CN104808111B - Distribution line fault section location method based on energy function of releasing - Google Patents

Abstract

The invention discloses a kind of distribution line fault section location method based on energy function of releasing, for non-faulting section, its energy of releasing is kept approximately constant in normal operation and failure generating process, and numerical value is a minimum positive number；For fault section, energy function DC component of releasing variation tendency subtracts afterwards first to increase, and occurs to arc suppression coil to act in failure and reach maximum in output stabilization compensation current interval；Therefore fault section can determine whether according to increase multiple of the energy after failure generation of releasing, realizes fault location.The present invention occurs using failure and arc-extinction device acts the Wave data of overall process, avoid using zero-sequence current, can very well solve the problems, such as during the single-phase grounded malfunction in grounded system of low current of current generally existing that faint fault current, poor reliability, sensitivity are low, while system will not be introduced disturbing.

Description

Distribution line fault section location method based on energy function of releasing

Technical field

The present invention relates to distribution network line fault diagnostic method, specifically a kind of distribution line based on energy function of releasing Fault section location method.

Background technology

According to statistics, in the process of running, the power outage caused by Distribution Network Failure accounts for total power outage for power system More than 95%, wherein 70% accident is triggered by singlephase earth fault or bus-bar fault.And distribution neutral point is adopted extensively both at home and abroad With non-effective earthing (small current neutral grounding) mode, to avoid occurring causing power failure during singlephase earth fault.For distribution Singlephase earth fault, because fault characteristic value is faint, lacks reliable fault line selection and fault locating method always.As people are to matching somebody with somebody The raising of automation level requirement, more in the urgent need to fundamentally solving the fault-location problem of distribution.

The Fault Locating Method that current domestic and foreign scholars are proposed is roughly divided into two classes：One is injecting signal, and two is to be based on The section positioning of fault characteristic value.Injecting signal includes " S " injection method, alternating current-direct current synthesis injection method and parallel medium resistance method, Such method increases the interference to system, and can not detect instantaneity and intermittent grounding fault.Based on fault characteristic value Section positioning include zero mould electric current comparison method, section zero sequence admittance method, zero sequence reactive power direction method, based on difference of phase currents Positioning, residual method of addition, traveling wave method etc., such method existing characteristics amount obtains the keys such as difficulty, signal precise synchronization difficulty Sex chromosome mosaicism, and Part Methods reliability in high resistance ground is extremely low.

Current localization method have ignored the utilization to information before failure only using the data after failure generation.Meanwhile, Most of localization methods only consider zero-sequence current information (needing three phase informations), and high to transformer request, acquisition of information is complicated, and These methods will fail in the case of data phase shortage.

The content of the invention

It is an object of the invention to overcome above-mentioned the deficiencies in the prior art, it is proposed that a kind of matching somebody with somebody based on energy function of releasing Netting twine road fault section location method.

Principle of the invention：

In continuous-time domain, section Defining Instantaneous Power Components are

Δp_A(t)=p_1A(t)-p_2A(t)=u_1A(t)·i_1A(t)-u_2A(t)·i_2A(t)

In formula, u_kA(t)、i_kAT () is respectively test point k (k=1,2) place's failure phase phase voltage and phase current.Definition is released Energy function

In formula, T is a power frequency period (0.02s).

Make Δ u (t)=u_1A(t)+u_2A(t), Δ i (t)=i_1A(t)+i_2A(t), then

Δp_A(t)=u_2A(t)·Δi(t)+i_2A(t)·Δu(t)+Δu(t)·Δi(t) (1)

In formula, Section 3 is higher-order shear deformation relative to first two, negligible.

1) for non-faulting section (Fig. 1), Δ i (t) is section capacitive earth current.First two of analysis mode (1) below Size order.

The amplitude of section two ends difference between currentWherein b is the susceptance of circuit 1km, and the order of magnitude is about 10^-6.Therefore the order of magnitude of section two ends difference between current amplitude is about 10^-5(kA)。

Due to Load flow calculation pair as if three-phase symmetrical operation circuit, three-phase is reduced to a phase during analysis, because This part of theory is equally applicable to uniline.If U_2APhase angle be 0 °, section both end voltage difference can be according to Load flow calculation phase Theoretical calculation is closed to draw

In formula, S=P₂+jQ₂To flow through the trend of the A phases of test point 2, and there is P₂=| U_2A||I_2A| cos φ, Q₂=| U_2A| |I_2A| sin φ (φ is line power factor angle)；Z=R+jX is the complex impedance of section, and the order of magnitude is about 10⁰~10^-1.Section two Terminal voltage difference amplitude be

It can be seen that the order of magnitude of section both end voltage spread value is about 10^-1(kV)。

Analyzed according to more than, u_2A(t) Δ i (t) and i_2AT the order of magnitude of () Δ u (t) ratio is about 10^-2, Qian Zheke Ignore.Therefore, the section instantaneous power of non-faulting section can be reduced to

Δp_A(t)=i_2A(t)·Δu(t)

For small current neutral grounding system, due to non-zero-sequence current path, when there is singlephase earth fault, fault current is far small In load current, load current amplitude can be regarded as constant.According to formula (2), section both end voltage spread value is in normal operation and event It is kept approximately constant in barrier overall process.On the other hand, the phase angle tangent of segment voltage difference

There is θ<90 °-φ, if θ+ε=90 °-φ, because line impedance meets R<<X, From left side close to 1, therefore ε is a minimum angle more than zero.That is segment voltage difference is advancedAngle be 90 ° of-φ- ε.And becauseAdvanced phase currentAngle is φ, thereforeIn advanceSummarize conclusion, i.e. Δ u (t) Amplitude it is constant, phase angle is constant and advanced phase current i_2A(t)90°-ε。

If

Section instantaneous power is

Release energy function

It can be seen that, non-faulting section energy function of releasing is kept approximately constant in normal operation and failure generating process, and Numerical value is a minimum positive number.

2) for fault section (Fig. 2), the Section 2 of formula (4) derive and 1) in it is identical.Difference is section two ends Phase current difference is equal to section capacitance current and current in the fault point sum, i.e.,

Δ i (t)=Δ i_C(t)+i_f(t)≈i_f(t)

Can not ignore.

Faulted phase voltage u_2AT fundametal compoment is occupied an leading position in (), for ease of analysis, fundamental wave component is only considered below, Ignore the influence of harmonic wave and DC component.Then faulted phase voltage is represented by

Wherein U_2mT () ＞ 0 changes with time function for phase voltage fundamental voltage amplitude.

The electric current of trouble point is flowed through for system-wide capacitance current is multiplied by system off resonance degree v, is represented by

In formula, C_ΣIt is total system total ground capacitance, u₀T () is the residual voltage of the period system, negative sign represents failure electricity Stream is opposite with capacitance current flow direction.Because residual voltage is ahead of 90 ° of faulted phase voltage, residual voltage can be expressed as

Wherein U_0mT () >=0 is the function that residual voltage fundamental voltage amplitude is changed over time.Then

Section 1 is oscillating component in formula, and when energy function is released in calculating, oscillating component integrates in a cycle and is Zero.Therefore

If fault moment is t₁, arc suppression coil action after and output stabilization compensation electric current moment be t₂, as t ＜ t₁When, U_0mT ()=0, can obtain E_el(t)=0；Work as t₁+ T ＜ t ＜ t₂When, in integrating range, residual voltage and phase voltage amplitude are all higher than Zero, and v ≈ 1, then E_elT () is a positive number more than zero；As t ＞ t₂During+T, auto-tracing arc-eliminating coil is close to be fully compensated, V ≈ 0, E_el(t)≈0；[t₁,t₁+ T] and [t₂,t₂+ T] it is transition interval.I.e. for fault section, have

Therefore, occurred to arc suppression coil to act and E in output stabilization compensation current interval according to failure_elThe size of (t), i.e., Can determine that fault section.

Step of the invention：

Failure phase Defining Instantaneous Power Components are

P (n)=u (n) i (n)

Wherein, u (n) and i (n) is phase voltage and phase current sampling sequence.Section two ends test point 1,2 failure phases (A phases) Instantaneous power be respectively

p_1A(n)=u_1A(n)·i_1A(n)

p_2A(n)=u_2A(n)·i_2A(n)

According to fourier series formula, the energy function of releasing on Disgrete Time Domain is defined

N is a power frequency period data point, relevant with sample frequency.

Similarly, when normally running, energy function of releasing is defined as

In formula,Any one phase in desirable A, B, C three-phase. Respectively Phase voltage, current sampling data when normally being run for test point 1,2.

Technical solution of the invention is as follows：

A kind of distribution network line fault Section Location based on energy function of releasing, its feature is, methods described Comprise the following steps：

Step S1, according to the phase voltage current data that each test point is measured, calculates respectively releasing under normal operation Energy function E_el,normal；

Step S2, determines failure phase and fault moment t_f：After the generation of earth fault is detected, changed according to phase voltage Rule, selects failure mutually i.e. Earth Phase, is mutated the moment according to phase voltage or the arc-extinction device chugging moment determines fault moment t_f；

Step S3, firstly, since the maximum of energy function of releasing was appeared in the arc suppression coil not operating period, it is most Its maximum is measured to obtain, while reducing amount of calculation, automatic tracking and compensating arc distinction device operation time limit is being taken into full account (2~5 weeks Ripple) on the basis of choose detection means [t_f,t_f+ 0.04s] it is interval in common 2N point faulted phase voltage, phase current waveform data, Calculate the energy function E that respectively releases_elK (), k=0,1 ..., N, formula is as follows：

In formula：u_jA(n) and i_jAN () is the faulted phase voltage and faulted phase current sample sequence that test point j is measured, N is One power frequency period data point, k=0,1 ... j ... N, k represent ordered series of numbers subscript in a cycle；

Then, the energy function maximum E that releases is sought_el,max=max { E_el(k)}；

Step S4, according to releasing, energy increase multiple judges whether each section is fault section, i.e., the energy that ought release increase Multiple E_el,max/E_el,normal＞ K_set, then it is judged as fault section, on the contrary it is then non-faulting section, wherein, K_setIt is action threshold Value, is a positive number more than 1, and data reasonable set of its size according to acquisition system under normal circumstances typically takes 1~3；

Step S5, is distributed according to each test point, untill traversal is until finding out fault section.

Compared with prior art, the beneficial effects of the invention are as follows：To earth fault, by analyzing faulted phase current in failure There is preceding and failure and the phase current feature before acting occurs to arc suppression coil, therefrom extract fault characteristic value, and use overall process Waveform Euclidean distance positioned.Thus, it is only required to the faulted phase current of measurement circuitry, only considers that zero sequence (is needed before having broken Want three phase informations) tradition, data acquisition is simple, strong applicability；From from the point of view of signal synchronization, total system is used by GPS Synchronous Monitoring Data so that the difference between different test points is sensitiveer.The small electricity of current generally existing can very well be solved The problem that fault current is faint during stream single-phase grounded malfunction in grounded system, poor reliability, sensitivity are low, while will not draw to system Enter interference.

Brief description of the drawings

Fig. 1 is failure phase non-faulting section schematic diagram

Fig. 2 is failure phase fault section schematic diagram

Fig. 3 is distributed fault section positioning system structure figure

Fig. 4 is 10kV system emulation figures

Fig. 5 is failure and non-faulting is released energy function DC component curve

Specific embodiment

Fault waveform needed for the present invention comes from distributed fault section alignment system, and system architecture is as shown in Figure 3.Match somebody with somebody Electric network fault section alignment system is by master station, transformer station's (bus) measurement apparatus and is distributed in distribution line section everywhere Point failure positioner is constituted.Circuit is divided into some sections by fault location node in topology, three groups of each node installation Measurement apparatus, real-time synchronization collection circuit three-phase current and voltage.

According to the Fault Locating Method of invention, in 10kV power distribution network analogue systems, different types of failure is set.System 1., 2., 3. structure chart as shown in figure 4, be sector number, failure is arranged on section and 2. goes up.Sample frequency is 20kHz (each cycles Data point N=400), there is the moment for 0.5s in failure, arc-extinction device actuation time is set to 0.04s during earth fault, energy of releasing The threshold value of amount DC component increase multiple is set to 3.

Illustrated for the implementation method that fault section judges：

Step S1, according to the phase voltage current data that test point is measured, calculates under normal operation according to formula (5) 1., 2., the energy of releasing of 3. section, respectively 0.9912MJ, 1.0180MJ, 0.9920MJ；

Step S2, after system starts the generation for detecting earth fault according to residual voltage, measures A in bus three-phase voltage Mutually reduce, B, C phase are raised, and are defined as A phase faults；Determine that fault moment is 0.51s according to the phase voltage mutation moment；

Step S3, chooses totally 800 faulted phase voltages of point, phase current waveforms in measurement apparatus [0,51,0.55] interval Data (are designated as zero) under the data point for setting the failure generation moment, according to formula (4), calculate E_el(k), k=0,1 ..., N, and ask E_el,max=max { E_el(k) }, as a result as shown in table 1；

Table 1 is singlephase earth fault simulation result

Wherein, fault section and non-faulting energy function curve of releasing are as shown in Figure 5 during 500 Ω earth resistances.

Step S4, section 2. release energy increase multipleIt is judged as its fault section, conversely, 1., 3. section is non-faulting section.

Claims (3)

1. a kind of distribution network line fault Section Location based on energy function of releasing, it is characterised in that methods described bag Include following steps：

Step S1, according to the phase voltage current data that each test point is measured, calculates the energy of respectively releasing under normal operation Function DC component E_el,normal；

Step S2, determines failure phase and fault moment t_f；

Step S3, first, chooses detection means [t_f,t_f+ 0.04s] it is interval in common 2N point faulted phase voltage, phase current waveform Data, calculate the energy function E that respectively releases_elK (), k=0,1 ..., N, formula is as follows：

$E_{el}\left(k\right)=\underset{n=k}{\overset{k+N-1}{\&Sigma;}}\&lsqb;u_{1A}\left(n\right)\&CenterDot;i_{1A}\left(n\right)-u_{2A}\left(n\right)\&CenterDot;i_{2A}\left(n\right)\&rsqb;$

In formula：u_jA(n) and i_jAN () is the faulted phase voltage and faulted phase current sample sequence that test point j is measured, N is one Power frequency period data point, k=0,1 ... j ... N, k represent ordered series of numbers subscript in a cycle；

Then, the energy function maximum E that releases is sought_el,max=max { E_el(k)}；

Step S4, according to releasing, energy increase multiple judges whether each section is fault section, i.e., the energy that ought release increase multiple E_el,max/E_el,normal＞ K_set, then it is judged as fault section, otherwise be then non-faulting section；

Step S5, is distributed according to each test point, untill traversal is until finding out fault section.

2. the distribution network line fault Section Location based on energy function of releasing according to claim 1, its feature It is that the step S2 includes：

After the generation of earth fault is detected, according to phase voltage Changing Pattern, failure mutually i.e. Earth Phase is selected, according to phase voltage Mutation moment or arc-extinction device chugging moment determine fault moment t_f。

3. the distribution network line fault Section Location based on energy function of releasing according to claim 1, its feature It is K in the step S4_setIt is the artificial action threshold value for setting, takes 1~3.