CN104657599A - Single-phase transformer model for calculating direct current magnetic bias through equivalent differential electric/magnetic path principle - Google Patents

Abstract

The invention discloses a single-phase transformer model for calculating direct current magnetic bias through an equivalent differential electric/magnetic path principle. The single-phase transformer model is implemented through the following steps: a, establishing a circuit model based on a single-phase transformer iron core topological structure and transformer parameters; b, establishing a differential magnetic path model based on a differential magnetic path principle; c, deriving a relational expression among an iron core differential magnetic flux, a differential magnetomotive force, a magnetic chain and a loop differential magnetic flux based on a transformer differential magnetic path model; d, deriving a differential inductance matrix based on conclusions obtained by the steps a, b and c; e, establishing a single-phase transformer group circuit model based on a single-phase transformer winding connecting form and a differential pole matrix; f, solving a transformer differential circuit equation group based on a numerical algorithm, and solving a target variable; g, verifying the credibility of the model. According to the single-phase transformer model, the distortion degree of transformer excitation current and primary and secondary winding current during the invasion of different direct current quantities can be accurately obtained, the safe operation of an alternating current-direct current hybrid power grid is ensured, and the economic rationality of equipment selection is effectively guaranteed.

Description

Equivalence differential electricity (magnetic) road principle calculates DC magnetic biasing single transformer model

Technical field

The invention belongs to Transformer Modeling technical field, be specifically related to a kind of equivalent differential electricity (magnetic) road principle and calculate DC magnetic biasing single transformer model.

Background technology

China is vast in territory, and the distributed pole of power generation energy resource and power load is unbalanced, and primary energy base and power load center are in " contrary distribution ", and this objective reality determines the certainty of the trans-regional and extensive flowing of China's flow of power.D.C. high voltage transmission owing to having obvious technology economy advantage in remote, large capacity transmission and power system interconnection, the water power abundant in western part, regenerative resource and large moulded coal electricity high-level efficiency are sent in the process of Middle Eastern and play an important role, and therefore obtain Large-scale programming construction in China.

But when high-voltage dc transmission electric monopole ground return circuit is run, the powerful ground DC current that enters likely causes neutral grounded transformer generation DC magnetic biasing near direct current grounding pole, causes core sataration degree greatly to increase.The impact of DC magnetic biasing on transformer is mainly manifested in: on the one hand, non-linear due to static exciter characteristic, exciting current high distortion, and transformer reactive loss increases; On the other hand, core sataration makes leakage field increase, and associated components loss increases, and temperature rise increases, the safe and stable operation of serious threat AC-DC hybrid power grid.

For transformer DC magnetic bias, carried out many-sided research both at home and abroad, wherein DC magnetic biasing is the focus studied on the impact of transformer body and the impact of transformer on operation of power networks of generation DC magnetic biasing.The key of research the problems referred to above sets up suitable transformer model, can this is related to the accurately impact that brings transformer operation characteristic of researching DC electric current, also be related to can reasonable assessment DC magnetic biasing on the impact of electric power netting safe running, and can the rational DC magnetic biasing braking measure of selecting properly.

Be directed to this, have scholar to set up transformer circuit magnetic coupling model, describe the magnetization curve of transformer core with experimental formula, propose the non-linear magnetic resistance computing formula of frequency dependence of iron core, Modling model in frequency domain; There is scholar to establish transformer synthesis circuit model with the principle of duality, only use a circuit can represent the electromagnetic behavior of whole transformer, but be only applicable to the transformer with planar magnetic topological structure because duality is theoretical, which has limited the application of this model; Have scholar theoretical based on circuit and magnetic circuit, have under proposing DC magnetic biasing, the three-phase three-limb transformer model of transless fuel tank.

Existing model Problems existing can be summarized as 2 points: for the transformer having complicated magnetic structure, can not ensure precision or calculate loaded down with trivial details; Ensure that precision, but can only be applied on the simple transformer of structure.

Summary of the invention

The object of this invention is to provide a kind of single transformer model, in order to assess transformer tolerance DC magnetic biasing ability, solve that existing model is too complicated or precision is not high and can only the narrow shortcoming of range of application.

In order to solve the problem, adopted technical scheme is: a kind of equivalent differential electricity (magnetic) road principle calculates DC magnetic biasing single transformer model, comprises the following steps:

A. based on monophase transformer core topological structure and transformer parameter, circuit model is set up;

B. based on differential magnetic circuit principle, differential magnetic circuit model is set up;

C. based on transformer differential magnetic circuit model, derivation iron core differential magnetic flux, differential mmf, magnetic linkage and loop differential flux relationship formula;

D. based on first three steps conclusion, derivation differential inductance matrix;

E. connect form and differential electric pole matrix based on single transformer winding, set up Single Phase Transformer Set circuit model;

F. based on numerical algorithm, solve transformer differentiating circuit system of equations, ask for target variable;

G. model Trusting eBusiness.

Further preferred version: in step a, characterizes transformer core eddy current loss by non-linear resistance.

Further preferred version: in step b, based on single transformer parameter, sets up transformer differential magnetic circuit model.

Further preferred version: in step f, uses Matlab software simulating numerical algorithm, obtains that the exciting current of transformer when normal operating conditions and DC magnetic biasing, magnetic are close, magnetic field intensity.

Advantage of the present invention: when to single transformer modeling, have employed more reasonably physical model, iron core B-H loop, iron core magnetic hysteresis and the key element such as turbine effect, iron core topological structure are considered, utilize equivalent differential electricity (magnetic) road (Equivalent Incremental Circuit, EIC) transformer circuit, flux coupled equation is built, efficiently solve the contradiction that transformer model precision and complexity can not get both, for transformer DC magnetic bias research provides a kind of accurate and practical physical model.

According to the single transformer model that the present invention proposes, accurately can obtain transformer magnetizing current and first and second winding current distortion degree when different DC amount is invaded, tolerate DC magnetic biasing ability for reliable assessment transformer and determine that effectively reasonably control measures provides foundation, guarantee the safe operation of AC-DC hybrid power grid, effectively can ensure the economic rationality of lectotype selection, to the rationality of lectotype selection and economy significant.

Accompanying drawing explanation

Fig. 1 is single-phase core type transformer model construction process flow diagram

Fig. 2 is transformer core lamination schematic diagram

Fig. 3 is transformer core equivalent magnetic branch road

Fig. 4 is core type transformer iron core equivalent magnetic circuit modeling

Fig. 5 is core type transformer iron core equivalent magnetic circuit modeling

Fig. 6 is single-phase three post double winding core type transformer core structure schematic diagram

Fig. 7 is transformer core magnetic branch road schematic diagram

Fig. 8 is transformer core lumped parameter equivalent magnetic branch road

Fig. 9 is transformer core differential equivalent magnetic branch road

Figure 10 is single-phase three post double winding core type transformer differential magnetic circuit models

Figure 11 is Y/Y tietransformer equivalent electrical circuit

Figure 12 is single-phase three post double winding core type transformer excitation surge currents

Embodiment

Below in conjunction with accompanying drawing, the present invention will be further described in detail.

1., based on monophase transformer core topological structure and transformer parameter, set up circuit model

(1) non-linear resistance characterizes transformer core eddy current loss

Transformer core magnetic flux constantly changes, and the magnetic field of change will induction electromotive force generation current in the core which, and these electric currents be that eddy current shape flows in inner loop unshakable in one's determination around magnetic flux, are called eddy current.Fig. 2 is core lamination stack schematic diagram, and core lamination stack length is l _p, thickness is d, and sectional area is A _p, τ is lamination width, and σ is conductivity, B _pfor magnetic induction density.

Theoretical according to Bertotti, core type transformer iron core instant power loss is:

$P_c=H_c\frac{\mathrm{dB}}{\mathrm{dt}}{A}_c{l}_c=\frac{\frac{{\mathrm{\σd}}^2{l}_c}{{12A}_c}+{\left(\frac{\mathrm{Gd\τ}{H}_0{\mathrm{\σl}}_c^2}{A_c}\right)}^{0.5}{\left(\frac{\mathrm{d\Φ}}{\mathrm{dt}}\right)}^{-0.5}}{N_1^2}{\left(N_1\frac{\mathrm{d\Φ}}{\mathrm{dt}}\right)}^2=\frac{k_c}{N_1^2}{\left(N_1\frac{\mathrm{d\Φ}}{\mathrm{dt}}\right)}^2---\left(1\right)$

In above formula, H _crepresent the magnetic field intensity current related with iron core vortex, dimensionless constant G=0.1356, H ₀relevant with the Inner gesture that core lamination stack neticdomain wall causes, general and maximum magnetic induction B _maxrelevant.N ₁d Φ/dt has the dimension of voltage, therefore there is the inverse of resistance dimension, i.e. Ω ^-1, iron core vortex loss can be characterized by:

$r_c=N_1^2/k_c---\left(2\right)$

When transformer differential magnetic circuit model is determined, iron core equivalence eddy current loss resistance r can be determined according to (2) formula _e.The magnetic potential that eddy current produces can be written as F _cp=H _cl _p, (1) is substituted into above formula, can obtain:

F _cp＝k _cp(dΦ _p/dt) (3)

Therefore, in Fig. 2, lamination eddy effect can use mmf F _cp, magnetic resistance R _mp, magnetic flux Φ _pseries equivalent magnetic branch road represents, as shown in Figure 3.If iron core is formed by n laminates closed assembly, according to individual layer lamination equivalent magnetic circuit modeling, the equivalent magnetic circuit modeling of the core type transformer that n laminates is formed can be obtained, as shown in Figure 4.If all laminations are identical, Φ can be obtained by Fig. 4 _i=Φ _i+1=Φ/n, A _ci=A _ci+1=A _c/ n, k _ci=k _ci+1=k _c, F _ci=F _ci+1=F _c, R _mi=R _mi+1, μ _mi=μ _mi+1.Can obtain according to Ampère circuital theorem:

f _i＝f _i+1(4)

Therefore, Fig. 4 magnetic circuit model can be equivalent to former limit mmf, secondary mmf and iron core vortex mmf further and connect with magnetic resistance unshakable in one's determination, as shown in Figure 5.Former and deputy limit winding current and the coefficient mmf of iron core vortex electric current are:

$F=N_i{i}_1-N_2{i}_2-k_c\frac{\mathrm{d\Φ}}{\mathrm{dt}}=N_1[i_1-\frac{k_c}{N_1^2}\left(N_1\frac{\mathrm{d\Φ}}{\mathrm{dt}}\right)]-N_2{i}_2=N_1{i}_1^{\′}-N_2{i}_2---\left(5\right)$

(5) formula illustrates, the eddy current loss of iron core can represent with a non-linear resistance with former limit winding parallel, wherein, according to different transformer core forms and magnetic circuit model, Eddy Current Loss In Core of An Electromagnetic resistance r can be obtained _c.

(2) single transformer circuit model

To any single transformer, A _ci, L _cifor area of core section, core length, Np, NsN _p, N _sfor former and deputy limit umber of turn, i _p, i _si is former and deputy limit winding current, Φ _ifor magnetic flux unshakable in one's determination, r _p, r _sbe respectively former and deputy limit winding resistance, r _cfor iron core vortex loss resistance, L _p, L _sbe respectively former and deputy limit winding inductance.

According to deriving above, single transformer former limit circuit model can be expressed as r _cwith r _pthe form that in parallel, other parameters are connected, secondary circuit model can be expressed as the form of the series connection between each parameter, and for single-phase three-column transformer, its circuit model can be as shown in Figure 6.

2., based on differential magnetic circuit principle, set up differential magnetic circuit model

(1) differential magnetic circuit principle

In Fig. 7, A _cifor core section amasss, L _cifor core length, N is umber of turn, _ifor winding current, Φ _ifor magnetic flux unshakable in one's determination; In Fig. 8, f _rmifor the magnetic pressure on magnetic resistance is fallen, R _mifor equivalent magnetic resistance unshakable in one's determination, F is mmf, Φ _ifor magnetic flux, f _ifor branch road magnetic pressure.Can obtain:

$\left\{\begin{array}{c}{f}_i=R_{\mathrm{mi}}{\mathrm{\Φ}}_i-F\\ R_{\mathrm{mi}}{\mathrm{\Φ}}_i=H_i{l}_{\mathrm{ci}}\end{array}\right.---\left(6\right)$

Above formula two ends, to time t differentiate, obtain:

$\left\{\begin{array}{c}{\mathrm{df}}_i/\mathrm{dt}=d\left(R_{\mathrm{mi}}{\mathrm{\Φ}}_i\right)/\mathrm{dt}-\mathrm{dF}/\mathrm{dt}=R_{\mathrm{mdi}}({\mathrm{d\Φ}}_i/\mathrm{dt})-\mathrm{dF}/\mathrm{dt}\\ d\left(R_{\mathrm{mi}}{\mathrm{\Φ}}_i\right)/\mathrm{dt}=d\left(H_i{l}_{\mathrm{ci}}\right)/\mathrm{dt}=l_{\mathrm{ci}}{\mathrm{dH}}_i/\mathrm{dt}=l_{\mathrm{ci}}({\mathrm{dH}}_i/{\mathrm{dB}}_i)({\mathrm{dB}}_i/\mathrm{dt})\\ =l_{\mathrm{ci}}/A_{\mathrm{ci}}({\mathrm{dH}}_i/{\mathrm{dB}}_i)({\mathrm{d\Φ}}_i/\mathrm{dt})=l_{\mathrm{ci}}/\left(A_{\mathrm{ci}}{\mathrm{\μ}}_{\mathrm{di}}\right)({\mathrm{d\Φ}}_i/\mathrm{dt})=R_{\mathrm{mdi}}({\mathrm{d\Φ}}_i/\mathrm{dt})\end{array}\right.---\left(7\right)$

Wherein, differential permeability μ _di=dB _i/ dH _i, differential magnetic resistance R _mdi=l _ci/ (μ _dia _ci).(7) formula first the Representation Equation branch road magnetic pressure, branch road magnetic flux, mmf rate of change relation, i.e. differential magnetic circuit principle, as shown in Figure 9.

(2) based on single transformer parameter, transformer differential magnetic circuit model is set up

For the single transformer of arbitrary form, based on EIC principle, differential magnetic circuit model can be set up.

For single-phase three-column transformer, its circuit model can be as shown in Figure 10.Wherein R _md1, R _md2, R _md3, R _md4, R _md5, R _md6for iron core, iron yoke differential magnetic resistance, differential magnetic flux is respectively d Φ ₁/ dt, d Φ ₂/ dt, d Φ ₃/ dt, R _ma, R _mao, R _mofor differential leakage flux between winding, corresponding differential leakage flux is respectively d Φ _ma/ dt, d Φ _ma0/ dt, Φ _m0/ dt, dF _p/ dt, dF _s/ dt is respectively former and deputy limit differential mmf.

Wherein, differential magnetic resistance is asked for by iron core monodrome magnetization curve or Jiles-Atherton model.For monodrome magnetization curve B=f (H), its differential permeability can be expressed as:

μ _di＝dB/dH＝d(f(H))/dH (8)

For Jiles-Atherton Model B=μ ₀(H+M), its differential permeability can be expressed as:

μ _di＝μ ₀(1+dM _irri/dH _i+dM _revi/dH _i) (9)

Wherein

$\left\{\begin{array}{c}\frac{{\mathrm{dM}}_{\mathrm{irri}}}{{\mathrm{dH}}_i}=\frac{M_{\mathrm{ani}}-M_{\mathrm{irri}}}{\mathrm{k\δ}-a_1(M_{\mathrm{ani}}-M_{\mathrm{irri}})}\\ \frac{{\mathrm{dM}}_{\mathrm{revi}}}{{\mathrm{dH}}_i}=c(\frac{{\mathrm{dm}}_{\mathrm{ani}}}{{\mathrm{dH}}_i}-\frac{{\mathrm{dM}}_{\mathrm{irri}}}{{\mathrm{dH}}_i})\\ M_{\mathrm{an}}\left(H\right)=M_s[\coth \left(\frac{H+{\mathrm{\α}}_{1}M}{{\mathrm{\α}}_2}\right)-\frac{{\mathrm{\α}}_2}{H+{\mathrm{\α}}_{1}M}]\\ \mathrm{\δ}=\mathrm{sign}(\mathrm{dH}/\mathrm{dt})\end{array}\right.---\left(10\right)$

M _anthe anhysteretic magnetization, M _ssaturation magnetization, α ₁mean-field parameter, α ₂statement anhysteretic magnetization curve shape, k reflects that magnetic domain is to motion restraining function, c reversible magnetization coefficient, 0 < c < 1.

3. based on differential magnetic circuit model, derivation iron core differential magnetic flux, differential mmf, magnetic linkage and loop differential flux relationship formula

Based on single transformer differential magnetic circuit model, according to Kirchhoff's law, iron core differential magnetic flux, differential mmf and loop differential flux relationship formula can be obtained:

$\left\{\begin{array}{c}\mathrm{d\&Phi;}/\mathrm{dt}=C({\mathrm{d\&Phi;}}_{\mathrm{loop}}/\mathrm{dt})\\ R({\mathrm{d\&Phi;}}_{\mathrm{loop}}/\mathrm{dt})=\mathrm{dF}/\mathrm{dt}\end{array}\right.---\left(11\right)$

Based on single transformer differential magnetic circuit model, differential magnetic linkage matrix and loop differential magnetic flux matrix relationship formula:

dΨ/dt＝N _Ψ(dΦ/dt) (12)

Differential mmf matrix dF/dt and differential current matrix dI _ps/ dt relational expression:

dF/dt＝N _FdI _ps/dt (13)

For single-phase three post core type transformers, iron core differential magnetic flux, differential mmf and loop differential flux relationship formula are respectively such as formula 14-a, 14-b, 14-c, and differential mmf matrix and differential current matrix relationship formula are such as formula 14-d:

$\frac{d}{\mathrm{dt}}\left(\begin{array}{c}{\mathrm{\&Phi;}}_1\\ {\mathrm{\&Phi;}}_2\\ {\mathrm{\&Phi;}}_3\end{array}\right)=\left(\begin{array}{ccccc}-1& 1& 0& 0& 0\\ 1& 0& 0& 0& 0\\ 0& 0& 0& 0& -1\end{array}\right)\frac{d}{\mathrm{dt}}\left(\begin{array}{c}{\mathrm{\&Phi;}}_{11}\\ {\mathrm{\&Phi;}}_{12}\\ {\mathrm{\&Phi;}}_{13}\\ {\mathrm{\&Phi;}}_{14}\\ {\mathrm{\&Phi;}}_{15}\end{array}\right)---(14-a)$

$\left\{\begin{array}{c}(R_{\mathrm{md}2}+R_{\mathrm{md}1}){\mathrm{d\&Phi;}}_{11}/\mathrm{dt}-R_{\mathrm{md}1}{\mathrm{d\&Phi;}}_{12}/\mathrm{dt}=-{\mathrm{dF}}_p/\mathrm{dt}+{\mathrm{dF}}_s/\mathrm{dt}\\ (R_{\mathrm{md}1}+R_{\mathrm{ma}}){\mathrm{d\&Phi;}}_{12}/\mathrm{dt}-R_{\mathrm{md}1}{\mathrm{d\&Phi;}}_{11}/\mathrm{dt}-R_{\mathrm{ma}}{\mathrm{d\&Phi;}}_{13}/\mathrm{dt}=0\\ (R_{\mathrm{ma}}+R_{\mathrm{ma}0}){\mathrm{d\&Phi;}}_{13}/\mathrm{dt}-R_{\mathrm{ma}}{\mathrm{d\&Phi;}}_{12}/\mathrm{dt}-R_{\mathrm{ma}0}{\mathrm{d\&Phi;}}_{14}/\mathrm{dt}={\mathrm{dF}}_p/\mathrm{dt}\\ (R_{\mathrm{ma}0}+R_{m0}){\mathrm{d\&Phi;}}_{14}/\mathrm{dt}-R_{\mathrm{ma}0}{\mathrm{d\&Phi;}}_{13}/\mathrm{dt}-R_{m0}{\mathrm{d\&Phi;}}_{15}/\mathrm{dt}=-{\mathrm{dF}}_s/\mathrm{dt}\\ (R_{m0}+R_{\mathrm{md}3}){\mathrm{d\&Phi;}}_{15}/\mathrm{dt}-R_{m0}{\mathrm{d\&Phi;}}_{14}/\mathrm{dt}=0\end{array}\right.---(14-b)$

$\frac{d}{\mathrm{dt}}\left(\begin{array}{c}{\mathrm{\&Psi;}}_p\\ {\mathrm{\&Psi;}}_s\end{array}\right)=\left(\begin{array}{ccc}{N}_p& 0& 0\\ -N_s& 0& 0\end{array}\right)\left(\begin{array}{c}{\mathrm{\&Phi;}}_1\\ {\mathrm{\&Phi;}}_2\\ {\mathrm{\&Phi;}}_3\end{array}\right)---(14-c)$

$\left(\begin{array}{c}-{\mathrm{dF}}_p/\mathrm{dt}+{\mathrm{dF}}_s/\mathrm{dt}\\ 0\\ {\mathrm{dF}}_p/\mathrm{dt}\\ -{\mathrm{dF}}_s/\mathrm{dt}\\ 0\end{array}\right)=\left(\begin{array}{cc}{-N}_p& N_s\\ 0& 0\\ N_p& 0\\ 0& {-N}_s\\ 0& 0\end{array}\right)---(14-d)$

4. based on 3 step conclusions, derivation differential inductance matrix

First give transformer differential magnetic circuit modeling basic theories, magnetization characteristic representation unshakable in one's determination, iron core vortex loss expression formula above, which together form Transformer Modeling basic theories herein.Differential inductance matrix is the bridge of connection transformer magnetic circuit-circuit, characterizes iron core cutter characteristic and hysteresis effect.Differential inductance matrix L _dfor:

dΨ/dt＝L _d(dI _ps/dt) (15)

Wherein, Ψ is former and deputy limit winding magnetic linkage matrix, I _psfor former and deputy limit winding current matrix.

(11), (12), (13) formula are substituted into (15) formula, obtains differential inductance matrix L _d:

$\begin{array}{c}\frac{\mathrm{d\&Psi;}}{\mathrm{dt}}=N_{\mathrm{\&Psi;}}\frac{\mathrm{d\&Phi;}}{\mathrm{dt}}=N_{\mathrm{\&Psi;}}C\left(R^{-1}\frac{\mathrm{dF}}{\mathrm{dt}}\right)=N_{\mathrm{\&Psi;}}{\mathrm{CR}}^{-1}\left(N_F\frac{{\mathrm{dI}}_{\mathrm{ps}}}{\mathrm{dt}}\right)=L_d\frac{{\mathrm{dI}}_{\mathrm{ps}}}{\mathrm{dt}}\\ \&DoubleRightArrow;L_d=N_{\mathrm{\&Psi;}}{\mathrm{CR}}^{-1}{N}_F\end{array}---\left(16\right)$

For single-phase three post core type transformers, by (14-a), (14-b), (14-c), (14-d) formula substitute into (15) formula, differential inductance matrix L _d.

5. connect form based on single transformer winding, set up Single Phase Transformer Set circuit model

Based on above-mentioned theory, according to core structure and the winding coupling form of transformer, differential inductance matrix rapid solving can be realized, and then set up transformer DC magnetic bias model, realize transformer DC magnetic bias emulation.According to the detailed magnetic circuit model of core type transformer, derived below single transformer eddy current loss resistance and differential inductance matrix expression formula.

Connect single-phase three pillar type transformer (Figure 11 shows) for Y/Y, according to 1 ~ 4 part derivation equation, listing circuit equation is:

Wherein, E is primary side end voltage matrix, r _p, r _sbe respectively former and deputy limit winding resistance matrix, L _p, L _sbe respectively former and deputy limit winding inductance matrix, I _p, I' _pfor former limit winding current matrix, the latter comprises Eddy Current Loss In Core of An Electromagnetic electric current.

According to (17) formula, can realize Y/Y tietransformer no-load running characteristic research.When winding connects form difference, can obtain different circuit equation, realize DC magnetic biasing time-domain-simulation, general type is:

Wherein p, s represent former and deputy limit respectively, and R, L are respectively resistance, inductance matrix, and K represents unit matrix.

6., based on numerical algorithm, solve transformer differentiating circuit system of equations, ask for target variable

In Matlab software, use method of finite difference or Finite-Difference Time-Domain Method (FDTD) to carry out discretize to (18), algebraic equation is turned to by the differential equation, carry out numerical iteration, the parameters such as the exciting current of transformer when nominal situation and DC magnetic biasing, magnetic are close, magnetic field intensity can be tried to achieve.

7. model Trusting eBusiness

Based on such as formula monodrome magnetization curve (19) Suo Shi, calculate document and survey no-load transformer excitation surge current, result represents in fig. 12.

$H=1248\tan \left(\frac{\mathrm{\&pi;}}{4.26}B\right)---\left(19\right)$

As can be seen from Figure 11, front 4 the excitation surge current peak values of this model emulation result are respectively: 161.7,60,39.6,31.3A, document measurement result is 161.7,63,38.6,29.2A, show that result of calculation and document measured result meet better, prove the validity of this paper model herein.

Claims (4)

1. equivalent differential electricity (magnetic) road principle calculates DC magnetic biasing single transformer model, it is characterized in that: comprise the following steps: a., based on monophase transformer core topological structure and transformer parameter, sets up circuit model;

B. based on differential magnetic circuit principle, differential magnetic circuit model is set up;

C. based on transformer differential magnetic circuit model, derivation iron core differential magnetic flux, differential mmf, magnetic linkage and loop differential flux relationship formula;

D. based on first three steps conclusion, derivation differential inductance matrix;

E. connect form and differential electric pole matrix based on single transformer winding, set up Single Phase Transformer Set circuit model;

F. based on numerical algorithm, solve transformer differentiating circuit system of equations, ask for target variable;

G. model Trusting eBusiness.

2. equivalent differential electricity (magnetic) road as claimed in claim 1 principle calculates DC magnetic biasing single transformer model, it is characterized in that: in step a, characterizes transformer core eddy current loss by non-linear resistance.

3. equivalent differential electricity (magnetic) road as claimed in claim 1 principle calculates DC magnetic biasing single transformer model, it is characterized in that: in step b, based on single transformer parameter, sets up transformer differential magnetic circuit model.

4. equivalent differential electricity (magnetic) road as claimed in claim 1 principle calculates DC magnetic biasing single transformer model, it is characterized in that: in step f, use Matlab software simulating numerical algorithm, obtain that the exciting current of transformer when normal operating conditions and DC magnetic biasing, magnetic are close, magnetic field intensity.