CN106093593A - Condenser type electric power equipment dielectric loss online test method and system - Google Patents

Abstract

The present invention relates to a kind of condenser type electric power equipment dielectric loss online test method and system, the voltage on the electric current on the earth lead of on-line measurement condenser type power equipment, and condenser type power equipment bus-bar potential transformer.The coefficient of each harmonic component of voltage and current is obtained by Fourier analysis.The coefficient calculations of each harmonic component according to voltage and current goes out the amplitude of each harmonic component of voltage and current.The amplitude of each harmonic component according to voltage and current, calculates equivalent capacity and the equivalent resistance of condenser type power equipment.Equivalent capacity and equivalent resistance according to condenser type power equipment are calculated dielectric loss angle tangent and export.Need not change original voltage measurement and the equipment of current measurement and means, need not accurate synchronization and also can accurately be calculated the dielectric loss of condenser type equipment, avoid the difficulty of voltage and current synchro measure, under voltage and current signal measures out of step conditions, also ensure that the accuracy of measurement of dielectric loss.

Description

Condenser type electric power equipment dielectric loss online test method and system

Technical field

The present invention relates to power equipment field tests, particularly relate to a kind of condenser type electric power equipment dielectric loss and examine online Survey method and system.

Background technology

Condenser type power equipment is the power equipment showing as electric capacity, such as sleeve pipe, current transformer, capacitor voltage mutual inductance Device CVT etc., it has a wide range of applications in power system, and quantity accounts for the 40%～50% of the total number of units of substation equipment.System Meter data shows, the main cause causing condenser type electrical equipment fault is insulating properties deteriorations, and insulation degradation master Show is that dielectric loss rises.Dielectric loss tan δ is the characteristic parameter of reflection insulation dielectric loss size, and it is only dependent upon The dielectric property of insulant, unrelated with the size of medium.Experience have shown that, for condenser type power equipment, measure it overall absolutely Edge dielectric dissipation factor can more delicately in discovering device expansionary local defect and apparatus insulated entirety make moist and deteriorate The defect such as rotten, thus it is particularly significant for the insulation status judging capacitance type equipment to measure tan δ.

In traditional prior art, in order to avoid offline inspection needs power failure and the problem that can not monitor continuously, at present The method generally using dielectric loss on-line checking (on-line monitoring or live detection), i.e. in the condition that power equipment is properly functioning Under, measure dielectric loss tan δ and capacitance C, but existing method needs synchro measure, there is the difficulty of accurate synchronization, the most very Easily bring measurement error.

The most how on the premise of not changing original voltage x current online detection instrument and method, from asynchronous measurement In the voltage and current signal of (there is certain time difference), obtain condenser type electric power equipment dielectric loss information accurately, for Judge that the insulation status of capacitance type equipment is significant.

Summary of the invention

Based on this, it is necessary to measuring under out of step conditions for voltage and current signal, existing dielectric loss measurement method is surveyed The amount inaccurate problem of result, it is provided that a kind of condenser type electric power equipment dielectric loss online test method and system.

A kind of condenser type electric power equipment dielectric loss online test method, comprises the following steps:

Electric current on the earth lead of on-line measurement condenser type power equipment, and described condenser type power equipment busbar voltage Voltage on transformer；

The coefficient of each harmonic component of described voltage and described electric current is obtained by Fourier analysis；

The coefficient calculations of each harmonic component according to described voltage and described electric current goes out described voltage and described electric current The amplitude of each harmonic component；

The amplitude of each harmonic component according to described voltage and described electric current, calculates the equivalent electric of condenser type power equipment Hold and equivalent resistance；

Equivalent capacity according to described condenser type power equipment and equivalent resistance are calculated dielectric loss angle tangent defeated Go out.

A kind of condenser type electric power equipment dielectric loss on-line detecting system, including:

Current/voltage detection module, the electric current on the earth lead of on-line measurement condenser type power equipment, and described electric capacity Voltage on formula power equipment bus-bar potential transformer；

Analyze module, obtained the coefficient of each harmonic component of described voltage and described electric current by Fourier analysis；

Harmonic component amplitude computing module, goes out according to the coefficient calculations of each harmonic component of described voltage and described electric current The amplitude of each harmonic component of described voltage and described electric current；

Equivalent capacity and equivalent resistance computing module, according to the width of each harmonic component of described voltage and described electric current Value, calculates equivalent capacity and the equivalent resistance of condenser type power equipment；

Dielectric loss angle tangent computing module, equivalent capacity and equivalent resistance according to described condenser type power equipment calculate Obtain dielectric loss angle tangent and export.

Above-mentioned condenser type electric power equipment dielectric loss online test method and system, there is harmonic wave in electrically-based system voltage Component, by measuring while the first-harmonic of condenser type power equipment voltage and current and harmonic wave, according to the width of each harmonic component Value is calculated equivalent capacity and the equivalent resistance of condenser type power equipment, it is not necessary to change original voltage measurement and current measurement Equipment and means, implement simple, safe and reliable, it is not necessary to accurate synchronization also can accurately be calculated the medium of condenser type equipment Loss, it is to avoid the difficulty of voltage and current synchro measure, also ensures that medium under voltage and current signal measures out of step conditions The accuracy of measurement of loss.

Accompanying drawing explanation

Fig. 1 is the flow chart of condenser type electric power equipment dielectric loss online test method in an embodiment；

Fig. 2 is the equivalent circuit diagram of condenser type power equipment；

Fig. 3 is the phasor diagram of voltage and current in condenser type power equipment；

Fig. 4 is the time domain beamformer of voltage and current in condenser type power equipment；

Fig. 5 is the structure chart of condenser type electric power equipment dielectric loss on-line detecting system in an embodiment.

Detailed description of the invention

For the ease of understanding the present invention, below with reference to relevant drawings, the present invention is described more fully.In accompanying drawing Give the preferred embodiment of the present invention.But, the present invention can realize in many different forms, however it is not limited to herein Described embodiment.On the contrary, providing the purpose of these embodiments is to make the understanding to the disclosure more saturating Thorough comprehensively.

Unless otherwise defined, all of technology used herein and scientific terminology and the technical field belonging to the present invention The implication that technical staff is generally understood that is identical.The term used the most in the description of the invention is intended merely to describe tool The purpose of the embodiment of body, it is not intended that in limiting the present invention.Term as used herein " or/and " include one or more phase Arbitrary and all of combination of the Listed Items closed.

A kind of condenser type electric power equipment dielectric loss online test method, as it is shown in figure 1, comprise the following steps:

Step S110: the electric current on the earth lead of on-line measurement condenser type power equipment, and condenser type power equipment is female Voltage on line voltage transformer.

Condenser type power equipment is the power equipment showing as electric capacity, such as sleeve pipe, current transformer, capacitor voltage mutual inductance Device CVT etc., it has a wide range of applications in power system, and quantity accounts for the 40%～50% of the total number of units of substation equipment.? Line is measured the electric current on the earth lead of condenser type power equipment and is typically to use electric current on the earth lead of condenser type power equipment Transformer measures, and the voltage on on-line measurement condenser type power equipment bus-bar potential transformer is typically the mother in transformer station Measure on line voltage transformer.

Step S120: obtained the coefficient of each harmonic component of voltage and current by Fourier analysis.

The electric current on the earth lead of condenser type power equipment and condenser type power equipment bus is obtained by step S110 After voltage on voltage transformer, calculated the coefficient of each harmonic component obtaining voltage and current by Fourier space.

Specifically, in one embodiment, step S120 includes step 122 and step 124.

Step 122: obtained the coefficient of each harmonic component of voltage by Fourier analysis.Particularly as follows:

$a_n=\frac{2}{N}\[U\left(0\right)+\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)cos\left(\frac{2\mathrm{\π}kn}{N}\right)\]$

$b_n=\frac{2}{N}\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)sin\left(\frac{2\mathrm{\π}kn}{N}\right)$

Step 124: obtained the coefficient of each harmonic component of electric current by Fourier analysis.Particularly as follows:

${a_n}^{\′}=\frac{2}{N}\[I\left(0\right)+\underset{k=1}{\overset{N-1}{\Σ}}I\left(k\right)cos\left(\frac{2\mathrm{\π}kn}{N}\right)\]$

${b_n}^{\′}=\frac{2}{N}\underset{k=1}{\overset{N-1}{\Σ}}I\left(k\right)sin\left(\frac{2\mathrm{\π}kn}{N}\right)$

Wherein, N is that time domain periodic signal one periodic sampling is counted, and I (k) and U (k) is the sampling of curtage kth time Value, n is odd number, a_n、b_nIt is respectively cosine coefficient and sinusoidal coefficients, a of the nth harmonic of voltage_n'、b_n' be respectively n time of electric current The cosine coefficient of harmonic wave and sinusoidal coefficients.

Step S130: go out each harmonic of voltage and current according to the coefficient calculations of each harmonic component of voltage and current The amplitude of component.

According to Fourier algorithm principle, after obtaining the coefficient of each harmonic component of voltage and current, can basis Respective formula calculates the amplitude of each harmonic component of voltage and current.

Specifically, in one embodiment, step S130 includes step 132 and step 134.

Step 132: go out the amplitude of each harmonic component of voltage according to the coefficient calculations of each harmonic component of voltage, tool Body is:

$U_n=\sqrt{a_n^2+b_n^2}$

Step 134: go out the amplitude of each harmonic component of electric current according to the coefficient calculations of each harmonic component of electric current, tool Body is:

$I_n=\sqrt{{a_n}^{\′2}+{b_n}^{\′2}}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nAmplitude for each harmonic component of electric current.

Step S140: according to the amplitude of each harmonic component of voltage and current, calculate the equivalence of condenser type power equipment Electric capacity and equivalent resistance.

As in figure 2 it is shown, be the equivalent circuit diagram of condenser type power equipment, wherein, C is that condenser type power equipment externally shows The equivalent capacity gone out, R is equivalent resistance,For being applied to the terminal voltage on condenser type power equipment,For flowing through condenser type electric power The total current of equipment,For flowing through the capacity current of electric capacity,For flowing through the current in resistance property of resistance.

According to the equivalent circuit of the condenser type equipment shown in Fig. 2, the amplitude of first-harmonic and each harmonic should meet:

$\left\{\begin{array}{c}\frac{\left|{\stackrel{\·}{U}}_1\right|}{\left|{\stackrel{\·}{I}}_1\right|}=\sqrt{R^2+{\left(\frac{1}{{\mathrm{\ω}}_{1}C}\right)}^2}\\ \frac{\left|{\stackrel{\·}{U}}_3\right|}{\left|{\stackrel{\·}{I}}_3\right|}=\sqrt{R^2+{\left(\frac{1}{{\mathrm{\ω}}_{3}C}\right)}^2}\\ \frac{\left|{\stackrel{\·}{U}}_5\right|}{\left|{\stackrel{\·}{I}}_5\right|}=\sqrt{R^2+{\left(\frac{1}{{\mathrm{\ω}}_{5}C}\right)}^2}\\ \mathrm{....}\end{array}\right.$

Particularly as follows:

$\frac{\left|U_n\right|}{\left|I_n\right|}=\sqrt{R^2+{\left(\frac{1}{w_{n}C}\right)}^2}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nFor the amplitude of each harmonic component of electric current, w_nFor n time The angular frequency of harmonic wave, n is odd number, and R is equivalent resistance, and C is equivalent capacity.

When n takes different value, any two (such as first-harmonic and the equation of triple-frequency harmonics) in these equations of simultaneous, Ji Keqiu Obtain equivalent resistance R and the value of equivalent capacity C of condenser type power equipment.

Step S150: equivalent capacity and equivalent resistance according to condenser type power equipment are calculated dielectric loss angle tangent And export.

As it is shown on figure 3, be the phasor diagram of voltage and current in condenser type power equipment.As shown in Figure 4, for condenser type electric power The time domain beamformer of voltage and current in equipment.Wherein, C is the equivalent capacity that condenser type power equipment externally shows, and R is Effect resistance,For being applied to the terminal voltage on condenser type power equipment,For flowing through the total current of condenser type power equipment,For Flow through the capacity current of electric capacity,For flowing through the current in resistance property of resistance,For power-factor angle, δ is dielectric loss angle.

According to Kirchhoff's law, should meet between each phasor:

$\stackrel{\·}{I}={\stackrel{\·}{I}}_R+{\stackrel{\·}{I}}_C=\frac{\stackrel{\·}{U}}{R}+\stackrel{\·}{U}\·j\mathrm{\ω}C$

Power-factor angleTherebetween should meet with dielectric loss angle δDielectric loss angle tangent tan δ's Computational methods are:

$tan\mathrm{\δ}=\frac{\left|{\stackrel{\·}{I}}_R\right|}{\left|{\stackrel{\·}{I}}_C\right|}=\frac{1}{\mathrm{\ω}RC}$

Particularly as follows:

$tan\mathrm{\δ}=\frac{1}{w_{n}RC}$

Wherein, δ is dielectric loss angle, w_nFor the angular frequency of nth harmonic, n is odd number, and R is equivalent resistance, and C is equivalent electric Hold.

So far, the on-line checking of dielectric loss under condenser type power equipment normal running (operation) conditions is i.e. completed.Export To dielectric loss angle tangent, can be specifically that output to display shows, it is also possible to be that output to memorizer stores.

Above-mentioned condenser type electric power equipment dielectric loss online test method, there is harmonic component in electrically-based system voltage, By measuring while the first-harmonic of condenser type power equipment voltage and current and harmonic wave, calculate according to the amplitude of each harmonic component Obtain equivalent capacity and the equivalent resistance of condenser type power equipment, it is not necessary to change the equipment of original voltage measurement and current measurement And means, implement simple, safe and reliable, it is not necessary to accurate synchronization also can accurately be calculated the dielectric loss of condenser type equipment, Avoid the difficulty of voltage and current synchro measure, under voltage and current signal measures out of step conditions, also ensure that dielectric loss Accuracy of measurement.

Present invention also offers a kind of condenser type electric power equipment dielectric loss on-line detecting system, as it is shown in figure 5, include electricity Stream voltage detection module 110, analysis module 120, harmonic component amplitude computing module 130, equivalent capacity and equivalent resistance calculate Module 140 and dielectric loss angle tangent computing module 150.

The current/voltage detection module 110 electric current on the earth lead of on-line measurement condenser type power equipment, Yi Ji electricity Voltage on appearance formula power equipment bus-bar potential transformer.

Analyze module 120 for being obtained the coefficient of each harmonic component of voltage and current by Fourier analysis.At it In in an embodiment, analyze module 120 and include voltage harmonic component calculation unit and current harmonics component calculation unit.

Specifically, voltage harmonic component calculation unit obtains the coefficient of voltage each harmonic component by Fourier analysis, Particularly as follows:

$a_n=\frac{2}{N}\[U\left(0\right)+\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)cos\left(\frac{2\mathrm{\π}kn}{N}\right)\]$

$b_n=\frac{2}{N}\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)sin\left(\frac{2\mathrm{\π}kn}{N}\right)$

Current harmonics component calculation unit obtains the coefficient of each harmonic component of electric current by Fourier analysis, specifically For:

${a_n}^{\′}=\frac{2}{N}\[I\left(0\right)+\underset{k=1}{\overset{N-1}{\Σ}}I\left(k\right)cos\left(\frac{2\mathrm{\π}kn}{N}\right)\]$

${b_n}^{\′}=\frac{2}{N}\underset{k=1}{\overset{N-1}{\Σ}}I\left(k\right)sin\left(\frac{2\mathrm{\π}kn}{N}\right)$

Wherein, N is that time domain periodic signal one periodic sampling is counted, and I (k) and U (k) is the sampling of curtage kth time Value, n is odd number, a_n、b_nIt is respectively cosine coefficient and sinusoidal coefficients, a of the nth harmonic of voltage_n'、b_n' be respectively n time of electric current The cosine coefficient of harmonic wave and sinusoidal coefficients.

Harmonic component amplitude computing module 130 goes out electricity for the coefficient calculations of each harmonic component according to voltage and current The amplitude of each harmonic component of pressure and electric current.Specifically, wherein in an embodiment, harmonic component amplitude computing module 130 include that voltage harmonic component amplitude computing unit and harmonic component crest meter calculate unit.

Specifically, voltage harmonic component amplitude computing unit goes out voltage according to the coefficient calculations of each harmonic component of voltage The amplitude of each harmonic component, particularly as follows:

$U_n=\sqrt{a_n^2+b_n^2}$

Current harmonics component amplitude computing unit goes out each time of electric current according to the coefficient calculations of each harmonic component of electric current The amplitude of harmonic component, particularly as follows:

$I_n=\sqrt{{a_n}^{\′2}+{b_n}^{\′2}}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nAmplitude for each harmonic component of electric current.

Equivalent capacity and equivalent resistance computing module 140 are used for the amplitude of each harmonic component according to voltage and current, Calculate equivalent capacity and the equivalent resistance of condenser type power equipment.Wherein in an embodiment, particularly as follows:

$\frac{\left|U_n\right|}{\left|I_n\right|}=\sqrt{R^2+{\left(\frac{1}{w_{n}C}\right)}^2}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nFor the amplitude of each harmonic component of electric current, w_nFor n time The angular frequency of harmonic wave, n is odd number, and R is equivalent resistance, and C is equivalent capacity.

When n takes different value, any two (such as first-harmonic and the equation of triple-frequency harmonics) in these equations of simultaneous, Ji Keqiu Obtain equivalent resistance R and the value of equivalent capacity C of condenser type power equipment.

Dielectric loss angle tangent computing module 150 is based on the equivalent capacity according to condenser type power equipment and equivalent resistance Calculation obtains dielectric loss angle tangent.Wherein in an embodiment, particularly as follows:

$tan\mathrm{\δ}=\frac{1}{w_{n}RC}$

Wherein, δ is dielectric loss angle, w_nFor the angular frequency of nth harmonic, n is odd number, and R is equivalent resistance, and C is equivalent electric Hold.

Above-mentioned condenser type electric power equipment dielectric loss on-line detecting system, there is harmonic component in electrically-based system voltage, By measuring while the first-harmonic of condenser type power equipment voltage and current and harmonic wave, calculate according to the amplitude of each harmonic component Obtain equivalent capacity and the equivalent resistance of condenser type power equipment, it is not necessary to change the equipment of original voltage measurement and current measurement And means, implement simple, safe and reliable, it is not necessary to accurate synchronization also can accurately be calculated the dielectric loss of condenser type equipment, Avoid the difficulty of voltage and current synchro measure, under voltage and current signal measures out of step conditions, also ensure that dielectric loss Accuracy of measurement.

Embodiment described above only have expressed the several embodiments of the present invention, and it describes more concrete and detailed, but also Can not therefore be construed as limiting the scope of the patent.It should be pointed out that, come for those of ordinary skill in the art Saying, without departing from the inventive concept of the premise, it is also possible to make some deformation and improvement, these broadly fall into the protection of the present invention Scope.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (10)

1. a condenser type electric power equipment dielectric loss online test method, it is characterised in that comprise the following steps:

Electric current on the earth lead of on-line measurement condenser type power equipment, and described condenser type power equipment busbar voltage mutual inductance Voltage on device；

The coefficient of each harmonic component of described voltage and described electric current is obtained by Fourier analysis；

The coefficient calculations of each harmonic component according to described voltage and described electric current goes out each time of described voltage and described electric current The amplitude of harmonic component；

The amplitude of each harmonic component according to described voltage and described electric current, calculate condenser type power equipment equivalent capacity and Equivalent resistance；

Equivalent capacity and equivalent resistance according to described condenser type power equipment are calculated dielectric loss angle tangent and export.

Condenser type electric power equipment dielectric loss online test method the most according to claim 1, it is characterised in that described logical Cross the coefficient that Fourier analysis obtains each harmonic component of described voltage and described electric current, including:

The coefficient of each harmonic component of described voltage is obtained by Fourier analysis, particularly as follows:

$a_n=\frac{2}{N}\[U\left(0\right)+\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)cos\left(\frac{2\mathrm{\π}kn}{N}\right)\]$

$b_n=\frac{2}{N}\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)sin\left(\frac{2\mathrm{\π}kn}{N}\right)$

The coefficient of each harmonic component of described electric current is obtained by Fourier analysis, particularly as follows:

${a_n}^{\′}=\frac{2}{N}\[I\left(0\right)+\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}I\left(k\right)\cos \left(\frac{2\mathrm{\π}kn}{N}\right)\]$

${b_n}^{\′}=\frac{2}{N}\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}I\left(k\right)\sin \left(\frac{2\mathrm{\π}kn}{N}\right)$

Wherein, N is that time domain periodic signal one periodic sampling is counted, and I (k) and U (k) is the sampled value of curtage kth time, n For odd number, a_n、b_nIt is respectively cosine coefficient and sinusoidal coefficients, a of the nth harmonic of voltage_n'、b_n' be respectively electric current nth harmonic Cosine coefficient and sinusoidal coefficients.

Condenser type electric power equipment dielectric loss online test method the most according to claim 2, it is characterised in that described The each harmonic going out described voltage and described electric current according to the coefficient calculations of each harmonic component of described voltage and described electric current divides The amplitude of amount, including:

The coefficient calculations of each harmonic component according to described voltage goes out the amplitude of each harmonic component of described voltage, specifically For:

$U_n=\sqrt{a_n^2+b_n^2}$

The coefficient calculations of each harmonic component according to described electric current goes out the amplitude of each harmonic component of described electric current, specifically For:

$I_n=\sqrt{{a_n}^{\′2}+{b_n}^{\′2}}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nAmplitude for each harmonic component of electric current.

Condenser type electric power equipment dielectric loss online test method the most according to claim 1, it is characterised in that described According to the amplitude of each harmonic component of described voltage and described electric current, calculate equivalent capacity and the equivalent electric of condenser type power equipment Resistance includes:

$\frac{\left|U_n\right|}{\left|I_n\right|}=\sqrt{R^2+{\left(\frac{1}{w_{n}C}\right)}^2}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nFor the amplitude of each harmonic component of electric current, w_nFor nth harmonic Angular frequency, n is odd number, and R is equivalent resistance, and C is equivalent capacity.

Condenser type electric power equipment dielectric loss online test method the most according to claim 1, it is characterised in that described Equivalent capacity and equivalent resistance according to described condenser type power equipment are calculated dielectric loss angle tangent and include:

$\tan \mathrm{\δ}=\frac{1}{w_{n}RC}$

Wherein, δ is dielectric loss angle, w_nFor the angular frequency of nth harmonic, n is odd number, and R is equivalent resistance, and C is equivalent capacity.

6. a condenser type electric power equipment dielectric loss on-line detecting system, it is characterised in that including:

Current/voltage detection module, the electric current on the earth lead of on-line measurement condenser type power equipment, and described capacitive battery Voltage on power equipment bus-bar potential transformer；

Analyze module, obtained the coefficient of each harmonic component of described voltage and described electric current by Fourier analysis；

Harmonic component amplitude computing module, goes out described according to the coefficient calculations of each harmonic component of described voltage and described electric current The amplitude of each harmonic component of voltage and described electric current；

Equivalent capacity and equivalent resistance computing module, according to the amplitude of each harmonic component of described voltage and described electric current, meter Calculate equivalent capacity and the equivalent resistance of condenser type power equipment；

Dielectric loss angle tangent computing module, equivalent capacity and equivalent resistance according to described condenser type power equipment are calculated Dielectric loss angle tangent also exports.

Condenser type electric power equipment dielectric loss on-line detecting system the most according to claim 6, it is characterised in that described point Analysis module includes:

Voltage harmonic component calculation unit, obtains the coefficient of each harmonic component of described voltage, specifically by Fourier analysis For:

$a_n=\frac{2}{N}\[U\left(0\right)+\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)cos\left(\frac{2\mathrm{\π}kn}{N}\right)\]$

$b_n=\frac{2}{N}\underset{k=1}{\overset{N-1}{\Σ}}U\left(k\right)sin\left(\frac{2\mathrm{\π}kn}{N}\right)$

Current harmonics component calculation unit, obtains the coefficient of each harmonic component of described electric current, specifically by Fourier analysis For:

${a_n}^{\′}=\frac{2}{N}\[I\left(0\right)+\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}I\left(k\right)\cos \left(\frac{2\mathrm{\π}kn}{N}\right)\]$

${b_n}^{\′}=\frac{2}{N}\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}I\left(k\right)\sin \left(\frac{2\mathrm{\π}kn}{N}\right)$

Wherein, N is that time domain periodic signal one periodic sampling is counted, and I (k) and U (k) is the sampled value of curtage kth time, n For odd number, a_n、b_nIt is respectively cosine coefficient and sinusoidal coefficients, a of the nth harmonic of voltage_n'、b_n' be respectively electric current nth harmonic Cosine coefficient and sinusoidal coefficients.

Condenser type electric power equipment dielectric loss on-line detecting system the most according to claim 7, it is characterised in that described humorous Wave component amplitude computing module includes:

Voltage harmonic component amplitude computing unit, goes out described voltage according to the coefficient calculations of each harmonic component of described voltage The amplitude of each harmonic component, particularly as follows:

$U_n=\sqrt{a_n^2+b_n^2}$

Current harmonics component amplitude computing unit, goes out described electric current according to the coefficient calculations of each harmonic component of described electric current The amplitude of each harmonic component, particularly as follows:

$I_n=\sqrt{{a_n}^{\′2}+{b_n}^{\′2}}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nAmplitude for each harmonic component of electric current.

Condenser type electric power equipment dielectric loss on-line detecting system the most according to claim 6, it is characterised in that described etc. Effect electric capacity and equivalent resistance computing module, according to the amplitude of each harmonic component of described voltage and described electric current, calculate condenser type The equivalent capacity of power equipment and equivalent resistance, including:

$\frac{\left|U_n\right|}{\left|I_n\right|}=\sqrt{R^2+{\left(\frac{1}{w_{n}C}\right)}^2}$

Wherein, U_nFor the amplitude of each harmonic component of voltage, I_nFor the amplitude of each harmonic component of electric current, w_nFor nth harmonic Angular frequency, n is odd number, and R is equivalent resistance, and C is equivalent capacity.

Condenser type electric power equipment dielectric loss on-line detecting system the most according to claim 6, it is characterised in that described Dielectric loss angle tangent computing module is calculated medium according to equivalent capacity and the equivalent resistance of described condenser type power equipment Loss angle tangent, including:

$\tan \mathrm{\δ}=\frac{1}{w_{n}RC}$

Wherein, δ is dielectric loss angle, w_nFor the angular frequency of nth harmonic, n is odd number, and R is equivalent resistance, and C is equivalent capacity.