CN104538938A - Recording-data-based protection safety margin assessment method - Google Patents

Abstract

The invention relates to a recording-data-based protection safety margin assessment method. A fault occurs at a power grid, wave recording is started and recording data are recorded, an electrical quantity value is calculated in a faulty mode by using the recording data based on a protection principle, and substitution of a protection operation criterion is carried out to calculate a protection setting value; a safety margin of current protection, a safety margin of low-voltage protection, and a safety margin of distance protection are respectively calculated; and a fault type is determined based on recording data at the two sides of the faulty line and a fault point position and a transition resistance are calculated, system equivalent impedances and equivalent potentials of the two sides of the faulty line are calculated, correlation branch coefficients of the electrical quantities of the two sides of the faulty line are calculated, and a fault with the same features is simulated. With the method, wave recording can be started automatically when the fault occurs at the power grid; the electrical quantity value can be calculated in a faulty mode by using the recording data based on the protection principle; and the protection operation criterion is substituted, thereby verifying the adaptability of the protection setting value.

Description

Based on the protection Safety Margin method of recorder data

Technical field

What the present invention relates to is a kind of technology of protecting electrical power system field, a kind of specifically protection Safety Margin method based on recorder data.

Background technology

Protective relaying device is the guarantee of safe operation of power system.The power outage on a large scale occurred both at home and abroad, incorrect operation that is most and protective relaying device has direct or indirect relation.Therefore, reasonable arrangement relay protection constant value is the essential condition ensureing electric power netting safe running.At present, the definite value of protective relaying device is that the minimum and maximum operational mode according to system under off-line state is adjusted, and remains unchanged or only switch between indivedual typical way in system cloud gray model.Along with the expansion of electrical network scale, run mode automatic identification gets more and more, and the mode after electric network fault is changeable especially.When system is in some special operational mode, in system, the definite value of part protection may not meet sensitivity and optionally requirement, there is the accident potential of relay fail or malfunction.If can not to go forward side by side Row sum-equal matrix by Timeliness coverage, power outage on a large scale may be caused.Compared with the off-line setting calculation of definite value, online relay setting check method owing to considering the physical cabling of current electric grid, trend, generating and load water in calculation of short-circuit current

Nowadays, electrical network scale constantly expands, and run mode automatic identification gets more and more, and the mode after electric network fault is changeable especially.When system is in some special operational mode, in system, the definite value of part protection may not meet sensitivity and optionally requirement, there is the accident potential of relay fail or malfunction.Definite value due to current protective relaying device is that the minimum and maximum operational mode according to system under off-line state is adjusted, and remains unchanged or only switch between indivedual typical way in system cloud gray model.Along with the expansion of electrical network scale, run mode automatic identification gets more and more, and the mode after electric network fault is changeable especially.When system is in some special operational mode, in system, the definite value of part protection may not meet sensitivity and optionally requirement, there is the accident potential of relay fail or malfunction.If can not to go forward side by side Row sum-equal matrix by Timeliness coverage, power outage on a large scale may be caused.

Through finding the retrieval of prior art, open (bulletin) the day 2014.04.30 of Chinese patent literature CN103762561A, discloses a kind of HVDC (High Voltage Direct Current) transmission system DC differential protection setting method.DC differential protection adopts three-stage protection mode, comprise protection I section, II section, III section, its setting method includes following process: 1) protection input variable is again through subtracter (2) after low pass filter (1) filtering, finally takes absolute value and obtains protecting input variable; 2) above-mentioned protection input variable compares with the definite value of I section comparator (3), if be greater than definite value, trigger TFR record ripple through delay time T1; 3) above-mentioned protection input variable compares with the definite value of II section comparator (4), if be greater than definite value, through delay time T2, starts emergency shutdown order; 4) above-mentioned protection input variable compares with the definite value of III section comparator (5), if be greater than definite value, through delay time T3, starts emergency shutdown order.This technology not only realizes the main protection of converter earth fault, and when avoiding system disturbance, measuring component transient characterisitics are inconsistent causes false protection, improves reliability.But the defect of this technology and deficiency are: what its protection seting value adopted is off-line setting calculation mode and adopts off-line protection fixed value adjusting; its validity is larger by the impact of each component models in electrical network and parameter accuracy; in addition, when the core concept of this technology is that protection input variable is greater than protection seting value, corresponding action is just produced through certain time-delay.

Summary of the invention

The present invention is directed to prior art above shortcomings, propose a kind of protection Safety Margin method based on recorder data, can automatically start record ripple when grid collapses.The Wave data of installation place electric parameters is protected when recorder data have recorded fault.Electric parameters when recorder data can be utilized to calculate fault according to protection philosophy, and substitute into protection act criterion, the adaptability of verification protection definite value.

The present invention is achieved by the following technical solutions, the present invention includes:

1) start record ripple record recorder data when the grid collapses, electric parameters when utilizing recorder data to calculate fault according to protection philosophy, substitutes into protection act criterion and calculates protection seting value;

Described recorder data comprises: the Wave data protecting installation place electric parameters during fault.

2) calculate protection margin of safety, specifically comprise: the margin of safety of the margin of safety of current protection, the margin of safety of under-voltage protection, distance protection;

3) whether failure judgement occurs in protection range at end, and concrete steps comprise:

3.1) utilize faulty line both sides recorder data failure judgement type, calculate position and the transition resistance of fault point;

3.2) calculate the system equivalent impedance of faulty line both sides and equivalent electromotive force, and calculate faulty line both sides electric parameters correlated branch coefficient;

3.3) fault mode (fault type, transition resistance) of simulating same feature moves on to faulty line end, recalculates the fault amount of protection installation place and upper level route protection installation place.

Technique effect

Because the operating characteristics of distance protection generally can be expressed as an operating space on impedance plane; only use sensitivity concept can not complete evaluation measurement impedance from the distance on each border of operating space; therefore the present invention carries out determining with the distance of quota portray fault amount from trip boundary with regard to protection margin of safety; thus can the margin of safety of qualitative assessment relay fail in order to verify end fault time protection definite value validity, and by simulating, verifying the validity of the method.Owing to utilizing fault recorder data to calculate, so computed information can real-time check, accurately reflect electrical network feature.

Compared with prior art; advantage of the present invention is mainly reflected in: the present invention proposes the definition of the tripping of protection seting value or malfunction margin of safety; the validity of protection seting value is judged by margin of safety; problem existing for Timeliness coverage electric power system also adjusts; maximum possible reduces the generation of power outage on a large scale; decrease man power and material's cost, reduce the loss brought because of electric power system fault.

Concerning power system transmission line, the size of transition resistance and the environmental condition of fault point closely related.When after circuit generation primary fault; if the margin of safety utilizing this method to calculate is lower; whether there is the fault condition similar with fault point near the end that then track walker can check faulty line, this is significant for prevention relay fail when similar fault occurs protection range end.

Accompanying drawing explanation

Fig. 1 is simulating system failure equivalent structure figure;

Fig. 2 protects margin of safety meaning flow chart to show;

Safety Margin method flow diagram is protected during Fig. 3 end fault.

Embodiment

Elaborate to embodiments of the invention below, the present embodiment is implemented under premised on technical solution of the present invention, give detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

Embodiment 1

As shown in Figure 1, the present embodiment relates to a kind of protection Safety Margin method based on recorder data, and the method comprises following steps in implementation process:

1, in electric power system, fault oscillograph starts record ripple when grid collapses, when the system failure, and can the Wave data of record protection installation place electric parameters.

2, utilize recorder data, electric parameters when obtaining fault according to protection philosophy, substitute into protection act criterion determination three-stage protection setting value, I _zdfor current protection setting value, U _zdfor voltage protection setting value, Z _mimpedance relay measurement impedance;

3, because the operating characteristics of distance protection generally can be expressed as an operating space on impedance plane; only use sensitivity concept can not complete evaluation measurement impedance from the distance on each border of operating space; therefore The present invention gives the definition of protection margin of safety; for the distance of quota portray fault amount from trip boundary; thus can the margin of safety of qualitative assessment relay fail, particular content comprises:

3.1) the margin of safety S of current protection _rI, i.e. a kind of excessive protection: $S_{\mathrm{rI}}=\frac{I_k}{I_{\mathrm{zd}}{K}_{\mathrm{sr}}}---\left(1\right)$

Wherein: I _kfor fault phase electrical quantities measurement value during fault, as protected phase current or the zero-sequence current of installation place; I _zdfor protection seting value; K _srfor safety margin coefficient, general value is greater than 1; S _rIfor the margin of safety of relay fail, and work as K _srduring the coefficient of fetch protection sensitivity requirement, SrI should be greater than 1 to meet sensitivity requirement.

3.2) the margin of safety S of under-voltage protection _rV, namely a kind of amount of owing is protected: $S_{\mathrm{rV}}=\frac{U_{\mathrm{zd}}}{U_k{K}_{\mathrm{sr}}}$

$\left(2\right)$

Wherein: U _kfor fault phase electrical quantities measurement value during fault, as the phase voltage of protection safe place bus; U _zdfor protection seting value; Other parameter is with (2).Work as K _srduring the coefficient of fetch protection sensitivity requirement, S _rVshould be greater than 1, otherwise protection can not meet sensitivity requirement.

3.3) the margin of safety S of distance protection _rZ; $S_{\mathrm{rZ}}=\frac{{\mathrm{\θ}}_H-{\mathrm{\θ}}_L}{|{\mathrm{\θ}}_H+{\mathrm{\θ}}_L-2{\mathrm{\θ}}_m|\×K_{\mathrm{sr}}}---\left(3\right)$

Wherein: two vertical line represents and takes absolute value, θ _mfor the angle that fault phase impedance relay during phase formula circle characteristic impedance relay fault is measured, θ _hand θ _lbe respectively the high and low limit value of operating criterion, its operation equation is:

θ _L≤θ _m≤θ _H(4)

When measurement impedance drops in operating space, S _rZmust 1 be greater than; Work as θ _mduring the closer to the median of criterion upper lower limit value, the numerical value of margin of safety is larger, represents that this criterion is more not easy tripping.

4, the occurrence positions of physical fault is random, and possible breakdown can occur in protection range end, and when fault occurs in protection range end, for checking the adaptability of protection seting value, during end fault, the concrete determining step of three-stage protection margin of safety is as follows:

As shown in Figure 1, if faulty line is MN, two ends bus represents with M and N respectively, and position of failure point F represents, the upper level branch road of its M side is PM.

4.1) utilize faulty line both sides recorder data failure judgement type, the position of the localization of faults and transition resistance, be specially:

4.1.1) the positive sequence line impedance between fault point F to M side bus is: zero sequence line impedance between F to the M side bus of fault point is: (when fault type is phase fault, need not determine), wherein: for MN circuit positive sequence impedance;

4.1.2) each phase voltage phasor in fault point is calculated

In fault point each sequence voltage phasor and each phase voltage phasor for positive sequence voltage phasor, ${\stackrel{\·}{U}}_{2F}={\stackrel{\·}{U}}_{2M}-{\stackrel{\·}{I}}_{2M}{\stackrel{\·}{Z}}_{1\mathrm{MF}}$ For negative sequence voltage phasor;

for residual voltage phasor (when fault type is phase fault, need not determine, ), finally utilize phase/sequence transformation relation to obtain each phase voltage phasor in fault point with

4.1.3) according to fault type, localization of faults transition resistance, its type comprises:

I) single-phase earthing and when fault phase be A phase time, wherein: R _gfor the transition resistance of single phase ground fault.

Ii) line to line fault and when fault phase is BC, work as R _b=R _cfault, then ${\stackrel{\·}{I}}_{\mathrm{BF}}={\stackrel{\·}{I}}_{\mathrm{BM}}+{\stackrel{\·}{I}}_{\mathrm{BN}},R_{\mathrm{arc}}=2R_B=\frac{{\stackrel{\·}{U}}_{\mathrm{BF}}-{\stackrel{\·}{U}}_{\mathrm{CF}}}{{\stackrel{\·}{I}}_{\mathrm{BF}}},$ R _arcfor the transition resistance of phase-to phase fault.

Iii) line to line fault ground connection and when fault phase be BC, work as R _b=R _c, then $\begin{array}{c}{\stackrel{\·}{I}}_{\mathrm{BF}}={\stackrel{\·}{I}}_{\mathrm{BM}}+{\stackrel{\·}{I}}_{\mathrm{BN}},{\stackrel{\·}{I}}_{\mathrm{CF}}={\stackrel{\·}{I}}_{\mathrm{CM}}+{\stackrel{\·}{I}}_{\mathrm{CN}}\\ R_B=R_C=\frac{{\stackrel{\·}{U}}_{\mathrm{BF}}-{\stackrel{\·}{U}}_{\mathrm{CF}}}{{\stackrel{\·}{I}}_{\mathrm{BF}}-{\stackrel{\·}{I}}_{\mathrm{CF}}},R_g=\frac{{\stackrel{\·}{U}}_{\mathrm{BF}}-{\stackrel{\·}{I}}_{\mathrm{BF}}{R}_B}{{\stackrel{\·}{I}}_{\mathrm{BF}}+{\stackrel{\·}{I}}_{\mathrm{CF}}}\end{array},$ Wherein: R _gfor ground connection transition resistance, R _b, R _cfor alternate transition resistance.

Iv) three-phase shortcircuit and work as R _a=R _b=R _c, then $\begin{array}{c}{R}_A=\frac{{\stackrel{\·}{U}}_{\mathrm{AF}}}{{\stackrel{\·}{I}}_{\mathrm{AF}}},R_B=\frac{{\stackrel{\·}{U}}_{\mathrm{BF}}}{{\stackrel{\·}{I}}_{\mathrm{BF}}},R_C=\frac{{\stackrel{\·}{U}}_{\mathrm{CF}}}{{\stackrel{\·}{I}}_{\mathrm{CF}}}\\ R_A\≈R_C\≈R_C\end{array},$ Wherein: R _a, R _b, R _cfor alternate transition resistance.

4.2) calculating the system equivalent impedance of faulty line both sides and equivalent electromotive force, is A phase for order components benchmark: positive sequence is identical with negative phase-sequence system impedance, then mutually $\begin{array}{c}{Z}_{1M}=Z_{2M}=-\frac{{\stackrel{\·}{U}}_{2M}}{{\stackrel{\·}{I}}_{2M}},Z_{0M}=-\frac{{\stackrel{\·}{U}}_{0M}}{{\stackrel{\·}{I}}_{0M}}\\ Z_{1N}=N_{2N}=-\frac{{\stackrel{\·}{U}}_{2N}}{{\stackrel{\·}{I}}_{2N}},Z_{0N}=-\frac{{\stackrel{\·}{U}}_{0N}}{{\stackrel{\·}{I}}_{0N}}\\ {\stackrel{\·}{E}}_{\mathrm{AM}}={\stackrel{\·}{U}}_{1M}+{\stackrel{\·}{I}}_{1M},{\stackrel{\·}{E}}_{\mathrm{AN}}={\stackrel{\·}{U}}_{1N}+{\stackrel{\·}{I}}_{1N}{Z}_{1N}\end{array};$

When three-phase shortcircuit, both sides system impedance is determined by following formula: $\begin{array}{c}{Z}_{1M}=Z_{2M}=-\frac{{\stackrel{\·}{U}}_{1M}-{\stackrel{\·}{U}}_{\mathrm{AM}\left|0\right|}}{{\stackrel{\·}{I}}_{1M}-{\stackrel{\·}{I}}_{\mathrm{AM}\left|0\right|}}\\ Z_{1N}=Z_{2N}=-\frac{{\stackrel{\·}{U}}_{1N}-{\stackrel{\·}{U}}_{\mathrm{AN}\left|0\right|}}{{\stackrel{\·}{I}}_{1N}-{\stackrel{\·}{I}}_{\mathrm{AN}\left|0\right|}}\end{array};$

4.3) faulty line both sides electric parameters correlated branch coefficient is calculated, be specially: utilize current break metering method to judge the fault initial time of both sides recorder data, then fault phase-selecting method failure judgement type is utilized, and determine the benchmark phase of order components, recycle each phase voltage and the electric current phasor of circuit both sides after all-round or half cycle Fourier methods determination fault; Finally determine the order components of faulty line both sides voltage and current and the current branch coefficient of non-faulting branch road (the upper level branch road PM of M side) P side.

The electric current of the P side of described non-faulting branch road PM is m side electric current in the voltage and current of described faulty line MN both sides is

The current branch coefficient (benchmark of order components is A phase mutually) of the upper level branch road PM of described faulty line MN: $K_{\mathrm{fz}1P}=\frac{{\stackrel{\·}{I}}_{1P}-{\stackrel{\·}{I}}_{\mathrm{AP}\left|0\right|}}{{\stackrel{\·}{I}}_{1M}-{\stackrel{\·}{I}}_{\mathrm{AM}\left|0\right|}},K_{\mathrm{fz}2P}=\frac{{\stackrel{\·}{I}}_{2P}}{{\stackrel{\·}{I}}_{2M}},K_{\mathrm{fz}0P}=\frac{{\stackrel{\·}{I}}_{0P}}{{\stackrel{\·}{I}}_{0M}},$ Wherein: for A phase voltage before the fault of MN circuit M side, for MN circuit M side forward-order current, K _fz1P, K _fz2P, K _fz0Ppositive sequence respectively, negative phase-sequence and zero-sequence current braning factor (when fault type is ungrounded fault, zero-sequence current braning factor need not be determined).

4.4) fault mode of simulating same feature moves on to the end of MN line (i.e. N side), and recalculate the fault amount of protection installation place and upper level route protection installation place, concrete steps are as follows:

4.4.1) calculate the system synthesis impedance seen into for port with fault point and ground, positive sequence and negative phase-sequence comprehensive impedance are:

$Z_{1\mathrm{\Σ}}=Z_{2\mathrm{\Σ}}=\frac{(Z_{1M}+Z_{1\mathrm{MN}})Z_{1N}}{Z_{1M}+Z_{1\mathrm{MN}}+Z_{1N}},$ Zero sequence synthetic impedance is: $Z_{0\mathrm{\Σ}}=\frac{(Z_{0M}+Z_{0\mathrm{MN}})Z_{0N}}{Z_{0M}+Z_{0\mathrm{MN}}+Z_{0N}};$

4.4.2) faulted phase voltage and the electric current of faulty line protection installation place (M side) is calculated: for single phase ground fault, when fault phase is A phase, wherein the benchmark of order components is A phase mutually, in following formula then have:

Then M side faulted phase voltage and electric current are respectively:

4.4.3) faulted phase voltage and the electric current of non-faulting branch road (the upper level branch road PM of M side) P side is calculated, wherein for order components benchmark phase, then have wherein: K _fz1, K _fz2, K _fz0being respectively each sequence current branch coefficient, utilizing and step 4.1.2) identical phase/sequence converts and obtains each phase voltage in P side and electric current.

4.4.4) fault is calculated when MN line end (i.e. N side), the measurement impedance of MN circuit M side and PM branch road P side: for single-phase earthing and fault phase is A phase, then $Z_{\mathrm{JM}}=\frac{{\stackrel{\·}{U}}_{\mathrm{AM}}}{{\stackrel{\·}{I}}_{\mathrm{AM}}+K_{\mathrm{MN}}3{\stackrel{\·}{I}}_{0M}},Z_{\mathrm{JP}}=\frac{{\stackrel{\·}{U}}_{\mathrm{AP}}}{{\stackrel{\·}{I}}_{\mathrm{AP}}+K_{\mathrm{PM}}3{\stackrel{\·}{I}}_{0P}},$ Wherein: K _mNand K _pNbe respectively the zero-utility theory of MN and PM circuit.

5) each phase voltage of M side and P side, electric current and measurement impedance is utilized to substitute into the margin of safety determination formula of three-stage protection, the fixed value checking of M side and P side three-stage protection when can realize supposing that fault occurs in MN line end.

Technique effect:

The validity of three-stage protection margin of safety when utilizing fault recorder data to calculate end fault, key is the accuracy of calculated fault amount.Method of calibration during in order to verify described end fault, the present invention devises following emulation experiment: test system structure is as shown in Figure of description Fig. 1.The equivalent power parameter of M side system is: z _m1=Z _m2=j6.06 Ω, Z _m0=j7.22 Ω.The equivalent power parameter of N side system is: z _n1=Z _n2=j44.1 Ω, Z _n0=j79.4 Ω.

Have two loop lines (not considering to intercouple) between PM, length is all 50km, MN line length is 47.3km, and the unit length parameter of all circuits is: Z _l1=Z _l2=0.3635 ∠ 82 ° Ω/km, Z _l0=1.3630 ∠ 82 ° Ω/km.Fault point F is 20km from the distance of bus M.

Carry out fault simulation with PSCAD, protect the voltage at 1 and 2 places, current simulations data as fault recorder data.The phase voltage, phase current and the measurement impedance that utilize the method for Section 2 to calculate when fault (fault type and transition resistance are all identical) with the identical type of F point occurs MN line end (i.e. N side), to protect 1 and 3 place's fault phases.The error analysis of this result of calculation refers to table 1 to table 7.Wherein Um/Im/Zm is the error percentage of protection 1 place faulted phase voltage, electric current and measurement impedance amplitude, and AZm is the measurement impedance angular error percentage ratio of 180 (angular error and).Up/Ip/Zp/AZp is the error percentage of each fault amount in protection 3 place.In above-mentioned error analysis with the result of PSCAD fault simulation during N place fault for true value.

Table 1A phase ground connection, Rg=500 Ω (unit: %)

δ	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									30	3.0	4.7	6.2	7.1	1.3	4.2	4.3	7.1
60	2.8	2.2	4.5	3.9	1.2	2.2	2.9	3.8

Upper table analysis fault preload level is on the impact of error.Fault is A phase ground connection, and transition resistance Rg is 500 ohm, and analyzing the equivalent electromotive force differential seat angle of both sides power supply is 30 degree and 60 degree of two kinds of situations.

Table 2A phase ground connection, δ=30 ° (unit: %)

Rg	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									0	4.7	3.5	0.0	0.0	0.6	3.6	0.2	0.0
100	2.9	1.7	2.6	4.1	1.3	1.4	0.9	4.0
									500	3.0	4.7	6.2	7.1	1.3	4.2	4.3	7.1

During upper table analysis single phase ground fault, different transition resistance is on the impact of error.

Table 3BC phase fault, δ=30 ° (unit: %)

Rb	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									0	1.5	0.5	0.1	0.0	0.5	0.4	0.3	0.0
10	2.6	1.8	1.0	1.4	0.9	1.9	0.2	1.1
									20	2.9	2.7	1.8	2.2	1.2	2.7	0.4	1.9

During upper table analysis phase fault, different transition resistance is on the impact of error.Wherein Rb is the half of alternate arc resistance.

Table 4BC ground connection, δ=30 °, Rb=0 (unit: %)

Rg	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									0	0.2	0.1	0.1	0.0	0.3	0.2	0.3	0.0
100	1.2	0.7	0.1	0.0	0.4	0.6	0.3	0.0
									500	1.4	0.5	0.1	0.0	0.5	0.5	0.3	0.0

When table 4 to table 6 analyzes two-phase grounding fault, different transition resistance is on the impact of error, and wherein Rb is the half of alternate arc resistance, and Rg is ground connection transition resistance.

Table 5BC ground connection, δ=30 °, Rb=10 (unit: %)

Rg	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									0	1.5	0.5	1.0	1.4	0.7	0.5	0.2	1.1
100	2.5	1.8	1.0	1.4	0.9	1.9	0.2	1.1
									500	2.6	1.8	1.0	1.4	0.9	1.9	0.2	1.1

Table 6BC ground connection, δ=30 °, Rb=20 (unit: %)

Rg	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									0	2.1	0.7	1.8	2.2	1.0	0.7	0.4	1.9
100	2.8	2.5	1.8	2.2	1.1	2.6	0.4	1.9
									500	2.9	2.6	1.8	2.2	1.2	2.7	0.4	1.9

Table 7 three-phase shortcircuit, δ=30 ° (unit: %)

Ra	Um	Im	Zm	AZm	Up	Ip	Zp	AZp
									0	2.2	2.1	0.1	0	2.3	2.1	0.2	0
10	1.9	1.4	0.5	0.4	2.1	1.4	0.7	0.2
									20	1.4	0.7	0.7	0.5	1.8	0.7	1.1	0.4

During upper table analysis three-phase shortcircuit, different arc resistance is on the impact of error, and wherein Ra is the half of any two alternate arc resistances.

Error analysis from table 1 to table 7; when known F point breaks down under the fault recorder data at MN circuit two ends and the condition of MN and PM line parameter circuit value; the method of Section 4 can be utilized to estimate and to protect 1 and the protection voltage of 3 place's fault phases, electric current and measurement impedance when MN line end same-type fault; relative error between the estimated value of voltage, electric current and measurement impedance amplitude and actual value is no more than 10%, and the error between the estimated value of measurement impedance impedance angle and actual value is no more than 15 degree (15/180=8.3%).Therefore the verification of three-stage protection margin of safety when the fault amount utilizing the method to calculate may be used for line end fault.

In sum, the present invention is based on the check method that fault recorder data carries out protecting definite value online, considered the physical cabling of current electric grid, trend, generating and the impact on short circuit current such as load level, generator and load model during fault recorder data collection, the protection definite value of therefore adjusting based on this result can react the operational mode of current electric grid;

Electric parameters when the present invention utilizes recorder data to calculate fault according to protection philosophy, and substitute into protection act criterion, the adaptability of verification protection definite value, avoids the generation by each component models of electrical network and this situation of parameter influence;

The present invention introduces the definition of protection seting value margin of safety; because the operating characteristics of distance protection generally can be expressed as an operating space on impedance plane; only use sensitivity concept can not complete evaluation measurement impedance from the distance on each border of operating space; therefore The present invention gives the definition of protection margin of safety; for the distance of quota portray fault amount from trip boundary, thus can the margin of safety of qualitative assessment relay fail.When electrical network does not break down, and when just having larger disturbance, fault oscillograph also may start record ripple according to its start-up criterion.In this case recorder data during fault-free can be utilized to verify the margin of safety of false protection.If the margin of safety that the method utilizing the present invention to propose calculates is lower; whether there is the fault condition similar with fault point near the end that then track walker can check faulty line, when this breaks down in protection range for prevention, relay fail is significant.

Claims (8)

1., based on a protection Safety Margin method for recorder data, it is characterized in that, comprise the following steps:

1) start record ripple record recorder data when the grid collapses, electric parameters when utilizing recorder data to calculate fault according to protection philosophy, substitutes into protection act criterion and calculates protection seting value;

2) calculate protection margin of safety, specifically comprise: the margin of safety of the margin of safety of current protection, the margin of safety of under-voltage protection, distance protection;

3) whether failure judgement occurs in protection range at end, and concrete steps comprise:

3.1) utilize faulty line both sides recorder data failure judgement type, calculate position and the transition resistance of fault point;

3.2) calculate the system equivalent impedance of faulty line both sides and equivalent electromotive force, and calculate faulty line both sides electric parameters correlated branch coefficient;

3.3) simulate the fault mode of same feature, namely fault type and transition resistance move on to faulty line end, recalculate the fault amount of protection installation place and upper level route protection installation place;

Described recorder data comprises: the Wave data protecting installation place electric parameters during fault.

2. method according to claim 1, is characterized in that, the margin of safety S of described current protection _rI, be specially a kind of excessive protection: wherein: I _kfor fault phase electrical quantities measurement value during fault, as protected phase current or the zero-sequence current of installation place; I _zdfor protection seting value; K _srfor safety margin coefficient, S _rIfor the margin of safety of relay fail, and work as K _srduring the coefficient of fetch protection sensitivity requirement, S _rIbe greater than 1 to meet sensitivity requirement.

3. method according to claim 1, is characterized in that, the margin of safety S of described under-voltage protection _rV, be specially a kind of amount of owing and protect: wherein: U _kfor fault phase electrical quantities measurement value during fault, U _zdfor protection seting value; Work as K _srduring the coefficient of fetch protection sensitivity requirement, S _rVbe greater than 1 to meet sensitivity requirement.

4. method according to claim 1, is characterized in that, the margin of safety S of described distance protection _rZ, be specially wherein: two vertical line represents and takes absolute value, θ _mfor the angle that fault phase impedance relay during phase formula circle characteristic impedance relay fault is measured, θ _hand θ _lbe respectively the high and low limit value of operating criterion, its operation equation is: θ _l≤ θ _m≤ θ _h, when measurement impedance drops in operating space, S _rZmust 1 be greater than; Work as θ _mduring the closer to the median of criterion upper lower limit value, the numerical value of margin of safety is larger, represents that this criterion is more not easy tripping.

5. method according to claim 1, is characterized in that, described step 3.1, and namely utilize faulty line both sides recorder data failure judgement type, the position of the localization of faults and transition resistance, be specially:

1) the positive sequence line impedance between fault point F to M side bus is: zero sequence line impedance between F to the M side bus of fault point is: wherein: for MN circuit positive sequence impedance;

2) each phase voltage phasor in fault point is calculated in fault point each sequence voltage phasor and each phase voltage phasor for positive sequence voltage phasor, for negative sequence voltage phasor;

for residual voltage phasor, phase/sequence transformation relation is finally utilized to obtain each phase voltage phasor in fault point with

3) according to fault type, localization of faults transition resistance, its type comprises:

I) single-phase earthing and when fault phase be A phase time, wherein: R _gfor the transition resistance of single phase ground fault;

Ii) line to line fault and when fault phase is BC, work as R _b=R _cfault, then

r _arcfor the transition resistance of phase-to phase fault;

Iii) line to line fault ground connection and when fault phase be BC, work as R _b=R _c, then

wherein: R _gfor ground connection transition resistance, R _b, R _cfor alternate transition resistance;

Iv) three-phase shortcircuit and work as R _a=R _b=R _c, then wherein: R _a, R _b, R _cfor alternate transition resistance.

6. method according to claim 1, is characterized in that, described step 3.2) in, calculate the system equivalent impedance of faulty line both sides and equivalent electromotive force, when order components benchmark is A phase mutually, when namely positive sequence is identical with negative phase-sequence system impedance, then

When three-phase shortcircuit, both sides system impedance is determined by following formula: .

7. method according to claim 1, it is characterized in that, described step 3.2) in, calculate faulty line both sides electric parameters correlated branch coefficient, be specially: utilize current break metering method to judge the fault initial time of both sides recorder data, then utilize fault phase-selecting method failure judgement type, and determine the benchmark phase of order components, recycle each phase voltage and the electric current phasor of circuit both sides after all-round or half cycle Fourier methods determination fault; Finally determine order components and the non-faulting branch road of faulty line both sides voltage and current, i.e. the current branch coefficient of the P side of the upper level branch road PM of M side, wherein the electric current of the P side of non-faulting branch road PM is m side electric current in the voltage and current of faulty line MN both sides is

When the benchmark of order components is A phase time mutually, the current branch coefficient of the upper level branch road PM of described faulty line MN: wherein: for A phase voltage before the fault of MN circuit M side, for MN circuit M side forward-order current, K _fz1P, K _fz2P, K _fz0Ppositive sequence, negative phase-sequence and zero-sequence current braning factor respectively.

8. method according to claim 1, is characterized in that, described step 3.3); the fault mode of namely simulating same feature moves on to the end of MN line; i.e. N side, recalculate the fault amount of protection installation place and upper level route protection installation place, concrete steps are as follows:

1) calculate the system synthesis impedance seen into for port with fault point and ground, positive sequence and negative phase-sequence comprehensive impedance are:

zero sequence synthetic impedance is:

2) faulted phase voltage and the electric current of faulty line protection installation place (M side) is calculated: for single phase ground fault, when fault phase is A phase, wherein the benchmark of order components is A phase mutually, in following formula then have:

Then M side faulted phase voltage and electric current are respectively:

3) faulted phase voltage and the electric current of non-faulting branch road (the upper level branch road PM of M side) P side is calculated, wherein for order components benchmark phase, then have wherein: K _fz1, K _fz2, K _fz0being respectively each sequence current branch coefficient, utilizing and step 4.1.2) identical phase/sequence converts and obtains each phase voltage in P side and electric current;

4) fault is calculated when MN line end (i.e. N side), the measurement impedance of MN circuit M side and PM branch road P side: for single-phase earthing and fault phase is A phase, then wherein: K _mNand K _pNbe respectively the zero-utility theory of MN and PM circuit;

5) each phase voltage of M side and P side, electric current and measurement impedance is utilized to substitute into the margin of safety determination formula of three-stage protection, the fixed value checking of M side and P side three-stage protection when can realize supposing that fault occurs in MN line end.