CN106680627A - Method for determining transformer winding time constant on the condition of different load coefficients - Google Patents

Abstract

The invention discloses a method for determining a transformer winding time constant on the condition of different load coefficients. The method comprises the following steps of acquiring a transformer-related thermal coefficient, acquiring rated top-layer winding time constants (tauw, R) through fitting change between a hot point temperature and a top-layer oil temperature, and finally solving the winding time constant tauw through introducing relative winding time constants (tauw, pu). The method fills a gap in calculating the winding time constant on the condition of different loads and furthermore has advantages of simple calculation mode and easy acquisition of required information. Furthermore the method can lay a foundation for calculating dynamic change of the hot point temperature.

Description

A kind of method for determining Transformer Winding time constant under different loads coefficient

Technical field

The present invention relates to a kind of computational methods, and in particular to the Transformer Winding time is normal under one kind determination different loads coefficient Several methods, the technology is used for the dynamic change of calculating transformer winding time constant.

Background technology

Oil-filled transformer is the nucleus equipment of electrical power trans mission/distribution system, and its life-span management and optimization design have obtained extensive pass Note, it is also to assess the major parameter of transformer insulated life loss that temperature rise of hot spot is the principal element of restriction transformer station high-voltage side bus, because This research hot-spot temperature of transformer is particularly significant.

In Practical Project, hot(test)-spot temperature is calculated and typically adopt two-part Temperature Rise Model, i.e.,：Top layer oil phase is for environment temperature Liter, focus are relative to top-oil temperature liter；Wherein, Transformer Winding time constant describes focus and rises change soon with respect to top-oil temperature Slowly.In order to obtain the solution mode that rated transformer winding time constant, IEC directive/guides, IEEE directive/guides etc. give rated value. In actual motion, Transformer Winding time constant can be with load factor (load current), transformator top-oil temperature degree, transformer oil Viscosity, the change of transformer oil flow velocity and change.IEC directive/guides, IEEE directive/guides and related scholar once have studied transformer oil and glued Impact of the degree to Transformer Winding time constant.However, load factor (load current) is used as maximum factor is affected, it is to becoming The quantitative description that depressor winding time constant affects but does not have research.Therefore it is badly in need of becoming under a kind of determination different loads coefficient of research The method of depressor winding time constant, so as to quantify impact of the load factor (load current) to Transformer Winding time constant.

The content of the invention

In view of this, it is an object of the invention to provide a kind of determine Transformer Winding time constant under different loads coefficient Method, quantifies variation relation of the Transformer Winding time constant with load factor (load current).

Technical proposal that the invention solves the above-mentioned problems is：

The first step, obtains transformator relevant parameter, including Transformer Winding index y, and specified focus is with respect to top-oil temperature liter Δθ_hs,R, specified focus is with respect to top-oil temperature liter Δ θ_hs,R。

Second step, applying nominal load to transformator makes its cold start-up, and records time dependent top-oil temperature θ_oilAnd Hot(test)-spot temperature θ_hs, nominal load made hot(test)-spot temperature θ action time no less than 12 hours_hsRise and tend towards stability, and utilize following formula It is fitted to obtain rated transformer winding timeconstantτ_w,R

Δθ_hs=θ_hs-θ_oil (1)

In formula, Δ θ_hsIt is focus with respect to top-oil temperature liter.

3rd step, using following formula Transformer Winding time constant under different loads is calculated：

τ_w,pu=K^y-2 (3)

τ_w=τ_w,R×τ_w,pu (4)

In formula, τ_wIt is the Transformer Winding time constant under required different loads coefficient, τ_w,puUnder being description arbitrary load The relative Transformer Winding time constant of Transformer Winding time constant and rated transformer winding time constant relation, K is negative Carry coefficient；Transformer Winding index y should choose different value according to different transformer types and radiating mode, and distribution transformer y takes 1.6, ONAN/ONAF/OF type transformer y take 1.3, OD type transformer y and take 1.

The computational methods of Transformer Winding time constant under different loads coefficient of the present invention, with advantages below：

1) the Transformer Winding time constant under different loads coefficient can be obtained, compared to changeless rated transformer Winding time constant, it preferably reflects the actual dynamic change of Transformer Winding time constant；

2) Transformer Winding time constant under different loads coefficient calculates easy, is dispatched from the factory parameter by conventional transformator The winding time constant variation relation of institute's research transformator can be calculated；

3) compared to the recommendation and computing formula of rated value, at rated loads in long-time Cold Start, note Record hot(test)-spot temperature, top-oil temperature are more accurate to be fitted rated transformer winding time constant.

Description of the drawings

Fig. 1 be transformator at rated loads cold start-up when focus with respect to top-oil temperature liter；

Fig. 2 is the ratio of Transformer Winding time constant and rated transformer winding time constant under different loads, Yi Jixiang Constant, τ between transformer oil winding_w,pu；

Transformer Winding time constant under Fig. 3 different loads.

Specific embodiment

Below in conjunction with the accompanying drawings the present invention is further described with specific implementation process.It is emphasized that this place What is described is embodied as case only to explain patent of the present invention, is not intended to limit the present invention inventional idea and its right will The scope asked.

The first step, obtains transformator relevant parameter, including Transformer Winding index y, and specified focus is with respect to top-oil temperature liter Δθ_hs,R.Table 1 is the above parameter of certain transformator.

Table 1

Second step, applying nominal load to transformator makes its cold start-up, and records time dependent top-oil temperature θ_oilAnd Hot(test)-spot temperature θ_hs, nominal load made hot(test)-spot temperature θ action time no less than 12 hours_hsRise and tend towards stability, and utilize following formula It is fitted to obtain rated transformer winding timeconstantτ_w,R

Δθ_hs=θ_hs-θ_oil (5)

In formula, Δ θ_hsIt is focus with respect to top-oil temperature liter.

By the fitting to Fig. 1 data, formula (6) can be specially：

So as to τ_w,RIt is defined as 3086s.

3rd step, using following formula Transformer Winding time constant under different loads is calculated：

τ_w,pu=K^y-2 (8)

τ_w=τ_w,R×τ_w,pu (9)

In formula, τ_wIt is the Transformer Winding time constant under required different loads coefficient, τ_w,puUnder being description arbitrary load The relative Transformer Winding time constant of Transformer Winding time constant and rated transformer winding time constant relation, K is negative Carry coefficient；Transformer Winding index y should choose different value according to different transformer types and radiating mode, and distribution transformer y takes 1.6, ONAN/ONAF/OF type transformer y take 1.3, OD type transformer y and take 1.So as to formula (8), formula (9) are what is studied Can be identified as under particular transformer：

τ_w,pu=K^-0.7 (10)

τ_w=τ_w,R×τ_w,pu=3086 × K^-0.7 (11)

τ_w,puAs shown in Fig. 2 required Transformer Winding timeconstantτ_wRelation with load factor is as shown in Figure 3.

Claims (2)

1. it is a kind of determine different loads coefficient under Transformer Winding time constant method, by the Transformer Winding under nominal load Time constant expand to arbitrary load to adapt to different loads coefficient under Transformer Winding time constant change, it is characterised in that The method is comprised the following steps：

The first step, obtains transformator relevant parameter, including Transformer Winding index y, and specified focus rises Δ with respect to top-oil temperature θ_hs,R；

Second step, applying nominal load to transformator makes its cold start-up, and records time dependent top-oil temperature θ_oilAnd focus Temperature θ_hs, nominal load made hot(test)-spot temperature θ action time no less than 12 hours_hsRise and tend towards stability, and be fitted using following formula Obtain rated transformer winding timeconstantτ_w,R,

Δθ_hs=θ_hs-θ_oil

${\mathrm{\Δ\θ}}_{hs}={\mathrm{\Δ\θ}}_{hs,R}\×(1-e^{-\frac{t}{{\mathrm{\τ}}_{w,R}}})$

In formula, Δ θ_hsIt is focus with respect to top-oil temperature liter；

3rd step, using following formula Transformer Winding time constant under different loads is calculated：

τ_w,pu=K^y-2

τ_w=τ_w,R×τ_w,pu

In formula, τ_wIt is the Transformer Winding time constant under required different loads coefficient, τ_w,puIt is description arbitrary load transformator The relative Transformer Winding time constant of winding time constant and rated transformer winding time constant relation, K is load factor.

2. under different loads coefficient according to claim 1 Transformer Winding time constant computational methods, its feature exists Different value should be chosen according to different transformer types and radiating mode in Transformer Winding index y, distribution transformer y takes 1.6, ONAN/ONAF/OF type transformer y take 1.3, OD type transformer y and take 1.