CN106546811A - The detection method and system of transformer load loss under a kind of harmonic current - Google Patents

Abstract

The invention discloses under a kind of harmonic current transformer load loss detection method and system, method and step includes secondary current virtual value I for detecting transformator first, individual harmonic current value is obtained according to secondary current virtual value I and the winding resistance harmonic loss factor is calculated according to formula (9), transformer load loss under harmonic current is calculated according to formula (10) then；System is the detecting system with transformer load loss under preceding method completely corresponding harmonic current, specifically includes winding resistance harmonic loss factor specifying unit and load loss computing unit.The present invention has taken into full account under high-frequency ac that actual resistance is compared with the situation that D.C. resistance can increase under the kelvin effect and harmonic current of winding conducting wire, winding resistance loss by calculating transformer under harmonic current further obtains load loss computation model of the new transformator under harmonic current so that under harmonic current, winding resistance loss calculation is more accurate.

Description

The detection method and system of transformer load loss under a kind of harmonic current

Technical field

The present invention relates to transformer load loss detection technique under harmonic current, and in particular to transformation under a kind of harmonic current The detection method and system of device load loss.

Background technology

Used as the nucleus equipment of power transmission and distribution, the running status of transformator directly influences the safety and stablization of power system, Its loss is can not be ignored for the impact of economical operation is even more.According to investigations, in nationwide integrated power grid, transformer loss accounts for generating total amount 3%, distribution transformer loss account for the 60%～80% of whole losses of distribution network.In recent years, industrial frequency conversion equipment and high frequency The nonlinear-loads such as device are used widely, and these nonlinear-loads produce a large amount of harmonic currents, and harmonic current is not only resulted in Transformer loss increases, and the harmful effect evidences such as temperature rising, decreasing insulating, insulation life shortening can be also caused to transformator The data that Central Japan Utilities Electric Co. provides, when 5 subharmonic current containing ratios are 10%, transformer loss increases by 10%.According to phase Pass data, the insulation life loss of transformator 50% is what the heat effect produced by harmonic current was caused.Therefore, study harmonic wave electricity The lower transformer load loss computational methods of stream effect are significant.

At present, when the load loss under harmonic current is calculated in IEEE Std C57.110, first define winding vortex Harmonic loss factor F_HL-ECWith spuious harmonic loss factor F_HL-OSLAs shown in formula (1) and (2)；Then by the winding whirlpool of definition Stream harmonic loss factor F_HL-ECWith spuious harmonic loss factor F_HL-OSL, calculate the lower winding eddy current loss of harmonic current effect with it is miscellaneous Shown in scattered harmonic loss such as formula (4) and (5)；

In formula (1) and (2), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I is the pair by transformator Side current effective value, I_hFor h subharmonic currents；Shown in the expression formula such as formula (3) of secondary current virtual value I of transformator；

In formula (3), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor h subharmonic currents.

P_EC-H=F_HL-ECP_EC-O (4)

P_OSL-H=F_HL-OSLP_OSL-O (5)

In formula (4) and (5), P_EC-HFor the lower winding eddy current loss of harmonic current effect, P_EC-OFor power frequency is for power frequency but has Winding eddy current loss when valid value is I, P_OSL-HFor the lower stray loss of harmonic current effect, P_OSL-OFor power frequency be power frequency but Stray loss when virtual value is I, F_HL-ECThe harmonic loss factor, F are vortexed for winding_HL-OSLFor the spuious harmonic loss factor.Its In, power frequency is the winding eddy current loss P of power frequency but virtual value when being I_EC-OWith stray loss P_OSL-OIt is specified with transformator Under the conditions of eddy-current loss it is relevant with stray loss and current effective value, can by formula (6) and function expression shown in (7) calculating Obtain；

In formula (6) and (7), P_EC-OFor power frequency be power frequency but virtual value be I when winding eddy current loss, P_OSL-OFor electricity Stream frequency is the stray loss of power frequency but virtual value when being I, P_EC-RFor winding eddy current loss under rated condition；P_OSL-RFor specified bar Stray loss under part, I_RFor rated current.

But when the resistance loss of winding is calculated, IEEE Std C57.110 are directly with the D.C. resistance of Transformer Winding Calculated, have ignored kelvin effect and kindred effect of the winding under high-frequency ac, its result of calculation limited accuracy.IEEE Load loss Ps of the Std C57.110 to transformator under harmonic current_LL-HShown in computation model such as formula (8)；

P_LL-H=I²R+F_HL-ECP_EC-O+F_HL-OSLP_OSL-O (8)

In formula (8), I is the secondary current virtual value by transformator, D.C. resistances of the R for Transformer Winding, F_HL-ECFor Winding is vortexed the harmonic loss factor, F_HL-OSLFor the spuious harmonic loss factor, P_EC-OFor power frequency is for power frequency but virtual value is I When winding eddy current loss, P_OSL-OFor power frequency be power frequency but virtual value be I when stray loss.

But, when under calculating transformer harmonic current, winding resistance is lost, the calculating side of existing IEEE Std C57.110 Method method does not consider kelvin effect and kindred effect of the winding conducting wire under high-frequency ac, using the D.C. resistance of winding conducting wire Replace the AC resistance under high-frequency ac, therefore calculated load loss accuracy is not high.

The content of the invention

The technical problem to be solved in the present invention：For the problems referred to above of prior art, there is provided one kind has taken into full account high frequency Under the kelvin effect and harmonic current of the lower winding conducting wire of exchange, actual resistance is compared with the situation that D.C. resistance can increase so that humorous Under ripple electric current under the more accurate harmonic current of winding resistance loss calculation transformer load loss detection method and system.

In order to solve above-mentioned technical problem, the technical solution used in the present invention is：

On the one hand, the present invention provides a kind of detection method of transformer load loss under harmonic current, and implementation steps include：

1) secondary current virtual value I of transformator is detected, individual harmonic current value is obtained according to secondary current virtual value I, The winding resistance harmonic loss factor is calculated according to formula (9)

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor in secondary current virtual value I H subharmonic currents, I are secondary current virtual value；

2) transformer load loss P under harmonic current is calculated according to formula (10)_LL-H；

In formula (10), I be secondary current virtual value, I_RFor rated current, F_HL-ECThe harmonic loss factor is vortexed for winding, F_HL-OSLFor the spuious harmonic loss factor, F_HL-I2RFor the winding resistance harmonic loss factor, P_EC-RIt is vortexed for winding under rated condition Loss, P_OSL-RFor stray loss under rated condition, P_I ² _R-RIt is lost for the winding resistance under rated condition.

Preferably, step 2) in calculate harmonic current under transformer load loss P_LL-HWhen, winding vortex under rated condition Loss P_EC-R, stray loss P under rated condition_OSL-R, winding resistance loss P under rated condition_I ² _R-RDetermination mode it is as follows：It is first First judge the type of transformator, if transformator is dry-type transformer, winding vortex under rated condition is determined according to formula (11) Loss P_EC-R, stray loss P under rated condition_OSL-R, winding resistance loss P under rated condition_I ² _R-R；If transformator is oil immersion Formula transformator, then determine winding eddy current loss P under rated condition according to formula (12)_EC-R, stray loss P under rated condition_OSL-R, volume Winding resistance loss P under fixed condition_I ² _R-R；

In formula (11) and formula (12), P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor spuious damage under rated condition Consumption, P_I ² _R-RIt is lost for the winding resistance under rated condition, P_LL-RFor the load loss under transformator rated condition.

On the other hand, the present invention also provides a kind of detecting system of transformer load loss under harmonic current, including：

Winding resistance harmonic loss factor specifying unit, for detecting secondary current virtual value I of transformator, according to secondary Current effective value I obtains individual harmonic current value, calculates the winding resistance harmonic loss factor according to formula (9)

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor in secondary current virtual value I H subharmonic currents, I are secondary current virtual value；

Load loss computing unit, for calculating transformer load loss P under harmonic current according to formula (10)_LL-H；

In formula (10), I be secondary current virtual value, I_RFor rated current, F_HL-ECThe harmonic loss factor is vortexed for winding, F_HL-OSLFor the spuious harmonic loss factor,For the winding resistance harmonic loss factor, P_EC-RIt is vortexed for winding under rated condition Loss, P_OSL-RFor stray loss under rated condition, P_I ² _R-RIt is lost for the winding resistance under rated condition.

Preferably, the load loss computing unit includes loss calculation module, and the loss calculation module calculates harmonic wave Transformer load loss P under electric current_LL-HWhen, winding eddy current loss P under rated condition_EC-R, stray loss P under rated condition_OSL-R、 Winding resistance loss P under rated condition_I ² _R-RDetermination mode it is as follows：Judge the type of transformator, if transformator is dry type Transformator, then determine winding eddy current loss P under rated condition according to formula (11)_EC-R, stray loss P under rated condition_OSL-R, it is specified Under the conditions of winding resistance loss P_I ² _R-R；If transformator is oil-filled transformer, determined under rated condition according to formula (12) Winding eddy current loss P_EC-R, stray loss P under rated condition_OSL-R, winding resistance loss P under rated condition_I ² _R-R；

In formula (11) and formula (12), P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor spuious damage under rated condition Consumption, P_I ² _R-RIt is lost for the winding resistance under rated condition, P_LL-RFor the load loss under transformator rated condition.

The detection method tool of transformer load loss under harmonic current of the present invention has the advantage that：Under harmonic current of the present invention The detection method of transformer load loss detects secondary current virtual value I of transformator, is obtained respectively according to secondary current virtual value I Subharmonic current value, calculates the winding resistance harmonic loss factor according to formula (9), calculates transformation under harmonic current further according to formula (10) Device load loss, has taken into full account that actual resistance is more straight under the kelvin effect and harmonic current of winding conducting wire under high-frequency ac The situation that leakage resistance can increase, the winding resistance loss by calculating transformer under harmonic current further obtain new transformator Load loss computation model under harmonic current so that winding resistance loss calculation is more accurate under harmonic current.

Description of the drawings

Basic procedure schematic diagrams of the Fig. 1 for present invention method.

Specific embodiment

As shown in figure 1, the implementation steps of the detection method of transformer load loss include under the present embodiment harmonic current：

1) secondary current virtual value I of transformator is detected, individual harmonic current value is obtained according to secondary current virtual value I, The winding resistance harmonic loss factor is calculated according to formula (9)

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor in secondary current virtual value I H subharmonic currents, I are secondary current virtual value；

2) transformer load loss P under harmonic current is calculated according to formula (10)_LL-H；

In formula (10), I be secondary current virtual value, I_RFor rated current, F_HL-ECThe harmonic loss factor is vortexed for winding, F_HL-OSLFor the spuious harmonic loss factor,For the winding resistance harmonic loss factor, P_EC-RIt is vortexed for winding under rated condition Loss, P_OSL-RFor stray loss under rated condition, P_I ² _R-RIt is lost for the winding resistance under rated condition.

In the present embodiment, the specific derivation process of formula (9) is as follows：

When transformator is run under rated condition, total winding resistance loss is first and second side winding resistance loss sum, because This has function expression shown in formula (9-1)；

In formula (9-1),It is lost for winding resistance,For power frequency be power frequency but virtual value be I when winding electricity Resistance loss value, I₍₁₎For primary current, I₍₂₎For secondary current, R₍₁₎For winding resistance of the first winding under fundamental current effect Value, R₍₂₎For winding resistance of the first winding under fundamental current effect.

Winding resistance loss is understood based on formula (9-1)With power current virtual value be I when winding resistance loss valueIt is equal.Consider the impact of winding kelvin effect under harmonic current, AC resistance such as formula (9-2) institute of unit length conductor Show；

In formula (9-2), R represents the AC resistance of unit length conductor, and r is conductor radius, and σ is conductor conductivity, δ_nFor h Skin depth under subfrequency；δ₁For the skin depth under rated frequency, ω is power current angular frequency, and μ is conductor Pcrmeability.From formula (9-2), the resistance value when resistance value of h subharmonic currents effect lower conductor is rated currentTimes, Obviously harmonic wave has considerable influence to the resistance of winding.

When there is harmonic wave, the winding resistance loss P of transformator_I ² _R-HShown in computing formula such as formula (9-3)；

In formula (9-3), I₍₁₎For primary side current virtual value, I₍₂₎For the virtual value of secondary side current, R₍₁₎For first winding Winding resistance under fundamental current effect, R₍₂₎For winding resistance of the Secondary Winding under fundamental current effect；H is humorous Ripple current times, h_maxFor highest harmonic current number of times, I_hFor h subharmonic currents, I_h(1)For the h subharmonic electricity of once winding current Stream, I_h(2)For the h subharmonic currents of secondary winding electric current.

The relation of first and second side electric current of transformator and umber of turn as shown in formula (9-4) is substituted into into formula (9-3), then can be with Obtain function expression shown in formula (9-5)；

In formula (9-4) and formula (9-5), I₍₁₎For primary side current virtual value, I₍₂₎For the virtual value of secondary side current, N₁For The number of turn of first winding, N₂For the number of turn of Secondary Winding, I_h(1)For the h subharmonic currents of once winding current, I_h(2)For it is secondary around The h subharmonic currents of group electric current；H be harmonic current number of times, h_maxFor highest harmonic current number of times, R₍₁₎It is first winding in fundamental wave Winding resistance under the function of current, R₍₂₎For winding resistance of the first winding under fundamental current effect, P_I ² _R-HFor transformator Under harmonic current winding resistance loss.

Formula (9-5) can be reduced to formula (9-6) by convolution (9-1)；

In formula (9-6), P_I ² _R-HWinding resistance for transformator is lost, P_I ² _R-OFor power frequency is for power frequency but virtual value is I When winding resistance loss, h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_h(2)For the h of secondary winding electric current Subharmonic current；I₍₂₎For the virtual value of secondary side current.Therefore, according to whirlpool in the similar IEEE Std C57.110 of formula (18) Stream harmonic loss factor F_HL-ECWith spuious harmonic loss factor F_HL-OSLDefinition method, define the winding resistance harmonic loss factor F_HL-I ² _RAs shown in formula (9-7)；

In formula (9-7), F_HL-I ² _RFor the winding resistance harmonic loss factor, P_I ² _R-HWinding resistance for transformator is lost, P_I ² _R-OFor power current virtual value be I when winding resistance loss value, h be harmonic current number of times, h_maxFor highest harmonic current Number, I_h(2)For the h subharmonic currents of secondary winding electric current；I₍₂₎For the virtual value of secondary side current, its expression formula such as formula (9-8) It is shown.

In formula (9-8), I₍₂₎For the virtual value of secondary side current, h is harmonic current number of times, h_maxFor highest harmonic current Number, I_h(2)For the h subharmonic currents of secondary side current.

It should be noted that what harmonic wave was typically introduced by the nonlinear-load of step down side, after transformator, Substantially reduce to high-pressure side harmonic content；So the present invention consideration load-side is the harmonic wave situation of secondary side, secondary side current Virtual value I₍₂₎Total current virtual value I of transformator is expressed as, therefore by the h subharmonic of the secondary winding electric current in formula (9-7) Electric current I_h(2)H subharmonic current I are used then_hReplace, virtual value I of secondary side current₍₂₎For total current virtual value I.So formula (9-7) Function expression shown in the formula that obtains (9) can further be simplified.

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor h subharmonic currents, I is to become The total current virtual value of depressor, by detecting secondary current virtual value I₍₂₎Obtain.

In the present embodiment, the specific derivation process of formula (10) is as follows：

Calculating winding resistance harmonic loss factor F_HL-I ² _ROn the basis of, using the winding resistance harmonic loss factor F_HL-I ² _RCalculate shown in the formula such as formula (10-1) of the lower added losses of harmonic current effect；

In formula (10-1), P_I2R-HFor the lower added losses of harmonic current effect, F_HL-I ² _RFor the winding resistance harmonic loss factor,For power frequency be power frequency but virtual value be I when winding resistance loss value.Wherein, power frequency is power frequency but virtual value For I when winding resistance loss valueCalculating function expression such as formula (10-2) shown in；

In formula (10-2),For power frequency be power frequency but virtual value be I when winding resistance loss value, I is to pass through The virtual value of transformer current, I_RFor rated current,It is lost for the winding resistance under rated condition.

As discussed above, the present embodiment will allow for kelvin effect and kindred effect of the winding conducting wire under high-frequency ac, fixed An adopted winding resistance harmonic loss factor, winding resistance loss of the calculating transformer under harmonic current, and then obtain new Shown in load loss computation model such as formula (10-3) of the transformator under harmonic current；

In formula (10-3), P_LL-HFor transformer load loss under harmonic current, F_HL-ECThe harmonic loss factor is vortexed for winding, F_HL-OSLFor the spuious harmonic loss factor,For the winding resistance harmonic loss factor, P_EC-OFor power frequency is for power frequency but has Winding eddy current loss when valid value is I, P_OSL-HLower stray loss is acted on for harmonic current,For power frequency be power frequency but Winding resistance loss value when virtual value is I.As discussed above, winding eddy current loss P_EC-OWith stray loss P_OSL-OWith transformator Eddy-current loss under rated condition is relevant with stray loss and current effective value, can pass through formula (6) and function expression shown in (7) It is calculated；Winding resistance loss value with reference to when the power frequency as shown in formula (10-2) is power frequency but virtual value is I's Calculate function expression, you can obtain formula (10).

Correlational study shows that winding resistance loss under transformator rated condition is the major part of load loss, accounts for bearing The 80% of load-loss, added losses account for 20%.And for oil-filled transformer, winding eddy current loss accounts for stray loss 33%, for dry-type transformer, winding eddy current loss accounts for the 67% of stray loss, in the present embodiment, step 2) in calculate it is humorous Transformer load loss P under ripple electric current_LL-HWhen, winding eddy current loss P under rated condition_EC-R, stray loss under rated condition P_OSL-R, winding resistance loss P under rated condition_I ² _R-RDetermination mode it is as follows：The type of transformator is first determined whether, if become Depressor is dry-type transformer, then determine winding eddy current loss P under rated condition according to formula (11)_EC-R, spuious damage under rated condition Consumption P_OSL-R, winding resistance loss P under rated condition_I ² _R-R；If transformator is oil-filled transformer, according to formula (12) really Winding eddy current loss P under quota fixed condition_EC-R, stray loss P under rated condition_OSL-R, winding resistance loss under rated condition P_I ² _R-R；

In formula (11) and formula (12), P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor spuious damage under rated condition Consumption, P_I ² _R-RIt is lost for the winding resistance under rated condition, P_LL-RFor the load loss under transformator rated condition.

Under the present embodiment harmonic current, the detection method of transformer load loss is mainly by computer program to realize , included by the detecting system of transformer load loss under the harmonic current that the computer program is realized：

Winding resistance harmonic loss factor specifying unit, for detecting secondary current virtual value I of transformator, according to secondary Current effective value I obtains individual harmonic current value, calculates the winding resistance harmonic loss factor according to formula (9)

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor in secondary current virtual value I H subharmonic currents, I are secondary current virtual value；

Load loss computing unit, for calculating transformer load loss P under harmonic current according to formula (10)_LL-H；

In formula (10), I be secondary current virtual value, I_RFor rated current, F_HL-ECThe harmonic loss factor is vortexed for winding, F_HL-OSLFor the spuious harmonic loss factor,For the winding resistance harmonic loss factor, P_EC-RIt is vortexed for winding under rated condition Loss, P_OSL-RFor stray loss under rated condition, P_I ² _R-RIt is lost for the winding resistance under rated condition.

In the present embodiment, load loss computing unit includes loss calculation module, and loss calculation module calculates harmonic current Lower transformer load loss P_LL-HWhen, winding eddy current loss P under rated condition_EC-R, stray loss P under rated condition_OSL-R, it is specified Under the conditions of winding resistance loss P_I ² _R-RDetermination mode it is as follows：Judge the type of transformator, if transformator is dry type transformation Device, then determine winding eddy current loss P under rated condition according to formula (11)_EC-R, stray loss P under rated condition_OSL-R, rated condition Under winding resistance loss P_I ² _R-R；If transformator is oil-filled transformer, winding under rated condition is determined according to formula (12) Eddy-current loss P_EC-R, stray loss P under rated condition_OSL-R, winding resistance loss P under rated condition_I ² _R-R；

In formula (11) and formula (12), P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor spuious damage under rated condition Consumption, P_I ² _R-RIt is lost for the winding resistance under rated condition, P_LL-RFor the load loss under transformator rated condition.

In sum, as the detection method of transformer load loss under the present embodiment harmonic current and system consider high frequency The kelvin effect of the lower winding conducting wire of exchange, it is contemplated that actual resistance can increase compared with D.C. resistance under harmonic current, define The winding resistance harmonic loss factor, makes winding resistance loss calculation under harmonic current more accurate, is defining winding resistance harmonic wave During fissipation factor, engineering is derived clear and more succinct.The detection of transformer load loss under the present embodiment harmonic current Method and system will allow for kelvin effect and kindred effect of the winding conducting wire under high-frequency ac, define a winding resistance humorous Ripple fissipation factor, winding resistance loss of the calculating transformer under harmonic current, and then new transformator is obtained in harmonic current Under load loss computation model, calculate under harmonic wave transformer load loss more simple and accurate.

The above is only the preferred embodiment of the present invention, and protection scope of the present invention is not limited merely to above-mentioned enforcement Example, all technical schemes belonged under thinking of the present invention belong to protection scope of the present invention.It should be pointed out that for the art Those of ordinary skill for, some improvements and modifications without departing from the principles of the present invention, these improvements and modifications Should be regarded as protection scope of the present invention.

Claims (4)

1. under a kind of harmonic current transformer load loss detection method, it is characterised in that implementation steps include：

1) secondary current virtual value I of transformator is detected, individual harmonic current value is obtained according to secondary current virtual value I, according to Formula (9) calculates the winding resistance harmonic loss factor

$F_{HL-I^{2}R}=\frac{\underset{h=1}{\overset{h=h_{\max }}{\Σ}}{\[\frac{I_h}{I}\]}^2{h}^{0.5}}{\underset{h=1}{\overset{h=h_{\max }}{\Σ}}{\[\frac{I_h}{I}\]}^2}---\left(9\right)$

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor the h time in secondary current virtual value I Harmonic current, I are secondary current virtual value；

2) transformer load loss P under harmonic current is calculated according to formula (10)_LL-H；

$P_{LL-H}={\left(\frac{I}{I_R}\right)}^2(F_{HL-EC}{P}_{EC-R}+F_{HL-OSL}{P}_{OSL-R}+F_{HL-I^{2}R}{P}_{I^{2}R-R})---\left(10\right)$

In formula (10), I be secondary current virtual value, I_RFor rated current, F_HL-ECThe harmonic loss factor, F are vortexed for winding_HL-OSL For the spuious harmonic loss factor,For the winding resistance harmonic loss factor, P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor stray loss under rated condition,It is lost for the winding resistance under rated condition.

2. under harmonic current according to claim 1 transformer load loss detection method, it is characterised in that step 2) Transformer load loss P under middle calculating harmonic current_LL-HWhen, winding eddy current loss P under rated condition_EC-R, it is spuious under rated condition Loss P_OSL-R, winding resistance loss under rated conditionDetermination mode it is as follows：The type of transformator is first determined whether, such as Fruit transformator is dry-type transformer, then determine winding eddy current loss P under rated condition according to formula (11)_EC-R, it is miscellaneous under rated condition Dissipate loss P_OSL-R, winding resistance loss under rated conditionIf transformator is oil-filled transformer, according to formula (12) determine winding eddy current loss P under rated condition_EC-R, stray loss P under rated condition_OSL-R, winding electricity under rated condition Resistance loss

$\left\{\begin{array}{c}{P}_{I^{2}R-R}=0.8P_{LL-R}\\ P_{OSL-R}=0.12P_{LL-R}\\ P_{EC-R}=0.08P_{LL-R}\end{array}\right.---\left(11\right)$

$\left\{\begin{array}{c}{P}_{I^{2}R-R}=0.8P_{LL-R}\\ P_{OSL-R}=0.15P_{LL-R}\\ P_{EC-R}=0.05P_{LL-R}\end{array}\right.---\left(12\right)$

In formula (11) and formula (12), P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor stray loss under rated condition,It is lost for the winding resistance under rated condition, P_LL-RFor the load loss under transformator rated condition.

3. under a kind of harmonic current transformer load loss detecting system, it is characterised in that include：

Winding resistance harmonic loss factor specifying unit, for detecting secondary current virtual value I of transformator, according to secondary current Virtual value I obtains individual harmonic current value, calculates the winding resistance harmonic loss factor according to formula (9)

$F_{HL-I^{2}R}=\frac{\underset{h=1}{\overset{h=h_{\max }}{\Σ}}{\[\frac{I_h}{I}\]}^2{h}^{0.5}}{\underset{h=1}{\overset{h=h_{\max }}{\Σ}}{\[\frac{I_h}{I}\]}^2}---\left(9\right)$

In formula (9), h be harmonic current number of times, h_maxFor highest harmonic current number of times, I_hFor the h time in secondary current virtual value I Harmonic current, I are secondary current virtual value；

Load loss computing unit, for calculating transformer load loss P under harmonic current according to formula (10)_LL-H；

$P_{LL-H}={\left(\frac{I}{I_R}\right)}^2(F_{HL-EC}{P}_{EC-R}+F_{HL-OSL}{P}_{OSL-R}+F_{HL-I^{2}R}{P}_{I^{2}R-R})---\left(10\right)$

In formula (10), I be secondary current virtual value, I_RFor rated current, F_HL-ECThe harmonic loss factor, F are vortexed for winding_HL-OSL For the spuious harmonic loss factor,For the winding resistance harmonic loss factor, P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor stray loss under rated condition,It is lost for the winding resistance under rated condition.

4. under harmonic current according to claim 3 transformer load loss detecting system, it is characterised in that it is described negative Load-loss computing unit includes loss calculation module, and the loss calculation module calculates transformer load loss under harmonic current P_LL-HWhen, winding eddy current loss P under rated condition_EC-R, stray loss P under rated condition_OSL-R, winding resistance under rated condition LossDetermination mode it is as follows：Judge the type of transformator, if transformator is dry-type transformer, according to formula (11) Determine winding eddy current loss P under rated condition_EC-R, stray loss P under rated condition_OSL-R, the winding resistance under rated condition damages ConsumptionIf transformator is oil-filled transformer, winding eddy current loss P under rated condition is determined according to formula (12)_EC-R, volume Stray loss P under fixed condition_OSL-R, winding resistance loss under rated condition

$\left\{\begin{array}{c}{P}_{I^{2}R-R}=0.8P_{LL-R}\\ P_{OSL-R}=0.12P_{LL-R}\\ P_{EC-R}=0.08P_{LL-R}\end{array}\right.---\left(11\right)$

$\left\{\begin{array}{c}{P}_{I^{2}R-R}=0.8P_{LL-R}\\ P_{OSL-R}=0.15P_{LL-R}\\ P_{EC-R}=0.05P_{LL-R}\end{array}\right.---\left(12\right)$

In formula (11) and formula (12), P_EC-RFor winding eddy current loss under rated condition, P_OSL-RFor stray loss under rated condition,It is lost for the winding resistance under rated condition, P_LL-RFor the load loss under transformator rated condition.