CN103199508A - Method for achieving electric transmission line single phase grounding fault relay protection by using distribution parameter - Google Patents

Abstract

The invention discloses a single-phase grounding fault relay protection method for a power transmission line by using distributed parameters. This method uses the long-line equation to accurately describe the physical characteristics of transmission line voltage and current transmission, and uses the fault phase electric quantity at the protection installation to calculate the transmission line fault impedance amplitude from the transmission line protection installation to the single-phase ground fault point, and compares the transmission line The magnitude relationship between the fault impedance amplitude and the transmission line protection setting impedance amplitude. If the transmission line fault impedance amplitude is smaller than the transmission line protection setting impedance amplitude, the protection will send an action trip signal. Applying the method of the present invention as a single-phase ground fault relay protection for UHV AC transmission lines can accurately calculate the fault impedance amplitude, and its action performance is not affected by ground fault point voltage, distributed capacitive current, transition resistance and load current. The performance meets the requirements of relay protection selectivity, reliability, sensitivity and quick action.

Description

Using Distributed Parameters to Realize the Relay Protection Method of Transmission Line Single-phase Grounding Fault

technical field

The invention relates to the technical field of electric power system relay protection, in particular to a method for realizing single-phase ground fault relay protection of transmission lines by using a distributed parameter model. the

Background technique

Since distance protection is less affected by power system operation mode and structural changes, it can selectively remove various faults in transmission lines instantly, and has been widely used in power system transmission line protection. The distance protection on the high-voltage transmission line is used as the main protection of the transmission line, and the distance protection on the EHV/UHV AC transmission line is used as the backup protection of the transmission line. At present, the distance protection widely used in power system transmission lines mainly includes power frequency variation distance protection and impedance distance protection. the

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. the

Impedance distance protection reflects the fault distance length according to the fault impedance to distinguish whether the fault point is inside the protection zone 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 fault impedance is the total fault component, which is applicable to 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. the

However, the premise of the traditional grounding impedance distance protection is that the voltage of the grounding fault point is zero, and the fault impedance is calculated by the ratio of the fault phase voltage to the fault phase current, and the distance of the fault point is reflected according to the magnitude of the fault impedance to determine whether to send a trip signal. In fact, in the power system, the voltage at the ground fault point is almost impossible to be zero except for the artificially constructed metallic ground short-circuit fault. Therefore, the voltage at the ground fault point will have a serious impact on the performance of the ground impedance distance protection. the

In the actual power system, the voltage and current transmission of UHV AC transmission lines have obvious wave process, and the distributed capacitive current along the line is large, so the influence on the performance of impedance distance protection cannot be ignored. Considering the influence of the ground capacitance along the line, the relationship between the fault impedance and the fault distance is a hyperbolic tangent function. The characteristics of the hyperbolic tangent function determine that the resistance of the impedance relay is poor, and the additional impedance brought by the transition resistance will seriously affect the impedance relay. action performance. The UV AC transmission line transmits large-capacity electric energy, and it is a heavy-duty transmission line. The heavy-load current will reduce the action sensitivity of the impedance distance protection, and the impact of the heavy-load current on the action performance of the impedance distance protection cannot be ignored. the

According to the statistics of the State Grid Corporation of China, single-phase ground faults account for more than 80% of the various fault types that occur in power system transmission lines. Therefore, it is very important to study a relay protection method suitable for single-phase ground faults in UHV AC transmission lines. engineering significance. the

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a relay protection method suitable for UHV AC transmission lines using a distributed parameter model to realize single-phase grounding faults in transmission lines. the

The purpose of the present invention is achieved by the following approach:

Using the distributed parameter model to realize the single-phase ground fault relay protection method of transmission line, the main point is that it includes the following steps:

故障相电流

故障相负序电流和零序电流其中，φ=A、B、C相；  (1) Provide a protective device that measures the fault phase voltage at the installation of the transmission line protection

fault phase current

Fault phase negative sequence current and zero sequence current Among them, φ=A, B, C phase;

(2) The protection device calculates the fault impedance amplitude |Z _φ | of the φ-phase transmission line by using the measured electrical quantity of the fault phase:

$<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}}{{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; ch</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; sh</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; ch</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; sh</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span>$

Among them, φ=phases A, B, and C; l _set is the protection setting range; Z ₀ is the zero-sequence equivalent impedance of the system where the transmission line protection is installed; γ ₁ and γ ₀ are the transmission line positive-sequence and zero-sequence propagation coefficients respectively ; Z _c1 , Z _c0 are positive-sequence and zero-sequence wave impedances of the transmission line respectively; $\mathrm{\&gamma;}=\mathrm{Arg}\left(\frac{{\stackrel{\&Center\; Dot;}{I}}_{\mathrm{\&phi;}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\&Center\; Dot;}{I}}_0}{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}2}}\right);$ $\mathrm{\&beta;}=\mathrm{Arg}\left(\frac{{\stackrel{\&CenterDot;}{u}}_{\mathrm{\&phi;}}}{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}2}}\right);$ ch(.) is a hyperbolic cosine function; α=Arg(Z _c1 th(γ ₁ l _set )); sh(.) is a hyperbolic sine function.

(3) The protection device further calculates the protection setting impedance amplitude |Z _c1 th(γ ₁ l _set )| of the φ-phase transmission line, where th(.) is a hyperbolic tangent function;

(4) The protection device compares the size relationship between |Z _c1 th(γ ₁ l _set )| and |Z _φ |, if it satisfies |Z _φ |<|Z _c1 th(γ ₁ l _set )|, then the protection will send out Action trip signal.

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

(1) The method of the present invention uses the long-term equation to accurately describe the physical characteristics of the transmission line, and has a natural ability to resist the influence of distributed capacitance. the

(2) The method of the present invention can accurately calculate the fault impedance amplitude of the transmission line, and is used as a single-phase ground fault relay protection of the UHV AC transmission line, and its operating performance is not affected by the ground fault point voltage, distributed capacitive current, transition resistance and load current. The impact, the action performance is stable and reliable. the

Description of drawings

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

Detailed ways

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

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 samples the voltage waveform of the voltage transformer CVT 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. the

故障相电流

故障相负序电流

和零序电流

其中，φ=A、B、C相。  The protection device uses the Fourier algorithm to calculate the fault phase voltage at the protection installation of the transmission line on the instantaneous value of the voltage and current obtained by sampling

fault phase current

Fault phase negative sequence current

and zero sequence current

Among them, φ=A, B, C phase.

The protection device calculates the fault impedance amplitude |Z _φ | of the φ-phase transmission line by using the measured fault phase electrical quantity:

$<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}}{{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; ch</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; sh</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; ch</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; sh</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; set</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span>$

Among them, φ=phases A, B, and C; l _set is the protection setting range; Z ₀ is the zero-sequence equivalent impedance of the system where the transmission line protection is installed; γ ₁ and γ ₀ are the transmission line positive-sequence and zero-sequence propagation coefficients respectively ; Z _c1 , Z _c0 are the positive-sequence and zero-sequence wave impedances of the transmission line respectively; $\mathrm{\&gamma;}=\mathrm{Arg}\left(\frac{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\&Center\; Dot;}{I}}_0}{{\stackrel{\&Center\; Dot;}{I}}_{\mathrm{\&phi;}2}}\right);$ $\mathrm{\&beta;}=\mathrm{Arg}\left(\frac{{\stackrel{\&CenterDot;}{u}}_{\mathrm{\&phi;}}}{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}2}}\right);$ ch(.) is a hyperbolic cosine function; α=Arg(Z _c1 th(γ ₁ l _set )); sh(.) is a hyperbolic sine function.

The protection device further calculates the protection setting impedance amplitude |Z _c1 th(γ ₁ l _set )| of the φ-phase transmission line, where th(.) is a hyperbolic tangent function.

The protection device compares the size relationship between |Z _c1 th(γ ₁ l _set )| and |Z _φ |, if it satisfies |Z _φ |<|Z _c1 th(γ ₁ l _set )|, then the protection sends out an action trip signal .

Applying the method of the present invention as a single-phase ground fault relay protection for UHV AC transmission lines can accurately calculate the fault impedance amplitude, and its action performance is not affected by ground fault point voltage, distributed capacitive current, transition resistance and load current. The performance meets the requirements of relay protection selectivity, reliability, sensitivity and quick action. the

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. the

Claims (1)

1. utilize distributed constant to realize the transmission line one-phase earth fault relay protecting method, comprise the following steps:

(1) provides a kind of protective device, the fault phase voltage of this protector measuring line protection installation place

The fault phase current

Fault phase negative-sequence current

And zero-sequence current Wherein, φ=A, B, C phase;

(2) protective device utilizes its fault phase electric parameters that measures to calculate the fault impedance amplitude of φ phase transmission line | Z _φ|:

$\left|Z_{\mathrm{\&phi;}}\right|=\left|\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;}}}{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\&CenterDot;}{I}}_0}\frac{\sin \mathrm{\&beta;}}{\sin (\mathrm{\&alpha;}+\mathrm{\&gamma;})}\right|$

Wherein, φ=A, B, C phase; l _SetBe the protection setting range; Z ₀System's zero sequence equivalent impedance for the line protection installation place; γ ₁, γ ₀Be respectively transmission line positive sequence, zero sequence propagation coefficient; Z _C1, Z _C0Be respectively transmission line positive sequence, zero sequence wave impedance; $\mathrm{\&gamma;}=\mathrm{Arg}\left(\frac{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\&gamma;}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\&gamma;}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\&CenterDot;}{I}}_0}{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}2}}\right);$ $\mathrm{\&beta;}=\mathrm{Arg}\left(\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;}}}{{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;}2}}\right);$ Ch (.) is hyperbolic cosine function; α=Arg (Z _C1Th (γ ₁l _Set)); Sh (.) is hyperbolic sine function.

(3) the protective device protection of further the calculating φ phase transmission line impedance magnitude of adjusting | Z _C1Th (γ ₁l _Set) |, wherein, th (.) is hyperbolic tangent function;

(4) protective device is relatively | Z _C1Th (γ ₁l _Set) | with | Z _φ| between magnitude relationship, if satisfy | Z _φ|＜| Z _C1Th (γ ₁l _Set) |, then the would trip signal is sent in protection.

Images