Disclosure of Invention
In order to solve the problem that the action time limit of a section III of the variable time limit distance protection of a power flow receiving end is too long in the case of a large-resistance single-phase earth fault in the background art, the invention provides a voltage acceleration method for the variable time limit distance protection of a power grid line, which comprises the following steps:
collecting instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position, and determining a voltage fundamental wave phasor value according to the instantaneous values of the secondary values of the three-phase voltage
Determining the current fundamental wave phasor value according to the instantaneous value of the secondary value of the three-phase current
And setting the fault phase voltage fundamental phasor as
A voltage fundamental phasor value having a value equal to the faulted phase;
protection of voltage fundamental phasor values at installation site according to failed phase and variable time-limited distance
Calculating positive sequence voltage phasor
Protecting the current fundamental wave phasor value at the installation site according to the variable time-limit distance
Calculating zero sequence current
And, protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limited distance
Calculating the positive sequence current phasor
When according to the zero sequence current
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Δ t before start-up of the method
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
III。
Further, the fundamental wave phasor value of the voltage at the installation position is protected according to the faulted phase and the variable time-limit distance
Calculating positive sequence voltage phasor
The method comprises the following steps:
when the failed phase is A, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
when the failed phase is B phase, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
positive sequence voltage phasor when C phase is failed
The calculation formula of (2) is as follows:
further, protecting the current fundamental wave phasor value at the installation position according to the variable time limit distance
Calculating zero sequence current
And protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limit distance
Calculating the positive sequence current phasor
The method comprises the following steps: :
zero sequence current
The calculation formula of (2) is as follows:
when the fault is A phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
when the fault is B phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
positive sequence current phasor when C-phase is failed
The calculation formula of (2) is as follows:
further, the current according to the zero sequence current
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Δ t before start-up of the method
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe method comprises the following steps:
according to zero sequence current
And positive sequence current phasor
Establishing a power flow direction criterion, wherein the formula of the power flow direction criterion is as follows:
wherein, F is1The range of F is less than or equal to minus 60 degrees1≤60°;
According to zero sequence current
And positive sequence voltage phasor
Establishing fault transition resistance criterion F
2The formula is as follows:
wherein, F is
2In the range of-D.ltoreq.F
2D is less than or equal to D, when C is
LWhen the ratio is larger than m, the ratio is,
when C is present
LWhen the thickness is less than or equal to m,
n is the set resistivity, C
LThe length of the actual power grid line is m, and the length value of the set power grid line is m;
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is not more than 60 degrees
1Less than or equal to 60 degrees and determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2When D is less than or equal to D, according to fault phase voltage fundamental wave phasor
Δ t before start-up of the method
1Time fault phase voltage fundamental phasor
Andset margin factor K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe formula of (1) is:
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is more than or equal to 60 degrees
1Less than or equal to 60 degrees, or zero sequence current determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2And when the voltage is less than or equal to D, ending the voltage acceleration method.
According to another aspect of the present invention, there is provided a voltage step-up device for variable time-limited distance protection of a power grid line, the device comprising:
the data acquisition unit is used for acquiring instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position and determining a voltage fundamental wave phasor value according to the instantaneous values of the secondary values of the three-phase voltage
Determining the current fundamental wave phasor value according to the instantaneous value of the secondary value of the three-phase current
And setting the fault phase voltage fundamental phasor as
A voltage fundamental phasor value having a value equal to the faulted phase;
a first calculation unit for protecting the phasor value of the voltage fundamental wave at the installation site according to the failed phase and the variable time-limit distance
Calculating positive sequence voltage phasor
A second calculation unit for protecting the phasor value of the current fundamental wave at the installation site according to the variable time-limited distance
Calculating zero sequence current
And protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limit distance
Calculating the positive sequence current phasor
A third calculation unit for calculating a third zero sequence current according to the first zero sequence current
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Before the device starts Δ t
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
III。
Further, the apparatus further comprises a parameter setting unit for setting a margin coefficient K1And the action time limit t of the original distance protection III sectionIIIResistance coefficient N, length C of actual grid lineLAnd a set line length value m.
Further, the first calculation unit protects the phasor value of the voltage fundamental wave at the installation site according to the failed phase and the variable time-limit distance
Calculating positive sequence voltage phasor
The method comprises the following steps:
when the failed phase is A, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
when the failed phase is B phase, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
positive sequence voltage phasor when C phase is failed
The calculation formula of (2) is as follows:
further, the second calculating unit protects the phasor value of the current fundamental wave at the installation position according to the variable time limit distance
Calculating zero sequence current
And protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limit distance
Calculating the positive sequence current phasor
The method comprises the following steps: :
zero sequence current
The calculation formula of (2) is as follows:
when the fault is A phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
when the fault is B phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
positive sequence current phasor when C-phase is failed
The calculation formula of (2) is as follows:
further, the third calculation unit is used for calculating the zero sequence current according to the zero sequence current
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the phase power of the faultFundamental phasor of voltage
Before the device starts Δ t
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe method comprises the following steps:
according to zero sequence current
And positive sequence current phasor
Establishing a power flow direction criterion, wherein the formula of the power flow direction criterion is as follows:
wherein, F is1The range of F is less than or equal to minus 60 degrees1≤60°;
According to zero sequence current
And positive sequence voltage phasor
Establishing fault transition resistance criterion F
2The formula is as follows:
wherein, F is
2In the range of-D.ltoreq.F
2D is less than or equal to D, when C is
LWhen the ratio is larger than m, the ratio is,
when C is present
LWhen the thickness is less than or equal to m,
n is a set resistance coefficient, and m is a set line length value;
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is not more than 60 degrees
1Less than or equal to 60 degrees and determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2When D is less than or equal to D, according to fault phase voltage fundamental wave phasor
Before the device starts Δ t
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe formula of (1) is:
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is more than or equal to 60 degrees
1Less than or equal to 60 degrees, or zero sequence current determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2And when the voltage is less than or equal to D, the voltage accelerating device finishes the operation.
The voltage acceleration method and the voltage acceleration device for time-limit-variable distance protection of the power grid line, provided by the technical scheme of the invention, judge whether the action time limit of the distance protection III section needs to be adjusted or not through the established tide direction criterion and the fault transition resistance criterion, and correct the action time limit of the distance protection III section through a set calculation formula when the criterion confirms that the action time limit of the distance protection III section needs to be adjusted. The method and the device can obviously shorten the action time limit of the distance protection III section for the variable time limit distance protection installed at the tidal current receiving end of the power grid line when the line has a large-resistance single-phase earth fault and only the action of the distance protection III section is carried out.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flow chart of a voltage acceleration method for variable time-limited distance protection of a grid line according to a preferred embodiment of the present invention. The voltage acceleration method 100 for variable time-limited distance protection of a grid line according to the preferred embodiment as shown in fig. 1 starts with step 101.
In
step 101, instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation position are collected, and voltage fundamental wave phasor values are determined according to the instantaneous values of the secondary values of the three-phase voltage
Determining the current fundamental wave phasor value according to the instantaneous value of the secondary value of the three-phase current
And setting the fault phase voltage fundamental phasor as
A voltage fundamental phasor value having a value equal to the faulted phase;
at
step 102, the phasor value of the fundamental wave of the voltage at the installation is protected according to the faulted phase and the variable time-limited distance
Calculating positive sequence voltage phasor
At
step 103, the current fundamental phasor value at the installation site is protected according to the variable time-limit distance
Calculating zero sequence current
And protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limit distance
Calculating the positive sequence current phasor
In
step 104, when the zero sequence current is based on
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Δ t before start-up of the method
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
III。
Preferably, the fundamental wave phasor value of the voltage at the installation is protected according to the faulted phase and the variable time-limited distance
Calculating positive sequence voltage phasor
The formula of (1) is as follows:
when the failed phase is A, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
when the failed phase is B phase, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
positive sequence voltage phasor when C phase is failed
The calculation formula of (2) is as follows:
preferably, said time-dependent distance protectionCurrent fundamental phasor value at protected installation
Calculating zero sequence current
And protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limit distance
Calculating the positive sequence current phasor
The method comprises the following steps: :
zero sequence current
The calculation formula of (2) is as follows:
when the fault is A phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
when the fault is B phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
positive sequence current phasor when C-phase is failed
The calculation formula of (2) is as follows:
preferably, said zero sequence current is used as said reference
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Δ t before start-up of the method
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe method comprises the following steps:
according to zero sequence current
And positive sequence current phasor
Establishing a power flow direction criterion,the formula of the trend direction criterion is as follows:
wherein, F is1The range of F is less than or equal to minus 60 degrees1≤60°;
According to zero sequence current
And positive sequence voltage phasor
Establishing fault transition resistance criterion F
2The formula is as follows:
wherein, F is
2In the range of-D.ltoreq.F
2D is less than or equal to D, when C is
LWhen the ratio is larger than m, the ratio is,
when C is present
LWhen the thickness is less than or equal to m,
n is the set resistivity, C
LThe length of the actual power grid line is the length of the actual power grid line, and m is the set length value of the power grid line;
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is not more than 60 degrees
1Less than or equal to 60 degrees and determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2When D is less than or equal to D, according to fault phase voltage fundamental wave phasor
Δ t before start-up of the method
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe formula of (1) is:
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is more than or equal to 60 degrees
1Less than or equal to 60 degrees, or zero sequence current determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2And when the voltage is less than or equal to D, ending the voltage acceleration method.
Fig. 2 is a schematic structural diagram of a voltage accelerating device for time-limited distance protection of a power grid line according to a preferred embodiment of the invention. As shown in fig. 2, the voltage accelerating device 200 for variable time-limit distance protection of the grid line according to the preferred embodiment includes:
a parameter setting unit 201 for setting a margin coefficient K1And the action time limit t of the original distance protection III sectionIIIResistance coefficient N, length C of actual grid lineLAnd a grid line length value m.
A
data acquisition unit 202 for acquiring instantaneous values of secondary values of three-phase voltage and current at a variable time-limit distance protection installation site, and determining a voltage fundamental wave phasor value according to the instantaneous values of the secondary values of the three-phase voltage
Determining the current fundamental wave phasor value according to the instantaneous value of the secondary value of the three-phase current
And setting the fault phase voltage fundamental phasor as
A voltage fundamental phasor value having a value equal to the faulted phase;
a
first calculation unit 203 for protecting the phasor value of the fundamental wave of the voltage at the installation site according to the faulted phase and the variable time-limited distance
Calculating positive sequence voltage phasor
A
second calculation unit 204 for protecting the current fundamental phasor value at the installation according to a variable time-limited distance
Calculating zero sequence current
And, protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limited distance
Positive sequence current phasor
A
third calculation unit 205 for calculating a current according to the zero sequence current
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Before the device starts Δ t
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
III。
Preferably, the
first calculation unit 203 protects the phasor value of the voltage fundamental wave at the installation according to the failed phase and the variable time-limit distance
Calculating positive sequence voltage phasor
The method comprises the following steps:
when the fault is A phase, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
when the failed phase is B phase, the positive sequence voltage phasor
The calculation formula of (2) is as follows:
positive sequence voltage phasor when C phase is failed
The calculation formula of (2) is as follows:
preferably, the
second calculation unit 204 protects the phasor value of the current fundamental wave at the installation according to the variable time-limited distance
Calculating zero sequence current
And protecting the current fundamental phasor value at the installation site according to the faulted phase and the variable time-limit distance
Calculating the positive sequence current phasor
The formula including the sum positive sequence current phasor is:
zero sequence current
The calculation formula of (2) is as follows:
when the fault is A phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
when the fault is B phase, the positive sequence current phasor
The calculation formula of (2) is as follows:
positive sequence current phasor when C-phase is failed
The calculation formula of (2) is as follows:
preferably, the
third calculation unit 205 calculates the zero sequence current according to the zero sequence current
And positive sequence current phasor
The determined value does not satisfy the established flow direction criterion F
1And according to the zero sequence current
And positive sequence voltage phasor
The determined value satisfies the established fault transition resistance criterion F
2According to the fault phase voltage fundamental wave phasor
Before the device starts Δ t
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe method comprises the following steps:
according to zero sequence current
And positive sequence current phasor
Establishing a power flow direction criterion, wherein the formula of the power flow direction criterion is as follows:
wherein, F is1The range of F is less than or equal to minus 60 degrees1≤60°;
According to zero sequence current
And positive sequence voltage phasor
Establishing fault transition resistance criterion F
2The formula is as follows:
wherein, F is
2In the range of-D.ltoreq.F
2D is less than or equal to D, when C is
LWhen the ratio is larger than m, the ratio is,
when C is present
LWhen the thickness is less than or equal to m,
n is a set resistance coefficient, and m is a set line length value;
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is not more than 60 degrees
1Less than or equal to 60 degrees and determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2When D is less than or equal to D, according to fault phase voltage fundamental wave phasor
Before the device starts Δ t
1Time fault phase voltage fundamental phasor
And a set margin coefficient K
1And the action time limit t of the original distance protection III section
IIICalculating the corrected distance protection III section operation time t'
IIIThe formula of (1) is:
when determined according to the calculation
And positive sequence current phasor
Obtained F
1The value of F is more than or equal to 60 degrees
1Less than or equal to 60 degrees, or zero sequence current determined according to calculation
And positive sequence voltage phasor
Obtained F
2Has a value of-D. ltoreq. F
2And when the voltage is less than or equal to D, the voltage accelerating device finishes the operation.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.