CN100334458C - Malfunction route selection method for resonant grounded system based on current decomposition and wattles detection - Google Patents

Abstract

The present invention relates to a fault selecting method of a resonance grounding system, which is based on current decomposition and reactive power detection, and belongs to the field of protection technology of an electric power system. The method comprises the steps that zero sequence voltage and transient current components without power frequency quantity are obtained through a digital wave trap from the zero sequence voltage and zero sequence currents which are collected; then, the zero sequence voltage is orthogonally decomposed by the transient zero sequence currents to obtain transient reactive power of a line; a self-adaptive method for selecting the fault line is formed according to the principle that the difference between sum of the transient reactive power of all normal lines and the transient reactive power of the fault line is a minimum value. The method of the present invention can overcome the influence of load, unbalanced currents of the system, electric arc and noise interference, and when a short line has a fault, the method can overcome the influence of capacitance currents of normal long lines, have no need of setting and no reference to the judgment of polarity and direction, and have self-adaptability. A great amount of digital simulation results show that the method has good effects.

Description

Malfunction route selection method for resonant grounded system based on Current Decomposition and idle detection

Technical field:

The present invention relates to a kind of malfunction route selection method for resonant grounded system, belong to the protecting electrical power system technical field based on Current Decomposition and idle detection.

Background technology:

Research, test and operation show; why difficult the detection of the singlephase earth fault of resonance grounding electrical network is with protection; its main cause is the little and earth point electric arc instability of fault current, and the steady-state current that flows through faulty line is very faint, and difficulty accurately detects and adjust.Last century, the mid-80 was to the nineties, and microcomputer line selection apparatus application development is very fast, but low ebb appears again in the application in nearly ten years, and this also illustrates route selection the complex nature of the problem.Yet, during resonance grounding electrical network generation singlephase earth fault, fault phase capacitor discharge and the charging of non-fault phase electric capacity produce the amplitude transient current bigger several times to tens times than steady-state value, utilize transient current to carry out failure line selection, have highly sensitive, be subjected to arc suppression coil to influence advantages such as little.In recent years, people's special concern utilized the low current grounding resist technology (list of references 1-14) of transient signal.

The resonance grounding electrical network, fault current distributes as shown in Figure 1.The zero sequence transient current of fault feeder is formed (list of references 15) by the capacitive transient current (actual is the general name of capacitive stable state, capacitive attenuate high frequency and capacitive decaying dc) of the non-fault phase of whole non-fault feeders and the transient state inductive current (actual is the general name of perceptual stable state power frequency, perceptual decaying dc) of arc suppression coil.When earth fault occur in phase voltage through null value near, the transient state inductive current reaches maximal value, formed the loop and do not flow through non-fault line by faulty line and arc suppression coil, perceptual attenuating dc component wherein is more clear, and the high frequency transient component of fault phase is very little.In the time of near earth fault occurs in the phase voltage maximal value, the transient state inductive current is close to 0, and transient state capacitance current maximum forms loop (list of references 15) by non-fault line and faulty line.According to the characteristics of zero sequence transient current, can form the route selection criterion through effective processing.Emergency protection that list of references 6 is developed and detection system on to the low-current ground fault line selection Study on Technology of utilizing transient signal, have obtained important breakthrough.But be based on the method for polarity and direction, in transform at the unclear old station of CT polarity, use and inconvenience, on-the-spot not satisfied.

List of references:

[1] Tang Yi, Chen Kui, Chen Qing, etc. the absolute value of admittance mutual deviation and the research of maximum value method small current earthing wire-selecting. Proceedings of the CSEE, 2005,25 (6): 49～54.

[2] Miao Youzhong, Sun Yaming, Yang Hua. the transient current protection new principle of isolated neutral distribution system feeder line singlephase earth fault. Proceedings of the CSEE, 2004,24 (2): 28～32.

[3] Xue Yongduan, Xu Bingyin, Feng Zuren. the idle and instantaneous reactive power definition based on the non-sinusoidal circuit of Hilbert conversion. Automation of Electric Systems, 2004,28 (12): 35～39.

[4] Sun Yaming, Yan Bin. based on the singlephase earth fault new location method of non-fault phase transient current. electric power network technique, 2004,28 (19): 55～59.

[5] Xue Yongduan, Feng Zuren, Xu Bingyin etc. based on transient zero-sequence current small current earthing wire-selecting research relatively. Automation of Electric Systems, 2003,28 (7): 48～53.

[6] Xue Yongduan, Chen Yu, Xu Bingyin etc. utilize the novel low current grounding detection system of transient state feature. Automation of Electric Systems, 2004,28 (24): 83～87.

[7] Sun Yaming, Miao Youzhong. the transient current protection new principle of resonance grounding distribution system feeder line singlephase earth fault. Proceedings of the CSEE, 2004,24 (3): 62～66.

[8] Lian Hongbo, Yang Yihan, Pan Yonggang, Tan Weipu. in the small current neutral grounding system towards the reclosing technology of singlephase earth fault. Automation of Electric Systems, 2004,28 (6): 73-77.

[9] Zhu Dan, Jia Yajun, Cai Xu. the route selection of transient state energy method principle. Electric Power Automation Equipment, 2004,24 (3): 75～78.

[10] Zhu Dan, Cai Xu. low current neutral grounding electric network improves energy method earthing wire-selecting principle. relay, 2004,32 (10): 44～48.

[11] in of the modification scheme analysis of upright great waves .35kV power network neutral point through low resistance grounding. Automation of Electric Systems, 2004,32 (16): 57～59.

[12] Suo Nanjiale, Zhang Chao, Wang Shugang. based on the low-current ground fault line selection research of model parameter method of identification. Automation of Electric Systems, 2004,28 (19): 65～70.

[13] Cai Xu. based on the synthesis increment method one-phase ground protection of magnetic bias arc suppression coil. Automation of Electric Systems, 2003,27 (20): 68～72.

[14] Chen Zhongren, Wu Weining, Chen Jiahong. the measuring and tracing of power distribution network automatic arc-suppressing device. Automation of Electric Systems, 2004,28 (10): 84～87.

[15] He Jiali, Song Congju. Power System Relay Protection (enlarged edition). Beijing: China Electric Power Publishing House, 2004.

[16] section roc, Sun Yukun, Yin Pengjun etc. single-phase circuit Current Decomposition and power definition new method. current system robotization, 2005,29 (5): 34-37.

Summary of the invention:

The present invention is based on the quadrature decomposition computation transient state reactive power of electric current, utilize the principle that approximately equates on all non-fault line transient state reactive power sums and the faulty line transient state reactive power numerical value, propose new failure line selection adaptive approach.

Method of the present invention obtains the transient state component (not comprising the power frequency amount) of residual voltage, electric current at first with the residual voltage that collects and the zero-sequence current digital trap by a 50Hz; Then transient zero-sequence current is carried out quadrature to residual voltage and decompose, obtain the transient state reactive power of circuit; Next perfect the principle that obtains minimum value after the difference of circuit transient state reactive power sum and faulty line transient state reactive power, the adaptive approach of structure failure line selection according to all.

The quadrature of 1 current signal decomposes and idle detection

The definition of reactive power has a variety of, and the present invention uses transient state zero-sequence fault electric current and transient state zero-sequence fault voltage to carry out the decomposition of electric current quadrature, obtains reactive power.If the voltage u at circuit two ends (ω t), current i (ω t) they all are the periodic signals of random waveform, its cycle is T, generally all satisfies the Di Liheli condition, then can carry out fourier decomposition to it, respectively suc as formula shown in (1) and the formula (2):

$u\left(\mathrm{\ωt}\right)=a_{u0}+\underset{k=0}{\overset{\∞}{\mathrm{\Σ}}}{a}_{\mathrm{uk}}(\cos \mathrm{k\ωt}+b_{\mathrm{uk}}\sin \mathrm{k\ωt})---\left(1\right)$

In the formula:  is the phase differential of voltage and electric current.If n=max (k, l), definition 2n+1 dimension function space V:

V＝span(A)＝span[1，cosωt，sinωt，...，cos?nωt，sin?nωt] ^T (3)

V is a linear space.If x ∈ is V, y ∈ V, the definition inner product:

$(x,y)={\∫}_0^{\mathrm{\ωt}}x\·\mathrm{yd\ωt}---\left(4\right)$

The linear space V that has defined inner product can be called Euclidean space (Euc1id space), and vectorial A is one group of base of Euclidean space.According to the linear space theory, can ask one group of orthogonal basis of Euclidean space V with Schmidt (Schmidt) orthogonal method:

B＝[β ₀，β ₁，...，β _2n-1，β _2n] ^T (5)

In the formula: β ₀=u (ω t).

Because B is the orthogonal basis of Euclidean space V, so and the equal pairwise orthogonal of each component of the arbitrary vector in the SPACE V of its linear expression.According to the character of orthogonal vector, the inner product of any two elements is 0 among the orthogonal basis B.If the coordinate of current i (ω t) under orthogonal basis B is:

K _Bi＝[m ₀，m ₁，...，m _2n-1，m _2n] (6)

Each element in the coordinate can be tried to achieve by formula (12):

$m_h=\frac{{\∫}_0^{\mathrm{\ωT}}i\left(\mathrm{\ωt}\right)\·{\mathrm{\β}}_h\left(\mathrm{\ωt}\right)\mathrm{d\ωt}}{{\∫}_0^{\mathrm{\ωT}}{\mathrm{\β}}_h^2\left(\mathrm{\ωt}\right)\mathrm{d\ωt}},h=\mathrm{0,1},...,2n---\left(7\right)$

(ω t) is expressed as under orthogonal basis B with current i:

i(ωt)＝m ₀·u(ωt)+m ₁·β ₁+m ₂·β ₂+...+m _2n·β _2n (8)

Definition:

i _b＝m ₀·u(ωt) (9)

i _h＝m ₁·β ₁+m ₂·β ₂+...+m _2n·β _2n (10)

Because m ₀Be real number, so i _bIdentical with the waveform shape of u (ω t), phase place is identical, and amplitude differs m ₀Doubly.So definition resistive current component i _bBe active current component i _pExpression; And i _hIn each component all with voltage u (ω t) quadrature, so the definition and the current component i of voltage u (ω t) quadrature _hFor the reactive current component, use i _qExpression.

As follows to above-mentioned Current Decomposition with the definition brief summary:

i _p＝i _b＝m ₀·u(ωt) (11a)

i _q＝i _h＝m ₁·β ₁+m ₂·β ₂+...+m _2n·β _2n (11b)

i(ωt)＝i _p+i _q＝i _b+i _h (11c)

Instantaneous useful power p in the circuit and instantaneous reactance capacity q are defined as:

p＝u(ωt)·i _p＝m ₀·u ²(ωt) (12a)

q＝u(ωt)·i _q＝u(ωt)·(m ₁·β ₁+m ₂·β ₂+...+m _2n·β _2n)(12b)

The active power of circuit and reactive power are defined as the effective value of instantaneous power:

$P=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}\mathrm{pd\ωt}=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}{m}_0{u}^2\left(\mathrm{\ωt}\right)\mathrm{d\ωt}---\left(13a\right)$

$Q=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}\mathrm{qd\ωt}=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}{i}_{q}u\left(\mathrm{\ωt}\right)\mathrm{d\ωt}---\left(13b\right)$

Can prove that the power definition in the instantaneous effective value of active power that the present invention uses and reactive power definition and the traditional sinusoidal current Power Theory is unified.

2 failure line selection principle and methods

In the resonance grounding electrical network, the size of high frequency transient component and fault switching angle are closely related.When fault occurs in phase voltage and approaches near the maximal value, the transient state capacitance current is a lot of greatly than the transient state inductive current, the high frequency transient electric current of grounding through arc of flowing through is very little, and detected reactive power mainly is to perfect the reactive power sum that the circuit equivalent capacity absorbs on faulty line.Therefore all perfect the difference of circuit transient state reactive power sum and faulty line transient state reactive power, are smaller values.When mistake was thought faulty line with a non-fault line, the difference of its transient state reactive power and other circuit transient state reactive power sum can be a bigger value.Take this, can form the route selection criterion, express by formula (14):

$\mathrm{\Δ}{Q}_i=\left|\underset{\underset{j\≠1}{j=1}}{\overset{n}{\mathrm{\Σ}}}\right|Q_j|-|Q_i\left|\right|,i=\mathrm{1,2},...,n---\left(14a\right)$

Wherein, n is the outlet sum.Fault outlet L _fSatisfy:

ΔQ _f＝min{ΔQ _i}，i＝1，2，...，n (14b)

When fault occurs in the glitch angle situation of phase voltage zero cross near, transient state zero-sequence fault electric current mainly is perceptual weight, path be by earth point through faulty line and arc suppression coil to ground, under this situation, the attenuating dc component of faulty line is comparatively obvious, and the attenuating dc component on the non-fault line is almost 0.At this moment, therefore the transient state reactive power on the faulty line will can carry out following processing: find out the transient state reactive power of three maximums in each circuit, and series arrangement is Q by size much larger than the transient state reactive power of other non-fault line _j, Q _k, Q _m,, promptly satisfy if the transient state reactive power of faulty line is far longer than the transient state reactive power of non-fault line

|Q _j|＞K _q(|Q _k|+|Q _m|) (15)

Then circuit j is a faulty line.In the formula (15), K _qBe a coefficient, value 10.

This method performing step is as follows:

(1) starts fault line selection device: use bus residual voltage instantaneous value u respectively _n(t) greater than K _U1U _n, bus residual voltage sudden change amount is greater than K _U2U _n, in two cycles bus residual voltage power frequency quantitative changeization greater than K _U3U _nThree kinds of algorithms finish the startup of fault line selection device, K in three kinds of algorithms _U1Value is 0.35, K _U2Value is 0.1, K _U3Value is 0.1, U _nExpression bus rated voltage; After fault line selection device starts, each output line and the bus zero-sequence current and the bus residual voltage of 5 cycles after preceding 2 cycles of fault and the fault under the immediate record;

(2) the bus residual voltage to noting utilizes the sudden change amount to detect principle and determines singlephase earth fault generation t constantly _f

(3) calculate the transient state component of each circuit zero-sequence current: the improvement fourier algorithm that use can the filtering attenuating dc component calculates the fundametal compoment i of the 3rd cycle zero-sequence current after the fault _0b(t), the zero-sequence current after the fault deducts i _0b(t) just obtain the transient state component of zero-sequence current, it comprises high frequency transient component and attenuating dc component;

(4) use formula $Q=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}\mathrm{qd\ωt}=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}{i}_{q}u\left(\mathrm{\ωt}\right)\mathrm{d\ωt}$ Calculate the size of the reactive power Q of each circuit zero sequence fault current formation;

(5) first three is maximum to select these reactive power Qs, and series arrangement is Q by size _j, Q _k, Q _m, according to formula | Q _j|＞K _q(| Q _k|+| Q _m|) carry out fault distinguishing, K in the formula _qValue 10; If satisfy this formula, then circuit j is a faulty line; Do not satisfy this formula and then further calculate Q _jWhether greater than Q _k, Q _mAnd, if not, circuit L then is described _j, L _k, L _mOn reactive power be more or less the same, then be bus-bar fault, if then transfer differentiation to the line that is out of order;

(6) utilize formula $\mathrm{\Δ}{Q}_i=\left|\underset{\underset{j\≠1}{j=1}}{\overset{n}{\mathrm{\Σ}}}\right|Q_j|-|Q_i\left|\right|,$ I=1,2 ..., n calculates the Δ Q of each circuit _i, utilize Δ Q _f=min{ Δ Q _i, i=1,2 ..., n, the circuit of selecting the minimum value place is faulty line.

Method of the present invention has the influence that can overcome load, system's out-of-balance current, electric arc, noise, and when the short-term fault, this method can overcome the influence of sound long line capacitance electric current, need not adjust, do not relate to the judgement of polarity and direction, have adaptivity.A large amount of Digital Simulation results show that this method has effect preferably.

Description of drawings:

Fig. 1 is the distribution of current during single-phase earthing in the arc suppression coil earthing electric network.

Fig. 2 is the failure line selection process flow diagram.

Embodiment:

This method is the residual voltage that collects and the zero-sequence current digital trap by a 50Hz, obtains residual voltage, and do not comprise the transient state component of the electric current of power frequency amount; Then transient zero-sequence current is carried out quadrature to residual voltage and decompose, obtain the transient state reactive power of circuit; Perfect the principle that obtains minimum value after the difference of circuit transient state reactive power sum and faulty line transient state reactive power, the adaptive approach of structure failure line selection according to all again; This method performing step is as follows:

(1) starts fault line selection device: use bus residual voltage instantaneous value u respectively _n(t) greater than K _U1U _n, bus residual voltage sudden change amount is greater than K _U2U _n, in two cycles bus residual voltage power frequency quantitative changeization greater than K _U3U _nThree kinds of algorithms finish the startup of fault line selection device, K in three kinds of algorithms _U1Value is 0.35, K _U2Value is 0.1, K _U3Value is 0.1, U _nExpression bus rated voltage; After fault line selection device starts, each output line and the bus zero-sequence current and the bus residual voltage of 5 cycles after preceding 2 cycles of fault and the fault under the immediate record;

(2) the bus residual voltage to noting utilizes the sudden change amount to detect principle and determines singlephase earth fault generation t constantly _f

(3) calculate the transient state component of each circuit zero-sequence current: the improvement fourier algorithm that use can the filtering attenuating dc component calculates the fundametal compoment i of the 3rd cycle zero-sequence current after the fault _0b(t), the zero-sequence current after the fault deducts i _0b(t) just obtain the transient state component of zero-sequence current, it comprises high frequency transient component and attenuating dc component;

(4) use formula $Q=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}\mathrm{qd\ωt}=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}{i}_{q}u\left(\mathrm{\ωt}\right)\mathrm{d\ωt}$ Calculate the size of the reactive power Q of each circuit zero sequence fault current formation;

(5) first three is maximum to select these reactive power Qs, and series arrangement is Q by size _j, Q _k, Q _m, according to formula | Q _j|＞K _q(| Q _k|+| Q _m|) carry out fault distinguishing, K in the formula _qValue 10; If satisfy this formula, then circuit j is a faulty line; Do not satisfy this formula and then further calculate Q _jWhether greater than Q _k, Q _mAnd, if not, circuit L then is described _j, L _k, L _mOn reactive power be more or less the same, then be bus-bar fault, if then transfer differentiation to the line that is out of order;

(6) utilize formula $\mathrm{\Δ}{Q}_i=\left|\underset{\underset{j\≠1}{j=1}}{\overset{n}{\mathrm{\Σ}}}\right|Q_j|-|Q_i\left|\right|,$ I=1,2 ..., n calculates the Δ Q of each circuit _i, utilize Δ Q _f=min{ Δ Q _i, i=1,2 ..., n, the circuit of selecting the minimum value place is faulty line.

The inventor adopts said method to implement in a plurality of units, and a large amount of Digital Simulation results show that this method has effect preferably.

Claims (1)

1. malfunction route selection method for resonant grounded system based on Current Decomposition and idle detection, it is characterized in that this method with the residual voltage that collects and zero-sequence current digital trap, obtain residual voltage, and do not comprise the transient state component of the electric current of power frequency amount by a 50Hz; Then transient zero-sequence current is carried out quadrature to residual voltage and decompose, obtain the transient state reactive power of circuit; Perfect the principle that obtains minimum value after the difference of circuit transient state reactive power sum and faulty line transient state reactive power, the adaptive approach of structure failure line selection according to all again; This method performing step is as follows:

(1) starts fault line selection device: use bus residual voltage instantaneous value u respectively _n(t) greater than K _U1U _n, bus residual voltage sudden change amount is greater than K _U2U _n, in two cycles bus residual voltage power frequency quantitative changeization greater than K _U3U _nThree kinds of algorithms finish the startup of fault line selection device, K in three kinds of algorithms _U1Value is 0.35, K _U2Value is 0.1, K _U3Value is 0.1, U _nExpression bus rated voltage: after fault line selection device starts, each output line and the bus zero-sequence current and the bus residual voltage of 5 cycles after preceding 2 cycles of fault and the fault under the immediate record;

(2) the bus residual voltage to noting utilizes the sudden change amount to detect principle and determines singlephase earth fault generation t constantly _f

(3) calculate the transient state component of each circuit zero-sequence current: the improvement fourier algorithm that use can the filtering attenuating dc component calculates the fundametal compoment i of the 3rd cycle zero-sequence current after the fault _0b(t), the zero-sequence current after the fault deducts i _0b(t) just obtain the transient state component of zero-sequence current, it comprises high frequency transient component and attenuating dc component;

(4) use formula $Q=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}\mathrm{qd\ωt}=\frac{1}{\mathrm{\ωT}}{\∫}_0^{\mathrm{\ωT}}{i}_{q}u\left(\mathrm{\ωt}\right)\mathrm{d\ωt}$ Calculate the size of the reactive power Q of each circuit zero sequence fault current formation;

(5) first three is maximum to select these reactive power Qs, and series arrangement is Q by size _j, Q _k, Q _m, according to formula | Q _j|＞K _q(| Q _k|+| Q _m|) carry out fault distinguishing, K in the formula _qValue 10: if satisfy this formula, then circuit j is a faulty line; Do not satisfy this formula and then further calculate Q _jWhether greater than Q _k, Q _mAnd, if not, circuit L then is described _j, L _k, L _mOn reactive power be more or less the same, then be bus-bar fault, if then transfer differentiation to the line that is out of order;

(6) utilize formula ${\mathrm{\ΔQ}}_i=\left|\underset{\underset{j\≠i}{j=1}}{\overset{n}{\mathrm{\Σ}}}\right|Q_j|-|Q_i\left|\right|,$ I=1,2 ..., n calculates the Δ Q of each circuit _i, utilize Δ Q _f=min{ Δ Q _i), i=1,2 ..., n, the circuit of selecting the minimum value place is faulty line.

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