CN102013671A - Transient travelling wave amplitude integral type superspeed bus protection system and method thereof - Google Patents

Abstract

The invention relates to a transient travelling wave amplitude integral type superspeed bus protection system which has the advantages of simple structure, rapid detection speed, high sensitivity and the like and is convenient in use and a method thereof. The method is implemented as follows: installing N numbered protection units at the outlet of each outgoing line if a bus is connected with N numbered outgoing lines; realizing mutual communication between every two protection units via a signal bus; collecting the current and voltage signals of the line by each protection unit at a high speed, and independently judging the failure direction; if a certain protection unit judges that the line has a forward direction failure, sending out a lockout action message, transmitting the judgment result to other protection units by signal buses, receiving judgment results about respective line failure direction from other protection units, and comprehensively analyzing the judgment results of all protection units by each protection unit so as to determine the bus state; if all the protection units judge that the failure comes from the reverse direction, determining that the bus has a failure so as to promptly give out an instruction to trip off respective side switch to isolate the failed bus; and otherwise, determining that the bus has no failure and requires no isolation.

Description

Transient state travelling wave amplitude integration type ultrahigh speed bus protection system and method thereof

Technical field

The present invention relates to a kind of transient state travelling wave amplitude integration type ultrahigh speed bus protection system and method thereof.

Background technology

The substation bus bar of getting in touch various force devices such as power supply, transmission line and load is one of most important element of electric power system.If break down on the bus, bus protection must be excised all elements that connect on it fast.In case bus protection generation erroneous judgement behavior gently then causes losing a large amount of power or influencing device security, heavy then cause large-area power-cuts, even cause that the stable problem of system, its consequence may be catastrophic.Therefore bus protection scheme reasonable in design, the excellent protection algorithm of selection, all most important to reliability, selectivity and sensitivity and the responsiveness of bus protection.

Divide according to protection philosophy, bus protection mainly contains based on the protection of power frequency amount with based on transient based protection two big classes.Wherein power frequency amount current differential protection is present most widely used bus protection, but under the influence of various factors, mismatches and portion C T saturated etc. during fault externally as CT error, ratio, all might cause the misoperation of this type of protection.The introducing of ratio differential principle can solve the influence of above-mentioned factor, but it has also reduced the sensitivity of differential protection simultaneously.In order to eliminate the influence of fault transient process, all take filtering technique filtering fault high fdrequency component based on the protection of power frequency amount, and filtering certainly will prolong the Signal Processing process, the operate time of influence protection.Simultaneously, the element that is coupled on the substation bus bar is more, and this may further influence protection to the failure judgment time, so this principle protects general sensitivity lower, and operate time is longer.

In fact, fault transient process includes abundant fault message, if can therefrom extract fault signature exactly, then can realize the ultrahigh speed protection.Owing to generally before CT is saturated, already finish, so the saturated performance that can not influence protection of CT to failure judgment based on the protection of high frequency transient amount.Document [Ge Yaozhong; Dong Xingli; Dong Xinzhou; Deng. based on research (one) principle and the criterion [J] of the current traveling wave bus of wavelet analysis. the electrotechnics journal; 2003; 18 (2): 95-99.; Li Wei, Wang Qian, Du Yanhui. based on the distributed bus protection [J] of mathematical morphology transient state feature extraction. protecting electrical power system and control; 2009; 37 (2): 11-15.] proposed bus protection algorithm, and utilized wavelet transformation technique or Mathematical Morphology technology identification fault signature, but this type of algorithm only adopts transient current signal based on transient current; if little initial angle fault takes place, then its recognition methods is produced significant impact.Document [Duan Jiandong; Zhang Baohui; Zhang Shengxiang. utilize the distributed bus protection [J] of circuit transient state travelling wave power direction. Proceedings of the CSEE; 2004; 24 (6): 7-12.] proposed to utilize the distributed bus protection of circuit transient state travelling wave power direction; adopt wavelet transformation to extract the modulus maximum of capable ripple of initial voltage and current traveling wave; fault direction is determined in combination by the two; the differentiation result of comprehensive each element finally discerns the bus internal fault external fault, but this method does not still solve the problem that influences of little initial angle fault.

Summary of the invention

Purpose of the present invention provides a kind of simple in structure, easy to use exactly for addressing the above problem, and detection speed is fast, the transient state travelling wave amplitude integration type ultrahigh speed bus protection system and the method thereof of advantages such as sensitivity height.

For achieving the above object, the present invention adopts following technical scheme:

A kind of transient state travelling wave amplitude integration type ultrahigh speed bus protection system, this system is made up of distributed bus protection unit and signal bus.The outlet of N bar is arranged on the bus, then, N unit is installed altogether, can communicate by signal bus between each protected location at protected location of every outlet installing.Its workflow is as follows: each protected location is gathered the position signalling of electric current, voltage signal and the switch of this circuit, and each unit independently carries out the judgement of place line fault direction; If certain protected location determines this circuit generation positive direction fault, then send block action information and will differentiate the result by signal bus and pass to other protected location, receive other unit simultaneously to the differentiation result of line fault direction separately; The differentiation result of each all protected location of protected location analysis-by-synthesis, and then definite bus state; If the equal failure judgement of each protected location then draws bus and breaks down from the other direction, thereby send instruction tripping side switch separately immediately, fault bus is isolated; Otherwise bus does not break down, and need not isolate.

Described protected location is a kind of protective device, is installed in the exit of each bar circuit on the spot, can independently carry out the judgement of this line fault direction, and can control the switch of this circuit, and each protected location intercoms mutually through signal bus.

A kind of transient state travelling wave amplitude integration type ultrahigh speed bus bar protecting method, when utilizing busbar fault, detected initial transient state travelling wave all comes from the behind of circuit in all outlets, is direct wave; And during line fault, detected initial row ripple is a direct wave on all non-fault lines, but the characteristics that detected initial row ripple is a returning wave on the faulty line, ratio relation according to direct wave amplitude integration in each bar outlet in the special time after the fault and returning wave amplitude integration, identification busbar fault or line fault, and take appropriate measures.

The described identification bus whether foundation of fault is: when certain bar outlet forward fault, equal returning wave at the detected direct wave in the exit of this circuit and multiply by reflection coefficient; And during reverse fault, direct wave equals the refracted wave of dorsal part incident wave, and returning wave equals zero; When breaking down on the bus, can only detect direct wave in the exit of all circuits, and not have returning wave; For the forward fault, the amplitude of direct wave is less than the amplitude of returning wave; And for reverse fault, the amplitude of direct wave is much larger than the amplitude of returning wave, can judge whether fault of bus in view of the above.

The present invention proposes a kind of transient state travelling wave amplitude integration type ultrahigh speed bus protection technology.This technology is when utilizing busbar fault, and detected initial transient state travelling wave all comes from the behind of circuit in all outlets, is direct wave; And during line fault, detected initial row ripple is a direct wave on all non-fault lines, but detected initial row ripple is a returning wave on the faulty line.Ratio relation according to direct wave amplitude integration in each bar outlet in the special time after the fault and returning wave amplitude integration can identify busbar fault or line fault apace.By a typical substation bus bar has been carried out emulation, various fault conditions are set, verify the correctness and the validity of this bus protection principle with this.

Protection philosophy

1.1 the basic theories of fault traveling wave

Figure 1 shows that a simple substation bus bar, total n bar outlet is respectively l ₁To l _n, the wave impedance of circuit is Z _c

As circuit l ₁When upward certain some f1 place broke down, by superposition theory as can be known, any fault on the circuit was equivalent to the additional voltage source in the fault point, and consequent capable ripple is propagated from disturbance point road direction along the line both sides, and produces catadioptric at the discontinuous place of wave impedance.With protection test point R ₁Be starting point, any on the line 1 x place, transient voltage, electric current that can this point by wave equation be

$\mathrm{\Δu}=u^{+}(t-\frac{x}{v})+u^{-}(t+\frac{x}{v})---\left(1\right)$

$\mathrm{\Δi}=\frac{1}{Z_c}[u^{+}(t-\frac{x}{v})-u^{-}(t+\frac{x}{v})]---\left(2\right)$

In the formula Be the row velocity of wave propagation;

It is the wave impedance of circuit; L and C are the inductance and the electric capacity of unit length circuit; u ⁺And u ^-It is respectively the anti-capable ripple of propagating along the x positive direction that moves ahead ripple and propagate in the other direction along x.

Following formula shows on the circuit that arbitrarily transient current of any and voltage all are the stacks of ripple and anti-row ripple of moving ahead.From formula (1) with formula (2) can obtain direct wave and returning wave is respectively

u ⁺＝(Δu+z _cΔi)/2 (3)

u ^-＝(Δu-z _cΔi)/2 (4)

The row ripple runs into the wave impedance discontinuity point catadioptric can take place in communication process.Because the even distribution of transmission line parameter, the row ripple is general only to produce catadioptric in fault point and bus place.Studies have shown that at certain frequency band, as long as the bus stray capacitance is not equal to 0, no matter which kind of bus structure necessarily has: 0＜| k _f|≤1; And | k _z|＞0, k wherein _fAnd k _zBe respectively the row ripple on bus reflection and refraction coefficient [Zou Guibin, Gao Houlei, Jiang Shifang, Xu Bingyin. novel transient state travelling wave Amplitude Comparison ultrahigh speed direction protection [J]. Proceedings of the CSEE, 2009,29 (7): 84-90].

1.2 the signature analysis of forward and reverse capable ripple

With reference to figure 1, suppose that this system is the Monophase electric power system, the positive direction of definition line ripple is that bus points to circuit.For outlet l ₁, then the forward fault point is f1, the fault on the bus in fault or other outlet is its reverse fault.When the f1 point failure, the grid chart that the row ripple is propagated as shown in Figure 2.Suppose t ₀Be the moment that the initial row ripple arrives bus B, as can be seen from Figure 2, at l ₁The viewed transient state travelling wave signal in exit has two big classes: a class is a direct wave

Another kind of is returning wave

Wherein, d ₁Be circuit l ₁Length, d _MinIt is the shortest line length in other outlet.At [t ₀, t ₀+ 2d _Min/ v] in the time period, viewed all returning waves and all direct waves are respectively

$u^{-}=u_1^{-}+u_2^{-}+u_3^{-}+...---\left(5\right)$

$u^{+}={\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="HDA0000037741930000011.png,HDA0000037741930000031.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^{+}+u_2^{+}+u_3^{+}+...=k_f{u}^{-}---\left(6\right)$

Select time section [t why in the above-mentioned analysis ₀, t ₀+ 2d _Min/ v], be in order to guarantee at l ₁The exit only detects incident wave, the reflected wave that is studied in the circuit, prevents the influence of dorsal part circuit reflected wave.

If break down in other outlet as the f2 point, then the transmission network trrellis diagram of fault traveling wave as shown in Figure 3.At [t ₀, t ₀+ 2d ₁/ v] in the time period, circuit l ₁The exit can observe three class refracted waves, is respectively the initial row ripple that comes from the fault point

Refracted wave; Dorsal part opposite end bus reflected wave

Refracted wave; The fault point reflected wave Refracted wave.These refracted waves constitute l ₁The direct wave u in exit ⁺In the section, the exit does not have returning wave and occurs at this moment.Therefore forward, its value of returning wave are respectively

$u^{+}=u_1^{+}+u_2^{+}+u_3^{+}+...=k_z(\mathrm{\&Delta;}{u}_1^{+}+\mathrm{\&Delta;}{u}_2^{+}+\mathrm{\&Delta;}{u}_3^{+}...)---\left(7\right)$

u-＝0 (8)

Time period [t ₀, t ₀+ 2l ₁/ v] choose, be to guarantee at l ₁The exit only detects the refracted wave that comes from dorsal part circuit or bus, and is not studied the influence of opposite end bus reflected wave in the circuit.

If break down on the bus, for all outlets, then at time period [t as the f point ₀, t ₀+ 2d _Min/ v] in, can only observe initial direct wave in the exit of every circuit, and detect less than returning wave d herein _MinIt is the shortest Route Length in all outlets.

1.3 bus protection criterion

According to above-mentioned analysis, no matter be outlet fault or busbar fault, in certain period of time, it is as follows to get conclusion:

(1) when certain bar outlet forward fault, equals returning wave at the detected direct wave in the exit of this circuit and multiply by reflection coefficient; And during reverse fault, direct wave equals the refracted wave of dorsal part incident wave, and returning wave equals zero; This conclusion is adapted to any outlet.

(2) when breaking down on the bus, can only detect direct wave in the exit of all circuits, and not have returning wave.

(3) for the forward fault, the amplitude of direct wave is less than the amplitude of returning wave; And for reverse fault, the amplitude of direct wave is much larger than the amplitude of returning wave.

There are integrity problem in traveling-wave protection or transient based protection always, and its principal element is that the transient state travelling wave that is produced was very faint, only utilizes its reliability of initial row ripple information and sensitivity to reduce greatly when little initial angle fault took place.For avoiding this problem, this paper based on fault after in a period of time, the amplitude that aligns returning wave is respectively carried out integral operation, and constructs criterion according to the two magnitude relationship, makes full use of the transient state travelling wave energy of broad frequency band, improves the reliability of protection with this.For every outlet, the positive direction of definition line ripple is that bus points to by this circuit s ₁And s ₂Be the amplitude integration of direct wave and returning wave respectively, as follows

${\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="HDA0000037741930000011.png,HDA0000037741930000031.png"\; state="\{\{state\}\}">S</figure-callout>}}_1=\underset{t_0}{\overset{{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA0000037741930000032.png,HDA0000037741930000041.png"\; state="\{\{state\}\}">t</figure-callout>}}_0+\mathrm{\&tau;}}{\&Integral;}}\left|u^{+}\left(t\right)\right|\mathrm{dt}---\left(9\right)$

${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="HDA0000037741930000022.png,HDA0000037741930000031.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=\underset{t_0}{\overset{{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA0000037741930000032.png,HDA0000037741930000041.png"\; state="\{\{state\}\}">t</figure-callout>}}_0+\mathrm{\&tau;}}{\&Integral;}}\left|u^{-}\left(t\right)\right|\mathrm{dt}---\left(10\right)$

τ=min{2d in the formula _i/ v}, i=1 ... n.Be correct identification fault direction, the structure criterion is as follows

λ＝S ₁/S ₂(11)

If λ is less than the threshold value k of a setting ₀(0＜k ₀＜2), then differentiating this circuit positive direction breaks down; Otherwise fault occurs in the other direction; If the equal failure judgement of all circuits judges then that from the other direction bus breaks down.Above-mentioned analysis is based on the Monophase electric power system, for three-phase system, is the coupling between the elimination three-phase, The thesis Clark phase-model transformation technology, and extract the line mold component and analyze.

The invention has the beneficial effects as follows: when utilizing the outlet fault, the amplitude Characteristics of direction row ripple is different on non-fault line and the faulty line, and during busbar fault, the amplitude Characteristics of the direction row ripple in all outlets is identical, makes up identical criterion.Simulation and analysis shows that the fault detect speed of this principle bus protection is exceedingly fast, and has very high sensitivity and reliability.And protection philosophy is simple, more easily realizes.If can solve the extraction problem of voltage traveling wave, this method is expected to be applied in the actual power engineering.

Description of drawings

Fig. 1 is the substation bus bar structural representation;

Fig. 2 is a forward fault traveling wave grid chart;

Fig. 3 is the capable ripple grid chart of reverse fault;

Fig. 4 is distributed bus protection system configuration;

Fig. 5 is substation bus bar analogue system figure;

The detected direction row in each unit ripple when Fig. 6 is busbar fault;

The detected direction row in each unit ripple when Fig. 7 is the bus external fault;

Fig. 8 is each unit detected direction row ripple during for the little initial angle fault of outlet.

Embodiment

The present invention will be further described below in conjunction with accompanying drawing and case study on implementation.

System of the present invention constitutes as shown in Figure 4, and whole system is protected control unit on the spot by several, and (R1～Rn) and signal bus are formed.

The course of work of this distributed bus protection is as follows: suppose to have on bus N bar branch road (comprising outlet branch road, transformer branch road, bus connection switch etc.), then distributed bus protection is made up of n the protected location that is installed on this n bar branch road.The positional information of electric current, voltage signal and this branch switch of each this branch road of protected location high speed acquisition.Each unit independently carries out fault direction respectively and judges; determine this branch road generation positive direction fault as unit R 1; then send block action information and will differentiate the result by signal bus and pass to other unit; and receive the differentiation result of other unit to fault direction; the judged result of each all protected location of protected location analysis-by-synthesis, and then definite bus situation.When busbar fault, n the equal failure judgement of protected location is from the other direction, and analysis-by-synthesis draws bus and breaks down, and sends instruction tripping side switch separately immediately, and fault bus is isolated.

The transient state travelling wave amplitude integration type ultrahigh speed bus bar protecting method of being invented is when utilizing busbar fault, and detected initial transient state travelling wave all comes from the behind of circuit in all outlets, is direct wave; And during line fault, detected initial row ripple is a direct wave on all non-fault lines, but this difference that detected initial row ripple is a returning wave on the faulty line, ratio relation according to direct wave amplitude integration in each bar outlet in the setting-up time after the fault and returning wave amplitude integration, identification busbar fault or line fault, and take appropriate measures.

The described identification bus whether foundation of fault is: when certain bar outlet forward fault, equal returning wave at the detected direct wave in the exit of this circuit and multiply by reflection coefficient; And during reverse fault, direct wave equals the refracted wave of dorsal part incident wave, and returning wave equals zero; When breaking down on the bus, can only detect direct wave in the exit of all circuits, and not have returning wave; For the forward fault, the amplitude integration of direct wave is less than the amplitude integration of returning wave; And for reverse fault, the amplitude integration of direct wave is much larger than the amplitude integration of returning wave, can judge whether fault of bus in view of the above.

Simulation and analysis

Simulation model

Be the correctness of checking protection philosophy, utilize 230kV substation bus bar system of the PSCAD/EMTDC of simulation software structure, as shown in Figure 5.Transmission line adopts the frequency dependence model, and evenly transposition.Being studied bus is B, and each protected location R1, R2 and R3 are loaded on the exit of circuit, and regulation row ripple positive direction is pointed to this circuit for just with bus.Sample frequency is made as 100kHz.Can calculate outlet mould wave impedance by line parameter circuit value is 394.5 Ω, and line line velocity of wave propagation is v=2.922 * 10 ⁸M/s, threshold value is set at 1.5, and the amplitude of the forward and reverse capable ripple among the following simulation waveform figure is all taken from its absolute value.

Typical fault emulation

A. busbar fault.F1 point generation A phase earth fault on the bus is set,

Earth resistance is 50 Ω, and the fault initial angle is 60 °.Fig. 6 (a) and (b) and (c) shown R1, R2 and R3 place detected line mold component direct wave and returning wave oscillogram respectively.The amplitude integration size and the ratio thereof that can be obtained forward and reverse capable ripple by figure respectively are as shown in table 1.

Emulated data during table 1 busbar fault

By data in the table as can be known, the equal failure judgement direction of each protected location is in the other direction during busbar fault, analysis-by-synthesis, and bus breaks down as can be known, and it is correct to differentiate the result.

B. bus external fault.Circuit l is set ₂The AB phase-to phase fault takes place in last f2 point, and the fault point is apart from bus 90km.Fig. 7 (a) and (b) and (c) shown R1, R2 and R3 place detected line mold component direct wave and returning wave oscillogram respectively, table 2 has provided simulation result.

Emulated data during table 2 bus external fault

By Fig. 7 and table 2 as can be known, when the f2 point broke down outside the bus district, protected location R2 failure judgement direction was a forward, and the equal failure judgement direction of R1 and R3 is oppositely, and analysis-by-synthesis is the bus external area error as can be known, and judged result is correct.

Circuit l is set ₃B phase earth fault takes place in the f3 point of going up apart from bus 100km, and the fault initial angle is 10 °, to investigate the performance of bus protection.Fig. 8 (a) and (b) and (c) shown R1, R2 and R3 place detected line mold component direct wave and returning wave oscillogram respectively, table 3 has provided simulation result.

Simulation result during the little initial angle fault of table 3 outlet

By Fig. 8 and table 3 data as can be known, during little initial angle fault, the amplitude of forward and reverse capable ripple decreases, this is because the less institute of the instantaneous voltage of fault moment causes, simulation result conforms to fully with theory analysis, but the ratio of the two compares with threshold value, and sensitivity is still very high.

C. other influencing factor.In general, fault earthing resistance, abort situation, fault type etc. influence to some extent to the performance of traditional protection.For testing of the influence of above-mentioned factor to proposing criterion, carried out a series of emulation, it the results are shown in Table 4 and table 5.

Table 4 is when on the bus fault of different faults type and fault earthing resistance taking place, the amplitude integration of protected location R1, R2 and the detected forward and reverse capable ripple of R3 and ratio size, wherein R _fRepresent fault earthing resistance.By table 1 and table 4 emulated data as can be known, fault earthing resistance is big more, and the amplitude of direction row ripple is more little, but less to the ratios affect of the two, and it is worth much larger than threshold value.In addition, although the fault type difference, the direct wave amplitude of this moment is also much larger than the amplitude of returning wave.Therefore, fault type and fault resstance to the sensitivity of criterion almost without any influence.

The internal fault simulation result of table 4 different faults type and earth resistance

The simulation result of the external fault of table 5 different faults position and fault type

Table 5 has provided at circuit l ₂Simulation result during the external fault of last generation different faults position and fault type, D is meant the distance between fault point and the test point in the table 5.Data show in the table, and abort situation, fault type do not influence the correct decision of each protected location to fault direction, and criterion has sufficiently high sensitivity.

For simulation model shown in Figure 5, be connected with three outlets on the bus, generic line length is 155km, but the wave-wave speed calculated product split window time is τ=1.06m/s according to row.Each protected location carries out integral operation to direction row ripple, only is simple read group total, and is consuming time few.If add the propagation time of differentiation result on signal bus of each unit, export to final differentiation from detecting the initial row ripple, also can not surpass 2ms, so this principle protection speed is exceedingly fast.Little initial angle fault influences to some extent to the integrated value of direction row ripple, but little to its ratios affect, no matter bus internal fault or external fault, and protection all can correctly be judged.By emulated data as can be known, threshold value is set at 1.5, and, external area error interior for the district all has very high sensitivity.

Claims (3)

1. a transient state travelling wave amplitude integration type ultrahigh speed bus protection system is characterized in that, if be connected with the outlet of N bar on the bus, then in the exit of every outlet N protected location is installed on the spot; Intercom mutually by signal bus between the protected location; Electric current, the voltage signal of each this circuit of protected location high speed acquisition independently carry out the judgement of fault direction; If certain protected location determines this circuit generation positive direction fault, then send block action information and will differentiate the result by signal bus and pass to other protected locations, receive other unit simultaneously to the differentiation result of line fault direction separately, the differentiation result of each all protected location of protected location analysis-by-synthesis, and then definite bus state; If the equal failure judgement of each protected location, determines then that bus breaks down from the other direction, thereby send instruction tripping side switch separately immediately, fault bus is isolated; Otherwise bus does not break down, and need not isolate.

2. a transient state travelling wave amplitude integration type ultrahigh speed bus bar protecting method is characterized in that when utilizing busbar fault, detected initial transient state travelling wave all comes from the behind of circuit in all outlets, is direct wave; And during line fault, detected initial row ripple is a direct wave on all non-fault lines, but the characteristics that detected initial row ripple is a returning wave on the faulty line, ratio relation according to direct wave amplitude integration in each bar outlet in the special time after the fault and returning wave amplitude integration, identification busbar fault or line fault, and take appropriate measures.

3. transient state travelling wave amplitude integration type ultrahigh speed bus bar protecting method as claimed in claim 2, it is characterized in that, the described identification bus whether foundation of fault is: when certain bar outlet forward fault, equal returning wave at the detected direct wave in the exit of this circuit and multiply by reflection coefficient; And during reverse fault, direct wave equals the refracted wave of dorsal part incident wave, and returning wave equals zero; When breaking down on the bus, in the regular hour section, can only detect direct wave in the exit of all circuits, and not have returning wave; For the forward fault, the amplitude integration of direct wave is less than the amplitude integration of returning wave; And for reverse fault, the amplitude integration of direct wave is much larger than the amplitude integration of returning wave, can judge whether fault of bus in view of the above.

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