CN101419254A - Uhv transmission line parameter measuring systems and method - Google Patents

Abstract

The invention concretely discloses a system and a method for measuring parameters of ultra-high voltage transmission lines. The system comprises an adjustable voltage power supply, a voltage transformer, a first current transformer, a first measuring device, a second current sensor, a second measuring device, and a data processing unit; and the system also comprises a compensation capacitor connected between a first end three-phase of the measured ultra-high voltage transmission lines and the ground, wherein the compensation capacitor is used to reduce the current of the test change primary side. The invention also discloses a method for measuring parameters of the ultra-high voltage transmission lines. The system and the method can simply and conveniently realize the measurement of power frequency parameters of the ultra-high voltage transmission lines.

Description

A kind of Uhv transmission line parameter measuring systems and method

Technical field

The present invention relates to the high voltage power transmission field, particularly relate to a kind of Uhv transmission line parameter measuring systems and method.

Background technology

Before ultra-high-tension power transmission line puts into operation,, need measure the circuit power frequency parameter of ultra-high-tension power transmission line for the trend of calculating whole network system distributes, sets the corresponding protection definite value for circuit.

The circuit power frequency parameter of ultra-high-tension power transmission line mainly comprises: mutual inductive impedance between the direct current resistance of transmission line of electricity, positive sequence impedance, zero sequence impedance, positive sequence electric capacity and zero sequence electric capacity and double-circuit line and coupling capacitance etc.

See figures.1.and.2, be respectively described ultra-high-tension power transmission line parameter measurement system test positive sequence impedance of prior art and zero sequence impedance circuit diagram.

Described system comprises: but voltage controller power source 1, voltage transformer (VT) 2, first current transformer 3, first measurement mechanism 4, second current transformer 5, second measurement mechanism 6 and data processing unit 7.

Referring to Fig. 1, when measuring positive sequence impedance, the tested transmission line of electricity head end three adjustable voltage source 1 of joining, terminal three-phase short circuit.First measurement mechanism 4 is connected with tested transmission line of electricity head end three with first current transformer 3 by voltage transformer (VT) 2 respectively.Second measurement mechanism 6 is connected with tested transmission line of electricity end three by second current transformer 5.Data processing unit 7 links to each other with second measurement mechanism 6 with first measurement mechanism 4 respectively, receives the experimental data that measures, and calculates the positive sequence impedance of tested transmission line of electricity.

Referring to Fig. 2, when measuring zero sequence impedance, tested transmission line of electricity head end three-phase short circuit, terminal three-phase short circuit and ground connection.But voltage controller power source 1 adaper end three-phase shorting stub is for tested transmission line of electricity head end wheel applies the single phase industrial frequence alternating voltage mutually.It is single-phase that first measurement mechanism 4 passes through voltage transformer (VT) 2 and the 3 difference adaper end three-phase shorting stubs of first current transformer and head end.Second measurement mechanism 6 connects terminal three-phase shorting stub by second current transformer 5.Data processing unit 7 links to each other with second measurement mechanism 6 with first measurement mechanism 4 respectively, receives the experimental data that measures, and calculates the positive sequence impedance of tested transmission line of electricity.

In order to improve power transmission efficiency, reduce line loss, reduce cost of investment, to economize the land resource, implementing the UHV transmission line engineering is the inexorable trend of China's power network development.

Compare with common transmission line of electricity, UHV transmission line has that circuit is long, voltage is high and characteristics such as parameter value is bigger.Generally, the line parameter circuit value of UHV transmission line is 5～20 times of common line.Simultaneously, because UHV transmission line is long, its parallel cross link is many again, and therefore, the electromagnetic interference (EMI) between parallel circuit is bigger.When measuring power frequency parameter, the undesired signal that the circuit peripheral electromagnetic field causes is superimposed upon on the measuring-signal, has a strong impact on the accuracy of parameter measurement.

When adopting the described measuring system of prior art to carry out the parameter measurement of UHV transmission line, need increase test voltage or measuring current to carry out anti-interference.By improving the amplitude of test signal, reduce the ratio of undesired signal in resultant signal accordingly, promptly adopt the method that improves signal to noise ratio (S/N ratio) to improve measuring accuracy.

With 1000kV Changzhi-Nanyang UHV transmission line engineering is that example describes.Referring to table 1, be prior art 1000kV Changzhi-Nanyang line parameter circuit value experiment with measuring device parameter list.

Table 1

Adopt the described system of prior art, when selecting testing equipment, obtain pressure regulator and test the capacity that becomes by Theoretical Calculation according to positive sequence impedance and zero sequence impedance respectively.

When selecting place capacity, suppose to test line to apply the 30A electric current that three compatible amount of equipment needed thereby (pressure regulator, testing transformer) should be 143.7～153.6kVA according to the positive sequence impedance calculated value.When selecting place capacity, suppose to test line to apply the 30A electric current that the single-phase capacity of equipment needed thereby (pressure regulator, testing transformer) should be 75.7～115.5kVA according to the zero sequence impedance calculated value.If consider the versatility and the nargin of testing equipment, single transformer and testing transformer that should respectively to select three capacity be 120kVA.

Obviously, when the described system of prior art carried out parameter measurement to UHV transmission line, when tested transmission line of electricity applied big current signal, because the current value ratio of test change primary side is bigger, the power of its required testing equipment was all bigger.And powerful testing equipment often volume is bigger, comparatively heavy, the testing equipment transition is inconvenient, measuring process more complicated, difficulty.

Summary of the invention

Technical matters to be solved by this invention provides a kind of Uhv transmission line parameter measuring systems and method, and realization that can be easy is to the power frequency parameter measuring of UHV transmission line.

The invention provides a kind of Uhv transmission line parameter measuring systems, but described system comprises voltage controller power source, voltage transformer (VT), first current transformer, first measurement mechanism, second current sensor, second measurement mechanism and data processing unit; It is characterized in that described system also comprises: be connected on the building-out capacitor between tested UHV transmission line head end three phase and ground; Described building-out capacitor is used to reduce the electric current that test becomes primary side.

Preferably, when measuring the positive sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_x=\frac{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2}-{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">C</figure-callout>}}_1/2$

Wherein, C _XBe building-out capacitor; C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity, Z ₁Be discreet value of tested transmission line of electricity positive sequence impedance and z ₁=R ₁+ jX ₁

Preferably, when measuring the zero sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{{3X}_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{3C_0}{2}$

Wherein, C _XBe building-out capacitor; C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and Z ₀=R ₀+ jX ₀

Preferably, described system also comprises first oscillograph and second oscillograph;

Described first oscillograph is used for writing down respectively described voltage transformer (VT) and described first current transformer and detects the tested transmission line of electricity three-phase head end line voltage that obtains and the waveform of head end phase current, is sent to described data processing unit;

Described second oscillograph is used to write down the waveform that described second current transformer detects the terminal phase current of tested transmission line of electricity three-phase that obtains, and is sent to described data processing unit.

Preferably, described system also comprises a GPS synchronous clock, the 2nd GPS synchronous clock and sync waveform interception unit;

A described GPS synchronous clock and described the 2nd GPS synchronous clock are used at default fixed time, exporting synchronizing clock signals simultaneously to described first oscillograph and described second oscillograph, is the wave label GPS synchronous time mark of first oscillograph and second oscillograph record;

Described sync waveform interception unit intercepts according to the waveform of described GPS synchronous time mark to first oscillograph and second oscillograph record, and the waveform that is truncated to is sent to data processing unit.

Preferably, the sample frequency of a described GPS synchronous clock and the 2nd GPS synchronous clock is 200ks/S.

The present invention also provides a kind of Uhv transmission line parameter measuring method, and described method comprises:

Select to measure positive sequence impedance or zero sequence impedance, measure wiring;

Tested transmission line of electricity head end three-phase is passed through building-out capacitor ground connection respectively;

Measure tested transmission line of electricity head end phase voltage, head end phase current and terminal phase current;

Described head end phase voltage, head end phase current and terminal phase current according to measuring calculate tested transmission line of electricity positive sequence impedance and zero sequence impedance.

Preferably, when measuring the positive sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2}-\frac{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}{2}$

Wherein, C _XBe building-out capacitor; C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity; Z ₁Be discreet value of tested transmission line of electricity positive sequence impedance and Z ₁=R ₁+ jX ₁

Preferably, when measuring the zero sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{{3X}_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{3C_0}{2}$

Wherein, C _XBe building-out capacitor; C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and Z ₀=R ₀+ jX ₀

Preferably, before calculating tested transmission line of electricity positive sequence impedance and zero sequence impedance, further comprise:

The waveform of record head end phase voltage, head end phase current and terminal phase current.

Preferably, further comprise during the waveform of record head end phase voltage, head end phase current and terminal phase current:

Wave label GPS synchronous time mark to head end phase voltage, head end phase current and terminal phase current;

Waveform according to described synchronous time mark intercepting head end phase voltage, head end phase current and terminal phase current.

Compared with prior art, the present invention has the following advantages:

Uhv transmission line parameter measuring systems of the present invention and method, by on the basis of the described measuring system of prior art, between tested UHV transmission line head end three phase and ground, connect building-out capacitor, reduce the electric current that test becomes primary side, when making tested UHV transmission line apply big current signal, the electric current that test becomes primary side is no more than load current value.Like this, when the positive sequence impedance of measuring UHV transmission line and zero sequence impedance, only need to adopt conventional low capacity testing equipment just can satisfy testing requirements, make the parameter measurement of UHV transmission line become simple, convenient.

Description of drawings

Fig. 1 is the described ultra-high-tension power transmission line parameter measurement system test of a prior art positive sequence impedance circuit diagram;

Fig. 2 is the described ultra-high-tension power transmission line parameter measurement system test of a prior art zero sequence impedance circuit diagram;

Fig. 3 is the described Uhv transmission line parameter measuring systems test of a first embodiment of the invention positive sequence impedance circuit diagram;

Fig. 4 is the described Uhv transmission line parameter measuring systems test of a first embodiment of the invention zero sequence impedance circuit diagram;

Fig. 5 is a positive sequence impedance building-out capacitor computation model synoptic diagram;

Fig. 6 is a zero sequence impedance building-out capacitor computation model synoptic diagram;

Fig. 7 is the described Uhv transmission line parameter measuring systems test of a second embodiment of the invention positive sequence impedance circuit diagram;

Fig. 8 is the described Uhv transmission line parameter measuring systems test of a second embodiment of the invention zero sequence impedance circuit diagram;

Fig. 9 is a Uhv transmission line parameter measuring method flow diagram of the present invention.

Embodiment

For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

With reference to Fig. 3 and Fig. 4, be respectively described Uhv transmission line parameter measuring systems test positive sequence impedance of first embodiment of the invention and zero sequence impedance circuit diagram.

Described Uhv transmission line parameter measuring systems comprises: but voltage controller power source 11, voltage transformer (VT) 12, first current transformer 13, first measurement mechanism 14, second current transformer 15, second measurement mechanism 16, data processing unit 17 and building-out capacitor C _X18.

With reference to Fig. 3 and Fig. 4, building-out capacitor C _X18.Be connected on respectively between tested UHV transmission line head end three phase and ground, be used for reducing test and become primary side current.

Connect building-out capacitor C respectively by head end three-phase at tested UHV transmission line _X18, in the time of can guaranteeing to carry out the measurement of positive sequence impedance and zero sequence impedance, tested UHV transmission line applies big current signal, the electric current that test becomes primary side is no more than load current value, and can reduce each test instrumentation output current in the measurement mechanism as much as possible, to guarantee the safety and the antijamming capability of each test instrumentation in the test process.

When measuring, need to select suitable building-out capacitor value for the different power frequency parameters of UHV transmission line.

(1) measures positive sequence impedance

With reference to Fig. 3, when measuring positive sequence impedance, building-out capacitor C _XBe connected on respectively between tested transmission line of electricity head end three phase and ground.

With reference to Fig. 5, be positive sequence impedance building-out capacitor computation model synoptic diagram.

UHV transmission line adopts heavy in section multiple fission conductor (as 8 * LGJ-500/35 steel-cored aluminium strand), and transmission line of electricity is long, when calculating the positive sequence impedance capacitance compensation, can not ignore the influence of positive sequence electric capacity.

Among Fig. 5, connect positive sequence building-out capacitor C at tested transmission line of electricity head end _x, C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity, Z ₁Be the discreet value of tested transmission line of electricity positive sequence impedance.

Wherein, Z ₁=R ₁+ jX ₁

Existing test becomes the primary side current ratings and is 10A, and it is 30A that tested transmission line of electricity applies electric current.When measuring positive sequence impedance, the present invention increases building-out capacitor C _XPurpose be: when tested transmission line of electricity applied the 30A electric current, warranty test became primary side current and is no more than ratings, and reduces the output current of testing equipment as far as possible.

Order: C=C _x+ C ₁/ 2, According to the three-phase equilibrium symmetry as can be known, head end S point and terminal M point current potential equate that then test change primary side current can be tried to achieve by formula (1):

Test become the primary side current value into:

$I_1=\sqrt{{(I_2-\mathrm{\&omega;}{\mathrm{CI}}_2{X}_1)}^2+{\left(\mathrm{\&omega;}{\mathrm{CR}}_1{I}_2\right)}^2}=I_2\sqrt{{(1-\mathrm{\&omega;}{\mathrm{CX}}_1)}^2+{\left(\mathrm{\&omega;}{\mathrm{CR}}_1\right)}^2}---\left(2\right)$

Wherein, C=C _x+ C ₁/ 2, Z ₁=R ₁+ jX ₁

The positive sequence impedance discreet value Z of tested transmission line of electricity ₁Remain unchanged, i.e. R ₁And X ₁Remain unchanged, ω remains unchanged.Therefore, in order to make test become primary side current value I ₁Minimum can make:

dI ₁/dC＝0 (3)

Find the solution formula (3) and obtain making I ₁The condition that satisfies of hour C:

$C=\frac{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2}---\left(4\right)$

And then try to achieve positive sequence building-out capacitor C when measuring _xValue be:

$C_X=\frac{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2}-\frac{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}{2}---\left(5\right)$

Wherein, C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity, Z ₁Be discreet value of tested transmission line of electricity positive sequence impedance and Z ₁=R ₁+ jX ₁

When measuring the positive sequence impedance of UHV transmission line, according to positive sequence impedance of pre-estimating and positive sequence electric capacity, calculate the value of building-out capacitor, select corresponding capacitor, be connected on respectively between tested transmission line of electricity head end three phase and ground, can make test become primary side current and reach minimum, make it be lower than ratings, the testing equipment that guarantees low capacity can normally be measured, thereby makes measuring process easier.

The detailed process of measuring positive sequence impedance may further comprise the steps:

Steps A 1:, obtain tested transmission line of electricity positive sequence impedance discreet value Z by pre-estimating according to long-term test experience ₁With positive sequence electric capacity discreet value C ₁

Step B1: according to positive sequence impedance discreet value Z ₁With positive sequence electric capacity discreet value C ₁, calculate positive sequence building-out capacitor value C _X

$C_X=\frac{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2}-\frac{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}{2}---\left(5\right)$

Wherein, C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity, Z1 is discreet value of tested transmission line of electricity positive sequence impedance and Z ₁=R ₁+ jX ₁

Step C1: according to the positive sequence building-out capacitor C that calculates _X, select suitable capacitor, be connected on respectively between head end three phase and ground of tested transmission line of electricity.

Step D1: carry out the positive sequence impedance experiment with measuring.

By between head end three phase and ground of tested transmission line of electricity, connecting positive sequence building-out capacitor C respectively _XMake when carrying out the positive sequence impedance measurement,, also can be no more than ratings by warranty test change primary side current even tested transmission line of electricity applies big current signal, and reduce the output current of testing equipment as far as possible, to guarantee the safety and the antijamming capability of testing equipment in the test process.

Preferably, among the step C1, according to calculating positive sequence building-out capacitor C _X, when selecting suitable capacitor, can adopt following method:

When carrying out the positive sequence impedance measurement with 1000kV Changzhi-Nanyang, Nanyang-Jingmen section UHV transmission line, building-out capacitor C _XThe example that is chosen as describe.

Referring to table 2, when carrying out the positive sequence impedance measurement for 1000kV Changzhi-Nanyang, Nanyang-Jingmen section UHV transmission line, building-out capacitor value and test become primary side current Value Data table.Wherein, applying electric current on the described UHV transmission line is 30A.

Table 2

At first, can see, by between tested transmission line of electricity head end three phase and ground, connecting building-out capacitor C respectively by table 2 _X, when tested transmission line of electricity applied the 30A electric current, test became primary side current and reduces greatly, and average current is far smaller than 10A about 0.86A, realized goal of the invention of the present invention.

Referring to table 2, when calculating the positive sequence impedance of test 1000kV Nanyang-Jingmen section extra high voltage line, its positive sequence building-out capacitor C _XThe value ideal value should be between 39.204 μ F～42.098 μ F.According to actual conditions, can select positive sequence building-out capacitor C _XBe 43 μ F.At this moment, still can satisfy test and become the requirement that primary side current is lower than rated current.

Further,, can select the electric capacity combination in parallel of 3 10 μ F and 1 13 μ F, constitute the positive sequence building-out capacitor C of 43 μ F for the capacity that reduces single electric capacity and the versatility of equipment _XBe connected between 1000kV Nanyang-Jingmen section extra high voltage line head end three phase and ground.

(2) measure zero sequence impedance

With reference to Fig. 4, when measuring zero sequence impedance, building-out capacitor C _XBe connected between tested transmission line of electricity head end three-phase shorting stub and the ground.

With reference to Fig. 6, be zero sequence impedance building-out capacitor computation model synoptic diagram.

Equally, when calculating the zero sequence impedance compensation, can not ignore the influence of zero sequence electric capacity.

Among Fig. 6, connect the zero sequence compensation capacitor C at tested transmission line of electricity head end _A, C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Zero sequence impedance discreet value for tested transmission line of electricity.

Wherein, Z ₀=R ₀+ jX ₀

Existing test becomes the primary side current ratings and is 10A, and it is 30A that tested transmission line of electricity applies electric current.When measuring zero sequence impedance, the present invention increases building-out capacitor C _XPurpose be: when tested transmission line of electricity applied the 30A electric current, warranty test became primary side current and is no more than ratings, and reduces the output current of testing equipment as far as possible.

Order: C=C _x+ 3C ₀/ 2, Then test change primary side current can be tried to achieve by formula (6):

Test become the primary side current value into:

$I_1=\sqrt{{(I_2-\frac{1}{3}\mathrm{\&omega;}{\mathrm{CI}}_2{X}_0)}^2+{\left(\frac{1}{3}\mathrm{\&omega;}{\mathrm{CR}}_0{I}_2\right)}^2}=I_2\sqrt{{(1-\frac{1}{3}\mathrm{\&omega;}{\mathrm{CX}}_0)}^2+{\left(\frac{1}{3}\mathrm{\&omega;}{\mathrm{CR}}_0\right)}^2}---\left(7\right)$

Wherein, C=C _x+ 3C ₀/ 2, Z ₀=R ₀+ jX ₀

The zero sequence impedance discreet value Z of tested transmission line of electricity ₀Remain unchanged, i.e. R ₀And X ₀Remain unchanged, ω remains unchanged.Therefore, in order to make test become primary side current value I ₁Minimum can make:

dI ₂/dC＝0 (8)

Find the solution formula (8) and obtain making I ₁The condition that satisfies of hour C:

$C=\frac{3X_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}---\left(9\right)$

And then try to achieve zero sequence building-out capacitor C when measuring _xValue be:

$C_X=\frac{{3X}_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{{3C}_0}{2}---\left(10\right)$

Wherein, C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and z ₀=R ₀+ jX ₀

When measuring the zero sequence impedance of UHV transmission line, according to zero sequence impedance of pre-estimating and zero sequence electric capacity, calculate the value of building-out capacitor, select corresponding capacitor, be connected between tested transmission line of electricity head end three-phase shorting stub and the ground, can make test become primary side current and reach minimum, make it be lower than ratings, the testing equipment that guarantees low capacity can normally be measured, thereby makes measuring process easier.

The detailed process of measuring zero sequence impedance may further comprise the steps:

Steps A 2:, obtain tested transmission line of electricity zero sequence impedance discreet value z by estimating according to long-term test experience ₀With zero sequence electric capacity discreet value C ₀

Step B2: according to zero sequence impedance discreet value Z ₀With zero sequence electric capacity discreet value C ₀, calculate zero sequence compensation capacitance C _X

$C_X=\frac{{3X}_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{{3C}_0}{2}---\left(10\right)$

Wherein, C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and Z ₀=R ₀+ jX ₀

Step C2: according to the positive sequence building-out capacitor C that calculates _X, select suitable capacitor, be connected on respectively between the shorting stub of head end three-phase and ground of tested transmission line of electricity.

Step D2: carry out the zero sequence impedance experiment with measuring.

By being connected the zero sequence compensation capacitor C between the head end three-phase shorting stub of tested transmission line of electricity and the ground _XMake when carrying out the zero sequence impedance measurement,, also can be no more than ratings by warranty test change primary side current even test line applies big current signal, and reduce the output current of testing equipment as far as possible, to guarantee the safety and the antijamming capability of testing equipment in the test process.

Preferably, among the step C2, according to the zero sequence compensation capacitor C that calculates _X, when selecting suitable capacitor, can adopt following method:

When carrying out the zero sequence impedance measurement with 1000kV Changzhi-Nanyang, Nanyang-Jingmen section UHV transmission line, the example that is chosen as of building-out capacitor describes.

Referring to table 3, when carrying out the zero sequence impedance measurement for 1000kV Changzhi-Nanyang, Nanyang-Jingmen section UHV transmission line, building-out capacitor value and test become primary side test current Value Data table.Wherein, applying electric current on the described UHV transmission line is 30A.

Table 3

At first, can see, by being connected building-out capacitor C between the shorting stub of tested transmission line of electricity head end three-phase and the ground by table 3 _X, when tested transmission line of electricity applied the 30A electric current, test became primary side current and reduces greatly, and average current is far smaller than 10A about 5～6A, realized goal of the invention of the present invention.

Referring to table 3, when calculating the zero sequence impedance of test 1000kV Changzhi-Nanyang section extra high voltage line, its zero sequence compensation capacitor C _XThe value ideal value should be between 19.345 μ F～32.394 μ F.According to actual conditions, can select the zero sequence compensation capacitor C _XBe 33 μ F.At this moment, still can satisfy test and become the requirement that a side electric current is lower than the test rated current.

Further,, can select the electric capacity combination in parallel of 2 10 μ F and 1 13 μ F, constitute the zero sequence compensation capacitor C of 33 μ F for the capacity that reduces single electric capacity and the versatility of equipment _XBe connected between 1000kV Changzhi-Nanyang each phase and ground of section extra high voltage line head end.

Uhv transmission line parameter measuring systems of the present invention, by on the basis of the described measuring system of prior art, between tested UHV transmission line head end three phase and ground, connect building-out capacitor, reduce the electric current that test becomes primary side, when making tested UHV transmission line apply big current signal, the electric current that test becomes primary side is no more than load current value.Like this, when the positive sequence impedance of measuring UHV transmission line and zero sequence impedance, only need to adopt conventional low capacity testing equipment just can satisfy testing requirements, make the parameter measurement of UHV transmission line become simple, convenient.

Further, in order to strengthen the accuracy of Uhv transmission line parameter measuring, can adopt oscillograph respectively at the head of tested transmission line of electricity, last two ends, the waveform of record head, terminal voltage, current signal, enrich the data volume of calculation of parameter, improve the accuracy of parameter measurement.

With reference to Fig. 7 and Fig. 8, be respectively described Uhv transmission line parameter measuring systems test positive sequence impedance of second embodiment of the invention and zero sequence impedance circuit diagram.

The difference of embodiment two described systems and embodiment one is that described system further comprises: first oscillograph 19 and second oscillograph 20.

First oscillograph 19 is arranged on tested transmission line of electricity head end, be connected on respectively between voltage transformer (VT) 12 and first current transformer 13 and the data processing unit 17, be used for the recording voltage mutual inductor 12 respectively and first current transformer 13 and detect the tested transmission line of electricity three-phase head end line voltage that obtains and the waveform of head end phase current, store and be sent to data processing unit 17.

Second oscillograph 20 is arranged on tested transmission line of electricity end, be connected between second current transformer 15 and the data processing unit 17, be used to write down the waveform that second current transformer 15 detects the terminal phase current of tested transmission line of electricity three-phase that obtains, store and be sent to data processing unit 17.

Preferably, in order to strengthen the precision of tested power transmission line power frequency parameters measuring, make voltage, the phase angle difference between the current signal of tested transmission line of electricity head, end as much as possible little, described system further comprises: a GPS synchronous clock 21, the 2nd GPS synchronous clock 22, and sync waveform interception unit 23.

The one GPS synchronous clock 21 is arranged on tested transmission line of electricity head end, links to each other with first oscillograph 19.The 2nd GPS synchronous clock 22 is arranged on tested transmission line of electricity end, links to each other with second oscillograph 20.Sync waveform interception unit 23 is connected on respectively between first oscillograph 19 and second oscillograph 20 and the data processing unit 17.

When carrying out power frequency parameter measuring, at default a certain fixed time, the one GPS synchronous clock 21 and the 2nd GPS synchronous clock 22 are exported synchronizing clock signals to the first oscillograph 19 and second oscillograph 20 simultaneously, make head, terminal voltage, the current waveform of first oscillograph 19 and second oscillograph, 20 records have the GPS synchronous time mark simultaneously.

Sync waveform interception unit 23 intercepts according to head, terminal voltage, the current waveform of described GPS synchronous time mark to first oscillograph 19 and second oscillograph, 20 records, and the waveform that is truncated to is sent to data processing unit 17.

By adopting said system, tested transmission line of electricity head, terminal voltage, current waveform are recorded ripple synchronously, make the phasing degree of the head end phase voltage, head end phase current and the terminal phase current that measure identical, realize the wide area both-end synchro measure of UHV transmission line.

Preferably, the sample frequency of a GPS synchronous clock 21 and the 2nd GPS synchronous clock 22 is 200ks/S, and the phasing degree difference that can make tested transmission line of electricity head, terminal phase voltage and phase current is about 0.02 degree.

Adopt the embodiment of the invention two described parameter measurement systems, when realizing, can also further improve the accuracy of power frequency parameter measuring the easy measurement of UHV transmission line power frequency parameter.

The present invention also provides a kind of Uhv transmission line parameter measuring method, is used for the power frequency parameter of UHV transmission line is measured.

With reference to Fig. 9, be Uhv transmission line parameter measuring method flow diagram of the present invention.Said method comprising the steps of:

Step S901: select to measure positive sequence impedance or zero sequence impedance, measure wiring accordingly.

When selecting to measure positive sequence impedance, the terminal three-phase shortcircuit of tested transmission line of electricity, head end applies three-phase positive sequence power-frequency voltage.When selecting to measure zero sequence impedance, terminal three-phase shortcircuit of tested transmission line of electricity and ground connection, head end three-phase short circuit, wheel apply single phase industrial frequence voltage mutually.

Step S902: tested transmission line of electricity head end three-phase is passed through building-out capacitor ground connection respectively.

(1) when selecting to measure positive sequence impedance, adopt following step to determine the building-out capacitor value:

Steps A 1:, obtain tested transmission line of electricity positive sequence impedance discreet value Z by pre-estimating according to long-term test experience ₁With positive sequence electric capacity discreet value C ₁

Step B1: according to positive sequence impedance discreet value Z ₁With positive sequence electric capacity discreet value C ₁, calculate positive sequence building-out capacitor value C _X

$C_X=\frac{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2}-\frac{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="A200810183471E00181.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}{2}---\left(5\right)$

Wherein, C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity, Z1 is discreet value of tested transmission line of electricity positive sequence impedance and Z ₁=R ₁+ jX ₁

Step C1: according to the positive sequence building-out capacitor C that calculates _X, select suitable capacitor, be connected on respectively between head end three phase and ground of tested transmission line of electricity.

(2) when selecting to measure zero sequence impedance, adopt following step to determine the building-out capacitor value:

Steps A 2:, obtain tested transmission line of electricity zero sequence impedance discreet value Z by estimating according to long-term test experience ₀With zero sequence electric capacity discreet value C ₀

Step B2: according to zero sequence impedance discreet value Z ₀With zero sequence electric capacity discreet value C ₀, calculate zero sequence compensation capacitance C _X

$C_X=\frac{{3X}_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{{3C}_0}{2}---\left(10\right)$

Wherein, C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and Z ₀=R ₀+ jX ₀

Step C2: according to the positive sequence building-out capacitor C that calculates _X, select suitable capacitor, be connected on respectively between the shorting stub of head end three-phase and ground of tested transmission line of electricity.

Step S903: measure head end phase voltage, head end phase current and terminal phase current.

Step S904:, calculate tested transmission line of electricity positive sequence impedance and zero sequence impedance according to the head end phase voltage that measures, head end phase current and terminal phase current.

Uhv transmission line parameter measuring method of the present invention, by on the basis of the described measuring system of prior art, between tested UHV transmission line head end three phase and ground, connect building-out capacitor, reduce the electric current that test becomes primary side, when making tested UHV transmission line apply big current signal, the electric current that test becomes primary side is no more than load current value.Like this, when the positive sequence impedance of measuring UHV transmission line and zero sequence impedance, only need to adopt conventional low capacity testing equipment just can satisfy testing requirements, make the parameter measurement of UHV transmission line become simple, convenient.

Preferably, before entering step 904, described method further comprises: at tested transmission line of electricity first and last end oscillograph is set respectively, the waveform of record head end phase voltage, head end phase current and terminal phase current.

Preferably, when the waveform of record head end phase voltage, head end phase current and terminal phase current, adopt the GPS synchronous clock respectively, simultaneously to the wave label GPS synchronous time mark of head end phase voltage, head end phase current and terminal phase current; Waveform according to described synchronous time mark intercepting head end phase voltage, head end phase current and terminal phase current.

Adopt said method, tested transmission line of electricity head, terminal voltage, current waveform are recorded ripple synchronously, make the phasing degree of the head end phase voltage, head end phase current and the terminal phase current that measure identical, realize the wide area both-end synchro measure of UHV transmission line.When realizing, can also further improve the accuracy of power frequency parameter measuring to the easy measurement of UHV transmission line power frequency parameter.

More than to a kind of Uhv transmission line parameter measuring systems provided by the present invention and method, be described in detail, used specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (11)

1, a kind of Uhv transmission line parameter measuring systems, but described system comprises voltage controller power source, voltage transformer (VT), first current transformer, first measurement mechanism, second current sensor, second measurement mechanism and data processing unit; It is characterized in that described system also comprises: be connected on the building-out capacitor between tested UHV transmission line head end three phase and ground; Described building-out capacitor is used to reduce the electric current that test becomes primary side.

2, system according to claim 1 is characterized in that, when measuring the positive sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{X_1}{\mathrm{\&omega;}{X}_1^2+\mathrm{\&omega;}{R}_1^2}-C_1/2$

Wherein, C _XBe building-out capacitor; C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity, Z ₁Be discreet value of tested transmission line of electricity positive sequence impedance and Z ₁=R ₁+ jX ₁

3, system according to claim 1 is characterized in that, when measuring the zero sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{3X_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{3C_0}{2}$

Wherein, C _XBe building-out capacitor; C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and Z ₀=R ₀+ jX ₀

4, system according to claim 1 is characterized in that, described system also comprises first oscillograph and second oscillograph;

Described first oscillograph is used for writing down respectively described voltage transformer (VT) and described first current transformer and detects the tested transmission line of electricity three-phase head end line voltage that obtains and the waveform of head end phase current, is sent to described data processing unit;

Described second oscillograph is used to write down the waveform that described second current transformer detects the terminal phase current of tested transmission line of electricity three-phase that obtains, and is sent to described data processing unit.

5, system according to claim 4 is characterized in that, described system also comprises a GPS synchronous clock, the 2nd GPS synchronous clock and sync waveform interception unit;

A described GPS synchronous clock and described the 2nd GPS synchronous clock are used at default fixed time, exporting synchronizing clock signals simultaneously to described first oscillograph and described second oscillograph, is the wave label GPS synchronous time mark of first oscillograph and second oscillograph record;

Described sync waveform interception unit intercepts according to the waveform of described GPS synchronous time mark to first oscillograph and second oscillograph record, and the waveform that is truncated to is sent to data processing unit.

6, system according to claim 5 is characterized in that, the sample frequency of a described GPS synchronous clock and the 2nd GPS synchronous clock is 200ks/S.

7, a kind of Uhv transmission line parameter measuring method is characterized in that, described method comprises:

Select to measure positive sequence impedance or zero sequence impedance, measure wiring;

Tested transmission line of electricity head end three-phase is passed through building-out capacitor ground connection respectively;

Measure tested transmission line of electricity head end phase voltage, head end phase current and terminal phase current;

Described head end phase voltage, head end phase current and terminal phase current according to measuring calculate tested transmission line of electricity positive sequence impedance and zero sequence impedance.

8, method according to claim 7 is characterized in that, when measuring the positive sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{X_1}{\mathrm{\&omega;}{X}_1^2+\mathrm{\&omega;}{R}_1^2}-\frac{C_1}{2}$

Wherein, C _XBe building-out capacitor; C ₁Be the discreet value of tested transmission line of electricity positive sequence electric capacity; Z ₁Be discreet value of tested transmission line of electricity positive sequence impedance and Z ₁=R ₁+ jX ₁

9, method according to claim 7 is characterized in that, when measuring the zero sequence impedance of UHV transmission line, described building-out capacitor value is:

$C_X=\frac{3X_0}{\mathrm{\&omega;}{X}_0^2+\mathrm{\&omega;}{R}_0^2}-\frac{3C_0}{2}$

Wherein, C _XBe building-out capacitor; C ₀Be the discreet value of tested transmission line of electricity zero sequence electric capacity, Z ₀Be discreet value of tested transmission line of electricity zero sequence impedance and z ₀=R ₀+ jX ₀

10, method according to claim 7 is characterized in that, before calculating tested transmission line of electricity positive sequence impedance and zero sequence impedance, further comprises:

The waveform of record head end phase voltage, head end phase current and terminal phase current.

11, method according to claim 10 is characterized in that, further comprises during the waveform of record head end phase voltage, head end phase current and terminal phase current:

Wave label GPS synchronous time mark to head end phase voltage, head end phase current and terminal phase current;

Waveform according to described synchronous time mark intercepting head end phase voltage, head end phase current and terminal phase current.

Images