CN104267310A - Voltage dip source positioning method based on disturbance power direction - Google Patents

Abstract

The invention provides a voltage dip source positioning method based on the disturbance power direction and belongs to automatic monitoring methods for power grid voltage dip source positioning. The method is characterized in that under the effect that a disturbance voltage in a power grid fault process is obtained according to the superposition principle of linear circuits, the direction of an active disturbance power flow is used for accurately positioning a voltage dip source; when active disturbance power is positive, a disturbance source is located at the upstream portion of a monitoring point; when the active disturbance power is negative, the disturbance source is located at the downstream portion of the monitoring point; an algorithm of the corresponding disturbance power is given. The voltage dip source positioning method can be used for certainly positioning voltage dips caused by various power grid faults, is suitable for radiation type or ring type or single-circuit type or two-circuit type or single-power-supply type or multi-power-supply type grid structure power grids, and is also suitable for voltage dip source positioning caused by capacitor switching, transformer switching and large motor starting disturbance; according to the voltage dip source positioning method, the voltage and current of the monitoring point need to be sampled synchronously.

Description

A kind of voltage sag source localization method based on power of disturbance direction

Technical field

The present invention relates to the automatic monitoring method that source electricity falls in a kind of line voltage temporarily, particularly a kind of voltage sag source localization method based on power of disturbance direction.

Background technology

Voltage dip, refers to that supply voltage root-mean-square value drops to suddenly 90% ~ 10% of rated voltage amplitude in the short time, and its Typical duration is a kind of phenomenon of 10ms ~ 1min.Some increasingly automated equipment are easy to the impact being subject to voltage dip, the voltage dip in several cycle all can cause tremendous economic to lose to commercial production, according to state's external survey, in power quality problem, voltage dip has become main complaint reason, even accounts for and complains 80% of proportion.But electric energy a kind of to be provided to power consumer by power department, and by the specialities for, electricity consumption both sides common guarantee quality.In the responsibility declined causing the quality of power supply, often difference being existed to the judgement of quality of power supply decrease reason be even absorbed in economic dispute because lack for electricity consumption both sides.To voltage sag source diagnosis, location, can define for electricity consumption both sides responsibility, also provide reference and foundation for formulating mitigate policies, for this reason, falling the concern that source electricity causes domestic and international researcher in recent years temporarily.

Voltage dip source electricity, determines to cause the disturbing source of voltage dip to be positioned at which side of monitoring device exactly.Existingly fall source electricity method temporarily mainly from external researcher, domestic research is comprehensive to the com-parison and analysis of the localization method of foreign study and summary or existing localization method mostly, the rarely seen proposition having new definition method.Divide from positioning principle and be broadly divided into following two classes.The first kind has: one utilizes disturbance energy and power of disturbance initial spike localization method, and the second is that this method is improved the disturbance source locating being generalized to injected system energy, and the third introduces disturbance reactive power and quadergy, makes the method obtain expansion.These class methods are when disturbance energy and power of disturbance misfit, and confidence level reduces greatly, and unreliable to ground connection property localization of fault.Equations of The Second Kind can be summarized as the method based on impedance, the method for decision-making system track slope and electric current real part polarity, is comparatively applicable to symmetric fault location.The impact that the method for equiva lent impedance real part polarity is selected by inaction interval is larger.Distance impedance relay method is applicable to bilateral source electric power system.The voltage dip locating accuracy that these localization methods cause symmetrical fault is higher, and lower to the accuracy rate of the voltage dip location that asymmetric fault causes, and, be only applicable to the emanant electrical network of single loop.

Summary of the invention

The object of the invention is for Problems existing in prior art, a kind of voltage sag source localization method based on power of disturbance direction is provided, realize the automatic monitoring of line voltage being fallen temporarily to source, be applied to analytical instrument and the automated watch-keeping facility of various electrical network pollution sources of electrical energy quality.

Realize the technical scheme of the object of the invention: the present invention, according to the superposition principle of linear circuit, obtains in electric network fault process under the effect of disturbance voltage, falls source temporarily with the accurate positioning voltage in direction of disturbance active power stream; Disturbance active power is timing, and disturbing source is in the upstream of monitoring point; Disturbance active power is for time negative, and disturbing source is in the downstream of monitoring point;

Concrete steps are as follows:

Step a. establishes phaselocked loop, when electrical network normally runs, before namely voltage dip occurs, in monitoring point to three-phase voltage and electric current respectively with the N number of point of per primitive period synchronized sampling: u _ami(n), u _bmi(n), u _cmi(n) and i _ami(n), i _bmi(n), i _cmi(n); Centering point useful earthing electric network, is calculated the root-mean-square value of each phase-to-ground voltage by formula (1); Centering point non-useful earthing electric network, is calculated the root-mean-square value of each relative neutral point of electric network voltage by formula (2); When the root-mean-square value of any phase voltage is less than the specified phase voltage of 90%, voltage Sag Disturbance occurs;

$\left\{\begin{array}{c}{U}_{\mathrm{ami}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{ami}}\left(n\right)\right]}^2}\\ U_{\mathrm{bmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{bmi}}\left(n\right)\right]}^2}\\ U_{\mathrm{cmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{cmi}}\left(n\right)\right]}^2}\end{array}\right.---\left(1\right)$

$\left\{\begin{array}{c}{U}_{\mathrm{ami}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{ami}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\\ U_{\mathrm{bmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{bmi}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\\ U_{\mathrm{cmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{cmi}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\end{array}\right.---\left(2\right)$

In formula, U _ami, U _bmi, U _cmithe three-phase voltage u that monitoring point mi records respectively _ami(n), u _bmi(n), u _cmithe root-mean-square value of (n), $u_{\mathrm{mi}}^0\left(n\right)=[u_{\mathrm{ami}}\left(n\right)+u_{\mathrm{bmi}}\left(n\right)+u_{\mathrm{cmi}}\left(n\right)]/3$ It is the residual voltage of electrical network;

Voltage dip pushes away forward KN sampled point, gets voltage Sag Disturbance three-phase electric current and voltage sampled value: u after occurring _apmi(n-KN), u _bpmi(n-KN), u _cpmiand i (n-KN) _apmi(n-KN), i _bpmi(n-KN), i _cpmi(n-KN) three-phase voltage, and continuation is sampled during disturbance, electric current obtain: u _admi(n), u _bdmi(n), u _cdmi(n) and i _admi(n), i _bdmi(n), i _cdmi(n), try to achieve disturbance voltage and current:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right)=u_{\mathrm{admi}}\left(n\right)-u_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{bmi}}\left(n\right)=u_{\mathrm{bdmi}}\left(n\right)-u_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{cmi}}\left(n\right)=u_{\mathrm{cdmi}}\left(n\right)-u_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right)=i_{\mathrm{admi}}\left(n\right)-i_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{bmi}}\left(n\right)=i_{\mathrm{bdmi}}\left(n\right)-i_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{cmi}}\left(n\right)=i_{\mathrm{cdmi}}\left(n\right)-i_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(4\right)$

In formula, Δ u is disturbance voltage, and Δ i is current perturbation; N is the numbering of sampled point, is ordinal number, n=0,1, N is the sampling number of first-harmonic one-period; K gets a positive integer, K=1 or 2, or 3, the primitive period number of sampled point before the delayed disturbance of sampled point during being disturbance; Before subscript p represents that voltage dip occurs, when namely electrical network normally runs; During subscript d represents disturbance; Subscript m i is i-th monitoring point, and i is ordinal number, i=1,2, Subscript a, b, c represent a, b, c three-phase respectively; Subscript order: phase (p or period d-monitoring point mi before a, b or c)-disturbance;

Step b. asks the disturbance active power Δ P of mi point _mi, it equals the α β disturbance voltage vector Δ u of mi point _{α β mi}(n) and α β current perturbation vector Δ i _{α β mi}the inner product of (n), and get a primitive period move window integrated value, see formula (5)

$\left\{\begin{array}{c}\mathrm{\Δ}{p}_{\mathrm{mi}}\left(n\right)=\mathrm{\Δ}{i}_{\mathrm{\α\βmi}}{\left(n\right)}^T\·\mathrm{\Δ}{u}_{\mathrm{\α\βmi}}\left(n\right)\\ \mathrm{\Δ}{P}_{\mathrm{mi}}\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{j=n-N}^n\mathrm{\Δ}{p}_{\mathrm{mi}}\left(j\right)\end{array}\right.---\left(5\right)$

In formula (5), j is ordinal number; α β disturbance voltage vector and current perturbation vector are:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δu}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)\end{array}\right.---\left(6\right)$

Wherein: $C=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]$

Formula (7) is disturbance voltage vector and current perturbation vector:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{cmi}}\left(n\right)]}^T\\ {\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{cmi}}\left(n\right)]}^T\end{array}\right.---\left(7\right)$

Step c is according to the mean value Δ P of all wave disturbance active power of first-harmonic one _min () positioning voltage falls source temporarily; Can define arbitrarily a reference direction, this definition is what to be determined by the Same Name of Ends of potential and current transformers, and it is " just " that general definition load consumes active power; As power of disturbance Δ P _min () is timing, voltage sag source, and namely disturbing source is at the reverse direction of reference direction, also deserves to be called trip; As power of disturbance Δ P _min (), for time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream.

Beneficial effect, owing to have employed such scheme, the invention provides the new method of voltage Sag Disturbance source electricity in a kind of electrical network.Voltage dip source electricity, determines to cause the disturbing source of voltage dip to be positioned at which side of monitoring device exactly.Fault disturbance (other grid disturbances too), according to the superposition principle of linear circuit, is decomposed into 2 electrical networks that electrical network normally runs and only has disturbance source forcing by the present invention.In general, occur that the probability of plural short trouble is still very low in electric system, therefore, the same time only need consider to only have a disturbing source in electric system simultaneously.When only there being a disturbance voltage source excitation in electrical network, the distribution of disturbance active power stream in electrical network is deterministic, and therefore, its direction determines with regard to determinacy which side causing the disturbing source of voltage dip to be positioned at monitoring device.Proved by the l-G simulation test of same power network model, it can fall source, i.e. correct localization 100% by determinacy ground positioning voltage temporarily, and existing method correct localization generally only has about 80%, the judgment accuracy in right title voltage Sag Disturbance source is lower, maybe can not judge.Therefore, be a kind of voltage sag source localization method of great practical value.This voltage sag source localization method needs to carry out synchronized sampling to the voltage and current of monitoring point.

Advantage: the voltage dip caused by various electric network fault is located on this voltage sag source localization method energy determinacy ground, be applicable to radiant type, ring type, single loop, two-circuit, single supply and many power nets shelf structure electrical network, be also applicable to capacitor switching, transformer switching, heavy motor start the voltage dip source electricity that causes of disturbance.

Accompanying drawing explanation

Fig. 1 is synchronized sampling schematic diagram before and after fault of the present invention.

The f point short trouble figure that Fig. 2 (a) is power supply network equivalent circuit during f point failure of the present invention.

The f point short trouble equivalent circuit diagram that Fig. 2 (b) is power supply network equivalent circuit during f point failure of the present invention.

(namely electrical network normally runs) equivalent circuit diagram before the fault disturbance that Fig. 3 (a) is equivalent circuit during generation disturbance of the present invention.

The disturbing source equivalent circuit diagram of equivalent circuit during Fig. 3 (b) generation disturbance of the present invention.

Embodiment

Embodiment 1: the present invention, according to the superposition principle of linear circuit, obtains in electric network fault process under the effect of disturbance voltage, falls source temporarily with the accurate positioning voltage in direction of disturbance active power stream; Disturbance active power is timing, and disturbing source is in the upstream of monitoring point; Disturbance active power is for time negative, and disturbing source is in the downstream of monitoring point;

Concrete steps are as follows:

Step a. establishes phaselocked loop, when electrical network normally runs, before namely voltage dip occurs, in monitoring point to three-phase voltage and electric current respectively with the N number of point of per primitive period synchronized sampling: u _ami(n), u _bmi(n), u _cmi(n) and i _ami(n), i _bmi(n), i _cmi(n); Centering point useful earthing electric network, is calculated the root-mean-square value of each phase-to-ground voltage by formula (1); Centering point non-useful earthing electric network, is calculated the root-mean-square value of each relative neutral point of electric network voltage by formula (2); When the root-mean-square value of any phase voltage is less than the specified phase voltage of 90%, voltage Sag Disturbance occurs;

$\left\{\begin{array}{c}{U}_{\mathrm{ami}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{ami}}\left(n\right)\right]}^2}\\ U_{\mathrm{bmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{bmi}}\left(n\right)\right]}^2}\\ U_{\mathrm{cmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{cmi}}\left(n\right)\right]}^2}\end{array}\right.---\left(1\right)$

$\left\{\begin{array}{c}{U}_{\mathrm{ami}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{ami}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\\ U_{\mathrm{bmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{bmi}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\\ U_{\mathrm{cmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{cmi}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\end{array}\right.---\left(2\right)$

In formula, U _ami, U _bmi, U _cmithe three-phase voltage u that monitoring point mi records respectively _ami(n), u _bmi(n), u _cmithe root-mean-square value of (n), $u_{\mathrm{mi}}^0\left(n\right)=[u_{\mathrm{ami}}\left(n\right)+u_{\mathrm{bmi}}\left(n\right)+u_{\mathrm{cmi}}\left(n\right)]/3$ It is the residual voltage of electrical network;

Voltage dip pushes away forward KN sampled point, sees Fig. 1, get voltage Sag Disturbance three-phase electric current and voltage sampled value: u after occurring _apmi(n-KN), u _bpmi(n-KN), u _cpmiand i (n-KN) _apmi(n-KN), i _bpmi(n-KN), i _cpmi(n-KN) three-phase voltage, and continuation is sampled during disturbance, electric current obtain: u _admi(n), u _bdmi(n), u _cdmi(n) and i _admi(n), i _bdmi(n), i _cdmi(n), try to achieve disturbance voltage and current:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right)=u_{\mathrm{admi}}\left(n\right)-u_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{bmi}}\left(n\right)=u_{\mathrm{bdmi}}\left(n\right)-u_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{cmi}}\left(n\right)=u_{\mathrm{cdmi}}\left(n\right)-u_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right)=i_{\mathrm{admi}}\left(n\right)-i_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{bmi}}\left(n\right)=i_{\mathrm{bdmi}}\left(n\right)-i_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{cmi}}\left(n\right)=i_{\mathrm{cdmi}}\left(n\right)-i_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(4\right)$

In formula, Δ u is disturbance voltage, and Δ i is current perturbation; N is the numbering of sampled point, is ordinal number, n=0,1, N is the sampling number of first-harmonic one-period; K gets a positive integer, K=1 or 2, or 3, the primitive period number of sampled point before the delayed disturbance of sampled point during being disturbance; Before subscript p represents that voltage dip occurs, when namely electrical network normally runs; During subscript d represents disturbance; Subscript m i is i-th monitoring point, and i is ordinal number, i=1,2, Subscript a, b, c represent a, b, c three-phase respectively; Subscript order: phase (p or period d-monitoring point mi before a, b or c)-disturbance;

The disturbance voltage vector monitored at monitoring point mi and current phasor are:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{mi}}\left(t\right)={[{\mathrm{\Δu}}_{\mathrm{ami}}\left(t\right),{\mathrm{\Δu}}_{\mathrm{bmi}}\left(t\right),{\mathrm{\Δu}}_{\mathrm{cmi}}\left(t\right)]}^T\\ {\mathrm{\Δi}}_{\mathrm{mi}}\left(t\right)={[{\mathrm{\Δi}}_{\mathrm{ami}}\left(t\right),{\mathrm{\Δi}}_{\mathrm{bmi}}\left(t\right),{\mathrm{\Δi}}_{\mathrm{cmi}}\left(t\right)]}^T\end{array}\right.$

In formula: $\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{ami}}\left(t\right)=u_{\mathrm{admi}}\left(t\right)-u_{\mathrm{apmi}}\left(t\right)\\ {\mathrm{\Δu}}_{\mathrm{bmi}}\left(t\right)=u_{\mathrm{bdmi}}\left(t\right)-u_{\mathrm{bpmi}}\left(t\right)\\ {\mathrm{\Δu}}_{\mathrm{cmi}}\left(t\right)=u_{\mathrm{cdmi}}\left(t\right)-u_{\mathrm{cpmi}}\left(t\right)\end{array}\right.,\left\{\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{ami}}\left(t\right)=i_{\mathrm{admi}}\left(t\right)-i_{\mathrm{apmi}}\left(t\right)\\ \mathrm{\Δ}{i}_{\mathrm{bmi}}\left(t\right)=i_{\mathrm{bdmi}}\left(t\right)-i_{\mathrm{bpmi}}\left(t\right)\\ {\mathrm{\Δi}}_{\mathrm{cmi}}\left(t\right)=i_{\mathrm{cdmi}}\left(t\right)-i_{\mathrm{cpmi}}\left(t\right)\end{array}\right.$

Because front mi monitoring point voltage u occurs in disturbance _apmi(m), u _bpmi(m), u _cpmi(m), current i _apmi(m), i _bpmi(m), i _cpmi(m), m is also the numbering of sampled point, is ordinal number, m=0,1, With disturbance period mi monitoring point voltage u _{admi (}n), u _bdmi(n), u _cdmi(n), current i _admi(n), i _bdmi(n), i _cdmin () is 2 not values in the same time, for trying to achieve disturbance voltage and current amount, if phaselocked loop, to each cycle synchronisation sampling of voltage and current, as shown in Figure 1, try to achieve disturbance voltage and the current perturbation of monitoring point mi:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right)=u_{\mathrm{admi}}\left(n\right)-u_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{bmi}}\left(n\right)=u_{\mathrm{bdmi}}\left(n\right)-u_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{cmi}}\left(n\right)=u_{\mathrm{cdmi}}\left(n\right)-u_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right)=i_{\mathrm{admi}}\left(n\right)-i_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{bmi}}\left(n\right)=i_{\mathrm{bdmi}}\left(n\right)-i_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{cmi}}\left(n\right)=i_{\mathrm{cdmi}}\left(n\right)-i_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(4\right)$

In formula, Δ u is disturbance voltage, and Δ i is current perturbation; N is the numbering of sampled point, is ordinal number, n=0,1, N is the sampling number of first-harmonic one-period; M=n-KN; K gets a positive integer, K=1 or 2, or 3, the primitive period number of sampled point before the delayed disturbance of sampled point during being disturbance; Before subscript p represents that voltage dip occurs, when namely electrical network normally runs; During subscript d represents disturbance; Subscript m i is i-th monitoring point, and i is ordinal number, i=1,2, Subscript a, b, c represent a, b, c three-phase respectively; Subscript order: phase (p or period d-monitoring point mi before a, b or c)-disturbance;

Step b. asks the disturbance active power Δ P of mi point _mi, it equals the α β disturbance voltage vector Δ u of mi point _{α β mi}(n) and α β current perturbation vector Δ i _{α β mi}the inner product of (n), and get a primitive period move window integrated value, see formula (5)

$\left\{\begin{array}{c}\mathrm{\Δ}{p}_{\mathrm{mi}}\left(n\right)=\mathrm{\Δ}{i}_{\mathrm{\α\βmi}}{\left(n\right)}^T\·\mathrm{\Δ}{u}_{\mathrm{\α\βmi}}\left(n\right)\\ \mathrm{\Δ}{P}_{\mathrm{mi}}\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{j=n-N}^n\mathrm{\Δ}{p}_{\mathrm{mi}}\left(j\right)\end{array}\right.---\left(5\right)$

In formula (5), j is ordinal number; α β disturbance voltage vector and current perturbation vector are:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δu}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)\end{array}\right.---\left(6\right)$

Wherein: $C=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]$

Formula (7) is disturbance voltage vector and current perturbation vector:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{cmi}}\left(n\right)]}^T\\ {\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{cmi}}\left(n\right)]}^T\end{array}\right.---\left(7\right)$

After obtaining three-phase disturbance voltage (formula (3)) and current perturbation (formula (4)), disturbance voltage vector and current perturbation vector expression (7) can be obtained:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{cmi}}\left(n\right)]}^T\\ {\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{cmi}}\left(n\right)]}^T\end{array}\right.---\left(7\right)$

Clarke transform is carried out to formula (7) and obtains α β disturbance voltage vector and current perturbation vector expression (6):

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δu}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)\end{array}\right.---\left(6\right)$

α β disturbance voltage vector Δ u _{α β mi}(n) and α β current perturbation vector Δ i _{α β mi}n () asks inner product, and get a primitive period move window integrated value, obtain the disturbance active power Δ P of mi point _mi:

$\left\{\begin{array}{c}\mathrm{\Δ}{p}_{\mathrm{mi}}\left(n\right)=\mathrm{\Δ}{i}_{\mathrm{\α\βmi}}{\left(n\right)}^T\·\mathrm{\Δ}{u}_{\mathrm{\α\βmi}}\left(n\right)\\ \mathrm{\Δ}{P}_{\mathrm{mi}}\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{j=n-N+1}^n\mathrm{\Δ}{p}_{\mathrm{mi}}\left(j\right)\end{array}\right.---\left(5\right)$

Step c is according to the mean value Δ P of all wave disturbance active power of first-harmonic one _min () positioning voltage falls source temporarily; Can define arbitrarily a reference direction, this definition is what to be determined by the Same Name of Ends of potential and current transformers, and it is " just " that general definition load consumes active power; As power of disturbance Δ P _min () is timing, voltage sag source (i.e. disturbing source), at the reverse direction of reference direction, also deserves to be called trip; As power of disturbance Δ P _min (), for time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream.

In electric system, voltage dip is because disturbance in electrical network (as: switching etc. of the startup of short trouble, heavy motor, electric capacity) causes.For most typical short-circuit fault of power system disturbance, in general, in electric system, occur that the probability of plural short trouble is still very low simultaneously, therefore, here only consider to only have a short trouble in electric system, and think that the element in electric system is linear, simplify equivalent circuit as shown in Fig. 2 (a), can be equivalent to as Fig. 2 (b) circuit.In figure: u _s1(t)=[u _aS1(t), u _bS1(t), u _cS1(t)] ^t, Z _s1for supply side equivalent source and internal impedance, u _s2(t)=[u _aS2(t), u _bS2(t), u _bdmi(t), u _cdmi(t)] ^t, Z _s2for electricity consumption side equivalent source and internal impedance, below " → " represents the reference direction of this monitoring point mi.During subscript d represents disturbance; Mi is i-th monitoring point, and Li represents i-th circuit, and Si represents power supply, and i is ordinal number, i=1,2, A, b, c represent a, b, c three-phase respectively.Subscript order: phase (p or period d-monitoring point mi before a, b or c)-disturbance.

In Fig. 2 (b), u _df(t)=[u _adf(t), u _bdf(t), u _cdf(t)] ^tthe voltage of trouble spot between age at failure.Can be analyzed to u _pf(t)=[u _apf(t), u _bpf(t), u _cpf(t)] ^tf point voltage and fault disturbance voltage Δ u before disturbance _f(t)=u _df(t)-u _pf(t)=[Δ u _af(t), Δ u _bf(t), Δ u _cf(t)] ^ttwo parts, therefore, according to the superposition principle of linear circuit, with Fig. 3 (a) with (b) and next equivalent.Fig. 3 (a) is the equivalent electrical circuit of (namely electrical network normally runs) before fault disturbance, and Fig. 3 (b) is then the equivalent circuit only had under disturbance voltage source excitation.

Fig. 3 illustrates, when electrical network generation disturbance, can be substituted by the superposition of the equivalent circuit before a disturbance and an equivalent circuit only under disturbance voltage source excitation.Only under the excitation of disturbance voltage source, can intuitively be found out by Fig. 3 (b), if with from left to right, namely below mi, " → " is positive flow path direction, then when power of disturbance stream is timing, voltage sag source (i.e. disturbing source) is in upstream, and when power of disturbance stream is for time negative, voltage sag source is in downstream.Here it is herein to the theoretical foundation of voltage dip source electricity.

Because the direction of the poower flow of monitoring point in Fig. 3 (b) is only relevant with the impedance of disturbing source each branch road in the position of grid structure and grid structure and rack with size, irrelevant with power supply, actual direction of tide and power load, therefore, this basis for estimation is applicable to any grid structure (single supply radiant type, dual power supply radiant type, annular electrical network etc.).Here " poower flow is just reference from left to right " is also no longer " actual trend " direction before disturbance, but the reference direction that can define arbitrarily, be actually and determined by the Same Name of Ends of potential and current transformers, it is " just " that general definition load consumes active power stream.

Claims (1)

1. based on the voltage sag source localization method in power of disturbance direction, it is characterized in that: according to the superposition principle of linear circuit, obtain in electric network fault process under the effect of disturbance voltage, fall source temporarily with the accurate positioning voltage in direction of disturbance active power stream; Disturbance active power is timing, and disturbing source is in the upstream of monitoring point; Disturbance active power is for time negative, and disturbing source is in the downstream of monitoring point;

Concrete steps are as follows:

Step a. establishes phaselocked loop, when electrical network normally runs, before namely voltage dip occurs, in monitoring point to three-phase voltage and electric current respectively with the N number of point of per primitive period synchronized sampling: u _ami(n), u _bmi(n), u _cmi(n) and i _ami(n), i _bmi(n), i _cmi(n); Centering point useful earthing electric network, is calculated the root-mean-square value of each phase-to-ground voltage by formula (1); Centering point non-useful earthing electric network, is calculated the root-mean-square value of each relative neutral point of electric network voltage by formula (2); When the root-mean-square value of any phase voltage is less than the specified phase voltage of 90%, voltage Sag Disturbance occurs;

$\left\{\begin{array}{c}{U}_{\mathrm{ami}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{ami}}\left(n\right)\right]}^2}\\ U_{\mathrm{bmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{bmi}}\left(n\right)\right]}^2}\\ U_{\mathrm{cmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{\left[u_{\mathrm{cmi}}\left(n\right)\right]}^2}\end{array}\right.---\left(1\right)$

$\left\{\begin{array}{c}{U}_{\mathrm{ami}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{ami}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\\ U_{\mathrm{bmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{bmi}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\\ U_{\mathrm{cmi}}=\sqrt{\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}{[u_{\mathrm{cmi}}\left(n\right)-u_{\mathrm{mi}}^0\left(n\right)]}^2}\end{array}\right.---\left(2\right)$

In formula, U _ami, U _bmi, U _cmithe three-phase voltage u that monitoring point mi records respectively _ami(n), u _bmi(n), u _cmithe root-mean-square value of (n), $u_{\mathrm{mi}}^0\left(n\right)=[u_{\mathrm{ami}}\left(n\right)+u_{\mathrm{bmi}}\left(n\right)+u_{\mathrm{cmi}}\left(n\right)]/3$ It is the residual voltage of electrical network;

Voltage dip pushes away forward KN sampled point, gets voltage Sag Disturbance three-phase electric current and voltage sampled value: u after occurring _apmi(n-KN), u _bpmi(n-KN), u _cpmiand i (n-KN) _apmi(n-KN), i _bpmi(n-KN), i _cpmi(n-KN) three-phase voltage, and continuation is sampled during disturbance, electric current obtain: u _admi(n), u _bdmi(n), u _cdmi(n) and i _admi(n), i _bdmi(n), i _cdmi(n), try to achieve disturbance voltage and current:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right)=u_{\mathrm{admi}}\left(n\right)-u_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{bmi}}\left(n\right)=u_{\mathrm{bdmi}}\left(n\right)-u_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{u}_{\mathrm{cmi}}\left(n\right)=u_{\mathrm{cdmi}}\left(n\right)-u_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right)=i_{\mathrm{admi}}\left(n\right)-i_{\mathrm{apmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{bmi}}\left(n\right)=i_{\mathrm{bdmi}}\left(n\right)-i_{\mathrm{bpmi}}(n-\mathrm{KN})\\ \mathrm{\Δ}{i}_{\mathrm{cmi}}\left(n\right)=i_{\mathrm{cdmi}}\left(n\right)-i_{\mathrm{cpmi}}(n-\mathrm{KN})\end{array}\right.---\left(4\right)$

In formula, Δ u is disturbance voltage, and Δ i is current perturbation; N is the sequence number of sampled point, is ordinal number, n=0,1, N is the sampling number of first-harmonic one-period; K gets a positive integer, K=1 or 2, or 3, the primitive period number of sampled point before the delayed disturbance of sampled point during being disturbance; Before subscript p represents that voltage dip occurs, when namely electrical network normally runs; During subscript d represents disturbance; Subscript m i is i-th monitoring point, and i is ordinal number, i=1,2, Subscript a, b, c represent a, b, c three-phase respectively; Subscript order: phase (p or period d-monitoring point mi before a, b or c)-disturbance;

Step b. asks the disturbance active power Δ P of mi point _mi, it equals the α β disturbance voltage vector Δ u of mi point _{α β mi}(n) and α β current perturbation vector Δ i _{α β mi}n the inner product of (), and the integrated value of getting a primitive period, be shown in formula (5)

$\left\{\begin{array}{c}\mathrm{\Δ}{p}_{\mathrm{mi}}\left(n\right)=\mathrm{\Δ}{i}_{\mathrm{\α\βmi}}{\left(n\right)}^T\·\mathrm{\Δ}{u}_{\mathrm{\α\βmi}}\left(n\right)\\ \mathrm{\Δ}{P}_{\mathrm{mi}}\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{j=n-N}^n\mathrm{\Δ}{p}_{\mathrm{mi}}\left(j\right)\end{array}\right.---\left(5\right)$

In formula (5), j is ordinal number; α β disturbance voltage vector and current perturbation vector are:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δu}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\α\βmi}}\left(n\right)=\left[\begin{array}{c}{\mathrm{\Δi}}_{\mathrm{\αmi}}\left(n\right)\\ {\mathrm{\Δi}}_{\mathrm{\βmi}}\left(n\right)\end{array}\right]=C\·{\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)\end{array}\right.---\left(6\right)$

Wherein: $C=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]$

Formula (7) is disturbance voltage vector and current perturbation vector:

$\left\{\begin{array}{c}{\mathrm{\Δu}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δu}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δu}}_{\mathrm{cmi}}\left(n\right)]}^T\\ {\mathrm{\Δi}}_{\mathrm{mi}}\left(n\right)={[{\mathrm{\Δi}}_{\mathrm{ami}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{bmi}}\left(n\right),{\mathrm{\Δi}}_{\mathrm{cmi}}\left(n\right)]}^T\end{array}\right.---\left(7\right)$

Step c is according to the mean value Δ P of all wave disturbance active power of first-harmonic one _min () positioning voltage falls source temporarily.Can define arbitrarily a reference direction, this definition is what to be determined by the Same Name of Ends of potential and current transformers, and it is " just " that general definition load consumes active power; As power of disturbance Δ P _min () is timing, voltage sag source, and namely disturbing source is at the reverse direction of reference direction, also deserves to be called trip; As power of disturbance Δ P _min (), for time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream.