CN101067641A - Single-ended fault location method of line against the influence of distributed capacitive current and transition resistance - Google Patents

The invention belongs to the electrical power system domain, specially relates to the line single end fault distance measuring method of the anti- distributed capacity electric current and the transition resistance influence. Including: surveys the transformer substation protection installment place fault phase voltage, the phase current, the zero sequence voltage, the zero sequence electric current and the negative sequence electric current as the input value; using the fault voltage cross zero time to measure the resistance characteristic which is not influence by transition resistance, from the protected line begin end start, computing the measure voltage real part computed value of the fault point voltage cross zero point time, compared with the measured value of the measure voltage real part, computing the error; and taking the delta-S as the step size, in turn computing the setting range which is protected by the send tripping signal, if cannot obtain the protect tripping signal, searching the total track length which is protected, taking the minimum point as the fault point. The invention method is not influenced by the distributed capacity electric current and transition resistance, does not have the false root problem of solving equation method and non convergence question of the iterative method, and has the very high practical value.

The line one-end fault ranging method of anti-capacitance current and transition resistance influence

Technical field

The invention belongs to field of power, the line one-end fault ranging method of particularly a kind of anti-capacitance current and transition resistance influence.

Background technology

Transmission line of electricity is being undertaken the vital task that transmits electric energy, and its fault directly threatens the safe operation of electric system.Especially, the electric pressure of China develops to extra-high voltage (is representative with 1000kV) from UHV (ultra-high voltage) (is representative with 500kV), the transmission line of electricity capacity further increases, fault localization is got rid of line fault and is restored electricity as early as possible for quickening accurately, thereby the stability, the stable operation of assurance security of system that improve electric system have great importance.

Fault distance-finding method is divided into two kinds: single-ended method and both-end method from using the angle of electric parameters.The both-end method need be used the electric information at circuit two ends, can realize accurate localization of fault on the principle, but in actual applications, still is subjected to the influence of two ends sample frequency difference or phase deviation.Single-ended method does not need extra equipment, only adopts local electric parameters to carry out fault localization, is not subjected to the restriction of mechanics of communication, is the focus that industry is paid close attention to always.

The one-end fault ranging algorithm is divided into two classes from the angle of principle: impedance method and traveling wave method.Traveling wave method is realized fault localization by the time of measuring row wave-wave head commute between observation station and trouble spot, but the single-ended traveling wave method can not effectively be discerned the reflected traveling wave that comes from the trouble spot and come from the reflected traveling wave of other wave impedance discontinuous point, so the single-ended traveling wave method does not obtain the essence application.Impedance method: calculate observation station to the line impedance value between the trouble spot according to voltage, galvanometer after the fault, lead owing to ignored distributed capacitance, the electricity of transmission line of electricity, the proportional example relation of line impedance value and fault distance, thus realize localization of fault; But the single-ended impedance method can not be eliminated the influence of fault transition resistance and offside system impedance fully, precision is relatively poor than the both-end method, a lot of scholars are at this problem, proposed abundant the improving one's methods of kind, mainly contained: power frequency impedance method (1), separated Differential Equation Algorithm (2), zero-sequence current phase place revised law (3), fault current phase place revised law (4), separate quadratic equation method (5) etc.Method (1), (2) are assumed fault point electric current and observation station electric current same-phase all, method (3), (4), (5) all need known offside system impedance value, accurate localization of fault, yet system operation mode is changeable, be difficult to accurately obtain the peer-to-peer system resistance value, so the fault localization precision is not very high.But single-ended impedance fault localization algorithm does not need the information of offside, and is low to hardware requirement, is easy to realize; Though distance accuracy is not high, algorithm stability is fine, so has obtained at the scene using widely.The microcomputer protecting device of middle operation all adopts the single-ended impedance method as its fault localization element basically at the scene at present; utilize the stability of impedance method range finding simultaneously; the comprehensive combined method range finding of using single-ended impedance method and traveling wave method has also greatly promoted the performance that single-ended traveling wave is found range.

The single-ended impedance fault distance-finding method is widely used on high pressure (is representative with 220kV), supertension line, and its prerequisite is to think to measure impedance and the proportional example relation of fault distance that promptly the distributed capacitance of circuit can be ignored.This is because high pressure, supertension line length are generally less than 400km, and it is little to ignore the error that the influence of distributed capacitance brings, and can satisfy the requirement of rig-site utilization.And for the ultra-high/extra-high voltage long transmission line of the above electric pressure of 750kV, the electric current of the capacitance current of circuit and circuit transmission natural power is compared and can be reached more than 76%, and the error of still ignore distributed capacitance this moment, bringing with lumpy line Model Calculation fault distance can not be accepted by the scene.

Summary of the invention

The objective of the invention is for overcoming the weak point of prior art, propose a kind of new anti-capacitance current and the line one-end fault ranging method of transition resistance influence, the physical model of this method adopts the distribution parameter modeling, is not subjected to the influence of capacitance current; This method utilizes fault point voltage zero crossing data computation constantly to measure resistance value, is not subjected to the influence of transition resistance; This method is a kind of method of search type, does not have the pseudo-root problem of the method for solving equation and the not convergence problem of process of iteration, has very high practical value.

The line one-end fault ranging method of a kind of anti-capacitance current that the present invention proposes and transition resistance influence may further comprise the steps:

Wherein  is that fault is separate: A phase, B phase or C phase;

3) calculate the fault point voltage zero crossing constantly, the real part measured value of protection installation place measuring voltage is:

4) fault distance is taken as initial value l _Fault, calculate the protection installation place and measure electric current:

P = Z c 0 Z c 1 ( T · ch γ · 1 l fault + sh γ · 0 l fault - T · ch γ · 0 l fault sh γ · 1 l fault ) - 1

P is the zero sequence current compensation factor based on the circuit distribution parameter, wherein:

5) according to Transmission Line Distributed Parameter computational scheme resistance value Z _FaultFor:

Z fault = Z c 1 th γ · 1 l fault = Z relay ( cos ( ωt + τ ) + j sin ( ωt + τ ) )

Wherein: Z _RelayBe the line impedance amplitude, τ is the line impedance angle;

6) according to the fault point voltage zero crossing constantly, the real part calculated value of protection installation place measurement electric current and line impedance value calculating measuring voltage is:

U _{mea_cal}＝I _relayZ _relaycos(90°-α+τ+β)

7) calculating the real part calculated value of measuring voltage and the error of measured value is:

Error＝|U _{mea_cal}-U _{mea_meter}|

8) fault distance initial value l _FaultS increases one by one with step delta, return step 4), calculate the error amount of every bit successively, (setting range is according to the route protection of the relay protection national standard principle value of adjusting until the setting range of the protection of sending out trip signal, for example I section ground distance protection is sent out trip signal, and its setting range is 80% of a protected circuit total length; Total track length is 800km; then search procedure is that step-length increases to 640km one by one with Δ S), if can't be protected trip signal, then search for the protected circuit total length; the point of getting the error minimum is the trouble spot, and this distance to the route protection installation place is a fault distance.

Characteristics of the present invention and technique effect:

The inventive method is based on the proposition of Transmission Line Distributed Parameter model, can accurately describe the physical characteristics of transmission line of electricity, has the ability of natural anti-capacitance current influence; The inventive method is utilized fault point voltage zero crossing data computation fault distance constantly, is not subjected to the influence of transition resistance; The inventive method is a kind of method of search type, does not have the pseudo-root problem of the method for solving equation and the not convergence problem of process of iteration, has very high practical value.The inventive method is applicable to the transmission line of electricity of any electric pressure, especially for 750kV and above ultra-high/extra-high voltage transmission of electricity long transmission line, the fault localization precision of application the inventive method significantly improves than other one-end fault ranging method, can satisfy on-the-spot requirement.

Description of drawings

Fig. 1 is for using the system for ultra-high voltage transmission synoptic diagram of the inventive method.

Fig. 2 compares based on the fault localization error characteristics of application of model the inventive method shown in Figure 1 and traditional power frequency impedance method fault localization error characteristics; Wherein:

(a) for using traditional power frequency impedance method fault localization error characteristics;

(b) for using the fault localization error characteristics of the inventive method;

Embodiment

The line one-end fault ranging method embodiment of anti-capacitance current that the present invention proposes and transition resistance influence is described in detail as follows:

Use a kind of 1000kV system for ultra-high voltage transmission type of the present invention as shown in Figure 1, system is a typical both end power supplying system, and two side bus are respectively M and N, and line length is 800km, and the line parameter circuit value value is as shown in table 1.Both sides system impedance parameter is as follows, and N side power supply angle falls behind M side 44 degree, and M side and N side electromotive force are respectively 1.1062 and 1.1069 times of rated voltages.The fault location device of using the inventive method is installed in the M side, and voltage, electric current are respectively from line side voltage transformer (VT) (PT), current transformer (CT), and the positive dirction of electric current is electric current is flowed to circuit by bus a direction.

Both sides system impedance parameter is:

M side positive sequence system impedance: Z _M1=4.2643+j85.14528 Ω

M side zero sequence system impedance: Z _M0=98.533+j260.79 Ω

N side positive sequence system impedance: Z _N1=7.9956+j159.6474 Ω

N side zero sequence system impedance: Z _N0=184.749+j488.981 Ω

The line one-end fault ranging method that the present invention proposes is applicable to the range finding element and the fault location device independently of fault localization module, the fault oscillograph of any route protection.Present embodiment is an example with the fault localization module of using route protection of the present invention; with ground distance protection I section troubles inside the sample space is evaluating objects; protection domain adjust be 80% of total track length, emulation fault be the A of 420km place through 105 ohm of earth faults, the embodiment concrete steps are as follows:

1) measuring circuit is in transforming plant protecting installation place fault phase voltage phasor, phase current phasor, residual voltage phasor, zero-sequence current phasor, negative-sequence current phasor, and as input quantity, the present embodiment fault is the A phase mutually:

2) the initial phase angle α of computational scheme protection installation place negative-sequence current is:

3) protection installation place measuring voltage is:

Then calculate the fault point voltage zero crossing constantly, the real part measured value of protection measuring voltage is:

U _{mea_meter}＝U _relaycos(90°-α+θ)＝0.566cos(-21.53°+168.76°)＝-0.476MV

4) fault distance is taken as initial value l _Fault=1km, calculate and protect installation place measurement electric current to be:

Bring the aforementioned calculation result into P value computing formula, ask for the P value and be:

P = Z c 0 Z c 1 ( T · ch γ · 1 l fault + sh γ · 0 l fault - T · ch γ · 0 l fault sh γ · 1 l fault ) - 1 = 1.901 - j · 0.700

Therefore, obtain measuring electric current:

5) according to Transmission Line Distributed Parameter computational scheme resistance value Z _FaultFor:

Z fault = Z c 1 th γ · 1 l fault = Z relay ( cos ( ωt + τ ) + j sin ( ωt + τ ) )

6, constantly, the real part calculated value of protection installation place measurement electric current and line impedance value calculating measuring voltage is according to the fault point voltage zero crossing:

U _{mea_cal}＝I _relayZ _relaycos(90°-α+τ+β)

＝4.182×0.259×cos(-21.53°+116.87°+88.209°)＝-0.0011MV

7) calculating the real part calculated value of measuring voltage and the error of measured value is:

Error＝|U _{mea_cal}-U _{mea_meter}|＝|-0.0011+0.476|＝0.4749MV

8) fault distance initial value l _Fault1km increases one by one with step-length, returns step 4, calculates the error amount of every bit successively, and until the setting range 640km of I section ground distance protection, then error amount is as shown in table 2:

The point of error minimum is the 426km place, therefore thinks that the trouble spot is positioned at 426km.Calculating the fault localization relative error is:

426 - 420 800 × 100 % = 0.75 %

Use the inventive method and the fault localization error characteristics of using traditional power frequency impedance method for comparing check, the present invention is based on model shown in Figure 1 and carried out a large amount of Digital Simulations, the trouble spot is selected to be decremented to 10km gradually from 600km, and step-length is 10km; The fault transition resistance is since 5 ohm, with 50 ohm be step-length, increase to 155 ohm gradually.Simulation result as shown in Figure 2.

By Fig. 2 (a) as seen, the fault localization error characteristics of using traditional power frequency impedance method are very poor, even under the less situation of transition resistance (5 ohm, 55 ohm), the fault localization maximum relative error also can reach 30%; Along with the further increase of transition resistance value, the fault localization relative error reaches more than 50%, and the range finding result does not have credibility.

The fault localization error characteristics that adopt the inventive method are shown in Fig. 2 (b), and under the situation of little transition resistance, the fault localization maximum relative error is no more than 0.75%, realize precision ranging; Under the situation of great transition resistance, the precision of fault localization descends to some extent, but maximum relative error can satisfy the requirement of rig-site utilization less than 1.5%.

1、一种抗分布电容电流和过渡电阻影响的线路单端故障测距方法，包括以下步骤：1. A line single-ended fault location method for resisting the influence of distributed capacitive current and transition resistance, comprising the following steps: 1)测量线路在变电站保护安装处故障相电压相量

故障相电流相量

零序电压相量 零序电流相量

负序电流相量

作为输入量；其中为故障相别：A相、B相或C相；1) Measure the fault phase voltage phasor of the line at the protection installation of the substation

Fault phase current phasor

zero sequence voltage phasor zero sequence current phasor

negative sequence current phasor

As an input; where  is the fault phase: A phase, B phase or C phase; 2)计算故障点电压过零点时刻为：

其中α为线路保护安装处负序电流的初始相角，ω为电力系统额定角频率值；2) Calculate the zero-crossing time of the fault point voltage as:

Where α is the initial phase angle of the negative-sequence current where the line protection is installed, and ω is the rated angular frequency value of the power system; 3)计算故障点电压过零点时刻，保护安装处测量电压的实部实测值为：3) Calculate the time when the voltage at the fault point crosses zero, and the measured value of the real part of the measured voltage at the protection installation is: 测量电压 其中：U_relay为测量电压幅值，θ为测量电压初始相角；故障点电压过零点时刻，测量电压的实部实测值为：U_{mea_meter}＝U_relaycos(90°-α+θ)Measuring voltage Among them: U _relay is the measured voltage amplitude, θ is the initial phase angle of the measured voltage; when the voltage at the fault point crosses zero, the measured value of the real part of the measured voltage is: U _{mea_meter} = U _relay cos(90°-α+θ) 4)故障距离取为初始值l_fault，计算保护安装处测量电流：4) The fault distance is taken as the initial value l _fault , and the measured current at the protection installation is calculated: 测量电流 其中：I_relay为测量电流幅值，β为测量电流初始相角；measuring current Where: I _relay is the measured current amplitude, β is the initial phase angle of the measured current; PP == ZZ cc 00 ZZ cc 11 (( TT ·· chch γγ ·&Center Dot; 11 ll faultfault ++ shsh γγ ·· 00 ll faultfault -- TT ·· chch γγ ·&Center Dot; 00 ll faultfault shsh γγ ·&Center Dot; 11 ll faultfault )) -- 11 P为基于线路分布参数的零序电流补偿系数，其中：P is the zero-sequence current compensation coefficient based on line distribution parameters, where: Z_c1为正序波阻抗： Z c 1 = ( R 1 + jω L 1 ) / ( G 1 + jω C 1 ) , R₁、L₁、G₁、C₁分别为单位长度线路的正序电阻、电感、电导和电容值；Z _c1 is the positive sequence wave impedance: Z c 1 = ( R 1 + jω L 1 ) / ( G 1 + jω C 1 ) , R ₁ , L ₁ , G ₁ , and C ₁ are the positive sequence resistance, inductance, conductance, and capacitance of the line per unit length, respectively; Z_c0为零序波阻抗： Z c 0 = ( R 0 + jω L 0 ) / ( G 0 + jω C 0 ) , R₀、L₀、G₀、C₀分别为单位长度线路的零序电阻、电感、电导和电容值；Z _c0 is the zero-sequence wave impedance: Z c 0 = ( R 0 + jω L 0 ) / ( G 0 + jω C 0 ) , R ₀ , L ₀ , G ₀ , and C ₀ are the zero-sequence resistance, inductance, conductance, and capacitance of the line per unit length, respectively;

为正序传播系数： γ · 1 = ( R 1 + j ωL 1 ) ( G 1 + j ωC 1 ) ;

is the positive sequence propagation coefficient: γ &Center Dot; 1 = ( R 1 + j ωL 1 ) ( G 1 + j ω C 1 ) ;

为零序传播系数： γ · 0 = ( R 0 + j ωL 0 ) ( G 0 + j ωC 0 ) ;

is the zero-sequence propagation coefficient: γ · 0 = ( R 0 + j ω L 0 ) ( G 0 + j ω C 0 ) ; T为基于分布参数模型的系统等值零序阻抗： T = U · 0 Z c 0 I · 0 ; T is the equivalent zero-sequence impedance of the system based on the distributed parameter model: T = u &Center Dot; 0 Z c 0 I · 0 ; 5)根据输电线路分布参数计算线路阻抗值Z_fault为：5) Calculate the line impedance value Z _fault according to the transmission line distribution parameters as: ZZ faultfault == ZZ cc 11 ththe th γγ ·&Center Dot; 11 ll faultfault == ZZ relayrelay (( coscos (( ωtωt ++ ττ )) ++ jj sinsin (( ωtωt ++ ττ )) )) 其中：Z_relay为线路阻抗幅值，τ为线路阻抗角；Among them: Z _relay is the line impedance amplitude, τ is the line impedance angle; 6)根据故障点电压过零点时刻，保护安装处测量电流和线路阻抗值计算测量电压的实部计算值为：6) Calculate the real part of the measured voltage according to the zero-crossing moment of the fault point voltage, the measured current at the protection installation and the line impedance value: U_{mea_cal}＝I_relayZ_relaycos(90°-α+τ+β)U _{mea_cal} ＝I _relay Z _relay cos(90°-α+τ+β) 7)计算测量电压的实部计算值与实测值的误差为：7) Calculate the error between the calculated value of the real part of the measured voltage and the measured value: Error＝|U_{mea_cal}-U_{mea_meter}|Error＝|U _{mea_cal} -U _{mea_meter} | 8)故障距离初始值l_fault以步长ΔS逐次增加，返回步骤4)，依次计算每一点的误差值，直至发跳闸信号的保护的整定范围，如果无法得到保护跳闸信号，则搜索被保护线路全长，取误差最小的点为故障点，该点至线路保护安装处的距离为故障距离。8) The initial value of the fault distance l _fault is gradually increased with the step size ΔS, return to step 4), and calculate the error value of each point in turn until the setting range of the protection that sends the trip signal. If the protection trip signal cannot be obtained, search for the protected line The overall length, the point with the smallest error is taken as the fault point, and the distance from this point to the line protection installation is the fault distance.