CN104392277A - Transformer economy service life predication method and device - Google Patents

Abstract

A transformer economy service life predication device is sequentially connected by an input parameter receiving and delivering module (1), a process calculation module (2) and a data fitting contrastive analysis module (6) and a constant management module (3), a constant library (4), a constant interaction module (5) and a process calculation module (2). According to the transformer economy service life predication device, the economy service life of a transformer can be accurately calculated, an application system for transformer economy service life evaluation can be rapidly formed due to combination of a calculation model, the evaluation principle and the computer technology, and a time reference point is provided for transformer maintenance and replacement.

Description

A kind of transformer economy life-span prediction method and device

Technical field

The present invention relates to transformer economic factor analytical technology, transformer economy Life Assessment Technology, Technology of Data Fitting.

Background technology

Power transformation link is as the key and the basis that realize strong intelligent grid, and fault diagnosis and the repair and maintenance strategy of building smart grid-oriented become common recognition.Along with the rapid expansion of electrical network scale, the ultimate challenge that grid company equipment control faces how to pursue the most efficient plant asset management of one, ensures the safety of production, meets power grid security requirement, the realization of the long-range strategic objective of the company that serves.

But, converting equipment is effectively managed, not only relates to equipment and technology aspect, also comprise economic aspect.At economic aspect, assisted by annual cost in life cycle of assessment apparatus overall life cycle cost or equipment and maintenance policy, for the technological transformation of equipment or replacing provide foundation.Operating cost and the maintenance cost of some converting equipments (as transformer) are higher, and it generally reaches 6 ~ 7 times of purchase commodity in life cycle.Therefore, when the equipment of selection except considering the acquisition expenses of equipment, the operating cost of the performance parameter of equipment on equipment and the impact of maintenance cost must be considered, like this can comprehensive assessment apparatus life cycle cost, to select best converting equipment and best maintenance strategy.

But current China power equipment lacks a kind of fault diagnosis of science and maintenance and retired strategy, usually using in-service year number length as Main Basis.Owing to lacking the assessment to power equipment virtual condition, usually can cause originally can continuing be on active service and by retired in advance, cause huge waste.Power equipment is the core asset of power grid enterprises, how to formulate maintenance economically to plan with renewal, reasonable prolongation comprises the power equipment life-span of power transformer, effectively promotes the utilization factor of core asset, has become the focal point of countries in the world electric power enterprise and related research institutes.Comparatively speaking, the research of China in power equipment operation management is very few, lacks the research to power equipment life characteristics, does not have the retired decision-making foundation of science, and the retired age of power equipment is far below world level.The average enlistment age of the power transformer such as, run in united states, japan and other countries current electric grid is more than 40a, and China is just retired less than 30a greatly.In fact, a big chunk in retired still can continue to run.For the electrical network scale that China is such, service life of power transformer often extends 1a and just has number in net proceeds necessarily.

A kind of based on maintenance with change the transformer economy life-span prediction method of average annual net proceeds trend comparative analysis under model and device can economy life-span of Accurate Prediction transformer, by the trend analysis of maintenance with average annual net proceeds under replacing model, when overhaul time average annual net proceeds lower than change time average annual net proceeds time, then this transformer should be changed, the economy life-span of transformer is determined with this node, efficiently solve the problem that current transformer is retired in advance, management for transformer provides the retired decision-making foundation of science, reduce transformer because shifting to an earlier date the retired economic loss caused, improve the utilization factor of core asset.

Summary of the invention

The present invention is by using transformer economic factor analytical technology, transformer economy Life Assessment Technology, Technology of Data Fitting etc., transformer economic factor is analyzed, propose the computation model of parameters and clearly whole calculation process, define a set of method in order to predict the transformer economy life-span and device.

The present invention, in conjunction with transformer actual operating state, analyzes transformer economy life-span key element, as shown in transformer economy life-span element structure figure: transformer economy life-span key element be divided into maintenance economic factor and change economic factor.Wherein, maintenance economic factor comprises income and the cost of overhaul, income and general income of power supply, and the cost of overhaul comprises operation expense, accident risk cost, broad sense depreciable cost and the cost of overhaul; Change economic factor and comprise income and replacement cost, income and general income of power supply, replacement cost comprises operation expense, accident risk cost and broad sense depreciable cost.

A kind of transformer economy life predication apparatus, by inputting, parameter receives/delivers module to this device, process computation module, data fitting comparative analysis module sequentially connect; Constant administration module, constant storehouse, constant interactive module, process computation module sequentially connect;

Wherein, process computation module comprises probability of malfunction function computation module A1, probability of malfunction function computation module B1, equivalence time expand computing module A2, equivalence time expand computing module B2, maintenance model and changes model;

Described maintenance model comprises the total cost computing module A5 under power supply income calculation modules A 3, operation expense computing module A6, accident risk pricing modules A 7, calculation of maintenance cost modules A 8, broad sense depreciable cost computing module A9, maintenance solution, average annual net proceeds computing module A4;

Described replacing model comprises the total cost computing module B5 under power supply income calculation module B3, operation expense computing module B6, accident risk pricing module B7, broad sense depreciable cost computing module B8, Replacing Scheme, average annual net proceeds computing module B4;

Annexation is:

Input parameter receives/delivers module and is connected with power supply income calculation modules A 3, equivalence time expand computing module A2, probability of malfunction function computation module A1, broad sense depreciable cost computing module A9 respectively; Probability of malfunction function computation module A1 is connected with equivalence time expand computing module A2, accident risk pricing modules A 7 respectively; Equivalence time expand computing module A2 is connected with power supply income calculation modules A 3, operation expense computing module A6 respectively; Operation expense computing module A6, accident risk pricing modules A 7, calculation of maintenance cost modules A 8, broad sense depreciable cost computing module A9 are connected with the total cost computing module A5 under maintenance solution respectively; Total cost computing module A5 under power supply income calculation modules A 3, maintenance solution is connected with average annual net proceeds computing module A4 respectively;

Input parameter receives/delivers module and is connected with operation expense computing module B6, probability of malfunction function computation module B1, equivalence time expand computing module B2, income calculation of powering module B3 respectively; Probability of malfunction function computation module B1 is connected with equivalence time expand computing module B2, accident risk pricing module B7 respectively; Equivalence time expand computing module B2 is connected with broad sense depreciable cost computing module B8; Operation expense computing module B6, accident risk pricing module B7, broad sense depreciable cost computing module B8 are connected with the total cost computing module B5 under Replacing Scheme respectively; Total cost computing module B5 under Replacing Scheme, power supply income calculation module B3 are connected with average annual net proceeds computing module B4 respectively; Average annual net proceeds computing module A4, average annual net proceeds computing module B4 are connected with data fitting comparative analysis module respectively.

According to transformer economy life-span element structure figure (see photo), principle of compositionality of the present invention is as shown in transformer economy life appraisal schematic diagram: receive/deliver module by input parameter, process computation module, constant administration module, constant storehouse (constant value sees attached list table 1 constant table), constant interactive module, data fitting comparative analysis mould form.Wherein, process computation module comprises equivalence time expand computing module, probability of malfunction function computation module, maintenance model and changes model.

The data dependence relation of calculation process of the present invention and intermodule is as shown in transformer economy life appraisal schematic diagram: input parameter receives/delivers input parameter (see attached list table 2 and input parameter table) Auto-matching that user inputs by module and is delivered to equivalent time expand computing module in process computation module respectively, probability of malfunction function computation module, maintenance model is with under replacing model, then undertaken alternately by constant interactive module and constant storehouse (constant value sees attached list table 1 constant table), obtain the constant value of modules and submodule calculating needs thereof, after calculating according to the computation model of modules and submodule thereof, export maintenance model and average annual net proceeds (a series of values in t interval under changing model respectively, the span of t sees attached list table 1 constant table), finally by data fitting comparative analysis module, maintenance model and the average annual net proceeds changed under model are carried out curve fitting, solve the intersection point obtaining two curves, this intersection value is the transformer current economy life-span.

In modules in the present invention and the computation model of submodule thereof, about the function of transformer interval t (seeing attached list table 1 constant table) working time, its operation result is in t interval, and value step-length is a series of values of 0.01 (seeing attached list table 1 constant table).The computation model of modules of the present invention and submodule thereof is that (each variable in formula and constant parameter see attached list table 1 constant table and table 2 inputs parameter table; Note: the square frame " " in formula does not represent any compute sign, only does intersymbol separation to avoid confusion):

(1) failure rate function computing module

Failure rate function λ (t): (output of this module);

Current time trouble shooting rate fall Δ λ (t): (output of this module);

Parameter Δ s1: $\mathrm{\Δ}{s}_1=\mathrm{\η}\sqrt[m-1]{\mathrm{\λ}\frac{\mathrm{\η}}{m}}-t_0;$

Equivalence enlistment age parameter Δ s:

(2) equivalence time expand computing module

Equivalence time expand Δ q (t): $\mathrm{\Δq}\left(t\right)=\mathrm{\η}\sqrt[m-1]{\mathrm{\λ}\left(t\right)\frac{\mathrm{\η}}{m}}-\mathrm{\η}\sqrt[m-1]{[\mathrm{\λ}\left(t\right)-\mathrm{\Δ\λ}\left(t\right)]\frac{\mathrm{\η}}{m}}$ (output of this module);

(3) model is overhauled

1) power supply income calculation module

Power supply income I under maintenance model _p1: I _p1=ξ S η Δ p [t+ Δ q (t)-t ₀] (output of this module);

2) operation expense computing module

Operation expense CO ₁=CO _e1+ CO _m1(output of this module);

CO can be expended _e1: CO _e1=(P ₀+ η ²p _k) p ₁μ [t+ Δ q (t)-t ₀] 8760;

Operation and maintenance cost CO _m1: ${\mathrm{CO}}_{m1}={\mathrm{CO}}_b{\∫}_{t_0}^{t+\mathrm{\Δq}\left(t\right)}(1+{\mathrm{\α}}_{1}t)\mathrm{dt};$

3) accident risk pricing module

Accident risk cost CR ₁: qi Zhong ⊿ t=⊿ q of () (output of this module); Economic loss LOTF:LOTF=Loss after transformer breaks down ₁+ Loss ₂+ Loss ₃+ Loss ₄;

System cutting load cost Loss ₁:

The correction factor β 1: β of system risk ₁=β ₁₁× β ₁₂× β ₁₃;

Mean failure rate cost Loss ₂: Loss ₂=C _f× β ₂;

The correction factor β of rehabilitation cost ₂: β ₂=β ₂₁× β ₂₂;

Personnel risk cost Loss ₃:

Environmental costs Loss ₄(constant sees attached list table 1 constant table);

4) broad sense depreciable cost computing module

Broad sense depreciable cost CD ₁: (output of this module);

Transformer initial outlay cost CI:CI=CI _e+ CI _i+ CI _o;

The retired cost CD:CD=CD of transformer _t-CD _r;

Retired handling CDT:CD _t=CI _dcC _r;

Residual value CD when equipment is retired _r: CD _r=CI _ecca;

The loss of outage Crc (constant sees attached list table 1 constant table) of new and old transformer equipment handing-over;

5) calculation of maintenance cost module

Cost of overhaul CM1:CM ₁=CM _t+ CM _r(output of this module);

Recondition expense CM _t: CM _t=(1+ α ₂t) C _b;

Shutdown loss cost CM _r: CM _r=t _rsc _rb;

Electrical network faces shutdown risk cost C per hour because redundance declines _rb: C _rb=S Δ p α _c;

Repair time t _rs: t _rs=t _b+ α ₃t;

6) the total cost computing module under maintenance solution

Total cost C1:C under maintenance solution ₁=CO ₁+ CR ₁+ CD ₁+ CM ₁(output of this module);

7) average annual net proceeds computing module

Average annual net proceeds W ₁: (output of this module);

(4) model is changed

1) power supply income calculation module

Power supply income I _p2: I _p2=ξ S η Δ p (t-t ₀) (output of this module);

2) operation expense computing module

Operation expense CO ₂: with the operation expense computing module (output of this module) of maintenance model;

3) accident risk pricing module

Accident risk cost CR ₂: with the accident risk pricing module (output of this module) of maintenance model;

4) broad sense depreciable cost computing module

Broad sense depreciable cost CD ₂: with the broad sense depreciable cost computing module (output of this module) of maintenance model;

5) the total cost computing module under Replacing Scheme

Total cost C under Replacing Scheme ₂: C ₂=CO ₂+ CR ₂+ CD ₂(output of this module);

6) average annual net proceeds computing module

Average annual net proceeds W2: (output of this module);

(5) calculating in economy life-span

Maintenance and average annual net proceeds W1 and the W2 changed under model are carried out curve fitting by data fitting comparative analysis module by the calculating in transformer economy life-span, article two, the intersection point of curve is this transformer current economy life-span, as the matching of economy life-span solves shown in schematic diagram.

The economy life-span of transformer accurately can be calculated based on the present invention, and, by algorithm model of the present invention and the combination assessing principle and computer technology, the application system of a set of transformer economy life appraisal can be formed fast, for the maintenance of transformer and replacing provide time reference.

Accompanying drawing explanation

Fig. 1 is transformer economy life-span element structure figure of the present invention;

Fig. 2 is transformer economy life appraisal schematic diagram of the present invention;

Fig. 3 is that transformer economy life-span matching of the present invention solves schematic diagram.

Embodiment

A kind of transformer economy life predication apparatus, by inputting, parameter receives/delivers module 1 to this device, process computation module 2, data fitting comparative analysis module 6 sequentially connect; Constant administration module 3, constant storehouse 4, constant interactive module 5, process computation module 2 sequentially connect;

Wherein, process computation module 2 comprises probability of malfunction function computation module A1, probability of malfunction function computation module B1, equivalence time expand computing module A2, equivalence time expand computing module B2, maintenance model 22 and changes model 21;

Described maintenance model 22 comprises the total cost computing module A5 under power supply income calculation modules A 3, operation expense computing module A6, accident risk pricing modules A 7, calculation of maintenance cost modules A 8, broad sense depreciable cost computing module A9, maintenance solution, average annual net proceeds computing module A4;

Described replacing model 21 comprises the total cost computing module B5 under power supply income calculation module B3, operation expense computing module B6, accident risk pricing module B7, broad sense depreciable cost computing module B8, Replacing Scheme, average annual net proceeds computing module B4;

Annexation is:

Input parameter receives/delivers module 1 and is connected with power supply income calculation modules A 3, equivalence time expand computing module A2, probability of malfunction function computation module A1, broad sense depreciable cost computing module A9 respectively; Probability of malfunction function computation module A1 is connected with equivalence time expand computing module A2, accident risk pricing modules A 7 respectively; Equivalence time expand computing module A2 is connected with power supply income calculation modules A 3, operation expense computing module A6 respectively; Operation expense computing module A6, accident risk pricing modules A 7, calculation of maintenance cost modules A 8, broad sense depreciable cost computing module A9 are connected with the total cost computing module A5 under maintenance solution respectively; Total cost computing module A5 under power supply income calculation modules A 3, maintenance solution is connected with average annual net proceeds computing module A4 respectively;

Input parameter receives/delivers module 1 and is connected with operation expense computing module B6, probability of malfunction function computation module B1, equivalence time expand computing module B2, income calculation of powering module B3 respectively; Probability of malfunction function computation module B1 is connected with equivalence time expand computing module B2, accident risk pricing module B7 respectively; Equivalence time expand computing module B2 is connected with broad sense depreciable cost computing module B8; Operation expense computing module B6, accident risk pricing module B7, broad sense depreciable cost computing module B8 are connected with the total cost computing module B5 under Replacing Scheme respectively; Total cost computing module B5 under Replacing Scheme, power supply income calculation module B3 are connected with average annual net proceeds computing module B4 respectively; Average annual net proceeds computing module A4, average annual net proceeds computing module B4 are connected with data fitting comparative analysis module 6 respectively.

A kind of using method of transformer economy life predication apparatus, input parameter receives/delivers input parameter Auto-matching that user inputs by module 1 and is delivered to equivalent time expand computing module (A2/B2) in process computation module 2 respectively, probability of malfunction function computation module (A1/B1), overhaul model 22 and change model 21 times, then undertaken alternately by constant interactive module 5 and constant storehouse 4, obtain the constant value of modules and submodule calculating needs thereof, after calculating according to the computation model of modules and submodule thereof, export maintenance model 22 and the average annual net proceeds under changing model 21 respectively, finally by data fitting comparative analysis module 6, maintenance model and the average annual net proceeds changed under model are carried out curve fitting, solve the intersection point obtaining two curves, this intersection value is the transformer current economy life-span, note: the square frame " " in formula does not represent any compute sign, only does intersymbol separation to avoid confusion):

The computation model of described modules and submodule thereof is:

(1) probability of malfunction function computation module

Failure rate function λ (t): $\mathrm{\λ}\left(t\right)=\frac{m}{\mathrm{\η}}{\left(\frac{t+\mathrm{\Δs}}{\mathrm{\η}}\right)}^{m-1};$

Current time trouble shooting rate fall Δ λ (t):

Parameter Δ s1: $\mathrm{\Δ}{s}_1=\mathrm{\η}\sqrt[m-1]{\mathrm{\λ}\frac{\mathrm{\η}}{m}}-t_0;$

Equivalence enlistment age parameter Δ s:

(2) equivalence time expand computing module

Equivalence time expand Δ q (t): $\mathrm{\Δq}\left(t\right)=\mathrm{\η}\sqrt[m-1]{\mathrm{\λ}\left(t\right)\frac{\mathrm{\η}}{m}}-\mathrm{\η}\sqrt[m-1]{[\mathrm{\λ}\left(t\right)-\mathrm{\Δ\λ}\left(t\right)]\frac{\mathrm{\η}}{m}};$

(3) model is overhauled

8) power supply income calculation module

Power supply income I under maintenance model _p1: I _p1=ξ S η Δ p [t+ Δ q (t)-t ₀];

9) operation expense computing module

Operation expense CO ₁=CO _e1+ CO _m1;

CO can be expended _e1: CO _e1=(P ₀+ η ²p _k) p ₁μ [t+ Δ q (t)-t ₀] 8760;

Operation and maintenance cost CO _m1: ${\mathrm{CO}}_{m1}={\mathrm{CO}}_b{\∫}_{t_0}^{t+\mathrm{\Δq}\left(t\right)}(1+{\mathrm{\α}}_{1}t)\mathrm{dt};$

10) accident risk pricing module

Accident risk cost CR ₁: qi Zhong ⊿ t=⊿ q;

Economic loss LOTF:LOTF=Loss after transformer breaks down ₁+ Loss ₂+ Loss ₃+ Loss ₄;

System cutting load cost Loss ₁:

The correction factor β 1: β of system risk ₁=β ₁₁× β ₁₂× β ₁₃;

Mean failure rate cost Loss ₂: Loss ₂=C _f× β ₂;

The correction factor β of rehabilitation cost ₂: β ₂=β ₂₁× β ₂₂;

Personnel risk cost Loss ₃:

Environmental costs Loss ₄for constant;

11) broad sense depreciable cost computing module

Broad sense depreciable cost CD ₁: ${\mathrm{CD}}_1=(\mathrm{CI}+\mathrm{CD}+C_{\mathrm{rc}})\frac{t-t_0}{T_{\mathrm{dl}}};$

Transformer initial outlay cost CI:CI=CI _e+ CI _i+ CI _o;

The retired cost CD:CD=CD of transformer _t-CD _r;

Retired handling CD _t: CD _t=CI _dcC _r;

Residual value CD when equipment is retired _r: CD _r=CI _ecca;

The loss of outage Crc of new and old transformer equipment handing-over is constant;

12) calculation of maintenance cost module

Cost of overhaul CM1:CM ₁=CM _t+ CM _r;

Recondition expense CM _t: CM _t=(1+ α ₂t) C _b;

Shutdown loss cost CM _r: CM _r=t _rsc _rb;

Electrical network faces shutdown risk cost C per hour because redundance declines _rb: C _rb=S Δ p α _c;

Repair time t _rs: t _rs=t _b+ α ₃t;

13) the total cost computing module under maintenance solution

Total cost C under maintenance solution ₁: C ₁=CO ₁+ CR ₁+ CD ₁+ CM ₁;

14) average annual net proceeds computing module

Average annual net proceeds W ₁: $W_1=\frac{I_{P1}-C_1}{t+\mathrm{\Δq}\left(t\right)-t_0};$

(4) model is changed

7) power supply income calculation module

Power supply income I _p2: I _p2=ξ S η Δ p (t-t ₀);

8) operation expense computing module

Operation expense CO ₂: with the operation expense computing module of maintenance model;

9) accident risk pricing module

Accident risk cost CR ₂: with the accident risk pricing module of maintenance model;

10) broad sense depreciable cost computing module

Broad sense depreciable cost CD ₂: with the broad sense depreciable cost computing module of maintenance model;

11) the total cost computing module under Replacing Scheme

Total cost C under Replacing Scheme ₂: C ₂=CO ₂+ CR ₂+ CD ₂;

12) average annual net proceeds computing module

Average annual net proceeds W2:

(5) calculating in economy life-span

Maintenance and average annual net proceeds W1 and the W2 changed under model are carried out curve fitting by data fitting comparative analysis module by the calculating in transformer economy life-span, and the intersection point of two curves is this transformer current economy life-span.

Subordinate list:

Table 1 constant table

Table 2 inputs parameter table

Claims (2)

1. a transformer economy life predication apparatus, is characterized in that, by inputting, parameter receives/deliver module (1) to this device, process computation module (2), data fitting comparative analysis module (6) sequentially connect; Constant administration module (3), constant storehouse (4), constant interactive module (5), process computation module (2) sequentially connect;

Wherein, process computation module (2) comprises probability of malfunction function computation module A1, probability of malfunction function computation module B1, equivalence time expand computing module A2, equivalence time expand computing module B2, maintenance model (22) and changes model (21);

Described maintenance model (22) comprises the total cost computing module A5 under power supply income calculation modules A 3, operation expense computing module A6, accident risk pricing modules A 7, calculation of maintenance cost modules A 8, broad sense depreciable cost computing module A9, maintenance solution, average annual net proceeds computing module A4;

Described replacing model (21) comprises the total cost computing module B5 under power supply income calculation module B3, operation expense computing module B6, accident risk pricing module B7, broad sense depreciable cost computing module B8, Replacing Scheme, average annual net proceeds computing module B4;

Annexation is:

Input parameter receives/delivers module (1) and is connected with power supply income calculation modules A 3, equivalence time expand computing module A2, probability of malfunction function computation module A1, broad sense depreciable cost computing module A9 respectively; Probability of malfunction function computation module A1 is connected with equivalence time expand computing module A2, accident risk pricing modules A 7 respectively; Equivalence time expand computing module A2 is connected with power supply income calculation modules A 3, operation expense computing module A6 respectively; Operation expense computing module A6, accident risk pricing modules A 7, calculation of maintenance cost modules A 8, broad sense depreciable cost computing module A9 are connected with the total cost computing module A5 under maintenance solution respectively; Total cost computing module A5 under power supply income calculation modules A 3, maintenance solution is connected with average annual net proceeds computing module A4 respectively;

Input parameter receives/delivers module (1) and is connected with operation expense computing module B6, probability of malfunction function computation module B1, equivalence time expand computing module B2, income calculation of powering module B3 respectively; Probability of malfunction function computation module B1 is connected with equivalence time expand computing module B2, accident risk pricing module B7 respectively; Equivalence time expand computing module B2 is connected with broad sense depreciable cost computing module B8; Operation expense computing module B6, accident risk pricing module B7, broad sense depreciable cost computing module B8 are connected with the total cost computing module B5 under Replacing Scheme respectively; Total cost computing module B5 under Replacing Scheme, power supply income calculation module B3 are connected with average annual net proceeds computing module B4 respectively;

Average annual net proceeds computing module A4, average annual net proceeds computing module B4 are connected with data fitting comparative analysis module 6 respectively.

2. the using method of a kind of transformer economy life predication apparatus according to claim 1, is characterized in that:

Input parameter receives/delivers input parameter Auto-matching that user inputs by module (1) and is delivered to equivalent time expand computing module (A2/B2) in process computation module (2) respectively, probability of malfunction function computation module (A1/B1), under overhauling model (22) and replacing model (21), then undertaken alternately by constant interactive module (5) and constant storehouse (4), obtain the constant value of modules and submodule calculating needs thereof, after calculating according to the computation model of modules and submodule thereof, export maintenance model (22) and the average annual net proceeds under changing model (21) respectively, finally by data fitting comparative analysis module (6), maintenance model and the average annual net proceeds changed under model are carried out curve fitting, solve the intersection point obtaining two curves, this intersection value is the transformer current economy life-span,

The computation model of described modules and submodule thereof is:

(1) probability of malfunction function computation module

Failure rate function λ (t): $\mathrm{\λ}\left(t\right)=\frac{m}{\mathrm{\η}}{\left(\frac{t+\mathrm{\Δs}}{\mathrm{\η}}\right)}^{m-1};$

Current time trouble shooting rate fall Δ λ (t):

Parameter Δ s1: ${\mathrm{\Δs}}_1=\mathrm{\η}\sqrt[m-1]{\mathrm{\λ}\frac{\mathrm{\η}}{m}}-t_0;$

Equivalence enlistment age parameter Δ s:

(2) equivalence time expand computing module

Equivalence time expand Δ q (t): $\mathrm{\Δq}\left(t\right)=\mathrm{\η}\sqrt[m-1]{\mathrm{\λ}\left(t\right)\frac{\mathrm{\η}}{m}}-\mathrm{\η}\sqrt[m-1]{[\mathrm{\λ}\left(t\right)-\mathrm{\Δ\λ}\left(t\right)]\frac{\mathrm{\η}}{m}};$

(3) model is overhauled

1) power supply income calculation module

Power supply income I under maintenance model _p1: I _p1=ξ S η Δ p [t+ Δ q (t)-t ₀];

2) operation expense computing module

Operation expense CO ₁=CO _e1+ CO _m1;

CO can be expended _e1: CO _e1=(P ₀+ η ²p _k) p ₁μ [t+ Δ q (t)-t ₀] 8760;

Operation and maintenance cost CO _m1: ${\mathrm{CO}}_{\mathrm{ml}}={\mathrm{CO}}_b{\∫}_{t_0}^{t+\mathrm{\Δq}\left(t\right)}(1+{\mathrm{\α}}_{1}t)\mathrm{dt};$

3) accident risk pricing module

Accident risk cost CR ₁: ${\mathrm{CR}}_1[{\∫}_{t_0}^t\mathrm{\λ}\left(t\right)\mathrm{dt}+{\∫}_{t-\mathrm{\Δt}}^t\mathrm{\λ}\left(t\right)\mathrm{dt}]\mathrm{LOTF},$ Qi Zhong ⊿ t=⊿ q;

Economic loss LOTF:LOTF=Loss after transformer breaks down ₁+ Loss ₂+ Loss ₃+ Loss ₄;

System cutting load cost Loss ₁:

The correction factor β 1: β of system risk ₁=β ₁₁× β ₁₂× β ₁₃;

Mean failure rate cost Loss ₂: Loss ₂=C _f× β ₂;

The correction factor β of rehabilitation cost ₂: β ₂=β ₂₁× β ₂₂;

Personnel risk cost Loss ₃:

Environmental costs Loss ₄for constant;

4) broad sense depreciable cost computing module

Broad sense depreciable cost CD ₁: ${\mathrm{CD}}_1=(\mathrm{CI}+\mathrm{CD}+C_{\mathrm{rc}})\frac{t-t_0}{T_{\mathrm{dl}}};$

Transformer initial outlay cost CI:CI=CI _e+ CI _i+ CI _o;

The retired cost CD:CD=CD of transformer _t-CD _r;

Retired handling CD _t: CD _t=CI _dcC _r;

Residual value CD when equipment is retired _r: CD _r=CI _ecca;

The loss of outage Crc of new and old transformer equipment handing-over is constant;

5) calculation of maintenance cost module

Cost of overhaul CM1:CM ₁=CM _t+ CM _r;

Recondition expense CM _t: CM _t=(1+ α ₂t) C _b;

Shutdown loss cost CM _r: CM _r=t _rsc _rb;

Electrical network faces shutdown risk cost C per hour because redundance declines _rb: C _rb=S Δ p α _c;

Repair time t _rs: t _rs=t _b+ α ₃t;

6) the total cost computing module under maintenance solution

Total cost C under maintenance solution ₁: C ₁=CO ₁+ CR ₁+ CD ₁+ CM ₁;

7) average annual net proceeds computing module

Average annual net proceeds W ₁: $W_1=\frac{I_{P1}-C_1}{t+\mathrm{\Δq}\left(t\right)-t_0};$

(4) model is changed

1) power supply income calculation module

Power supply income I _p2: I _p2=ξ S η Δ p (t-t ₀);

2) operation expense computing module

Operation expense CO ₂: with the operation expense computing module of maintenance model;

3) accident risk pricing module

Accident risk cost CR ₂: with the accident risk pricing module of maintenance model;

4) broad sense depreciable cost computing module

Broad sense depreciable cost CD ₂: with the broad sense depreciable cost computing module of maintenance model;

5) the total cost computing module under Replacing Scheme

Total cost C under Replacing Scheme ₂: C ₂=CO ₂+ CR ₂+ CD ₂;

6) average annual net proceeds computing module

Average annual net proceeds W2:

(5) calculating in economy life-span

Maintenance and average annual net proceeds W1 and the W2 changed under model are carried out curve fitting by data fitting comparative analysis module by the calculating in transformer economy life-span, and the intersection point of two curves is this transformer current economy life-span.