CN104537237A - Method for evaluating service life of electric transmission and transformation equipment under functions of various time-varying stresses - Google Patents

Abstract

The invention discloses a method for evaluating the service life of electric transmission and transformation equipment under functions of various time-varying stresses. According to the linear cumulative damage theory, cumulative effects of the various time-varying stresses, such as thermal stress, electrical stress, mechanical stress and random stress, on the electric transmission and transformation equipment are taken into consideration, an hour is taken as a computing unit, stress values of different time periods can be different, and time variability of the stresses is taken into consideration. By means of the concept of service life loss, influences of different kinds of stresses on the electric transmission and transformation equipment are measured in a unified mode, and comprehensive influences of the stresses are considered on the basis, so that the service life result, obtained through calculation, of the electric transmission and transformation equipment is more accurate, better accords with actual situations, and has better guidance significance in engineering application.

Description

Power transmission and transforming equipment lifetime estimation method under varying stress effect time multiple

Technical field

The invention belongs to electricity field, to particularly relate to when multiple power transmission and transforming equipment lifetime estimation method under varying stress effect.

Background technology

Power System Reliability refers to that electric system is by acceptable quality level (AQL) and requirement measuring incessantly to the ability of power consumer supply electric power and electric energy, and it is most important in electric system one of to study a question all the time.Along with the increasing of modern power systems scale, and user's improving constantly that the quality of power supply is required, the particularly generation of large-scale blackout several times both domestic and external, the safe reliability of electric system causes the great attention of people.Electric system is a complication system be made up of electrical equipments such as generator, transformer, isolating switch, transmission facility, consumers, can these electrical equipments will directly decide the safety and reliability of whole electric system by safe and reliable operation, as can be seen here, the reliability of electrical equipment is the basis of Power System Reliability, and the reliability assessment of electrical equipment is the important component part of whole Model in Reliability Evaluation of Power Systems.

According to China about the statistics of electric system is learnt, between 2003-2013 years, the ratio of the power system accident caused by electrical equipment faults itself shared by the whole fault of electric system, in the trend increased year by year, has the power system accident of more than 60% to be caused by electrical equipment malfunction every year.For Yunnan Province in 2010, the larger power system accident that Yunnan Power Grid Company occurs had 30, and wherein, the accident caused by electrical equipment malfunction accounts for 21, is about 70% of total number of accident.From the power system accident statistics of other country, situation is also like this, according to the analysis result of domestic and international electric system large-scale blackout reason, electrical equipment faults itself is not only the main cause affecting electric system reliability service, and is that in electric power system fault, proportion is maximum.

Compared to people, electrical equipment also has its life-span, i.e. the serviceable life of electrical equipment.In length of life, electrical equipment also can " sick ", namely breaks down.Under the effect of various external force, electrical equipment can produce certain damage, along with damage constantly accumulation, and material is constantly aging, intensity will constantly reduce, and finally makes the damage of electrical equipment generation part, even overall damage, cause electrical equipment cannot realize normal function, so, also just indicate the termination in this electrical equipment serviceable life.If can predict accurately the residual life of current electrical equipment, and use rational maintenance measure, the optimization in electrical equipment life-span just can be realized.In order to effectively extend the serviceable life of electrical equipment, and provide scientific basis for the optimum balance realized between the safe handling of electrical equipment and economic benefit, just need electrical equipment, particularly in transformer station and power plant, power transmission and transforming equipment carries out residual life evaluation, and how scientifically to assess its residual life be a problem demanding prompt solution.

Summary of the invention

In order to solve the problem, provided by the invention multiple time varying stress effect under power transmission and transforming equipment lifetime estimation method, calculate according to following 3 steps:

S1: obtain the sustained stress be subject in power transmission and transforming equipment section t working time, sustained stress comprises thermal stress, electric stress and mechanical stress, time period t is divided into n unit interval section t _Δ, be designated as t ₁, t ₂t _n, thermal stress is wherein with the first hot(test)-spot temperature θ ₁, θ ₂, θ _nrepresent, electric stress is with the first field intensity E ₁, E ₂e _nrepresent, mechanical stress is with the first mechanical stress M ₁, M ₂, M _nrepresent;

Obtain the random stress be subject in power transmission and transforming equipment section t working time, random stress comprises overload shock stress, lightning impulse stress and external short circuit shock stress, and wherein overload shock stress is with power transmission and transforming equipment second hot area temperature θ _o1, θ _o2, θ _oxwith corresponding overload number of shocks n _o1, n _o2, n _oxrepresent, lightning impulse stress is with the second voltage U _l1, U _l2, U _lxwith corresponding lightning impulse frequency n _l1, n _l2, n _lxrepresent, external short circuit shock stress is with the second electric current I _s1, I _s2, I _sxwith corresponding short-circuit impact frequency n _s1, n _s2, n _sxrepresent;

S2: to thermal stress, according to arrhenius model, calculates respectively at the first hot(test)-spot temperature θ ₁, θ ₂, θ _nunder power transmission and transforming equipment heat serviceable life calculate such as formula shown in (1):

$L_{\mathrm{\θ}}=\mathrm{aexp}\left(\frac{b}{\mathrm{\θ}+273}\right)---\left(1\right)$

L in model _θfor power transmission and transforming equipment heat serviceable life, a, b are the electric pressure with power transmission and transforming equipment, the constant that the factors such as the classification of insulating paper are relevant, and the preferred value of a, b is 1.7 × 10 ^-12(hour), 15000, θ is hot(test)-spot temperature, calculates respectively at the first hot(test)-spot temperature θ ₁, θ ₂, θ _nunder power transmission and transforming equipment heat serviceable life according to hot serviceable life calculate power transmission and transforming equipment in period t due to thermal life loss d that thermal stress causes _θfor formula (2):

$d_{\mathrm{\θ}}=\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θ}1}}+\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θ}2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θn}}}---\left(2\right)$

To electric stress, according to anti-power model, calculate respectively at the first field intensity E ₁, E ₂e _nunder power transmission and transforming equipment electricity serviceable life L _e1, L _e2, L _enfor formula (3):

L _E＝c(E/E ₀) ^-z(3)

L in model _efor electric serviceable life, E is field intensity, and c, z are constant, and preferred value is 3.9 × 10 ⁸(hour), E ₀for reference field intensity, preferred value is 5.0 (kV/mm); According to electricity L in serviceable life _e1, L _e2, L _en, calculate power transmission and transforming equipment in period t due to electric life loss d that electric stress causes _efor formula (4):

$d_E=\frac{t_{\mathrm{\Δ}}}{L_{E_1}}+\frac{t_{\mathrm{\Δ}}}{L_{E_2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{E_n}}---\left(4\right)$

To mechanical stress, according to anti-power model, calculate respectively at the first mechanical stress M ₁, M ₂, M _nunder power transmission and transforming equipment machinery serviceable life L _m1, L _m2, L _mnfor formula (5):

L _M＝e(M/M ₀) ^-f(5)

L in model _mfor mechanical serviceable life, M is mechanical stress, and e, f are constant, and preferred value is 3.9 × 10 ⁸(hour), 2.3, M ₀for reference mechanical stress, preferred value is 2.4 × 10 ^-4(N/mm ²); According to machinery L in serviceable life _m1, L _m2, L _mn, calculate power transmission and transforming equipment in period t due to loss mechanical life d that mechanical stress causes _mfor formula (6):

$d_M=\frac{t_{\mathrm{\Δ}}}{L_{M_1}}+\frac{t_{\mathrm{\Δ}}}{L_{M_2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{M_n}}---\left(6\right)$

To overload shock stress, according to arrhenius model, calculate power transmission and transforming equipment at second hot area temperature θ _o1, θ _o2, θ _oxthe total overload times N can born down _o1, N _o2, N _ox; According to the total overload times N that can bear _o1, N _o2, N _ox, calculate the overload that power transmission and transforming equipment causes due to overload shock stress in period t and impact life consumption for formula (7):

$d_{{\mathrm{\θ}}_o}=\frac{n_{o1}}{N_{o1}}+\frac{n_{o2}}{N_{o2}}+...+\frac{n_{\mathrm{ox}}}{N_{\mathrm{ox}}}---\left(7\right)$

To lightning impulse stress, according to existing power transmission and transforming equipment U-N curve, obtain power transmission and transforming equipment in the second voltage U _l1, U _l2, U _lxthe total lightning impulse times N can born down _l1, N _l2, N _lx; According to the total lightning impulse times N that can bear _l1, N _l2, N _lx, calculate power transmission and transforming equipment in period t due to lightning impulse life consumption that lightning impulse stress causes for formula (8):

$d_{U_l}=\frac{n_{l1}}{N_{l1}}+\frac{n_{l2}}{N_{l2}}+...+\frac{n_{\mathrm{lx}}}{N_{\mathrm{lx}}}---\left(8\right)$

To outside short-circuit impact stress, according to existing power transmission and transforming equipment I-N curve, obtain power transmission and transforming equipment in the second electric current I _s1, I _s2, I _sxthe total short-circuit impact times N can born down _s1, N _s2, N _sx; According to the total short-circuit impact times N that can bear _s1, N _s2, N _sx, calculate power transmission and transforming equipment in period t due to short-circuit impact life consumption that external short circuit shock stress causes for formula (9):

$d_{\mathrm{Is}}=\frac{n_{s1}}{N_{s1}}+\frac{n_{s2}}{N_{s2}}+...+\frac{n_{\mathrm{sx}}}{N_{\mathrm{sx}}}---\left(9\right)$

In period t, the power transmission and transforming equipment life consumption caused by all stress is formula (10):

$d=d_{\mathrm{\θ}}+d_E+d_M+d_{{\mathrm{\θ}}_o}+d_{U_l}+d_{I_s}---\left(10\right)$

S3: calculate the T=T+t moment, the accumulation life consumption D=D+d of power transmission and transforming equipment, judges D, if D is greater than 1, then show that power transmission and transforming equipment expires serviceable life, namely the estimated life of power transmission and transforming equipment is L=T; If D is less than 1, then show that power transmission and transforming equipment is not yet due for serviceable life, step S2 repeats to calculate, until power transmission and transforming equipment end of life.

The present invention compared with the existing technology, have the following advantages and beneficial effect: residue lifetime estimation method under varying stress effect when how aging the present invention propose, according to linear cumulative damage law, when considering various by thermal stress, electric stress, mechanical stress, random stress etc., varying stress is to the cumulative function of power transmission and transforming equipment, with the little period for unit of account, the stress value of Different periods can be different, taken into account by the time variation of stress.Adopt the concept of life consumption that variety classes stress is affected unified metric to power transmission and transforming equipment, and consider the combined influence of multiple stress on this basis, the result in serviceable life of the power transmission and transforming equipment therefore calculated is more accurate, more tally with the actual situation, thus directive significance is had more to engineer applied.

Embodiment

Below technical scheme of the present invention is clearly and completely described.Power transmission and transforming equipment lifetime estimation method under varying stress effect time multiple, calculates according to following 3 steps:

S1: obtain the sustained stress be subject in power transmission and transforming equipment section t working time, sustained stress comprises thermal stress, electric stress and mechanical stress, time period t is divided into n unit interval section t _Δ, be designated as t ₁, t ₂t _n, thermal stress is wherein with the first hot(test)-spot temperature θ ₁, θ ₂, θ _nrepresent, electric stress is with the first field intensity E ₁, E ₂e _nrepresent, mechanical stress is with the first mechanical stress M ₁, M ₂, M _nrepresent;

Obtain the random stress be subject in power transmission and transforming equipment section t working time, random stress comprises overload shock stress, lightning impulse stress and external short circuit shock stress, and wherein overload shock stress is with power transmission and transforming equipment second hot area temperature θ _o1, θ _o2, θ _oxwith corresponding overload number of shocks n _o1, n _o2, n _oxrepresent, lightning impulse stress is with the second voltage U _l1, U _l2, U _lxwith corresponding lightning impulse frequency n _l1, n _l2, n _lxrepresent, external short circuit shock stress is with the second electric current I _s1, I _s2, I _sxwith corresponding short-circuit impact frequency n _s1, n _s2, n _sxrepresent;

S2: to thermal stress, according to arrhenius model, calculates respectively at the first hot(test)-spot temperature θ ₁, θ ₂, θ _nunder power transmission and transforming equipment heat serviceable life calculate such as formula shown in (1):

$L_{\mathrm{\θ}}=\mathrm{aexp}\left(\frac{b}{\mathrm{\θ}+273}\right)---\left(1\right)$

L in model _θfor power transmission and transforming equipment heat serviceable life, a, b are the electric pressure with power transmission and transforming equipment, the constant that the factors such as the classification of insulating paper are relevant, and the preferred value of a, b is 1.7 × 10 ^-12(hour), 15000, θ is hot(test)-spot temperature, calculates respectively at the first hot(test)-spot temperature θ ₁, θ ₂, θ _nunder power transmission and transforming equipment heat serviceable life according to hot serviceable life calculate power transmission and transforming equipment in period t due to thermal life loss d that thermal stress causes _θfor formula (2):

$d_{\mathrm{\θ}}=\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θ}1}}+\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θ}2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θn}}}---\left(2\right)$

To electric stress, according to anti-power model, calculate respectively at the first field intensity E ₁, E ₂e _nunder power transmission and transforming equipment electricity serviceable life L _e1, L _e2, L _enfor formula (3):

L _E＝c(E/E ₀) ^-z(3)

L in model _efor electric serviceable life, E is field intensity, and c, z are constant, and preferred value is 3.9 × 10 ⁸(hour), E ₀for reference field intensity, preferred value is 5.0 (kV/mm); According to electricity L in serviceable life _e1, L _e2, L _en, calculate power transmission and transforming equipment in period t due to electric life loss d that electric stress causes _efor formula (4):

$d_E=\frac{t_{\mathrm{\Δ}}}{L_{E_1}}+\frac{t_{\mathrm{\Δ}}}{L_{E_2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{E_n}}---\left(4\right)$

To mechanical stress, according to anti-power model, calculate respectively at the first mechanical stress M ₁, M ₂, M _nunder power transmission and transforming equipment machinery serviceable life L _m1, L _m2, L _mnfor formula (5):

L _M＝e(M/M ₀) ^-f(5)

L in model _mfor mechanical serviceable life, M is mechanical stress, and e, f are constant, and preferred value is 3.9 × 10 ⁸(hour), 2.3, M ₀for reference mechanical stress, preferred value is 2.4 × 10 ^-4(N/mm ²); According to machinery L in serviceable life _m1, L _m2, L _mn, calculate power transmission and transforming equipment in period t due to loss mechanical life d that mechanical stress causes _mfor formula (6):

$d_M=\frac{t_{\mathrm{\Δ}}}{L_{M_1}}+\frac{t_{\mathrm{\Δ}}}{L_{M_2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{M_n}}---\left(6\right)$

To overload shock stress, according to arrhenius model, calculate power transmission and transforming equipment at second hot area temperature θ _o1, θ _o2, θ _oxthe total overload times N can born down _o1, N _o2, N _ox; According to the total overload times N that can bear _o1, N _o2, N _ox, calculate the overload that power transmission and transforming equipment causes due to overload shock stress in period t and impact life consumption for formula (7):

$d_{{\mathrm{\θ}}_o}=\frac{n_{o1}}{N_{o1}}+\frac{n_{o2}}{N_{o2}}+...+\frac{n_{\mathrm{ox}}}{N_{\mathrm{ox}}}---\left(7\right)$

To lightning impulse stress, according to existing power transmission and transforming equipment U-N curve, obtain power transmission and transforming equipment in the second voltage U _l1, U _l2, U _lxthe total lightning impulse times N can born down _l1, N _l2, N _lx; According to the total lightning impulse times N that can bear _l1, N _l2, N _lx, calculate power transmission and transforming equipment in period t due to lightning impulse life consumption that lightning impulse stress causes for formula (8):

$d_{U_l}=\frac{n_{l1}}{N_{l1}}+\frac{n_{l2}}{N_{l2}}+...+\frac{n_{\mathrm{lx}}}{N_{\mathrm{lx}}}---\left(8\right)$

To outside short-circuit impact stress, according to existing power transmission and transforming equipment I-N curve, obtain power transmission and transforming equipment in the second electric current I _s1, I _s2, I _sxthe total short-circuit impact times N can born down _s1, N _s2, N _sx; According to the total short-circuit impact times N that can bear _s1, N _s2, N _sx, calculate power transmission and transforming equipment in period t due to short-circuit impact life consumption that external short circuit shock stress causes for formula (9):

$d_{\mathrm{Is}}=\frac{n_{s1}}{N_{s1}}+\frac{n_{s2}}{N_{s2}}+...+\frac{n_{\mathrm{sx}}}{N_{\mathrm{sx}}}---\left(9\right)$

In period t, the power transmission and transforming equipment life consumption caused by all stress is formula (10):

$d=d_{\mathrm{\θ}}+d_E+d_M+d_{{\mathrm{\θ}}_o}+d_{U_l}+d_{I_s}---\left(10\right)$

S3: calculate the T=T+t moment, the accumulation life consumption D=D+d of power transmission and transforming equipment, judges D, if D is greater than 1, then show that power transmission and transforming equipment expires serviceable life, namely the estimated life of power transmission and transforming equipment is L=T; If D is less than 1, then show that power transmission and transforming equipment is not yet due for serviceable life, step S2 repeats to calculate, until power transmission and transforming equipment end of life.

Claims (1)

1. many kinds time varying stress effect under power transmission and transforming equipment lifetime estimation method, it is characterized in that, calculate according to following three steps:

S1: obtain the sustained stress be subject in power transmission and transforming equipment section t working time, sustained stress comprises thermal stress, electric stress and mechanical stress, time period t is divided into n unit interval section t _Δ, be designated as t ₁, t ₂t _n, thermal stress is wherein with the first hot(test)-spot temperature θ ₁, θ ₂, θ _nrepresent, electric stress is with the first field intensity E ₁, E ₂e _nrepresent, mechanical stress is with the first mechanical stress M ₁, M ₂, M _nrepresent;

Obtain the random stress be subject in power transmission and transforming equipment section t working time, random stress comprises overload shock stress, lightning impulse stress and external short circuit shock stress, and wherein overload shock stress is with power transmission and transforming equipment second hot area temperature θ _o1, θ _o2, θ _oxwith corresponding overload number of shocks n _o1, n _o2, n _oxrepresent, lightning impulse stress is with the second voltage U _l1, U _l2, U _lxwith corresponding lightning impulse frequency n _l1, n _l2, n _lxrepresent, external short circuit shock stress is with the second electric current I _s1, I _s2, I _sxwith corresponding short-circuit impact frequency n _s1, n _s2, n _sxrepresent;

S2: to thermal stress, according to arrhenius model, calculates respectively at the first hot(test)-spot temperature θ ₁, θ ₂, θ _nunder power transmission and transforming equipment heat serviceable life calculate such as formula shown in (1):

$L_{\mathrm{\θ}}=\mathrm{a\; exp}\left(\frac{b}{\mathrm{\θ}+273}\right)---\left(1\right)$

L in model _θfor power transmission and transforming equipment heat serviceable life, a, b are the electric pressure with power transmission and transforming equipment, the constant that the classification factor of insulating paper is relevant, and θ is hot(test)-spot temperature, calculates respectively at the first hot(test)-spot temperature θ ₁, θ ₂, θ _nunder power transmission and transforming equipment heat serviceable life according to hot serviceable life calculate power transmission and transforming equipment in period t due to thermal life loss d that thermal stress causes _θfor formula (2):

$d_{\mathrm{\θ}}=\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θ}1}}+\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θ}2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{\mathrm{\θn}}}---\left(2\right)$

To electric stress, according to anti-power model, calculate respectively at the first field intensity E ₁, E ₂e _nunder power transmission and transforming equipment electricity serviceable life L _e1, L _e2, L _enfor formula (3):

L _E＝c(E/E ₀) ^-z(3)

L in model _efor electric serviceable life, E is field intensity, and c, z are constant, E ₀for reference field intensity; According to electricity L in serviceable life _e1, L _e2, L _en, calculate power transmission and transforming equipment in period t due to electric life loss d that electric stress causes _efor formula (4):

$d_E=\frac{t_{\mathrm{\Δ}}}{L_{E_1}}+\frac{t_{\mathrm{\Δ}}}{L_{E_2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{E_n}}---\left(4\right)$

To mechanical stress, according to anti-power model, calculate respectively at the first mechanical stress M ₁, M ₂, M _nunder power transmission and transforming equipment machinery serviceable life L _m1, L _m2, L _mnfor formula (5):

L _M＝e(M/M ₀) ^-f(5)

L in model _mfor mechanical serviceable life, M is mechanical stress, and e, f are constant, M ₀for reference mechanical stress; According to machinery L in serviceable life _m1, L _m2, L _mn, calculate power transmission and transforming equipment in period t due to loss mechanical life d that mechanical stress causes _mfor formula (6):

$d_M=\frac{t_{\mathrm{\Δ}}}{L_{M_1}}+\frac{t_{\mathrm{\Δ}}}{L_{M_2}}+...+\frac{t_{\mathrm{\Δ}}}{L_{M_n}}---\left(6\right)$

To overload shock stress, according to arrhenius model, calculate power transmission and transforming equipment at second hot area temperature θ _o1, θ _o2, θ _oxthe total overload times N can born down _o1, N _o2, N _ox; According to the total overload times N that can bear _o1, N _o2, N _ox, calculate the overload that power transmission and transforming equipment causes due to overload shock stress in period t and impact life consumption for formula (7):

$d_{{\mathrm{\θ}}_o}=\frac{n_{o1}}{N_{o1}}+\frac{n_{o2}}{N_{o2}}+...+\frac{n_{\mathrm{ox}}}{N_{\mathrm{ox}}}---\left(7\right)$

To lightning impulse stress, according to existing power transmission and transforming equipment U-N curve, obtain power transmission and transforming equipment in the second voltage U _l1, U _l2, U _lxthe total lightning impulse times N can born down _l1, N _l2, N _lx,

According to the total lightning impulse times N that can bear _l1, N _l2, N _lx, calculate power transmission and transforming equipment in period t due to lightning impulse life consumption that lightning impulse stress causes for formula (8):

$d_{U_l}=\frac{n_{l1}}{N_{l1}}+\frac{n_{l2}}{N_{l2}}+...+\frac{n_{\mathrm{lx}}}{N_{\mathrm{lx}}}---\left(8\right)$

To outside short-circuit impact stress, according to existing power transmission and transforming equipment I-N curve, obtain power transmission and transforming equipment in the second electric current I _s1, I _s2, I _sxthe total short-circuit impact times N can born down _s1, N _s2, N _sx; According to the total short-circuit impact times N that can bear _s1, N _s2, N _sx, calculate power transmission and transforming equipment in period t due to short-circuit impact life consumption that external short circuit shock stress causes for formula (9):

$d_{\mathrm{Is}}=\frac{n_{s1}}{N_{s1}}+\frac{n_{s2}}{N_{s2}}+...+\frac{n_{\mathrm{sx}}}{N_{\mathrm{sx}}}---\left(9\right)$

In period t, the power transmission and transforming equipment life consumption caused by all stress is formula (10):

$d=d_{\mathrm{\θ}}+d_E+d_M+D_{{\mathrm{\θ}}_o}+d_{U_l}+d_{I_s}---\left(10\right)$

S3: calculate the T=T+t moment, the accumulation life consumption D=D+d of power transmission and transforming equipment, judges D, if D is greater than 1, then show that power transmission and transforming equipment expires serviceable life, namely the estimated life of power transmission and transforming equipment is L=T; If D is less than 1, then show that power transmission and transforming equipment is not yet due for serviceable life, step S2 repeats to calculate, until power transmission and transforming equipment end of life.