CN103107524A

CN103107524A - Electric transmission line phase fault relay protection method

Info

Publication number: CN103107524A
Application number: CN2013100429578A
Authority: CN
Inventors: 林富洪; 曾惠敏
Original assignee: State Grid Corp of China SGCC; State Grid Fujian Electric Power Co Ltd; Maintenance Branch of State Grid Fujian Electric Power Co Ltd; Putian Power Supply Co of State Grid Fujian Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; State Grid Fujian Electric Power Co Ltd; Maintenance Branch of State Grid Fujian Electric Power Co Ltd; Putian Power Supply Co of State Grid Fujian Electric Power Co Ltd
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2013-05-15
Anticipated expiration: 2033-01-31
Also published as: CN103107524B

Abstract

The invention discloses a relay protection method for phase-to-phase faults of transmission lines. The method of the invention is used as a measuring element for measuring impedance of the distance protection of short-circuit faults between phases of transmission lines, and can accurately measure the short-circuit fault point between phases to the protection installation place under any fault condition. The measured impedance has nothing to do with the phase-to-phase fault point voltage, load current and transition resistance. The method of the present invention can be reliably blocked under the condition of heavy load of the transmission line, and the method of the present invention can reliably and correctly operate when a high-impedance short-circuit fault between phases occurs on the line under the condition of heavy-load transmission. , to meet the requirements of relay protection selectivity, reliability, sensitivity and quick action.

Description

A method for relay protection of transmission line phase-to-phase fault

技术领域 technical field

本发明涉及电力系统继电保护技术领域，特别是一种输电线路相间故障继电保护方法。The invention relates to the technical field of relay protection of power systems, in particular to a relay protection method for phase-to-phase faults of transmission lines.

背景技术 Background technique

工频变化量距离保护通过反应工作电压幅值突变量构成距离保护，该方法具有受电力系统运行方式影响小和抗过渡电阻能力强等优势。但由于该方法所采用的工作电压幅值突变量仅在故障初期存在，无法用作超/特高压交流输电线路后备保护。The power frequency variation distance protection constitutes the distance protection by reflecting the sudden change of the working voltage amplitude. This method has the advantages of being less affected by the operation mode of the power system and having a strong ability to resist transition resistance. However, since the mutation of the working voltage amplitude used in this method only exists in the initial stage of the fault, it cannot be used as a backup protection for EHV/UHV AC transmission lines.

阻抗距离保护根据测量阻抗大小反映故障距离长度以区分故障点位于保护区内还是位于保护区外。阻抗距离保护由于受电力系统运行方式和结构变化影响小，用于计算测量阻抗的电气量为全故障分量，适用于整个故障过程的输电线路保护。因此，阻抗距离保护既可用于高压输电线路主保护，也可用作超/特高压交流输电线路后备保护。Impedance distance protection reflects the fault distance according to the measured impedance to distinguish whether the fault point is inside or outside the protection zone. Impedance distance protection is less affected by power system operation mode and structural changes, and the electrical quantity used to calculate and measure impedance is the full fault component, which is suitable for transmission line protection during the entire fault process. Therefore, the impedance distance protection can be used not only for the main protection of high-voltage transmission lines, but also for the backup protection of EHV/UHV AC transmission lines.

传统相间阻抗距离保护假设相间故障点电压为零，通过相间故障电压和相间故障电流的比值计算测量阻抗，并根据测量阻抗大小来反映故障点的远近以决定是否发出跳闸信号。实际上，在电力系统中，除了人为构造的金属性相间短路故障外，相间故障点电压几乎不可能为零。因此，相间故障点电压会对相间距离保护动作性能造成严重的影响。The traditional phase-to-phase impedance distance protection assumes that the phase-to-phase fault point voltage is zero, calculates the measured impedance by the ratio of the phase-to-phase fault voltage to the phase-to-phase fault current, and reflects the distance of the fault point according to the measured impedance to determine whether to send a trip signal. In fact, in the power system, except for the artificially constructed metallic phase-to-phase short-circuit fault, the voltage at the phase-to-phase fault point is almost impossible to be zero. Therefore, the phase-to-phase fault point voltage will have a serious impact on the performance of the phase-to-phase distance protection.

实际电力系统中，由过渡电阻所带来附加阻抗会严重影响阻抗距离保护的动作性能。若过渡电阻产生的附加阻抗呈阻感性容易造成保护区内相间短路故障时相间阻抗距离保护拒动；若过渡电阻产生的附加阻抗呈阻容性容易造成保护区外相间短路故障时相间阻抗距离保护动作产生超越。高/超/特压交流输电线路往往也是重负荷输电线路，重负荷电流会使阻抗距离保护误动，重负荷电流对阻抗距离保护动作性能的影响不能忽略。In the actual power system, the additional impedance brought by the transition resistance will seriously affect the action performance of the impedance distance protection. If the additional impedance generated by the transition resistance is resistive and inductive, it is easy to cause the phase-to-phase impedance distance protection to refuse to operate when there is a short-circuit fault between phases in the protection zone; Action produces transcendence. High/super/extreme voltage AC transmission lines are often heavy-duty transmission lines. Heavy-load currents will cause impedance distance protection to malfunction, and the impact of heavy-load current on the performance of impedance distance protection cannot be ignored.

发明内容 Contents of the invention

本发明的目的在于克服已有技术存在的不足，提供一种输电线路相间故障继电保护方法。该方法可实现输电线路相间短路故障距离保护的测量阻抗的精确测量功能。The object of the present invention is to overcome the deficiencies of the prior art and provide a relay protection method for phase-to-phase faults of transmission lines. The method can realize the precise measurement function of the measured impedance of the phase-to-phase short-circuit fault distance protection of the transmission line.

一种输电线路相间故障继电保护方法，其步骤如下：A method for relay protection of transmission line phase-to-phase faults, the steps of which are as follows:

（1）测量输电线路保护安装处的故障相间电压

、故障相间电流

和正常相负序电流

；其φφ分别为AB相或BC相或CA相；Ψ分别对应为C相或A相或B相。(1) Measure the fault phase-to-phase voltage at the installation of transmission line protection

, fault current between phases

and normal phase negative sequence current

; Its φφ is AB phase or BC phase or CA phase respectively; Ψ corresponds to C phase or A phase or B phase respectively.

（2）计算相间短路故障点到输电线路保护安装处的测量阻抗Z_φφ,ce：(2) Calculate the measured impedance Z _φφ,ce from the phase-to-phase short-circuit fault point to the transmission line protection installation:

${Z Z}_{φφ φφ,, ce ce} = = (({x x}_{set set} - - | | \frac{{\overset{\cdot &Center Dot;}{U u}}_{φφ φφ} - - {x x}_{set set} {z z}_{11} {\overset{\cdot \cdot}{I I}}_{φφ φφ}}{{z z}_{11} {\overset{\cdot \cdot}{I I}}_{φφ φφ} sin sin ((β β + + γ γ))} | | sin sin α α)) {z z}_{11}$

其中，为故障相间电压；为故障相间电流；

为正常相负序电流；φφ分别为AB相或BC相或CA相；Ψ分别对应为C相或A相或B相；x_set为保护整定范围；β=Arg(z₁)；

；；z₁为单位长度输电线路正序阻抗；

表示正常相负序电流

经逆时针旋转90°后的电流相量。in, is the fault phase-to-phase voltage; is the fault current between phases;

is the normal phase negative sequence current; φφ is AB phase or BC phase or CA phase respectively; Ψ corresponds to C phase or A phase or B phase respectively; x _set is protection setting range; β=Arg(z ₁ );

; ; z ₁ is the positive sequence impedance of the transmission line per unit length;

Indicates the normal phase negative sequence current

Current phasor after rotating 90° counterclockwise.

本发明与现有技术相比较，具有以下积极成果：Compared with the prior art, the present invention has the following positive results:

本发明方法测量相间短路故障点到输电线路保护安装处的测量阻抗与相间故障点电压、过渡电阻和负荷电流无关，在输电线路重负荷情况下本发明方法可靠闭锁，在重负荷输电情况下线路发生相间高阻短路故障时本发明方法可靠正确动作。The method of the invention measures the measured impedance from the phase-to-phase short-circuit fault point to the protection installation of the transmission line and has nothing to do with the phase-to-phase fault point voltage, transition resistance and load current. The method of the invention can act reliably and correctly when a phase-to-phase high-resistance short-circuit fault occurs.

附图说明 Description of drawings

图1为应用本发明方法的输电线路相间短路故障示意图。Fig. 1 is a schematic diagram of a phase-to-phase short-circuit fault of a transmission line applying the method of the present invention.

图2为应用本发明方法的输电线路相间短路故障的

、

、、

、

和

的电气矢量关系图。Fig. 2 is the application of the transmission line phase-to-phase short-circuit fault of the inventive method

,

, ,

,

and

electrical vector diagram.

具体实施方式 Detailed ways

下面根据说明书附图对本发明的技术方案做进一步详细表述。The technical solution of the present invention will be further described in detail according to the accompanying drawings.

图1中PT为电压互感器、CT为电流互感器。保护装置对输电线路保护安装处的电压互感器PT的电压和电流互感器CT的电流波形进行采样得到电压、电流瞬时值。In Fig. 1, PT is a voltage transformer, and CT is a current transformer. The protection device samples the voltage of the voltage transformer PT and the current waveform of the current transformer CT at the place where the transmission line protection is installed to obtain instantaneous values of voltage and current.

通过傅里叶算法计算输电线路保护安装处的故障相间电压相量、故障相间电流相量

、正常相负序电流相量

，作为输入量；其中，φφ为故障相，分别为AB相或BC相或CA相；Ψ为正常相，分别对应为C相或A相或B相。Calculation of Fault Phase-to-Phase Voltage Phasor at Transmission Line Protection Installation by Fourier Algorithm , current phasor between fault phases

, Normal phase negative sequence current phasor

, as the input quantity; among them, φφ is the fault phase, which is AB phase or BC phase or CA phase respectively; Ψ is the normal phase, which corresponds to C phase, A phase or B phase respectively.

输电线路发生相间经过渡电阻R_f短路故障，相间故障点电压

、故障支路电流

，因为电阻性相间短路故障，在故障支路有

，从而

。When a short-circuit fault occurs between phases on the transmission line through the transition resistance _Rf , the voltage at the fault point between phases

, fault branch current

, because of the resistive phase-to-phase short-circuit fault, there is

,thereby

.

输电线路发生相间经过渡电阻短路故障，在故障支路有，从而

。其中，

、

分别为流经故障支路的正序电流、负序电流；

为正常相Ψ的故障点对地负序电流；

为经逆时针旋转90°后的电流相量。When a short-circuit fault occurs between phases of the transmission line through the transition resistance, there is a fault in the fault branch ,thereby

. in,

,

are the positive-sequence current and negative-sequence current flowing through the fault branch, respectively;

is the negative-sequence current of the fault point of the normal phase Ψ to ground;

for Current phasor after rotating 90° counterclockwise.

输电线路发生相间经过渡电阻短路故障，保护安装处测量到的正常相负序电流

与正常相故障点对地负序电流

同相位，即

。于是，得到。其中，

表示正常相负序电流经逆时针旋转90°后的电流相量。When a short-circuit fault occurs between phases of the transmission line through the transition resistance, the normal phase negative sequence current measured at the protection installation

Negative sequence current with normal phase fault point to ground

same phase, that is

. So, get . in,

Indicates the normal phase negative sequence current Current phasor after rotating 90° counterclockwise.

计算距保护安装处x_set位置的操作电压

：Calculate the operating voltage x _set from where the guard is installed

:

${\overset{\cdot \cdot}{U u}}_{φφ φφ,, set set} = = {\overset{\cdot \cdot}{U u}}_{φφ φφ} - - {x x}_{set set} {z z}_{11} {\overset{\cdot &Center Dot;}{I I}}_{φφ φφ} - - - - - - ((11))$

其中，z₁为单位长度输电线路正序阻抗。Among them, z ₁ is the positive sequence impedance of the unit length transmission line.

输电线路发生相间经过渡电阻短路故障的

、

、

、、

和

的电气矢量关系如图2所示。在图2中，由、

和

构成的矢量三角形里，根据三角形边角关系得到式（2）关系。The short-circuit fault between the phases through the transition resistance of the transmission line

,

, ,

and

The electrical vector relationship of is shown in Fig. 2. In Figure 2, by ,

and

In the formed vector triangle, the relationship of formula (2) is obtained according to the relationship between the sides and angles of the triangle.

${x x}_{s the s e e t t} ? ? x x = = | | \frac{{\overset{\cdot \cdot}{U u}}_{φ φ φ φ} ? ? {x x}_{s the s e e t t} {z z}_{11} {\overset{\cdot \cdot}{I I}}_{φ φ φ φ}}{{z z}_{11} {\overset{\cdot \cdot}{I I}}_{φ φ φ φ} sin sin ((β β + + γ γ))} | | sin sin α α - - - - - - ((22))$

其中：β=Arg(z₁)；

；

。Where: β=Arg(z ₁ );

;

.

由式（2）可得相间短路故障点到输电线路保护安装处的故障距离计算式（3）。From the formula (2), the calculation formula (3) of the fault distance from the phase-to-phase short-circuit fault point to the transmission line protection installation can be obtained.

$x x = = {x x}_{s the s e e t t} ? ? | | \frac{{\overset{\cdot \cdot}{U u}}_{φ φ φ φ} ? ? {x x}_{s the s e e t t} {z z}_{11} {\overset{\cdot \cdot}{I I}}_{φ φ φ φ}}{{z z}_{11} {\overset{\cdot \cdot}{I I}}_{φ φ φ φ} sin sin ((β β + + γ γ))} | | sin sin α α - - - - - - ((33))$

根据测量阻抗Z_φφ,ce=xz₁计算测量阻抗

。Calculate the measured impedance according to the measured impedance Z _φφ,ce =xz ₁

.

由式（3）可知，本发明方法的相间短路故障距离保护的测量阻抗与相间故障点电压、过渡电阻和负荷电流无关。因此，本发明方法在任何故障条件下都能精确测量相间故障点到保护安装处的测量阻抗，在输电线路重负荷情况下本发明方法可靠闭锁，在重负荷输电情况下发生相间高阻短路故障时本发明方法可靠正确动作。It can be known from formula (3) that the measured impedance of the phase-to-phase short-circuit fault distance protection of the method of the present invention has nothing to do with the phase-to-phase fault point voltage, transition resistance and load current. Therefore, the method of the present invention can accurately measure the measured impedance from the phase-to-phase fault point to the protection installation under any fault condition, and the method of the present invention can be reliably blocked under the heavy load condition of the transmission line, and a high-resistance short-circuit fault between phases occurs under the heavy load transmission condition When the method of the present invention is reliable correct action.

以上所述仅为本发明的较佳具体实施例，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。The above descriptions are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto, any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention , should be covered within the protection scope of the present invention.

Claims

1. A transmission line interphase fault relay protection method, characterized in that: comprising the steps,

(1) Measure the fault phase-to-phase voltage at the installation of transmission line protection

, fault current between phases

and normal phase negative sequence current

;in

φφ is AB phase or BC phase or CA phase respectively; Ψ corresponds to C phase or A phase or B phase respectively,

(2) Calculate the measured impedance Z _φφ,ce from the phase-to-phase short-circuit fault point to the transmission line protection installation:

{Z Z}_{φφ φφ,, ce ce} = = (({x x}_{set set} - - | | \frac{{\overset{\cdot \cdot}{U u}}_{φφ φφ} - - {x x}_{set set} {z z}_{11} {\overset{\cdot \cdot}{I I}}_{φφ φφ}}{{z z}_{11} {\overset{\cdot \cdot}{I I}}_{φφ φφ} sin sin ((β β + + γ γ))} | | sin sin α α)) {z z}_{11}

in,

is the fault phase-to-phase voltage;

is the fault current between phases;

is the normal phase negative sequence current; φφ are AB phase or BC phase respectively

or CA phase; Ψ corresponds to C phase, A phase or B phase respectively; x _set is protection setting range; β=Arg(z ₁ ); ;

; z ₁ is the positive sequence impedance of the transmission line per unit length;

Indicates the normal phase negative sequence current

The current phasor rotated 90° counterclockwise,