CN102324722A - Current differential protection method based on fault component current amplitudes and phase differences - Google Patents
Current differential protection method based on fault component current amplitudes and phase differences Download PDFInfo
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- CN102324722A CN102324722A CN201110266262A CN201110266262A CN102324722A CN 102324722 A CN102324722 A CN 102324722A CN 201110266262 A CN201110266262 A CN 201110266262A CN 201110266262 A CN201110266262 A CN 201110266262A CN 102324722 A CN102324722 A CN 102324722A
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Abstract
The invention relates to a current differential protection method based on fault component current amplitudes and phase differences. The current differential protection method is characterized in that: a differential protection criterion is formed by the adoption of the current fault component amplitudes at two sides of a protected line and the phase differences at the two sides of the protected line, wherein the differential current value (Icd) is equal to the sum of the current fault component amplitude (the absolute value of [delta]IM) at one side and the product of the current fault component amplitude (the absolute value of [delta]IN) at the opposite side and a cosine function of the phase difference ([phi]) between the absolute value of [delta]IM and the absolute value of [delta]IN, i.e. Icd= (the absolute value of [delta]IM)+(the absolute value of [delta]IN)cos[phi]; and the braking current (Ir) is equal to the difference between the absolute value of [delta]IM and the product of the absolute value of [delta]IN and the cos[phi], i.e. Ir= (the absolute value of [delta]IM)-(the absolute value of [delta]IN)cos[phi], and the differential protection criterion is the following inequation: Icd-KIr=> Idz, wherein K is a braking coefficient and Idz is an action current threshold. If the differential protection criterion is satisfied, an internal fault is determined and the differential protection acts; if the differential protection criterion is not satisfied, an external fault is determined and the differential protection does not act. The current differential protection method related to the invention has the advantages of higher sensitivity for internal faults, higher safety for external faults, fewer effects subjected from the factors, such as the transition resistance, the distributed capacitance, the TA saturation and the like, and good performances.
Description
Technical field
The present invention relates to a kind of current differential protection method of field of relay protection in power, especially a kind of current differential protection method based on fault component current amplitude and phase difference.
Background technology
The current differential protection principle realizes according to Kirchhoff's first law whether the electric current that flows into, flows out protected object through calculating equates, thereby judge whether protected object internal fault has taken place.The current differential protection principle has the ability of stronger extraction internal fault information, and need not voltage, in electric power system, has obtained extensive use, and most equipment and circuit all preferentially adopt current differential protection as main protection.Difference according to the employing electric current; Current differential protection can be divided into total current differential protection principle, current failure component differential protection principle, Zero sequence current differential protection principle, current phase differential protecting principle etc.; Wherein, total current is differential uses comparatively extensive with current failure component differential protection principle.
The current differential protection performance is subject to the influence of unsymmetrical current.The source of unsymmetrical current is more in electric power system, like capacitance current, each measurement point non-synchronous sampling, the TA characteristic is inconsistent, TA is saturated etc.For overcoming the influence of unsymmetrical current to differential protection, introduced stalling current and ratio restraint coefficient, but the existence of braking amount can influence the sensitivity of differential protection conversely again, it is not enough to cause taking place under some situation inside sensitivity when high resistance earthing fault.Therefore adopt which amount to constitute differential and stalling current, and then constitute the comparatively desirable current differential protection criterion of operating characteristics, become the key issue of research current differential protection.
Fault current component have do not receive that load current influences, sensitivity is than characteristics such as height; Receive people's generally attention; The phasor differential protection that constitutes based on fault current component has higher sensitivity and reliability than total current phasor differential protection; But still can tripping when the troubles inside the sample space that takes place under some operational mode through the great transition grounding through resistance, the big and TA of line distribution capacitance is serious external area error takes place when saturated still maybe malfunction.
One Chinese patent application 200910022923 discloses a kind of current differential protection of direct current electric transmission line algorithm; This method is according to the Transmission Line Distributed Parameter model; In time domain, utilize modular transformation to convert the sampled value of direct current, direct voltage into modulus; Utilize two ends mode voltage, galvanometer to calculate each mould electric current constantly of circuit point then respectively from the circuit two ends; Directly construct the current differential protection criterion with the mould electric current, perhaps through the synthetic electrode current of utmost point mould inverse transformation, again according to electrode current structure current differential protection criterion.This invention because employing is distributed parameter transmission line model, therefore requires system to have very high sample frequency only to the DC power transmission line in the electric power system.Introduce phase-model transformation and inverse transformation in addition and also increased amount of calculation.
One Chinese patent application 201010034085 discloses a kind of inner steady-state quantity of transformer and the compound current differential protection method and compound current differential relay of fault component of being used for.Relay in this method adopts steady-state quantity computer differential electric current and stalling current to constitute the two K differential relays of a steady-state quantity; Adopt fault component computer differential electric current and stalling current to constitute the two K differential relays of another fault component, then both are synthesized the compound current differential relay of steady-state quantities and fault component.This invention relates to is transformer differential protection but not line differential protection, adopts a plurality of restraint coefficients to make to adjust to calculate to become complicated.
One Chinese patent application 201010165606 discloses a kind of phase relevant current differential protection method.Circuital phase relevant current differential protection criterion is adopted in this invention; Basic principle is exactly that the current and phase difference of differential circuit both sides is introduced the current differential criterion; Make the braking Xiang Zaiqu internal and external fault time-division in the criterion not be presented as driving and braking two states, and propose four kinds of realization criterions and computational methods.This invention is compared conventional method and is being improved a lot aspect fault judgement reliability and the sensitivity, but has much room for improvement in the performance aspect the reply unsymmetrical current.
Summary of the invention
The objective of the invention is for overcoming the deficiency of above-mentioned prior art; A kind of current differential protection method based on fault component current amplitude and phase difference is provided; This method does not receive that load current influences, criterion is highly sensitive, has the ability of good differentiation district internal and external fault; Stalling current when troubles inside the sample space is very little; Can improve differential protection and judge the sensitivity of troubles inside the sample space, the differential current when external area error is very little, can improve the fail safe that differential protection is judged external area error; Receive distributed capacitance, influence that TA is saturated less, anti-transition resistance ability is stronger.
For realizing above-mentioned purpose, the present invention adopts following technical proposals:
A kind of current differential protection method based on fault component current amplitude and phase difference may further comprise the steps:
The first step: after fault took place, the current value after the circuit both sides take place with fault respectively deducted the current value before fault takes place, and adopts Fourier algorithm can obtain the amplitude and the phase place of current failure component then;
Second step: make differential current (I
Cd) equal this side current failure component amplitude | Δ I
M| add offside current failure component amplitude | Δ I
N| with the two phase difference
The product of cosine function, promptly
Stalling current (I
r) equal | Δ I
M| deduct | Δ I
N| with
Product, promptly
The 3rd step: the differential protection criterion is I
Cd-KI
r>=I
Dz, wherein K is a restraint coefficient, I
DzBe the operating current threshold value.If satisfy the differential protection criterion, be judged to troubles inside the sample space, the differential protection action, otherwise be external area error, differential protection is failure to actuate.
The computational methods of the current failure component in the described first step are: the current value after taking place with fault deducts the current value that fault takes place by the previous cycle, to obtain the current failure component value that fault takes place by a plurality of cycles of back.
Differential current in described second step constitutes expression formula and does
Stalling current constitutes expression formula
Wherein | Δ I
M| be the amplitude of this side current failure component, | Δ I
N| be the amplitude of offside current failure component,
Cosine value for phase difference between the current failure component of both sides.
Differential protection criterion in described the 3rd step is I
Cd-KI
r>=I
Dz, wherein K is a restraint coefficient, span is between 0.5～0.8, I
DzBe the operating current threshold value, adjust by the maximum imbalance current of the system of escaping.If satisfy the differential protection criterion, be judged to troubles inside the sample space, the differential protection action, otherwise be judged to external area error, differential protection is failure to actuate.
The present invention adopts the amplitude of current failure component and phase difference to constitute the differential protection criterion, has following advantage with existing similar compared with techniques:
1. adopt the failure of the current component to constitute criterion, have advantages such as not receiving load current influences, criterion sensitivity height;
2. current failure component phase difference does not receive the influence of load current and transition resistance, receives distributed capacitance, influence that TA is saturated less, only by the impedance angle decision of the comprehensive impedance of fault point two side systems, has the ability of good differentiation district internal and external fault;
3. the stalling current of criterion that the present invention carries when troubles inside the sample space is very little; Can improve differential protection and judge the sensitivity of troubles inside the sample space; Differential current when external area error is very little; Can improve differential protection and judge the fail safe of external area error, receive distributed capacitance, influence that TA is saturated less, anti-transition resistance ability is stronger.
Description of drawings
Fig. 1 is two ends power system model structural representations;
Fig. 2 is differential current and the braking current curve sketch map during the F1 point failure in the district;
Fig. 3 is a new criterion according to the invention and traditional criterion operating current comparison sketch map during the F1 point failure in the district;
Differential current and braking current curve sketch map when Fig. 4 is the outer F2 point failure in district;
New criterion according to the invention and traditional criterion operating current comparison sketch map when Fig. 5 is the outer F2 point failure in district;
Fig. 6 is district outer F2 point failure and TA new criterion according to the invention and traditional criterion operating current comparison sketch map when saturated.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is further specified.
1. current differential protection criterion performance evaluation during troubles inside the sample space
In both-end power system model shown in Figure 1; F1 point in the protection zone is provided with A phase metallic earthing fault; Differential current designed according to this invention and stalling current computational methods; Obtain differential, braking current curve is as shown in Figure 2, wherein solid line is represented stalling current, dotted line is represented differential current.When internal fault took place, differential current was much larger than stalling current.For the superiority of criterion according to the invention is described, compare with current change quantity differential criterion (traditional criterion) performance commonly used at present.The comparable situation of the two operating current curve is as shown in Figure 3 during F1 place fault.It is thus clear that when the generating region internal fault, the operating current of criterion that the present invention carries is greater than the operating current of traditional criterion, show that criterion that the present invention carries compares with traditional criterion when troubles inside the sample space, have higher sensitivity.
2. current differential protection criterion performance evaluation during external area error
The F2 place is provided with A phase metallic earthing fault outside the protection zone, and the differential current and the braking current curve of criterion that the present invention carries are as shown in Figure 4, and this moment, differential current was very little and stalling current is very big.Corresponding action current curve and traditional criterion operating current curve comparable situation are as shown in Figure 5.It is thus clear that when external area error took place, the operating current of criterion that the present invention carries was less than the operating current of traditional criterion, show that criterion that the present invention carries compares with traditional criterion when external area error, have higher fail safe.
3. current differential protection criterion performance evaluation when external area error and TA are saturated
Be located at that the F2 place breaks down and left side TA is saturated, the comparable situation of the operating current curve of criterion that the present invention carries and traditional criterion operating current curve is as shown in Figure 6.Compare with situation 2 this moment, and the operating current of the two all has reducing in various degree, but the operating current of criterion that the present invention carries shows that still less than the operating current of traditional criterion criterion that the present invention in this case carries still has higher fail safe.
Claims (1)
1. the current differential protection method based on fault component current amplitude and phase difference is characterized in that, may further comprise the steps:
The first step: after fault took place, the current value after the circuit both sides take place with fault respectively deducted the current value that fault takes place by the previous cycle, adopts Fourier algorithm to obtain the amplitude and the phase place of circuit both sides current failure component then;
Second step: make differential current (I
Cd) equal the amplitude of this side current failure component | Δ I
M| add the amplitude of offside current failure component | Δ I
N| and phase difference between the current failure component of circuit both sides
The product of cosine function, promptly
Stalling current (I
r) equal | Δ I
M| deduct | Δ I
N| with
Product, promptly
The 3rd step: the differential protection criterion is I
Cd-KI
r>=I
Dz, wherein K is a restraint coefficient, span is between 0.5～0.8, I
DzBe the operating current threshold value, adjust,, be judged to troubles inside the sample space if satisfy the differential protection criterion by the maximum imbalance current of the system of escaping, the differential protection action, otherwise be judged to external area error, differential protection is failure to actuate.
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|---|---|---|---|
| CN201110266262.9A CN102324722B (en) | 2011-09-08 | 2011-09-08 | Current differential protection method based on fault component current amplitudes and phase differences |
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|---|---|---|---|
| CN201110266262.9A CN102324722B (en) | 2011-09-08 | 2011-09-08 | Current differential protection method based on fault component current amplitudes and phase differences |
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| CN102324722A true CN102324722A (en) | 2012-01-18 |
| CN102324722B CN102324722B (en) | 2014-06-04 |
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Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102904227A (en) * | 2012-09-29 | 2013-01-30 | 天津大学 | Six-sequence component-based double circuit lines on same pole phase difference protection method |
| CN103346540A (en) * | 2013-03-25 | 2013-10-09 | 浙江大学 | Mixed line travelling wave differential motion protection method employing phase current braking |
| CN103746335A (en) * | 2013-12-23 | 2014-04-23 | 北京四方继保自动化股份有限公司 | Amplitude comparison principle-based relay protection method |
| CN104242268A (en) * | 2014-09-11 | 2014-12-24 | 国电南瑞科技股份有限公司 | Three-area current differential protection method |
| CN104377668A (en) * | 2014-11-21 | 2015-02-25 | 三峡大学 | Line current differential protection method based on secondary data conversion |
| CN105244860A (en) * | 2015-10-10 | 2016-01-13 | 国家电网公司 | Positive sequence admittance-based differential protection method |
| CN106356822A (en) * | 2016-10-10 | 2017-01-25 | 许继集团有限公司 | Underreach combined type protection method and device for semi-wavelength power transmission line |
| WO2017128631A1 (en) * | 2016-01-29 | 2017-08-03 | 中国电力科学研究院 | Current differential protection method for self-adaptive half-wavelength line based on time-difference method |
| CN107359602A (en) * | 2017-08-29 | 2017-11-17 | 山东大学 | A kind of motor synchronizing current comparison pilot protection method suitable for transmission line of electricity |
| CN108879622A (en) * | 2018-06-13 | 2018-11-23 | 国网浙江省电力有限公司电力科学研究院 | Distribution protection method and system based on compound ratio amplitude differential criterion |
| CN111512512A (en) * | 2017-12-20 | 2020-08-07 | Abb电网瑞士股份公司 | Phase selection for multi-terminal measurements using transmission lines |
| CN113671315A (en) * | 2021-08-18 | 2021-11-19 | 北京四方继保工程技术有限公司 | ITn power supply insulation fault positioning method based on proportional differential principle |
| CN113945858A (en) * | 2021-02-02 | 2022-01-18 | 保定钰鑫电气科技有限公司 | Three-phase non-effective grounding power supply system convenient for processing single-phase grounding fault |
| CN114221307A (en) * | 2021-12-09 | 2022-03-22 | 南京南瑞继保电气有限公司 | Line differential protection braking coefficient adjusting method and device and electronic equipment |
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| CN102904227A (en) * | 2012-09-29 | 2013-01-30 | 天津大学 | Six-sequence component-based double circuit lines on same pole phase difference protection method |
| CN103346540A (en) * | 2013-03-25 | 2013-10-09 | 浙江大学 | Mixed line travelling wave differential motion protection method employing phase current braking |
| CN103346540B (en) * | 2013-03-25 | 2016-04-27 | 浙江大学 | A kind of hybrid line traveling wave differential protecting method adopting phase current to brake |
| CN103746335A (en) * | 2013-12-23 | 2014-04-23 | 北京四方继保自动化股份有限公司 | Amplitude comparison principle-based relay protection method |
| CN103746335B (en) * | 2013-12-23 | 2017-03-29 | 北京四方继保自动化股份有限公司 | Relay protecting method based on amplitude com parison principle |
| CN104242268A (en) * | 2014-09-11 | 2014-12-24 | 国电南瑞科技股份有限公司 | Three-area current differential protection method |
| WO2016037547A1 (en) * | 2014-09-11 | 2016-03-17 | 国电南瑞科技股份有限公司 | Three-region current differential protection method |
| CN104242268B (en) * | 2014-09-11 | 2017-06-16 | 国电南瑞科技股份有限公司 | A kind of three zone current differential protecting methods |
| CN104377668A (en) * | 2014-11-21 | 2015-02-25 | 三峡大学 | Line current differential protection method based on secondary data conversion |
| CN104377668B (en) * | 2014-11-21 | 2017-08-01 | 三峡大学 | A kind of Line Current Differential Protection method converted based on secondary data |
| CN105244860A (en) * | 2015-10-10 | 2016-01-13 | 国家电网公司 | Positive sequence admittance-based differential protection method |
| CN105244860B (en) * | 2015-10-10 | 2018-02-16 | 国家电网公司 | A kind of differential protecting method based on positive sequence admittance |
| WO2017128631A1 (en) * | 2016-01-29 | 2017-08-03 | 中国电力科学研究院 | Current differential protection method for self-adaptive half-wavelength line based on time-difference method |
| US10985547B2 (en) | 2016-01-29 | 2021-04-20 | China Electric Power Research Institute Company Limited | Current differential protection method for self-adaptive half-wavelength line based on time-difference method |
| CN106356822B (en) * | 2016-10-10 | 2019-02-05 | 许继集团有限公司 | A kind of deficient range combinations formula guard method of half-wave power transmission route and device |
| CN106356822A (en) * | 2016-10-10 | 2017-01-25 | 许继集团有限公司 | Underreach combined type protection method and device for semi-wavelength power transmission line |
| CN107359602B (en) * | 2017-08-29 | 2019-02-01 | 山东大学 | A kind of motor synchronizing current comparison pilot protection method suitable for transmission line of electricity |
| CN107359602A (en) * | 2017-08-29 | 2017-11-17 | 山东大学 | A kind of motor synchronizing current comparison pilot protection method suitable for transmission line of electricity |
| CN111512512A (en) * | 2017-12-20 | 2020-08-07 | Abb电网瑞士股份公司 | Phase selection for multi-terminal measurements using transmission lines |
| CN111512512B (en) * | 2017-12-20 | 2021-07-30 | Abb电网瑞士股份公司 | Phase selection for multi-terminal measurements using transmission lines |
| US11280824B2 (en) | 2017-12-20 | 2022-03-22 | Hitachi Energy Switzerland Ag | High sensitive phase selection method |
| CN108879622A (en) * | 2018-06-13 | 2018-11-23 | 国网浙江省电力有限公司电力科学研究院 | Distribution protection method and system based on compound ratio amplitude differential criterion |
| CN113945858A (en) * | 2021-02-02 | 2022-01-18 | 保定钰鑫电气科技有限公司 | Three-phase non-effective grounding power supply system convenient for processing single-phase grounding fault |
| CN113945858B (en) * | 2021-02-02 | 2024-03-01 | 保定钰鑫电气科技有限公司 | Three-phase non-effective grounding power supply system convenient for processing single-phase grounding fault |
| CN113671315A (en) * | 2021-08-18 | 2021-11-19 | 北京四方继保工程技术有限公司 | ITn power supply insulation fault positioning method based on proportional differential principle |
| CN113671315B (en) * | 2021-08-18 | 2023-10-27 | 北京四方继保工程技术有限公司 | ITn power supply insulation fault positioning method based on proportional differential principle |
| CN114221307A (en) * | 2021-12-09 | 2022-03-22 | 南京南瑞继保电气有限公司 | Line differential protection braking coefficient adjusting method and device and electronic equipment |
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