CN203350323U - Capacitance-type voltage transformer applicable to high-voltage harmonic measurement - Google Patents

Abstract

The utility model relates to a capacitance-type voltage transformer applicable to high-voltage harmonic measurement. The capacitance-type voltage transformer applicable to high-voltage harmonic measurement is characterized in that a low-voltage capacitance branch of a capacitance voltage divider and an intermediate transformer branch of a capacitance-type voltage transformer are connected with one current transformer respectively. According to the capacitance-type voltage transformer applicable to high-voltage harmonic measurement of the utility model, two conventional current transformers are additionally arranged in a traditional capacitance-type voltage transformer; and by means of currents which are obtained through the measurement of the transformers, the magnitude and phase of high-voltage harmonic voltage can be calculated out. Thus, the capacitance-type voltage transformer applicable to high-voltage harmonic measurement of the utility model is advantageous in simple structure, easiness in realization, high precision in harmonic voltage measurement, resistance to the influence of a capacitance-type voltage transformer load as well as and high application value and market prospect in high-voltage harmonic voltage measurement occasions.

Description

A kind of capacitance type potential transformer that is applicable to the high voltage harmonic measure

Technical field

The utility model relates to a kind of capacitance type potential transformer, especially relates to a kind of capacitance type potential transformer that is applicable to the high voltage harmonic measure.

Background technology

The increasing voltage distortion problem of high-voltage electric power system that causes of the application of nonlinear-load in electric system is more and more serious.Power supply department and scientific research institution are measured in the urgent need to the voltage harmonic to high-voltage electric power system, to understand the voltage harmonic situation of high-pressure system, make harness of harmonic wave targetedly.

But in currently used high pressure harmonic measuring method and equipment, adopt the scheme of resistor dividing potential drop and capacitor dividing potential drop need to adopt special equipment, and these equipment volume are large, expensive.Capacitance type potential transformer is because of the advantage that its volume is little, lightweight, maintenance workload is few, electric field intensity nargin is large, insulating reliability is high; and dividing potential drop electric capacity can double as coupling condenser for radio frequency carrier channel, be widely used in even 35kV of 110kV() and voltage measurement, high frequency communication and the relay protection of above high voltage solidly earthed neutral system in.Thereby according to the actual fact, adopt capacitance type potential transformer to carry out the method that the high pressure harmonic measure is most convenient economy, but the internal resonance condition due to capacitance type potential transformer under harmonic condition is by destroyed, measure harmonic wave and larger error will occur, can't directly apply conventional capacitance type potential transformer and carry out the high pressure harmonic measure.

At present the frequency response characteristic of having researched and analysed capacitance type potential transformer is also arranged, after utilizing this frequency response characteristic to be revised capacitance type potential transformer double measurement voltage, derive on high-tension side voltage harmonic.But this scheme needs the frequency response characteristic of the various dissimilar capacitance type potential transformers of off-line analysis, need to know detailed construction and the element parameter of capacitance type potential transformer, and the frequency response characteristic under different loading conditions is also different, therefore this method realizes comparatively complicated, has limited its application.

Therefore, if can simply transform capacitance type potential transformer, design a kind of scheme that is applicable to the high pressure harmonic measure based on capacitance type potential transformer, can in the high-tension situation of measurement power frequency, provide high-precision high pressure harmonic measure simultaneously.Thereby, for realizing that the high pressure harmonic voltage measurement provides the scheme that a kind of cost performance is very high, have great practical value and the marketing prospect.

The utility model content

The utility model is mainly to solve the existing technical matters of prior art; Provide a kind of simple in structure, it is convenient to realize, measuring voltage harmonic wave precision is high, and be not subject to the impact of capacitance type potential transformer load, there is a kind of capacitance type potential transformer that is applicable to the high voltage harmonic measure of very high using value and marketing prospect in the occasion of high voltage harmonic voltage measurement.

A kind of capacitance type potential transformer that is applicable to the high voltage harmonic measure, is characterized in that, the current transformer of connecting respectively in the low-voltage capacitance branch road of the capacitive divider of capacitance type potential transformer and intermediate transformer branch road.

At above-mentioned a kind of capacitance type potential transformer that is applicable to the high voltage harmonic measure, the high-voltage capacitance of the capacitive divider of definition capacitance type potential transformer is high-voltage capacitance C _hand the low-voltage capacitance of capacitive divider is low-voltage capacitance C _l; The series compensation reactor of capacitance type potential transformer is series compensation reactor L _f; The intermediate transformer of capacitance type potential transformer is intermediate transformer T; At low-voltage capacitance C _lbranch road in the series connection one current transformer S1 after ground connection, in the branch road of intermediate transformer T the series connection one current transformer S2 after ground connection.

Therefore, the utlity model has following advantage: only need add the current transformer of two routines in the conventional condenser voltage transformer (VT), the electric current that utilizes these two mutual inductors to measure can calculate size and the phase place of high-pressure system harmonic voltage.The utility model is simple in structure, and it is convenient to realize, measuring voltage harmonic wave precision is high, and is not subject to the impact of capacitance type potential transformer load, in the occasion of high voltage harmonic voltage measurement, has very high using value and marketing prospect.

The accompanying drawing explanation

Fig. 1 is a kind of high voltage harmonic measure electrical block diagram based on capacitance type potential transformer of the present utility model.

Embodiment

Below by embodiment, and by reference to the accompanying drawings, the technical solution of the utility model is described in further detail.

Embodiment:

The structural drawing that accompanying drawing 1 is a kind of high voltage harmonic measure scheme based on capacitance type potential transformer.C in figure _hand C _lbe respectively high-voltage capacitance and the low-voltage capacitance of the capacitive divider of conventional capacitance type potential transformer; L _fseries compensation reactor for conventional capacitance type potential transformer; The intermediate transformer that T is conventional capacitance type potential transformer; Z _lload (not being the ingredient of capacitance type potential transformer) for capacitance type potential transformer.S1 and S2 are respectively the conventional series current mutual inductor that the utility model adds, and wherein S1 is connected on low-voltage capacitance C _lbranch road in, S2 is connected in the branch road of intermediate transformer T.Should be noted in order to reduce the insulating requirements to current transformer S1 and S2, current transformer S1 and S2 need respectively near low-voltage capacitance C simultaneously _lthe earth point of branch road and intermediate transformer T branch road.Here, it should be noted that: it is optional position in principle that S1 and S2 are connected in branch road, can not affect the size of measuring electric current, if but consider insulating requirements, the voltage that S1 and S2 are connected on difference is different, therefore, S1 is connected between the primary side and earth point of intermediate transformer, S2 is connected between low-voltage capacitance and earth point.

The secondary current measured according to current transformer S1 and no-load voltage ratio thereof can calculate low-voltage capacitance C _lthe current i of branch road _cL; The secondary current measured according to current transformer S2 and no-load voltage ratio thereof can calculate the current i of intermediate transformer T branch road _cT; According to Kirchhoff's current law (KCL), high-voltage capacitance C _hthe current i of branch road _cHmeet:

i _CH=i _CL+i _CT（1）

Utilize ripe Fourier Transform Technique, can decomposite respectively current i _cLand i _cHin harmonic current components:

$i_{\mathrm{CH}}=\sqrt{2}\·\underset{h=1}{\overset{n}{\mathrm{\Σ}}}(I_{\mathrm{CH}\left(h\right)}\·\sin (2\mathrm{\π}\·f\·h\·t+{\mathrm{\θ}}_{\mathrm{CH}\left(h\right)}))---\left(2\right)$

$i_{\mathrm{CL}}=\sqrt{2}\·\underset{h=1}{\overset{n}{\mathrm{\Σ}}}(I_{\mathrm{CL}\left(h\right)}\·\sin (2\mathrm{\π}\·f\·h\·t+{\mathrm{\θ}}_{\mathrm{CL}\left(h\right)}))---\left(3\right)$

Wherein: h is overtone order, and n is paid close attention to higher harmonics number of times (generally gets 40 times enough); F is power frequency, and China is 50Hz; T is the time; I _{cH (h)}and θ _{cH (h)}be respectively current i _cHin effective value and the phasing degree of h subharmonic; I _{cL (h)}and θ _{cL (h)}be respectively current i _cLin effective value and the phasing degree of h subharmonic.

By current i _cHand i _cLin the h subharmonic be written as respectively the phasor form:

${\stackrel{\·}{I}}_{\mathrm{CH}\left(h\right)}=I_{\mathrm{CH}\left(h\right)}\∠{\mathrm{\θ}}_{\mathrm{CH}\left(h\right)}---\left(4\right)$

${\stackrel{\·}{I}}_{\mathrm{CL}\left(h\right)}=I_{\mathrm{CL}\left(h\right)}\∠{\mathrm{\θ}}_{\mathrm{CL}\left(h\right)}---\left(5\right)$

Need the high-pressure system voltage u measured _sthe h subharmonic can calculate by following formula:

${\stackrel{\·}{U}}_{S\left(h\right)}={\stackrel{\·}{I}}_{\mathrm{CL}\left(h\right)}\·\frac{1}{j\·2\mathrm{\π}\·f\·h{\·C}_L}+{\stackrel{\·}{I}}_{\mathrm{CH}\left(h\right)}\·\frac{1}{j\·2\mathrm{\π}\·f\·h\·C_H}---\left(6\right)$

To all subharmonic (h=1,2 ..., n) all carry out the calculating shown in formula (6), can calculate high-pressure system voltage u _seach harmonic voltage, these voltages are to carry out the needed value of frequency analysis.

The utility model seals in respectively the conventional current mutual inductor in the low-voltage capacitance branch road of the capacitive divider of conventional capacitance type potential transformer and intermediate transformer branch road, the low-voltage capacitance branch road that utilization measures and the electric current of intermediate transformer branch road, in conjunction with high pressure and the low-voltage capacitance value of capacitive divider, can calculate the harmonic content of high-pressure system voltage.High voltage harmonic measure scheme based on capacitance type potential transformer of the present utility model only need simply be improved on the basis of conventional capacitance type potential transformer, realize simple, for the accurate measurement that realizes the high pressure harmonic voltage provides important technological means, there is very high practical value and wide marketing application prospect.

Above embodiment is only for illustration of the utility model, but not to restriction of the present utility model, person skilled in the relevant technique, in the situation that do not break away from spirit and scope of the present utility model, can also make various conversion or modification, therefore, within all technical schemes that are equal to also should belong to category of the present utility model, should be limited by each claim.

Specific embodiment described herein is only to the explanation for example of the utility model spirit.The utility model person of ordinary skill in the field can make various modifications or supplements or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present utility model or surmount the defined scope of appended claims.

Claims (2)

1. a capacitance type potential transformer that is applicable to the high voltage harmonic measure, is characterized in that, the current transformer of connecting respectively in the low-voltage capacitance branch road of the capacitive divider of capacitance type potential transformer and intermediate transformer branch road.

2. a kind of capacitance type potential transformer that is applicable to the high voltage harmonic measure according to claim 1, is characterized in that, the high-voltage capacitance of the capacitive divider of definition capacitance type potential transformer is high-voltage capacitance C _hand the low-voltage capacitance of capacitive divider is low-voltage capacitance C _l; The series compensation reactor of capacitance type potential transformer is series compensation reactor L _f; The intermediate transformer of capacitance type potential transformer is intermediate transformer T; At low-voltage capacitance C _lbranch road in the series connection one current transformer S1 after ground connection, in the branch road of intermediate transformer T the series connection one current transformer S2 after ground connection.