CN112260242A - Pilot protection method for DFIG-containing power distribution network line - Google Patents

Pilot protection method for DFIG-containing power distribution network line Download PDF

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CN112260242A
CN112260242A CN202010989547.4A CN202010989547A CN112260242A CN 112260242 A CN112260242 A CN 112260242A CN 202010989547 A CN202010989547 A CN 202010989547A CN 112260242 A CN112260242 A CN 112260242A
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breaker
distance
distribution network
dfig
current
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CN112260242B (en
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段建东
杨威
陈童
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Xian University of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy

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  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a pilot protection method for a DFIG-containing power distribution network line, which is implemented specifically according to the following steps of 1, obtaining a waveform of a breaker a and a current reverse waveform of the breaker b through a programmable processor a and a programmable processor b; step 2, calculating the mismatching degree of the currents at the two ends, if the calculated M value is greater than the setting value, performing step 3, and if the calculated M value is less than the setting value, continuing to sample; step 3, respectively calculating the one-way distances between two ends of the AB section line, comparing the two data, and if the two one-way distances are not equal, performing the step 2 again; if the two unidirectional intervals are equal, the circuit breaker a and the circuit breaker b trip to break the circuit; the method solves the problem that the protection method for the distribution network connected with the DFIG in the prior art cannot adapt to the low voltage ride through and the double-end power supply network of the DFIG.

Description

Pilot protection method for DFIG-containing power distribution network line
Technical Field
The invention belongs to the technical field of distribution network relays and relates to a pilot protection method for a DFIG-containing distribution network line.
Background
The problems of environmental pollution, climate change, energy safety, sustainable development and the like are increasingly highlighted, most countries around the world already put new energy into the national energy priority development strategy, and new energy power generation meets the development opportunity. The generation of electricity by using new energy has become a main form of electricity generation, and new energy is injected into the electricity. But new energy generation also presents challenges.
After the distributed energy is connected to the power distribution network, some adverse effects are brought to the power quality, the power flow, the protection, the reclosing and the like of the power distribution network. After the traditional power distribution network is connected to distributed energy sources which are random, uncertain and large in fluctuation, the single-ended power distribution network is changed into a novel multi-end multi-source power distribution network, and the trend is changed from the single direction of the transformer substation flow direction load into multi-direction flow. Three-section current protection of the traditional power distribution network based on a radiation type structure, unidirectional short-circuit current and time phase delay setting is not suitable for a new power distribution network form any more, and the problems are numerous.
The existing protection method for the power distribution network after the doubly-fed induction wind driven generator is connected into the power distribution network mainly comprises the following steps: (1) the advantages of inverse time-lag overcurrent and differential protection are analyzed, the inverse time-lag overcurrent and differential protection are complementary and take the undeterminable branch of the power distribution network into account, inverse time-lag current differential protection of the active power distribution network is provided, and the communication requirement is reduced; (2) a protection scheme based on communication is provided, multipoint information can be fully utilized to configure and set protection according to real time through a communication mode, and once communication fails or information is wrong, protection is invalid. (3) Considering the actual configuration of a power distribution network, under the conditions of low sampling rate and weak communication synchronization, analyzing the fault, and then analyzing the difference of short-circuit current amplitudes at two sides of a distributed wind power system tie line to construct a novel differential protection with a braking characteristic; (4) the influence of the new energy capacity on differential protection is analyzed, the network access capacity is limited to be matched with the protection, however, the method for limiting the distributed wind power access capacity is contrary to the national development concept, and the method cannot be widely popularized; (5) the impedance measured at the side protection installation position of the wind power plant is considered to be equivalent impedance of the wind power plant at the back side and is influenced by various fault conditions, such as power generation capacity, wind speed, frequency and the like of the wind power plant, and the equivalent positive and negative sequence impedance of the wind power plant is considered to be equal through analysis, so that self-adaptive distance protection along with different fault conditions is provided, however, the equivalent positive and negative sequence impedance of the DFIG is not equal, the amplitude and phase angle of the positive sequence impedance fluctuate obviously, and therefore the reliability of the protection scheme is insufficient. In summary, the protection method for the distribution network connected with the DFIG in the prior art cannot be well adapted to the technical problem of deviation of short-circuit current on frequency spectrum and phase caused by the low voltage ride through requirement of the DFIG, and the problem of protection caused by changing the distribution network from a single-ended power supply to a double-ended power supply also needs to be solved.
Disclosure of Invention
The invention aims to provide a pilot protection method for a line of a distribution network with a DFIG (doubly-fed induction generator), which solves the problem that the protection method for the distribution network connected with the DFIG in the prior art cannot adapt to low voltage ride through and a double-end power supply network of the DFIG.
The technical scheme adopted by the invention is that,
a pilot protection method for a DFIG-containing power distribution network line is implemented according to the following steps:
step 1, current values of a breaker a and a breaker b on an AB line are respectively acquired through a transformer a and a transformer b, the transformer a inputs the measured current values into a programmable processor a, the transformer b inputs the measured current values into a programmable processor b, and the programmable processor a and the programmable processor b respectively invert the current of the breaker a or a tail-end breaker b to obtain a waveform of the breaker a and a reverse waveform of the current of the breaker b;
step 2, calculating the mismatching degree of currents at two ends by utilizing the waveform of the breaker a and the reverse waveform of the current of the breaker b obtained in the step 1, if the calculated M value is greater than the setting value, performing the step 3, and if the calculated M value is less than the setting value, continuing sampling;
step 3, respectively calculating unidirectional intervals H (A, B) and H (B, A) at two ends of the AB section line, comparing the two data, if the two unidirectional intervals are not equal, assigning the maximum value of the current minimum point distance as 0, and repeating the step 2; and if the two unidirectional intervals are equal, the circuit breaker a and the circuit breaker b trip to break the circuit, and the pilot protection of the active power distribution network circuit is completed.
The invention is also characterized in that:
step 1 is specifically carried out as follows: the method comprises the steps of simulating different types of faults of the power distribution network through a PSCAD simulation experiment, importing fault current data obtained through a sliding data window into a matlab program, and obtaining a waveform of a breaker a and a current reverse waveform of the breaker b under different faults by inverting the current of the breaker b.
The step 2 is specifically implemented by: solving Hausdorff distance of the circuit breaker a waveform and the circuit breaker b current reverse waveform under different faults obtained in the step 1, continuing sampling if the obtained Hausdorff distance is smaller than a setting value, and performing a step 3 if the obtained Hausdorff distance is larger than the setting value, wherein the Hausdorff distance calculation method comprises the following steps:
suppose that there are two sets of discrete point data of current as A ═ a1，...，aq}，B＝{b1，...，bq}。
Then the H distance between the two sets of points is defined as:
Figure BDA0002690396800000031
specifically, for a certain point a in the point set AiThere must be a distance a in the point set BiNearest point bjThen aiAnd bjThe distance between them is called aiMinimum dot spacing of → B; namely:
||ai-bj||≤||ai-bk1 is equal to or less than k and is equal to q and j 2
Figure BDA0002690396800000032
Meanwhile, all points in the point set A have at least one minimum point distance with respect to the point set B, and the maximum value of the minimum point distances is the one-way distance of A → B, namely:
Figure BDA0002690396800000041
similarly, for a certain point B in the point set BiThere must be a point a closest to bi in the point set AjThen biAnd ajIs called biMaximum of → ASmall dot pitch, i.e.:
||ai-bj||≤||ai-bk1 is equal to or less than k and is equal to or less than q, and k is not equal to j 5
Figure BDA0002690396800000042
Therefore, all points in the point set B also have at least one minimum point distance for the point set a, and the maximum value of these minimum point distances is the one-way distance of B → a:
Figure BDA0002690396800000043
the final Hausdorff distance is defined as the maximum value of two one-way distances h (A, B) and h (B, A);
H(A，B)＝max(h(A,B),h(B,A)) 8
for curves A and B formed by two groups of discrete data, a minimum point distance exists between each point and the other curve; the maximum H (B, a) of the two single-phase distances is defined as the final Hausdorff distance H (a, B), i.e. the degree of mismatch of the currents at both ends is calculated for the breaker a and breaker B current-reversal waveforms.
The setting value in step 2 is 0.
And (3) calculating unidirectional intervals H (A, B) and H (B, A) at two ends of the AB section line, and specifically implementing the following steps:
order:
Figure BDA0002690396800000044
Figure BDA0002690396800000051
in combination with the above formula, delta if the line has an in-zone fault1＝△2If there is anomalous data, because h (A, B)≠h(B,A)，△1And Δ2Will not equal 1; using this difference, the cause of the increase in Hausdorff distance can be identified, due to the slight error in the sampled values and in the simulation, the Δ that will be caused by the fault1And Δ2Is in the range of 0.8 to 1.2.
The invention has the beneficial effects that: the invention relates to a pilot protection method for a line of a distribution network containing a DFIG (doubly fed induction generator), which solves the problem that the protection method for the distribution network connected with the DFIG in the prior art cannot adapt to low voltage ride through of the DFIG; the pilot protection is utilized in a dual power supply mode, data sampling is carried out by adopting a sliding data window method, the protection rapidity is improved, the waveform mismatching degree of two ends of a protected line is calculated by adopting an improved Hausdorff algorithm, and therefore an intra-area fault or an extra-area fault is realized, and the protection reliability is improved.
Drawings
FIG. 1 is a circuit diagram adopted by a pilot protection method for a DFIG-containing power distribution network line of the invention;
FIG. 2 is a flow chart of a pilot protection method for a DFIG-containing power distribution network line according to the present invention;
FIG. 3 is a schematic diagram illustrating the calculation of the waveform mismatching degree by Hausdorff in the pilot protection method for the DFIG-containing power distribution network line according to the present invention;
fig. 4 is a current waveform obtained after sampling current at two ends of a line and performing reverse processing on a section of current according to the pilot protection method for a distribution network line including a DFIG;
FIG. 5 is a line graph of calculated results of waveform mismatching degrees of the pilot protection method for the distribution network line including the DFIG under different fault types according to the invention;
fig. 6 is a line graph of the calculation result of the waveform mismatching degree of the pilot protection method for the distribution network line including the DFIG under different fault positions.
In the figure, 1 is a power supply, 2 is a step-down transformer, 3 is a bus, 4 is a breaker a, 5 is an AB section circuit, 6 is a mutual inductor a, 7 is a programmable processor a, 8 is an action controller a, 9 is a breaker B, 10 is a mutual inductor B, 11 is a programmable processor B, 12 is an action controller B, 13 is a bus, 14 is a DFIG wind generating set, 15 is a transformer, 16 is a breaker C, 17 is a BC section circuit, 18 is a C bus, and 19 is a load.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention discloses a pilot protection method for a DFIG-containing power distribution network line, which takes the following circuit as an example for explanation: as shown in fig. 1, the power supply 1 includes a power supply 1, the power supply 1 is electrically connected with a step-down transformer 2 and an a bus 3 in sequence, the a bus 3 is electrically connected with an AB segment circuit 5, one end of the AB segment circuit 5 is electrically connected with the a bus 3, the other end of the AB segment circuit 5 is electrically connected with a B bus 13, the AB segment circuit 5 is electrically connected with a breaker a4, a transformer a6, a transformer B10 and a breaker B9 in sequence, a breaker a4 and a transformer a6 are located near the a bus 3, a transformer B10 and a breaker B9 are located near the B bus 13, a breaker a4 is electrically connected with an action controller a8, a transformer a6 is electrically connected with a programmable processor a7, a programmable processor a7 is electrically connected with the action controller a8, a transformer B10 is electrically connected with a programmable processor B11, a breaker B is electrically connected with the action controller B12, and a B12 is. The B bus 13 is sequentially electrically connected with a transformer 15 and a DFIG wind generating set 14, the B bus 13 is also electrically connected with a BC circuit section 17, the BC circuit section 17 is positioned on one side of the B bus 13 far away from the AB circuit section 5, one end of the BC circuit section 17 is electrically connected with the B bus 13, the other end of the AB circuit section 5 is electrically connected with a C bus 18, the BC circuit section 17 is electrically connected with a circuit breaker C16, the circuit breaker C16 is positioned near the B bus 13, and the C bus 18 is connected with a load 19.
The invention discloses a pilot protection method for a DFIG-containing power distribution network line, which is implemented according to the following steps as shown in figure 2:
step 1, current values of a breaker a (4) and a breaker b (9) on an AB line 5 are respectively collected through a transformer a (6) and a transformer b (10), the transformer a (6) inputs the measured current values into a programmable processor a (7), the transformer b (10) inputs the measured current values into a programmable processor b (11), and the programmable processor a (7) and the programmable processor b (11) respectively invert the current of the breaker a4 or a terminal breaker b9 to obtain a breaker a4 waveform and a breaker b9 current reverse waveform;
step 1 is specifically carried out as follows: the method comprises the steps of simulating different types of faults of the power distribution network through a PSCAD simulation experiment, importing fault current data obtained through a sliding data window into a matlab program, and obtaining a breaker a4 waveform and a breaker b9 current reverse waveform under different faults by inverting the current of a breaker b 9. Step 2, calculating the mismatching degree of currents at two ends by using the waveform of the circuit breaker a4 and the reverse waveform of the current of the circuit breaker b9 obtained in the step 1, performing the step 3 if the calculated M value is greater than a setting value, and continuing sampling if the calculated M value is less than the setting value;
the step 2 is specifically implemented by: solving the Hausdorff distance of the circuit breaker a4 waveform and the circuit breaker b9 current reverse waveform under different faults obtained in the step 1, if the obtained Hausdorff distance is smaller than a setting value, continuing sampling, and if the obtained Hausdorff distance is larger than the setting value, performing the step 3, wherein the Hausdorff distance calculation method comprises the following steps of:
suppose that there are two sets of discrete point data of current as A ═ a1，...，aq}，B＝{b1，...，bq}。
Then the H distance between the two sets of points is defined as:
Figure BDA0002690396800000071
specifically, for a certain point a in the point set AiThere must be a distance a in the point set BiNearest point bjThen aiAnd bjThe distance between them is called aiMinimum dot spacing of → B; namely:
||ai-bj||≤||ai-bk1 is equal to or less than k and is equal to q and j 2
Figure BDA0002690396800000072
Meanwhile, all points in the point set A have at least one minimum point distance with respect to the point set B, and the maximum value of the minimum point distances is the one-way distance of A → B, namely:
Figure BDA0002690396800000081
similarly, for a certain point B in the point set BiThere must be a point a closest to bi in the point set AjThen biAnd ajIs called biMinimum dot spacing of → a, i.e.:
||ai-bj||≤||ai-bk1 is equal to or less than k and is equal to or less than q, and k is not equal to j 5
Figure BDA0002690396800000082
Therefore, all points in the point set B also have at least one minimum point distance for the point set a, and the maximum value of these minimum point distances is the one-way distance of B → a:
Figure BDA0002690396800000083
the final Hausdorff distance is defined as the maximum value of two one-way distances h (A, B) and h (B, A);
H(A，B)＝max(h(A,B),h(B,A)) 8
as shown in fig. 3, in the calculation process of the Hausdorff algorithm, for curves a and B formed by two sets of discrete data, a minimum point distance exists between each point and the other curve; for example, the minimum dot pitch 1 → B of the dots 1 in a is a distance between (1,2), and the minimum dot pitch of all the dots in a is arranged, and the maximum dot pitch is the minimum dot pitch (9,8) of the dots 9 → B, so the single-phase distance h (a, B) of a → B is a distance between (9, 8). Similarly, the single-phase distance h (B, A) of A → B is the distance between (10, 9). The maximum H (B, A) of the two single-phase distances is defined as the final Hausdorff distance H (A, B), and the degree of mismatch of the currents at the two ends is calculated for the breaker a4 waveform and the breaker B9 current reversal waveform.
The setting value in step 2 is 0.
The setting value dereferencing principle is as follows:
after the inversion processing, when the circuit operates in a steady state, the current waveforms at the two ends of the AB line are completely matched with an ideal state, and when a fault occurs, i2Increase in the positive direction, -i1The degree of mismatch becomes immediately apparent as the inverse increases. As shown in fig. 4, if a fault occurs outside the AB line region, the capacitance influence is small considering that the distribution line is generally short, so that the current flowing across the line is theoretically consistent with that in steady state operation, i.e., perfectly matched, as viewed from the degree of matching.
Based on this feature, it can be derived: in normal operation/out-of-range fault, -i1And i2Substantially completely overlapping, with a degree of mismatch M substantially equal to 0, i after a fault in the zone2And-i1The horse stands with a large difference, and the degree of mismatch M between them is a number significantly larger than 0. Using this difference, it is possible to identify whether the failure occurs inside or outside the zone.
In summary, a pilot protection criterion of the line between the DFIG and the large system can be constructed:
m ≈ 0 normal operation or out-of-range fault
M > >0 in-zone failure
Step 3, respectively calculating unidirectional distances H (A, B) and H (B, A) at two ends of the AB section line 5, comparing the two data, if the two unidirectional distances are not equal, assigning the maximum value of the current minimum point distance as 0, and repeating the step 2; if the two one-way distances are equal, the circuit breaker a4 and the circuit breaker b9 trip to break the circuit, and the pilot protection of the DFIG-containing power distribution network circuit by utilizing the waveform mismatching degree is completed.
Since H (a, B) ≠ H (B, a) when abnormal data occurs, and the waveform is approximately symmetrical when the line is short-circuited and after one-end current inversion processing is performed, that is, H (a, B) ═ H (B, a), in consideration of this characteristic, the unidirectional pitches H (a, B) and H (B, a) at both ends of the AB segment line 5 are calculated in step 3, specifically according to the following implementation:
order:
Figure BDA0002690396800000091
Figure BDA0002690396800000092
in combination with the above formula, delta if the line has an in-zone fault1＝2If there is abnormal data, the delta is 1 because h (A, B) ≠ h (B, A)1And Δ2Will not equal 1; using this difference, the cause of the increase in Hausdorff distance can be identified, due to the slight error in the sampled values and in the simulation, the Δ that will be caused by the fault1And Δ2Is in the range of 0.8 to 1.2.
Verifying different fault types and fault positions
The specific process is as follows:
(1) the occurrence of faults at different positions on the line also affects the magnitude of the short-circuit current and thus the calculation of the degree of mismatch. Therefore, multiple sets of simulation are carried out at different positions in the protected line, and the fault type is three-phase short circuit. The simulation results are shown in fig. 5. As can be seen from fig. 5, anywhere along the full length of the line, the protection action value is greater than 1 for a short time (4.8ms) after the fault occurs, i.e. the proposed protection scheme can act reliably and quickly. However, the test results show that the different positions where the fault occurs affect the protection operation value, and the closer the fault position is to the system side (about 0% of the entire line length), the lower the protection operation value is, and the reliability is not affected, but the sensitivity is reduced. Therefore, the subsequent simulation verification is carried out under the most extreme condition of the fault occurrence position, and the performance of the protection scheme is verified
(2) At a distance of 0%, i.e. the very head of the line, a three-phase short circuit, an AB two-phase ground short circuit and an AB interphase short circuit, respectively, and also a single-phase ground were set, and the performance of the proposed protection scheme was tested in extreme cases, with the results shown in fig. 6. As can be seen from fig. 6, in addition to the single-phase grounding, when another type of fault occurs at the head end of the line, the protection still can operate reliably and quickly, but when a single-phase short circuit occurs, the operation value of the protection is about 1.8, and at this time, although the sensitivity is reduced, the protection still can operate reliably.
The pilot protection method for the DFIG-containing power distribution network line utilizes pilot protection in a dual power supply mode, adopts the sliding data window for processing, is simple and quick in calculation process, utilizes the improved Hausdorff algorithm to calculate the mismatching degree of the two ends of the protected line, and is high in practicability in the power distribution network; the reliability of protection is improved, and fault identification and removal are facilitated.
The invention relates to a pilot protection method for a line of a distribution network containing a DFIG (doubly fed induction generator), which solves the problem that the protection method for the distribution network connected with the DFIG in the prior art cannot adapt to low voltage ride through of the DFIG; the pilot protection is utilized in a dual power supply mode, data sampling is carried out by adopting a sliding data window method, the protection rapidity is improved, the waveform mismatching degree of two ends of a protected line is calculated by adopting an improved Hausdorff algorithm, and therefore an intra-area fault or an extra-area fault is realized, and the protection reliability is improved.
The pilot protection method for the active power distribution network circuit utilizes pilot protection in a dual power supply mode, adopts the processing of a sliding data window, has simple and quick calculation process, and utilizes the improved Hausdorff algorithm to calculate the mismatching degree of time domain current waveforms at two ends of a protected circuit so as to judge whether the circuit has an in-zone fault or an out-zone fault, thereby improving the reliability of protection. The problem that a protection method for a power distribution network connected with a DFIG in the prior art cannot adapt to low-voltage ride through of the DFIG is solved. The practicability in the power distribution network is high; the reliability of protection is improved, and fault identification and removal are facilitated.

Claims (5)

1. A pilot protection method for a DFIG-containing power distribution network line is characterized by being implemented according to the following steps:
step 1, current values of a breaker a (4) and a breaker b (9) on an AB line (5) are respectively acquired through a transformer a (6) and a transformer b (10), the transformer a (6) inputs the measured current values into a programmable processor a (7), the transformer b (10) inputs the measured current values into a programmable processor b (11), and the programmable processor a (7) and the programmable processor b (11) respectively invert the current of the breaker a (4) or a terminal breaker b (9) to obtain a waveform of the breaker a (4) and a current inversion waveform of the breaker b (9);
step 2, calculating the mismatching degree of currents at two ends by using the waveform of the breaker a (4) and the reverse current waveform of the breaker b (9) obtained in the step 1, performing the step 3 if the calculated M value is greater than the setting value, and continuing sampling if the calculated M value is less than the setting value;
step 3, respectively calculating unidirectional intervals H (A, B) and H (B, A) at two ends of the AB section line (5), comparing the two data, if the two unidirectional intervals are not equal, assigning the maximum value of the current minimum point distance as 0, and repeating the step 2; if the two unidirectional intervals are equal, the circuit breaker a (4) and the circuit breaker b (9) trip to break a circuit, and the pilot protection of the DFIG-containing power distribution network circuit by utilizing the waveform mismatching degree is completed.
2. The method for pilot protection of the DFIG-containing power distribution network line according to claim 1, wherein the step 1 is specifically implemented as follows: the method comprises the steps of simulating different types of faults of the power distribution network through a PSCAD simulation experiment, importing fault current data obtained through a sliding data window into a matlab program, and obtaining the wave forms of a breaker a (4) and the current reverse wave forms of a breaker b (9) under different faults by inverting the current of the breaker b (9).
3. The method for pilot protection of the DFIG-containing power distribution network line according to claim 1, wherein the step 2 is specifically implemented by: solving the Hausdorff distance of the current reverse waveforms of the breaker a (4) and the breaker b (9) under different faults obtained in the step (1), continuing sampling if the obtained Hausdorff distance is smaller than a setting value, and performing the step (3) if the obtained Hausdorff distance is larger than the setting value, wherein the Hausdorff distance calculation method comprises the following steps:
suppose that there are two sets of discrete point data of current as A ═ a1，...，aq}，B＝{b1，...，bq}。
Then the H distance between the two sets of points is defined as:
Figure FDA0002690396790000021
specifically, for a certain point a in the point set AiThere must be a distance a in the point set BiNearest point bjThen aiAnd bjThe distance between them is called aiMinimum dot spacing of → B; namely:
||ai-bj||≤||ai-bk1 < k > q and q ≠ j (2)
Figure FDA0002690396790000022
Meanwhile, all points in the point set A have at least one minimum point distance with respect to the point set B, and the maximum value of the minimum point distances is the one-way distance of A → B, namely:
Figure FDA0002690396790000023
similarly, for a certain point B in the point set BiThere must be a point a closest to bi in the point set AjThen biAnd ajIs called biMinimum dot spacing of → a, i.e.:
||ai-bj||≤||ai-bk1 is less than or equal to k is less than or equal to q, and k is not equal to j (5)
Figure FDA0002690396790000024
Therefore, all points in the point set B also have at least one minimum point distance for the point set a, and the maximum value of these minimum point distances is the one-way distance of B → a:
Figure FDA0002690396790000025
the final Hausdorff distance is defined as the maximum value of two one-way distances h (A, B) and h (B, A);
H(A，B)＝max(h(A,B),h(B,A)) (8)
for curves A and B formed by two groups of discrete data, a minimum point distance exists between each point and the other curve; the maximum H (B, a) of the two single-phase distances is defined as the final Hausdorff distance H (a, B), and the degree of mismatch of the currents at the two ends is calculated for the breaker a (4) waveform and the breaker B (9) current reversal waveform.
4. The method for pilot protection of the DFIG-containing power distribution network line according to claim 1, wherein the setting value in the step 2 is 0.
5. The pilot protection method for the distribution network line including the DFIG according to claim 1, wherein the step 3 is implemented by calculating unidirectional distances H (a, B) and H (B, a) between two ends of the AB segment line (5) as follows:
order:
Figure FDA0002690396790000031
Figure FDA0002690396790000032
in combination with the above formula, delta if the line has an in-zone fault1＝2If there is abnormal data, the delta is 1 because h (A, B) ≠ h (B, A)1And Δ2Will not equal 1; using this difference, the cause of the increase in Hausdorff distance can be identified, due to the slight error in the sampled values and in the simulation, the Δ that will be caused by the fault1And Δ2Is in the range of 0.8 to 1.2.
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