CN111579927B - Disconnection protection judgment method and device suitable for single-side power transmission line - Google Patents
Disconnection protection judgment method and device suitable for single-side power transmission line Download PDFInfo
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- CN111579927B CN111579927B CN202010440181.5A CN202010440181A CN111579927B CN 111579927 B CN111579927 B CN 111579927B CN 202010440181 A CN202010440181 A CN 202010440181A CN 111579927 B CN111579927 B CN 111579927B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
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Abstract
The invention discloses a disconnection protection judgment method suitable for a unilateral power transmission line, which comprises the following steps: collecting voltage, current and switch position information on two sides of a circuit; and the single-phase line break fault is quickly identified by combining current and switch information according to the change of the amplitude phase of line voltages on two sides of the line before and after line break. The invention also discloses a corresponding protection device. The scheme can complete judgment within 100ms of the occurrence of the line break, can cut off the power supply within 200ms, solves the problem that the line break fault of the power transmission line cannot be quickly judged, and is suitable for the power transmission line with a single-side power supply under various environments, particularly the operating environment in which the line break of overhead lines such as forest farms, grasslands, petrochemical industries and the like easily causes fire or electric shock accidents.
Description
Technical Field
The invention belongs to the technical field of power system protection control, and relates to a method and a device for quickly judging disconnection protection of a single-side power transmission line.
Background
Due to mechanical external force, construction quality, aging and the like, a disconnection fault is a typical fault type of the power transmission line. The disconnection of the overhead line can cause the occurrence of ground faults, and easily causes electric shock to people and livestock or fire; in large industrial enterprises, cable lines are mostly adopted for power transmission, and when a disconnection fault occurs, the cable lines can cause great damage to electric equipment such as a motor, so that the disconnection fault is very necessary to be quickly identified and removed. Especially in overhead lines of forest farms, grasslands and chemical enterprises, if the power supply can be cut off before the line falls to the ground after the line is broken, the occurrence of hazards such as fire disasters can be avoided.
At present, in a power system, the problem caused by line disconnection fault is solved through zero sequence overcurrent protection, grounding line selection, negative sequence overcurrent protection and non-full-phase protection. These methods are based on the actual hazard caused by a fault after a line break. If the zero sequence overcurrent protection can identify the grounding fault after the overhead line is broken, but the grounding happens at the moment, even the hazards such as fire hazard and the like are caused; negative sequence overcurrent protection and non-full phase protection also add a long time delay for preventing false operation, and can not identify the broken line fault in light load. Therefore, a targeted rapid identification method for the disconnection fault is not available at present.
Some research institutions try to judge whether the line is broken according to the current change in the line after the line is broken, but the method cannot be applied to the light-load or no-load operation condition; some research organizations try to judge according to the amplitude of a certain side voltage or the magnitude of a sequence component of the voltage, but the methods are easily interfered by an out-of-range fault and cannot work well.
Disclosure of Invention
The invention aims to provide a disconnection protection judgment method and a disconnection protection judgment device suitable for a single-side power transmission line, so as to solve the problem of quick judgment of single-phase disconnection faults of the transmission line.
In order to achieve the purpose, the following technical scheme is adopted in the application:
on one hand, the invention provides a disconnection protection judgment method suitable for a single-side power transmission line, which comprises the following steps:
collecting voltage, current and switch position information on two sides of a circuit;
judging the disconnection fault, and judging that the disconnection fault occurs when the following disconnection criterion is met and the set time is kept; the disconnection criterion comprises the following steps:
(1) the voltages of the three phase lines on the power supply side are all larger than a fixed voltage value;
(2) the amplitude difference between only one line voltage on the load side and the corresponding line voltage on the power supply side is smaller than a differential pressure fixed value, the phase difference is smaller than a phase difference fixed value, and the line voltage is called as a normal line voltage;
(3) the voltage amplitude of the other two lines of the load side is changed to be half of the amplitude of the normal line voltage, and the phase of the other two line voltages is opposite to the phase of the normal line voltage;
(4) the broken line phase currents on the two sides of the power supply side and the load side are both smaller than a current fixed value;
(5) the switches on both sides are closed.
In a preferred technical scheme, the method further comprises the step of further judging the line breaking phase after judging that the line breaking fault occurs, and the specific method comprises the following steps: the two phases related to the normal line voltage are normal phases, and one phase except the normal phase is a broken line phase.
In the preferred technical scheme, when the line is judged to have a broken line fault, the breaker is immediately actuated and driven to trip off the breaker at the power supply side to remove the fault.
In a preferred technical solution, before the disconnection fault determination, the method further includes the steps of: setting a charging completion flag bit after all charging conditions are met and a preset charging delay is kept, and allowing disconnection judgment when the charging completion flag bit is in a set state; the charging conditions include: (1) the switches on the two sides are both in the closed position; (2) the amplitude difference of the corresponding line voltages at the two sides is smaller than a constant differential pressure value, and the phase angle difference is smaller than a constant phase difference value; (3) the current difference between the two sides is less than the difference fixed value.
In a preferred technical scheme, before the disconnection fault determination, the method further comprises the step of starting disconnection protection, specifically: and when the charging completion flag bit is in a set state and when the phase angle difference of the line voltages on the two sides is greater than the phase angle fixed value or the amplitude difference of the line voltages on the two sides is greater than the differential pressure fixed value, the line breakage judgment is allowed.
In the preferred technical scheme, any one of the following conditions is met, namely, the disconnection protection is discharged, and the flag bit after charging is cleared; the discharge conditions include: (1) the switches on either side are separated; (2) the amplitude difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (3) the phase angle difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (4) the current difference flow on the two sides is greater than the difference flow fixed value; (5) PT disconnection; (6) and (5) breaking the CT line.
On the other hand, the invention also provides a disconnection protection device suitable for the single-side power transmission line, which comprises the following components:
a collecting unit: the circuit is used for collecting voltage, current and switch position information on two sides of the circuit;
disconnection fault determination unit: when the following disconnection criterion is met and the set time is kept, the disconnection fault is judged to occur; the disconnection criterion comprises the following steps:
(1) the voltages of the three phase lines on the power supply side are all larger than a fixed voltage value;
(2) the amplitude difference between only one line voltage on the load side and the corresponding line voltage on the power supply side is smaller than a differential pressure fixed value, the phase difference is smaller than a phase difference fixed value, and the line voltage is called as a normal line voltage;
(3) the voltage amplitude of the other two lines of the load side is changed to be half of the amplitude of the normal line voltage, and the phase of the other two line voltages is opposite to the phase of the normal line voltage;
(4) the broken line phase currents on the two sides of the power supply side and the load side are both smaller than a current fixed value;
(5) the switches on both sides are closed.
In a preferred technical solution, the method further comprises a fault phase determining unit: the two phases related to the normal line voltage are normal phases, and one phase except the normal phase is a broken line phase.
In a preferred embodiment, the apparatus further comprises an action unit: and when the line judges the disconnection fault, the circuit breaker acts immediately and is driven to trip off the circuit breaker at the power supply side to remove the fault.
In a preferred technical solution, the charging device further comprises a charging unit: setting a charging completion flag bit after all charging conditions are met and a preset charging delay is kept, and enabling a disconnection fault determination unit when the charging completion flag bit is in a set state; the charging conditions include: (1) the switches on the two sides are both in the closed position; (2) the amplitude difference of the corresponding line voltages at the two sides is smaller than a constant differential pressure value, and the phase angle difference is smaller than a constant phase difference value; (3) the current difference between the two sides is less than the difference fixed value.
In a preferred technical scheme, the method further comprises the following steps: a disconnection protection starting unit: and when the charging is finished, the flag bit is in a set state, and when the phase angle difference of the line voltages on the two sides is greater than the phase angle fixed value or the amplitude difference of the line voltages on the two sides is greater than the differential pressure fixed value, the disconnection fault judgment unit is enabled.
In a preferred technical scheme, the method further comprises the following steps: a discharge unit: discharging the disconnection protection and clearing the flag bit after the charging is finished when any one of the following conditions is met; the discharge conditions include: (1) the switches on either side are separated; (2) the amplitude difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (3) the phase angle difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (4) the current difference flow on the two sides is greater than the difference flow fixed value; (5) PT disconnection; (6) and (5) breaking the CT line.
The probability of two-phase simultaneous wire break and three-phase simultaneous wire break is extremely low, so the application does not refer to the method.
Compared with the prior art, the invention has the following advantages and progresses:
(1) and (5) rapidly identifying the disconnection fault. The protection device collects voltage, current and switch position information on two sides of a line, sets charging and discharging conditions to identify the running state, identifies the line breaking fault by combining the current and switch information according to the change of line voltage amplitude phases on two sides of the line before and after line breaking, can quickly identify the single-phase line breaking fault and protect the action within 100ms of the line breaking, and can remove the fault within 200ms by considering the cooperation with an external switch; the fault is removed as far as possible before the overhead line is grounded after the line is broken, so that accidents such as fire disasters and the like are prevented.
(2) The device is not influenced by the load size, and can be self-adaptive to various operation modes of light load and heavy load;
(3) the line voltage is adopted for judgment, and the influence of a neutral point operation mode is avoided.
(4) Meanwhile, the electrical quantities at two ends of the line are compared, so that protection misoperation or failure operation caused by an external fault is avoided, and the anti-interference capability is strong;
(5) the method can be realized on the basis of the existing optical fiber differential protection without adding a protection device.
(6) The disconnection phase selection can be completed after the disconnection occurs.
Drawings
Fig. 1 is a schematic diagram of an embodiment 1 of a disconnection protection determination method suitable for a single-side power transmission line;
fig. 2 is a schematic diagram of an embodiment 2 of a disconnection protection determination method suitable for a single-side power transmission line;
fig. 3 is a schematic diagram of an embodiment 3 of a disconnection protection determination method suitable for a single-side power transmission line;
fig. 4 is a schematic diagram of an embodiment 4 of a disconnection protection determination method suitable for a single-side power transmission line;
fig. 5 is a schematic diagram of an embodiment 5 of a disconnection protection determination method suitable for a single-side power transmission line;
fig. 6 is a schematic diagram of an embodiment 6 of a disconnection protection determination method suitable for a single-side power transmission line;
FIG. 7 is a schematic diagram of a disconnection protection system;
FIG. 8 is a system equivalent circuit diagram;
FIG. 9 is a vector diagram of the load side voltage before and after a line break;
fig. 10 is a schematic diagram of a disconnection protection device suitable for a single-side power transmission line.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Example 1:
fig. 1 is a schematic diagram of a disconnection protection determination method suitable for a single-side power transmission line according to embodiment 1 of the present invention, including the steps of:
s10: collecting voltage, current and switch position information on two sides of a circuit;
s20: judging the disconnection fault, and judging that the disconnection fault occurs when the following disconnection criterion is met and the set time is kept; the disconnection criterion comprises the following steps:
(1) the voltages of the three phase lines on the power supply side are all larger than a fixed voltage value;
(2) the amplitude difference between only one line voltage on the load side and the corresponding line voltage on the power supply side is smaller than a differential pressure fixed value, the phase difference is smaller than a phase difference fixed value, and the line voltage is called as a normal line voltage;
(3) the voltage amplitude of the other two lines of the load side is changed to be half of the amplitude of the normal line voltage, and the phase of the other two line voltages is opposite to the phase of the normal line voltage;
(4) the broken line phase currents on the two sides of the power supply side and the load side are both smaller than a current fixed value;
(5) the switches on both sides are closed.
Another embodiment 2 of the present invention, on the basis of embodiment 1, further includes, after step S20, step S30: when the line break fault is judged, further judging a line break phase, wherein the specific method comprises the following steps: the two phases related to the normal line voltage are normal phases, and one phase except the normal phase is a broken line phase.
Another embodiment 3 of the present invention, on the basis of embodiment 1, further includes, after step S20, step S40: and when the line judges the disconnection fault, the circuit breaker acts immediately and is driven to trip off the circuit breaker at the power supply side to remove the fault.
Another embodiment 4 of the present invention is, on the basis of embodiment 1, before the step S20, further including a step S11 of protecting charging: when all charging conditions are met and the preset charging delay is kept, the charging completion zone bit is set, and when the charging completion zone bit is in a set state, disconnection judgment is allowed. The charging conditions include: (1) the switches on the two sides are both in the closed position; (2) the amplitude difference of the corresponding line voltages at the two sides is smaller than a constant differential pressure value, and the phase angle difference is smaller than a constant phase difference value; (3) the current difference between the two sides is less than the difference fixed value.
Another embodiment 5 of the present invention, on the basis of embodiment 4, after step S11, and before step S20, further includes step S12 of starting disconnection protection, specifically: and when the charging completion flag bit is in a set state and when the phase angle difference of the line voltages on the two sides is greater than the phase angle fixed value or the amplitude difference of the line voltages on the two sides is greater than the differential pressure fixed value, the line breakage judgment is allowed.
Another embodiment 6 of the present invention is based on embodiment 4, and further includes discharge detection. Discharging the disconnection protection and clearing the flag bit after the charging is finished when any one of the following conditions is met; the discharge conditions include: (1) the switches on either side are separated; (2) the amplitude difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (3) the phase angle difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (4) the current difference flow on the two sides is greater than the difference flow fixed value; (5) PT disconnection; (6) and (5) breaking the CT line.
With reference to fig. 7 to 9, another embodiment 7 of the present invention will be described in detail. In this embodiment, the load side protection device is responsible for collecting information of the load side and transmitting the information to the power supply side. The power supply side protection device collects the information of the power supply side, receives the information of the load side and simultaneously carries out disconnection protection logic judgment. The method comprises the following specific steps:
step (1) collecting voltage, current and switch position information at two sides of a circuit. As shown in fig. 7, protection devices may be disposed on both sides of the line, and the devices on both sides are connected by communication means (such as optical fibers). The load side protection device is responsible for collecting current, voltage and switch position information of the load side and transmitting the collected current, voltage and switch position information to the power supply side in a communication mode. The power supply side protection device collects current, voltage and switch position of the power supply side and receives current, voltage and switch position information of the load side.
Step (2) the power supply side protection device sets charge and discharge conditions to identify the running state; when all charging conditions are met and the preset charging delay is kept, the charging completion zone bit is set, and when the charging completion zone bit is in a set state, disconnection judgment is allowed. The charging condition of the disconnection protection is
The switch positions on the two sides are both closed;
two sides corresponding to line voltages (c)
And
and
and
) The phase angle difference is smaller than the phase difference fixed value, and the amplitude difference is smaller than the pressure difference fixed value.
And thirdly, the three-phase differential current of the current on the two sides is smaller than a differential current fixed value.
And meanwhile, the charging conditions are met, and the disconnection protection charging is finished after the charging time delay.
Discharging the disconnection protection if any one of the following conditions is met, and clearing the flag bit after the charging is finished; the wire break protection discharge conditions are as follows:
firstly, the switch position on one side is a position division;
the phase angle difference of the line voltages on the two sides is larger than the fixed value of the phase angle and exceeds 500 ms;
the voltage amplitude difference of the two sides is larger than the constant value of the pressure difference and exceeds 500 ms;
fourthly, the current differential flow at the two sides is greater than the differential flow fixed value and is kept for 500 ms;
PT disconnection;
sixthly, CT disconnection.
And seventhly, receiving manual tripping signals including manual tripping and remote control closing.
When the charging completion flag bit is in a set state; when any one of the following conditions is met, the disconnection protection is started
Firstly, the phase angle difference of line voltages at two sides is greater than a phase angle fixed value;
secondly, the amplitude difference of the line voltages at the two sides is larger than a fixed differential pressure value;
and (5) carrying out disconnection logic judgment after the disconnection protection is started, wherein the disconnection judgment conditions are as follows:
firstly, three line voltages at the power supply side are all larger than a fixed value;
secondly, the amplitude difference of the corresponding line voltage of only one line voltage and the corresponding line voltage of the power supply side is smaller than a differential pressure fixed value, and the phase difference is smaller than a phase difference fixed value;
the line voltage is called normal line voltage, two phases related to the normal line voltage are called normal phases, and one phase except the normal phases is called a broken line phase;
voltage amplitudes of the other two line voltages on the load side become half of the amplitudes of the normal line voltages, and the phases of the voltages are opposite to the phases of the normal line voltages;
the phase current of broken lines at the two sides of the power supply side and the load side is smaller than a current fixed value;
sixthly, the switches on the two sides are all closed.
And if the conditions are met and the time lasts for 80ms, the circuit is judged to be a disconnection fault.
And (6) when the line judges that the line is broken, immediately acting and driving the breaker to trip off the breaker at the power supply side to remove the fault.
Fig. 8 is a system equivalent circuit diagram of phase disconnection, and fig. 9 depicts the voltage changes on both sides before and after phase a disconnection. (a) Is a voltage vector diagram in normal operation, and (b) is a voltage vector diagram after the A phase is disconnected. B. The C phase is broken similarly to the A phase.
Fig. 10 shows an embodiment of the disconnection protection device suitable for a single-side power transmission line according to the present invention, which includes a collection unit and a disconnection fault determination unit. Wherein:
a collecting unit: the method is used for collecting voltage, current and switch position information on two sides of the circuit.
Disconnection fault determination unit: and when the following disconnection criterion is met and the set time is kept, the disconnection fault is judged to occur. The disconnection criterion comprises the following steps:
(1) the voltages of the three phase lines on the power supply side are all larger than a fixed voltage value;
(2) the amplitude difference between only one line voltage on the load side and the corresponding line voltage on the power supply side is smaller than a differential pressure fixed value, the phase difference is smaller than a phase difference fixed value, and the line voltage is called as a normal line voltage;
(3) the voltage amplitude of the other two lines of the load side is changed to be half of the amplitude of the normal line voltage, and the phase of the other two line voltages is opposite to the phase of the normal line voltage;
(4) the broken line phase currents on the two sides of the power supply side and the load side are both smaller than a current fixed value;
(5) the switches on both sides are closed.
In a preferred embodiment, on the basis of the above embodiment, the present invention further includes a fault phase determining unit: the two phases related to the normal line voltage are normal phases, and one phase except the normal phase is a broken line phase.
In a preferred embodiment, the above embodiment is further based on an action unit: and when the line judges the disconnection fault, the circuit breaker acts immediately and is driven to trip off the circuit breaker at the power supply side to remove the fault.
In a preferred embodiment, on the basis of the above embodiment, the charging unit further includes: setting a charging completion flag bit after all charging conditions are met and a preset charging delay is kept, and enabling a disconnection fault determination unit when the charging completion flag bit is in a set state; the charging conditions include: (1) the switches on the two sides are both in the closed position; (2) the amplitude difference of the corresponding line voltages at the two sides is smaller than a constant differential pressure value, and the phase angle difference is smaller than a constant phase difference value; (3) the current difference between the two sides is less than the difference fixed value.
In a preferred embodiment, on the basis of the above embodiment, the method further comprises: a disconnection protection starting unit: and when the charging is finished, the flag bit is in a set state, and when the phase angle difference of the line voltages on the two sides is greater than the phase angle fixed value or the amplitude difference of the line voltages on the two sides is greater than the differential pressure fixed value, the disconnection fault judgment unit is enabled.
In a preferred embodiment, on the basis of the above embodiment, the method further comprises: a discharge unit: discharging the disconnection protection and clearing the flag bit after the charging is finished when any one of the following conditions is met; the discharge conditions include: (1) the switches on either side are separated; (2) the amplitude difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (3) the phase angle difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (4) the current difference flow on the two sides is greater than the difference flow fixed value; (5) PT disconnection; (6) and (5) breaking the CT line.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (12)
1. A disconnection protection judgment method suitable for a single-side power transmission line is characterized by comprising the following steps:
collecting voltage, current and switch position information on two sides of a circuit;
setting a charging completion flag bit after all charging conditions are met and a preset charging delay is kept, and allowing disconnection judgment when the charging completion flag bit is in a set state;
judging the disconnection fault, and judging that the disconnection fault occurs when the following disconnection criterion is met and the set time is kept; the disconnection criterion comprises the following steps:
(1) the voltages of the three phase lines on the power supply side are all larger than a fixed voltage value;
(2) the amplitude difference between only one line voltage on the load side and the corresponding line voltage on the power supply side is smaller than a differential pressure fixed value, the phase difference is smaller than a phase difference fixed value, and the line voltage is called as a normal line voltage;
(3) the voltage amplitude of the other two lines of the load side is changed to be half of the amplitude of the normal line voltage, and the phase of the other two line voltages is opposite to the phase of the normal line voltage;
(4) the broken line phase currents on the two sides of the power supply side and the load side are both smaller than a current fixed value;
(5) the switches on both sides are closed.
2. The disconnection protection judgment method according to claim 1, further comprising the step of further judging a disconnection phase after judging that the disconnection fault occurs, wherein the specific method comprises the steps of: the two phases related to the normal line voltage are normal phases, and one phase except the normal phase is a broken line phase.
3. The disconnection protection judging method according to claim 1, wherein the circuit breaker is operated and driven to trip off the power source side circuit breaker to remove the fault immediately after the disconnection fault is judged on the line.
4. The disconnection protection determination method according to claim 1,
the charging conditions include: (1) the switches on the two sides are both in the closed position; (2) the amplitude difference of the corresponding line voltages at the two sides is smaller than a constant differential pressure value, and the phase angle difference is smaller than a constant phase difference value; (3) the current difference between the two sides is less than the difference fixed value.
5. The disconnection protection judgment method according to claim 4, further comprising a step of starting disconnection protection before the disconnection fault judgment, specifically: and when the charging completion flag bit is in a set state and when the phase angle difference of the line voltages on the two sides is greater than the phase angle fixed value or the amplitude difference of the line voltages on the two sides is greater than the differential pressure fixed value, the line breakage judgment is allowed.
6. The disconnection protection determination method according to claim 4, wherein any one of the following conditions is satisfied, namely, the disconnection protection is discharged, and the charged flag bit is cleared; the discharge conditions include: (1) the switches on either side are separated; (2) the amplitude difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (3) the phase angle difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (4) the current difference flow on the two sides is greater than the difference flow fixed value; (5) PT disconnection; (6) and (5) breaking the CT line.
7. The utility model provides a disconnection protection device suitable for unilateral power transmission line which characterized in that includes:
a collecting unit: the circuit is used for collecting voltage, current and switch position information on two sides of the circuit;
a charging unit: setting a charging completion flag bit after all charging conditions are met and a preset charging delay is kept, and enabling a disconnection fault determination unit when the charging completion flag bit is in a set state;
disconnection fault determination unit: when the following disconnection criterion is met and the set time is kept, the disconnection fault is judged to occur; the disconnection criterion comprises the following steps:
(1) the voltages of the three phase lines on the power supply side are all larger than a fixed voltage value;
(2) the amplitude difference between only one line voltage on the load side and the corresponding line voltage on the power supply side is smaller than a differential pressure fixed value, the phase difference is smaller than a phase difference fixed value, and the line voltage is called as a normal line voltage;
(3) the voltage amplitude of the other two lines of the load side is changed to be half of the amplitude of the normal line voltage, and the phase of the other two line voltages is opposite to the phase of the normal line voltage;
(4) the broken line phase currents on the two sides of the power supply side and the load side are both smaller than a current fixed value;
(5) the switches on both sides are closed.
8. The disconnect protection device of claim 7, further comprising
A failure phase determination unit: the two phases related to the normal line voltage are normal phases, and one phase except the normal phase is a broken line phase.
9. The disconnect protection device of claim 7, further comprising
An action unit: and when the line judges the disconnection fault, the circuit breaker acts immediately and is driven to trip off the circuit breaker at the power supply side to remove the fault.
10. The disconnect protection device of claim 7, wherein the charging condition comprises: (1) the switches on the two sides are both in the closed position; (2) the amplitude difference of the corresponding line voltages at the two sides is smaller than a constant differential pressure value, and the phase angle difference is smaller than a constant phase difference value; (3) the current difference between the two sides is less than the difference fixed value.
11. The disconnection protection device of claim 10, further comprising:
a disconnection protection starting unit: and when the charging is finished, the flag bit is in a set state, and when the phase angle difference of the line voltages on the two sides is greater than the phase angle fixed value or the amplitude difference of the line voltages on the two sides is greater than the differential pressure fixed value, the disconnection fault judgment unit is enabled.
12. The disconnection protection device of claim 10, further comprising:
a discharge unit: discharging the disconnection protection and clearing the flag bit after the charging is finished when any one of the following conditions is met; the discharge conditions include: (1) the switches on either side are separated; (2) the amplitude difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (3) the phase angle difference of any line voltage on the two sides is greater than a fixed value and exceeds a time set value; (4) the current difference flow on the two sides is greater than the difference flow fixed value; (5) PT disconnection; (6) and (5) breaking the CT line.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010440181.5A CN111579927B (en) | 2020-05-22 | 2020-05-22 | Disconnection protection judgment method and device suitable for single-side power transmission line |
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| CN202010440181.5A CN111579927B (en) | 2020-05-22 | 2020-05-22 | Disconnection protection judgment method and device suitable for single-side power transmission line |
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| CN113504436B (en) * | 2021-07-23 | 2023-05-12 | 广东电网有限责任公司 | Distribution network line disconnection phase-failure diagnosis method and device based on electrical topology |
| CN114640093B (en) * | 2022-02-23 | 2023-03-24 | 北京天能继保电力科技有限公司 | Method and device for protecting broken line of distributed power transmission and distribution line |
| CN116780465A (en) * | 2023-08-23 | 2023-09-19 | 中铁电气化勘测设计研究院有限公司 | Protection method for single-phase disconnection fault of alternating-current overhead cable based on GOOSE |
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