CN105203903A - Electric transmission line phase-to-phase fault direction recognizing method based on dynamic data window - Google Patents

Abstract

The invention discloses an electric transmission line phase-to-phase fault direction recognizing method based on a dynamic data window. The method comprises the steps that a fault phase-to-phase voltage sampling value, a fault phase-to-phase current sampling value and a fault phase-to-phase negative sequence voltage sampling value at each sampling time at an electric transmission line protective installation position are measured, the length of the dynamic data window is calculated, a fault phase-to-phase electric quantity sampling valve of the length of the dynamic data window is utilized for calculating whether electric line phase-to-phase short-circuit fault direction criterion is set up or not; if yes, it is judged that the electric transmission line positive direction has a phase-to-phase short-circuit fault. Only fault phase-to-phase electric quantity sampling values of the data window within a 1/4 period are used for operation, the algorithm principle is simple, the program is easy to achieve, the number of needed data windows is small, the calculation quantity is small, and the operation speed is high. According to the method, a recognition result is not affected by an electric system running way or a fault position or the transmission resistance or the load current or the other factors, and the electric transmission line phase-to-phase fault direction can be judged accurately.

Description

Discrimination method of phase-to-phase fault direction of transmission line based on dynamic data window

technical field

The invention relates to the technical field of electric power system relay protection, in particular to a method for judging the fault direction between phases of a transmission line based on a dynamic data window.

Background technique

In the actual power grid, the fault point may be located in the opposite direction of the transmission line, or in the forward direction of the transmission line. If the fault point is located in the opposite direction of the transmission line, the relay protection device of the protected line will not act, but the relay protection device of the adjacent line will act to isolate the fault. If the fault point is located in the positive direction of the transmission line, the relay protection device of the protected line will act to isolate the fault on the protected line. The existing transmission line direction discrimination elements mainly include zero sequence power directional element, negative sequence power directional element and zero sequence directional element, negative sequence directional element, zero sequence power directional element, negative sequence power directional element and zero sequence directional element, negative sequence The electrical quantities used in the directional element algorithm are all phasors, which require a whole wave of data windows to participate in the calculation, involving relatively complex Fourier algorithm calculations, so the traditional transmission line direction determination elements are not real-time. If the fault is located at the opposite end of the protected line, the phase current power frequency variation, negative sequence current and zero sequence current protection criteria will act quickly. At this time, the traditional transmission line direction determination element will not be able to block the relay protection device in time. , cause the relay protection device of the protected line to malfunction, cause the scope of the fault to expand, and impact the stability of the power grid, which is not conducive to the safe and stable operation of the power grid.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a method for discriminating the fault direction between phases of a transmission line based on a dynamic data window. The method of the invention measures the sampled value of the fault phase voltage, the fault phase current and the fault phase negative sequence voltage sampling value at each sampling time at the installation place of the transmission line protection, calculates the length of the dynamic data window, and utilizes a fault phase electrical fault with a dynamic data window length Calculate the phase-to-phase short-circuit fault direction criterion of the transmission line based on the sampled values of the transmission line. The method of the invention only needs to use the sampling value of the faulty phase-to-phase electric quantity less than 1/4 cycle data window to participate in the calculation, the algorithm principle is simple, the program is easy to realize, the required data window is small, the calculation amount is small, and the calculation speed is fast. The identification result of the method of the invention is not affected by factors such as power system operation mode, fault location, transition resistance and load current, and can accurately determine the fault direction of the phase-to-phase short-circuit fault of the transmission line.

For accomplishing above-mentioned object, the present invention adopts following technical scheme:

The method for discriminating the fault direction between phases of a transmission line based on a dynamic data window is characterized in that it includes the following sequential steps:

(1) The protection device collects in real time the sampled value of the fault phase-to-phase voltage, the sampled value of the fault-phase current and the sampled value of the fault-phase negative-sequence voltage at each sampling time of the transmission line protection installation;

(2) The protection device calculates the length of the dynamic data window Among them, z ₁ is the positive sequence impedance of the transmission line per unit length; Arg(z ₁ ) is the phase angle of the positive sequence impedance z ₁ of the transmission line per unit length; N is the number of sampling points per cycle;

(3) Protection device judgment $u_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{\left|z_1\right|}-u_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{\left|z_1\right|}<0$ Whether it is established, if established, then judge $\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-2\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t\right)}{\left|z_1\right|}-\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t\right)}{\left|z_1\right|}<0$ Whether it is established, if established, the protection device judges that a phase-to-phase short circuit fault occurs in the positive direction of the transmission line;

(4) Protection device judgment $u_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{\left|z_1\right|}-u_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{\left|z_1\right|}>0$ Whether it is established, if established, then judge $\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-2\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t\right)}{\left|z_1\right|}-\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t\right)}{\left|z_1\right|}>0$ Whether it is established, if established, the protection device judges that a phase-to-phase short circuit fault occurs in the positive direction of the transmission line;

Among them, u _φφ (t), u _φφ (t-Δt) are the sampling values of fault phase-to-phase voltage at sampling time t and t-Δt respectively; u _φφ2 (t-LΔt), u _φφ2 (t-LΔt-Δt) are respectively Sampling values of negative sequence voltage between fault phases at sampling time t-LΔt, t-LΔt-Δt; i _φφ (t), i _φφ (t-Δt), i _φφ (t-2Δt) are t, t-Δt, t Sampling value of current between fault phases at -2Δt sampling time; Δt is the sampling interval time; l ₁ and r ₁ are the positive sequence inductance and positive sequence resistance of the transmission line per unit length respectively; φφ=AB, BC, CA phase _- to-phase; The magnitude of the positive sequence impedance z ₁ of the transmission line per unit length.

Compared with the prior art, the present invention has the following positive results:

The method of the invention measures the sampled value of the fault phase voltage, the fault phase current and the fault phase negative sequence voltage sampling value at each sampling time at the installation place of the transmission line protection, calculates the length of the dynamic data window, and utilizes a fault phase electrical fault with a dynamic data window length Calculate the phase-to-phase short-circuit fault direction criterion of the transmission line based on the sampled values of the transmission line. The method of the invention only needs to use the sampling value of the faulty phase-to-phase electric quantity less than 1/4 cycle data window to participate in the calculation, the algorithm principle is simple, the program is easy to realize, the required data window is small, the calculation amount is small, and the calculation speed is fast. The identification result of the method of the invention is not affected by factors such as power system operation mode, fault location, transition resistance and load current, and can accurately determine the fault direction of the phase-to-phase short-circuit fault of the transmission line.

Description of drawings

Fig. 1 is a schematic diagram of a line transmission system applying the present invention.

Detailed ways

The technical solution of the present invention will be further described in detail according to the accompanying drawings.

Fig. 1 is a schematic diagram of a line transmission system applying the present invention. In Fig. 1, CVT is a voltage transformer, and CT is a current transformer. The protection device collects in real time the sampling values of the fault phase-to-fault voltage, the fault-phase current and the fault-phase negative-sequence voltage at each sampling time where the transmission line protection is installed.

The protection device calculates the phase angle Arg(z ₁ ) of the positive sequence impedance z ₁ of the transmission line per unit length.

The protection device calculates the magnitude |z ₁ | of the positive sequence impedance z ₁ of the transmission line per unit length.

The protection device calculates the length of the dynamic data window Among them, N is the number of sampling points per cycle.

Protection device judgment $u_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{\left|z_1\right|}-u_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{\left|z_1\right|}<0$ Whether it is established, if established, then judge $\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-2\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t\right)}{\left|z_1\right|}-\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t\right)}{\left|z_1\right|}<0$ Whether it is established, and if established, the protection device judges that a phase-to-phase short circuit fault occurs in the positive direction of the transmission line.

Protection device judgment $u_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{\left|z_1\right|}-u_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{\left|z_1\right|}>0$ Whether it is established, if established, then judge $\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-2\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t\right)}{\left|z_1\right|}-\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t-\mathrm{\&Delta;}t\right)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}\left(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t\right)}{\left|z_1\right|}>0$ Whether it is established, and if established, the protection device judges that a phase-to-phase short circuit fault occurs in the positive direction of the transmission line.

Among them, u _φφ (t), u _φφ (t-Δt) are the sampling values of fault phase-to-phase voltage at sampling time t and t-Δt respectively; u _φφ2 (t-LΔt), u _φφ2 (t-LΔt-Δt) are respectively Sampling values of negative sequence voltage between fault phases at sampling time t-LΔt, t-LΔt-Δt; i _φφ (t), i _φφ (t-Δt), i _φφ (t-2Δt) are t, t-Δt, t Sampling value of fault phase-to-phase current at -2Δt sampling time; Δt is sampling interval time; l ₁ and r ₁ are positive sequence inductance and positive sequence resistance of transmission line per unit length respectively; φφ=AB, BC, CA phase-to-phase.

The method of the invention measures the sampled value of the fault phase voltage, the fault phase current and the fault phase negative sequence voltage sampling value at each sampling time at the installation place of the transmission line protection, calculates the length of the dynamic data window, and utilizes a fault phase electrical fault with a dynamic data window length Calculate the phase-to-phase short-circuit fault direction criterion of the transmission line based on the sampled values of the transmission line. The method of the invention only needs to use the sampling value of electrical quantities between fault phases with a short data window of less than 1/4 period to participate in the calculation, the algorithm principle is simple, the implementation is easy, the required data windows are small, the calculation amount is small, and the calculation speed is fast. The identification result of the method of the invention is not affected by factors such as power system operation mode, fault location, transition resistance and load current, and can accurately determine the fault direction of the phase-to-phase short-circuit fault of the transmission line.

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)

1. A method for discriminating the fault direction between phases of a transmission line based on a dynamic data window, including the following sequential steps: (1) The protection device collects in real time the sampled value of the fault phase-to-phase voltage, the sampled value of the fault-phase current and the sampled value of the fault-phase negative-sequence voltage at each sampling time of the transmission line protection installation; (2) The protection device calculates the length of the dynamic data window Among them, z ₁ is the positive sequence impedance of the transmission line per unit length; Arg(z ₁ ) is the phase angle of the positive sequence impedance z ₁ of the transmission line per unit length; N is the number of sampling points per cycle; (3) Protection device judgment $u_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{|z_1|}-u_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{|z_1|}<0$ Whether it is established, if established, then judge $\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-2\mathrm{\&Delta;}t)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{|z_1|}-\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{|z_1|}<0$ Whether it is established, if established, the protection device judges that a phase-to-phase short circuit fault occurs in the positive direction of the transmission line; (4) Protection device judgment $u_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{|z_1|}-u_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{|z_1|}>0$ Whether it is established, if established, then judge $\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-2\mathrm{\&Delta;}t)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t)}{|z_1|}-\&lsqb;l_1\frac{i_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)-i_{\mathrm{\&phi;}\mathrm{\&phi;}}(t-\mathrm{\&Delta;}t)}{\mathrm{\&Delta;}t}+r_1{i}_{\mathrm{\&phi;}\mathrm{\&phi;}}\left(t\right)\&rsqb;\frac{u_{\mathrm{\&phi;}\mathrm{\&phi;}2}(t-L\mathrm{\&Delta;}t-\mathrm{\&Delta;}t)}{|z_1|}>0$ Whether it is established, if established, the protection device judges that a phase-to-phase short circuit fault occurs in the positive direction of the transmission line; Among them, u _φφ (t), u _φφ (t-Δt) are the sampling values of fault phase-to-phase voltage at sampling time t and t-Δt respectively; u _φφ2 (t-LΔt), u _φφ2 (t-LΔt-Δt) are respectively Sampling values of negative sequence voltage between fault phases at sampling time t-LΔt, t-LΔt-Δt; i _φφ (t), i _φφ (t-Δt), i _φφ (t-2Δt) are t, t-Δt, t Sampling value of current between fault phases at -2Δt sampling time; Δt is the sampling interval time; l ₁ and r ₁ are the positive sequence inductance and positive sequence resistance of the transmission line per unit length respectively; φφ=AB, BC, CA phase _- to-phase; The magnitude of the positive sequence impedance z ₁ of the transmission line per unit length.