CN102694374A - Power transmission line differential protection method based on current traveling wave prediction - Google Patents

Abstract

The invention discloses a power transmission line differential protection method based on current traveling wave prediction. The method is characterized by comprises the following steps: firstly, collecting voltage and current traveling wave component of each sampling time at the two ends of a power transmission line; predicating the current traveling wave components at the two ends of the power transmission line at each sampling time by utilizing the voltage and current traveling wave component at the front 1/4 period time of each sampling time; and secondly, forming current traveling wave differential protection on the predicated and obtained current traveling wave component at each sampling time and the current traveling wave component obtained by sampling at each time respectively at the two ends of the power transmission line by utilizing the conventional proportion braking characteristic, and protecting the sending of trip signals to circuit breakers at the two ends of the circuit if any current traveling wave differential protection of the current traveling wave differential protection at the two ends of the power transmission line acts. According to the invention, the current traveling wave component of each sampling time is not solved through interpolation operation, thus the traveling wave protection operation amount is reduced, the fault traveling wave protection function in the short data window of the 1/4 period can be completed, and the protection action speed is fast.

Description

A kind of differential guard method of transmission line based on the current traveling wave prediction

Technical field

The present invention relates to the differential guard method of a kind of transmission line and, particularly a kind of differential guard method of transmission line based on current traveling wave prediction.

Background technology

Owing to not influenced by system operation mode and electric network composition and have natural phase-selecting function, current differential protection is the main protection of various electric pressure transmission lines always.In 220kV and following electric pressure transmission line, because transmission line capacitance current along the line is very little, distributed capacitance is very little to the influence of current differential protection performance.Yet; The voltage of ultra-high/extra-high voltage transmission line of alternation current, current delivery have tangible wave process; Capacitance current along the line is very big, utilize two ends fundamental frequency steady-state current component vector and amplitude to be faced with the current differential protection starting current as the conventional current differential protection of actuating quantity big, and in order to prevent to protect malfunction; Improve the startup set point and can cause protecting sensitivity not enough again, restricting the application of conventional current differential protection on the ultra-high/extra-high voltage transmission line of alternation current.

Traveling-wave differential protection has been considered the influence of distributed capacitance in protection algorithm familiar models, do not receive the influence of transmission line distributed capacitance on the traveling-wave differential protection principle, has very high performance.Application number 200910034669.1 patents of invention " are applicable to the traveling-wave differential protection method of series capacitor compensated line " and have solved the influence of distributed capacitance to the differential protection performance; But for row ripple propagation delay is the situation in non-integral multiple sampling interval; Need obtain the electric parameters on each time point through interpolation arithmetic; Requirement to the protective device sample frequency is very high, and is therefore very high to the protective device hardware requirement, and each sampling time all will be carried out interpolation arithmetic; The required operand of protection algorithm itself is big, can't satisfy the requirement of protection quick-action property.The situation that " based on the traveling-wave differential protection of wavelet transformation " and the application number 200410079501.X patent of invention " detection method of voltage zero-cross annex fault in the traveling-wave protection " of " traveling-wave differential protection of extra-high-speed pressure zone shunt reactor circuit " of Su Bin, Dong Xinzhou and Sun Yuan Zhang Fabiao and Su Bin, Dong Xinzhou and Sun Yuan Zhang Fabiao is the non-integral multiple sampling interval for capable ripple propagation delay also need obtain the electric parameters on each time point through interpolation arithmetic, exists the big problem of operand equally; Need carry out wavelet transformation, the desired data window is big, and it is long that protection detects fault generation required time.

At present; The situation that the transmission line travelling wave differential protecting method that many scholars have proposed is the non-integral multiple sampling interval to capable ripple propagation delay all need be carried out interpolation arithmetic and asked the electric parameters on its each time point; The operand of protection algorithm own is big, and is high to protective device sampling hardware requirement.Part transmission line travelling wave differential protecting method even need carry out wavelet transformation wherein, the desired data window is big, has prolonged protection and has detected the time that fault takes place, and can't satisfy the requirement of relaying protection to quick-action property.

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, a kind of current traveling wave component that need not to ask through interpolation arithmetic its each sampling instant is provided, reduced the differential guard method of transmission line based on the current traveling wave prediction of traveling-wave protection operand.

The present invention adopts following technical scheme:

A kind of differential guard method of transmission line based on the current traveling wave prediction, its step is following: the three-phase voltage traveling-wave component u of transmission line in each sampling instant at m transformer station test point place gathered in (1) _MA(t), u _MB(t), u _MC(t), three-phase current traveling-wave component i _MA(t), i _MB(t), i _MC(t); Gather the three-phase voltage traveling-wave component u of transmission line in each sampling instant of test point place of n transformer station _NA(t), u _NB(t), u _NC(t), three-phase current traveling-wave component i _NA(t), i _NB(t), i _NC(t), as input variable.

(2) adopt phase-model transformation, with three-phase voltage traveling-wave component, the three-phase current traveling-wave component of each sampling instant at m transformer station test point place convert 0 to, α, β line wave component u _M0(t), u _{M α}(t), u _{M β}(t) and i _M0(t), i _{M α}(t), i _{M β}(t); With three-phase voltage traveling-wave component, the three-phase current traveling-wave component of each sampling instant at n transformer station test point place convert 0 to, α, β line wave component u _N0(t), u _{M α}(t), u _{N β}(t) and i _N0(t), i _{M α}(t), i _{N β}(t).

(3) utilize constantly 0, α, β line wave component prediction t constantly m transformer station test point place 0, α, β mould current traveling wave component:

$i_{m0}^{\′}\left(t\right)=\frac{u_{m0}(t-\frac{T}{4})}{Z_{c0}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_0})}{\sin (100\mathrm{\π}*\frac{l}{v_0})}-\frac{u_{n0}(t-\frac{T}{4})}{Z_{c0}\sin (100\mathrm{\π}*\frac{l}{v_0})}$

$i_{\mathrm{m\α}}^{\′}\left(t\right)=\frac{u_{\mathrm{m\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}-\frac{u_{\mathrm{n\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}$

$i_{\mathrm{m\β}}^{\′}\left(t\right)=\frac{u_{\mathrm{m\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}-\frac{u_{\mathrm{n\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}$

Wherein, l is a transmission line length; T is the cycle time of fundamental component; Z _C0, Z _{C α}, Z _{C β}Be respectively the characteristic impedance of transmission line 0, α, β line wave component; v ₀, v _α, v _βBe respectively the propagation velocity of transmission line 0, α, β line wave component.

(4) utilize

constantly 0, α, β line wave component prediction t constantly n transformer station test point place 0, α, β mould current traveling wave component:

$i_{n0}^{\′}\left(t\right)=\frac{u_{n0}(t-\frac{T}{4})}{Z_{c0}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_0})}{\sin (100\mathrm{\π}*\frac{l}{v_0})}-\frac{u_{m0}(t-\frac{T}{4})}{Z_{c0}\sin (100\mathrm{\π}*\frac{l}{v_0})}$

$i_{\mathrm{n\α}}^{\′}\left(t\right)=\frac{u_{\mathrm{n\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}-\frac{u_{\mathrm{m\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}$

$i_{\mathrm{n\β}}^{\′}\left(t\right)=\frac{u_{\mathrm{n\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}-\frac{u_{\mathrm{m\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}$

Wherein, l is a transmission line length; T is the cycle time of fundamental component; Z _C0, Z _{C α}, Z _{C β}Be respectively the characteristic impedance of transmission line 0, α, β line wave component; v ₀, v _α, v _βBe respectively the propagation velocity of transmission line 0, α, β line wave component.

(5) prediction is obtained the i ' of each sampling instant _M0(t), i ' _{M α}(t), i ' _{M β}(t) traveling-wave component carries out the three-phase current traveling-wave component i ' of each sampling instant that phase mould inverse transformation obtains m transformer station test point place _MA(t), i ' _MB(t), i ' _MC(t); Prediction is obtained the i ' of each sampling instant _N0(t), i ' _{N α}(t), i ' _{N β}(t) traveling-wave component carries out the three-phase current traveling-wave component i ' of each sampling instant that phase mould inverse transformation obtains n transformer station test point place _NA(t), i ' _NB(t), i ' _NC(t).

(6) obtain the three-phase current traveling-wave component i of each sampling instant by m transformer station test point place sampling _MA(t), i _MB(t), i _MC(t) with the three-phase current traveling-wave component i ' that predicts each sampling instant that obtains _MA(t), i ' _MB(t), i ' _MC(t) utilize conventional ratio braking characteristic to constitute traveling-wave differential protection, if the action of arbitrary phase current traveling-wave differential protection is then protected to the circuit breaker at these phase circuit two ends and sent out trip signal.

(7) obtain the three-phase current traveling-wave component i of each sampling instant by n transformer station test point place sampling _NA(t), i _NB(t), i _NC(t) with the three-phase current traveling-wave component i ' that predicts each sampling instant that obtains _NA(t), i ' _NB(t), i ' _NC(t) utilize conventional ratio braking characteristic to constitute traveling-wave differential protection, if the action of arbitrary phase current traveling-wave differential protection is then protected to the circuit breaker at these phase circuit two ends and sent out trip signal.

The present invention has following positive achievement compared with prior art:

This method is at first gathered voltage, the current traveling wave component of each sampling instant of transmission line two ends; Utilize voltage, the current traveling wave component constantly of preceding 1/4 cycle of each sampling instant to predict the current traveling wave component at the transmission line two ends of each sampling instant; The current traveling wave component of each sampling instant that respectively prediction is obtained at the transmission line two ends and sampling obtain each constantly current traveling wave component utilize conventional ratio braking characteristic to constitute the current traveling wave differential protection; If arbitrary phase current traveling-wave differential protection action of transmission line two ends current traveling wave differential protection is then protected to the circuit breaker at these phase circuit two ends and is sent out trip signal.Adopt the differential guard method of transmission line based on the current traveling wave prediction of this method; Need not to ask the current traveling wave component of its each sampling instant through interpolation arithmetic; Reduced the traveling-wave protection operand; Can in the short data window in 1/4 cycle, accomplish the fault traveling wave defencive function, the protection quick action is applicable to the traveling-wave protection of whole transient state failure process of the transmission line of various electric pressures.

Description of drawings

Fig. 1 is a kind of differential guard method flow chart of transmission line based on the current traveling wave prediction of the present invention.

Embodiment

Below in conjunction with embodiment the present invention is described in more detail.

Embodiment 1

According to Figure of description technical scheme of the present invention is done further detailed presentations below.

Fig. 1 is a kind of differential guard method flow chart of transmission line based on the current traveling wave prediction of the present invention.Present embodiment is at first gathered the three-phase voltage traveling-wave component u of transmission line in each sampling instant at m transformer station test point place _MA(t), u _MB(t), u _MC(t), three-phase current traveling-wave component i _MA(t), i _MB(t), i _MC(t); Gather the three-phase voltage traveling-wave component u of transmission line in each sampling instant at n transformer station test point place _NA(t), u _NB(t), u _NC(t), three-phase current traveling-wave component i _NA(t), i _NB(t), i _NC(t).

Adopt phase-model transformation, with three-phase voltage traveling-wave component, the three-phase current traveling-wave component of each sampling instant at m transformer station test point place convert 0 to, α, β line wave component u _M0(t), u _{M α}(t), u _{M β}(t) and i _M0(t), i _{M α}(t), i _{M β}(t):

$\left[\begin{array}{c}{i}_{m0}\left(t\right)\\ i_{\mathrm{m\α}}\left(t\right)\\ i_{\mathrm{m\β}}\left(t\right)\end{array}\right]={\left[\begin{array}{ccc}1& 2& 1\\ 1& -1& 0\\ 1& -1& -1\end{array}\right]}^{-1}\left[\begin{array}{c}{i}_{\mathrm{mA}}\left(t\right)\\ i_{\mathrm{mB}}\left(t\right)\\ i_{\mathrm{mC}}\left(t\right)\end{array}\right]$

$\left[\begin{array}{c}{u}_{m0}\left(t\right)\\ u_{\mathrm{m\α}}\left(t\right)\\ u_{\mathrm{m\β}}\left(t\right)\end{array}\right]={\left[\begin{array}{ccc}1& 2& 1\\ 1& -1& 0\\ 1& -1& -1\end{array}\right]}^{-1}\left[\begin{array}{c}{u}_{\mathrm{mA}}\left(t\right)\\ u_{\mathrm{mB}}\left(t\right)\\ u_{\mathrm{mC}}\left(t\right)\end{array}\right]$

With three-phase voltage traveling-wave component, the three-phase current traveling-wave component of each sampling instant at n transformer station test point place convert 0 to, α, β line wave component u _N0(t), u _{N α}(t), u _{N β}(t) and i _N0(t), i _{N α}(t), i _{N β}(t):

$\left[\begin{array}{c}{i}_{n0}\left(t\right)\\ i_{\mathrm{n\α}}\left(t\right)\\ i_{\mathrm{n\β}}\left(t\right)\end{array}\right]={\left[\begin{array}{ccc}1& 2& 1\\ 1& -1& 0\\ 1& -1& -1\end{array}\right]}^{-1}\left[\begin{array}{c}{i}_{\mathrm{nA}}\left(t\right)\\ i_{\mathrm{nB}}\left(t\right)\\ i_{\mathrm{nC}}\left(t\right)\end{array}\right]$

$\left[\begin{array}{c}{u}_{n0}\left(t\right)\\ u_{\mathrm{n\α}}\left(t\right)\\ u_{\mathrm{n\β}}\left(t\right)\end{array}\right]={\left[\begin{array}{ccc}1& 2& 1\\ 1& -1& 0\\ 1& -1& -1\end{array}\right]}^{-1}\left[\begin{array}{c}{u}_{\mathrm{nA}}\left(t\right)\\ u_{\mathrm{nB}}\left(t\right)\\ u_{\mathrm{nC}}\left(t\right)\end{array}\right]$

Utilize constantly 0, α, β line wave component prediction t constantly m transformer station test point place 0, α, β mould current traveling wave component:

$i_{m0}^{\′}\left(t\right)=\frac{u_{m0}(t-\frac{T}{4})}{Z_{c0}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_0})}{\sin (100\mathrm{\π}*\frac{l}{v_0})}-\frac{u_{n0}(t-\frac{T}{4})}{Z_{c0}\sin (100\mathrm{\π}*\frac{l}{v_0})}$

$i_{\mathrm{m\α}}^{\′}\left(t\right)=\frac{u_{\mathrm{m\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}-\frac{u_{\mathrm{n\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}$

$i_{\mathrm{m\β}}^{\′}\left(t\right)=\frac{u_{\mathrm{m\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}-\frac{u_{\mathrm{n\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}$

Wherein, l is a transmission line length; T is the cycle time of fundamental component; Z _C0, Z _{C α}, Z _{C β}Be respectively transmission line 0, the characteristic impedance of α, β line wave component; v ₀, v _α, v _βBe respectively transmission line 0, the propagation velocity of α, β line wave component.

Utilize

constantly 0, α, β line wave component prediction t constantly n transformer station test point place 0, α, β mould current traveling wave component:

$i_{n0}^{\′}\left(t\right)=\frac{u_{n0}(t-\frac{T}{4})}{Z_{c0}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_0})}{\sin (100\mathrm{\π}*\frac{l}{v_0})}-\frac{u_{m0}(t-\frac{T}{4})}{Z_{c0}\sin (100\mathrm{\π}*\frac{l}{v_0})}$

$i_{\mathrm{n\α}}^{\′}\left(t\right)=\frac{u_{\mathrm{n\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}-\frac{u_{\mathrm{m\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}$

$i_{\mathrm{n\β}}^{\′}\left(t\right)=\frac{u_{\mathrm{n\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}-\frac{u_{\mathrm{m\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}$

Wherein, l is a transmission line length; T is the cycle time of fundamental component; Z _C0, Z _{C α}, Z _{C β}Be respectively transmission line 0, the characteristic impedance of α, β line wave component; v ₀, v _α, v _βBe respectively transmission line 0, the propagation velocity of α, β line wave component.

The predicted each sampling time

Sagami wave component of the inverse transform to obtain m substation testing each sampling time point of three-phase power pop wave component

$\left[\begin{array}{c}{i}_{\mathrm{mA}}^{\′}\left(t\right)\\ i_{\mathrm{mB}}^{\′}\left(t\right)\\ i_{\mathrm{mC}}^{\′}\left(t\right)\end{array}\right]=\left[\begin{array}{ccc}1& 2& 1\\ 1& -1& 0\\ 1& -1& -1\end{array}\right]\left[\begin{array}{c}{i}_{m0}^{\′}\left(t\right)\\ i_{\mathrm{m\α}}^{\′}\left(t\right)\\ i_{\mathrm{m\β}}^{\′}\left(t\right)\end{array}\right]$

The predicted each sampling time Sagami wave component of the inverse transform to obtain n station detects each sampling time point of three-phase power pop wave component

$\left[\begin{array}{c}{i}_{\mathrm{nA}}^{\′}\left(t\right)\\ i_{\mathrm{nB}}^{\′}\left(t\right)\\ i_{\mathrm{nC}}^{\′}\left(t\right)\end{array}\right]=\left[\begin{array}{ccc}1& 2& 1\\ 1& -1& 0\\ 1& -1& -1\end{array}\right]\left[\begin{array}{c}{i}_{n0}^{\′}\left(t\right)\\ i_{\mathrm{n\α}}^{\′}\left(t\right)\\ i_{\mathrm{n\β}}^{\′}\left(t\right)\end{array}\right]$

Obtain the three-phase current traveling-wave component i of each sampling instant by the sampling of m transformer station test point place _MA(t), i _MB(t), i _MC(t) with the three-phase current traveling-wave component of predicting each sampling instant that obtains

Utilize conventional ratio braking characteristic to constitute traveling-wave differential protection, if the action of arbitrary phase current traveling-wave differential protection is then protected to the circuit breaker at these phase circuit two ends and sent out trip signal.

Obtain the three-phase current traveling-wave component i of each sampling instant by the sampling of n transformer station test point place _NA(t), i _NB(t), i _NC(t) with the three-phase current traveling-wave component of predicting each sampling instant that obtains

Utilize conventional ratio braking characteristic to constitute traveling-wave differential protection, if the action of arbitrary phase current traveling-wave differential protection is then protected to the circuit breaker at these phase circuit two ends and sent out trip signal.

The above is merely preferred embodiment of the present invention; But protection scope of the present invention is not limited thereto; Any technical staff who is familiar with the present technique field is in the technical scope that the present invention discloses; The variation that can expect easily or replacement all should be encompassed within protection scope of the present invention in sum, and the present invention compares the following advantage of prior art:

It is identical with prior art that present embodiment is not stated part.

Claims (1)

1. differential guard method of transmission line based on the current traveling wave prediction is characterized in that: the three-phase voltage traveling-wave component u of transmission line in each sampling instant at m transformer station test point place gathered in (1) _MA(t), u _MB(t), u _MC(t), three-phase current traveling-wave component i _MA(t), i _MB(t), i _MC(t); Gather the three-phase voltage traveling-wave component u of transmission line in each sampling instant of test point place of n transformer station _NA(t), u _NB(t), u _NC(t), three-phase current traveling-wave component i _NA(t), i _NB(t), i _NC(t), as input variable;

(2) adopt phase-model transformation, with three-phase voltage traveling-wave component, the three-phase current traveling-wave component of each sampling instant at m transformer station test point place convert 0 to, α, β line wave component u _M0(t), u _{M α}(t), u _{M β}(t) and i _M0(t), i _{M α}(t), i _{M β}(t); With three-phase voltage traveling-wave component, the three-phase current traveling-wave component of each sampling instant at n transformer station test point place convert 0 to, α, β line wave component u _N0(t), u _{N α}(t), u _{N β}(t) and i _N0(t), i _{N α}(t), i _{N β}(t);

(3) utilize

constantly 0, α, β line wave component prediction t constantly m transformer station test point place 0, α, β mould current traveling wave component:

$i_{m0}^{\′}\left(t\right)=\frac{u_{m0}(t-\frac{T}{4})}{Z_{c0}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_0})}{\sin (100\mathrm{\π}*\frac{l}{v_0})}-\frac{u_{n0}(t-\frac{T}{4})}{Z_{c0}\sin (100\mathrm{\π}*\frac{l}{v_0})}$

$i_{\mathrm{m\α}}^{\′}\left(t\right)=\frac{u_{\mathrm{m\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}-\frac{u_{\mathrm{n\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}$

$i_{\mathrm{m\β}}^{\′}\left(t\right)=\frac{u_{\mathrm{m\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}-\frac{u_{\mathrm{n\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}$

Wherein, l is a transmission line length; T is the cycle time of fundamental component; Z _C0, A _{C α}, A _{C β}Be respectively the characteristic impedance of transmission line 0, α, β line wave component; v ₀, v _α, v _βBe respectively the propagation velocity of transmission line 0, α, β line wave component;

(4) utilize

constantly 0, α, β line wave component prediction t constantly n transformer station test point place 0, α, β mould current traveling wave component:

$i_{n0}^{\′}\left(t\right)=\frac{u_{n0}(t-\frac{T}{4})}{Z_{c0}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_0})}{\sin (100\mathrm{\π}*\frac{l}{v_0})}-\frac{u_{m0}(t-\frac{T}{4})}{Z_{c0}\sin (100\mathrm{\π}*\frac{l}{v_0})}$

$i_{\mathrm{n\α}}^{\′}\left(t\right)=\frac{u_{\mathrm{n\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}-\frac{u_{\mathrm{m\α}}(t-\frac{T}{4})}{Z_{\mathrm{c\α}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\α}}})}$

$i_{\mathrm{n\β}}^{\′}\left(t\right)=\frac{u_{\mathrm{n\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}}\frac{\cos (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}{\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}-\frac{u_{\mathrm{m\β}}(t-\frac{T}{4})}{Z_{\mathrm{c\β}}\sin (100\mathrm{\π}*\frac{l}{v_{\mathrm{\β}}})}$

Wherein, l is a transmission line length; T is the cycle time of fundamental component; Z _C0, Z _{C α}, Z _{C β}Be respectively the characteristic impedance of transmission line 0, α, β line wave component; v ₀, v _α, v _βBe respectively the propagation velocity of transmission line 0, α, β line wave component;

(5) prediction is obtained the i ' of each sampling instant _M0(t), i ' _{M α}(t), i ' _{M β}(t) traveling-wave component carries out the three-phase current traveling-wave component i ' of each sampling instant that phase mould inverse transformation obtains m transformer station test point place _MA(t), i ' _MB(t), i ' _MC(t); Prediction is obtained the i ' of each sampling instant _N0(t), i ' _{N α}(t), i ' _{N β}(t) traveling-wave component carries out the three-phase current traveling-wave component i ' of each sampling instant that phase mould inverse transformation obtains n transformer station test point place _NA(t), i ' _NB(t), i ' _NC(t);

(6) obtain the three-phase current traveling-wave component i of each sampling instant by m transformer station test point place sampling _MA(t), i _MB(t), i _MC(t) with the three-phase current traveling-wave component i ' that predicts each sampling instant that obtains _MA(t), i ' _MB(t), i ' _MC(t) utilize conventional ratio braking characteristic to constitute traveling-wave differential protection, if the action of arbitrary phase current traveling-wave differential protection is then protected to the circuit breaker at these phase circuit two ends and sent out trip signal;

(7) obtain the three-phase current traveling-wave component i of each sampling instant by n transformer station test point place sampling _NA(t), i _NB(t), i _NC(t) with the three-phase current traveling-wave component i ' that predicts each sampling instant that obtains _NA(t), i ' _NB(t), i ' _NC(t) utilize conventional ratio braking characteristic to constitute traveling-wave differential protection, if the action of arbitrary phase current traveling-wave differential protection is then protected to the circuit breaker at these phase circuit two ends and sent out trip signal.

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