CN114696301A - Double-fed wind power plant output line single-phase grounding protection method and system - Google Patents

Double-fed wind power plant output line single-phase grounding protection method and system Download PDF

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CN114696301A
CN114696301A CN202011642798.1A CN202011642798A CN114696301A CN 114696301 A CN114696301 A CN 114696301A CN 202011642798 A CN202011642798 A CN 202011642798A CN 114696301 A CN114696301 A CN 114696301A
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wind power
mode
reference voltage
fault
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孔祥敏
孟长虹
史卓鹏
王亚臣
李勇
张亮红
郑惠文
李艳
魏佳红
刘丽花
赵利军
王凯凯
康静雅
马静
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Economic and Technological Research Institute of State Grid Shanxi Electric Power Co Ltd
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Economic and Technological Research Institute of State Grid Shanxi Electric Power Co Ltd
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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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
    • H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac 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
    • 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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  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention relates to a single-phase ground protection method and a single-phase ground protection system for a sending-out line of a double-fed wind power plant, wherein the method comprises the following steps: acquiring electrical data including zero-mode voltage of a wind power side and a system side of a transmitting line of a double-fed wind power plant; calculating the reference voltage of the single-phase earth fault inside and/or outside the wind power side area of the transmission line and the reference voltage of the single-phase earth fault inside and/or outside the system side area based on the zero-modulus component equivalent network model; when the earth fault is judged, comparing the difference between the actually acquired zero-mode voltage and the reference voltage, and judging whether the preset pilot protection action criterion is met; if the action criterion is met, judging that the fault is in the area, and immediately sending a tripping signal; if the action criterion is not met, the fault is judged to be an out-of-area fault, and no trip signal is sent. Under the condition of double-fed wind power plant fault current frequency deviation, the method can avoid the influence of rotating speed frequency components on the protection criterion, and realize the accurate identification of the faults inside and outside the sending-out line area of the double-fed wind power plant.

Description

Double-fed wind power plant output line single-phase grounding protection method and system
Technical Field
The invention belongs to the technical field of relay protection, and particularly relates to a single-phase ground protection method and system for a double-fed wind power plant output line.
Background
With the continuous access of wind power generation to a power grid, the natural randomness of wind energy makes the relay protection problem of a wind power plant more and more prominent. The electromagnetic transient characteristics of a wind power generation centralized access regional power grid and a traditional power grid during a fault period are obviously different, and the research on a power grid protection principle suitable for wind power plant access has great significance on system safety.
At present, the protection of a wind power transmission line still adopts the protection configuration of a conventional power transmission line, and pilot protection is equipped as main protection of the line, so that the special problem of wind power transmission is not considered. After the double-fed wind turbine generator has an external fault, the generator-end fault current is approximately composed of three parts, namely a steady-state alternating current component, an attenuated direct current component and an attenuated alternating current component. Under the influence of the rotating speed frequency component on the power frequency phasor extraction precision, the protection of the power frequency full-quantity structure is applied to the problem of reduced action performance and even false failure when the circuit is sent out from the double-fed wind power plant.
Disclosure of Invention
In view of the analysis, the invention aims to disclose a double-fed wind power plant output line single-phase grounding protection method and system, and solve the problem that faults of a wind power output line are difficult to accurately identify.
The invention discloses a double-fed wind power plant outgoing line single-phase grounding protection method, which comprises the following steps:
acquiring electrical data including zero-mode voltage of a wind power side and a system side of a transmitting line of a double-fed wind power plant;
calculating the reference voltage of the single-phase earth fault inside and/or outside the wind power side area of the transmission line and the reference voltage of the single-phase earth fault inside and/or outside the system side area based on the zero-modulus component equivalent network model;
when the ground fault judgment is carried out, the actually acquired zero-mode voltage of the wind power side of the transmitting line is compared with the reference voltage of the single-phase ground fault in the wind power side area and/or outside the wind power side area, and the zero-mode voltage of the system side is compared with the reference voltage of the single-phase ground fault in the system side area and/or outside the wind power side area; judging whether the comparison result meets a preset pilot protection action criterion or not; if the single-phase earth fault meets the action criterion, judging that the single-phase earth fault is in the area, and immediately sending a tripping signal; if the action criterion is not met, the out-of-area single-phase earth fault is judged, and no tripping signal is sent.
Further, reference voltage of single-phase earth fault in wind power side area
Figure BDA0002872945440000021
In the formula, Lw0Sending out the equivalent zero-mode inductance of the transformer for the wind power plant; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
Further, reference voltage of single-phase earth fault outside wind power side area
Figure BDA0002872945440000022
In the formula, Rs0、Ls0Respectively an equivalent zero-mode resistance and a zero-mode inductance of the alternating current system; rl0、Ll0Respectively a zero-mode resistor and a zero-mode inductor of the wind power output line; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
Further, the reference voltage of the single-phase earth fault in the system side region
Figure BDA0002872945440000023
In the formula, Rs0、Ls0Respectively an equivalent zero-mode resistance and a zero-mode inductance of the alternating current system; i.e. is0Is the zero mode current of the system side, and t is the time.
Further, the reference voltage of the single-phase earth fault outside the system side region
Figure BDA0002872945440000024
In the formula, Rl0、Ll0Zero mode resistance and zero mode inductance, L, of the wind power outgoing line, respectivelyw0Sending out the equivalent zero-mode inductance of the transformer for the wind power plant; i all right anglew0Is the zero mode current of the wind power side, and t is the time.
Further, the difference between the zero-mode voltage of the wind power side and the reference voltage of the in-zone and/or out-zone single-phase ground fault and the difference between the zero-mode voltage of the system side and the reference voltage of the in-zone and/or out-zone single-phase ground fault are measured by adopting a zero-mode model similarity factor;
the similarity factor calculation formula is as follows:
Figure BDA0002872945440000025
in the formula, kwA zero-mode model similarity factor for the wind-power side of the outgoing line; k is a radical ofsA zero-mode model similarity factor for the system side of the outgoing line; u. ofw0For wind power side zero mode voltage actual measurementVector of values, u'w0Is a reference voltage vector u of the wind power side of the wind power transmission lines0Vector u 'formed by actual sampling value of system side zero mode voltage's0And the reference voltage vector of the wind power transmission line system side is obtained.
Further, the reference voltage vector of the wind power side of the wind power transmission line
Figure BDA0002872945440000031
i'w0The actual measured value of the zero-mode current is corresponding to the actual measured value of the zero-mode voltage at the wind power side;
reference voltage vector of wind power transmission line system side
Figure BDA0002872945440000032
i′s0Is the actual measured value of the zero-mode current corresponding to the actual measured value of the zero-mode voltage on the system side.
Further, the reference voltage vector of the wind power side of the wind power transmission line
Figure BDA0002872945440000033
i'w0The measured value is a zero-mode current actual measured value corresponding to a zero-mode voltage actual measured value at the wind power side;
reference voltage vector of wind power transmission line system side
Figure BDA0002872945440000034
i′s0Is the actual measured value of the zero-mode current corresponding to the actual measured value of the zero-mode voltage on the system side.
Further, the protection action criterion is as follows:
Figure BDA0002872945440000035
in the formula ksetIs a predetermined protection threshold.
The invention also discloses a double-fed wind power plant output line single-phase grounding protection system, which comprises a data acquisition module, a protection calculation module and a protection action module;
the data acquisition module is used for acquiring electrical data including zero-mode voltage on the wind power side of the output line and the system side of the double-fed wind power plant and transmitting the electrical data to the protection calculation module;
the protection calculation module is used for calculating the reference voltage of the single-phase earth fault inside and/or outside the wind power side area of the transmission line and the reference voltage of the single-phase earth fault inside and/or outside the system side area; calculating the zero-mode voltage similarity factor of the wind power side and the system side of the transmission line according to the input electrical data, and transmitting the zero-mode voltage similarity factor to the protection action module;
the protection action module is used for receiving the zero-mode voltage similarity factors at two sides of the circuit, judging whether the similarity factors meet the pilot protection action criterion, if so, judging that the fault is in the area, and immediately sending a trip signal; if the action criterion is not met, the fault is judged to be an out-of-area fault, and no trip signal is sent.
The invention can realize at least one of the following beneficial effects:
according to the single-phase ground protection method and system for the double-fed wind power plant outgoing line, the influence of the rotating speed frequency component on the protection criterion can be avoided under the condition of double-fed wind power plant fault current frequency deviation according to model difference characteristics when faults occur at different positions inside and outside the region, and the accurate identification of the double-fed wind power plant outgoing line region internal and external faults is achieved.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
Fig. 1 is a flowchart of a single-phase ground protection method for a transmission line of a doubly-fed wind farm in a first embodiment;
fig. 2 is a schematic diagram of an equivalent zero-mode network model of a line fault of a wind farm in the first embodiment;
fig. 3 is a schematic diagram of a single-phase ground protection system of a transmission line of a doubly-fed wind farm in the first embodiment;
fig. 4 is a schematic view of a wind power output system in the second embodiment;
fig. 5 is a zero-mode voltage similarity factor graph when a single-phase ground fault occurs in a transmission line area of the wind farm in the second embodiment;
fig. 6 is a zero-mode voltage similarity factor graph of the wind power receiving end ac system in the second embodiment during a single-phase ground fault;
fig. 7 is a zero-mode voltage similarity factor graph in the case of a single-phase ground fault inside the wind farm in the second embodiment.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.
Example one
An embodiment of the invention discloses a double-fed wind power plant outgoing line single-phase grounding protection method, which comprises the following steps as shown in fig. 1:
s1, collecting electrical data of a wind power side and a system side of a sending line of the double-fed wind power plant;
the acquired actually-measured electrical data comprise zero-mode voltage and zero-mode current of a wind power side of a double-fed wind power plant output line and zero-mode voltage and zero-mode current of a system side.
Step S2, calculating virtual zero-mode voltages of a wind power side and a system side of a sending line based on a zero-mode component equivalent network model, and taking the virtual zero-mode voltages as reference voltages for judging faults at different positions inside and outside a region;
specifically, the calculated virtual zero mode voltage comprises reference voltage of single-phase earth fault inside and/or outside a wind power side area of the transmission line and reference voltage of single-phase earth fault inside and/or outside a system side area;
the zero-modulus equivalent network model of the wind power output system of the embodiment is shown in fig. 2. Because the wind power plant sending-out transformer adopts a neutral point direct grounding connection method, the zero sequence equivalent inductance of the wind power plant only comprises the zero sequence inductance of the sending-out transformer. L isw0The equivalent zero-mode inductance of the transformer is sent out by the wind power plant; rs0、Ls0Equivalent zero mode power of AC system respectivelyResistance and zero mode inductance; rl0、Ll0Respectively a zero-mode resistor and a zero-mode inductor of the wind power output line; i.e. iw0、is0Respectively zero-mode current of a wind power side and zero-mode current of a system side; u. ofw0、us0The zero mode voltage of the wind power side and the zero mode voltage of the system side are respectively.
Calculating the reference voltage of the single-phase earth fault in the wind power side area according to the zero-modulus component equivalent network model
Figure BDA0002872945440000051
In the formula, Lw0Sending out the equivalent zero-mode inductance of the transformer for the wind power plant; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
Therefore, when a fault occurs in the wind power side protection area, the measured value of the zero-mode voltage at the protection installation position is the voltage drop on the inductor at the back side, namely the zero-mode voltage reflects the characteristics of the equivalent network model of the zero-mode component at the protection back side.
Calculating the reference voltage of the single-phase earth fault outside the wind power side area according to the zero-modulus component equivalent network model
Figure BDA0002872945440000052
In the formula, Rs0、Ls0Respectively an equivalent zero-mode resistance and a zero-mode inductance of the alternating current system; rl0、Ll0Respectively a zero-mode resistor and a zero-mode inductor of the wind power output line; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
Therefore, when the single-phase earth fault is out of the area, the measured value of the zero-mode voltage at the protection installation position is the voltage drop on the equivalent model of the transmission line and the wind power receiving end system, namely the zero-mode voltage reflects the characteristics of the zero-mode component equivalent network model of the opposite side system.
According to the zero-modulus component equivalent network model, the reference voltage of the single-phase earth fault in the system side area
Figure BDA0002872945440000061
In the formula, Rs0、Ls0Respectively an equivalent zero-mode resistance and a zero-mode inductance of the alternating current system; i.e. is0Is the zero mode current of the system side, and t is the time.
Therefore, when a single-phase earth fault occurs in the area, the measured value of the zero-mode voltage at the protection installation position is the voltage drop on the wind power receiving end system model at the back side, namely the zero-mode voltage reflects the characteristics of the zero-mode component equivalent network model for protecting the wind power receiving end alternating current system at the back side.
According to the zero-modulus component equivalent network model, the reference voltage of the single-phase earth fault outside the system side area
Figure BDA0002872945440000062
In the formula, Rl0、Ll0Zero mode resistance and zero mode inductance, L, of the wind power outgoing line, respectivelyw0Sending out the equivalent zero-mode inductance of the transformer for the wind power plant; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
Therefore, when the outside area is in fault, the zero-mode voltage measured value at the protection installation position is the voltage drop on the transmission line and the equivalent model of the wind power plant, namely the zero-mode voltage reflects the characteristics of the zero-mode component equivalent network model of the opposite side system.
Step S3, when judging the grounding fault, comparing the difference between the actually collected zero-mode voltage and the reference voltage, and judging whether the preset pilot protection action criterion is met; if the action criterion is met, judging that the fault is in the area, and immediately sending a tripping signal; if the action criterion is not met, the fault is judged to be an out-of-area fault, and no trip signal is sent.
Specifically, when the ground fault is judged, the actually acquired zero mode voltage of the wind power side of the transmitting line is compared with the reference voltage of the single-phase ground fault in the wind power side area and/or outside the area, and the zero mode voltage of the system side is compared with the reference voltage of the single-phase ground fault in the system side area and/or outside the area;
when a fault occurs in the transmission line area, the zero-mode voltage at the protection installation position of the wind power side and the system side reflects the zero-mode voltage drop of the system at the back side, and when a fault occurs outside the transmission line area, the zero-mode voltage at the protection installation position of the fault side reflects the zero-mode voltage drop of the system at the opposite side. And solving the virtual zero-mode voltage drop by using the back side system parameters, taking the voltage as a reference voltage, and judging the zero-mode model difference through the difference between the actually measured voltage and the reference voltage.
Furthermore, because the fluctuation degree of the zero-mode voltage value under different fault conditions is large, in order to facilitate setting, the sensitivity of a protection criterion is ensured, and meanwhile, the influence of errors introduced by differential calculation on the result is reduced;
the similarity factor calculation formula is as follows:
Figure BDA0002872945440000071
in the formula, kwA zero-mode model similarity factor for the wind-power side of the outgoing line; k is a radical ofsA zero-mode model similarity factor for the system side of the outgoing line; u. ofw0Vector u 'formed by actual measurement value of wind power side zero-mode voltage'w0Is a reference voltage vector u of the wind power side of the wind power transmission lines0Vector u 'formed by actual sampling value of system side zero mode voltage's0And the reference voltage vector of the wind power transmission line system side is obtained.
More specifically, reference voltage vector u 'on the wind power side of wind power transmission line'w0Reference voltage vector u 'on the wind power transmission line system side's0The following two schemes can be selected:
the first scheme is as follows:
reference voltage vector of wind power side of wind power supply line
Figure BDA0002872945440000072
i'w0The measured value is a zero-mode current actual measured value corresponding to a zero-mode voltage actual measured value at the wind power side;
reference voltage vector of wind power transmission line system side
Figure BDA0002872945440000073
i′s0Is the actual measured value of the zero-mode current corresponding to the actual measured value of the zero-mode voltage on the system side.
Scheme II:
reference voltage vector of wind power side of wind power transmission line
Figure BDA0002872945440000081
i'w0The actual measured value of the zero-mode current is corresponding to the actual measured value of the zero-mode voltage at the wind power side;
reference voltage vector of wind power transmission line system side
Figure BDA0002872945440000082
i′s0Is the actual measured value of the zero-mode current corresponding to the actual measured value of the zero-mode voltage on the system side.
Reference voltage vector u 'of wind power supply line wind power side adopting scheme one'w0Reference voltage vector u 'on the wind power transmission line system side's0The similarity factor is analyzed.
When a fault occurs in the sending line area, the zero-mode voltage measured value at the protection installation position is the voltage drop on the back side system model, uw0＝u’w0，us0＝u’s0Therefore, the measured voltage on both sides is the same as the reference voltage waveform, kw＝1，ks＝1。
When the wind power plant has an internal fault, the measured value of the zero-mode voltage at the protection installation position of the system side is the voltage drop u on the wind power receiving end alternating current model at the back sides0＝u’s0Therefore, the measured voltage on the system side is the same as the reference voltage waveform ks1. And the zero-mode voltage measured value at the wind power side protection installation position is the voltage drop u on the opposite side system modelw0≠u’w0Therefore, the measured voltage on the wind power side is different from the reference voltage waveform, kw<1。
When the wind power receiving end system fails, the zero-mode voltage measured value at the wind power side protection installation position is the voltage drop on the back side inductor, uw0＝u’w0So that the measured voltage on the wind side is the same as the reference voltage waveform kw1. And the zero mode voltage measurement value at the system side protection installation position is the opposite side systemVoltage drop across the model, us0≠u’s0Therefore, the system side measured voltage is different from the reference voltage waveform, ks<1。
The simulation data are obtained after simulation, and when the wind power plant has internal fault, the simulation data are 0.5<kw<1; when the wind power receiving end system has a fault, 0.5<ks<1。
Reference voltage vector u 'of wind power supply line wind power side adopting scheme two'w0Reference voltage vector u 'on the wind power transmission line system side's0Analysis of the similarity factor yields results similar to those described above.
Therefore, the protection action criterion constructed according to the analysis result is as follows:
Figure BDA0002872945440000091
in the formula ksetIs a predetermined protection threshold value, kset＝0.5。
When judging the grounding fault, if the calculated k iswOr ksExceeds a preset protection action threshold value ksetIf the fault is 0.5, judging that the fault is in the area, and immediately sending a tripping signal; if the action criterion is not met, the fault is judged to be an out-of-area fault, and no trip signal is sent.
In another aspect of the present embodiment, a dual-fed wind farm output line single-phase ground protection system is disclosed, as shown in fig. 3, including a data acquisition module, a protection calculation module, and a protection action module;
the device comprises a data acquisition module, a protection calculation module and a protection action module;
the data acquisition module is used for acquiring electrical data including zero-mode voltage at the wind power side and the system side of the output line of the doubly-fed wind power plant and transmitting the electrical data to the protection calculation module;
the protection calculation module is used for calculating the reference voltage of the single-phase earth fault inside and/or outside the wind power side area of the transmission line and the reference voltage of the single-phase earth fault inside and/or outside the system side area; calculating the zero-mode voltage similarity factor of the wind power side and the system side of the transmission line according to the input electrical data, and transmitting the zero-mode voltage similarity factor to the protection action module;
the protection action module is used for receiving the zero-mode voltage similarity factors at two sides of the circuit, judging whether the similarity factors meet the pilot protection action criterion, if so, judging that the fault is in the area, and immediately sending a trip signal; if the action criterion is not met, the fault is judged to be an out-of-area fault, and no trip signal is sent.
The technical details in this embodiment are the same as those in the previous embodiment, and are not repeated herein.
In summary, according to the scheme of this embodiment, according to model difference characteristics when faults occur at different positions inside and outside the area, under the condition of frequency deviation of fault current of the doubly-fed wind farm, the influence of the rotating speed frequency component on the protection criterion can be avoided, and accurate identification of faults inside and outside the sending line area of the doubly-fed wind farm is achieved.
Example two
In this embodiment, the whole wind farm is simulated by using the parallel equivalent model of the doubly-fed wind turbine, and the single-phase earth fault is determined by using the method and the system for single-phase earth fault protection of the transmission line of the doubly-fed wind farm in the first embodiment.
As shown in the wind power output system diagram of fig. 4, a wind farm is composed of 300 identical double-fed asynchronous fans which are connected in parallel, and each fan has a rated capacity of 1.5MW and operates according to rated output; the wind power station firstly passes through a transformer in the 0.69/20kV field and then passes through an 20/230kV transformer to send electric energy to a system through a wind power outlet wire. The main parameters of the wind power output system are shown in table 1.
TABLE 1 wind power delivery System principal parameters
Figure BDA0002872945440000101
The setting scene of the embodiment is as follows: and when t is 1.4s, single-phase earth faults respectively occur in the wind power plant sending-out line, the wind power receiving end alternating current system and the wind power plant, the faults last for 0.1s, and the transition resistance is 0 omega.
The judgment result by the embodiment method is as follows:
and measuring zero-mode current and zero-mode voltage values of a wind power side and a system side in the wind power output system, and calculating a similarity factor of the zero-mode voltage at two ends, as shown in fig. 5, 6 and 7. As can be seen from fig. 5, when an intra-area fault occurs, the zero-mode voltage similarity factors of the wind power side and the system side are both close to 1 and greater than the protection threshold value of 0.5, so that the protection acts correctly. As shown in fig. 6 and 7, when the wind power receiving end ac system fails, when t is 1.43s, the system-side zero-mode voltage similarity factor has a maximum value of-0.848, which is much smaller than the protection threshold value of 0.5. When the wind power plant has an internal fault, the t is 1.4s, the maximum value of the zero-mode voltage similarity factor on the wind power side is 0.166, and the t is far smaller than a protection threshold value. Therefore, the protection is reliable and does not operate when the outside is in fault.
The result of the second embodiment proves that the double-fed wind power plant outgoing line single-phase grounding protection method and system in the first embodiment can avoid the influence of the rotating speed frequency component on the protection criterion, and realize accurate identification of the internal and external faults of the double-fed wind power plant outgoing line area.
While the invention has been described with reference to specific preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims (10)

1. A double-fed wind power plant output line single-phase grounding protection method is characterized by comprising the following steps:
acquiring electrical data including zero-mode voltage of a wind power side and a system side of a transmitting line of a double-fed wind power plant;
calculating the reference voltage of the single-phase earth fault inside and/or outside the wind power side area of the transmission line and the reference voltage of the single-phase earth fault inside and/or outside the system side area based on the zero-modulus component equivalent network model;
when the ground fault is judged, comparing the actually acquired zero-mode voltage of the wind power side of the transmitting line with the reference voltage of the single-phase ground fault in the wind power side area and/or outside the area, and comparing the zero-mode voltage of the system side with the reference voltage of the single-phase ground fault in the system side area and/or outside the area; judging whether the comparison result meets a preset pilot protection action criterion or not; if the single-phase earth fault meets the action criterion, judging that the single-phase earth fault is in the area, and immediately sending a tripping signal; if the action criterion is not met, the out-of-area single-phase earth fault is judged, and no tripping signal is sent.
2. The double-fed wind farm outgoing line single-phase ground protection method according to claim 1, characterized in that,
reference voltage of single-phase earth fault in wind power side area
Figure FDA0002872945430000011
In the formula, Lw0Sending out the equivalent zero-mode inductance of the transformer for the wind power plant; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
3. The double-fed wind farm outgoing line single-phase grounding protection method according to claim 1,
reference voltage of single-phase earth fault outside wind power side area
Figure FDA0002872945430000012
In the formula, Rs0、Ls0Respectively an equivalent zero-mode resistance and a zero-mode inductance of the alternating current system; rl0、Ll0Respectively a zero-mode resistor and a zero-mode inductor of the wind power output line; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
4. The double-fed wind farm outgoing line single-phase grounding protection method according to claim 1,
reference voltage of single-phase earth fault in system side area
Figure FDA0002872945430000013
In the formula, Rs0、Ls0Equivalent zero mode resistance and zero of AC system respectivelyA mode inductor; i.e. is0Is the zero mode current of the system side, and t is the time.
5. The double-fed wind farm outgoing line single-phase grounding protection method according to claim 1,
reference voltage of single-phase earth fault outside system side area
Figure FDA0002872945430000021
In the formula, Rl0、Ll0Zero mode resistance and zero mode inductance, L, of the wind power outgoing line, respectivelyw0Sending out the equivalent zero-mode inductance of the transformer for the wind power plant; i.e. iw0Is the zero mode current of the wind power side, and t is the time.
6. The double-fed wind farm outgoing line single-phase grounding protection method according to claim 1,
measuring the difference between the zero-mode voltage of the wind power side and the reference voltage of the in-zone and/or out-zone single-phase ground fault and the difference between the zero-mode voltage of the system side and the reference voltage of the in-zone and/or out-zone single-phase ground fault by adopting a zero-mode model similarity factor;
the similarity factor calculation formula is as follows:
Figure FDA0002872945430000022
in the formula, kwA zero-mode model similarity factor for the wind-power side of the outgoing line; k is a radical ofsA zero-mode model similarity factor for the system side of the outgoing line; u. ofw0Vector u 'formed by actual measurement value of wind power side zero-mode voltage'w0Is a reference voltage vector u of the wind power side of the wind power transmission lines0Vector u 'formed by actual sampling value of system side zero mode voltage's0And the reference voltage vector of the wind power transmission line system side is obtained.
7. The double-fed wind farm outgoing line single-phase ground protection method according to claim 6,
reference voltage vector of wind power side of wind power transmission line
Figure FDA0002872945430000023
i'w0The actual measured value of the zero-mode current is corresponding to the actual measured value of the zero-mode voltage at the wind power side;
reference voltage vector of wind power transmission line system side
Figure FDA0002872945430000024
i′s0Is the actual measured value of the zero-mode current corresponding to the actual measured value of the zero-mode voltage on the system side.
8. The double-fed wind farm outgoing line single-phase ground protection method according to claim 6, characterized in that the reference voltage vector of the wind side of the wind power outgoing line
Figure FDA0002872945430000031
i'w0The actual measured value of the zero-mode current is corresponding to the actual measured value of the zero-mode voltage at the wind power side;
reference voltage vector of wind power transmission line system side
Figure FDA0002872945430000032
i′s0Is the actual measured value of the zero-mode current corresponding to the actual measured value of the system-side zero-mode voltage.
9. The double-fed wind farm outgoing line single-phase ground protection method according to claim 6,
the protection action criterion is as follows:
Figure FDA0002872945430000033
in the formula ksetIs a predetermined protection threshold.
10. A double-fed wind power plant output line single-phase grounding protection system is characterized by comprising a data acquisition module, a protection calculation module and a protection action module;
the data acquisition module is used for acquiring electrical data including zero-mode voltage at the wind power side and the system side of the output line of the doubly-fed wind power plant and transmitting the electrical data to the protection calculation module;
the protection calculation module is used for calculating the reference voltage of the single-phase earth fault inside and/or outside the wind power side area of the transmission line and the reference voltage of the single-phase earth fault inside and/or outside the system side area; calculating the zero-mode voltage similarity factor of the wind power side and the system side of the transmission line according to the input electrical data, and transmitting the zero-mode voltage similarity factor to the protection action module;
the protection action module is used for receiving the zero-mode voltage similarity factors at two sides of the circuit, judging whether the similarity factors meet the pilot protection action criterion, if so, judging that the fault is in the area, and immediately sending a trip signal; if the action criterion is not met, the fault is judged to be an out-of-area fault, and no trip signal is sent.
CN202011642798.1A 2020-12-30 2020-12-30 Double-fed wind power plant output line single-phase grounding protection method and system Pending CN114696301A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114899808A (en) * 2022-07-12 2022-08-12 国网江西省电力有限公司电力科学研究院 Grounding distance protection method and system for photovoltaic grid-connected tie line

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114899808A (en) * 2022-07-12 2022-08-12 国网江西省电力有限公司电力科学研究院 Grounding distance protection method and system for photovoltaic grid-connected tie line
CN114899808B (en) * 2022-07-12 2022-12-09 国网江西省电力有限公司电力科学研究院 Grounding distance protection method and system for photovoltaic grid-connected tie line

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