CN112054498A - Current-limiting protection method and device of ground fault full-compensation system - Google Patents

Current-limiting protection method and device of ground fault full-compensation system Download PDF

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CN112054498A
CN112054498A CN202011017379.9A CN202011017379A CN112054498A CN 112054498 A CN112054498 A CN 112054498A CN 202011017379 A CN202011017379 A CN 202011017379A CN 112054498 A CN112054498 A CN 112054498A
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phase
limiting protection
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CN112054498B (en
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刘红文
蔡晓斌
曾祥君
赵现平
王科
李文云
张恭源
聂鼎
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Electric Power Research Institute of Yunnan Power Grid Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H02H9/021—Current limitation using saturable reactors
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • 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
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers

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Abstract

The application provides a current-limiting protection method and a current-limiting protection device of a ground fault full-compensation system, wherein the method comprises the following steps: obtaining capacitance current I of power grid systemc(ii) a According to the capacitive current I of the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase(ii) a According to rated thermal short-circuit current IbaseCalculating the rated continuous current I of the current-limiting protection reactorE(ii) a According to rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL(ii) a According to rated reactance value X of current-limiting protection reactorLAnd rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has ground faults and the ground fault current full compensation system judges the ground fault phase wrongly, the current limiting reactor limits the ground fault current in the ground fault phase to be below a preset threshold value, and the safety of the power grid system is protected.

Description

Current-limiting protection method and device of ground fault full-compensation system
Technical Field
The present disclosure relates to the field of power systems, and in particular, to a current limiting protection method and device for a ground fault full compensation system.
Background
The single-phase earth fault of the power distribution network at home and abroad accounts for more than 80 percent, the safe operation of the power grid and equipment is seriously influenced, and the safe processing of the earth fault plays an important role in social and economic development. When the capacitance current of the system is more than 10A, an arc suppression coil grounding mode is adopted. The arc suppression coil can reduce the fault current to a certain extent, and the system can take the trouble to operate for 2 hours, but the arc suppression coil can not realize full compensation, and the fault point still has the residual current that is less than 10A, and the existence of residual current can cause the person to electrocute, the conflagration accident to and threaten the safe and stable operation of electric wire netting and equipment seriously. When the capacitance current of the system is large, a small-resistance grounding mode is mostly adopted, when a single-phase grounding fault occurs, the zero sequence current of the fault line is amplified, and the relay protection device quickly cuts off the fault line.
In order to thoroughly eliminate the damage of the single-phase earth fault and ensure the power supply reliability, various methods for completely compensating the current of the single-phase earth fault point are provided at home and abroad. For example: the GFN (ground fault neutralizer) manufactured by Swedishneutral in Sweden is a representative one, and the GFN utilizes an active power supply of power electronics to realize the full compensation of the ground fault, and a method (CN102074950A) for extinguishing and protecting the ground fault of a power distribution network belongs to the active full compensation in technical principle. On the other hand, there are also patents (CN201910992110.3, CN201910992109.0, etc.) for a system and a method for compensating for a ground fault current of a self-generated phase power supply, which have certain advantages in terms of cost and stability because of using a phase power supply converter and no power electronic power supply.
However, regardless of the full compensation technique, the ground fault current compensation system needs to determine the ground fault phase and then perform ground compensation. Once a phase-judging error occurs, the earth fault current compensation system will mistakenly switch into a non-fault phase, resulting in a larger fault current occurring at an earth fault point. The fault current may exceed the current carrying capacity of the lines of the grid system, compromising the safety of the grid system. Therefore, how to suppress the phase fault of the ground fault and the short-circuit current caused by the full compensation device becomes an industry technical problem which needs to be solved urgently at present. However, the prior art does not have a method of suppressing the short-circuit current.
Disclosure of Invention
The application provides a current-limiting protection method and device of a ground fault full compensation system, which aim to solve the problem that once a ground fault phase judgment error occurs in the prior art, a ground fault current compensation system can mistakenly input a non-fault phase, so that a ground fault point generates larger fault current. The fault current may exceed the current carrying capacity of the lines of the power grid system, and endanger the safety of the power grid system.
In a first aspect, the present invention provides a current limiting protection method for a ground fault full compensation system, including:
acquiring a capacitance current Ic of a power grid system;
calculating rated thermal short-circuit current Ibase of the current-limiting reactor according to the capacitance current Ic of the power grid system;
according to the rated thermal short-circuit current IbaseCalculating the current limiting protectionRated continuous current I of reactorE；
According to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL；
According to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system;
wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000021
Figure BDA0002699511420000022
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained.
Further, the current I is according to the rated thermal short circuitbaseCalculating rated continuous current I of the current-limiting protection reactorEThe method comprises the following steps:
according to the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactor by the following formulaE：
Figure BDA0002699511420000023
Wherein k isdThe value range is 5-10 for capacity reduction coefficient.
Further, the current I is according to the rated thermal short circuitbaseCalculating the rated reactance value X of the current-limiting protection reactorLThe method comprises the following steps:
according to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactor by the following formulaL：
Figure BDA0002699511420000024
Wherein the content of the first and second substances,
Figure BDA0002699511420000025
for rated line voltage, X, of the grid systemTAnd the leakage reactance of the earth fault current full compensation system on one side of the neutral point of the power grid system is reduced.
Further, the rated reactance value X according to the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLThe method comprises the following steps:
according to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactor by the following formulaL：
SL＝XLIE 2。
Further, the earth fault current full compensation system comprises a line phase converter 1, a current-limiting protection reactor 2, a split-phase switch group 3, a regulating transformer 4 and a controller 5;
the line phase converter 1 comprises a phase power supply generator 11 and a phase power supply phase compensator 12 which are connected with each other, wherein the phase power supply generator 11 is connected with each phase transmission line in three-phase transmission lines of the power grid system, the phase power supply phase compensator 12 is connected with each phase-splitting switch in three phase-splitting switches contained in the phase-splitting switch group 3, the controller 5 is connected with the regulating transformer 4, the controller 5 is connected with the phase-splitting switch group 3, and the load side of the regulating transformer 4 is connected with a neutral point of the power grid system;
the first end of the current-limiting protection reactor 2 is connected with the power supply side of the regulating transformer 4, the second end of the current-limiting protection reactor 2 is connected with each split-phase switch in three split-phase switches included in the split-phase switch group 3, and the phase power supply phase compensator 12 is grounded; or, the first end of the current-limiting protection reactor 2 is grounded, the second end of the current-limiting protection reactor 2 is connected with the phase power supply phase compensator 12, and the power supply side of the voltage regulating transformer 4 is connected with each of the three split-phase switches included in the split-phase switch group 3.
Further, under the condition that the first end of the current-limiting protection reactor 2 is connected with the power supply side of the regulating transformer 4, and the second end of the current-limiting protection reactor 2 is connected with each split-phase switch of three split-phase switches included in the split-phase switch group 3, the insulation level of the first end of the current-limiting protection reactor 2 and the insulation level of the second end of the current-limiting protection reactor 2 are consistent with the insulation level of the power supply side of the regulating transformer 4.
Further, in a case where the first end of the current-limiting protection reactor 2 is grounded and the second end of the current-limiting protection reactor 2 is connected to the phase compensator 12, the insulation level range of the first end of the current-limiting protection reactor 2 is the insulation level of the power supply side of the voltage-regulating transformer 4
Figure BDA0002699511420000031
And the insulation level of the second end of the current-limiting protection reactor 2 is consistent with the insulation level of the power supply side of the regulating transformer 4.
In a second aspect, the present invention provides a current limiting protection device of a ground fault full compensation system, including:
an acquisition module for acquiring the capacitance current I of the power grid systemc；
A first calculation module for calculating the capacitance current I according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase；
A second calculation module for calculating the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorE；
A third calculation module for calculating the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL；
A fourth calculation module for calculating the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system;
wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000041
Figure BDA0002699511420000042
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained.
According to the technical scheme, the current limiting protection method and device of the ground fault full compensation system provided by the embodiment of the invention can obtain the capacitance current I of the power grid systemc(ii) a According to the capacitance current I of the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase(ii) a According to the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorE(ii) a According to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL(ii) a According to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system; wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000043
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained. Therefore, under the condition that the power grid system has the ground fault and the ground fault current full compensation system judges the ground fault phase wrongly, the ground fault current in the ground fault phase can be limited below a preset threshold value, and the safety of the power grid system is protected.
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In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flow chart of a current limiting protection method of a ground fault full compensation system according to the present invention;
FIG. 2 is a schematic diagram of a ground fault current full compensation system according to the present invention;
FIG. 3 is a second schematic diagram of a ground fault current full compensation system provided by the present invention;
FIG. 4 is a schematic diagram of the present invention providing a method of limiting ground fault current in a ground fault phase;
fig. 5 is a structural diagram of a current limiting protection device of a ground fault full compensation system according to the present invention.
Detailed Description
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following examples do not represent all embodiments consistent with the present application. But merely as exemplifications of systems and methods consistent with certain aspects of the application, as recited in the claims.
Referring to fig. 1, fig. 1 is a flowchart of a current limiting protection method of a ground fault full compensation system according to the present invention. As shown in fig. 1, the method comprises the following steps:
step 101, obtaining a capacitance current I of a power grid systemc。
In step 101, a capacitance current I of the grid system may be obtainedc。
102, according to the capacitance current I of the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase。
In step 102, the capacitance current I of the grid system may be determinedcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase。
103, according to the rated thermal short-circuit current IbaseComputing stationRated continuous current I of the current-limiting protection reactorE。
In step 103, the thermal short-circuit current I may be determined according to the rated thermal short-circuit current IbaseCalculating the rated continuous current I of the current-limiting protection reactorE。
Optionally, said current is dependent on said rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorEThe method comprises the following steps:
according to the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactor by the following formulaE：
Figure BDA0002699511420000051
Wherein k isdThe value range is 5-10 for capacity reduction coefficient.
It should be noted that the rated continuous current I of the current-limiting protection reactor can be calculated by the following formulaE：
Figure BDA0002699511420000052
Wherein k isdIn order to reduce the capacity coefficient, the value range can be 5-10.
104, according to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL。
In step 104, the thermal short circuit current I may be rated according tobaseCalculating the rated reactance value X of the current-limiting protection reactorL。
Optionally, said current is dependent on said rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorLThe method comprises the following steps:
according to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactor by the following formulaL：
Figure BDA0002699511420000061
Wherein the content of the first and second substances,
Figure BDA0002699511420000062
for rated line voltage, X, of the grid systemTAnd the leakage reactance of the earth fault current full compensation system on one side of the neutral point of the power grid system is reduced.
It should be noted that the rated reactance value X of the current-limiting protection reactor can be calculated by the following formulaL：
Figure BDA0002699511420000063
Wherein the content of the first and second substances,
Figure BDA0002699511420000067
rated line voltage, X, for the grid systemTAnd the leakage reactance of the earth fault current full compensation system on the neutral point side of the power grid system is reduced.
105, according to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system; wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000064
Figure BDA0002699511420000065
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained.
In step 105, the reactance value X may be determined according to the rated reactance value of the current-limiting protection reactorLAnd rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has ground fault and the ground fault current full compensation system judges the ground fault phase wrongly, the current limiting reactor limits the ground fault current in the ground fault phase below a preset threshold value. The preset threshold value is the maximum current value which can be borne by the power grid system.
Wherein, the capacitance current I can be determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000066
Figure BDA0002699511420000071
k is a current limiting coefficient and ranges from 2 to 6, kTThe rated transformation ratio of the regulating transformer in the system is fully compensated for the earth fault current.
It should be noted that, in the prior art, once a ground fault phase determination error occurs, the ground fault current compensation system may mistakenly switch into a non-fault phase, resulting in a larger fault current occurring at a ground fault point. The fault current may exceed the current carrying capacity of the lines of the grid system, compromising the safety of the grid system.
In the invention, when the power grid system has ground fault and the ground fault current full compensation system judges the ground fault phase wrongly, the ground fault current in the ground fault phase can be limited below a preset threshold value, so that the safety of the power grid system is protected.
Optionally, the current-limiting protection reactor is based on a rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLThe method comprises the following steps:
according to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactor by the following formulaL：
SL＝XLIE 2。
It should be noted that the rated capacity S of the current-limiting protection reactor can be calculated by the following formulaL：
SL＝XLIE 2。
For example, the rated line voltage of the grid system
Figure BDA0002699511420000072
10kV, the capacitance current of the power grid system is 100A, the current limiting coefficient k is 4, and the rated transformation ratio k of the regulating transformerTTo 1/15, the rated thermal short-circuit current I of the current-limiting protection reactor is calculatedbaseIs 6 kA;
taking a volume reduction coefficient kdTo 5, calculating rated continuous current I of the current-limiting protection reactorEIs 1.2 kA;
leakage reactance X reduced to neutral point side of power grid system by earth fault current full compensation systemTThe rated reactance value X of the current-limiting protection reactor is calculated to be 14.4 ohmsL0.047 ohm;
finally, calculating the rated capacity S of the current-limiting protection reactorLIs 68 kVA.
Optionally, the ground fault current full compensation system includes a line-to-phase converter 1, a current-limiting protection reactor 2, a split-phase switch group 3, a regulating transformer 4 and a controller 5;
the line phase converter 1 comprises a phase power supply generator 11 and a phase power supply phase compensator 12 which are connected with each other, wherein the phase power supply generator 11 is connected with each phase transmission line in three-phase transmission lines of the power grid system, the phase power supply phase compensator 12 is connected with each phase-splitting switch in three phase-splitting switches contained in the phase-splitting switch group 3, the controller 5 is connected with the regulating transformer 4, the controller 5 is connected with the phase-splitting switch group 3, and the load side of the regulating transformer 4 is connected with a neutral point of the power grid system;
the first end of the current-limiting protection reactor 2 is connected with the power supply side of the regulating transformer 4, the second end of the current-limiting protection reactor 2 is connected with each split-phase switch in three split-phase switches included in the split-phase switch group 3, and the phase power supply phase compensator 12 is grounded; or, the first end of the current-limiting protection reactor 2 is grounded, the second end of the current-limiting protection reactor 2 is connected with the phase power supply phase compensator 12, and the power supply side of the voltage regulating transformer 4 is connected with each of the three split-phase switches included in the split-phase switch group 3.
Fig. 2 is a schematic diagram of a ground fault current full compensation system according to the present invention; fig. 3 is a second schematic diagram of the ground fault current full compensation system provided by the present invention.
The earth fault current full compensation system can comprise a line phase converter 1, a current limiting protection reactor 2, a split-phase switch group 3, a regulating transformer 4 and a controller 5.
The line-phase converter 1 may include a phase power generator 11 and a phase power phase compensator 12 connected to each other. A phase supply generator 11 is connected to each of the three phase transmission lines of the grid system, and a phase supply phase compensator 12 is connected to each of the three phase splitting switches included in the phase splitting switch group 3. The controller 5 can be connected with the regulating transformer 4, and the controller 5 can also be connected with the split-phase switch group 3. The load side of the regulating transformer 4 can be connected to the neutral point N of the grid system.
As shown in fig. 2, a first end of the current-limiting protection reactor 2 may be connected to the power supply side of the regulating transformer 4, and a second end of the current-limiting protection reactor 2 may be connected to each of the three split phase switches included in the split phase switch bank 3, and the phase power supply phase compensator 12 may be grounded.
Alternatively, as shown in fig. 3, the first end of the current-limiting protection reactor 2 is grounded, the second end of the current-limiting protection reactor 2 is connected to the phase compensator 12 of the phase power supply, and the power supply side of the regulating transformer 4 may be connected to each of the three split phase switches included in the split phase switch group 3.
The grid system may comprise an ac power source 6, a transformer 7, a coil 8 and a three-phase power line A, B, C.
Optionally, under the condition that the first end of the current-limiting protection reactor 2 is connected to the power supply side of the voltage regulating transformer 4, and the second end of the current-limiting protection reactor 2 is connected to each split-phase switch of three split-phase switches included in the split-phase switch group 3, the insulation level of the first end of the current-limiting protection reactor 2 and the insulation level of the second end of the current-limiting protection reactor 2 are consistent with the insulation level of the power supply side of the voltage regulating transformer 4.
Further, in the case where the first end of the current-limiting protection reactor 2 is connected to the power supply side of the regulating transformer 4, and the second end of the current-limiting protection reactor 2 is connected to each of the three split-phase switches included in the split-phase switch group 3, the insulation level of the first end of the current-limiting protection reactor 2 and the insulation level of the second end of the current-limiting protection reactor 2 may be made to coincide with the insulation level of the power supply side of the regulating transformer 4.
Optionally, under the condition that the first end of the current-limiting protection reactor 2 is grounded, and the second end of the current-limiting protection reactor 2 is connected to the phase compensator 12 of the phase power supply, the insulation level range of the first end of the current-limiting protection reactor 2 is the insulation level of the power side of the voltage regulating transformer 4
Figure BDA0002699511420000081
And the insulation level of the second end of the current-limiting protection reactor 2 is consistent with the insulation level of the power supply side of the regulating transformer 4.
Further, in the case where the first end of the current-limiting protection reactor 2 is grounded and the second end of the current-limiting protection reactor 2 is connected to the phase compensator 12 of the phase power supply source, the range of the insulation level of the first end of the current-limiting protection reactor 2 may be the insulation level of the power source side of the voltage-regulating transformer 4
Figure BDA0002699511420000091
The insulation level of the second end of the current limiting protection reactor 2 may coincide with the insulation level of the power supply side of the regulating transformer 4.
Fig. 4 is a schematic diagram illustrating a method for limiting a ground fault current in a ground fault phase according to the present invention. As shown in fig. 4, the grid system may include at least two lines, i.e., a first line, a second line, an nth line, and so on. The zero sequence current of the first line is I01(ii) a Zero sequence current of the second line is I02(ii) a Zero sequence current of Nth line is I0n. The zero sequence current of each line comprises three-phase current, namely A-phase current, B-phase current and C-phase current. Under the condition that the C phase of the Nth line of the at least two lines has single-phase earth fault, the current can be limited by the current-limiting protection reactor to avoid harming the safety of a power grid system.
Furthermore, each line protection device of the power grid system can be provided with zero-sequence current protection, and the zero-sequence current protection fixed value can be calculated according to the following formula:
Ith＝kthIc
wherein, IthSetting a zero sequence current protection constant value; k is a radical ofthThe value range is 1-2 for sensitivity coefficient; i iscIs the capacitance current of the power grid system.
When the earth fault current exceeds the zero sequence current protection constant value of the line protection device, the fault line can be tripped through the line protection device to realize fault isolation.
According to the technical scheme, the current limiting protection method of the ground fault full compensation system provided by the embodiment of the invention obtains the capacitance current I of the power grid systemc(ii) a According to the capacitance current I of the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase(ii) a According to the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorE(ii) a According to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL(ii) a According to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system; wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000092
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained. Therefore, under the condition that the power grid system has the ground fault and the ground fault current full compensation system judges the ground fault phase wrongly, the ground fault current in the ground fault phase can be limited below a preset threshold value, and the safety of the power grid system is protected.
Referring to fig. 5, fig. 5 is a structural diagram of a current limiting protection device of a ground fault full compensation system according to the present invention. As shown in fig. 5, the current limiting protection device 500 of the ground fault full compensation system includes an obtaining module 501, a first calculating module 502, a second calculating module 503, a third calculating module 504, and a fourth calculating module 505, wherein:
an obtaining module 501, configured to obtain a capacitance current I of a power grid systemc；
A first calculation module 502, configured to calculate a capacitance current I according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase；
A second calculation module 503 for calculating the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorE；
A third calculation module 504 for calculating a thermal short-circuit current I according to said ratingbaseCalculating the rated reactance value X of the current-limiting protection reactorL；
A fourth calculating module 505, configured to calculate a rated reactance value X according to the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system;
wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure BDA0002699511420000101
Figure BDA0002699511420000102
k is a current limiting coefficientThe value range is 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained.
The current limiting protection device 500 of the ground fault full compensation system can implement each process implemented by the current limiting protection device of the ground fault full compensation system in the method embodiment of fig. 1, and is not described herein again to avoid repetition. And the current-limiting protection device 500 of the ground fault full compensation system can limit the ground fault current in the ground fault phase to be below a preset threshold value and protect the safety of the power grid system under the condition that the power grid system has a ground fault and the ground fault current full compensation system has a wrong judgment on the ground fault phase.
The embodiments provided in the present application are only a few examples of the general concept of the present application, and do not limit the scope of the present application. Any other embodiments extended according to the scheme of the present application without inventive efforts will be within the scope of protection of the present application for a person skilled in the art.

Claims (8)

1. A current limiting protection method of a ground fault full compensation system is characterized by comprising the following steps:
obtaining capacitance current I of power grid systemc；
According to the capacitance current I of the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase；
According to the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorE；
According to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL；
According to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation systemIs XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system;
wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure FDA0002699511410000011
Figure FDA0002699511410000012
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained.
2. Method according to claim 1, characterized in that said thermal short-circuit current I is dependent on said nominal valuebaseCalculating rated continuous current I of the current-limiting protection reactorEThe method comprises the following steps:
according to the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactor by the following formulaE：
Figure FDA0002699511410000013
Wherein k isdThe value range is 5-10 for capacity reduction coefficient.
3. The method of claim 2, wherein said short circuiting is based on said nominal thermalCurrent IbaseCalculating the rated reactance value X of the current-limiting protection reactorLThe method comprises the following steps:
according to the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactor by the following formulaL：
Figure FDA0002699511410000014
Wherein the content of the first and second substances,
Figure FDA0002699511410000015
for rated line voltage, X, of the grid systemTAnd the leakage reactance of the earth fault current full compensation system on one side of the neutral point of the power grid system is reduced.
4. The method of claim 3, wherein the current-limiting protection reactor is configured to have a reactance value X according to a rated reactance value of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLThe method comprises the following steps:
according to the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactor by the following formulaL：
SL＝XLIE 2。
5. The method according to any one of claims 1 to 4, wherein the earth fault current full compensation system comprises a line phase converter 1, a current limiting protection reactor 2, a split phase switch group 3, a regulating transformer 4 and a controller 5;
the line phase converter 1 comprises a phase power supply generator 11 and a phase power supply phase compensator 12 which are connected with each other, wherein the phase power supply generator 11 is connected with each phase transmission line in three-phase transmission lines of the power grid system, the phase power supply phase compensator 12 is connected with each phase-splitting switch in three phase-splitting switches contained in the phase-splitting switch group 3, the controller 5 is connected with the regulating transformer 4, the controller 5 is connected with the phase-splitting switch group 3, and the load side of the regulating transformer 4 is connected with a neutral point of the power grid system;
the first end of the current-limiting protection reactor 2 is connected with the power supply side of the regulating transformer 4, the second end of the current-limiting protection reactor 2 is connected with each split-phase switch in three split-phase switches included in the split-phase switch group 3, and the phase power supply phase compensator 12 is grounded; or, the first end of the current-limiting protection reactor 2 is grounded, the second end of the current-limiting protection reactor 2 is connected with the phase power supply phase compensator 12, and the power supply side of the voltage regulating transformer 4 is connected with each of the three split-phase switches included in the split-phase switch group 3.
6. The method according to claim 5, characterized in that in a case where a first end of the current-limiting protection reactor 2 is connected to the power supply side of the regulating transformer 4 and a second end of the current-limiting protection reactor 2 is connected to each of three split phase switches included in the split phase switch group 3, the insulation level of the first end of the current-limiting protection reactor 2 and the insulation level of the second end of the current-limiting protection reactor 2 coincide with the insulation level of the power supply side of the regulating transformer 4.
7. The method according to claim 5, characterized in that in the case where the first end of the current-limiting protection reactor 2 is grounded and the second end of the current-limiting protection reactor 2 is connected to the phase power supply phase compensator 12, the range of the insulation level of the first end of the current-limiting protection reactor 2 is the range of the insulation level of the power supply side of the regulating transformer 4
Figure FDA0002699511410000021
And the insulation level of the second end of the current-limiting protection reactor 2 is consistent with the insulation level of the power supply side of the regulating transformer 4.
8. A current limiting protection device for a ground fault full compensation system, comprising:
an acquisition module for acquiring the capacitance current I of the power grid systemc；
A first calculation module for calculating the capacitance current I according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactorbase；
A second calculation module for calculating the rated thermal short-circuit current IbaseCalculating rated continuous current I of the current-limiting protection reactorE；
A third calculation module for calculating the rated thermal short-circuit current IbaseCalculating the rated reactance value X of the current-limiting protection reactorL；
A fourth calculation module for calculating the rated reactance value X of the current-limiting protection reactorLAnd the rated continuous current IECalculating the rated capacity S of the current-limiting protection reactorLSo that the rated reactance value contained in the earth fault current full compensation system is XLRated capacity of SLWhen the power grid system has a ground fault and the ground fault current full compensation system judges the ground fault phase incorrectly, limiting the ground fault current in the ground fault phase to be below a preset threshold value, wherein the preset threshold value is the maximum current value which can be borne by the power grid system;
wherein the capacitance current I is determined according to the power grid systemcCalculating the rated thermal short-circuit current I of the current-limiting reactor according to the following formulabase：
Figure FDA0002699511410000022
Figure FDA0002699511410000023
k is a current limiting coefficient and ranges from 2 to 6, kTAnd the rated transformation ratio of the voltage regulating transformer in the earth fault current full compensation system is obtained.
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