CN112054487A - Single-phase earth fault judgment and processing method for direct-distribution new energy power plant - Google Patents
Single-phase earth fault judgment and processing method for direct-distribution new energy power plant Download PDFInfo
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- CN112054487A CN112054487A CN201910484706.2A CN201910484706A CN112054487A CN 112054487 A CN112054487 A CN 112054487A CN 201910484706 A CN201910484706 A CN 201910484706A CN 112054487 A CN112054487 A CN 112054487A
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- 238000003672 processing method Methods 0.000 title claims description 6
- 230000007935 neutral effect Effects 0.000 claims description 16
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 230000007547 defect Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Classifications
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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
- H02H7/261—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 involving signal transmission between at least two stations
- H02H7/262—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 involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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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
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
When the new energy power plant is connected to a power grid transformer substation through a direct distribution connecting line, a high-resistance permanent single-phase earth fault is judged and processed through differential earth line selection, and a low-resistance permanent single-phase earth fault is processed through differential zero-sequence protection time constant value configuration.
Description
Technical Field
The invention is mainly used for judging and processing the single-phase earth fault of a direct-distribution new energy power plant, in particular to a method for judging and processing the single-phase earth fault of the direct-distribution new energy power plant, which is suitable for judging and processing the single-phase earth fault of the new energy accessed into a power grid through the direct-distribution.
Background
The existing small-resistance grounding mode is widely applied to neutral point grounding of a new energy power plant to limit internal overvoltage, when a single-phase grounding fault occurs, a fault line is cut off through zero sequence protection, but the grounding mode has the biggest defect that once a power distribution network is subjected to high-resistance grounding, zero sequence protection is failed, and the fault line cannot be selected and cut off in time. In addition, a plurality of direct-distribution new energy power plants exist, namely, the bus station is converged and then is not boosted by the booster station, and the bus station is directly connected to a transformer substation of an external power grid through a connecting line. Therefore, the connecting line can be cut off when a single-phase earth fault occurs in an external power grid or a new energy power plant. The impact on the power grid or the new energy power plant can be caused, and the safe and stable operation of the power grid and the new energy power plant is influenced.
The mode that the new energy power plant is connected into the power grid transformer substation through the direct distribution tie line is adopted, no matter whether the new energy power plant or the feeder line of the power grid transformer substation has single-phase earth fault, the zero sequence current of the earth fault feeder line is IH0=Ic1+Ic2+Ir1+Ir2The zero sequence current flowing through the connecting line is IL0=Ic2+Ir2Namely, one side where single-phase grounding occurs selects a fault line or starts zero-sequence protection to remove the fault line, and meanwhile, the transformer substation or the new energy power plant on the other side selects a tie line grounding (mis-selection) or starts zero-sequence protection to remove the tie line (mis-operation).
Disclosure of Invention
Aiming at the problems, the invention provides a single-phase earth fault judgment and processing method suitable for a direct-distribution new energy power plant, which is characterized by comprising the following steps: when the new energy power plant is connected to a power grid transformer substation through a direct distribution tie line, intelligent resistor complete sets are installed at neutral points of the power grid transformer substation and the new energy power plant, and each feeder line is provided with zero sequence protection.
The high-resistance permanent single-phase earth fault is judged and processed through differential earth line selection, and when the neutral point of the power grid shifts voltage UN<UGLWhen the fault occurs, the fault is judged to be a feeder fault if a new energy power plant reports that any one side of the new energy power plant and a direct distribution tie line access power grid transformer substation reports that a feeder is grounded and the other side reports that the direct distribution tie line is grounded, and the fault can be eliminated only by cutting off the faulty feeder; if the new energy power plant and the direct distribution tie line are connected into the power grid transformer substation and the direct distribution tie line is selected to be grounded, the tie line is cut off to remove the fault.
The low-resistance permanent single-phase earth fault is processed by the configuration of the fixed value of the differential zero-sequence protection time when the displacement voltage U of the neutral point of the power grid is processedN≥UGLThe device starts zero sequence protection to cut off fault line, the fixed value of zero sequence protection current of the feeder line is set according to 1.5-2.0 times of the maximum capacitance current of the feeder line, and the time fixed value of the zero sequence protection of the feeder line is T1The time constant value of the zero sequence protection of the tie line is T2，T2>T1When the feeder line has single-phase low earth fault, the zero sequence protection mis-switching tie line can not be started.
UNShifting voltage when the neutral point of the power grid; i isH0For ground fault feedersZero sequence current; u shapeGLThe critical value of the neutral point displacement voltage of the high-resistance earth fault and the low-resistance earth fault; i isL0Is zero sequence current flowing through the tie line; i isc1The external network transformer substation is used for carrying out capacitance current to ground; i isc2The capacitance current to ground of the new energy power plant; i isr1The current is a resistive current output by a dynamic intelligent resistor of the external network transformer substation in fault; i isr2The current is a resistive current output by a dynamic intelligent resistor of the new energy power plant during fault; t is1Setting a time value for zero sequence protection of the feeder line; t is2Setting a time value for zero sequence protection of the tie line; the external network transformer substation refers to a transformer substation of a power supply department of a new energy power plant accessed to a power grid.
U in permanent high-resistance earth faultN<UGLAnd the permanent high-resistance grounding fault treatment is processed by scheduling according to the grounding line selection result of the dynamic intelligent resistance complete equipment of the transformer substation and the new energy power plant.
U in permanent low-resistance earth faultN≥UGLThe permanent low-resistance earth fault is removed by zero sequence protection, and the fault is accurately processed by differential configuration of time constant values of the zero sequence protection.
The invention has the following advantages:
1. because the high-resistance grounding fault can be accurately selected and the fault line can be cut off quickly when the high-resistance grounding fault occurs in the power grid, the problem of high-resistance dead zone of a small-resistance grounding mode is solved.
2. When a low-resistance earth fault occurs in the power distribution network, the fault area isolation is realized by the differential matching of the zero sequence protection time constant values and by disconnecting the intelligent switches of the corresponding nodes, so that the fault power failure range is reduced.
Detailed Description
When the new energy power plant is connected to a power grid transformer substation through a direct distribution tie line, intelligent resistor complete sets are installed at neutral points of the power grid transformer substation and the new energy power plant, and each feeder line is provided with zero sequence protection.
The high-resistance permanent single-phase earth fault is judged and processed through differential earth line selection, and when the neutral point of the power grid shifts voltage UN<UGLWhen the occurrence of permanence is high, the determination is madeWhen any one side of a new energy power plant and a transformer substation accessed to a power grid through a direct distribution tie line reports that a feeder line is grounded, and the other side reports that the direct distribution tie line is grounded, the fault is the feeder line fault, and the fault can be eliminated only by cutting off the faulty feeder line; if the new energy power plant and the direct distribution tie line are connected into the power grid transformer substation and the direct distribution tie line is selected to be grounded, the tie line is cut off to remove the fault.
The low-resistance permanent single-phase earth fault is processed by the configuration of the fixed value of the differential zero-sequence protection time when the displacement voltage U of the neutral point of the power grid is processedN≥UGLThe device starts zero sequence protection to cut off fault line, the fixed value of zero sequence protection current of the feeder line is set according to 1.5-2.0 times of the maximum capacitance current of the feeder line, and the time fixed value of the zero sequence protection of the feeder line is T1The time constant value of the zero sequence protection of the tie line is T2，T2>T1When the feeder line has single-phase low earth fault, the zero sequence protection mis-switching tie line can not be started.
UNShifting voltage when the neutral point of the power grid; i isH0Zero sequence current for a ground fault feeder; u shapeGLThe critical value of the neutral point displacement voltage of the high-resistance earth fault and the low-resistance earth fault; i isL0Is zero sequence current flowing through the tie line; i isc1The external network transformer substation is used for carrying out capacitance current to ground; i isc2The capacitance current to ground of the new energy power plant; i isr1The current is a resistive current output by a dynamic intelligent resistor of the external network transformer substation in fault; i isr2The current is a resistive current output by a dynamic intelligent resistor of the new energy power plant during fault; t is1Setting a time value for zero sequence protection of the feeder line; t is2Setting a time value for zero sequence protection of the tie line; the external network transformer substation refers to a transformer substation of a power supply department of a new energy power plant accessed to a power grid.
Permanent high resistance ground fault, UN<UGLAnd the permanent high-resistance grounding fault treatment is processed by scheduling according to the grounding line selection result of the dynamic intelligent resistance complete equipment of the transformer substation and the new energy power plant.
U in permanent low-resistance earth faultN≥UGLPermanent low-resistance earth fault composed ofAnd the zero sequence protection removes the fault, and the precise processing of the fault is realized by the differential configuration of the time constant value of the zero sequence protection.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (3)
1. A single-phase earth fault judgment and processing method for a direct-distribution new energy power plant is characterized by comprising the following steps: when a new energy power plant is accessed to a power grid transformer substation through a direct distribution tie line, intelligent resistor complete sets are installed at neutral points of the power grid transformer substation and the new energy power plant, and each feeder line is provided with zero sequence protection;
the high-resistance permanent single-phase earth fault is judged and processed through differential earth line selection, and when the neutral point of the power grid shifts voltage UN<UGLWhen the fault occurs, the fault is judged to be a feeder fault if a new energy power plant reports that any one side of the new energy power plant and a direct distribution tie line access power grid transformer substation reports that a feeder is grounded and the other side reports that the direct distribution tie line is grounded, and the fault can be eliminated only by cutting off the faulty feeder; if the new energy power plant and the direct distribution interconnection line are accessed to the power grid transformer substation and the direct distribution interconnection line is selected to be grounded, the interconnection line is cut off to remove the fault;
the low-resistance permanent single-phase earth fault is processed by the configuration of the fixed value of the differential zero-sequence protection time when the displacement voltage U of the neutral point of the power grid is processedN≥UGLThe device starts zero sequence protection to cut off fault line, the fixed value of zero sequence protection current of the feeder line is set according to 1.5-2.0 times of the maximum capacitance current of the feeder line, and the time fixed value of the zero sequence protection of the feeder line is T1The time constant value of the zero sequence protection of the tie line is T2，T2>T1When the feeder line has a single-phase low-earth fault, the zero-sequence protection mis-switching tie line cannot be started;
UNshifting voltage when the neutral point of the power grid; i isH0Zero sequence current for a ground fault feeder; u shapeGLThe critical value of the neutral point displacement voltage of the high-resistance earth fault and the low-resistance earth fault; i isL0Is zero sequence current flowing through the tie line; i isc1The external network transformer substation is used for carrying out capacitance current to ground; i isc2The capacitance current to ground of the new energy power plant; i isr1The current is a resistive current output by a dynamic intelligent resistor of the external network transformer substation in fault; i isr2The current is a resistive current output by a dynamic intelligent resistor of the new energy power plant during fault; t is1Setting a time value for zero sequence protection of the feeder line; t is2Setting a time value for zero sequence protection of the tie line; the external network transformer substation refers to a transformer substation of a power supply department of a new energy power plant accessed to a power grid.
2. A single-phase earth fault judgment and processing method for a direct-distribution new energy power plant is characterized by comprising the following steps: permanent high resistance ground fault, UN<UGLAnd the permanent high-resistance grounding fault treatment is processed by scheduling according to the grounding line selection result of the dynamic intelligent resistance complete equipment of the transformer substation and the new energy power plant.
3. A single-phase earth fault judgment and processing method for a direct-distribution new energy power plant is characterized by comprising the following steps: u in permanent low-resistance earth faultN≥UGLThe permanent low-resistance earth fault is removed by zero sequence protection, and the fault is accurately processed by differential configuration of time constant values of the zero sequence protection.
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