CN1180271C - Apparatus and method for positioning parallel double electricity transmission line - Google Patents

Abstract

A method and an apparatus for a trouble-location on a transmission line of a concurrent double line are provided. The method includes the steps of: converting a three-phase voltage and current signal on the transmission line to a small signal; collecting and storing the converted voltage and current value as data; comparing the data with predetermined reference data to determine the trouble of the transmission line as well as trouble types; separating and obtaining the voltage and current data after and before the trouble responding the comparing step; performing trouble location algorithm for the obtained data based on a predetermined starting mode to get a current distribution factor, and caculating the trouble distance and trouble information at the trouble point by utilizing the current distribution factor.

Description

Parallel double electricity transmission line fault locator and method

Technical field

The present invention relates to a kind of transmission line fault locating device and method, particularly relate to a kind of can working as when on parallel (parallel) double electricity transmission line, earth fault and short circuit taking place by utilizing voltage and current information and self end current distribution factor to be positioned at the apparatus and method of the trouble spot on the parallel double electricity transmission line.

Background technology

Along with continuing to increase of power consumption, the variation, complicated more and carry out EHV transmission that becomes more of power transmission line system.In addition, the quick correct positioning of fault becomes more important aspect stable power-supplying, this be since by fast failure system is isolated fast with normal system, emergent restoring etc., can strengthen the reliability of electric power system.Therefore, Utilities Electric Co. moves some transmission line fault locating devices, these transmission line fault locating devices is installed so that correctly locate the fault that takes place on the power transmission line.

When single-phase or heterogeneous earth fault and short circuit, after the fault that self end one side that fault locator is installed in this fault locator utilization is therein measured by transformer station/preceding voltage and current, or utilize simultaneously after the fault that the other end one side is measured by transformer station/preceding voltage and current, so that calculate fault distance, and correspondingly according to result of calculation indication fault dot information apart from mounting points.

About this point, the conventional method of fault location point is divided into following two groups.

In first group of methods, receive the voltage and current signal from self end one side transformer station, in second group of methods, from self end one side transformer station be connected to the reception voltage and current information of the other end one side transformer station of the power transmission line of self end.

Be used in first group of methods of voltage and current information with fault location point of self end, utilizing power supply (power impedance) impedance of self end in one case, and do not utilize this impedance in other mode in other cases.About this point, utilizing under the situation of source impedance, can not be always constant from the source impedance that self end is watched, make to obtain wrong result, and numerical value is set can not proofreaies and correct all the time of variable source impedance.Therefore, in all conventional locating devices, no longer adopted the source impedance of self end till now.In other words, the problem that the Fault Locating Method of the source impedance that no longer adopts self end afterwards exists is, although these methods have compensated fault resstance and load, owing to the reason of the sensitivity of phase angle can not obtain the correct positioning result.

In second group of methods that is being used for obtaining voltage and current information, for localization of fault compares self end ratio with the voltage and current of the other end one side from the other end one side.According to these methods, although its advantage is a fault location more correctly, provide additional communication facilities and circuit, with after obtaining fault about the voltage and current value of the other end/preceding data.Consider the distance between the transformer station that is generally the 10-100 kilometer, be difficult to communication facilities is installed and circuit guarantees and additional communication path for the localization of fault between two ends.Therefore, the Fault Locating Method that is used to obtain the voltage and current data of the other end one side is to be difficult to adopt.

Therefore, the problem of only utilizing the fault locator of the routine of self client information to exist is may produce mistake in localization of fault.These mistakes be since in objective system, be difficult to the fault resstance that obtains with and the combination of the influence of the influencing each other of load current influence (reactive effect), zero element, zero phase sequence impedance mutually, atmosphere resistance.

The power transmission line system of Utilities Electric Co. is made up of three-phase list power transmission line system, three-phase parallel double electricity transmission line system and multi-terminal system, and power transmission line system nearly all in this multi-terminal system all moves with three-phase parallel double electricity transmission line system.When three-phase parallel double electricity transmission line system be in operation take place single-phase/during heterogeneous earth fault, produce zero phase of impedance according to the zero-phase-sequence current on non-fault line or the adjacent lines in the parallel double electricity transmission line that has broken down, make and have only when the adjacent lines input fault zero-phase-sequence current signal from parallel double electricity transmission line just fault location point correctly.Yet, Utilities Electric Co. can not be at the zero-phase-sequence current of parallel double electricity transmission line other acquisition adjacent lines in service up to now, therefore, need a kind of fault locator and method, zero-phase-sequence current just can prevent because the influence of the zero phase of impedance of the adjacent lines that zero-phase-sequence current causes though do not receive from the other end one side joint therein.

Summary of the invention

Proposing the present invention is for solving the problems referred to above of correlation technique, therefore the fault locator and the method that the purpose of this invention is to provide parallel double electricity transmission line, in three-phase parallel double electricity transmission line system during fault location point, by receiving the voltage or the electric current of self end, and needn't receive the zero-phase-sequence current fault location point correctly just of the adjacent lines of parallel transmission of electricity.

Another object of the present invention provides a kind of method that is used to obtain current distribution factor, this current distribution factor can be estimated the fault current and the zero-phase-sequence current of non-fault line and adjacent lines, under the situation that parallel double electricity transmission line breaks down, they are the significant variables that are used for correct localization of fault; And a kind of fault locator of parallel double electricity transmission line and method, wherein current distribution factor can be utilized so that propose fault location algorithm, and utilize the voltage and current information of self end for correct localization of fault, can get rid of the influence of background system impedance variation and trouble spot resistance simultaneously.

In order to reach above-mentioned purpose of the present invention, a kind of Fault Locating Method of parallel double electricity transmission line is provided, the step that comprises has: three-phase voltage on the power transmission line and current signal numerical value are converted to small-signal; Compile and store through the conversion voltage and current numerical value as data; Stored voltage and current data and the reference data that sets in advance are compared, to judge fault and the fault type on the power transmission line; If in response on the comparison step power transmission line fault being arranged, separate and obtain after the fault and preceding voltage and current data; Carry out fault location algorithm according to the originate mode that pre-sets according to the data of obtaining, obtaining current distribution factor, and by utilizing current distribution factor to calculate the failure message of fault distance and trouble spot; And the fault distance that calculated of storage and information and send the fault distance and the information of storage to the outside.

Best, in described separation and obtaining step, use and separate and obtain voltage and current data before the transmission line fault in 30 cycles and the voltage and current data after the fault in 60 cycles; And with current distribution factor be decomposed into zero, positive and negative phase-sequence current distribution coefficient, make and in each balancing circuitry, handle this voltage and current and in fault location algorithm, use, so that according to parallel double electricity transmission line fault type fault location point.

Description of drawings

Introduce each preferred embodiment of the present invention with reference to the accompanying drawings, wherein:

Fig. 1 is used to represent the structural drawing that is configured in the fault locator of a parallel double electricity transmission line on the power transmission line according to of the present invention;

Fig. 2 is the calcspar according to fault locator of the present invention;

Fig. 3 is the detailed block diagram according to main control unit of the present invention;

Fig. 4 is the process flow diagram that is used to describe according to Fault Locating Method of the present invention;

Fig. 5 A be according to of the present invention under the situation that earth fault takes place on the power transmission line detail flowchart of fault location algorithm;

Fig. 5 B be according to of the present invention under the situation that three-phase earth fault/short circuit takes place on two power transmission lines the detail flowchart of fault location algorithm;

Fig. 6 A to 6B be used to represent according to before the fault on the parallel double electricity transmission line of the present invention and after the circuit diagram of impedance variation;

Fig. 7 A to 7C is used to obtain because the circuit diagram of the distribute power coefficient that zero phase-sequence, positive phase sequence and negative-phase sequence form according to of the present invention;

Fig. 8 is the circuit diagram that is used to represent the system when on the parallel double electricity transmission line of the present invention a power transmission line earth fault taking place;

Fig. 9 is the circuit diagram that is used to represent the system when between power transmission line three-phase shortcircuit taking place on the parallel double electricity transmission line of the present invention; And

Figure 10 is the circuit diagram that is used to represent the system when on the parallel double electricity transmission line of the present invention two power transmission line ground short circuits and three-phase shortcircuit taking place.

Embodiment

Fig. 1 is used to represent the structural drawing that is configured in the fault locator of a parallel double electricity transmission line on the power transmission line according to of the present invention.

With reference to Fig. 1, apply voltage and current signal to fault locator E from principal voltage mutual inductor C on this power transmission line and main current mutual-inductor B, measure transmission line fault and fault distance according to corresponding fault location algorithm.In addition, provide the digital signal of indication fault to fault locator E from protective relay D1, and according to before the corresponding transmission line fault and after information calculate.About this point, fault distance is meant the distance from the mounting points of main current mutual-inductor to trouble spot P.

Apply voltage and current signal to protective relay D1 from principal voltage mutual inductor C and main current mutual-inductor B; detect fault on the power transmission line apace according to the voltage and current signal that applies, and control power transmission line break device A is not subjected to fault effects with the protection power transmission line.

Fig. 2 is the calcspar according to fault locator of the present invention;

With reference to Fig. 2, fault locator comprises: auxiliary potential transformer 100, auxiliary current transformer 120, data collection unit 200, data storage cell 280, main control unit 300, I/O unit 400, storage unit 600 and correction and display unit 500.

Data collection unit 200 comprises: signal conditioning unit 220 low-pass filters 240 and A/D converting unit 260.

Provide three-phase voltage by the principal voltage mutual inductor C that is installed in the electric system to auxiliary potential transformer 100, auxiliary potential transformer 100 is converted to the signal of small voltage with this three-phase voltage, to send to hereinafter with the data collection unit of introducing 200.

Provide three-phase current by the main current mutual-inductor B that is installed in the supply line to auxiliary current transformer 120, auxiliary current transformer 120 is converted to the signal of less electric current with this three-phase current, to send to hereinafter with the data collection unit of introducing 200.

Data collection unit 200 utilize signal conditioning unit 220 regulate the signal of the small voltage that sends from auxiliary potential transformer 100 and the signal of the less electric current that sends from auxiliary current transformer 120 they are provided to hereinafter with the low-pass filter of introducing 240.

Low-pass filter 240 high fdrequency component is provided from the voltage and current signal that is provided and is sent to A/D converting unit 260 by filtering operation.A/D converting unit 260 is signal digitalized and be provided to data storage cell 280 with the voltage and current of input.Data storage cell 280 storages also are provided to main control unit 300 with this signal from the voltage and current digital signal that A/D converting unit 260 provides.

Main control unit 300 is by being used to judge from the digitized three-phase voltage and the current data of data storage cell 280 whether power transmission line has fault, and by after separating and obtaining fault/preceding voltage and current information obtains current distribution factor, the fault distance when breaking down with calculating.To introduce the operation about calculating current distribution factor and fault distance of main control unit 300 in detail below with reference to Fig. 3.

Provide failure indication information on the power transmission line from protective relay D1 to I/O unit 400, whether break down on I/O unit 400 notice main control units, 300 power transmission lines.I/O unit 400 also receives the information of the fault on the power transmission line that corresponding relay detects from protective relay D1, this protective relay D1 action power transmission line break device A, and from external notification by failure judgement point calculating fault distance.Failure message and fault distance data that storage unit 600 storages are differentiated by main control unit 300.Proofread and correct and display unit 500 can be used as the information of benchmark when proofreading and correct on determining power transmission line various fault, and externally show fault distance and information.

Fig. 3 is the detailed block diagram according to main control unit of the present invention.

With reference to Fig. 3, main control unit 300 comprises: data are compiled with storage unit 310, benchmark unit 315, fault judgement unit 320, data separating and acquiring unit 330, current distribution factor computing unit 340, fault distance computing unit 350, failure message processing unit 360, storage unit 370, failure message display unit 380 and external communications units 390 are set.

Benchmark is provided with unit 315 according to earth fault on the power transmission line and short circuit, the reference information that storage failure is judged, and this information is provided to hereinafter with the fault judgement unit of introducing 320.Data are compiled and are compiled with storage unit 310 and digitized three-phase voltage and the current data that provides from data storage cell 280 is provided, and are provided to fault judgement unit 320.Fault judgement unit 320 is with reference to compile the voltage and current data of importing with storage unit 310 from data, judge fault on the power transmission line according to the benchmark that some fault judgement that unit 315 provides are set from benchmark, and its result is sent to data separating and acquiring unit 330.Data separating and acquiring unit 330 are when receiving the fault generation signal that produced by fault judgement unit 320 or during from the fault generation information of I/O unit 400, separate and obtain voltage and current data before the transmission line fault in 30 cycles and the voltage and current data after the fault in 60 cycles, and the information of being obtained is sent to current distribution factor computing unit 340.Here, 1 cycle be 1.66 milliseconds corresponding to 60 hertz.

After the fault of current distribution factor computing unit 340 receptions by data separating and acquiring unit 330 transmissions/preceding voltage and current data, and according to the voltage and current data computation current distribution factor of importing, and be provided to fault distance computing unit 350.Here, calculate current distribution factor about non-fault line and the other end one side line road expression formula, be introduced with reference to Fig. 4 by determining a voltage equation according to given data and obtaining one according to this equation.

Failure message processing unit 350 calculates the distance of physical fault point according to the current distribution factor that is provided by current distribution factor computing unit 340 by the expression formula that obtains fault distance, and the physical fault range data of being calculated is sent to failure message processing unit 360.

Failure message processing unit 360 receive from the fault distance data of failure message processing unit 350 and from data separating and acquiring unit 330 for example be fault after/failure message of preceding data, and the data that received are sent to storage unit 370.In addition, failure message processing unit 350 by proofread and correct and display unit 500 show from the fault distance data of failure message processing unit 350 and data separating and acquiring unit 330 with comprise fault after/the various information of preceding information.Storage unit 370 storage institute's calculated distance information and failure messages, and failure message display unit 380 provides institute's calculated distance information through overcorrect and display unit 500 to the user.Failure message processing unit 360 and external communications units 390 unit communication are to send to outer computer or principal computer with institute's calculated distance information and failure message.

Here, will introduce the method for localization of fault according to said structure in detail with reference to Fig. 4.

At first, when fault locator is finished its initialization, at first at step S100, through outside principal voltage mutual inductor and main current mutual-inductor three-phase voltage on the power transmission line and electric current are reduced respectively, and be the small-signal of voltage and current with three-phase voltage and current conversion through reducing through auxiliary potential transformer 100 and auxiliary current transformer 120.

Utilizing signal conditioning unit 220 to be adjusted in step S100 is converted to the small-signal of voltage and current and is provided to low-pass filter 240.Then, at step S120, low-pass filter 240 is removed high fdrequency component from the voltage and current signal of input, and at step S140, carries out low-pass filtering by the DFT (discrete Fourier transformation) that utilizes 1 cycle.

In other words, three-phase voltage and electric current that digitized signal that will be in A/D converting unit 260 quantizes in according to RTTS send to data storage cell 280.Here, sample by the real-time three-phase voltage and the electric current of 14 or 16 pairs of quantifications according to 600 hertz voltage and current signal.

To be (root-mean-square value) RMS in the voltage and current calculated signals that step S140 utilizes DFT filtering to detect, the voltage and current signal that will be calculated as RMS according to UVR (under-voltage replay device), OCGR (excess current grounding relay device) and the OCR (overcurrent relay device) of pre-indication compares, to judge transmission line fault at step S160 with at step S180.

Here, the voltage of relay-set receiving system or electric current, and, calculate and be output as the signal of " 0 " or " 1 " by input value arithmetic operation according to preassignment.

Therefore, when UVR moved, whether the big or small maximum of the input voltage on the identification system was preset reference value (corrected value).When system breaks down, start OCGR, and judge whether that the earth-fault current of importing is preconditioning reference value or corrected value at least by the detection of ground faults electric current or along the zero-phase-sequence current that the earth flows.OCR judges whether that system's phase current of importing is preconditioning reference value or the corrected value about its operation at least.

Therefore, at step S180, generate as pressing the voltage and current information that RMS calculates, if the generation electric current of input is the formation voltage of the reference value of OCR and input at least is that reference value or the zero-phase-sequence current of UVR is the reference value of OCGR at least at least, then trip, so that at step S200 and step S220, fault judgement unit 320 failure judgement phase and fault type.

Here, judge that whether current status is because the fault that power transmission line earth fault and short circuit form, and in fault is judged mutually, fault type differentiated and be single-line ground fault, two-wire short circuit, double line ground fault, three-phase earth fault and three-phase shortcircuit.

In step S220, finish after the failure judgement type, by utilizing the bus voltage and the current data of input, after separating and obtaining fault/preceding data.In other words, at step S240, data separating is separated with acquiring unit 330 and is obtained voltage and current data before the transmission line fault in 30 cycles and the voltage and current data after the fault in 60 cycles.

Simultaneously,, obtain after the front/rear data of transmission line fault,, judge whether originate mode is outside originate mode at step S260 at step S240.Here, if the result who provides at step S260 is outside originate mode, then confirm whether be a DI contact, if and originate mode is the internal triggering pattern, then, utilize current distribution factor computing unit 340 and fault distance computing unit 350 to calculate fault distance according to fault location algorithm at step S300.

Here, originate mode is provided with carries out for which fault location algorithm, and when carrying out fault location algorithm according to the failure message of importing from protective relay A outside, judges whether the tripping operation information of protective relay A is input to this device.When confirming the DI contact, confirm the input port whether failure message is input to the DI in the fault locator.The internal triggering pattern is meant according to the failure message that is detected by fault locator itself carries out fault location algorithm.

Here, will introduce fault location algorithm with reference to Fig. 6 to 10.

At step S340 and step S360, utilize failure message and the fault distance of failure message processing unit 360 outputs by aforementioned fault location algorithm metering, and being stored in storage unit 370, this operation turns back to step S100 then, receives the instantaneous value of voltage and current.

Before open each fault location algorithm, introduce term and the symbol that is used in the circuit in using below according to fault wire.

When parallel double electricity transmission line breaks down, the distribution of current of faulty circuit is to change according to the distribution of impedance in the system, as shown in Fig. 6 B.Circuit among Fig. 6 A is represented the state before the fault, and the circuit among Fig. 6 B is represented the state after the fault.Therefore, need fault after/preceding information so that in order to proofread and correct these circuit of fault locating analysis.

The data of storage are used for the distribution of impedance of the circuit that the voltage and current data are formed after information needed before the fault and the fault in the storage unit 370, so that predict the fault current and the zero-phase-sequence current of non-fault wire.Here, fault current is the electric current that is included in when producing earth fault and short circuit on the circuit of transmission system in the fault resstance of arc resistance that the trouble spot produces and contact point resistance.

Non-fault line is meant the circuit of the power supply of the system in this parallel double electricity transmission line stably, the adjacent circuit of the faulty line with earth fault or short circuit wherein take place that does not promptly break down.

Be applied to current distribution factor of the present invention be meant with at the corresponding impedance ratio of the electric current degree of correlation of the electric current degree of correlation of self end of faulty line and the other end one side corresponding impedance ratio, faulty line and non-fault line etc., and according to correspondence be categorized as zero mutually, the positive and negative phase sequence.

When for example representing voltage (electric current) for zero, the positive and negative phase sequence of Va (Ia), Vb (Ib) and Vc (Ic) according to symmetrical coordinates in asymmetric unbalanced three-phase circuit, each in them can be expressed as according to the symmetrical components of V1, V2 and V0:

Va=V ₀+ V ₁+ V ₂, Vb=V ₀+ a ²V ₁+ aV ₂, Vc=V ₀+ aV ₁+ a ²V ₂With

Ia＝I ₀+I ₁+I ₂，Ib＝I ₀+a ²I ₁+aI ₂，I _c＝I ₀+aI ₁+a ²I ₂，

Wherein,

With

1+a+a ²＝0

Here, V ₀(I ₀) be called zero phase sequence voltage (electric current), as the common single-phase component that is included in A, B and C phase voltage and the electric current.

For V ₁(I ₁), A has V mutually ₁(I ₁); B has a mutually ²V ₁(a ²I ₁), V is compared in representative ₁(I ₁) 120 ° (or leading 240 °) lag behind; Has aV mutually with C ₁(aI ₁), V is compared in representative ₁(I ₁) leading 120 ° (or lagging behind 240 °).In other words, at V ₁(I ₁), this voltage (electric current) is called positive phase sequence voltage (electric current), because it has and the identical sense of rotation of balanced three-phase voltage (electric current) about A, B and C phase.

In addition, for V ₂(I ₂), A has V mutually ₂(I ₂); B has aV mutually ₂(aI ₂), it compares V ₂(I ₂) leading 120 ° (or lagging behind 240 °); Has a mutually with C ²V ₂(a ²I ₂), it compares V ₂(I ₂) 120 ° (or leading 240 °) lag behind.In other words, at V ₂(I ₂), this voltage (electric current) is called negative phase sequence voltage (electric current) because its have with about A, B and the C opposite sense of rotation of balanced three-phase voltage (electric current) mutually.

Here, be defined in the symbol that uses in each electrical equipment according to following table 1:

Table 1

Symbol	Definition	Unit
			Z S0	The zero phase sequence impedance of power supply SS	[Europe]
Z S1	The positive-phase-sequence impedance of power supply SS	[Europe]
			Z S2	The negative phase sequence impedance of power supply SS	[Europe]
Z R0	The zero phase sequence impedance of power supply SR	[Europe]
			Z R1	The positive-phase-sequence impedance of power supply SR	[Europe]
Z R2	The negative phase sequence impedance of power supply SR	[Europe]
			Z L0	The zero phase sequence impedance of faulty line	[Europe]
Z L1	The positive-phase-sequence impedance of faulty line	[Europe]
			Z L2	The negative phase sequence impedance of faulty line	[Europe]
Z T0	The zero phase sequence impedance of non-fault line	[Europe]
			Z T1	The positive-phase-sequence impedance of non-fault line	[Europe]
Z T2	The negative phase sequence impedance of non-fault line	[Europe]
			R f	Trouble spot resistance	[Europe]
I S0	The zero-phase-sequence current of self end	[peace]
			I S1	The positive-phase-sequence current of self end	[peace]
I S2	The negative phase sequence current of self end	[peace]

I R0	The zero-phase-sequence current of the other end	[peace]
			I R1	The positive-phase-sequence current of the other end	[peace]
I R2	The negative phase sequence current of the other end	[peace]
			I T0	The zero-phase-sequence current of non-fault line	[peace]
I T1	The positive-phase-sequence current of non-fault line	[peace]
			I T2	The negative phase sequence current of non-fault line	[peace]
I f0	Zero-phase-sequence current towards the trouble spot	[peace]
			I f1	Positive-phase-sequence current towards the trouble spot	[peace]
I f2	Negative phase sequence current towards the trouble spot	[peace]
			P	Distance from the relay mounting points to the trouble spot	[normalized value]

Below, when breaking down on power transmission line, the symmetrical components circuit that is used to obtain the faulty circuit of current distribution factor is constructed as follows:

Fig. 7 A represents to be used to obtain the zero phase-sequence circuit of current distribution factor.In the zero phase-sequence circuit shown in Fig. 7 A, utilize equation 1 to obtain two voltage equations along path A and B:

(Z _S0+pZ _L0)I _S0-[Z _R0+(1-p)Z _L0]I _R0+(Z _S0+Z _R0+Z _m)I _T0＝0

(Z _S0+pZ _m)I _S0-[Z _R0+(1-p)Z _m]I _R0+(Z _S0+Z _R0+Z _T0)I _T0＝0

... equation 1

In equation 1, if the zero-phase-sequence current I of cancellation non-fault line _T0, utilize equation 2 to obtain zero-phase-sequence current I in self end _S0With the zero-phase-sequence current I in the other end _R0The ratio of distribution of current:

$\frac{I_{R0}}{I_{S0}}=\frac{(Z_{T0}-Z_m)Z_{S0}+p{Z}_{L0}(Z_{S0+}{Z}_{R0}+Z_{T0})-p{Z}_m(Z_{S0}+Z_{R0}+Z_m)}{(Z_{T0}-Z_m)Z_{R0}+(1-p)Z_{L0}(Z_{S0}+Z_{R0}+Z_{T0})-(1-p)Z_m(Z_{S0}+Z_{R0}+Z_m)}$

... equation 2

Here, owing to the electric current that flows through the trouble spot is I _F0=I _S0+ I _R0, utilize equation 3 to obtain the zero-phase-sequence current distribution coefficient:

$D_{\mathrm{Sa}0}=\frac{I_{S0}}{I_{f0}}=\frac{I_{S0}}{I_{S0}+I_{R0}}=\frac{1}{1+(I_{R0}/I_{S0})}=\frac{p{B}_{\mathrm{Sa}0}+C_{\mathrm{sa}0}}{A_{\mathrm{Sa}0}}$

... equation 3

Wherein,

A _Sa0＝(Z _L0-Z _m)(Z _S0+Z _R0+Z _m)+(Z _T0-Z _m)(Z _S0+Z _R0+Z _L0)

B _Sa0=(Z _m-Z _L0) (Z _S0+ Z _R0+ Z _m)-(Z _T0-Z _m) Z _L0And

C _Sa0＝(Z _L0-Z _m)(Z _S0+Z _R0+Z _m)+(Z _T0-Z _m)(Z _R0+Z _L0)

Therefore, if from equation 1 the zero-phase-sequence current I of cancellation in other side _R0To obtain the zero-phase-sequence current distribution coefficient of non-fault line, utilize equation 4 to obtain the zero-phase-sequence current I of self end _S0Zero-phase-sequence current I with other side _T0The ratio of distribution of current:

$D_{\mathrm{TS}}=\frac{I_{S0}}{I_{T0}}=\frac{p{A}_{\mathrm{ST}}+B_{\mathrm{ST}}}{p{C}_{\mathrm{ST}}+D_{\mathrm{St}}}$

... equation 4

Wherein,

A _ST＝(Z _m-Z _L0)(Z _S0+Z _R0+Z _m)-(Z _T0-Z _m)Z _L0

B _ST＝(Z _L0-Z _m)(Z _S0+Z _R0+Z _m)+(Z _T0-Z _m)(Z _R0+Z _L0)

C _ST=(Z _L0-Z _m) (Z _S0+ Z _R0) and

D _ST＝(Z _m-Z _L0)Z _S0<1P>

Therefore, in step S302 and step S304, utilize equation 5, obtain the zero-phase-sequence current distribution coefficient of non-fault line from above-mentioned equation 3 and 5:

$D_{T0}=\frac{I_{T0}}{I_{f0}}=\frac{p{B}_{T0}+C_{T0}}{A_{T0}}$

... equation 5

Wherein,

A _T0＝(Z _L0-Z _m)(Z _S0+Z _R0+Z _m)+(Z _T0-Z _m)(Z _S0+Z _R0+Z _m)

B _T0＝(Z _L0-Z _m)(Z _S0+Z _R0)

C _T0＝(Z _m-Z _L0)Z _S0<1P>

Then, as follows with reference to obtaining the positive-phase-sequence current distribution coefficient at the positive phase sequence circuit shown in Fig. 7 B:

Set up voltage equation shown in equation 6 according to method positive-phase-sequence current distribution coefficient same as described above:

(Z _S1+pZ _L1)I _S1-[Z _R1+(1-p)Z _L1]I _R1+(Z _S1+Z _R1)I _T1＝0

Z _S1I _S1-Z _R1I _R1+(Z _S1+Z _R1+Z _T1)I _T1＝0

... equation 6

Here, utilize equation 7 to obtain electric current I _S1With electric current I _R1The ratio of distribution of current:

$\frac{I_{R1}}{I_{S1}}=\frac{Z_{S1}{\mathrm{<figure-callout\; id="1"\; label="Z\; T"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Z</figure-callout>}}_T+p{Z}_{L1}({\mathrm{<figure-callout\; id="1"\; label="Z\; S"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Z</figure-callout>}}_S+{\mathrm{<figure-callout\; id="1"\; label="Z\; R"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Z</figure-callout>}}_R+Z_{T1})}{Z_{R1}{\mathrm{<figure-callout\; id="1"\; label="Z\; T"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Z</figure-callout>}}_T+(1-p)Z_{L1}({\mathrm{<figure-callout\; id="1"\; label="Z\; S"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Z</figure-callout>}}_S+{\mathrm{<figure-callout\; id="1"\; label="Z\; R"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Z</figure-callout>}}_R+Z_{T1})}$

... equation 7

Here, owing to the electric current that flows through the trouble spot is I _F1=I _S1+ I _R1, therefore, utilize equation 8 to obtain the positive-phase-sequence current distribution coefficient:

${\mathrm{<figure-callout\; id="1"\; label="D\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">D</figure-callout>}}_{\mathrm{Sa}}=\frac{I_{S1}}{{\mathrm{<figure-callout\; id="1"\; label="I\; f"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">I</figure-callout>}}_f}=\frac{I_{S1}}{{\mathrm{<figure-callout\; id="1"\; label="I\; S"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">I</figure-callout>}}_S+I_{R1}}=\frac{1}{1+(I_{R1}/I_{S1})}\frac{\mathrm{<figure-callout\; id="1"\; label="p\; B\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">p</figure-callout>}{B}_{\mathrm{Sa}}{1}_{}+C_{\mathrm{sa}1}}{A_{\mathrm{<figure-callout\; id="1"\; label="Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Sa</figure-callout>}1}}$

... equation 8

Wherein,

A _Sa1＝Z _L1(Z _S1+Z _R1)+Z _T1(Z _S1+Z _R1+Z _L1)

B _Sa1=Z _L1(Z _S1+ Z _R1+ Z _T1) and

C _Sa1＝Z _L1(Z _S1+Z _R1+Z _T1)+Z _T1Z _R1

Then, reference obtains the negative phase sequence current distribution coefficient at the negative-phase sequence circuit shown in Fig. 7 C, and is as follows:

Utilize equation 9 to obtain negative phase sequence current distribution coefficient in the negative-phase sequence circuit according to the method identical with above-mentioned positive-phase-sequence current:

$D_{\mathrm{Sa}2}=\frac{I_{S2}}{I_{f2}}=\frac{p{B}_{\mathrm{Sa}2}+C_{\mathrm{sa}2}}{A_{\mathrm{Sa}2}}$

... equation 9

Wherein,

A _Sa2＝Z _L2(Z _S2+Z _R2)+Z _T2(Z _S2+Z _R2+Z _L2)

B _Sa2=Z _L2(Z _S2+ Z _R2+ Z _T2) and

C _Sa2＝Z _L2(Z _S2+Z _R2+Z _T2)+Z _T2Z _R2

Here, if positive-phase-sequence impedance is identical with negative phase sequence impedance, utilize equation 10 to obtain positive-phase-sequence current distribution coefficient and negative phase sequence current distribution coefficient:

D _Sa1＝D _Sa2

A _Sa1＝A _Sa2，B _Sa1＝B _Sa2，C _Sa1＝C _Sa2

... equation 10

Simultaneously, with reference to the parallel double electricity transmission line Fault Locating Method of Fig. 8 to 10 introduction according to various fault types, these methods utilizations are zero, positive and negative phase-sequence current distribution coefficient is as follows according to above-mentioned separate equation:

Fig. 5 A is the detail flowchart that earth fault takes place on a power transmission line in the fault location algorithm shown in Fig. 4.This Fault Locating Method can be represented with main 3 kinds of modes, wherein will be presented in the Fault Locating Method that utilizes above-mentioned zero phase-sequence equation under the situation that earth fault takes place on the power transmission line in this application.

Wherein be presented under the situation that earth fault takes place on the power transmission line, utilize the zero phase-sequence equation in the Fault Locating Method 2 with reference to Fig. 8.

Among Fig. 8, utilize equation 11 to obtain voltage after the fault:

V _Sa＝p[Z _L1I _Sa+(Z _L0-Z _L1)I _S0]+pZ _mI _T0+R _fI _f

... equation 11

Wherein,, utilize equation 16 to obtain voltage equation, to the electric current of S304 cancellation non-fault line and the electric current of side in addition, calculate the zero-phase-sequence current distribution coefficient at step S302 in the relay mounting points at step S301.

According to above-mentioned equation, use zero-phase-sequence current and zero-phase-sequence current distribution coefficient in the relay mounting points, so that utilize equation 12 to obtain voltage equation in the relay mounting points at step S305:

$V_{\mathrm{Sa}}=p[Z_{L1}{I}_{\mathrm{Sa}}+(Z_{L0}-Z_{L1})I_{S0}]+p{Z}_m\frac{I_{S0}}{D_{\mathrm{TS}}}+R_f\frac{3I_{S0}}{D_{\mathrm{Sa}0}}$

Equation 12

At step S306, the voltage equation that will set up according to equation 12 with each current distribution factor value corresponding substitution.Then, utilize equation 13 to be expressed in the voltage equation of relay mounting points:

$V_{\mathrm{Sa}}=p[Z_{L1}{I}_{\mathrm{Sa}}+(Z_{L0}-Z_{L1})I_{S0}]+p{Z}_m{I}_{S0}\frac{p{C}_{\mathrm{ST}}+D_{\mathrm{ST}}}{p{A}_{\mathrm{ST}}+B_{\mathrm{ST}}}+3R_f{I}_{S0}\frac{A_{\mathrm{Sa}0}}{p{B}_{\mathrm{Sa}0}+C_{\mathrm{Sa}0}}$

Equation 13

Wherein, owing to pA in equation 4 and 5 _ST+ B _ST=pB _Sa0+ C _Sa0, they are taken as a common denominator and treat.Therefore, utilize equation 14 to reach at the voltage table of relay mounting points:

$V_{\mathrm{Sa}}=p[Z_{L1}{I}_{\mathrm{Sa}}+(Z_{L0}-Z_{L1})I_{S0}]+\frac{[p{Z}_m{I}_{S0}(p{C}_{\mathrm{ST}}+D_{\mathrm{ST}})+3R_f{I}_{S0}{A}_{\mathrm{Sa}0}]}{p{B}_{\mathrm{Sa}0}+C_{\mathrm{Sa}0}}$

Equation 14

At step S307, each coefficient of this formula that replaces is also put in order about fault distance p, to obtain 15 equations:

(a ₁+jb ₁)p ²+(a ₂+jb ₂)p+(a ₃+jb ₃)+(a ₄+jb ₄)R _f＝0

Equation 15

Wherein

a ₁+jb ₁＝[Z _L1I _Sa+(Z _L0-Z _L1)I _S0]B _Sa0+Z _mI _S0C _ST

a ₂+jb ₂＝[Z _L1I _Sa+(Z _L0-Z _L1)I _S0]C _Sa0+Z _mI _S0D _ST-V _SaB _Sa0

a ₃+jb ₃＝-V _SaC _Sa0

a ₄+jb ₄＝3I _S0A _Sa0

Wherein,, decompose the equation of forming by real part and imaginary part 15 at step S308, so that obtain equation 16:

a ₁p ²+a ₂p+a ₃+a ₄R _f＝0

b ₁p ²+b ₂p+b ₃+b ₄R _f＝0

Equation 16

At step S309, at cancellation fault resstance R _fBy the quadratic expression in the equation 17 (quadratic equation) that utilizes, obtain fault distance p later on:

$(a_1-b_1\frac{a_4}{b_4})p^2+(a_2-b_2\frac{a_4}{b_4})p(a_3-b_3\frac{a_4}{b_4})=0$

... equation 17

At step S310 and step S311, obtain two roots by equation 17, wherein because total line length is made as 1, therefore, fault distance p is a numerical value 0 to 1.

Simultaneously, with reference to the circuit of a line-to-ground fault shown in Fig. 8, be presented in the Fault Locating Method under the situation of a line-to-ground fault.

Because it is identical flowing to zero, the positive and negative phase-sequence current of trouble spot, this electric current can utilize at the electric current and the current distribution factor of relay mounting points according to equation 18 and express.

In system shown in Fig. 8, utilize equation 18, the situation current downflow of a line-to-ground fault to the reometer of trouble spot be shown zero, the positive and negative phase sequence:

I _f0＝I _f1＝I _f2

... equation 18

By means of electric current and the current distribution factor in the relay mounting points, equation 18 can be expressed with equation 19:

$\frac{I_{\mathrm{Sa}0}}{D_{\mathrm{Sa}0}}=\frac{I_{\mathrm{Sa}1}}{{\mathrm{<figure-callout\; id="1"\; label="D\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">D</figure-callout>}}_{\mathrm{Sa}}}=\frac{I_{\mathrm{Sa}2}}{D_{\mathrm{Sa}2}}$

... equation 19

In equation 19, if develop zero phase-sequence to positive phase sequence, zero phase-sequence to negative-phase sequence and positive phase sequence relational expression to negative-phase sequence, each relational expression is expressed (hereinafter will be called fault distance p) with the function apart from p from the relay mounting points to the trouble spot.

Here, if arrangement obtains fault distance p about the zero phase-sequence of p and the relational expression of zero-phase-sequence current distribution coefficient according to equation 14.

I _Sa0D _Sa1＝I _Sa1D _Sa0

... equation 20, and

$p=\frac{A_{\mathrm{Sa}1}{I}_{\mathrm{Sa}1}{C}_{\mathrm{Sa}0}-A_{\mathrm{Sa}0}{I}_{\mathrm{Sa}0}{C}_{\mathrm{Sa}1}}{A_{\mathrm{Sa}0}{I}_{\mathrm{Sa}0}{B}_{\mathrm{Sa}1}-A_{\mathrm{Sa}1}{I}_{\mathrm{Sa}1}{B}_{\mathrm{Sa}0}}$

... equation 21

Then, if positive-phase-sequence impedance is identical with negative phase sequence impedance, utilize equation 21 to obtain fault distance p in the relational expression of zero phase-sequence and zero-phase-sequence current distribution coefficient.

At last, arrangement is about the relational expression of positive phase sequence and the negative-phase sequence of fault distance p, to obtain equation 22:

$p=\frac{A_{\mathrm{Sa}1}{I}_{\mathrm{Sa}1}{C}_{\mathrm{Sa}2}-A_{\mathrm{Sa}2}{I}_{\mathrm{Sa}2}{C}_{\mathrm{Sa}1}}{A_{\mathrm{Sa}2}{I}_{\mathrm{Sa}2}{B}_{\mathrm{Sa}1}-A_{\mathrm{Sa}1}{I}_{\mathrm{Sa}1}{B}_{\mathrm{Sa}2}}=\frac{\left(A_{\mathrm{Sa}1}{C}_{\mathrm{Sa}1}\right)(I_{\mathrm{Sa}1}-I_{\mathrm{Sa}2})}{\left(A_{\mathrm{Sa}1}{B}_{\mathrm{Sa}1}\right)(I_{\mathrm{Sa}2}-I_{\mathrm{Sa}1})}$

Equation 22

Here, if positive-phase-sequence impedance is identical with negative phase sequence impedance, the positive-phase-sequence current distribution coefficient in equation 10 is identical with the negative phase sequence current distribution coefficient, and then electric current is identical, makes that fault distance p can not be by equation 22 definition.In other words, can not use the relational expression of positive phase sequence and negative phase sequence current distribution coefficient.

Then, utilize the positive phase sequence in the Fault Locating Method 2 under the situation of a circuit generation earth fault, equation becomes as follows:

When utilizing positive-phase-sequence current and positive-phase-sequence current distribution coefficient, set up voltage equation in the relay mounting points as equation 23:

V _Sa＝p[Z _L1I _Sa+(Z _L0-Z _L1)I _S0]+pZ _mI _T0+R _fI _f

Equation 23

Wherein, owing to flow to the electric current I of the non-fault line of trouble spot _fWith zero-phase-sequence current I _T0Not known, therefore, utilize zero-phase-sequence current and zero-phase-sequence current distribution coefficient in the relay mounting points.In addition, because I _fCan utilize zero, positive and negative phase-sequence current expression, use I _fSo that obtain 3 equations according to equation 23.

In addition, according to above-mentioned equation 23, utilize equation 24 to express positive-phase-sequence current and positive-phase-sequence current distribution coefficient:

$V_{\mathrm{Sa}}=p[Z_{L1}{I}_{\mathrm{Sa}}+(Z_{L0}-Z_{L1})I_{S0}]</P><P>+p{Z}_m\frac{I_{S0}}{D_{\mathrm{TS}}}+R_f\frac{3I_{S1}}{{\mathrm{<figure-callout\; id="1"\; label="D\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">D</figure-callout>}}_{\mathrm{Sa}}}$

Equation 24

With reference to Fig. 5 A to the circuit shown in the 5C, because fault current I _fBe that circuit after the fault produces I _S1Be pure phase fault electric current, cancellation the load current in the circuit before the fault in the equation 24.

Therefore, each coefficient that replaces is also put each relational expression about fault distance p in order, so that obtain equation 25 as cubic equation:

(a ₃+jb ₃)p ³+(a ₂+jb ₂)p ²+[a ₁+jb ₁+(c ₁+jd ₁)R _f]p

+[a ₀+jb ₀+(c ₀+jd ₀)R _f]＝0

Equation 25

Wherein

a ₃+jb ₃＝IZ _L1B _Sa1A _ST+I _S0Z _mB _Sa1C _ST

a ₂+jb ₂＝IZ _L1B _Sa1B _ST+IZ _L1C _Sa1A _ST

-V _SaB _Sa1A _ST+I _S0Z _mB _Sa1D _ST+I _S0Z _mC _Sa1C _ST

a ₁+jb ₁＝IZ _L1C _Sa1B _ST

-V _SaB _Sa1B _ST-V _SaC _Sa1A _ST+I _S0Z _mC _Sa1D _ST

a ₀+jb ₀＝-V _SaC _Sa1B _ST

c ₁+jd ₁＝3I _S1A _Sa1A _ST

c ₀+jd ₀＝3I _S1A _Sa1C _ST

$I=I_{\mathrm{Sa}}+\frac{(Z_{L0}-Z_{L1})}{Z_{L1}}{I}_{S0}$

Equation 25 is divided into real part and imaginary part, so that obtain equation 26 as two cubic equations:

a ₃p ³+a ₂p ²+(a ₁+c ₁R _f)p+(a ₀+c ₀R _f)＝0

b ₃p ³+b ₂p ²+(b ₁+d ₁R _f)p+(b ₀+d ₀R _f)＝0

Equation 26

Here, cancellation fault resstance R _f, so that obtain the equation 27 as biquadratic equation about fault distance p:

p ⁴+k ₁P ³+k ₂P ²+k ₃P ³+k ₄＝0

Equation 27

Wherein

k ₁＝(a ₂d ₁-b ₂c ₁+a ₃d ₀-b ₃+b ₀c ₀)/(a ₃d ₁-b ₃c ₁)，

k ₂＝(a ₁b ₁-b ₁c ₁+a ₂d ₂-b ₂c ₀)/(a ₃d ₁-b ₃c ₁)，

k ₃＝(a ₀d ₁-b ₀c ₁+a ₁d ₀-b ₁c ₀)/(a ₃d ₁-b ₃c ₁)，

k ₄＝(a ₀d ₀-b ₀c ₀)/(a ₃d ₁-b ₃c ₁).

Here, by utilizing the newton-La Fusen iterative computation in the equation 26, obtain fault distance p by the quadratic expression that utilizes the biquadratic equation in the equation 27.

In other words, by utilizing this quadratic expression the arrangement of the biquadratic equation in the equation 27 is the quadratic equation about fault distance, so that calculate fault distance.

Introduce the Fault Locating Method 3 of earth fault below with reference to Fig. 8.

To 5C, is pure fault current I at the electric current of relay mounting points with reference to Fig. 5 A _SafWith load current I _SaLAnd.They utilize equation 28 to express:

I _Sa＝I _Saf+I _SaL

Equation 28

Equation 28 is updated to voltage equation 11 in the relay mounting points, so that obtain equation 29:

V _Sa＝p[Z _L1(I _Saf+I _SaL)+(Z _L0-Z _L1)I _S0]+pZ _mI _T0+R _fI _f

Equation 29

Here, the both sides of equation 29 are all divided by I _SafSo that obtain equation 30:

$\frac{V_{\mathrm{Sa}}}{I_{\mathrm{Saf}}}=p[Z_{L1}(1+\frac{I_{\mathrm{SaL}}}{I_{\mathrm{Saf}}})+(Z_{L0}-Z_{L1})\frac{I_{S0}}{I_{\mathrm{Saf}}}]+p{Z}_m\frac{I_{T0}}{I_{\mathrm{Saf}}}+R_f\frac{I_f}{I_{\mathrm{Saf}}}$

Equation 30

Here, at the pure fault current I of relay mounting points _SafBe zero, the positive and negative phase-sequence current and, and utilize the electric current that flow to the trouble spot and positive phase sequence and negative phase sequence current distribution coefficient to represent so that obtain equation 31 and equation 32:

I _Saf＝I _S0+I _S1+I _S2

Equation 31, and

I _Saf＝(D _Sa0I _f0+D _Sa1I _f1+D _Sa2I _f2)＝(D _Sa0+2D _Sa1)I _f1

Equation 32

Obtain new current distribution factor by equation 31 and equation 32 by equation 33:

$D_{\mathrm{Sa}}=\frac{I_{\mathrm{<figure-callout\; id="1"\; label="Saf\; I\; f"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">Saf</figure-callout>}}}{I_f}=(D_{\mathrm{Sa}0}+2D_{\mathrm{Sa}1})=\frac{p{B}_{\mathrm{Sa}}+C_{\mathrm{Sa}}}{A_{\mathrm{Sa}}}$

Equation 33

Wherein

A _Sa＝A _Sa0A _Sa1，

B _Sa＝B _Sa0A _Sa1+2A _Sa0B _Sa1，and

C _Sa＝C _Sa0A _Sa1+2A _Sa0C _Sa1.

Simultaneously, equation 3,5 and 33 equations are used to derive from equation 34,35 equations and equation 36:

$\frac{I_{S0}}{I_{\mathrm{Saf}}}=\frac{A_{\mathrm{Sa}}}{A_{\mathrm{Sa}0}}\frac{p{B}_{\mathrm{Sa}0}+C_{\mathrm{Sa}0}}{p{B}_{\mathrm{Sa}}+C_{\mathrm{Sa}}}$

Equation 34

$\frac{I_{T0}}{I_{\mathrm{Saf}}}=\frac{A_{\mathrm{Sa}}}{A_{\mathrm{Sc}0}}\frac{p{B}_{\mathrm{Sc}0}+C_{\mathrm{Sc}0}}{p{B}_{\mathrm{Sa}}+C_{\mathrm{Sa}}}$

Equation 35

$\frac{I_f}{I_{\mathrm{Saf}}}=\frac{3A_{\mathrm{Sa}}}{p{B}_{\mathrm{Sa}}+C_{\mathrm{Sa}}}$

Equation 36

With equation 34,35 equations and equation 36 substitution equations 30 and about fault distance p arrangement, so that obtain equation 37 as quadratic equation about fault distance p:

(x ₁+jy ₁)p ²+(x ₂+jy ₂)p+(x ₃+jy ₃)+(x ₄+jy ₄)R _f＝0

Equation 37

Wherein

$x_1+\mathrm{<figure-callout\; id="1"\; label="j\; y"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">j</figure-callout>}{y}_{}{}_1=Z_{L1}(1+\frac{I_{\mathrm{Sal}}}{I_{\mathrm{Saf}}})B_{\mathrm{Sa}}+(Z_{L0}-Z_{L1})\frac{A_{\mathrm{Sa}}}{A_{\mathrm{Sa}0}}{B}_{\mathrm{Sa}0}+Z_m\frac{A_{\mathrm{Sa}}}{A_{\mathrm{Sc}0}}{B}_{\mathrm{Sc}0}$

$x_2+j{y}_2=Z_{L1}(1+\frac{I_{\mathrm{SaL}}}{I_{\mathrm{Saf}}})C_{\mathrm{Sa}}+(Z_{L0}-Z_{L1})\frac{A_{\mathrm{Sa}}}{A_{\mathrm{Sa}0}}{C}_{\mathrm{Sa}0}+Z_m\frac{A_{\mathrm{Sa}}}{A_{\mathrm{Sc}0}}{C}_{\mathrm{Sc}0}$

$-\frac{V_{\mathrm{Sa}}}{I_{\mathrm{Saf}}}{B}_{\mathrm{Sa}}$

$x_3+y_3=-\frac{V_{\mathrm{Sa}}}{I_{\mathrm{Saf}}}{C}_{\mathrm{Sa}}$

x ₄+y ₄＝3A _Sa

After equation 37 is divided into real part and imaginary part, cancellation fault resstance R _fSo that obtain equation 38:

x ₁p ²+x ₂p+x ₃+x ₄R _f＝0

y ₁p ²+ y ₂P+y ₃+ y ₄R _f=0＞... equation 38

Wherein, the quadratic expression by the quadratic equation (equation 39) that utilizes obtains fault distance p:

$(x_1-y_1\frac{x_4}{y_4})p^2+(x_2-y_2\frac{x_4}{y_4})p+(x_3-y_3\frac{x_4}{y_4})=0$

Equation 39

Fig. 9 is used to represent according on the double electricity transmission line of the present invention or the circuit diagram of the system of three power transmission lines when being short-circuited.

Here, correct localization of fault during for line-to-ground fault of generation or short-circuit between conductors and two line-to-ground faults on parallel double electricity transmission line, the fault resstance of consideration in the trouble spot develops this equation, and by mode from the relational expression cancellation fault resstance identical, so that eliminate the influence of fault resstance with earth fault.

Therefore, according to disclosed fault location algorithm in Fig. 5 B and the voltage equation after disclosed short-circuit between conductors faulty circuit obtains fault in Fig. 8, promptly equation 40 at step S322:

V _Sab＝V _Sa-V _Sb

＝V _Saf-V _Sbf+V _SaL-V _SbL+V _fa-V _fb

＝(V _S0+V _S1+V _S2)-(V _S0+a ²V _S1+aV _S2)+V _SaL-V _SbL

+(V _f0+V _f1+V _f2)-(V _f0+a ²V _f1+aV _f2)

＝(1-a ²)V _S1+(1-a)V _S2+V _SaL-V _SbL+(1-a ²)V _f1+(1-a)V _f2

Equation 40

Wherein,

V _Saf, V _SafBe a phase and the b phase voltage after the fault from the relay mounting points to the trouble spot,

V _SaL, V _SaLBe a phase and the b phase voltage before the fault from the relay mounting points to the trouble spot, and

V _Fa, V _FbBe a phase and the b phase voltage after the fault of trouble spot.

Then, at step S323, obtain from the symmetrical voltage of relay mounting points and trouble spot according to the voltage equation of releasing (equation 41):

V _S0＝pZ _L0I _S0，V _S1＝pZ _L1I _S1，V _S2＝pZ _L2I _S2

V _f0＝pR _fI _f0，V _f1＝R _fI _f1，V _f2＝R _fI _f2

Equation 41

At step S324, if symmetrical voltage is updated to voltage equation, or with reference to equation 3, or zero-phase-sequence current distribution coefficient equation, equation 8 or positive-phase-sequence current distribution coefficient equation and equation 9 or negative phase sequence current distribution coefficient equation, obtain following mutual relationship:

I _f0＝I _S0/D _Sa0，I _f1＝I _S1/D _Sa1，I _f2＝I _S2/D _Sa2

If these current distribution factors are updated to equation 40 and arrangement, utilize equation 42 to obtain voltage V _Sab:

$V_{\mathrm{Sab}}=p{Z}_{L1}(I_{\mathrm{Sa}}-I_{\mathrm{Sb}})+R_f-\frac{(I_{\mathrm{Saf}}-I_{\mathrm{Sbf}})}{{\mathrm{<figure-callout\; id="1"\; label="D\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">D</figure-callout>}}_{\mathrm{Sa}}}$

Equation 42

At step S325 and step S326, if with positive-phase-sequence current distribution coefficient D _Sa1Be updated to equation 42 and arrangement, utilize equation 43 to obtain voltage V _Sab:

$V_{\mathrm{Sab}}=p{Z}_{L1}(I_{\mathrm{Sa}}-I_{\mathrm{Sb}})+\frac{R_f{A}_{\mathrm{Sa}1}(I_{\mathrm{Saf}}-I_{\mathrm{Sbf}})}{\mathrm{<figure-callout\; id="1"\; label="p\; B\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">p</figure-callout>}{B}_{\mathrm{Sa}}{1}_{}+{\mathrm{<figure-callout\; id="1"\; label="C\; Sa"\; filenames="C0112573800322.png,C0112573800333.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{Sa}}}$

Equation 43

At step S327, put above-mentioned numerical value in order about fault distance p, obtain equation 44:

(m ₁+jn ₁)p ²+(m ₂+jn ₂)p+(m ₃+jn ₃)+(m ₄+jn ₄)R _f＝0

Equation 44

Wherein,

m ₁+jn ₁＝Z _L1(I _Sa-I _Sb)B _Sa1，

m ₂+jn ₂＝Z _L1(I _Sa-I _Sb)C _Sa1-V _SabB _Sa1，

m ₃+jn ₃＝-V _SabC _Sa1，and

m ₄+jn ₄＝(I _Saf-I _Sbf)A _Sa1.

At step S328, if equation 44 is divided into real part and imaginary part, and at step S329 and step S330 cancellation fault resstance R _f, step S331 in equation 45 and equation 46 as can be seen, can obtain fault distance p from the quadratic expression of quadratic equation:

m ₁p ²+m ₂p+m ₃+m ₄R _f＝0

n ₁p ²+n ₂p+n ₃+n ₄R _f＝0

Equation 45, and

$(m_1-n_1\frac{m_4}{n_4})p^2+(m_2-n_2\frac{m_4}{n_4})p+(m_3-n_3\frac{m_4}{n_4})=0$

Equation 46

Figure 10 be used to illustrate according to of the present invention when two power transmission line ground short circuits and three-phase shortcircuit take place in the parallel double electricity transmission line run duration circuit diagram of Fault Locating Method.

Obtain equation 47 from two power transmission line ground fault circuits shown in Fig. 9 as voltage equation:

V _Sa-V _Sb＝V _Saf-V _Sbf+V _SaL-V _SbL+V _fa-V _fb+V _ma-V _mb

Equation 47

Wherein,

V _Ma, V _MbBe the zero phase sequence voltage of non-fault line,

V _FaBe a phase voltage from the trouble spot to ground, and

V _FbIt is the b phase voltage from the trouble spot to ground.

Because the zero phase sequence voltage V of non-fault line _Ma=V _Mb, equation 47 can utilize equation 48 to express:

V _Sa-V _Sb＝V _Saf-V _Sbf+V _SaL-V _SbL+V _fa-V _fb

Equation 48

Here, as by equation 48 and equation 40 as can be seen, the voltage equation in the relay mounting points during double ground fault has the form identical with short-circuit between conductors, can obtain fault distance p by the differentiation identical with the localization of fault of online short circuit.

According to the present invention as by discussed above, when on power transmission line, breaking down, may be calculated the spendable fault electricity electric current of zero-phase-sequence current and the current distribution factor of prediction non-fault line, therefore the zero-phase-sequence current of this non-fault line is that correct fault location is needed, and can correctly locate correct distance from the relay mounting points to the trouble spot by this current distribution factor.The influence that Fault Locating Method of the present invention is not changed by the source impedance of background system.In addition, by develop relational expression cancellation fault resstance according to fault location algorithm, therefore the influence of a feasible resistance of can fixing a breakdown fully can calculate correct fault distance.

Though introduced the present invention with reference to preferred embodiments more of the present invention, those skilled in the art will appreciate that, can carry out various improvement and variation under the situation that does not break away from the design of the present invention that limited by the claim that is proposed and scope.

Claims (9)

1. parallel double electricity transmission line Fault Locating Method, the step that comprises has:

Three-phase voltage on the power transmission line and current signal numerical value are converted to small-signal;

Compile and store through the conversion voltage and current numerical value as data;

Stored voltage and current data and the reference data that sets in advance are compared, to judge fault and the fault type on the power transmission line;

If in response on the comparison step power transmission line fault being arranged, then separate and obtain after the fault and preceding voltage and current data;

Carry out fault location algorithm according to the originate mode that pre-sets according to the data of obtaining, obtaining current distribution factor, and by utilizing current distribution factor to calculate the failure message of fault distance and trouble spot; And

Fault distance that storage is calculated and information and the fault distance and the information of storing to the outside transmission,

Wherein, in described separation and obtaining step, use and separate and obtain voltage and current data before the transmission line fault in 30 cycles and the voltage and current data after the fault in 60 cycles.

2. parallel double electricity transmission line Fault Locating Method according to claim 1, wherein, utilize symmetrical coordinates that current distribution factor is decomposed into zero, positive and negative phase-sequence current distribution coefficient, so that in each balancing circuitry, handle and in fault location algorithm, use this voltage and current, so that according to parallel double electricity transmission line fault type fault location point.

3. parallel double electricity transmission line Fault Locating Method according to claim 1 is carried out fault location algorithm in the time of can also working as from protective relay input fault generation information.

4. parallel double electricity transmission line Fault Locating Method according to claim 1 is wherein carried out fault location algorithm by differentiating according to the transmission line fault type, and under the situation of a line-to-ground fault, carries out following steps:

Set up electric current in voltage equation and the cancellation non-fault line and the other end by data after the fault, so that calculate the zero-phase-sequence current distribution coefficient;

By utilizing zero-phase-sequence current and the zero-phase-sequence current distribution coefficient that is calculated, be based upon the voltage equation of relay mounting points;

Voltage equation that the current distribution factor substitution has been set up and arrangement are divided into real part and imaginary part about the relational expression of fault distance; And

Cancellation steadying resistance from the relational expression of the fault distance that is divided into real part and imaginary part, and with this relation table arrangement for about the quadratic equation of fault distance so that calculate fault distance.

5. parallel double electricity transmission line Fault Locating Method according to claim 1 is wherein carried out fault location algorithm by differentiating according to fault type, and under the situation of a line-to-ground fault, carries out following steps:

Set up electric current in voltage equation and the cancellation non-fault line and the other end by data after the fault, to calculate the positive-phase-sequence current distribution coefficient;

By utilizing positive-phase-sequence current and the positive-phase-sequence current distribution coefficient that is calculated, be based upon the voltage equation of relay mounting points;

Voltage equation that the current distribution factor substitution has been set up and arrangement are divided into real part and imaginary part about the relational expression of fault distance; And

The cancellation fault resstance, and will put in order and be the quadratic equation about fault distance, to calculate fault distance.

6. parallel double electricity transmission line Fault Locating Method according to claim 5 is wherein by utilizing the quadratic expression in the quadratic equation to calculate fault distance.

7. parallel double electricity transmission line Fault Locating Method according to claim 1 is wherein by utilizing newton La Fusen iterative computation to calculate fault distance.

8. parallel double electricity transmission line Fault Locating Method according to claim 1 is wherein carried out fault location algorithm by differentiating according to fault type, and under the situation of two line-to-ground faults and short circuit, carries out following steps:

Set up voltage equation and the symmetrical voltage that calculates in relay mounting points and trouble spot by data after the fault;

The voltage equation that this symmetrical voltage substitution has been set up is so that calculate the positive-phase-sequence current distribution coefficient;

The positive-phase-sequence current distribution coefficient that substitution is calculated, arrangement is divided into real part and imaginary part about the relational expression of fault distance; And

Cancellation fault resstance from the relational expression that separates, and will concern expression arrangement for about the quadratic equation of fault distance to calculate fault distance.

9. parallel double electricity transmission line fault locator comprises:

Be used for three-phase voltage on the power transmission line and current signal numerical value are converted to the parts of small-signal;

Be used to compile and store through the voltage and current numerical value of conversion parts as data;

Be used for stored voltage and current data and the reference data that sets in advance are compared, to judge the fault on the power transmission line and the parts of fault type;

If be used for fault being arranged, separate and obtain after the fault and the parts of preceding voltage and current data in response on this comparison power transmission line;

Be used for carrying out fault location algorithm according to the data of obtaining, obtaining current distribution factor, and be used for by utilizing current distribution factor to calculate the parts of the failure message of fault distance and trouble spot according to the originate mode that pre-sets; And

Be used for the fault distance of storage computation and information and send the fault distance of storage and the parts of information to the outside,

Wherein said compiling with memory unit comprises:

Signal conditioning unit is used to regulate three-phase voltage and current signal on the parallel double electricity transmission line;

Low-pass filter is used for from removing high fdrequency component through the voltage and current signal of regulating;

The A/D converting unit, the voltage and current conversion of signals that is used for having removed high fdrequency component is a digital signal, and

Storage unit is used to store this digital voltage and current data.

Images