CN104215882A - Voltage sag source locating method based on active single-port network resistor polarity - Google Patents

Abstract

The invention discloses a voltage sag source locating method based on an active single-port network resistor polarity and belongs to automatic monitoring and locating methods for power grid voltage sag source locating. The voltage sag source locating method includes that a voltage sag source direction is judged accurately by measuring a real component polarity of external characteristic impedance of an active single-port network according to a linear active single-port network theory; when the real component polarity of the external characteristic impedance is positive, a disturbing source is at the upstream position of a monitoring point; when the real component polarity of the external characteristic impedance is negative, the disturbing source is at the downstream position of the monitoring point; a corresponding algorithm for the real component polarity of the external characteristic impedance is defined and provided. The voltage sag source locating method based on the active single-port network resistor polarity has the advantages that the method is capable of locating voltage sag caused by various power grid faults determinately and applicable to power grids of radiation-type, ring-type, single-loop, double-loop, single-power-source and multi-power-source grid structures as well as voltage sag source locating caused by disturbance resulting from capacitor switching, transformer switching, large motor starting; voltage and current of the monitoring point need to be sampled synchronously according to the voltage sag source locating method.

Description

A kind of voltage sag source localization method based on active one port network resistor polarity

Technical field

The present invention relates to the automatic monitoring and positioning method that source electricity falls in a kind of line voltage temporarily, particularly a kind of voltage sag source localization method based on active one port network resistor polarity.

Background technology

Voltage dip, refers to that supply voltage root-mean-square value drops to suddenly 90% ~ 10% of rated voltage amplitude at short notice, 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, voltage dip source electricity causes the concern of domestic and international researcher in recent years.

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 prior art Problems existing, a kind of voltage sag source localization method based on active one port network resistor polarity is provided, realize the automatic Monitoring and Positioning 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: theoretical according to linear active one port network, accurately judged the direction of voltage sag source by the real part polarity of the external characteristic impedance of measuring active one port network; The real part polarity of external characteristic impedance is timing, and disturbing source is in the upstream of monitoring point; The real part polarity of external characteristic impedance 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:

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

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

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. is asked real part and the imaginary part of each phase disturbance voltage of mi point by formula (5) and (6):

$\left\{\begin{array}{c}\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{u}_{\mathrm{xmi}}\left(n\right)\·\cos (2\mathrm{\πn}/N)\\ \mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{u}_{\mathrm{xmi}}\left(n\right)\·\sin (2\mathrm{\πn}/N)\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{i}_{\mathrm{xmi}}\left(n\right)\·\cos (2\mathrm{\πn}/N)\\ \mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{i}_{\mathrm{xmi}}\left(n\right)\·\sin (2\mathrm{\πn}/N)\end{array}\right.---\left(6\right)$

In formula, with be respectively x phase voltage and current disturbing phasor with real part, with be respectively phase voltage and current disturbing phasor with imaginary part, x ∈ [a, b, c]; The real part R of the active one port network external characteristic impedance of mi monitoring point x ∈ [a, b, c] phase is calculated again by formula (7) _exmi;

$R_{\mathrm{exmi}}=\frac{{\left(\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\right)}^2+{\left(\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{im}}\right)}^2}{\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\·\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{rs}}+{\mathrm{\ΔU}}_{\mathrm{xmi}}^{\mathrm{im}}\·\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{im}}}---\left(7\right)$

Step c is according to the real part R of the active one port network external characteristic impedance of monitoring point mi _exmipolarity orientation voltage sag source.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 one definition load consumes active power; Only to voltage dip phase, namely phase voltage is less than the phase of 90% specified phase voltage, judges, as the real part R of the active one port network external characteristic impedance of monitoring point mi _exmifor timing, voltage sag source, namely disturbing source is at the reverse direction of reference direction, also deserves to be called trip; As the real part R of the active one port network external characteristic impedance of monitoring point mi _exmifor time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream.

Beneficial effect, owing to have employed such scheme, voltage dip source electricity, determines to cause the disturbing source of voltage dip to be positioned at which side of monitoring device exactly.The present invention is theoretical according to active one port network, and any electrical network is observed from monitoring point to non-disturbance side, can be equivalent to 1 active linear one port network; For power distribution network, capacity of short circuit is not very large, can be similar to and think that the power supply in this port network is infinitely great power supply, therefore, this 1 active one port network can be equivalent with " Dai Weinan circuit ", namely for external circuit, always can replace with the active leg that an ideal voltage source and linear impedance are in series; An active current reference direction " is determined " in any mi monitoring point, the active current reference direction of this " determination " " is determined " by the electric current of mi monitoring point monitoring device and the polarity of voltage transformer (VT) and Same Name of Ends, and it is positive reference direction that one given load consumes active power.So, under the positive reference direction condition of this regulation, the real part recording the impedance of active one port network external characteristic as monitoring point mi is timing, voltage sag source, and namely disturbing source is at the reverse direction of reference direction, also deserves to be called trip; When monitoring point mi records the real part of active one port network external characteristic impedance for time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream.Proved by the l-G simulation test of same power network model, its can determinacy ground positioning voltage temporarily source fall, i.e. correct localization 100%, and existing method correct localization one only have 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.

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.

Fig. 2 is equivalent circuit of electric power network figure of the present invention.

Fig. 3 is the present invention's " Dai Weinan circuit " external characteristic figure; In figure: I _smifor the short-circuit current effective value of monitoring point mi, A.

Embodiment

Embodiment 1: the present invention is theoretical according to linear active one port network, is accurately judged the direction of voltage sag source by the real part polarity of the external characteristic impedance of measuring active one port network; The real part polarity of external characteristic impedance is timing, and disturbing source is in the upstream of monitoring point; The real part polarity of external characteristic impedance 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 _cmimonitoring point respectively _mithe three-phase voltage u recorded _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:

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

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

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 and current monitored at monitoring point mi is respectively:

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

Because front mi monitoring point voltage u occurs in disturbance _apmi(n), u _{bpmi (m}), u _cpmi(m), current i _apmi(m) i _bpmi(n), 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 _admin () is 2 not sampled 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, try to achieve disturbance voltage and the current perturbation of monitoring point mi:

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

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

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; When subscript p represents that before voltage dip occurs, 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. is asked real part and the imaginary part of each phase disturbance voltage of mi point by formula (5) and (6):

$\left\{\begin{array}{c}\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{u}_{\mathrm{xmi}}\left(n\right)\·\cos (2\mathrm{\πn}/N)\\ \mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{u}_{\mathrm{xmi}}\left(n\right)\·\sin (2\mathrm{\πn}/N)\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{i}_{\mathrm{xmi}}\left(n\right)\·\cos (2\mathrm{\πn}/N)\\ \mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{i}_{\mathrm{xmi}}\left(n\right)\·\sin (2\mathrm{\πn}/N)\end{array}\right.---\left(6\right)$

In formula, with be respectively x phase voltage and current disturbing phasor with real part, with be respectively x phase voltage and current disturbing phasor with imaginary part, x ∈ [a, b, c]; The real part R of the active one port network external characteristic impedance of mi monitoring point x ∈ [a, b, c] phase is calculated again by formula (7) _exmi;

$R_{\mathrm{exmi}}=\frac{{\left(\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\right)}^2+{\left(\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{im}}\right)}^2}{\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\·\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{rs}}+{\mathrm{\ΔU}}_{\mathrm{xmi}}^{\mathrm{im}}\·\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{im}}}---\left(7\right)$

The real part of formula (3) and (4) and imaginary part can be tried to achieve by formula (5) and (6):

$\left\{\begin{array}{c}\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{u}_{\mathrm{xmi}}\left(n\right)\·\cos (2\mathrm{\πn}/N)\\ \mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{u}_{\mathrm{xmi}}\left(n\right)\·\sin (2\mathrm{\πn}/N)\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{i}_{\mathrm{xmi}}\left(n\right)\·\cos (2\mathrm{\πn}/N)\\ \mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{i}_{\mathrm{xmi}}\left(n\right)\·\sin (2\mathrm{\πn}/N)\end{array}\right.---\left(6\right)$

In formula, with be respectively x phase voltage and current disturbing phasor with real part, with be respectively phase voltage and current disturbing phasor with imaginary part, x ∈ [a, b, c];

The real part of the characteristic impedance of active two-port network is:

Wherein: Δ U _xmiwith Δ I _xmibe respectively the effective value of x phase disturbance voltage and current perturbation; for the disturbance voltage that x phase records in mi monitoring point with current perturbation phase differential between phasor.By formula (5) and (6) for people's above formula, obtain formula (7):

$R_{\mathrm{exmi}}=\frac{{\left(\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\right)}^2+{\left(\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{im}}\right)}^2}{\mathrm{\Δ}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\·\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{rs}}+{\mathrm{\ΔU}}_{\mathrm{xmi}}^{\mathrm{im}}\·\mathrm{\Δ}{I}_{\mathrm{xmi}}^{\mathrm{im}}}---\left(7\right)$

Step c is according to the real part R of the active one port network external characteristic impedance of monitoring point mi _exmipolarity orientation voltage sag source; 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 one definition load consumes active power; Only to voltage dip phase, namely phase voltage is less than the phase of 90% specified phase voltage, judges, as the real part R of the active one port network external characteristic impedance of monitoring point mi _exmifor timing, voltage sag source and disturbing source, at the reverse direction of reference direction, also deserve to be called trip; As the real part R of the active one port network external characteristic impedance of monitoring point mi _exmifor time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream;

Voltage dip source electricity is exactly determine voltage sag source that side at monitoring device; In electric system, voltage dip is because the switching disturbance of short trouble, heavy motor startup, electric capacity causes in electrical network; For most typical short-circuit fault of power system disturbance, one in fact, occurs that in electric system the probability of plural short trouble is still very low, therefore simultaneously, here only consider to only have a short trouble in electric system, and think that the element in electric system is linear; Any electrical network is observed to both sides from monitoring point, 2 active linear one port networks in monitoring point cascade can be equivalent to respectively; For power distribution network, capacity of short circuit is not very large, can be similar to and think that the power supply in 2 port networks is infinitely great power supply, therefore, these 2 active one port networks can be equivalent with " Dai Weinan circuit ", namely for external circuit, always can replace, as Fig. 2 with the active leg that an ideal voltage source and linear impedance are in series; An active current reference direction " is determined " in any mi monitoring point, the active current reference direction of this " determination " " is determined " by the electric current of mi monitoring point monitoring device and the polarity of voltage transformer (VT) and Same Name of Ends, and it is positive reference direction that one given load consumes active power; When left side circuit is supply side, right side circuit is electricity consumer side, and regulation is just be from left to right to the reference direction of mi monitoring point, as " → " below mi in Fig. 1; For a mounted voltage sag source Position monitoring devices, the active current positive dirction of monitoring point is determined; So, under the positive reference direction condition of this regulation, the external characteristic impedance from any one port network 2 active one port networks records:

$Z_{\mathrm{emi}}=\frac{\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{mi}}}{\mathrm{\Δ}{\stackrel{\·}{I}}_{\mathrm{mi}}}{R}_{\mathrm{emi}}+j{X}_{\mathrm{emi}}$

In formula, $\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{mi}}={\stackrel{\·}{U}}_{\mathrm{dmi}}-{\stackrel{\·}{U}}_{\mathrm{pmi}},{\mathrm{\Δ}\stackrel{\·}{I}}_{\mathrm{mi}}={\stackrel{\·}{I}}_{\mathrm{dmi}}-{\stackrel{\·}{I}}_{\mathrm{pmi}},{\stackrel{\·}{U}}_{\mathrm{dmi}},{\stackrel{\·}{I}}_{\mathrm{dmi}}$ For during fault disturbance in the voltage and current phasor that mi point records, for before fault disturbance in the voltage and current phasor that mi point records.If the real part R of characteristic impedance _emibe less than zero, then fault disturbance source is in the equidirectional with monitoring point active current reference direction, i.e. downstream; On the contrary, if the real part R of characteristic impedance _emibe greater than zero, then fault disturbance source is in the reverse direction with monitoring point active current reference direction, i.e. upstream; In formula, Z _emithere is clear and definite physical significance, the external characteristic impedance of 2 active one port networks and Dai Weinan circuit; Because these 2 port networks are in the cascade of mi point, therefore, these 2 port networks have same external characteristic impedance at mi point; Just owing to determining in the current reference direction of mi point, one is that electric current flows out (on the left of Fig. 2) from port network, another is then that electric current flows into port network (on the right side of Fig. 2) from outside, and the direction in current reference direction makes the polarity of the external characteristic impedance recorded from these 2 port networks be contrary; Be and judge that voltage Sag Disturbance occurs in the foundation of that side of mi (namely in that port network); This theoretical foundation based on port network external characteristic impedance real part polarity orientation voltage sag source also can be proven from below;

In fig. 2, if fault is in electricity consumer side, then by non-faulting disturbance side, before namely obtaining fault disturbance from supply side " Dai Weinan circuit ":

${\stackrel{\·}{U}}_{\mathrm{pmi}}={\stackrel{\·}{E}}_1-{\stackrel{\·}{I}}_{\mathrm{pmi}}{Z}_1$

If during fault disturbance, the voltage increment of mi monitoring point is current increment is $\mathrm{\Δ}{\stackrel{\·}{I}}_{\mathrm{mi}}={\stackrel{\·}{I}}_{\mathrm{pmi}}-{\stackrel{\·}{I}}_{\mathrm{dmi}},$ Then:

${\stackrel{\·}{U}}_{\mathrm{pmi}}+\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{mi}}={\stackrel{\·}{E}}_1-({\stackrel{\·}{I}}_{\mathrm{pmi}}+\mathrm{\Δ}{\stackrel{\·}{I}}_{\mathrm{mi}})Z_1$

Subtract each other and arrange:

$Z_1=R_1+{\mathrm{jX}}_1=-\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{mi}}/\mathrm{\Δ}{\stackrel{\·}{I}}_{\mathrm{mi}}=-Z_{\mathrm{emi}}=-(R_{\mathrm{emi}}+{\mathrm{jX}}_{\mathrm{emi}})$

According to the direction of current reference shown in Fig. 2, supply side power supply power supply, Z ₁dissipative cell, therefore, Z ₁real part R ₁> 0, must have R _emi< 0, fault disturbance source is in the equidirectional with monitoring point active current reference direction, i.e. downstream.In fact, according to the current reference direction of Fig. 2, namely current reference direction is flowed out from port network, and the slope of the external characteristic of supply side " Dai Weinan circuit " is negative value, as Fig. 3 first quartile straight line, therefore, and R _emi< 0;

If fault is at supply side, then same by non-faulting disturbance side, before namely obtaining fault disturbance from electricity consumer side " Dai Weinan circuit ":

${\stackrel{\&CenterDot;}{U}}_{\mathrm{pmi}}={\stackrel{\&CenterDot;}{E}}_2+{\stackrel{\&CenterDot;}{I}}_{\mathrm{pmi}}{Z}_2$

During fault disturbance: ${\stackrel{\&CenterDot;}{U}}_{\mathrm{pmi}}+\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{U}}_{\mathrm{mi}}={\stackrel{\&CenterDot;}{E}}_2+({\stackrel{\&CenterDot;}{I}}_{\mathrm{pmi}}+\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{\mathrm{mi}})Z_2$

Subtract each other and arrange:

$Z_2=R_2+{\mathrm{jX}}_2=\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{U}}_{\mathrm{mi}}/\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{\mathrm{mi}}=Z_{\mathrm{emi}}=R_{\mathrm{emi}}+{\mathrm{jX}}_{\mathrm{emi}}$

According to the reference direction of active current shown in Fig. 2, electricity consumption side power supply send negative power, Z ₂dissipative cell, therefore, Z ₂real part R ₂> 0, must have Remi > 0, and fault disturbance source is in the reverse direction with monitoring point active current reference direction, i.e. upstream; In fact, according to the current reference direction of Fig. 2, namely current reference direction flows into port network from outside, the slope of the external characteristic of electricity consumption side " Dai Weinan circuit " be on the occasion of, as Fig. 3 second quadrant straight line, therefore, Remi > 0.

Claims (1)

1. the voltage sag source localization method based on active one port network resistor polarity, it is characterized in that: theoretical according to linear active one port network, accurately judged the direction of voltage sag source by the real part polarity of the external characteristic impedance of measuring active one port network; The real part polarity of external characteristic impedance is timing, and disturbing source is in the upstream of monitoring point; The real part polarity of external characteristic impedance 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;

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

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

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:

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

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

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. is asked real part and the imaginary part of each phase disturbance voltage of mi point by formula (5) and (6):

$\left\{\begin{array}{c}\mathrm{\&Delta;}{U}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\&Sigma;}}_{n=0}^{N-1}\mathrm{\&Delta;}{u}_{\mathrm{xmi}}\left(n\right)\&CenterDot;\cos (2\mathrm{\&pi;n}/N)\\ \mathrm{\&Delta;}{U}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\&Sigma;}}_{n=0}^{N-1}\mathrm{\&Delta;}{u}_{\mathrm{xmi}}\left(n\right)\&CenterDot;\sin (2\mathrm{\&pi;n}/N)\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}\mathrm{\&Delta;}{I}_{\mathrm{xmi}}^{\mathrm{rs}}=\frac{1}{N}{\mathrm{\&Sigma;}}_{n=0}^{N-1}\mathrm{\&Delta;}{i}_{\mathrm{xmi}}\left(n\right)\&CenterDot;\cos (2\mathrm{\&pi;n}/N)\\ \mathrm{\&Delta;}{I}_{\mathrm{xmi}}^{\mathrm{im}}=\frac{1}{N}{\mathrm{\&Sigma;}}_{n=0}^{N-1}\mathrm{\&Delta;}{i}_{\mathrm{xmi}}\left(n\right)\&CenterDot;\sin (2\mathrm{\&pi;n}/N)\end{array}\right.---\left(6\right)$

In formula, with be respectively x phase voltage and current disturbing phasor with real part, with be respectively phase voltage and current disturbing phasor with imaginary part, x ∈ [a, b, c]; The real part R of the active one port network external characteristic impedance of mi monitoring point x ∈ [a, b, c] phase is calculated again by formula (7) _exmi;

$R_{\mathrm{exmi}}=\frac{{\left(\mathrm{\&Delta;}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\right)}^2+{\left(\mathrm{\&Delta;}{U}_{\mathrm{xmi}}^{\mathrm{im}}\right)}^2}{\mathrm{\&Delta;}{U}_{\mathrm{xmi}}^{\mathrm{rs}}\&CenterDot;\mathrm{\&Delta;}{I}_{\mathrm{xmi}}^{\mathrm{rs}}+{\mathrm{\&Delta;U}}_{\mathrm{xmi}}^{\mathrm{im}}\&CenterDot;\mathrm{\&Delta;}{I}_{\mathrm{xmi}}^{\mathrm{im}}}---\left(7\right)$

Step c is according to the real part R of the active one port network external characteristic impedance of monitoring point mi _exmipolarity orientation voltage sag source; 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 one definition load consumes active power; Only to voltage dip phase, namely phase voltage is less than the phase of 90% specified phase voltage, judges, as the real part R of the active one port network external characteristic impedance of monitoring point mi _exmifor timing, voltage sag source, namely disturbing source is at the reverse direction of reference direction, also deserves to be called trip; As the real part R of the active one port network external characteristic impedance of monitoring point mi _exmifor time negative, voltage sag source, at the equidirectional of reference direction, also claims downstream.