CN109738758B - Distribution network line fault type judgment method based on voltage characteristics - Google Patents
Distribution network line fault type judgment method based on voltage characteristics Download PDFInfo
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Abstract
The invention relates to a distribution network line fault type judgment method based on voltage characteristics, and belongs to the field of power grids. The method comprises the following steps: and judging the fault phase and the grounding conditions of the power supply side and the load side according to the phase, amplitude and voltage relations of the power supply side and the load side. The conventional method collects current, the current is small when the fault occurs, the precise action cannot be realized, and if an amplifier is adopted, the fault is easily judged by mistake when the load and the like are slightly changed. The invention utilizes the advantages that the voltage phase and amplitude change is large during various faults, the difference between the power supply side and the load side is large, the mutual comparison is facilitated, and the fault type is judged through the voltage characteristic.
Description
Technical Field
The invention belongs to the field of power grids, and relates to a distribution network line fault type judgment method based on voltage characteristics.
Background
Due to the construction height of the 10kV distribution network overhead line, the line is easy to break due to external force damage, or other foreign objects are lapped on the line to conduct electricity, so that people and animals get electric shock.
Due to the continuous development of the communication technology, mature application of the terminal data acquisition and interactive analysis application technology can compare and analyze the line fault type through the phase and amplitude relation of the end voltage and the tail voltage of the line, and provide technical support for fault processing.
Disclosure of Invention
In view of this, the present invention provides a method for determining a fault type of a distribution network line based on voltage characteristics.
In order to achieve the purpose, the invention provides the following technical scheme:
a distribution network line fault type judgment method based on voltage characteristics is as follows: and judging the fault phase and the grounding conditions of the power supply side and the load side according to the phase, amplitude and voltage relations of the power supply side and the load side.
Further, the method specifically comprises the following steps:
suppose a phase a failure:
(1) when the two sides of the circuit are disconnected and not grounded, the phase and amplitude of the voltage on the power supply side are unchanged, the voltage on the load side is reduced, the phase is opposite to the phase before the fault, and the disconnection and non-ground fault of the circuit is judged;
(2) when the load side is not grounded, the voltage fault phase of the power side is 0, the amplitude of the other two phase voltages is 1.732 times of the original value, the phase deviation is 30 degrees, the zero sequence voltage is opposite to the original A phase voltage in phase and has the same amplitude, the load side broken line phase voltage is smaller, the phase is opposite to the phase before the fault, and the broken line power side is grounded and the load side is not grounded;
(3) when the power supply side is not grounded after disconnection and the load side is grounded: the phase of the voltage at the power supply side is shifted, the amplitude is increased, the shifting angle and the amplitude increasing amplitude are related to the impedance of the transformer winding at the load side, and the fault phase voltage at the load side is 0;
(4) when the two sides are grounded in a broken line mode or in a single-phase ground mode without breaking the line: the fault phase voltage of the power supply side and the fault phase voltage of the load side are 0, the phase of the other phase voltages are shifted by 30 degrees, and the amplitude is 1.732 times of the original amplitude.
Further, the method specifically comprises the following steps:
assume a phase C fault:
(1) c phase disconnection, no ground at power supply side and ground at load side
A power supply side:
the power side voltage acquisition terminal acquires power side phase and amplitude, the three-phase voltage is symmetrical three-phase voltage, and the phase and amplitude relation is as follows:
and (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
Uc＝0
zero-sequence component:
positive sequence component:
negative sequence component:
wherein:
is the voltage of the A-phase,
is the phase voltage of the B phase,
is C phase voltage, U is standard voltage amplitude,
is zero-sequence voltage when the phase C fails,
is the positive sequence voltage when the C phase fails,
negative sequence voltage when C phase fault occurs;
judging that the C phase is disconnected, the power supply side is not grounded, and the load side is grounded by comparing the voltage relationship between the power supply side and the load side;
(2) c phase disconnection, no ground on power supply side and no ground on load side
A power supply side:
the power side voltage acquisition terminal acquires power side phase and amplitude, the three-phase voltage is symmetrical three-phase voltage, and the phase and amplitude relation is as follows:
and (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
judging that the C phase is disconnected and the power supply side and the load side are not grounded by comparing the voltage relation of the power supply side and the load side;
(3) c phase disconnection, power source side grounding, load side non-grounding
A power supply side:
the power supply side voltage acquisition terminal acquires the phase and the amplitude of the power supply side, and the phase and the amplitude are in the following relation because the grounding phase C of the power supply side is zero, the three-phase voltage is asymmetric three-phase voltage and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
and (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
judging that the C phase is disconnected and the power supply side and the load side are not grounded by comparing the voltage relation of the power supply side and the load side;
(4) c phase disconnection, power source side grounding and load side grounding
The power supply side is the same as the load side:
the power supply side voltage acquisition terminal acquires power supply side phase and amplitude, and the three-phase voltage is asymmetric three-phase voltage and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method because the grounding C phase is zero, and the phase and amplitude relations are as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
and comparing the voltage relationship between the power supply side and the load side to judge that the C phase source side and the load side are grounded.
The invention has the beneficial effects that: the conventional method collects current, the current is small when the fault occurs, the precise action cannot be realized, and if an amplifier is adopted, the fault is easily judged by mistake when the load and the like are slightly changed. The invention utilizes the advantages that the voltage phase and amplitude change is large during various faults, the difference between the power supply side and the load side is large, the mutual comparison is facilitated, and the fault type is judged through the voltage characteristic.
Drawings
In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:
FIG. 1 is a phase relationship when the two sides of the A-phase fault are disconnected and not grounded;
FIG. 2 shows the phase relationship between the power source side grounded and the load side ungrounded after the A-phase fault is disconnected;
FIG. 3 is a phase relationship between the power source side without the ground and the load side with the ground after the A-phase fault is disconnected;
FIG. 4 shows the phase relationship between the phase A fault and the phase A fault, wherein the phase A fault has two sides connected to the ground in a broken line or connected to the ground in a single phase;
FIG. 5 is a schematic diagram of a phase C fault;
FIG. 6 is a vector diagram of the power source side of the C-phase disconnection, the power source side of which is not grounded, and the load side of which is grounded;
FIG. 7 is a graph showing the magnitude of the load side direction of the C-phase disconnection, the power supply side not being grounded, and the load side being grounded;
FIG. 8 is a vector diagram of the power supply side with the power supply side not grounded and the load side not grounded, for the phase C disconnection;
FIG. 9 is a side-view of the load with the power supply side not grounded and the load side not grounded;
FIG. 10 is a vector diagram of phase C open line, power supply side grounded, load side ungrounded;
FIG. 11 is a side view of a load with the power supply side grounded and the load side ungrounded, with the C-phase disconnected;
fig. 12 is a graph of the magnitude of the phase C disconnection, the power source side grounded, the load side grounded, and the load side.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Taking the phase a fault as an example:
(1) when the two sides are disconnected and not grounded: the phase and amplitude of the voltage at the power supply side are unchanged, the phase voltage of the broken line at the load side is reduced, the phase is opposite to the phase before the fault, the broken line and ungrounded fault of the line can be judged, and the phase relation is shown in figure 1.
(2) After disconnection, the power supply side is grounded, and the load side is not grounded: the fault phase of the power supply side voltage is 0, the amplitude of the other two phase voltages is 1.732 times of the original value, the phase shifts by 30 degrees, the zero sequence voltage is opposite to the phase of the original A phase voltage in phase, and the amplitude is the same, as shown in fig. 2Ua ', Ub', U0, the load side broken line phase voltage is smaller and the phase is opposite to the phase before the fault, the broken line power supply side is grounded, the load side is not grounded, and the phase relation is shown in fig. 2.
(3) After disconnection, the power supply side is not grounded, and the load side is grounded: the phase of the voltage at the power supply side is shifted, the amplitude is increased, the shifting angle and the amplitude increasing amplitude are related to the impedance of the transformer winding at the load side, and the fault phase voltage at the load side is 0; the phase relationship is shown in figure 3.
(4) Two sides are grounded in a broken line mode or in a single-phase mode without breaking the line: the fault phase voltage of the power supply side and the fault phase voltage of the load side are 0, the phase of the other phase voltages is shifted by 30 degrees, the amplitude is 1.732 times of the original amplitude, and the phase relation is shown in figure 4.
Taking the C-phase fault as an example, the C-phase line in the line shown in fig. 5 is broken:
1. c phase disconnection, no ground at power supply side and ground at load side
A power supply side:
the power side voltage acquisition terminal acquires power side phase and amplitude, the three-phase voltage is symmetrical three-phase voltage, and the phase and amplitude relation is as follows:
And (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
wherein:
is the voltage of the A-phase,
is the phase voltage of the B phase,
is C phase voltage, U is standard voltage amplitude,
is zero-sequence voltage when the phase C fails,
is the positive sequence voltage when the C phase fails,
is the negative sequence voltage when the C phase fails. The decomposed vector graph is shown in fig. 7.
The C-phase disconnection can be judged by comparing the voltage relationship between the power supply side and the load side, the power supply side is not grounded, and the load side is grounded.
2. C phase disconnection, no ground on power supply side and no ground on load side
A power supply side:
the power side voltage acquisition terminal acquires power side phase and amplitude, the three-phase voltage is symmetrical three-phase voltage, and the phase and amplitude relation is as follows:
And (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
the decomposed vector graph is shown in fig. 9.
The C-phase disconnection can be judged by comparing the voltage relationship between the power supply side and the load side, and the power supply side and the load side are not grounded.
3. C phase disconnection, power source side grounding, load side non-grounding
A power supply side:
the power supply side voltage acquisition terminal acquires the phase and the amplitude of the power supply side, and the phase and the amplitude are in the following relation because the grounding phase C of the power supply side is zero, the three-phase voltage is asymmetric three-phase voltage and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
the decomposed vector graph is shown in fig. 10.
And (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
the decomposed vector graph is shown in fig. 11.
The C-phase disconnection can be judged by comparing the voltage relationship between the power supply side and the load side, and the power supply side and the load side are not grounded.
4. C phase disconnection, power source side grounding and load side grounding
The power supply side is the same as the load side:
the power supply side voltage acquisition terminal acquires power supply side phase and amplitude, and the three-phase voltage is asymmetric three-phase voltage and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method because the grounding C phase is zero, and the phase and amplitude relations are as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
the decomposed vector graph is shown in fig. 12.
The C-phase source side and the load side can be judged to be grounded by comparing the power source side and the load side voltage relationship.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.
Claims (1)
1. A distribution network line fault type judgment method based on voltage characteristics is characterized in that:
the method comprises the following steps: judging a fault phase and grounding conditions of the power supply side and the load side according to the phase, amplitude and voltage relations of the power supply side and the load side;
the method specifically comprises the following steps:
suppose a phase a failure:
(1) when the two sides of the circuit are disconnected and not grounded, the phase and amplitude of the voltage on the power supply side are unchanged, the voltage on the load side is reduced, the phase is opposite to the phase before the fault, and the disconnection and non-ground fault of the circuit is judged;
(2) when the load side is not grounded, the voltage fault phase of the power side is 0, the amplitude of the other two phase voltages is 1.732 times of the original value, the phase deviation is 30 degrees, the zero sequence voltage is opposite to the original A phase voltage in phase and has the same amplitude, the load side broken line phase voltage is smaller, the phase is opposite to the phase before the fault, and the broken line power side is grounded and the load side is not grounded;
(3) when the power supply side is not grounded after disconnection and the load side is grounded: the phase of the voltage at the power supply side is shifted, the amplitude is increased, the shifting angle and the amplitude increasing amplitude are related to the impedance of the transformer winding at the load side, and the fault phase voltage at the load side is 0;
(4) when the two sides are grounded in a broken line mode or in a single-phase ground mode without breaking the line: the fault phase voltage of the power supply side and the fault phase voltage of the load side are 0, the phase of the other phase voltages deviates 30 degrees, and the amplitude is 1.732 times of the original amplitude;
assume a phase C fault:
(1) c phase disconnection, no ground at power supply side and ground at load side
A power supply side:
the power side voltage acquisition terminal acquires power side phase and amplitude, the three-phase voltage is symmetrical three-phase voltage, and the phase and amplitude relation is as follows:
no negative sequence and zero sequence components, wherein:
is the voltage of the A-phase,
is the phase voltage of the B phase,
the voltage is C phase voltage, and U is standard voltage amplitude;
and (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequenceComponent (b):
wherein:
is the voltage of the A-phase,
is the phase voltage of the B phase,
is C phase voltage, U is standard voltage amplitude,
is zero-sequence voltage when the phase C fails,
is the positive sequence voltage when the C phase fails,
negative sequence voltage when C phase fault occurs;
judging that the C phase is disconnected, the power supply side is not grounded, and the load side is grounded by comparing the voltage relationship between the power supply side and the load side;
(2) c phase disconnection, no ground on power supply side and no ground on load side
A power supply side:
the power side voltage acquisition terminal acquires power side phase and amplitude, the three-phase voltage is symmetrical three-phase voltage, and the phase and amplitude relation is as follows:
and (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
judging that the C phase is disconnected and the power supply side and the load side are not grounded by comparing the voltage relation of the power supply side and the load side;
(3) c phase disconnection, power source side grounding, load side non-grounding
A power supply side:
the power supply side voltage acquisition terminal acquires the phase and the amplitude of the power supply side, and the phase and the amplitude are in the following relation because the grounding phase C of the power supply side is zero, the three-phase voltage is asymmetric three-phase voltage and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
and (3) loading side:
the load side causes three-phase asymmetry due to C-phase line break, and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method, and the phase and amplitude relationship is as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
judging that the C phase is disconnected and the power supply side and the load side are not grounded by comparing the voltage relation of the power supply side and the load side;
(4) c phase disconnection, power source side grounding and load side grounding
The power supply side is the same as the load side:
the power supply side voltage acquisition terminal acquires power supply side phase and amplitude, and the three-phase voltage is asymmetric three-phase voltage and is decomposed into positive sequence, negative sequence and zero sequence components by a symmetric component method because the grounding C phase is zero, and the phase and amplitude relations are as follows:
phase voltage phase relationship:
zero-sequence component:
positive sequence component:
negative sequence component:
and comparing the voltage relationship between the power supply side and the load side to judge that the C phase source side and the load side are grounded.
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| CN109870631A (en) * | 2019-03-05 | 2019-06-11 | 贵州电网有限责任公司 | A kind of distribution line nature of trouble confirmation method based on voltage relationship comparison |
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| CN111856210B (en) * | 2020-07-27 | 2023-02-21 | 云南电力技术有限责任公司 | Method and device for judging fault type of power distribution network line |
| CN112433084B (en) * | 2020-11-18 | 2023-10-20 | 云南电网有限责任公司电力科学研究院 | Method and device for judging overvoltage reason of low-voltage transformer area |
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