CN108808634B - High-voltage direct-current transmission line pilot protection method based on smoothing reactor voltage - Google Patents
High-voltage direct-current transmission line pilot protection method based on smoothing reactor voltage Download PDFInfo
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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
- H02H7/268—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 dc systems
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- 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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
the invention relates to a pilot protection method for a high-voltage direct-current transmission line based on smoothing reactor voltage, which mainly utilizes the sudden change directions of the smoothing reactor voltage at the rectifying side and the smoothing reactor voltage at the inverting side of the high-voltage direct-current transmission line to realize the discrimination of faults inside and outside a region, and comprises the following steps: and acquiring the voltages at two ends of the smoothing reactor at the rectifying side and the smoothing reactor at the inverting side of the direct-current line through a voltage acquisition device. And respectively judging mutation directions pM and pN of the smoothing reactor voltage uM and the smoothing reactor voltage uN on the rectifying side and the inverting side. And identifying the faults inside and outside the region by using the sudden change directions pM and pN of the voltage of the smoothing reactor, and performing fault pole selection on the faults inside the region.
Description
Technical Field
The invention relates to the field of ultra/extra-high voltage direct current transmission relay protection of a power system, in particular to a pilot protection method of a high-voltage direct current transmission line based on voltage characteristics of a smoothing reactor.
background
With the increasing application of High Voltage Direct Current (HVDC) transmission in long-distance transmission, asynchronous grid interconnection and the like, protection of a direct current transmission line is especially important to ensure the safety and reliability of a power system. The high-voltage direct-current transmission line often passes through complex terrains and operates in an extreme climatic environment, the fault occurrence probability is high, and the safe and reliable operation of a direct-current transmission system is seriously threatened. Therefore, protection of the hvdc transmission line is essential to ensure reliability and safety of modern power transmission systems.
At present, a high-voltage direct-current transmission line mostly uses traveling wave protection and differential under-voltage protection as main protection, and current differential protection as backup protection. However, the traveling wave protection and the differential undervoltage protection have the problems of high sampling frequency, low sensitivity in the case of high transition resistance fault and the like. The current differential protection is used as a backup protection for detecting high-resistance faults, and in order to avoid the influence of capacitance current, the action time delay reaches more than hundreds of milliseconds. In this delay phase, if the converter valve group protection is prior to the current differential protection, the pole will be stopped. Therefore, the current differential protection may not function as a backup protection, and the above-described situation may occur in actual engineering.
Aiming at the problems of the protection of the direct current line at present, a plurality of scholars mainly study the protection of the high-voltage direct current transmission line. The Fault analysis and tracking-wave protection scheme for bipolar HVDC lines proposes new high-speed traveling wave protection, but is susceptible to interference and high impedance. The high-voltage direct-current transmission line full-line quick-action protection utilizing filter branch current judges whether the amplitude of single-end current under a specific frequency band exceeds a set threshold to judge whether the fault occurs inside or outside a region, but when the far end of a longer line fails, the protection sensitivity may not meet the requirement. A new principle of high-voltage direct-current transmission line current differential protection provides a differential protection method based on a Bergeron distribution parameter model, but data at two ends are required to be strictly synchronous. A transition protection scheme for HVDC transmission line and Novel pilot protection scheme for high-voltage direct current transmission line based on fault current characteristics provide a new tandem protection scheme according to transient energy and fault current difference at two ends of rectifying side and inverting side during internal and external faults respectively, but both ends of the fault current characteristics need to be synchronized, and sensitivity and reliability are insufficient during high-transition resistance faults. Therefore, in order to ensure the reliability and the safety of the direct current transmission line, the research on a new high-voltage direct current transmission line protection method has very important significance.
Disclosure of Invention
Aiming at the problems, the invention provides a pilot protection method of a high-voltage direct-current transmission line based on the voltage characteristic of a smoothing reactor. The method is based on the voltage transient characteristics of the smoothing reactors during the internal and external faults of the direct current transmission system area, constructs a new pilot protection criterion of the high-voltage direct current transmission line to identify the internal and external faults of the direct current transmission line area, overcomes the defects of the traditional high-voltage direct current transmission line main protection, does not need data synchronization at two ends, and is low in sampling frequency, simple in operation and easy to realize. The technical scheme of the invention is as follows:
A pilot protection method for a high-voltage direct-current transmission line based on smoothing reactor voltage mainly utilizes the sudden change directions of the smoothing reactor voltage at the rectifying side and the smoothing reactor voltage at the inverting side of the high-voltage direct-current transmission line to realize the discrimination of faults inside and outside a region, and comprises the following steps:
(1) The voltages at two ends of the smoothing reactor at the rectifying side and the smoothing reactor at the inverting side of the direct current circuit are acquired through a voltage acquisition device, and the voltage uMp of the smoothing reactor at the rectifying side of the positive circuit, the voltage uMn of the smoothing reactor at the rectifying side of the negative circuit, the voltage uNp of the smoothing reactor at the inverting side of the positive circuit, the voltage uNn of the smoothing reactor at the inverting side of the negative circuit, the voltage uM of the smoothing reactor at the rectifying side and the voltage uN of the smoothing reactor at the inverting side are calculated.
(2) and respectively judging mutation directions pM and pN of the smoothing reactor voltage uM and the smoothing reactor voltage uN on the rectifying side and the inverting side.
(3) The method for identifying the faults inside and outside the region by utilizing the sudden change directions pM and pN of the voltage of the smoothing reactor and carrying out fault pole selection on the faults inside the region comprises the following steps: if the voltage abrupt change directions of the smoothing reactors on the rectifying side and the inverting side are positive directions, namely pM is 1 and pN is 1, the fault is a fault in the direct-current line area; if the sudden change direction of the voltage of the smoothing reactor on the rectifying side is a negative direction and the sudden change direction of the voltage of the smoothing reactor on the inverting side is a positive direction, namely pM is-1 and pN is 1, determining that the fault is an out-of-zone fault on the rectifying side; if the sudden change direction of the voltage of the smoothing reactor on the rectifying side is a positive direction and the sudden change direction of the voltage of the smoothing reactor on the inverting side is a negative direction, namely pM is equal to 1 and pN is equal to-1, the fault is judged to be an out-of-area fault on the inverting side.
In the step (2), the sudden change directions pM and pN of the voltage of the smoothing reactors on the rectifying side and the inverting side are judged, and the formula is used as follows
In the formula, pi-1 indicates that the abrupt change direction of the i-side smoothing reactor voltage is a positive direction, and pi-1 indicates that the abrupt change direction of the i-side smoothing reactor voltage is a negative direction; m, N are taken as i, and respectively represent a rectifying side and an inverting side; NT is the number of sampling points within 5ms of the data window length; k is an integer, 1, 2, 3, … …, NT; uM (k) is a time domain sampling value of smoothing reactor voltage uM at the rectifying side, and uN (k) is a time domain sampling value of smoothing reactor voltage uN at the inverting side; and the uset is a setting value, and 0.02UN is selected by considering the measurement error of the direct current sensor, wherein the UN is the rated voltage of the direct current system.
In the step (1), for the positive power transmission line, the positive voltage direction of the smoothing reactor on the rectifying side points to the positive line from the rectifying station, and the positive voltage direction of the smoothing reactor on the inverting side points to the positive line from the inverting station; for the negative pole transmission line, the positive voltage direction of the smoothing reactor on the rectifying side points to the rectifying station from the negative pole line, and the positive voltage direction of the smoothing reactor on the inverting side points to the inverting station from the negative pole line.
The rectifying side smoothing reactor voltage uM is the sum of the positive line rectifying side smoothing reactor voltage uMp and the negative line rectifying side smoothing reactor voltage uMn; the inverter-side smoothing reactor voltage uN is the sum of the positive line inverter-side smoothing reactor voltage uNp and the negative line inverter-side smoothing reactor voltage uNn.
The invention provides a pilot protection method for a high-voltage direct-current transmission line based on voltage characteristics of a smoothing reactor, aiming at the defects of the traditional high-voltage direct-current transmission line protection. Compared with the prior art, the method has the following advantages:
(1) The method realizes the discrimination of the internal and external faults by utilizing the abrupt change direction characteristics of the voltage of the smoothing reactor, and does not need the data synchronization of two ends.
(2) The pilot protection method for the high-voltage direct-current transmission line is provided based on the sudden change direction difference of the voltage of the smoothing reactor when the direct-current transmission system has internal and external faults, the protection theory is complete, and the selectivity is good.
(3) Compared with the prior art, the method is not influenced by the line distribution parameters and is resistant to high resistance.
(4) The fault identification is carried out by utilizing the abrupt change direction of the voltage of the smoothing reactor, and the sampling frequency requirement of the protection device is low by utilizing the voltage signal of the smoothing reactor, so the method has the characteristics of low requirement on hardware and easy realization.
drawings
Fig. 1 a schematic diagram of a bipolar hvdc transmission system.
fig. 2 an equivalent circuit of a high voltage direct current transmission system.
The system fault addition circuit in case of a fault in the area of fig. 3.
Fig. 4 extra circuitry for system failure in case of an out-of-area failure.
the reference numbers in the figures illustrate:
In fig. 1, f3 and f4 are unipolar and bipolar faults in the direct current transmission line area respectively; f1 and f2, f5 and f6 are respectively the fault outside the rectifying side and the inverter side; uMp, uMn, uNp and uNn are the voltages of the M end and the N end shunt reactors of the positive electrode circuit and the negative electrode circuit respectively; for the positive line, up1 and up2, up3 and up4 are the voltage of the measuring points on the two sides of the smoothing reactor on the rectifying side and the smoothing reactor on the inverting side respectively; for the negative electrode, un1 and un2, un3 and un4 are the measured point voltages on both sides of the smoothing reactor on the rectifying side and the smoothing reactor on the inverting side, respectively.
Fig. 2 (a) is a positive electrode equivalent circuit of the high-voltage direct-current transmission system; (b) the figure is a negative electrode equivalent circuit of the high-voltage direct-current transmission system; uR and uI are equivalent direct-current voltage sources of a rectification side converter, an inversion side converter and an alternating-current system respectively; uMp, uMn, uNp and uNn are the voltages of the M end and the N end shunt reactors of the positive electrode circuit and the negative electrode circuit respectively; LM and LN are equivalent impedances of a current converter at the rectifying side and the inverting side and an alternating current system respectively; lsr is smoothing reactor inductance; r1 and R2, L1 and L2, C are equivalent lumped parameter resistance, inductance, capacitance of the direct current line respectively.
fig. 3(a) is an equivalent circuit added to a system fault in the case of an inter-electrode fault; (b) the figure is an additional equivalent circuit of the system fault when the anode has a fault; the delta iM and the delta iN are transient current abrupt variables of the smoothing reactor on the rectifying side and the smoothing reactor on the inverting side respectively; uf is a voltage source superposed with a fault point; rf is the fault point transition resistance.
FIG. 4(a) is an additional equivalent circuit of system fault when the rectifying side out-of-zone fault occurs; (b) the figure is an additional equivalent circuit of system fault when the outside of the inversion side area is in fault; and iC is equivalent capacitance discharge current of the direct current transmission line.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
a pilot protection method for a high-voltage direct-current transmission line based on voltage characteristics of a smoothing reactor mainly utilizes the sudden change directions of the voltage of the smoothing reactor on the rectifying side and the voltage of the smoothing reactor on the inverting side of the high-voltage direct-current transmission line to realize the discrimination of faults inside and outside a region, and comprises the following specific steps:
(1) Fig. 1 is a schematic diagram of a high-voltage direct-current transmission system specifically applied in this embodiment. The voltages at two ends of the smoothing reactor at the rectifying side and the inverting side of the direct current circuit are acquired by a voltage acquisition device, and the voltage uMp of the smoothing reactor at the rectifying side of the positive circuit, the voltage uMn of the smoothing reactor at the rectifying side of the negative circuit, the voltage uNp of the smoothing reactor at the inverting side of the positive circuit, the voltage uNn of the smoothing reactor at the inverting side of the negative circuit, the voltage uM of the smoothing reactor at the rectifying side and the voltage uN of the smoothing reactor at the inverting side are calculated by a data processing device.
(2) And respectively judging mutation directions pM and pN of the smoothing reactor voltage uM and the smoothing reactor voltage uN on the rectifying side and the inverting side.
(3) And identifying the faults inside and outside the region by using the sudden change directions pM and pN of the voltage of the smoothing reactor, and performing fault pole selection on the faults inside the region.
In the step (1), for the positive power transmission line, the positive voltage direction of the smoothing reactor on the rectifying side points to the positive line from the rectifying station, and the positive voltage direction of the smoothing reactor on the inverting side points to the positive line from the inverting station; for the negative pole transmission line, the positive voltage direction of the smoothing reactor on the rectifying side points to the rectifying station from the negative pole line, and the positive voltage direction of the smoothing reactor on the inverting side points to the inverting station from the negative pole line.
In the step (1), the rectifying side smoothing reactor voltage uM is the sum of the positive line rectifying side smoothing reactor voltage uMp and the negative line rectifying side smoothing reactor voltage uMn; the inverter-side smoothing reactor voltage uN is the sum of the positive line inverter-side smoothing reactor voltage uNp and the negative line inverter-side smoothing reactor voltage uNn.
In the step (2), the sudden change directions pM and pN of the voltage of the smoothing reactors on the rectifying side and the inverting side are judged, and the formula is used as follows
In the formula, pi-1 indicates that the abrupt change direction of the i-side smoothing reactor voltage is a positive direction, and pi-1 indicates that the abrupt change direction of the i-side smoothing reactor voltage is a negative direction; m, N are taken as i, and respectively represent a rectifying side and an inverting side; NT is the number of sampling points within 5ms of the data window length; k is an integer, 1, 2, 3, … …, NT; uM (k) is a time domain sampling value of smoothing reactor voltage uM at the rectifying side, and uN (k) is a time domain sampling value of smoothing reactor voltage uN at the inverting side; and the uset is a setting value, and 0.02UN is selected by considering the measurement error of the direct current sensor, wherein the UN is the rated voltage of the direct current system.
In the step (3), if the voltage abrupt change directions of the smoothing reactors on the rectifying side and the inverting side are positive directions, namely pM is 1 and pN is 1, the fault is a fault in the direct-current line area; if the sudden change direction of the voltage of the smoothing reactor on the rectifying side is a negative direction and the sudden change direction of the voltage of the smoothing reactor on the inverting side is a positive direction, namely pM is-1 and pN is 1, determining that the fault is an out-of-zone fault on the rectifying side; if the sudden change direction of the voltage of the smoothing reactor on the rectifying side is a positive direction and the sudden change direction of the voltage of the smoothing reactor on the inverting side is a negative direction, namely pM is equal to 1 and pN is equal to-1, the fault is judged to be an out-of-area fault on the inverting side.
In the step (3), the identification of the faults inside and outside the region is realized based on the mutation directions pM and pN of the smoothing reactor voltage, and the principle is as follows:
An equivalent circuit of a high voltage direct current transmission system is shown in fig. 2. When the inter-pole fault occurs in the region, an equivalent circuit is added to the fault of the high-voltage direct-current power transmission system, as shown in fig. 3 (a).
From FIG. 3(a), it can be obtained from Kirchhoff's Voltage Law (KVL)
When an interelectrode fault occurs iN a high-voltage direct-current transmission system, transient current break variables delta iM and delta iN of the smoothing reactor are rapidly increased, and the transient current break variables delta iM and delta iN can be obtained by simplifying formula (1)
Therefore, transient abrupt voltage Δ uMp, Δ uMn, Δ uNp, Δ uNn of the smoothing reactor on the rectifying side and the smoothing reactor on the inverting side of the positive and negative lines
As can be seen from equation (3), when there is an inter-zone fault, all of the smoothing reactor transient sudden change voltages Δ uMp, Δ uNp, Δ uMp, and Δ uNp on the positive and negative dc transmission lines are sudden positive changes.
When a single pole (positive pole) in a zone is in ground fault, the fault-added equivalent circuit is shown in fig. 3 (b).
The same can be obtained from the fault-added equivalent circuit shown in FIG. 3(b)
Therefore, the abrupt voltages Δ uMp, Δ uNp of the smoothing reactors on the rectifying side and the inverting side
As can be seen from equations (3) and (5), when an in-zone fault occurs, the smoothing reactor abrupt voltage on the inverter side and the rectifier side of the faulty line is abruptly changed in the forward direction.
Fig. 4(a) and 4(b) show the additional equivalents of the fault when the rectifying side and the inversion station are out of zone. For an out-of-range fault, transient current break variables delta iM and delta iN of the smoothing reactor and capacitance current iC have the following relationship
as can be seen from equation (6), the equivalent capacitor discharge current iC of the dc transmission line does not change the abrupt change direction of the transient current abrupt change Δ iM and Δ iN.
From FIG. 4(a), the Kirchhoff Voltage Law (KVL) can be obtained
During the transient state of the fault, the transient state current of the smoothing reactor on the rectifying side is reduced, and the delta iM abrupt change direction is negative; transient current of the smoothing reactor on the inverting side is increased, and the delta iN abrupt change direction is a forward direction. Therefore, when the rectifying side out of the zone fails, the sudden change voltages Δ uMp and Δ uNp of the rectifying side and inverter side smoothing reactors
In the same way, when the inverter side has an external fault, the sudden change voltages delta uMp and delta uNp of the smoothing reactors on the rectifying side and the inverter side
Δu＞0 and Δu＜0 (9)
According to the formulas (6), (8) and (9), for the out-of-range fault, the abrupt change directions of the smoothing reactor voltage on the rectifying side and the smoothing reactor voltage on the inverting side are not influenced by the capacitance current of the direct current transmission line; when an external fault of the rectifying side occurs, the sudden change voltage of the smoothing reactor at the rectifying side is a negative sudden change, and the sudden change voltage of the smoothing reactor at the inverting side is a positive sudden change; when an external fault of the inversion side occurs, the sudden change voltage of the smoothing reactor on the rectification side is positive sudden change, and the sudden change voltage of the smoothing reactor on the inversion side is negative sudden change.
Therefore, for the faults in the high-voltage direct-current transmission line area, no matter the faults are the inter-pole faults or the single-pole (positive pole or negative pole) grounding faults, the transient voltages of the smoothing reactors on the rectifying side and the inverting side are all positive sudden changes; for an out-of-range fault, the transient voltage of the smoothing reactor on the fault side is in a negative sudden change, and the transient voltage of the smoothing reactor on the non-fault side is in a positive sudden change. Therefore, pilot protection criteria of the high-voltage direct-current transmission line can be constructed according to the difference of transient voltage mutation directions of the smoothing reactors on the rectifying side and the smoothing reactors on the inverting side during the faults inside and outside the area.
Because the voltage mutation directions of the smoothing reactor on the current side are respectively identified by the rectification side protection and the inversion side protection, and then the fault type is determined according to the voltage mutation directions of the smoothing reactor. Therefore, the protection method does not need the synchronization of data at two ends, and the protection data transmission channel only needs to transmit the judgment result of the voltage mutation direction of the smoothing reactor.
In this embodiment, a ± 800kV forward dam ultrahigh voltage direct current transmission system is built by using a PSCAD/EMTDC software, as shown in fig. 1. The overall length of the direct current transmission line is 1907km, and a frequency correlation model is adopted; the sampling frequency was 10 kHz.
1) In-zone fault
In order to verify the influence of the fault distance, the transition resistance, etc. on the protection scheme, the simulation results are shown in table 1. As can be seen from table 1, after a fault, the voltages of the smoothing reactors on the rectifying side and the inverting side are both increased, the mutation direction is a positive direction, the protection is judged to be an in-zone fault, and the protection has high sensitivity and reliability and is not influenced by the fault distance; the protection enables accurate identification of the fault type at high transition resistances.
TABLE 1 results of in-zone fault simulation for different fault distances
2) Out-of-range fault
To further verify the applicability and reliability of the protection, the results of the out-of-area fault simulation for different fault types are shown in table 2. As can be seen from table 2, the protection method of the present invention still has high reliability for various types of out-of-range faults.
TABLE 2 simulation results for different types of out-of-area faults
3) Influence of sampling frequency
Simulation results of the end-of-line fault f3 and the out-of-band f5 faults at different sampling frequencies are shown in table 3. As can be seen from table 3, when the sampling frequency is reduced, the smoothing filter voltage value is slightly reduced, but the simulation result shows that the protection can accurately determine the fault type. Therefore, the sampling frequency of not less than 2000Hz can meet the requirement of the protection method of the invention.
TABLE 3 simulation results at different sampling frequencies
Although the specific embodiments of the present invention have been described with reference to specific examples, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive faculty based on the technical solutions of the present invention.
Claims (4)
1. a pilot protection method for a high-voltage direct-current transmission line based on smoothing reactor voltage mainly utilizes the sudden change directions of the smoothing reactor voltage at the rectifying side and the smoothing reactor voltage at the inverting side of the high-voltage direct-current transmission line to realize the discrimination of faults inside and outside a region, and comprises the following steps:
(1) Acquiring voltages at two ends of a rectifying side and an inverting side smoothing reactor of a direct-current circuit through a voltage acquisition device, and calculating a voltage uMp of the rectifying side smoothing reactor of a positive circuit, a voltage uMn of the rectifying side smoothing reactor of a negative circuit, a voltage uNp of the inverting side smoothing reactor of the positive circuit, a voltage uNn of the inverting side smoothing reactor of the negative circuit, a voltage uM of the rectifying side smoothing reactor and a voltage uN of the inverting side smoothing reactor;
(2) Respectively judging mutation directions pM and pN of smoothing reactor voltages uM and uN at a rectifying side and an inverting side, and utilizing the following formulas:
In the formula, pi-1 indicates that the abrupt change direction of the i-side smoothing reactor voltage is a positive direction, and pi-1 indicates that the abrupt change direction of the i-side smoothing reactor voltage is a negative direction; m, N are taken as i, and respectively represent a rectifying side and an inverting side; NT is the number of sampling points within 5ms of the data window length; k is an integer, 1, 2, 3, … …, NT; uM (k) is a time domain sampling value of smoothing reactor voltage uM at the rectifying side, and uN (k) is a time domain sampling value of smoothing reactor voltage uN at the inverting side; uset is a setting value, and UN is the rated voltage of the direct current system;
(3) The method for identifying the faults inside and outside the region by utilizing the sudden change directions pM and pN of the voltage of the smoothing reactor and carrying out fault pole selection on the faults inside the region comprises the following steps: if the voltage abrupt change directions of the smoothing reactors on the rectifying side and the inverting side are positive directions, namely pM is 1 and pN is 1, the fault is a fault in the direct-current line area; if the sudden change direction of the voltage of the smoothing reactor on the rectifying side is a negative direction and the sudden change direction of the voltage of the smoothing reactor on the inverting side is a positive direction, namely pM is-1 and pN is 1, determining that the fault is an out-of-zone fault on the rectifying side; if the sudden change direction of the voltage of the smoothing reactor on the rectifying side is a positive direction and the sudden change direction of the voltage of the smoothing reactor on the inverting side is a negative direction, namely pM is equal to 1 and pN is equal to-1, the fault is judged to be an out-of-area fault on the inverting side.
2. The pilot protection method according to claim 1, wherein in the step (1), for the positive transmission line, the positive voltage direction of the smoothing reactor on the rectifying side is from the rectifying station to the positive line, and the positive voltage direction of the smoothing reactor on the inverting side is from the inverting station to the positive line; for the negative pole transmission line, the positive voltage direction of the smoothing reactor on the rectifying side points to the rectifying station from the negative pole line, and the positive voltage direction of the smoothing reactor on the inverting side points to the inverting station from the negative pole line.
3. The pilot protection method according to claim 1, wherein in step (1), the rectifying-side smoothing reactor voltage uM is the sum of a positive line rectifying-side smoothing reactor voltage uMp and a negative line rectifying-side smoothing reactor voltage uMn; the inverter-side smoothing reactor voltage uN is the sum of the positive line inverter-side smoothing reactor voltage uNp and the negative line inverter-side smoothing reactor voltage uNn.
4. The pilot protection method according to claim 1, wherein in the step (2), the uset is selected to be 0.02UN in consideration of the measurement error of the dc sensor.
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| CN113589101A (en) * | 2021-07-30 | 2021-11-02 | 华北水利水电大学 | Fault location method and system suitable for direct-current power transmission system |
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| CN102255293B (en) * | 2011-07-26 | 2014-04-23 | 西安交通大学 | Single-ended electrical quantity full-line quick-action protection method for recognizing faults inside and outside high-voltage direct-current transmission line region |
| CN102510050A (en) * | 2011-11-08 | 2012-06-20 | 西安交通大学 | Pilot protection method for direct current line current abrupt change of multi-terminal direct current transmission system |
| CN202513564U (en) * | 2012-03-08 | 2012-10-31 | 昆明理工大学 | Single-ended transient voltage protection device of ultra-high voltage direct current (DC) transmission line |
| CN102820643B (en) * | 2012-08-20 | 2014-09-17 | 山东大学 | High voltage direct current power transmission line protection method based on voltage and current mutation direction |
| CN105548819B (en) * | 2016-02-19 | 2018-03-20 | 国网四川省电力公司电力科学研究院 | A kind of HVDC transmission line internal fault external fault recognition methods based on anti-traveling wave |
| CN106058828B (en) * | 2016-07-18 | 2018-05-15 | 天津大学 | A kind of multiterminal flexible direct current power network line direction pilot protection method |
| CN106253240B (en) * | 2016-07-27 | 2019-01-11 | 天津大学 | Multiterminal flexible direct current network system Non-unit protection method based on borderline properties |
| CN106505536B (en) * | 2016-11-22 | 2019-01-11 | 三峡大学 | A kind of UHVDC Transmission Lines guard method based under distributed parameter model using current break characteristic |
| CN106711969B (en) * | 2017-01-17 | 2018-11-23 | 西安科技大学 | Bipolar HVDC method for pilot protection of circuit based on modulus mutation |
| CN107681641B (en) * | 2017-08-01 | 2019-01-15 | 华北电力大学 | Multiterminal flexible direct current power grid boundary protection method based on direct current reactor voltage |
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2018
- 2018-04-10 CN CN201810316509.5A patent/CN108808634B/en not_active Expired - Fee Related
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