CN104865452A - Harmonic-component-based anti-interference capacitance measurement method for untransposed transmission line - Google Patents

Abstract

The invention discloses a harmonic-component-based anti-interference capacitance measurement method for an untransposed transmission line. Big enough third harmonic is generated in a measurement line through a saturable transformer, a GPS-based synchronous measuring unit is utilized to measure the triphase voltage and the triphase current at the head end and the tail end of the line, and the Hanning windowed FFT interpolation algorithm is adopted to treat the voltage and the current at the head end and the tail end of the line so as to obtain triple harmonic components of the triphase voltage and the triphase current at the head end and the tail end. Meanwhile, in consideration of unequal mutual parameters between two phases of the untransposed transmission line, the harmonic components are utilized to solve the self-admittance and interphase transadmittance parameters of all phases based on a lumped parameter model of the transmission line, and all-sequence capacitance parameters are obtained. The harmonic-component-based anti-interference capacitance measurement method eliminates influence on capacitance measurement of a measured line from power frequency interference of a nearby charged operation line, greatly improves the measurement accuracy and can meet the demands of actual project measurement.

Description

Based on the not transposed transmission line Xc interference detecting method of harmonic component

Technical field

The present invention relates to a kind of transmission line of electricity capacitance parameter accurate measurement method, content is the not transposed transmission line Xc interference detecting method based on harmonic component.

Background technology

Transmission line parameter is the important foundation data of Load flow calculation in electric system, power attenuation calculating, short circuit calculation, fault analysis and relay protection setting calculation.Not line parameter circuit value accurately, just cannot ensure the accuracy of above-mentioned calculating, and then may cause being failure to actuate or misoperation of protective relaying device and other aut.eq..Therefore, the normal operation of parameter to electric system obtaining transmission line of electricity exactly has very important meaning.

Along with the develop rapidly of electric system in recent years, because transmission of electricity corridor is crowded and overhead line structures expenditure of construction is high, the quantity of coupling power transmission line constantly increases, and makes the electromagnetic interference (EMI) between circuit further serious, brings very large difficulty to accurately measurement transmission line parameter.

At present, about transmission line of electricity calculating and measure achieved many achievements.The main method obtaining transmission line parameter comprises theoretical calculation method and field survey method.And change because soil resistivity greatly can change along with the geographical environmental condition below circuit, and computing method have ignored the impact of electromagnetic interference (EMI) on line parameter circuit value of weather and neighbouring circuit, especially on the impact of Zero sequence parameter.Therefore, need should carry out field survey to transmission line parameter.

But in actual measurement, below 200km transmission line of electricity mostly is the circuit that do not replace, the interference causing not replacing between circuit strengthens, because the induced voltage phasor of the three-phase line of other circuits that do not replace neighbouring in measuring circuit and non-vanishing.Especially under strong interference environment, neighbouring coupling circuit can induce larger power-frequency voltage in measuring circuit, i.e. Hz noise, comes with very large error to circuit power frequency parameter measuring.

Because interference voltage can change along with neighbouring Line Flow change, and the interference current caused by interference voltage cannot be measured, and therefore, in reality, interference voltage and interference current being included in computing formula is be difficult to realize.In the capacitance parameter actual measurement of the overwhelming majority, all have employed the measuring method not considering to disturb, cause measuring error comparatively large, Practical Project measurement demand cannot be met.

Summary of the invention

The present invention mainly solves and brings the drawback causing measuring error larger compared with disturbance of industry frequency due to the neighbouring circuit that do not replace existing for prior art; Provide a kind of not transposed transmission line Xc interference detecting method based on harmonic component, the method can eliminate the impact that Hz noise brings, accurately measure the capacitance parameter that circuit is all, comprise the parameters such as the mutual capacitance between zero sequence electric capacity, positive sequence electric capacity, negative phase-sequence electric capacity and different sequence.

Above-mentioned technical matters of the present invention is mainly solved by following technical proposals:

Based on the not transposed transmission line Xc interference detecting method of harmonic component, it is characterized in that, definition transmission line of electricity is made up of the circuit b of the test line a had a power failure and charging operation, and every loop line road is formed by three-phase line.Measuring process comprises:

Step 1, by step-up transformer (transformer that unloaded lower energy is saturated), applies three-phase main-frequency voltage at measuring circuit a head end, circuit a end three-phase open circuit (end current is 0).Utilize the three-phase voltage based on the synchronous measuring apparatus synchronous acquisition circuit a head end of GPS technology the three-phase voltage of end with the three-phase current of head end

Step 2, exchanges the wiring position of A phase and B phase and test line in head end three-phase supply, utilizes the three-phase voltage of the synchronous measuring apparatus synchronous acquisition circuit a head end based on GPS technology the three-phase voltage of end with the three-phase current of head end

Step 3, exchanges the wiring position of A phase and C phase and test line in head end three-phase supply, utilizes the three-phase voltage of the synchronous measuring apparatus synchronous acquisition circuit a head end based on GPS technology the three-phase voltage of end with the three-phase current of head end

Step 4, to three-phase voltage and the three-phase current data of the three groups of head and ends obtained under step 1, step 2 and step 3 three kinds of independent metering systems, adopt FFT (Fast Fourier Transform (FFT)) the interpolation algorithm process adding Hanning window, obtain the three-phase voltage of three groups of head and ends and the third-harmonic component of three-phase current, comprising:

Under first time measurement, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Under second time is measured, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Under third time measurement, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Step 5, by third harmonic voltage and the triple harmonic current of above three groups of circuit head and ends, and circuit model, can obtain:

$\left[\begin{array}{ccc}{\stackrel{\·}{I}}_{aS3}^1& {\stackrel{\·}{I}}_{aS3}^2& {\stackrel{\·}{I}}_{aS3}^3\\ {\stackrel{\·}{I}}_{bS3}^1& {\stackrel{\·}{I}}_{bS3}^2& {\stackrel{\·}{I}}_{bS3}^3\\ {\stackrel{\·}{I}}_{cS3}^1& {\stackrel{\·}{I}}_{cS3}^2& {\stackrel{\·}{I}}_{cS3}^3\end{array}\right]=\frac{1}{2}{Y}_3\left[\begin{array}{ccc}{\stackrel{\·}{U}}_{aS3}^1+{\stackrel{\·}{U}}_{aM3}^1& {\stackrel{\·}{U}}_{aS3}^2+{\stackrel{\·}{U}}_{aM3}^2& {\stackrel{\·}{U}}_{aS3}^3+{\stackrel{\·}{U}}_{aM3}^3\\ {\stackrel{\·}{U}}_{bS3}^1+{\stackrel{\·}{U}}_{bM3}^1& {\stackrel{\·}{U}}_{bS3}^2+{\stackrel{\·}{U}}_{bM3}^2& {\stackrel{\·}{U}}_{bS3}^3+{\stackrel{\·}{U}}_{bM3}^3\\ {\stackrel{\·}{U}}_{cS3}^1+{\stackrel{\·}{U}}_{cM3}^1& {\stackrel{\·}{U}}_{cS3}^3+{\stackrel{\·}{U}}_{cM3}^3& {\stackrel{\·}{U}}_{cS3}^3+{\stackrel{\·}{U}}_{cM3}^3\end{array}\right]$

Wherein, Y ₃for the admittance matrix of circuit under third harmonic frequencies:

$Y_3=\left[\begin{array}{ccc}{Y}_{a3}& Y_{ab3}& Y_{ac3}\\ Y_{ab3}& Y_{b3}& Y_{bc3}\\ Y_{ac3}& Y_{bc3}& Y_{c3}\end{array}\right]$

Y _a3for the admittance under measured circuit A phase third harmonic frequencies, Y _b3for the admittance under measured circuit B phase third harmonic frequencies, Y _c3for the admittance under measured circuit C phase third harmonic frequencies, Y _ab3, Y _ac3, Y _bc3for the transadmittance under third harmonic frequencies between the different two-phase of measured circuit.

Solve an equation and try to achieve admittance matrix Y ₃.

Step 6, is converted to the sequence capacitance matrix under fundamental frequency, because line conductance parameter is minimum, therefore ignores by the phase admittance matrix under measured circuit third harmonic frequencies.Simultaneously divided by line length l, obtain the capacitance parameter of every km, comprise zero sequence electric capacity C ₀, positive sequence electric capacity C ₁, negative phase-sequence electric capacity C ₂, and different two sequences between mutual capacitance C ₀₁, C ₀₂, C ₁₀, C ₁₂, C ₂₀, C ₂₁.

In above formula, l is line length, and w=2 π f, f are mains frequency.Technical scheme provided by the present invention proposes the not transposed transmission line Xc interference detecting method based on harmonic component, by the third harmonic that saturation transformer under zero load produces in measured circuit, utilize the three-phase voltage based on the synchronous measuring apparatus measuring circuit head and end of GPS technology and three-phase current, adopt the FFT interpolation algorithm adding Hanning window to the voltage and current process of circuit head and end, obtain the three-phase voltage of head and end and the third-harmonic component of three-phase current.Consider that the mutual parameter between circuit two-phase that do not replace is unequal simultaneously, utilize harmonic component to solve the self-admittance of all phases and alternate transadmittance, and then obtain institute's capacitance parameter in order of measured circuit.

The present invention has following characteristics:

(1) utilize harmonic component to calculate, " turned bane into boon " by harmonic wave, the neighbouring circuit Hz noise of filtering, on the impact of measuring, drastically increases the measuring accuracy of line capacitance;

(2) utilize power supply commutation to pressurize respectively and obtain three groups of measurement data, it is very convenient to operate;

(3) utilize voltage and the three-phase current data of circuit three-phase, can disposablely measure orderly capacitance parameter;

(4) be not only applicable near the situation of line-hit once, the situation having multi circuit transmission lines to disturb near being also applicable to;

(5) accuracy that the accurate measurement that realize transmission line of electricity capacitance parameter of the inventive method under strong interference environment, raising relay protection of power system are adjusted and raising power supply reliability have positive role.

Accompanying drawing explanation

Accompanying drawing 1 is that UHV (ultra-high voltage) is with tower four times/double back bipolar transmission line road equivalent schematic.

Accompanying drawing 2 is the distributed parameter model schematic diagram of UHV (ultra-high voltage) transmission line with four-circuit on single tower.

Accompanying drawing 3 is UHV (ultra-high voltage) transmission line with four-circuit on single tower locus floor map.

Embodiment

Below by embodiment, and by reference to the accompanying drawings, technical scheme of the present invention is described in further detail.

Embodiment:

Technical solution of the present invention is described in detail below in conjunction with drawings and Examples.

1., based on the not transposed transmission line Xc interferometry of harmonic component, embodiment comprises the following steps:

Step 1, selects measured dead line a, the circuit b of neighbouring charging operation.

Shown in Figure 1, by step-up transformer (unloaded lower energy saturation transformer), apply three-phase main-frequency voltage at measured circuit a head end, circuit a terminal open circuit (end current is 0).Utilize the time service gain-of-function error of GPS to be less than the time reference of 1 microsecond, under gps time is synchronous, embodiment gathers the three-phase voltage of circuit a head end simultaneously the three-phase voltage of end with the three-phase current of head end and in the mode of file, measurement data is preserved.

Step 2, exchanges the wiring position of A phase and B phase and circuit in head end three-phase supply, utilizes the time service gain-of-function error of GPS to be less than the time reference of 1 microsecond, and under gps time is synchronous, embodiment gathers the three-phase voltage of circuit a head end simultaneously the three-phase voltage of end with the three-phase current of head end and in the mode of file, measurement data is preserved.

Step 3, exchanges the wiring position of A phase and C phase and circuit in head end three-phase supply, utilizes the time service gain-of-function error of GPS to be less than the time reference of 1 microsecond, and under gps time is synchronous, embodiment gathers the three-phase voltage of circuit a head end simultaneously the three-phase voltage of end with the three-phase current of head end

Step 4, the file that gained measurement data under three kinds of independent metering systems is preserved is aggregated in a computing machine, under each independent metering system, the measurement data of some time interior (such as between 0.2 second to 0.4 second) after head and end equal line taking road pressurization, add the FFT interpolation algorithm process of Hanning window, obtain the three-phase voltage of three groups of head and ends and the third-harmonic component of three-phase current, comprising:

Under first time measurement, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Under second time is measured, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Under third time measurement, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Voltage unit in the present invention is all volt, and current unit is all ampere.

The FFT interpolation algorithm adding Hanning window is prior art, and it will not go into details in the present invention.

Step 5, circuit model shown in Figure 2, substitutes into formula (A1) by the third harmonic voltage of three groups of circuit head and ends and triple harmonic current,

$\left[\begin{array}{ccc}{\stackrel{\·}{I}}_{aS3}^1& {\stackrel{\·}{I}}_{aS3}^2& {\stackrel{\·}{I}}_{aS3}^3\\ {\stackrel{\·}{I}}_{bS3}^1& {\stackrel{\·}{I}}_{bS3}^2& {\stackrel{\·}{I}}_{bS3}^3\\ {\stackrel{\·}{I}}_{cS3}^1& {\stackrel{\·}{I}}_{cS3}^2& {\stackrel{\·}{I}}_{cS3}^3\end{array}\right]=\frac{1}{2}{Y}_3\left[\begin{array}{ccc}{\stackrel{\·}{U}}_{aS3}^1+{\stackrel{\·}{U}}_{aM3}^1& {\stackrel{\·}{U}}_{aS3}^2+{\stackrel{\·}{U}}_{aM3}^2& {\stackrel{\·}{U}}_{aS3}^3+{\stackrel{\·}{U}}_{aM3}^3\\ {\stackrel{\·}{U}}_{bS3}^1+{\stackrel{\·}{U}}_{bM3}^1& {\stackrel{\·}{U}}_{bS3}^2+{\stackrel{\·}{U}}_{bM3}^2& {\stackrel{\·}{U}}_{bS3}^3+{\stackrel{\·}{U}}_{bM3}^3\\ {\stackrel{\·}{U}}_{cS3}^1+{\stackrel{\·}{U}}_{cM3}^1& {\stackrel{\·}{U}}_{cS3}^3+{\stackrel{\·}{U}}_{cM3}^3& {\stackrel{\·}{U}}_{cS3}^3+{\stackrel{\·}{U}}_{cM3}^3\end{array}\right]$

$\left(A1\right)$

Solve formula (A1) obtain circuit third harmonic frequencies under admittance matrix Y ₃.

Wherein:

$Y_3=\left[\begin{array}{ccc}{Y}_{a3}& Y_{ab3}& Y_{ac3}\\ Y_{ab3}& Y_{b3}& Y_{bc3}\\ Y_{ac3}& Y_{bc3}& Y_{c3}\end{array}\right]---\left(A2\right)$

Step 6, by Y ₃substitution formula (A3)

Solve and obtain all capacitance parameters, comprise zero sequence electric capacity C ₀, positive sequence electric capacity C ₁, negative phase-sequence electric capacity C ₂, and different two sequences between mutual capacitance C ₀₁, C ₀₂, C ₁₀, C ₁₂, C ₂₀, C ₂₁.Capacitance parameter unit is nF/km.

For illustrating that for the purpose of effect of the present invention, for common-tower double-return 220kV coupling power transmission line a, b, transmission line of electricity a is measured circuit, and transmission line of electricity b is the circuit of charging operation, the distribution of its locus is see Fig. 3.

The theoretical capacitance parameter of transmission line of electricity a is as follows.

$\left[\begin{array}{ccc}{C}_0& C_{01}& C_{02}\\ C_{10}& C_1& C_{12}\\ C_{20}& C_{21}& C_2\end{array}\right]=\left[\begin{array}{ccc}6.4099& 0.0450+j0.3551& 0.0450-j0.3551\\ 0.0450-j0.3551& 9.3958& -0.3063-j0.3857\\ 0.0450+j0.3551& -0.3063+j0.3857& 9.3958\end{array}\right]---\left(A4\right)$

Additional three-phase voltage is 10kV, and when circuit a length is 50km, the capacitance parameter that the classic method measurement utilizing fundametal compoment to carry out calculating obtains is

$\left[\begin{array}{ccc}7.4154& -2.5044+j0.8425& -205044-j0.8425\\ -2.5044-j0.8425& 10.927& 0.1618+j1.8199\\ -2.5044+j0.8425& 0.1618+j1.8199& 10.927\end{array}\right]---\left(A5\right)$

Additional three-phase voltage is 10kV, and when circuit a length is 50km, the inventive method measurement result is

$\left[\begin{array}{ccc}6.4379& 0.0448+j0.3539& 0.0448-j0.3539\\ 0.0448-j0.3539& 9.4269& -0.3075-j0.3875\\ 0.0448+j0.3539& -0.3075+j0.3875& 9.4269\end{array}\right]---\left(A6\right)$

From above result of calculation, the measuring error of classic method sequence mutual capacitance is very large, and zero sequence, positive sequence electric capacity (negative phase-sequence electric capacity equals positive sequence electric capacity) measuring error are also larger.And the inventive method can accurately measure orderly capacitance parameter.

Table 1 provides the circuit zero sequence electric capacity, positive sequence electric capacity (negative phase-sequence electric capacity equals positive sequence electric capacity) parameter measurement error and the transmission line length relation that adopt the inventive method and classic method measurement to obtain respectively.

The line capacitance measuring error that table 1 utilizes the inventive method to measure and line length relation

As can be seen from Table 1, the measuring error of two kinds of methods all can increase along with the increase of line length, but the circuit of more than 200km all can adopt three-phase transposition to make three-phase symmetrical, disturb less, therefore the measurement of 200km Above Transmission Lines is not considered.

Classic method measures the capacitance parameter of this circuit, when line length changes from 15km to 200km, zero sequence capacitance measurement error is increased to 29.969% from 12.186%, positive sequence capacitance measurement error is then increased to 27.163% by 12.891%, and therefore traditional measurement method cannot meet the requirement of measuring accuracy.

The capacitance parameter of this circuit is measured by the inventive method, when line length changes from 15km to 200km, zero sequence capacitance measurement error is increased to 1.6818% from 0.1045%, and positive sequence capacitance measurement error is then increased to 1.7284% by 0.1341%, can meet engineering survey requirement.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendment or supplement or adopt similar mode to substitute to described specific embodiment, but can't depart from spirit of the present invention or surmount the scope that appended claims defines.

Claims (3)

1., based on a not transposed transmission line Xc interference detecting method for harmonic component, define transmission line of electricity a to be measured, normally run and bring the transmission line of electricity b of Hz noise, measuring process comprises:

Step 1, by step-up transformer, apply three-phase main-frequency voltage at measured circuit a head end, circuit a terminal open circuit, end current is 0; Utilize the three-phase voltage based on the synchronous measuring apparatus synchronous acquisition circuit a head end of GPS technology the three-phase voltage of end with the three-phase current of head end

Step 2, exchanges the wiring position of A phase and B phase and circuit in head end three-phase supply, utilizes the three-phase voltage of the synchronous measuring apparatus synchronous acquisition circuit a head end based on GPS technology the three-phase voltage of end with the three-phase current of head end ${\stackrel{.}{I}}_{\mathrm{aS}}^2,{\stackrel{.}{I}}_{\mathrm{bS}}^2,{\stackrel{.}{I}}_{\mathrm{cS}}^2;$

Step 3, exchanges the wiring position of A phase and C phase and circuit in head end three-phase supply, utilizes the three-phase voltage of the synchronous measuring apparatus synchronous acquisition circuit a head end based on GPS technology the three-phase voltage of end with the three-phase current of head end ${\stackrel{.}{I}}_{\mathrm{aS}}^3,{\stackrel{.}{I}}_{\mathrm{bS}}^3,{\stackrel{.}{I}}_{\mathrm{cS}}^3;$

Step 4, to three-phase voltage and the three-phase current data of the three groups of head and ends obtained under step 1, step 2 and step 3 three kinds of independent metering systems, adopt the FFT interpolation algorithm process adding Hanning window, obtain the three-phase voltage of three groups of head and ends and the third-harmonic component of three-phase current, comprising:

Under first time measurement, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Under second time is measured, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Under third time measurement, the third-harmonic component of circuit a head end three-phase voltage the third-harmonic component of end three-phase voltage with the third-harmonic component of head end three-phase current

Step 5, by third harmonic voltage and the triple harmonic current of three groups of circuit head and ends, and circuit model:

$\left[\begin{array}{ccc}{\stackrel{\·}{I}}_{aS3}^1& {\stackrel{\·}{I}}_{aS3}^2& {\stackrel{\·}{I}}_{aS3}^3\\ {\stackrel{\·}{I}}_{bS3}^1& {\stackrel{\·}{I}}_{bS3}^2& {\stackrel{\·}{I}}_{bS3}^3\\ {\stackrel{\·}{I}}_{cS3}^1& {\stackrel{\·}{I}}_{cS3}^2& {\stackrel{\·}{I}}_{cS3}^3\end{array}\right]=\frac{1}{2}{Y}_3\left[\begin{array}{ccc}{\stackrel{\·}{U}}_{aS3}^1+{\stackrel{\·}{U}}_{aM3}^1& {\stackrel{\·}{U}}_{aS3}^2+{\stackrel{\·}{U}}_{aM3}^2& {\stackrel{\·}{U}}_{aS3}^3+{\stackrel{\·}{U}}_{aM3}^3\\ {\stackrel{\·}{U}}_{bS3}^1+{\stackrel{\·}{U}}_{bM3}^1& {\stackrel{\·}{U}}_{bS3}^2+{\stackrel{\·}{U}}_{bM3}^2& {\stackrel{\·}{U}}_{bS3}^3+{\stackrel{\·}{U}}_{bM3}^3\\ {\stackrel{\·}{U}}_{cS3}^1+{\stackrel{\·}{U}}_{cM3}^1& {\stackrel{\·}{U}}_{cS3}^2+{\stackrel{\·}{U}}_{cM3}^2& {\stackrel{\·}{U}}_{cS3}^3+{\stackrel{\·}{U}}_{cM3}^3\end{array}\right]$

Wherein, Y ₃admittance matrix under circuit third harmonic frequencies:

$Y_3=\left[\begin{array}{ccc}{Y}_{a3}& Y_{ab3}& Y_{ac3}\\ Y_{ab3}& Y_{b3}& Y_{bc3}\\ Y_{ac3}& Y_{bc3}& Y_{c3}\end{array}\right]$

Y _a3for the admittance under measured circuit A phase third harmonic frequencies, Y _b3for the admittance under measured circuit B phase third harmonic frequencies, Y _c3for the admittance under measured circuit C phase third harmonic frequencies, Y _ab3, Y _ac3, Y _bc3for the transadmittance under third harmonic frequencies between the different two-phase of measured circuit;

Solve an equation and try to achieve admittance matrix Y ₃;

Step 6, is converted to the sequence capacitance matrix under fundamental frequency by the phase admittance matrix under measured circuit third harmonic frequencies, simultaneously divided by line length l, obtain the capacitance parameter of every km; Comprise zero sequence electric capacity C ₀, positive sequence electric capacity C ₁, negative phase-sequence electric capacity C ₂, and different two sequences between mutual capacitance C ₀₁, C ₀₂, C ₁₀, C ₁₂, C ₂₀, C ₂₁;

In above formula, l is line length, and w=2 π f, f are mains frequency.

2. the not transposed transmission line Xc interference detecting method based on harmonic component according to claim 1, be characterised in that: in described step 1,2,3,4, by the third harmonic that saturation transformer produces in measuring circuit, utilize the three-phase voltage based on the synchronous measuring apparatus measuring circuit head and end of GPS technology and three-phase current, adopt the FFT interpolation algorithm adding Hanning window to the voltage and current process of circuit head and end, obtain the three-phase voltage of head and end and the third-harmonic component of three-phase current, utilize harmonic component to calculate.

3. the not transposed transmission line Xc interference detecting method based on harmonic component according to claim 1, be characterised in that: in described step 5 and step 6, consider that the mutual parameter between circuit two-phase that do not replace is unequal, utilize harmonic component to solve the self-admittance of all phases and alternate transadmittance, so obtain orderly capacitance parameter.