CN104362600A - New energy based integrated configuration method for alternating current transmission line unit protection - Google Patents
New energy based integrated configuration method for alternating current transmission line unit protection Download PDFInfo
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Abstract
The invention discloses a new energy based integrated configuration method for alternating current transmission line unit protection. The method mainly includes: performing qualitative judgment on operating conditions of a line by utilizing electrical sampled data collected in each phase on two sides of the line; respectively starting longitudinal impedance of different forms according to a conclusion made by qualitative judgment; when the transmission line makes increment of corresponding current to be measured effectively, starting a corresponding longitudinal impedance algorithm and determining whether internal fault happens to the line or not according to longitudinal impedance results. The integrated configuration method for ultrahigh-voltage alternating current transmission line unit protection can overcome the defects of weak anti-jamming capability, low reliability, poor safety and the like in the prior art, and has the advantages of high anti-jamming capability, high reliability and good safety.
Description
Technical field
The present invention relates to the technical field of electric power system ultrahigh-voltage alternating-current relay protection of transmission line, particularly, relate to the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line.
Background technology
As everyone knows, under the environment of world today's energy flood tide consumption, new-energy grid-connected technology is effective New Measure of a kind of alternative conventional electric power generation that domestic and international electric power system extensively adopts, energy-saving and emission-reduction, and wherein wind power generation occupies maximum quota; But the Protection Technology of existing new-energy grid-connected ultrahigh-voltage alternating-current used transmission line also exists adaptive system and runs narrower, the sensitive discovery of fault of excursion and disturbance and reliably filter the technical barrier that difficulty coordinates etc.In view of the requirement of intelligent grid height power supply reliability; the fault discrimination capabilities improving transmission line has important economic worth and engineering potentiality, and the research wherein with the round-the-clock protection of integrated configuration of nature of trouble recognition function and wide region adaptation operational mode is particularly important.
At present, the collocation method of the modular protection in existing transmission line of alternation current can be divided into based on the electric current phasor differential protection of power frequency full dose and power frequency fault component, direction ratio compared with pilot protection, a few types such as distance pilot protection and the differential pilot protection of phase place etc.
Electric current phasor differential protection mainly utilizes the first current law of kirchhoff and correlated characteristic thereof to realize effective identification of normal operation and troubles inside the sample space.But assist carry out adjusting of Protection parameters owing to being difficult to be built with the circuit model that is beneficial to protective value analysis and lacking reasonable approach; and be determined as non-internal fault according to being subject to the impact of many disturbing factors when actual motion and therefore there are problems; such as load component (current differential protection mainly for full dose), line distribution capacitance, TA progress of disease error, TA are saturated, circuit two ends clock jitter etc., and these problems all will have a strong impact on the performance of current differential protection.
Direction ratio compared with pilot protection mainly with the phase place of same measurement point voltage for reference; obtain the directional information of fault origination point and this measurement point represented by electric current relative phase; be sent to circuit opposite end, as both sides are all designated as positive direction, then the modular protected mode that therefore can simultaneously trip.The maximum feature of this protection is that amount of communication data used is less and do not need circuit two ends synchronized sampling, but can affect the accuracy of its discriminating direction when voltage has big difference with the ratio of current values.
Distance pilot protection mainly utilizes three segment distance protections to be start unit, two segment distance protections are direction criterion, takes into account distance protection and modular protection double effects, reaches the object simplifying relaying configuration.It is the same compared with pilot protection with direction ratio does not need synchronized sampling and amount of communication data is little, but there is Coupling Between Phases compensates difficulty, the scabrous technical problems such as peer-to-peer system and fault resstance interference thereof.
The differential pilot protection of phase place mainly make use of the phase information of electric current phasor differential protection, reduces the demand of original protection to the traffic, special in taking the phase information of combination current, is more conducive to the state information of stable phase angle.But owing to only taking the phase information of electric current phasor, the excessive initiation protection exception of phase deviation can be caused when meeting the disturbing factor that above-mentioned all electric current phasor differential protection is mentioned.
Due to traditional relaying protection generally adopt identical character, there is the possible electric parameter of changing role each other and not only formed the relevant action element of protection but also the restriction threshold as same protection; may be there is the chance of phase co-conversion in action element and restriction threshold viewed from physical model when condition changes; viewed from numerical relation, they comprise the risk that size is each other put upside down equally, and viewed from protected effect, they either party all can have a strong impact on the performance of protection when deviate from regime values.Therefore, reasonable disposition protection just needs to guarantee that protective value clearly can have enough reliabilities and screen nargin completely from physical model.
Realizing in process of the present invention, inventor finds at least to exist in prior art that antijamming capability is weak, reliability is low and the defect such as poor stability.
Summary of the invention
The object of the invention is to, for the problems referred to above, propose a kind of integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected, to realize the advantage that antijamming capability is strong, reliability is high and fail safe is good.
For achieving the above object, the technical solution used in the present invention is: a kind of integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected, mainly comprises:
A, the current data utilizing each phase acquisition in circuit both sides to arrive, qualitatively judge the running status of circuit immediately;
B, carry out qualitatively judging made conclusion according to step a, start multi-form longitudinal impedance respectively; When transmission line impels the increment of above-mentioned phase induced current effectively to measure for some reason, namely can start corresponding longitudinal impedance algorithm and whether occur internal fault according to the result determination circuit of longitudinal impedance.
Further, described step a, specifically comprises:
Utilize the sampled value fault component electric current of each phase in circuit both sides
power frequency fault component electric current
and power frequency full dose electric current
immediately the qualitative judgement to circuit running status is obtained according to the size of each phase measured current calculating amplitude;
Wherein,
m, n are circuit two ends electric measurement point.
Further, described step b, specifically comprises:
B1, when the electric current of circuit both sides sampled value fault component with when meeting the startup threshold of the state of emergency, sampled value fault component integration/the accumulative and formula longitudinal impedance of specified time can be started thus; The integration of sampled value fault component/accumulative and formula longitudinal impedance are mainly used in the short trouble screening protection exit place big current;
B2, when circuit both sides power frequency fault component electric current and meet stable obtain basic measured value time, conventional power frequency fault component longitudinal impedance can be started thus;
B3, when the specified time of circuit both sides or the power frequency fault component current differential integrating meter formula of inverse time lag meet relevant start threshold time, power frequency fault component integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag can be started equally;
B4, to protect in support, need use one to definite time-lag or the power frequency full dose current differential integrating meter formula of inverse time lag, when it reach start threshold time, power frequency full dose integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag can be started.
Further, described step b1, specifically comprises:
When the electric current of circuit both sides sampled value fault component is with satisfied:
Wherein, I '
set=0.1A is the current data that line current instrument transformer secondary side measures gained sampled value; T '=5ms is the time of integration of sampled value current differential; M is that sampled data corresponding within the time of integration is counted; K
1for being greater than the integer of 1, for screening the safety factor of the state of emergency; The start unit that formula (1) is protected can be become, namely can start sampled value fault component integration/the accumulative and formula longitudinal impedance of specified time:
In formula,
for the voltage difference of the sampled value fault component that circuit two ends compensate through residual voltage;
the each phase voltage of sampled value for circuit both sides;
the each phase current of sampled value for circuit both sides; u
0m(t), u
0nt sampled value residual voltage that () is circuit both sides; r
m, r
0for mutual resistance, the zero sequence resistance of unit length circuit; F (rD) is circuit series impedance and relevant calculated value thereof; RD is total track length series resistance.
Further, described step b2, specifically comprises:
When the electric current of circuit both sides power frequency fault component is with satisfied:
Wherein, I
set=0.1A is line current instrument transformer secondary side gained power current data, can become the start unit that formula (2) is protected, and namely can start conventional power frequency fault component longitudinal impedance:
In formula,
for the voltage difference of the power frequency fault component that circuit two ends compensate through residual voltage;
for each phase power-frequency voltage fault component of circuit both sides;
for each phase power current fault component of circuit both sides;
for the residual voltage of circuit both sides; z
m, z
0for mutual impedance, the zero sequence impedance of unit length circuit; ZD is total track length series impedance.
Further, described step b4, specifically comprises:
As long as the specified time of circuit both sides or the power frequency fault component current differential integrating meter formula of inverse time lag meet:
Wherein, I '
setfor the minimum setting value of power frequency fault component current differential integral and calculating; T=20ms is the power frequency component cycle; the start unit that formula (3) is protected can be become equally, namely can start power frequency fault component integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag:
In formula, n be greater than 1 integer; T=20ms is the power frequency component cycle.
Further, described step b4, specifically also comprises:
Increase a specified time or the power frequency full dose current differential integrating meter formula of inverse time lag:
Wherein, I "
setfor the minimum setting value of power frequency full dose current differential integral and calculating, the start unit that formula (4) is protected can be become equally, namely can start power frequency full dose integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag;
This kind of impedance algorithms can be started by start unit, also can not need to start, automatically the running status of continuous long-term Real-Time Monitoring circuit:
In formula,
for the voltage difference of the power frequency full dose that circuit two ends compensate through residual voltage;
for each phase power-frequency voltage full dose of circuit both sides;
for each phase power current full dose of circuit both sides; K
loadthe weighting Reliability factor that ≈ 2 ~ 3 affects for load component, n ' is for being not less than the integer of n.
The integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected of various embodiments of the present invention, owing to mainly comprising: the current data utilizing each phase acquisition in circuit both sides to arrive, qualitatively judges the running status of circuit immediately; Qualitatively judging made conclusion according to carrying out, starting multi-form longitudinal impedance respectively; When transmission line impels the increment of above-mentioned phase induced current effectively to measure for some reason, namely can start corresponding longitudinal impedance algorithm and whether occur internal fault according to the result determination circuit of longitudinal impedance; The performance that the modular relaying protection of existing transmission line can be avoided because of various disturbing factor to reduce protection even threatens the reliability of protection, improves transmission line further and adapts to different running method, improves sensitivity and the reliability of Fault Identification criterion; Thus can overcome in prior art that antijamming capability is weak, reliability is low and the defect of poor stability, to realize the advantage that antijamming capability is strong, reliability is high and fail safe is good.
Other features and advantages of the present invention will be set forth in the following description, and, partly become apparent from specification, or understand by implementing the present invention.
Below by drawings and Examples, technical scheme of the present invention is described in further detail.
Accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for specification, together with embodiments of the present invention for explaining the present invention, is not construed as limiting the invention.In the accompanying drawings:
Fig. 1 is the three-phase line model of sampled value fault component in the present invention;
Fig. 2 is the three-phase line model of power frequency fault component in the present invention;
Fig. 3 is the three-phase line model of power frequency full dose in the present invention;
Fig. 4 is the three-phase line simplified model (three-phase is balance) of power frequency load component in the present invention;
Fig. 5 reflects by longitudinal impedance algorithm each in the present invention the corresponding relation figure of delay time and action threshold.
Embodiment
Below in conjunction with accompanying drawing, the preferred embodiments of the present invention are described, should be appreciated that preferred embodiment described herein is only for instruction and explanation of the present invention, is not intended to limit the present invention.
According to the embodiment of the present invention; as Figure 1-Figure 5; provide a kind of integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected; this concrete grammar relates to the combination new method longitudinal impedance algorithm taken various forms being applied to the examination of complicated running environment nature of trouble; the performance that the modular relaying protection of existing transmission line can be avoided because of various disturbing factor to reduce protection even threatens the reliability of protection; further raising transmission line adapts to different running method, improves sensitivity and the reliability of Fault Identification criterion.
Technical scheme of the present invention; the difference of screening in operational mode and state according to new-energy grid-connected and conventional electric power generation; by the initial value of measurement circuitry two ends electric current; the qualitative discrimination state of affairs is to the preliminary conclusion of systematic influence degree; start corresponding longitudinal impedance algorithm and according to the results of calculation of different longitudinal impedance algorithm, determine that circuit real-time running state is different from the Preservation tactics of normality.The key step of technical solution of the present invention is: first, when the electric state involved by circuit change for some reason and by the sampled value fault component electric current of each phase in Quick Acquisition circuit both sides, power frequency fault component electric current and power frequency full dose electric current, be immediately in a state of emergency according to the qualitative division circuit of calculating amplitude size of each phase measured current, general state, microvariations state and mild state; Secondly, on the basis of above-mentioned qualitative analysis conclusion, adopt multi-form longitudinal impedance algorithm respectively, calculate to phase-splitting the result of longitudinal impedance, and screen the actual nature of state according to acquired results.When computing impedance meets criterion, be sensitively judged to internal fault, can trip signal be sent; Otherwise, be reliably judged to non-internal fault, can guarantee that administered protected transmission line still can keep the state of original stable operation thus.
Technical scheme of the present invention, specifically comprises the following steps:
Step 1: the current data utilizing each phase acquisition in circuit both sides to arrive, qualitatively judges the running status of circuit immediately.
Such as, the sampled value fault component electric current of each phase in circuit both sides is utilized
power frequency fault component electric current
and power frequency full dose electric current
(wherein
m, n are circuit two ends electric measurement point), immediately obtain the qualitative judgement to circuit running status according to the size of each phase measured current calculating amplitude.
When any Status Change appears in transmission line, all cause the change of line current; That is, when the running status of transmission line changes, all can be reflected in the change of line current.Can tentatively judge that circuit is in a state of emergency, general state, microvariations state and mild state according to the size of above-mentioned current increment, be subsequent treatment and do necessary preparation.
Step 2: the conclusion made according to above-mentioned qualitative analysis, starts multi-form longitudinal impedance respectively.When transmission line impels the increment of above-mentioned phase induced current effectively to measure for some reason, namely can start corresponding longitudinal impedance algorithm and whether occur internal fault according to the result determination circuit of longitudinal impedance.
(1) when the electric current of circuit both sides sampled value fault component with when meeting the startup threshold of the state of emergency; Sampled value fault component integration/the accumulative and formula longitudinal impedance of specified time can be started thus.The integration of sampled value fault component/accumulative and formula longitudinal impedance are mainly used in the short trouble screening protection exit place big current, are one of important evidence of innovating of the present invention.
Such as, when the electric current of circuit both sides sampled value fault component is with satisfied:
Wherein, I '
set=0.1A is the current data that line current instrument transformer secondary side measures gained sampled value; T '=5ms is the time of integration of sampled value current differential; M is that sampled data corresponding within the time of integration is counted; K
1for being greater than the integer of 1, for screening the safety factor of the state of emergency; The start unit that formula (1) is protected can be become, namely can start sampled value fault component integration/the accumulative and formula longitudinal impedance of specified time:
In formula,
for the voltage difference of the sampled value fault component that circuit two ends compensate through residual voltage; u
0m(t), u
0nt sampled value residual voltage that () is circuit both sides; r
m, r
0for mutual resistance, the zero sequence resistance of unit length circuit; F (rD) is circuit series impedance and relevant calculated value thereof; The electric state relation of sampled value is shown in Fig. 1.
The algorithm of formula (1) longitudinal impedance is mainly applicable to the transmission line demand that relaying protection is screened in state of emergency situation, mainly for the short trouble of protection exit place big current.In impedance computation, have employed integration/mode that is accumulative and formula equally can directly the result starting current differential integration used be quoted and reduce amount of calculation, also can strengthen the stablizing effect of impedance computation simultaneously, this shows, this algorithm becomes one of important evidence of innovation achievement of the present invention.
(2), when the electric current of circuit both sides power frequency fault component is with the measured value that satisfied stable acquisition is basic, conventional power frequency fault component longitudinal impedance can be started thus.Conventional power frequency fault component longitudinal impedance mainly adapts to the transmission line demand that relaying protection is screened when general state, and its performance has obtained valid certificates and delivered relevant paper
[1].
When the electric current of circuit both sides power frequency fault component is with satisfied:
Wherein, I
set=0.1A is line current instrument transformer secondary side gained power current data, can become the start unit that formula (2) is protected, and namely can start conventional power frequency fault component longitudinal impedance:
In formula,
for the voltage difference of the power frequency fault component that circuit two ends compensate through residual voltage;
for the residual voltage of circuit both sides; z
m, z
0for mutual impedance, the zero sequence impedance of unit length circuit; The electric state relation of power frequency fault component is shown in Fig. 2.
The sensitivity that the algorithm of formula (1) longitudinal impedance is screened in state is obviously better than formula (2) and current differential protection; and responsiveness is not slower than phasor current differential protection, the transmission line demand that relaying protection is screened in general state situation can be adapted to completely.
(3), when the specified time of circuit both sides or the power frequency fault component current differential integrating meter formula of inverse time lag meet relevant startup threshold, power frequency fault component integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag can be started equally.The power frequency fault component integration/sharpest edges that are accumulative and formula longitudinal impedance of specified time or inverse time lag are to adapt to the transmission line demand that relaying protection state is screened under microvariations state; it is the present invention's recent work after tight theory analysis and real simulating, verifying; it also becomes the important evidence of the present invention's innovation, and it is specially adapted to the less ruuning situation of generation of electricity by new energy output capacity.
(4) protect in support; the present invention's suggestion needs use one specified time or the power frequency full dose current differential integrating meter formula of inverse time lag; when it reaches startup threshold; power frequency full dose integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag can be started, also therefore become the Main Basis of the present invention's innovation.It is used after not only can being started by starting component, is more suitable for and does not need to start and continuous monitoring circuit real time execution situation, therefore do not limit by any condition and ruuning situation.
Due to longitudinal impedance by three complete different conditions, form of calculation different, mutually can not substitute and form with the electric parameters changed.The effect of similar stable triangular can be obtained from the form of calculation of impedance: though these three electric parameters any one occur for some reason engineering define the numerical bias of maximum magnitude, and therefore can not change their numerical value relativities each other, determine reliability and the sensitivity of longitudinal impedance thus.When the narrow numerical bias of appearance two electric parameters, also can guarantee that they possess the examination nargin of enough numerical bias each other, establish adaptability and the stability of longitudinal impedance thus.
Due to longitudinal impedance in computation structure there is unique stable triangular characteristic, therefore achieve it and can show the examination feature of multinomial brilliance and relevant performance characteristic in actual applications.Wherein have:
1. can resist because of current transformer progress of disease error and saturated the brought various adverse influence of electromagnetism, thus ensure that purchase and build the absolute reliability of modular protection;
2. current transformer occur obvious electric magnetically saturated while, longitudinal impedance can also keep larger examination nargin, and resist may with occurring the impact that voltage transformer progress of disease deviation causes simultaneously;
3. circuit both end voltage difference defines the associate feature of certain state complementation on physical model and mathematical expression, can overcome distance protection run into the technical barrier of voltage dead band;
4. longitudinal impedance possesses wider adaptive capacity; when system short circuit capacity is greater than the intrinsic natural through-put power of protected transmission line; adjust according to the actual operation parameters of existing highest voltage level, longest distance transmission line of alternation current; longitudinal impedance can without any parallel capacitive compensation, the various operation problems that process runs into above screening.
Although the cell protection algorithm that formula (2) proposes and above-mentioned properties feature have obtained valid certificates and have delivered relevant paper
[1]; But core of the present invention is the novelty algorithm proposing formula (1), formula (3) and formula (4) integration/accumulative and formula longitudinal impedance from novelty the basic protection form and functional characteristics thereof of formula (2) longitudinal impedance.The maximum feature of this new algorithm be due to introduced integration/accumulative and form of calculation, ensure that the data such as voltage item and electric current item possess the amplitude effectively can measured under any running environment, thus, the stability of longitudinal impedance result of calculation accesses sufficient guarantee, and longitudinal impedance that Here it is possesses the out of order key technology of reliable under various complex environment, sensitive examination, be also propose major technique foundation of the present invention.The technology needs of the transmission operation control mode that this feature is changeable under being adapted to generation of electricity by new energy environment especially and relaying protection in the present context thereof, meanwhile, this partial content also becomes the indispensable important component part of this integrated protection collocation method.
As long as the specified time of circuit both sides or the power frequency fault component current differential integrating meter formula of inverse time lag meet:
(wherein I '
setfor the minimum setting value of power frequency fault component current differential integral and calculating; T=20ms is the power frequency component cycle; the start unit that formula (3) is protected can be become equally), namely can start power frequency fault component integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag:
In formula, n be greater than 1 integer; T=20ms is the power frequency component cycle.
The sensitivity that the algorithm of formula (2) longitudinal impedance is screened in state will obviously be better than formula (2).Its sharpest edges are to adapt to the transmission line demand that relaying protection state is screened under microvariations state; When system operation mode is significantly less than conventional minimum operational mode, the capacity of short circuit that can be reflected as system is significantly less than routine, can fault current be reduced and therefore have influence on the stably measured of power frequency fault current component, find by analyzing, generation of electricity by new energy effectively can not control generate output as conventional electric power generation.Wherein maximum operational mode depends primarily on the total installation of generating capacity of wind field, and minimum operational mode then cannot effectively be predicted, and this situation be new-energy grid-connected join the technical problem that relaying protection constantly faces.Formula (2) algorithm is an innovatory algorithm of formula (1), the stability that the present invention improves impedance computation after tight theory analysis and real simulating, verifying, less (generation of electricity by new energy) running environment can be adapted to, also therefore achieve one of the present invention's Main Basis expanding utilization.Its maximum feature is denominator term because increasing impedance computation thus improves the stability of impedance computation, is specially adapted to the ruuning situation that generation of electricity by new energy output capacity is less.In order to form good cooperation with the power frequency fault component longitudinal impedance of routine on the protection act time limit, the shortest time interval suggestion of integration should not be less than a power frequency period, generally as required can the several power frequency period of proper extension.
Under the operational mode that certain is special (such as during reclosing), fault component can not guarantee stable acquisition,
The present invention's suggestion needs increase by specified time or the power frequency full dose current differential integrating meter formula of inverse time lag:
Wherein, I "
setfor the minimum setting value of power frequency full dose current differential integral and calculating, the start unit that formula (4) is protected can be become equally, namely can start power frequency full dose integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag.This kind of impedance algorithms can be started by start unit, also can not need to start, automatically the running status of continuous long-term Real-Time Monitoring circuit:
In formula, K
loadthe weighting Reliability factor that ≈ 2 ~ 3 affects for load component, n ' is for being not less than the integer of n; The electric state relation of power frequency full dose is shown in Fig. 3; The electric state relation of load is shown in Fig. 4.
With the impact of load component on the formula that the sharpest edges of formula (4) longitudinal impedance algorithm are its impedance computation, improve the reliability of impedance computation, the demand of transmission line relaying protection stable detection under mild state can be adapted to.When adopting the longitudinal impedance of power frequency full dose due to the joint effect of the factor such as load component and fault resstance, action resistance value of adjusting must do corresponding raising.The integral algorithm of formula (4) eliminates from principle the various adverse effects that generation of electricity by new energy brings, the impact etc. of less brought load component instability is exported comprising wind energy, merge These characteristics, finally become one of main feature of the present invention's innovation.In order to form good cooperation with the power frequency fault component integration of specified time or inverse time lag/accumulative and formula longitudinal impedance on the protection act time limit; the shortest time interval of integration needs the power frequency period definitely exceeding formula (3), generally can consider suitably to extend several power frequency period again.
The modular relaying protection system of the complete electric power system ultrahigh-voltage alternating-current transmission line based on new energy grid-connected power environment of Algorithm constitution of above-mentioned four kinds of longitudinal impedances.This protection can not only adapt to all running environment of new energy grid-connected power, forms the protection component combination of round-the-clock form, can improve the line protection level of conventional electric power generation environment equally.
That is, the algorithm of above-mentioned four kinds of longitudinal impedances: sampled value fault component integration/longitudinal impedance that is accumulative and formula can isolate the serious short trouble that the state of emergency reflects fast, the longitudinal impedance of conventional power frequency fault component can isolate short trouble corresponding to general state, play the effect of quick main protection, and the longitudinal impedance of power frequency fault component integration type can isolate microvariations state the minor failure that is suitable for, become the II segmentation unit relaying protection in band time limit, using the backup protection of the longitudinal impedance of power frequency full dose as above-mentioned protection, form the modular relaying protection system of the complete electric power system ultrahigh-voltage alternating-current transmission line based on new energy grid-connected power environment thus.This protection can not only adapt to all running environment of new energy grid-connected power, forms the protection component of round-the-clock form, can improve the line protection level of conventional electric power generation environment equally.
During concrete enforcement, when the transmission line of actual motion causes state accident for some reason, reflect often by the change of measuring gained electric parameters, finally can the status flag of qualitative analysis circuit according to the degree of line related electric parameters change, these status flags can Preliminary division be the state of emergency, general state, microvariations state and mild state.Can know according to fault component network, when a failure occurs, the fault component voltage of fault point is maximum, and along with observation station is away from fault point, the amplitude of fault component voltage will gradually reduce, until system point midway is reduced to zero; The system midpoint diffluence laterally from fault point of fault component electric current.According to the voltage and current signal of circuit gained form intrinsic state characteristic, with reference to the electric distributed constant feature of transmission line, the target signature and computing function of distinguishing its state can be known.Along with the research deepened continuously to longitudinal impedance, more can guarantee that it is screened characteristic and is better played, establish effect thus and the scope of application is expanded greatly.Integrated configuration new departure that the present invention utilizes the examination characteristic of longitudinal impedance to construct the supertension line based on generation of electricity by new energy to protect.Concrete enforcement to comprise the electric current of transmission line and voltage signal through fiber-optic communications traffic to circuit opposite end, and the resistance utilizing longitudinal impedance algorithm gained to calculate, obtains the examination result to circuit running status, establishes the identical criterion of protection act.
Technical scheme of the present invention, is responsible for Dunhuang ~ Jiuquan ~ Jinchang ~ Yongdeng 750kV ehv power transmission system that wind-powered electricity generation sends outside for target with the Northwest and carries out the research of modular relaying protection integrated configuration.The protection device of discriminating element of the present invention is housed see Fig. 1, m, n both sides, and input variable is transmission line voltage and current fault component, and voltage, electric current are obtained by line side voltage, current transformer, give simple signal in Fig. 1.Line voltage distribution, current signal through voltage, current transformer obtain after through low-pass filtering, sampling keep and A/D conversion after, deliver to microcomputer main system, and can directly according to sampled value fault component electric current and result determine whether the longitudinal impedance starting sampled value fault component integration type; Simultaneously, power frequency component is calculated by the algorithm of discrete/fast Flourier filtering, on this basis, respectively according to power frequency fault component electric current and result determine whether to start conventional power frequency fault component longitudinal impedance, determine whether start the longitudinal impedance of power frequency fault component integration type and determine whether to start the longitudinal impedance of power frequency full dose integration type according to the result of power frequency full dose current differential integrating meter formula according to the result of power frequency fault component current differential integrating meter formula.Then judge belonging to this impedance, whether each phase there occurs internal fault according to the resistance of above-mentioned each longitudinal impedance.In like manner, for there occurs (the most serious) electric magnetically saturated circuit on one-terminal current instrument transformer, longitudinal impedance also accurately can judge the actual motion state of circuit according to aforementioned principle.There occurs the significantly magnetically saturated circuit that simultaneously also there is voltage transformer progress of disease error of electricity for one end current transformer, longitudinal impedance still has screens nargin fully, ensures the accuracy differentiated according to this.
And for example, technical scheme of the present invention, is the method for the electric power system ultrahigh-voltage alternating-current relay protection of transmission line based on new energy grid-connected power running environment, specifically implements according to following steps:
Step 1: after record ripple, filtering process are carried out to the transmission line malfunction phase voltage broken down and electric current, recycle the different virtual conditions at current differential ANALYSIS OF CALCULATING circuit.When the current differential result of routine calculation gained is larger, the state of corresponding circuit is more serious, only has the time of delay shortening protection act, guarantees accurately to identify fault, and the infringement that minimizing fault is brought.
Step 2: compare longitudinal impedance
size with circuit series impedance and function f (rD) thereof, constructs rational criterion.
When after grid collapses, on the two ends current transformer of protected circuit, total energy measures the numerical value obtaining voltage and current failure component, and can guarantee the startup threshold that can be greater than relevant protection.After correspondence protection is triggered, its result of the longitudinal impedance corresponding to external area error must be greater than circuit series impedance and correlation function thereof; Troubles inside the sample space acquired results is just in time contrary, and two kinds of fault acquired results can be guaranteed to make a clear distinction between good and evil.Following criterion can be built thus:
After the protection of setting is activated; when above-mentioned criterion meets operation condition; reliably can be judged to internal fault; the moment no longer meeting operation condition when above-mentioned criterion is exactly external area error or system disturbance, and the determination of system running state effectively can improve the speed of protection act: the state of emergency, general state, microvariations state and mild state.
With reference to Fig. 5, the failure removal sequential of transmission line, t
1moment is that transmission line breaks down, t
2moment is the setting time of sampled value fault component integration/accumulative and formula longitudinal impedance, t
3moment is the setting time of conventional power frequency fault component longitudinal impedance, t
4moment is the setting time of power frequency fault component integration/accumulative and formula longitudinal impedance, t
5moment is the setting time of power frequency full dose integration/accumulative and formula longitudinal impedance.When transmission line malfunction, (the generation moment is t=t
1) after generation, i.e. t
1< t < t
2time; now the equivalent action threshold value that obtains of converting the highest; the examination of the lower fault that is in a state of emergency mainly for transmission line; as sampled value fault component longitudinal impedance; signal transacting bring the relevant action delay time to be defined as 5mS; after having judged and determine to protect whether action, terminate relevant calculating.Work as t
2< t < t
3time; now determine that the foundation of action threshold value depends primarily on the minimum electric parameters requirement guaranteed required for conventional longitudinal impedance stability Calculation; also be the reference object of other method contrast; the examination of fault under general state is in mainly for transmission line; the same, as conventional power frequency fault component longitudinal impedance, the action delay time generally can reach about 20mS; after having judged and determine to protect whether action, situation is the same.Work as t
3< t < t
4time, now the equivalent action threshold value that obtains of converting will be starkly lower than conventional longitudinal impedance, the examination of fault under microvariations state is in mainly for transmission line, particularly when run into generation of electricity by new energy be in low capacity export environment under (its operational mode is significantly less than normal minimum operational mode), as specified time integration/accumulative and formula power frequency fault component longitudinal impedance, signal transacting bring the relevant action delay time to be defined as several times and power frequency period.Work as t
4< t < t
5time, now the equivalent action threshold value obtained that converts will be minimum, be in the examination of fault under mild state mainly for transmission line, as specified time integration/accumulative and formula power frequency full dose longitudinal impedance, signal transacting bring the relevant action delay time the longest.In addition, 1. curve is the operating characteristics of inverse time lag power frequency fault component integration/accumulative and formula longitudinal impedance; 2. curve is the operating characteristics of inverse time lag power frequency fault component integration/accumulative and formula longitudinal impedance.The qualitative analysis according to above-mentioned operating characteristics can be known; under system cloud gray model is in any one mode; all at least ensure more than one specific protected modes can adapt to; and guarantee the impact overcoming system disturbance to greatest extent in actual applications; guarantee reliability and the sensitivity of protection, form the integrated configuration new departure a kind of modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected thus.
Technical scheme of the present invention, in the actual motion of extra high voltage network, the electrical characteristic intrinsic according to the fault component network of fault generation, numerical value conversion and the physical link feature of analytical model essence, a kind of transmission line malfunction character discriminating method based on longitudinal impedance characteristic is proposed, the examination boundary of longitudinal impedance is only relevant with transmission line series impedance, in this approach by the impact of the outer other factors of state, this method and the existing traditional criterion of the basic electric characteristic of transmission line that utilizes are got along amiably and peacefully simultaneously, complementary use, effectively can improve reliability and the sensitivity of protection.Be expected to the effective means as the modular nature of trouble identification of superhigh pressure long distance transmission line Novel intelligent based on new energy grid-connected power.Technical scheme of the present invention also can as the relay protection of transmission line of existing conventional electric power generation effectively supplementing based on fault phase-splitting electric parameters characteristic criterion.On the basis that high-performance computer protection, wide frequency domain digital communication and intelligent electronic mutual inductance treatment technology are increasingly mature, technical scheme of the present invention has a good application prospect.
In order to set forth Main Feature of the present invention further, present the three-phase line model of power frequency fault component in FIG.In Fig. 1, m and n is circuit two ends electrical measurement points;
with
it not the power frequency fault component obtaining each phase voltage of circuit and electric current from two ends measurement point in real time;
fault point equivalent voltage and fault current respectively; R
fit is fault point fault resstance; D and d is protected circuit total length and from measurement point m to the line length of fault point respectively; z
s, z
1, z
mthe self-impedance of unit length circuit, positive sequence impedance and mutual impedance respectively; Z
sm(L
sm), Z
mm(L
mm), Z
1m(L
1m), Z
sn(L
sn), Z
mn(L
mn) and Z
1n(L
1n) be the self-impedance (inductance) of circuit two side system, positive sequence impedance (inductance) and mutual impedance (inductance) respectively.
Last it is noted that the foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, although with reference to previous embodiment to invention has been detailed description, for a person skilled in the art, it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (7)
1., based on a transmission line of alternation current cell protection integrated configuration method for new forms of energy, it is characterized in that, mainly comprise:
A, the current data utilizing each phase acquisition in circuit both sides to arrive, qualitatively judge the running status of circuit immediately;
B, carry out qualitatively judging made conclusion according to step a, start multi-form longitudinal impedance respectively; When transmission line impels the increment of above-mentioned phase induced current effectively to measure for some reason, namely can start corresponding longitudinal impedance algorithm and whether occur internal fault according to the result determination circuit of longitudinal impedance.
2. the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line according to claim 1, is characterized in that, described step a, specifically comprises:
Utilize the sampled value fault component electric current of each phase in circuit both sides
power frequency fault component electric current
and power frequency full dose electric current
immediately the qualitative judgement to circuit running status is obtained according to the size of each phase measured current calculating amplitude;
Wherein,
m, n are circuit two ends electric measurement point.
3. the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected according to claim 1 and 2, it is characterized in that, described step b, specifically comprises:
B1, when the electric current of circuit both sides sampled value fault component with when meeting the startup threshold of the state of emergency, sampled value fault component integration/the accumulative and formula longitudinal impedance of specified time can be started thus; The integration of sampled value fault component/accumulative and formula longitudinal impedance are mainly used in the short trouble screening protection exit place big current;
B2, when circuit both sides power frequency fault component electric current and meet stable obtain basic measured value time, conventional power frequency fault component longitudinal impedance can be started thus;
B3, when the specified time of circuit both sides or the power frequency fault component current differential integrating meter formula of inverse time lag meet relevant start threshold time, power frequency fault component integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag can be started equally;
B4, to protect in support, need use one to definite time-lag or the power frequency full dose current differential integrating meter formula of inverse time lag, when it reach start threshold time, power frequency full dose integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag can be started.
4. the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected according to claim 3, it is characterized in that, described step b1, specifically comprises:
When the electric current of circuit both sides sampled value fault component is with satisfied:
Wherein, I '
set=0.1A is the current data that line current instrument transformer secondary side measures gained sampled value; T '=5ms is the time of integration of sampled value current differential; M is that sampled data corresponding within the time of integration is counted; K
1for being greater than the integer of 1, for screening the safety factor of the state of emergency; The start unit that formula (1) is protected can be become, namely can start sampled value fault component integration/the accumulative and formula longitudinal impedance of specified time
In formula,
for the voltage difference of the sampled value fault component that circuit two ends compensate through residual voltage;
the each phase voltage of sampled value for circuit both sides;
the each phase current of sampled value for circuit both sides; u
0m(t), u
0nt sampled value residual voltage that () is circuit both sides; r
m, r
0for mutual resistance, the zero sequence resistance of unit length circuit; F (rD) is circuit series impedance and relevant calculated value thereof; RD is total track length series resistance.
5. the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected according to claim 4, it is characterized in that, described step b2, specifically comprises:
When the electric current of circuit both sides power frequency fault component is with satisfied:
Wherein, I
set=0.1A is line current instrument transformer secondary side gained power current data, can become the start unit that formula (2) is protected, and namely can start conventional power frequency fault component longitudinal impedance:
In formula,
for the voltage difference of the power frequency fault component that circuit two ends compensate through residual voltage;
for each phase power-frequency voltage fault component of circuit both sides;
for each phase power current fault component of circuit both sides;
for the residual voltage of circuit both sides; z
m, z
0for mutual impedance, the zero sequence impedance of unit length circuit; ZD is total track length series impedance.
6. the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected according to claim 5, it is characterized in that, described step b4, specifically comprises:
As long as the specified time of circuit both sides or the power frequency fault component current differential integrating meter formula of inverse time lag meet:
Wherein, I '
setfor the minimum setting value of power frequency fault component current differential integral and calculating; T=20ms is the power frequency component cycle; the start unit that formula (3) is protected can be become equally, namely can start power frequency fault component integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag:
In formula, n be greater than 1 integer; T=20ms is the power frequency component cycle.
7. the integrated configuration method of the modular protection of ultrahigh-voltage alternating-current transmission line based on new-energy grid-connected according to claim 6, it is characterized in that, described step b4, specifically also comprises:
Increase a specified time or the power frequency full dose current differential integrating meter formula of inverse time lag:
Wherein, I "
setfor the minimum setting value of power frequency full dose current differential integral and calculating, the start unit that formula (4) is protected can be become equally, namely can start power frequency full dose integration/the accumulative and formula longitudinal impedance of specified time or inverse time lag;
This kind of impedance algorithms can be started by start unit, also can not need to start, automatically the running status of continuous long-term Real-Time Monitoring circuit:
In formula,
for the voltage difference of the power frequency full dose that circuit two ends compensate through residual voltage;
for each phase power-frequency voltage full dose of circuit both sides;
for each phase power current full dose of circuit both sides; K
loadthe weighting Reliability factor that ≈ 2 ~ 3 affects for load component, n ' is for being not less than the integer of n.
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