CN108897923A - A kind of method of determining tractive transformer around class index - Google Patents

Abstract

The invention discloses a kind of determining tractive transformers around the method for class index, includes the following steps：It obtains tractive transformer related property parameter, quantitatively, according to related datas such as winding average temperature rising and load coefficients carry out recurrence calculating to around class index using winding exponential analytic model by the waiting of winding area thermal model calculating winding average temperature rising.Compared to the reference value that ieee standard is recommended, the method for the present invention quick estimation calculated that tractive transformer temperature rise of hot spot under more times of overloads is more suitable for around class index facilitates under wide in range load section more accurately to illustrate its temperature rise change.

Description

A kind of method of determining tractive transformer around class index

Technical field

The present invention relates to electric insulation on-line checking and fault diagnosis field, especially a kind of determining tractive transformer winding The method of index.

Background technique

Core equipment of the tractive transformer as high-speed railway tractive power supply system, highly effective and safe run the fortune to high-speed rail Battalion's development plays a crucial role.The working life of tractive transformer depends on built-in electrical insulation performance, and heat ageing is it The major influence factors of insulation performance deterioration, therefore the working life of tractive transformer and its internal temperature rise are closely bound up.

It include at present that top-oil temperature rises and the general means of determination of temperature rise of hot spot are bases to inside transformer temperature rise In IEEE and IEC standard " two-part " temperature rise calculation formula carry out, but should " two-part " Temperature Rise Model be primarily adapted for use in through Often general oil-immersed power transformer of the work under rated condition.For tractive transformer, due to the spy in train operation Different operating condition causes tractive transformer operating load to have the characteristics that amplitude abrupt change, constant interval are wide in range and fluctuation is larger, this will The calculating error for directly resulting in " two-part " Temperature Rise Model increases, and declines to the monitoring accuracy of tractive transformer internal temperature.

Summary of the invention

The purpose of the present invention is to propose to a kind of determining tractive transformers around the method for class index, and this method considers transformer Around calculated value of the class index under more times of overloads so that its be more suitable for having the tractive transformer in wide in range load section around The calculating of group temperature rise of hot spot.

Realize that the technical solution of the object of the invention is as follows：

A kind of determining tractive transformer around class index method, including

Step 1：The average temperature gradient g computation model for enabling the tractive transformer winding is：

In formula, g_rFor winding average temperature gradient under nominal load；M is around class index, for describing winding mean temperature Gradient with load variation tendency；I_puFor load factor, T_wFor winding mean temperature, T_to_pFor top-oil temperature, T_bo_mFor bottom Oil temperature；

Step 2：Regression estimates are carried out to winding exponent m using double-log linear regression model (LRM), it is as follows：

ln(g/g_r)=2mln (I_pu)

In formula, Y=ln (g/g is enabled_r), X=ln (I_pu)；

Using least squares identification parameter m, i.e.,：

In formula,J is number of samples, and i is label；

Wherein, the winding mean temperature T_w, top-oil temperature T_topWith bottom oil temperature T_bomAcquiring method, including

Step 1：Obtain the tractive transformer structure transitivity parameter, including Cool Hot Core high potential difference Δ h, winding height h_w, radiator height h_r, the vertical oil duct thermal-hydraulic diameter D of winding_w, radiator oil duct thermal-hydraulic diameter D_r, oily specific heat capacity c_oil, air specific heat capacity c_air, oil density ρ_oil, atmospheric density ρ_air, oily thermal expansion coefficient β_oil, winding frictional resistant coefficient f_w、 Radiator frictional resistant coefficient f_r, radiator overall heat-transfer coefficient U, winding surface coefficient of heat transfer u_w, winding area circulation area A_w、 Radiator circulation area A_r, the effective heat dissipation area A of radiator_R, winding and oil stream circumferencial direction contact surface area A_s, temperature difference index λ, environment temperature T_amb；

Step 2：Simultaneous following formula and condition iteratively solve winding area oil stream volume using Newton-Raphson method Flow G_w, radiator oil stream volume flow G_r, top-oil temperature T_top, bottom oil temperature T_bomWith winding mean temperature T_w；The traction Inside transformer is single cycle, G_w=G_r；

1) thermal buoyancy effect under limit in the vertical oil duct of winding and fluid resistance reach balance, as follows：

In formula, g_aFor acceleration of gravity, S is cooling cycle area,

S=Δ h (T_top-T_bom)+h_r[T_top-T_bom-ΔT_lm-0.5(T_top-T_amb)],

Wherein, Δ T_lmFor the logarithmic mean temperature difference (LMTD) of oil stream in radiator and outside air,

2) winding generates load loss Q when stable state_wEqual to the heat that oil stream around it absorbs, i.e.,

Q_w=ρ_oilc_oilG_w(T_top-T_bom)；

3) along the heat of the outside Convention diffusion in its surface, i.e., the heat that oil stream absorbs around winding is equal to coil

4) oil circulation reaches final stable state, in radiator oily relative atmospheric temperature rise be

T_oil-T_air=Ce^-λh,

In formula, T_oil、T_airRespectively along the oil stream temperature and air themperature of radiator short transverse h；C be bottom oil temperature and The difference of environment temperature；

Winding load loss Q_wThe heat of generation will all be transmitted to outside air by oil stream, i.e.,

Q_w=UA_R(T_oil-T_air)=UA_RCe^-λh；

Wherein,Q_w,RIt is lost for the nominal load of the tractive transformer；

5) environment temperature when normal atmosphere pressure tractive transformer operation is selected as reference temperature.

The beneficial effects of the present invention are propose a kind of more times of tractive transformer based on double-log linear regression function Winding index Analytic Calculation Method under overload calculates gained and is more suitable for the traction with wide in range load section around class index The calculating of coiling hot point of transformer temperature rise, compared to the reference value that ieee standard is recommended, this method improves coiling hotspot temperature The computational accuracy risen, has the following advantages that：

1) it when obtaining tractive transformer winding average temperature data, is based primarily upon the conservation of energy and the conservation of momentum is counted It calculates, the limitation of non-loaded coefficient；

2) more times of load sections be can choose around the calculating of class index, it is contemplated that the traction voltage transformation with wide in range part throttle characteristics The special operation condition of device, compared to general power transformer, value is more suitable for the coiling hotspot temperature rise meter of tractive transformer It calculates；

3) the winding index that this method can be used for the tractive transformer of different structure calculates, and has certain universality.

Detailed description of the invention

Fig. 1 is flow chart of the invention.

Specific embodiment

Invention is further explained below.

Tractive transformer dependency structure transitivity parameter known to the first step, acquisition：

Cool Hot Core high potential difference Δ h, winding height h_w, radiator height h_r, the vertical oil duct thermal-hydraulic diameter D of winding_w, dissipate Hot device oil duct thermal-hydraulic diameter D_r, oily specific heat capacity c_oil, air specific heat capacity c_air, oil density ρ_oil, atmospheric density ρ_air, oil heat Coefficient of expansion β_oil, winding frictional resistant coefficient f_w, radiator frictional resistant coefficient f_r, radiator overall heat-transfer coefficient U, winding table Face heat transfer coefficient u_w, winding area circulation area A_w, radiator circulation area A_r, the effective heat dissipation area A of radiator_R, winding with Oil stream circumferencial direction contact surface area A_s, temperature difference index λ, environment temperature T_amb。

Second step solves unknown quantity undetermined, including：Winding area oil stream volume flow G_w, radiator oil stream volume flow G_r, top-oil temperature T_top, bottom oil temperature T_bom, winding mean temperature T_w, as follows：

1) thermal buoyancy effect under limit in the vertical oil duct of winding and fluid resistance reach balance, as shown in formula：

In formula, g_aFor acceleration of gravity, S is cooling cycle area, is defined as follows：

S=Δ h (T_top-T_bom)+h_r[T_top-T_bom-ΔT_lm-0.5(T_top-T_amb)] (2)

In formula, Δ T_lmFor the logarithmic mean temperature difference (LMTD) of oil stream in radiator and outside air, it is defined as：

When inside transformer is single cycle, relational expression G_w=G_rIt sets up；

2) winding generates load loss Q when stable state_wEqual to the heat that oil stream oil stream around it absorbs, i.e.,：

Q_w=ρ_oilc_oilG_w(T_top-T_bom) (4)

3) heat that oil stream absorbs around winding is equal to coil along the heat of the outside Convention diffusion in its surface：

4) oil circulation reaches final stable state, oily relative atmospheric temperature rise in radiator：

T_oil-T_air=Ce^-λh (6)

In formula, T_oil、T_airRespectively along the oil stream temperature and air themperature of radiator short transverse h；C be bottom oil temperature and Environment temperature difference；

The heat that winding loss generates will all be transmitted to outside air by oil stream：

Q_w=UA_R(T_oil-T_air)=UA_RCe^-λh (7)

5) environment temperature when normal atmosphere pressure tractive transformer operation is selected as reference temperature；

To sum up, in conjunction with first step known parameters, simultaneous 1) to 5) in formula and condition, utilize Newton- Raphson method (Newton-Raphson method) iteratively solves unknown quantity：G_w、G_r、T_top、T_bom、T_w；Simultaneously as winding loss with Q is lost in nominal load_w,RAnd load factor I_puThere are following relationships：

It therefore, can be according to load factor I_puCalculate corresponding load loss, so solve under the load it is above-mentioned to Solve parameter.

Third step lists winding average temperature gradient g computation model：

In formula, g_rFor winding average temperature gradient under nominal load；M is around class index, for describing winding mean temperature Gradient with load variation tendency；

Regression estimates are carried out to winding exponent m using double-log linear regression model (LRM), are shown below：

ln(g/g_r)=2mln (I_pu) (10)

In formula, Y=ln (g/g is enabled_r), X=ln (I_pu).Using least squares identification parameter m, i.e.,：

In formula,J is number of samples, and i is label；

Second step winding average temperature data calculated and load factor are substituted into the recurrence mould in third step by the 4th step Type finds out winding exponent m.

Claims (1)

1. a kind of determining tractive transformer is around the method for class index, which is characterized in that including

Step 1：The average temperature gradient g computation model for enabling the tractive transformer winding is：

In formula, g_rFor winding average temperature gradient under nominal load；M be around class index, for describe winding average temperature gradient with The variation tendency of load；I_puFor load factor, T_wFor winding mean temperature, T_topFor top-oil temperature, T_bomFor bottom oil temperature；

Step 2：Regression estimates are carried out to winding exponent m using double-log linear regression model (LRM), it is as follows：

ln(g/g_r)=2mln (I_pu)

In formula, Y=ln (g/g is enabled_r), X=ln (I_pu)；

Using least squares identification parameter m, i.e.,：

In formula,J is number of samples, and i is label；

The winding mean temperature T_w, top-oil temperature T_to_pWith bottom oil temperature T_bo_mAcquiring method, including

Step 1：Obtain the tractive transformer structure transitivity parameter, including Cool Hot Core high potential difference Δ h, winding height h_w, heat dissipation Device height h_r, the vertical oil duct thermal-hydraulic diameter D of winding_w, radiator oil duct thermal-hydraulic diameter D_r, oily specific heat capacity co_il, air Specific heat capacity c_air, oil density ρ o_il, atmospheric density ρ_air, oil thermal expansion coefficient β o_il, winding frictional resistant coefficient f_w, radiator is along journey Resistance coefficient f_r, radiator overall heat-transfer coefficient U, winding surface coefficient of heat transfer u_w, winding area circulation area A_w, radiator circulation Area A_r, the effective heat dissipation area A of radiator_R, winding and oil stream circumferencial direction contact surface area A_s, temperature difference index λ, environment temperature T_amb；

Step 2：Simultaneous following formula and condition iteratively solve winding area oil stream volume flow using Newton-Raphson method G_w, radiator oil stream volume flow G_r, top-oil temperature T_to_p, bottom oil temperature T_bo_mWith winding mean temperature T_w；The traction voltage transformation It is single cycle, G inside device_w=G_r；

1) thermal buoyancy effect under limit in the vertical oil duct of winding and fluid resistance reach balance, as follows：

In formula, g_aFor acceleration of gravity, S is cooling cycle area,

S=Δ h (T_top-T_bom)+h_r[T_top-T_bom-ΔT_lm-0.5(T_top-T_amb)],

Wherein, Δ T_lmFor the logarithmic mean temperature difference (LMTD) of oil stream in radiator and outside air,

2) winding generates load loss Q when stable state_wEqual to the heat that oil stream around it absorbs, i.e.,

Q_w=ρ_oilc_oilG_w(T_top-T_bom)；

3) along the heat of the outside Convention diffusion in its surface, i.e., the heat that oil stream absorbs around winding is equal to coil

4) oil circulation reaches final stable state, in radiator oily relative atmospheric temperature rise be

T_oil-T_air=Ce^-λh,

In formula, T_oil、T_airRespectively along the oil stream temperature and air themperature of radiator short transverse h；C is bottom oil benign environment The difference of temperature；

Winding load loss Q_wThe heat of generation will all be transmitted to outside air by oil stream, i.e.,

Q_w=UA_R(T_oil-T_air)=UA_RCe^-λh；

Wherein,Q_w,RIt is lost for the nominal load of the tractive transformer；

5) environment temperature when normal atmosphere pressure tractive transformer operation is selected as reference temperature.