensator with series capaci tance MOV methods of risk assessment, set up the risk probability of happening of compensator with series capaci tance MOV methods of risk assessment, the demand value of each characteristic quantity is divided into higher limit and lower limit, adopt the calculating formula of risk probability of happening such as formula (1) and (2) respectively, and form risk probability of happening vector K, the characteristic quantity sum of its size to be 1 × N, N be compensator with series capaci tance MOV methods of risk assessment;

$P\left(Y_i\right)=\frac{{Y_i}^2}{{Y_i}^2+a^2}---\left(1\right)$

$P\left(Y_i\right)=\left\{\begin{array}{cc}0.5-0.5\sin \frac{\mathrm{\π}}{2b}(Y_i-b)& Y_i\≤2b\\ 0& Y_i>2b\end{array}\right.---\left(2\right)$

In formula, a represents that demand value is higher limit, and b represents that demand value is lower limit, Y _irepresent i-th kind of characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, the span of i is the natural number of 1 to 15, wherein Y ₁for the value of pilot project insulation resistance; Y ₂for pilot project absorptance or polarization index value; Y ₃for the DC reference voltage value under pilot project 1mA; Y ₄for the DC reference voltage value under pilot project 4mA; Y ₅for leakage current values under pilot project 0.75 times of DC reference voltage; Y ₆for the power frequency reference voltage value under pilot project 1mA; Y ₇for the power frequency reference voltage value under pilot project 4mA; Y ₈for pilot project current in resistance property value; Y ₉for the running current value of pilot project compensator with series capaci tance MOV; Y ₁₀for the unsymmetrical current value of pilot project compensator with series capaci tance MOV; Y ₁₁for the working voltage value of pilot project compensator with series capaci tance MOV; Y ₁₂for the force value of pilot project compensator with series capaci tance MOV; Y ₁₃for the body temperature value of pilot project compensator with series capaci tance MOV; Y ₁₄for the ambient temperature value of pilot project compensator with series capaci tance MOV; Y ₁₅for the surface filth value of pilot project compensator with series capaci tance MOV;

S5, the risk probability of happening set up according to the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, relation in conjunction with characteristic quantity and fault mode is associated matrix M, its size is B × N, B represents total classification size of fault mode, the total quantity of N representation feature amount, the element M of its incidence matrices M _ijcomputational methods such as formula (3);

$M_{\mathrm{ij}}=\frac{\underset{j}{\min }\underset{i}{\min }|D_j-D_i|+\mathrm{\ξ}\underset{j}{\max }\underset{i}{\max }|D_j-D_i|}{|D_j-D_i|+\mathrm{\ξ}\underset{j}{\max }\underset{i}{\max }|D_j-D_i|}---\left(3\right)$

D in formula _jand D _irepresent characteristic of correspondence amount under jth and i kind fault mode respectively, ξ is resolution ratio, and span is (0,1);

S6, sets up the risk assessment of compensator with series capaci tance MOV methods of risk assessment

According to the characteristic quantity of compensator with series capaci tance MOV methods of risk assessment, risk probability of happening and fault mode incidence matrices, set up for MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, the risk assessment of composite silicone rubber material umbrella cover unit, under its computational methods:

Utilize formula calculate MOV valve block unit, aluminum annular-shaped conductive cushion block unit, coolant unit, epoxy resins insulation cartridge unit, five risk assessment values of the fault mode of composite silicone rubber material umbrella cover unit; Wherein A in formula _jfor the value-at-risk of jth kind fault mode, the span of j is the natural number of 1 to 5, and N is the total quantity of characteristic quantity, and w (i) represents the weight of i characteristic quantity for j kind fault mode, and span is (0,1);

Choose the value-at-risk of maximum as compensator with series capaci tance MOV of these five risk assessment values.