CN104198798A - Method for measuring resonance of fault capacitive current of petersen coil device - Google Patents

Abstract

The invention relates to method for measuring resonance of a fault capacitive current of a petersen coil device. The method includes the following specific steps: an adjustable reactance L is in series connection with the low pressure side of a zero-sequence voltage transformer internally disposed in a petersen coil; a current signal with a constant frequency is injected into a grid; inductive reactance is adjusted to be equal to line-to-ground capacitance, a so-called series resonance is generated on a circuit; a current flowing through a loop is resistive with a maximum amplitude. The place of a maximum current is determined to be a resonance point, the inductive reactance of which is system capacitive reactance, and the capacitive current of the system is calculated. The provided petersen coil device has the problems of too large error, too much tuning and the like in capacitive current measurement when the petersen coil is running, and with a voltage and current transformer installed in the central point of the petersen coil, high voltage and high current are converted to low voltage and low current, and capacitive currents are measured in real time with the introduction of a computer control system.

Description

A kind of resonance measuring method for arc suppression coil device fault capacitance current

Technical field

The invention belongs to control panel field, especially a kind of resonance measuring method for arc suppression coil device fault capacitance current.

Background technology

In China, Neutral Grounding Modes of Power System is divided into two classes: directly ground connection (containing low resistance grounding) and not direct ground connection (containing through grounding through arc).Generally, 110kV and above system neutral adopt direct grounding way, and 66kV and following system neutral adopt not direct grounding way.

Taking 110kV and following distribution as main body, wherein the earthing mode of 35kV system mostly adopts neutral by arc extinction coil grounding.Under this earthing mode, in the time of system generation singlephase earth fault, earth point will pass through whole capacitive earth currents of ground path corresponding voltage grade electrical network.If this capacitance current is quite large, will produce intermittent electric arc at earth point, cause superpotential, thereby healthy phases voltage-to-ground is greatly increased.Under the effect of arcing ground over-voltage, may cause insulation damages, cause the ground short circuit of or multiple spot at 2, make fault spread.Arc suppression coil is generally installed between transformer neutral point and ground, and its object is exactly the capacity current while utilizing the inductance current compensation of ground fault of arc suppression coil, and earth-fault current is reduced, so that blow-out automatically, ensures to continue power supply, improves reliability.

In real work, arc suppression coil should be determined capacity according to compensated capacitance current numerical value, and will be adjusted to a certain gear, makes its inductance value depart from the capacitance current value that it compensates, to avoid occurring resonance.Capacity Selection is improper or deviation value is excessive or too small, all can affect the serviceable life of arc suppression coil, even critical power network safety operation.If inductive current equals capacitance current for full compensation after compensation, can cause series resonance, make the very high voltage of arc suppression coil impression; After compensation, to be less than capacitance current be under-compensation to inductive current, can there is neutral-point displacement and jeopardize insulation, therefore in reality for guaranteeing electricity net safety stable, the often over-compensation modes of taking more, i.e. the rear inductive current of compensation is greater than capacitance current.

If the calculating of arc suppression coil gear is manually carried out by the person of regulation and control, easily there is deviation in required time length and result, and not only efficiency is low, more can bring uncertain factor to power network safety operation.

Summary of the invention

The object of the invention is to overcome prior art deficiency, a kind of arc suppression coil gear computing velocity speed, resonance measuring method for arc suppression coil device fault capacitance current that accuracy is higher of improving is provided.

The technical solution used in the present invention is:

A kind of resonance measuring method for arc suppression coil device fault capacitance current, specifically: at a regulative reactance L ' of low-pressure side series connection of the built-in zero sequential potential transformer of arc suppression coil, and inject the current signal of a constant frequency to electrical network, adjusting induction reactance makes it equal line-to-ground capacitive reactance, so-called series resonance on circuit for generating, the electric current flowing through in loop is resistive, and it is maximum that amplitude reaches., judge that electric current maximum is tuning-points, take out the induction reactance of this point, be system capacitive reactance, calculate thus system capacitive current.

And described resonance measuring method calculates and calculates by following formula:

$C_{\mathrm{sum}}=\frac{{{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2({l_2}^{\text{'}}-{l_1}^{;})}=\frac{{{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2{k}^2({L_2}^{\text{'}}-{L_1}^{\text{'}})}$

$I_C=\frac{\mathrm{\ω}({{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2)U_{\mathrm{\Φ}}}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2({l_2}^{\text{'}}-{l_1}^{\text{'}})}=\frac{\mathrm{\ω}({{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2)U_{\mathrm{\Φ}}}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2{k}^2({L_2}^{\text{'}}-{L_1}^{\text{'}})}$

When regulating a reactance value L1 ', will return to relevant voltage, the current signal that makes its injection and the voltage signal phase angle difference of returning are 0 resonant condition to occur, the frequency now recording is the resonance frequency omega 1 of system.When regulating another reactance value L1 ', can obtain again another resonance frequency omega 2, thereby calculate by the resonance frequency of twice acquisition, obtain direct earth capacitance and fault capacitance current, wherein ω, U are respectively frequency and the phase voltage of system, can calculate ground current.

Advantage of the present invention and good effect are:

1, arc suppression coil device provided by the invention is owing to existing capacitance current measurement bigger error, the tuning problem such as too much arc suppression coil in service, the present invention is at arc suppression coil neutral point installing voltage transformer (VT) summation current transformer, be low-voltage, little electric current by high voltage once, large current conversion, Import computer control system, measures in real time to capacitance current.

Brief description of the drawings:

Fig. 1 measures capacitance current schematic diagram in the present invention.

Embodiment:

Below by accompanying drawing, the invention will be further described in conjunction with specific embodiments, and following examples are descriptive, is not determinate, can not limit protection scope of the present invention with this.

A kind of resonance measuring method for arc suppression coil device fault capacitance current, the method is measured fault capacitance current for the in service of arc suppression coil in distribution line, its thinking is mainly a regulative reactance L ' of low-pressure side series connection of the zero sequential potential transformer built-in at arc suppression coil, and inject the current signal of a constant frequency to electrical network, adjusting induction reactance makes it equal line-to-ground capacitive reactance (XL=XC), so-called series resonance on circuit for generating, the electric current flowing through in loop is resistive, and it is maximum that amplitude reaches.Judging that electric current maximum is tuning-points, take out the induction reactance of this point, is system capacitive reactance, calculates thus system capacitive current, and its circuit theory diagrams as shown in Figure 1.

In figure, L ' is the regulative reactance of series voltage mutual inductor low-pressure side, and Is is Injection Current source.Ignore the reactance on the built-in former and deputy limit of voltage transformer (VT) of coil, can obtain equivalent circuit diagram.Regulate reactance L ', according to the condition of equivalent circuit generation resonant condition.

When regulating a reactance value L1 ', will return to relevant voltage, the current signal that makes its injection and the voltage signal phase angle difference of returning are 0 resonant condition to occur, the frequency now recording is the resonance frequency omega 1 of system.When regulating another reactance value L1 ', can obtain again another resonance frequency omega 2, thereby calculate by the resonance frequency of twice acquisition, obtain direct earth capacitance and fault capacitance current, concrete formula is as follows:

$C_{\mathrm{sum}}=\frac{{{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2({l_2}^{\text{'}}-{l_1}^{;})}=\frac{{{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2{k}^2({L_2}^{\text{'}}-{L_1}^{\text{'}})}$

$I_C=\frac{\mathrm{\ω}({{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2)U_{\mathrm{\Φ}}}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2({l_2}^{\text{'}}-{l_1}^{\text{'}})}=\frac{\mathrm{\ω}({{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2)U_{\mathrm{\Φ}}}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2{k}^2({L_2}^{\text{'}}-{L_1}^{\text{'}})}$

Wherein ω, U are respectively frequency and the phase voltage of system, can calculate ground current.

In this way, reactance value changes institute and causes the amplitude of variation of electric voltage displacement little profit, can not bring interference to system stability, and wave filter is in addition more can keeping system reliable and stable.

Although disclose for the purpose of illustration embodiments of the invention and accompanying drawing, but it will be appreciated by those skilled in the art that: not departing from the spirit and scope of the present invention and claims, various replacements, variation and amendment are all possible, therefore, scope of the present invention is not limited to embodiment and the disclosed content of accompanying drawing.

Claims (2)

1. the resonance measuring method for arc suppression coil device fault capacitance current, it is characterized in that: at a regulative reactance L ' of low-pressure side series connection of the built-in zero sequential potential transformer of arc suppression coil, and inject the current signal of a constant frequency to electrical network, adjusting induction reactance makes it equal line-to-ground capacitive reactance, so-called series resonance on circuit for generating, the electric current flowing through in loop is resistive, and it is maximum that amplitude reaches., judge that electric current maximum is tuning-points, take out the induction reactance of this point, be system capacitive reactance, calculate thus system capacitive current.

2. the resonance measuring method for arc suppression coil device fault capacitance current according to claim 1, is characterized in that: described resonance measuring method calculates and calculates by following formula:

$C_{\mathrm{sum}}=\frac{{{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2({l_2}^{\text{'}}-{l_1}^{;})}=\frac{{{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2{k}^2({L_2}^{\text{'}}-{L_1}^{\text{'}})}$

$I_C=\frac{\mathrm{\ω}({{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2)U_{\mathrm{\Φ}}}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2({l_2}^{\text{'}}-{l_1}^{\text{'}})}=\frac{\mathrm{\ω}({{\mathrm{\ω}}_1}^2-{{\mathrm{\ω}}_2}^2)U_{\mathrm{\Φ}}}{{{\mathrm{\ω}}_1}^2{{\mathrm{\ω}}_2}^2{k}^2({L_2}^{\text{'}}-{L_1}^{\text{'}})}$

When regulating a reactance value L1 ', will return to relevant voltage, the current signal that makes its injection and the voltage signal phase angle difference of returning are 0 resonant condition to occur, the frequency now recording is the resonance frequency omega 1 of system; When regulating another reactance value L1 ', can obtain again another resonance frequency omega 2, thereby calculate by the resonance frequency of twice acquisition, obtain direct earth capacitance and fault capacitance current, wherein ω, U are respectively frequency and the phase voltage of system, can calculate ground current.