CN104237673A - Method for estimating harmonic loss of transformer - Google Patents

Abstract

The invention discloses a method for estimating the harmonic loss of a transformer, and belongs to the technical field of electric system energy saving. The method comprises the steps that the iron core loss of the transformer under fundamental waves is analyzed and calculated; the winding loss of the transformer under the fundamental waves is analyzed and calculated; two parameters needed in estimation are calculated according to the measured data of the harmonic loss of the transformer; finally, the harmonic loss of the transformer is estimated. According to the method for estimating the harmonic loss of the transformer, the harmonic loss of the transformer can be estimated easily and fast according to the measured data, certain rationality and accuracy are achieved, and the method can be applied to energy saving and loss reduction work.

Description

A kind of evaluation method of transformer harmonic loss

Technical field

The invention belongs to Energy Saving Technique of Electric Power System field, particularly relate to a kind of transformer harmonic loss evaluation method.

Background technology

Transformer contacts the indispensable electrical equipment of different electric pressure networks in electric system, is extensively present in network at different levels.In general, from generating power supply, until electricity consumption, the transformation process through three to four times is needed.Therefore, not only total number of units of transformer will exceed total number of units of generator, and the total volume of operating transformer also far exceedes the total volume running generator simultaneously, and also exceedes the total volume of service meter.Because transformer is a kind of static electrical equipment, in conversion process of energy, there is no mechanical loss, so its efficiency is higher than the electric rotating machine with capacity.But because transformer is power-supply device, usual and load increases and decreases irrelevant, is continuous working, even so some loss, with year, office calculates, and also just seems especially large.According to statistics, the total losses of transformer have about accounted for 8% of gross generation.It should be noted that, along with the development of electric power and electronic technology, the character of generating and consumer is increasingly sophisticated, the various nonlinear elements dropping into electrical network are increasing, the aggravation that Harmonious Waves in Power Systems is polluted, harmonic wave causes many adverse influences to transformer, especially adds the loss of transformer.

The calculating of transformer harmonic loss, usually on the basis obtaining a large amount of measured datas, adopts the method for curve, the equivalent parameters of transformer under calculating each harmonic, and obtains total harmonic loss by superposition principle method.This computing method meet the precision methods of estimation to a certain extent, but computation process is comparatively loaded down with trivial details and required data volume is many, has certain defect.

Summary of the invention

The object of the present invention is to provide a kind of evaluation method of transformer harmonic loss, for the economic analysis of calculating transformer harmonic loss and electrical network rapidly, there is strong adaptability, calculate easy feature.

To achieve these goals, the technical scheme that the present invention proposes is a kind of simple Estimating Method of transformer harmonic loss, it is characterized in that described method comprises:

Step 1: the core loss of analytical calculation transformer under first-harmonic, first-harmonic core loss is:

$P_{\mathrm{Fe}}=P_F\·{\left(\frac{U_1}{U_N}\right)}^2---\left(1\right)$

Wherein: P _fethe first-harmonic core loss of transformer during for running,

P _fcore loss during operation specified for transformer is the technical parameter of transformer,

U ₁for the effective value of side line voltage when transformer runs,

U _nfor the rated voltage of transformer primary side;

Step 2: the winding loss of analytical calculation transformer under first-harmonic, first-harmonic winding loss is:

$P_{\mathrm{Cu}}=P_C\·{\left(\frac{\sqrt{3}{I}_1{U}_N}{S_N}\right)}^2---\left(2\right)$

Wherein: P _cuthe first-harmonic winding loss of transformer during for running,

P _cwinding loss during operation specified for transformer is the technical parameter of transformer,

I ₁for the effective value of primary side line current when transformer runs,

U _nfor the rated voltage of transformer primary side,

S _nfor transformer rated capacity;

Step 3: according to the measured data of the harmonic wave of transformer, calculates two parameters needed for estimation;

${\mathrm{\α}}_1=\underset{h=2}{\mathrm{\Σ}}h\·{\mathrm{THD}}_h^2---\left(3\right)$

Wherein: α ₁for one of required parameter,

H is the number of times of harmonic wave,

THD _hfor the aberration rate of individual harmonic current,

${\mathrm{\α}}_2=\underset{h=2}{\mathrm{\Σ}}{\mathrm{THD}}_h^2---\left(4\right)$

Wherein: α ₂for one of required parameter,

H is the number of times of harmonic wave,

THD _hfor the aberration rate of each harmonic.

Step 4: the result obtained according to step above, estimation transformer harmonic loss;

ΔP＝P _Cu·α ₁+P _Fe·α ₂ (5)

Wherein: P _fethe first-harmonic core loss of transformer during for running,

P _cuthe first-harmonic winding loss of transformer during for running,

α ₁, α ₂for the parameter that step 3 calculates.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of the simple Estimating Method of transformer harmonic loss;

Fig. 2 is transformer each harmonic T-shape equivalent circuit schematic diagram.

Embodiment

Below in conjunction with accompanying drawing, preferred embodiment is elaborated.It is emphasized that following explanation is only exemplary, instead of in order to limit the scope of the invention and apply.

Embodiment 1

Fig. 1 is the process flow diagram of the simple Estimating Method of transformer harmonic loss.This evaluation method utilizes superposition principle on the basis of the transformer each harmonic T-shape equivalent circuit shown in Fig. 2, obtains through reasonably simplifying.As shown in Figure 1, the simple Estimating Method of the transformer harmonic loss of the present invention's proposition comprises:

Step 1: the core loss of analytical calculation transformer under first-harmonic, first-harmonic core loss is:

$P_{\mathrm{Fe}}=P_F\·{\left(\frac{U_1}{U_N}\right)}^2---\left(1\right)$

Wherein: P _fethe first-harmonic core loss of transformer during for running,

P _fcore loss during operation specified for transformer is the technical parameter of transformer,

U ₁for the effective value of side line voltage when transformer runs,

U _nfor the rated voltage of transformer primary side;

In the operation of reality, transformer first-harmonic core loss almost can think constant, therefore also known as fixed loss.

Step 2: the winding loss of analytical calculation transformer under first-harmonic, first-harmonic winding loss is:

$P_{\mathrm{Cu}}=P_C\·{\left(\frac{\sqrt{3}{I}_1{U}_N}{S_N}\right)}^2---\left(2\right)$

Wherein: P _cuthe first-harmonic winding loss of transformer during for running,

P _cwinding loss during operation specified for transformer is the technical parameter of transformer,

I ₁for the effective value of primary side line current when transformer runs,

U _nfor the rated voltage of transformer primary side,

S _nfor transformer rated capacity;

Step 3: according to the measured data of the harmonic wave of transformer, calculates two parameters needed for estimation

${\mathrm{\α}}_1=\underset{h=2}{\mathrm{\Σ}}h\·{\mathrm{THD}}_h^2---\left(3\right)$

Wherein: α ₁for one of required parameter,

H is the number of times of harmonic wave,

THD _hfor the aberration rate of individual harmonic current,

${\mathrm{\α}}_2=\underset{h=2}{\mathrm{\Σ}}{\mathrm{THD}}_h^2---\left(4\right)$

Wherein: α ₂for one of required parameter,

H is the number of times of harmonic wave,

THD _hfor the aberration rate of each harmonic;

Step 4: the result obtained according to step above, estimation transformer harmonic loss,

ΔP＝P _Cu·α ₁+P _Fe·α ₂ (5)

Wherein: P _fethe first-harmonic core loss of transformer during for running,

P _cuthe first-harmonic winding loss of transformer during for running,

α ₁, α ₂for the parameter that step 3 calculates.

Embodiment 2

Below using the estimation of the transformer harmonic loss of reality as one embodiment of the present of invention, summary of the invention of the present invention is described further.

The parameter of real transformer is as follows: rated capacity is 50kVA, load loss is 1250W, open circuit loss is 150W, high pressure winding rated voltage is 20kV, low pressure winding rated voltage is 0.4kV, and high pressure winding rated current is 1.44A, and low pressure winding rated current is 72A, high pressure winding resistance is 121.5 Ω, and low pressure winding resistance is 0.03 Ω.The individual harmonic current component being recorded load by measurement mechanism is I ₁=70.2A, I ₅=12.312A, I ₇=7.776A, I ₁₁=3.168A, I ₁₃=2.016A, I ₁₇=1.08A, I ₁₉=0.7056A.The total losses of transformer (summation of first-harmonic loss and harmonic loss) calculated by existing method and Simulation Example compares, under curve fitting algorithm calculating harmonic condition, total losses of transformer is 1313W, under fair curve fitting algorithm calculating harmonic condition, the total losses of transformer are that under 1398W, IEEE/ANST C57.110 criterion calculation harmonic condition, total losses of transformer is 1670W.The evaluation method of the harmonic loss utilizing the present invention to propose, the estimated value of harmonic loss is 338.64W, and total loss is 1676W.The estimated value of evaluation method of the present invention, close to IEEE/ANST C57.110 criterion calculation result, has certain rationality, and than more efficient and practicality.

The above; be only the present invention's preferably embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.

Claims (1)

1. an evaluation method for transformer harmonic loss, is characterized in that, comprises the following steps:

Step 1: the core loss of analytical calculation transformer under first-harmonic, first-harmonic core loss is:

$P_{\mathrm{Fe}}=P_F\·{\left(\frac{U_1}{U_N}\right)}^2---\left(1\right)$

Wherein: P _fethe first-harmonic core loss of transformer during for running,

P _fcore loss during operation specified for transformer is the technical parameter of transformer,

U ₁for the effective value of side line voltage when transformer runs,

U _nfor the rated voltage of transformer primary side;

Step 2: the winding loss of analytical calculation transformer under first-harmonic, first-harmonic winding loss is:

$P_{\mathrm{Cu}}=P_C\·{\left(\frac{\sqrt{3}{I}_1{U}_N}{S_N}\right)}^2---\left(2\right)$

Wherein: P _cuthe first-harmonic winding loss of transformer during for running,

P _cwinding loss during operation specified for transformer is the technical parameter of transformer,

I ₁for the effective value of primary side line current when transformer runs,

U _nfor the rated voltage of transformer primary side,

S _nfor transformer rated capacity;

Step 3: according to the measured data of the harmonic wave of transformer, calculates two parameters needed for estimation;

${\mathrm{\α}}_1=\underset{h=2}{\mathrm{\Σ}}h\·{\mathrm{THD}}_h^2---\left(3\right)$

Wherein: α ₁for one of required parameter,

H is the number of times of harmonic wave,

THD _hfor the aberration rate of individual harmonic current,

${\mathrm{\α}}_2=\underset{h=2}{\mathrm{\Σ}}{\mathrm{THD}}_h^2---\left(4\right)$

Wherein: α ₂for one of required parameter,

H is the number of times of harmonic wave,

THD _hfor the aberration rate of each harmonic.

Step 4: the result obtained according to step above, estimation transformer harmonic loss;

ΔP＝P _Cu·α ₁+P _Fe·α ₂ (5)

Wherein: P _fethe first-harmonic core loss of transformer during for running,

P _cuthe first-harmonic winding loss of transformer during for running,

α ₁, α ₂for the parameter that step 3 calculates.