CN110729709B - 110kV line disconnection relay protection method for measuring neutral point voltage of transformer - Google Patents

110kV line disconnection relay protection method for measuring neutral point voltage of transformer Download PDF

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CN110729709B
CN110729709B CN201911186704.1A CN201911186704A CN110729709B CN 110729709 B CN110729709 B CN 110729709B CN 201911186704 A CN201911186704 A CN 201911186704A CN 110729709 B CN110729709 B CN 110729709B
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line
phase
voltage value
power
power supply
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CN110729709A (en
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陈永明
杨茹
李静
胡航
宋丽
侯超
曹斌
汤大海
魏刚
王律
徐溯
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State Grid Jiangsu Electric Power Co ltd Zhenjiang Power Supply Branch
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State Grid Jiangsu Electric Power Co ltd Zhenjiang Power Supply Branch
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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
    • H02H7/266—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 switching on a spare supply
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
    • H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
    • 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
    • H02H7/263—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 measured values

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The invention discloses a method for measuring 110kV line disconnection relay protection of a neutral point voltage of a transformer, which comprises the steps of measuring the 110kV neutral point voltage of the 110kV transformer in a load end substation, identifying a single-phase disconnection tripping-in line breaker of the 110kV line, or starting a far-tripping 110kV line power supply side breaker through 110kV line optical fiber current differential protection, and carrying out relay protection by matching with a backup power automatic switch. The invention fully utilizes the fault characteristics of PT secondary voltage of a 110kV bus of a load end substation and 110kV neutral point voltage of a 110kV transformer when the 110kV line is in single-phase disconnection, identifies the 110kV line single-phase disconnection, is simple and feasible in matching with the backup power automatic switch, and is beneficial to safe and stable operation of a power grid.

Description

110kV line disconnection relay protection method for measuring neutral point voltage of transformer
Technical Field
The invention relates to a method for measuring 110kV line disconnection relay protection of neutral point voltage of a transformer, and belongs to the technical field of power relay protection.
Background
At present, the phenomenon of 110kV line disconnection often occurs in a power grid, the 110kV transformer powered by the 110kV line can be caused to run in a phase-lacking manner due to the line disconnection, the three-phase voltage of the transformer powered by the power supply is asymmetric, the load power supply is affected, even the 110kV neutral point of the 110kV transformer is broken down and burnt due to zero-sequence overvoltage, and the transformer is forced to be powered off and maintained. In the prior art, no relay protection device specially aiming at 110kV line disconnection exists, so a protection device and a protection method must be developed to prevent the influence of phase-lacking power supply of a transformer on a power grid and load power supply, and simultaneously prevent a 110kV neutral point of the 110kV transformer from being burnt out, so as to be beneficial to safe and stable operation of the power grid.
Disclosure of Invention
The invention aims to provide a relay protection method for measuring the neutral point voltage of a transformer and the 110kV line disconnection, which is a relay protection method for measuring the 110kV neutral point voltage of the 110kV transformer in a load-end substation, identifying a 110kV line single-phase disconnection tripping-in circuit breaker or starting a far-tripping 110kV line power supply side circuit breaker through 110kV line optical fiber current differential protection and matching with a spare power automatic switching device.
The purpose of the invention is realized by the following technical scheme:
a method for measuring 110kV line disconnection relay protection of a neutral point voltage of a transformer comprises the following steps:
method for identifying disconnection of each phase of 110kV line
Method for identifying each phase disconnection of No. 1.11 power supply incoming line circuit
Collecting a PT secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a first section of a bus of a 110kV transformer substation at a load end;
1) a-phase broken line identification method
(1) The voltage value of the PT secondary A phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary B phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is greater than the setting voltage value U3;
when the conditions are all met, a phase disconnection signal of a No. 1 110kV power supply incoming line circuit A is sent out after a delay of t 1;
2) method for identifying B-phase broken line
(1) The voltage value of the PT secondary B phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 1 110kV power incoming line B phase disconnection signal is sent out after the time delay of t 1;
3) c-phase broken line identification method
(1) The voltage value of the PT secondary C phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the voltage value of the PT secondary opening triangle of the I section of the bus is greater than a setting voltage value U3;
when the conditions are all met, a No. 1 110kV power supply incoming line C phase disconnection signal is sent out after time delay t 1;
method for identifying each phase disconnection of No. 1.22 power supply incoming line circuit
Collecting a secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a PT (potential transformer) of a II-section bus of a 110kV transformer substation at a load end;
1) a-phase broken line identification method
(1) The voltage value of a secondary A phase of a PT section II bus is smaller than a setting voltage value U1;
(2) the voltage value of the secondary B phase of the PT bus of the section II is between the upper limit and the lower limit of a setting voltage value U2;
(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 2 110kV power incoming line A phase disconnection signal is sent out after the time delay of t 1;
2) control method for B-phase broken line identification
(1) The voltage value of a secondary B phase of a PT section II bus is smaller than a setting voltage value U1;
(2) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 2 110kV line power supply incoming line B phase disconnection signal is sent out after time delay t 1;
3) control method for C-phase broken line identification
(1) The secondary C-phase voltage value of the II-section bus PT is smaller than a setting voltage value U1;
(2) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(4) the voltage value of the PT secondary opening triangle of the II section of bus is greater than a setting voltage value U3;
when the conditions are all met, a No. 2 110kV power incoming line C phase disconnection signal is sent out after a delay of t 1;
judging the conditions of a 110kV line disconnection starting trip circuit incoming line breaker and a 110kV backup power automatic switching standby power supply breaker:
2.1 judging condition of 1DL of No. 1 110kV line disconnection tripping 110kV No. 1 power supply incoming line circuit breaker 1DL or starting far tripping 110kV line power supply side circuit breaker 4DL through 110kV line optical fiber current differential protection, starting closing standby power supply circuit breaker 2DL or 3DL by 110kV backup power automatic switching
Collecting secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc and open triangular voltage 3Uo of a PT secondary A-phase voltage Ua of a first section of a bus PT of a load end 110kV transformer substation, and current of a CT at a 110kV neutral point gap of a No. 1 transformer and a No. 2 transformer,
condition 1:
the condition of a method for identifying the disconnection of each phase of a No. 1 110kV power supply incoming line circuit is met, the No. 1 110kV incoming line breaker 1DL is at a switching-on position, the 110kV neutral point voltage value of a No. 1 or No. 2 transformer is greater than a setting voltage value U4, after t2 delay, the load end transformer substation 110kV line incoming line breaker 1DL is tripped, the load end 110kV transformer substation 110kV spare power automatic switching action starts the 2DL or 3DL switching-on of a spare No. 2 110kV power supply breaker, and the transformer losing the power supply is recovered to the spare No. 2 110kV power supply to supply power; or the 1 # 110kV power line power supply side circuit breaker 4DL is tripped remotely by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection, and as the 1 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to trip the 1 # 110kV power supply incoming circuit breaker 1DL and closes the spare 2 # power supply circuit breaker 2DL or 3DL, so that the transformer losing power supply is recovered to the spare 2 # 110kV power supply for supplying power;
condition 2:
(1) the condition of each phase disconnection identification method of the No. 1 110kV power incoming line is met, and T time is opened; opening a primary pulse with T time, namely high level time;
(2) the zero sequence current 3Io of the neutral point of any main transformer on the bus is greater than a setting value I1;
when the conditions are all met and the No. 1 110kV incoming line breaker 1DL is in a switching-on position, after t3 is delayed, the No. 1 kV line incoming line breaker 1DL of the load end substation is tripped, and the No. 2 110kV power supply breaker 2DL or the No. 3kV spare power supply is started to switch on through the 110kV spare power automatic switching action of the load end substation, so that the transformer losing the power supply is recovered to the No. 2 spare 110kV power supply to supply power; or the 1 # 110kV power line power supply side circuit breaker 4DL is jumped far by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection, and as the 1 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to jump off the 1 # 110kV power supply incoming circuit breaker 1DL and closes the spare 2 # power supply circuit breaker 2DL or 3DL, so that the transformer losing power is recovered to the spare 2 # 110kV power supply for supplying power;
2.2 judge the condition of 2 # 110kV line break trip 110kV 2 power supply incoming line circuit breaker 2DL or starting the remote trip 110kV line power supply side breaker 5DL through 110kV line fiber current differential protection and the condition of 110kV backup power automatic switching starting closing backup power supply breaker 1DL or 3 DL:
collecting the current of PT secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc, open triangular voltage 3Uo and CT at 110kV neutral point gap of No. 3 transformer of load end 110kV transformer substation II section,
condition 1:
the condition of a method for identifying the disconnection of each phase of a No. 2 110kV power supply incoming line circuit is met, a No. 2 110kV incoming line breaker 2DL is at a switching-on position, the 110kV neutral point voltage value of a No. 3 transformer is greater than a setting voltage value U4, after t2 is delayed, the load-tripping end transformer substation 110kV line incoming breaker 2DL is started, the load-tripping end 110kV transformer substation 110kV spare power automatic switching action is used for starting the switching-on of a spare No. 1 110kV power supply breaker 1DL or 3DL, and the transformer losing the power supply is recovered to the spare No. 1 110kV power supply for power supply; or the 2 # 110kV power line power supply side circuit breaker 5DL is remotely tripped by starting the remote tripping function of the 2 # 110kV power line optical fiber differential protection, and as the 2 # 110kV power line loses power, the 110kV substation 110kV spare power automatic switching action at the load end starts to trip off the 2 # 110kV power incoming circuit breaker 2DL and closes the 1 # standby power circuit breaker 1DL or 3DL, so that the transformer losing power is recovered to the 1 # standby 110kV power supply for supplying power;
condition 2:
(1) the condition of the control method for identifying each phase disconnection of the No. 2 110kV power incoming line circuit meets the condition, and the T time is opened;
(2) the zero sequence current 3Io of the neutral point of any main transformer on the bus is greater than a setting value;
when the conditions are all met and the No. 2 110kV incoming line breaker 2DL is in the switching-on position, after time delay t3, tripping the No. 2kV line incoming line breaker 2DL of the load end transformer substation, starting the standby No. 1 110kV power supply breaker 1DL or 3DL to switch on by the 110kV backup power automatic switching action of the load end transformer substation, and enabling the transformer without the power supply to be recovered to the standby No. 1 110kV power supply to supply power; or the 2 # 110kV power line fiber differential protection remote tripping function is started, the 2 # 110kV power line power supply side circuit breaker 5DL is tripped remotely, and as the 2 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to trip the 2 # 110kV power incoming circuit breaker 2DL and closes the spare 12 # power circuit breaker 1DL or 3DL, so that the transformer losing power is recovered to the spare 1 # 110kV power supply for power supply.
The object of the invention can be further achieved by the following technical measures:
the method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer comprises the following steps,
the setting voltage value U1 is 1.3-1.5 times of the highest possible voltage value when the line is broken, namely the value range of the setting voltage value U1 is 42V-48V;
the upper limit value of the setting voltage value U2 is 63.8V, and the lower limit value is 52.2V;
the setting voltage value U3 is: taking a sensitivity coefficient of 1.3-1.5 according to the lowest possible voltage value of 100V when the line is broken, namely taking a value in the range of 67V-77V;
the setting voltage value U4 is: and taking a sensitivity coefficient of 1.3-1.5 according to the phase rated voltage value of 1/2V, namely taking a value in the range of 19V-22V.
The method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer comprises the following steps,
the t1 time is set to be 2-4 seconds; setting the t2 time to be 0.15-0.5 seconds; setting the t3 time to be 0.15-0.5 seconds; the opening T time is set to be 5-7 seconds; the setting value range of zero sequence current 3Io of the 110kV neutral point of the main transformer is 40-100A.
After the 110kV line is judged to be broken, a load side or power supply side circuit breaker for jumping the 110kV line is adopted, a load side substation 110kV side backup power automatic switch or a medium-low voltage side backup power automatic switch is adopted, a backup power supply circuit breaker is combined, and a bus or a transformer which runs in a phase failure due to the broken line of the 110kV line is adjusted to a backup line for power supply.
Compared with the prior art, the invention has the beneficial effects that:
the invention is used for measuring 110kV neutral point voltage of a 110kV transformer in a load end substation, identifying single-phase line break of a 110kV line, or starting a circuit breaker at a power supply side of a long-jump 110kV line through 110kV line optical fiber current differential protection, and is matched with a spare power automatic switch in a relay protection method, and has the following advantages:
1. the invention fully utilizes the fault characteristics of PT secondary voltage of a 110kV bus of a load end substation and 110kV neutral point voltage of a 110kV transformer when the 110kV line is in single-phase disconnection, identifies the 110kV line single-phase disconnection and is simple and easy to operate in cooperation with the backup power automatic switch.
2. The invention adopts the scheme that the incoming line circuit breaker of the 110kV transformer 110kV neutral point voltage is measured, the single-phase line breaking starting tripping of the 110kV line is identified, or the circuit breaker of the power supply side of the long-jump 110kV line is started through the 110kV line optical fiber current differential protection, and is matched with the backup automatic switch, the backup power supply circuit breaker is started by the 110kV backup automatic switch to switch on, so that the transformer losing the power supply is recovered to the relay protection of the power supply on the backup power supply, the influence of the phase-lacking power supply of the transformer on the power grid and the load power supply is effectively prevented, simultaneously, the 110kV transformer 110kV neutral point is prevented from being burnt, and the safe and stable operation.
Drawings
FIG. 1 is a schematic diagram of a 110kV line breaking primary system;
FIG. 2 is a vector diagram of a 110kV line disconnection;
FIG. 3 is a schematic diagram of a 110kV primary system with a broken line and a load side grounded;
FIG. 4 is a vector diagram of the grounding at the broken line and the load side of the 110kV line;
FIG. 5 is a schematic diagram of the disconnection protection of the present invention;
FIG. 6 is a primary main wiring diagram of a single bus segment of a 110kV substation;
FIG. 7 is a primary main wiring diagram of an inner bridge of a 110kV substation;
FIG. 8 is a diagram of a primary main wiring of an enlarged inner bridge of a 110kV substation;
FIG. 9 is a primary main wiring diagram of a line transformer bank of a 110kV transformer substation;
the symbols in the figures are as follows:
Figure BDA0002292566090000051
-representing a logical and relationship, i.e. the output is valid when all input conditions are fulfilled;
Figure BDA0002292566090000052
-representing a logical or relationship, i.e. the output is valid when any of the input conditions is fulfilled;
Figure BDA0002292566090000061
-represents the open T time relationship, i.e. the open T time when any of the input conditions is fulfilled.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
110kV line breakage analysis:
1.110 kV line break analysis
When the 110kV neutral point of the load side 110kV substation transformer is not grounded.
1.1110 kV line broken wire
Fig. 1 is a schematic diagram of a 110kV primary disconnection system. The 110kV side of the 220kV transformer substation on the system side is an effective grounding system; 110kV neutral points of 110kV substation transformers on the load side are not grounded and are grounded through gaps.
The electric potentials of the 110kV side power supplies of the 220kV transformer substation on the system side are respectively set as EA、EB、EC. When a certain part of the 110kV line is broken, such as phase A, the voltage of the 110kV bus of the 110kV transformer substation at the load side is obtained through analysis:
Figure BDA0002292566090000062
(1) in the formula of UA、UB、UCThe voltage of A phase, B phase and C phase of 110kV bus of 110kV transformer substation at load side is U phase0110kV transformer substation on load sideTransformer 110kV neutral point voltage, 3U0The voltage of a secondary open-delta winding of a 110kV bus voltage transformer (PT for short) of a load side 110kV substation transformer is obtained. The vector diagram is shown in fig. 2.
1.2110 kV line disconnection and load side disconnection grounding
FIG. 3 is a schematic diagram of a 110kV disconnection and load side disconnection primary grounding system. The 110kV side of the 220kV transformer substation on the system side is an effective grounding system; 110kV neutral points of 110kV substation transformers on the load side are not grounded and are grounded through gaps.
The electric potentials of the 110kV side power supplies of the 220kV transformer substation on the system side are respectively set as EA、EB、EC. When a certain part of the 110kV line is broken and the broken line of the load side is grounded, such as phase A, the voltage of the 110kV bus of the 110kV transformer substation on the load side is obtained through analysis:
Figure BDA0002292566090000063
(2) in the formula of UA、UB、UCThe voltage of A phase, B phase and C phase of 110kV bus of 110kV transformer substation at load side is U phase0Is 110kV neutral point voltage of 110kV transformer substation on load side, 3U0The voltage of a secondary open-delta winding of a 110kV bus voltage transformer (PT for short) of a load side 110kV substation transformer is obtained. The vector diagram is shown in fig. 4.
1.3110 kV line disconnection and system side disconnection point grounding
When the 110kV line is broken and the broken line of the system side is grounded, for the system side, the fault is mainly reflected in the single-phase grounding short-circuit fault of the 110kV line, so that the 110kV line protection of the 220kV transformer substation can start tripping to remove the fault (the 110kV line breaker trips to remove the fault, the 110kV line breaker is overlapped, then the single-phase grounding short-circuit fault of the 110kV line, the 110kV line protection of the 220kV transformer substation restarts tripping and removes the fault).
Analysis of 110kV neutral click-through of 110kV transformer substation in 1.4110 kV line disconnection
TABLE 1 Power frequency discharge Voltage at different gaps. By analysing the neutral point to ground voltage U of the transformer0It can be determined whether the gap is likely to break down, in conjunction with table 1.
TABLE 1 Power frequency discharge Voltage for different gaps
Tab1 Discharge voltage with power frequency of different neutral gaps
Figure BDA0002292566090000071
For the analytical result of 1.3, 3U0Has a maximum value of 150V, and a neutral point to ground voltage U0The secondary value is 50V, and the primary value is converted to obtain U0The first value, the calculation result is as follows:
Figure BDA0002292566090000072
as the discharge gap of the neutral point of the transformer is 110mm or 120mm, the power frequency withstand voltage of the neutral point of the transformer is 52kV or 53.3kV as shown in Table 1, and the maximum steady-state voltage of the neutral point of the actual transformer is about 55kV and higher than the power frequency withstand voltage value, the discharge gap can be punctured.
Analysis of 2.110 kV line breaking result
2.1110 kV line break (or and earthing at break)
For the 2 conditions of 1.1 and 1.2, the 110kV line can be used for line break protection, and the load transfer of the line break of the 110kV line can be eliminated by matching with the backup power automatic switch, so that the influence of the line break of the 110kV line on the power supply load can be prevented.
Short circuit caused by 2.2110 kV line disconnection and grounding at disconnection
For 1.3, due to the fact that short-circuit fault is caused by grounding at the broken line, tripping can be started by 110kV line protection of a 220kV transformer substation to remove the fault (the 110kV line breaker trips to remove the fault, the 110kV line breaker is overlapped, then the 110kV line single-phase grounding short-circuit fault occurs, the 220kV transformer substation 110kV line protection restarts tripping and removes the fault); because the 110kV bus corresponding to the 110kV transformer substation at the load end loses power, the load transfer of 110kV line disconnection is eliminated by the spare power automatic switching action, and the influence of the 110kV line disconnection on the power supply load is prevented.
Fault feature analysis during disconnection of 3.110 kV line
For 2 kinds of 110kV line disconnection conditions of 1.1 and 1.2, the fault characteristics are as follows: the three-phase voltage of the 110kV bus A, B, C of the load side transformer substation is asymmetrical, and the phase voltage of the broken line is-E A2 and about 0, 3U0is-3EA/2 or-EAWhile the amplitude and phase of the non-fault phase voltage do not change much, and in addition, the neutral point voltage U of the transformer0Are all-EA/2. There is a potential for breakdown of the transformer neutral.
Aiming at the situation, the invention provides a method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer.
The transmission and distribution network applied by the invention is a system network such as a 110kV single-bus subsection primary main connection (including a 110kV single-bus primary main connection), a 110kV inner bridging connection (shown in figure 7), a 110kV expansion inner bridging connection (shown in figure 8), a 110kV transformer bank connection (shown in figure 9) of a 110kV substation line and the like. Taking the primary main wiring of the 110kV single bus subsection of the 110kV substation as an example, the protection method of other primary main wirings is similar. The 110kV single-bus subsection primary main wiring structure of the 110kV substation is shown in fig. 6:
the No. 1 power supply incoming line branch equipment and the No. 2 power supply incoming line branch equipment are respectively connected with a 110kV I section bus and a 110kV II section bus; a segmented circuit breaker 3DL is arranged between the first segment bus and the second segment bus of 110kV, and is connected with a segmented current transformer CT in series; the No. 1 power supply inlet line branch circuit spacing equipment is a circuit breaker 1DL and is connected with a current transformer CT1 in series; the No. 2 power supply inlet wire branch circuit spacing device is a circuit breaker 2DL and is connected with a current transformer CT2 in series; the 110kV I-section bus is also connected with a No. 1 transformer branch, a No. 2 transformer branch, a No. 1 110kV outgoing line branch and a 110kV I-section bus voltage transformer PT 1; the 110kV II-section bus is also connected with a No. 3 transformer branch, a No. 2 110kV outgoing line branch and a 110kV II-section bus voltage transformer PT 2. No. 1 power inlet wire circuit power supply side is equipped with circuit breaker 4DL, and No. 2 power inlet wire circuit power supply side is equipped with circuit breaker 5 DL.
The 110kV neutral point operation mode of all main transformers on the I section or II section of buses of the load end 110kV substation is as follows: not grounded, grounded through the gap. The 110kV side is provided with a 110kV spare power automatic switching device.
Aiming at the primary main wiring of the 110kV single-bus subsection, a 110kV incoming line circuit breaker for measuring the 110kV neutral point voltage of a 110kV transformer and identifying the single-phase broken line and the broken line of a 110kV line is implemented in a load end 110kV substation, or a remote-jump 110kV line power supply side circuit breaker is started through 110kV line optical fiber current differential protection and matched with a backup power automatic switch to recover a relay protection scheme for supplying power to corresponding equipment so as to meet the field operation requirement. The protection method is implemented in a single 110kV line disconnection protection device of a load end 110kV substation, or a 110kV spare power automatic switching device, or a No. 1, No. 2 and No. 3 transformer protection device.
The method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer comprises the following steps:
method for identifying disconnection of each phase of 110kV line
Method for identifying each phase disconnection of No. 1.11 power supply incoming line circuit
Collecting a PT secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a first section of a bus of a 110kV transformer substation at a load end;
1) a-phase broken line identification method
(1) The voltage value of the PT secondary A phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary B phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is greater than the setting voltage value U3;
when the conditions are all met, a phase disconnection signal of a No. 1 110kV power supply incoming line circuit A is sent out after a delay of t 1;
2) method for identifying B-phase broken line
(1) The voltage value of the PT secondary B phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 1 110kV power incoming line B phase disconnection signal is sent out after the time delay of t 1;
3) c-phase broken line identification method
(1) The voltage value of the PT secondary C phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the voltage value of the PT secondary opening triangle of the I section of the bus is greater than a setting voltage value U3;
when the conditions are all met, a No. 1 110kV power supply incoming line C phase disconnection signal is sent out after time delay t 1;
method for identifying each phase disconnection of No. 1.22 power supply incoming line circuit
Collecting a secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a PT (potential transformer) of a II-section bus of a 110kV transformer substation at a load end;
1) a-phase broken line identification method
(1) The voltage value of a secondary A phase of a PT section II bus is smaller than a setting voltage value U1;
(2) the voltage value of the secondary B phase of the PT bus of the section II is between the upper limit and the lower limit of a setting voltage value U2;
(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 2 110kV power incoming line A phase disconnection signal is sent out after the time delay of t 1;
2) control method for B-phase broken line identification
(1) The voltage value of a secondary B phase of a PT section II bus is smaller than a setting voltage value U1;
(2) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 2 110kV line power supply incoming line B phase disconnection signal is sent out after time delay t 1;
3) control method for C-phase broken line identification
(1) The secondary C-phase voltage value of the II-section bus PT is smaller than a setting voltage value U1;
(2) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(4) the voltage value of the PT secondary opening triangle of the II section of bus is greater than a setting voltage value U3;
when the conditions are all met, a No. 2 110kV power incoming line C phase disconnection signal is sent out after a delay of t 1;
thirdly, judging the conditions of a 110kV line break starting trip circuit incoming line breaker and a 110kV spare power automatic switching standby power supply breaker:
2.1 judging condition of 1DL of No. 1 110kV line disconnection tripping 110kV No. 1 power supply incoming line circuit breaker 1DL or starting far tripping 110kV line power supply side circuit breaker 4DL through 110kV line optical fiber current differential protection, starting closing standby power supply circuit breaker 2DL or 3DL by 110kV backup power automatic switching
Collecting secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc and open triangular voltage 3Uo of a PT secondary A-phase voltage Ua of a first section of a bus PT of a load end 110kV transformer substation, and current of a CT at a 110kV neutral point gap of a No. 1 transformer and a No. 2 transformer,
condition 1:
the condition of a method for identifying the disconnection of each phase of a No. 1 110kV power supply incoming line circuit is met, the No. 1 110kV incoming line breaker 1DL is at a switching-on position, the 110kV neutral point voltage value of a No. 1 or No. 2 transformer is greater than a setting voltage value U4, after t2 delay, the load end transformer substation 110kV line incoming line breaker 1DL is tripped, the load end 110kV transformer substation 110kV spare power automatic switching action starts the 2DL or 3DL switching-on of a spare No. 2 110kV power supply breaker, and the transformer losing the power supply is recovered to the spare No. 2 110kV power supply to supply power; or the 1 # 110kV power line power supply side circuit breaker 4DL is tripped remotely by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection, and as the 1 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to trip the 1 # 110kV power supply incoming circuit breaker 1DL and closes the spare 2 # power supply circuit breaker 2DL or 3DL, so that the transformer losing power supply is recovered to the spare 2 # 110kV power supply for supplying power;
condition 2:
(1) the condition of each phase disconnection identification method of the No. 1 110kV power incoming line is met, and T time is opened; opening a primary pulse with T time, namely high level time;
(2) the zero sequence current 3Io of the neutral point of any main transformer on the bus is greater than a setting value I1;
when the conditions are all met and the No. 1 110kV incoming line breaker 1DL is in a switching-on position, after t3 is delayed, the No. 1 kV line incoming line breaker 1DL of the load end substation is tripped, and the No. 2 110kV power supply breaker 2DL or the No. 3kV spare power supply is started to switch on through the 110kV spare power automatic switching action of the load end substation, so that the transformer losing the power supply is recovered to the No. 2 spare 110kV power supply to supply power; or the 1 # 110kV power line power supply side circuit breaker 4DL is jumped far by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection, and as the 1 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to jump off the 1 # 110kV power supply incoming circuit breaker 1DL and closes the spare 2 # power supply circuit breaker 2DL or 3DL, so that the transformer losing power is recovered to the spare 2 # 110kV power supply for supplying power;
2.2 judge the condition of 2 # 110kV line break trip 110kV 2 power supply incoming line circuit breaker 2DL or starting the remote trip 110kV line power supply side breaker 5DL through 110kV line fiber current differential protection and the condition of 110kV backup power automatic switching starting closing backup power supply breaker 1DL or 3 DL:
collecting the current of PT secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc, open triangular voltage 3Uo and CT at 110kV neutral point gap of No. 3 transformer of load end 110kV transformer substation II section,
condition 1:
the condition of a method for identifying the disconnection of each phase of a No. 2 110kV power supply incoming line circuit is met, a No. 2 110kV incoming line breaker 2DL is at a switching-on position, the 110kV neutral point voltage value of a No. 3 transformer is greater than a setting voltage value U4, after t2 is delayed, the load-tripping end transformer substation 110kV line incoming breaker 2DL is started, the load-tripping end 110kV transformer substation 110kV spare power automatic switching action is used for starting the switching-on of a spare No. 1 110kV power supply breaker 1DL or 3DL, and the transformer losing the power supply is recovered to the spare No. 1 110kV power supply for power supply; or the 2 # 110kV power line power supply side circuit breaker 5DL is remotely tripped by starting the remote tripping function of the 2 # 110kV power line optical fiber differential protection, and as the 2 # 110kV power line loses power, the 110kV substation 110kV spare power automatic switching action at the load end starts to trip off the 2 # 110kV power incoming circuit breaker 2DL and closes the 1 # standby power circuit breaker 1DL or 3DL, so that the transformer losing power is recovered to the 1 # standby 110kV power supply for supplying power;
condition 2:
(1) the condition of the control method for identifying each phase disconnection of the No. 2 110kV power incoming line circuit meets the condition, and the T time is opened;
(2) the zero sequence current 3Io of the neutral point of any main transformer on the bus is greater than a setting value;
when the conditions are all met and the No. 2 110kV incoming line breaker 2DL is in the switching-on position, after time delay t3, tripping the No. 2kV line incoming line breaker 2DL of the load end transformer substation, starting the standby No. 1 110kV power supply breaker 1DL or 3DL to switch on by the 110kV backup power automatic switching action of the load end transformer substation, and enabling the transformer without the power supply to be recovered to the standby No. 1 110kV power supply to supply power; or the 2 # 110kV power line fiber differential protection remote tripping function is started, the 2 # 110kV power line power supply side circuit breaker 5DL is tripped remotely, and as the 2 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to trip the 2 # 110kV power incoming circuit breaker 2DL and closes the spare 12 # power circuit breaker 1DL or 3DL, so that the transformer losing power is recovered to the spare 1 # 110kV power supply for power supply.
After the 110kV line is judged to be broken, a load side or power supply side circuit breaker jumping the 110kV line is adopted, a load side substation 110kV side backup power automatic switch or a medium-low voltage side backup power automatic switch is used, a backup power supply circuit breaker is combined, and a bus or a transformer which runs in a phase failure due to the 110kV line breakage is adjusted to a backup line for power supply.
2.3 in 2.1 and 2.2 above,
(1) the reason why the condition 2 is adopted is that: once the 110kV neutral point gap of the transformer running on the bus is broken down, the condition 1 does not meet the starting condition and returns when the 110kV neutral point of the transformer is grounded, and the starting condition can be further optimized by adopting the condition 2;
(2) the reason that the 110kV power incoming line breaker 1DL or 2DL is adopted at the switching-on position is as follows: when a power supply incoming line is in a 110kV transformer substation with a load end, the bus voltage far away from the power supply incoming line can also sense the line disconnection information, and the standby power supply circuit breaker for closing of the standby automatic switching can be interfered; in addition, when a line PT is adopted, the power supply incoming line may have other load end 110kV substations, and if the power supply incoming line breaker of the load end 110kV substation trips slowly or refuses to trip, the power supply incoming line breaker of the backup power automatic switching device may also be interfered, and the backup power automatic switching device may not operate. The logic can be further optimized by adopting the condition that the 110kV power incoming line breaker is in the switching-on position.
(3) The reason for adopting the condition that the voltage of the 110kV neutral point of the measuring transformer exceeds the setting value is as follows: when the 110kV neutral point of the transformer is not grounded, the voltage of the 110kV neutral point of the transformer is Ea/2 under the conditions that the 110kV line is broken or the 110kV line is broken and the load side at the broken line is grounded.
3. The 110kV neutral point operation mode of the main transformer on the I section or II section of the bus of the load end 110kV substation is as follows: not grounded, grounded through the gap. A110 kV spare power automatic switching device is arranged on the 110kV side of a 110kV substation. When a circuit breaker on the power supply side of a broken line is subjected to long jump, the No. 1 and No. 2 power supply 110kV lines are required to be provided with an optical fiber channel and line optical fiber differential protection.
4. The method can be implemented in a single 110kV line disconnection protection device of a load end 110kV substation, or in a 110kV line protection device or a 110kV spare power automatic switching device, or in a No. 1, No. 2 or No. 3 transformer protection device; when the method is implemented in a 110kV spare power automatic switching device, new hardware interfaces such as 3UO and 3Io are required to be added; the protection device is implemented in the No. 1, No. 2 and No. 3 transformer protection devices, and does not need to add hardware equipment.
5. The setting values of all voltages of the 110kV line of the load end 110kV substation are as follows:
(1) the secondary voltage setting value of the disconnection phase PT is 1.3-1.5 times of the highest voltage value possible during disconnection, and the highest voltage value 29V of the phase rated voltage value of 1/2 is taken as + 10%, namely the value range of the setting voltage value U1 is 42V-48V; for example, 45V may be used.
(2) The non-broken line phase PT secondary voltage setting value U2 is as follows: the phase rated voltage value is +/-10% (58V +/-10%), namely between 52.2 and 63.8V;
(3) the voltage setting value of the bus PT secondary opening triangle is as follows: the lowest possible voltage value is 100V when the wire is broken, and a sensitivity coefficient of 1.3-1.5 is taken, namely, the value is taken within the range of 67V-77V, for example, 70V can be taken.
(4) Setting value U4 of transformer 110kV neutral point voltage Uo: 1/2, the phase rated voltage value is 29V, the sensitivity coefficient is 1.3-1.5, namely the value is within the range of 19V-22V, for example 20V.
6. The setting values of time and current in the relay protection method for identifying the single-phase disconnection of the 110kV line and matching with the spare power automatic switching device are as follows:
(1) time t 1: avoiding the single-phase grounding relay protection action process time, and setting the time to be 2-4 seconds;
(2) setting the t2 time to be 0.15-0.5 seconds;
(3) setting the t3 time to be 0.15-0.5 seconds;
(4) the opening T time is set to be 5-7 seconds;
(5) the zero sequence current 3Io setting value I1 of the 110kV neutral point of the main transformer is set to be 40-100A.
7. When the 110kV transformer substation adopts primary main wiring of a 110kV line transformer group, the spare power automatic switching device on the middle and low voltage sides of the transformer substation on the load side completes the task of power restoration.
8. The inventive solution can be used in the following cases: (1) the 110kV neutral point operation mode of all transformers of a load end 110kV transformer substation is as follows: not grounded, grounded through the gap; (2) the 110kV side of the 110kV transformer substation is provided with a spare power automatic switching device, or the middle and low voltage sides are provided with spare power automatic switching devices; (3) when a circuit breaker on the power supply side of a broken line is subjected to long jump, the No. 1 and No. 2 power supply 110kV lines are required to be provided with an optical fiber channel and line optical fiber differential protection.
And can satisfy the following primary main wiring: (1) a 110kV single-bus subsection primary main wiring of a 110kV transformer substation; (2) a 110kV transformer substation 110kV inner bridge primary main wiring; (3) a 110kV substation 110kV primary main wiring is enlarged; (4)110kV transformer substation 110kV line group primary main wiring; (5) other primary main connections.
9. The scheme of the invention can also be used in the case of the disconnection of a 220kV line powered by a single power supply.
An embodiment of the method of the present invention is given below (taking fig. 6 and starting a trip load side substation 110kV line breaker as an example):
1 operating mode 1
Under this operational mode, 2DL of No. 2 power circuit breaker, the operation of segmentation circuit breaker 3DL, 1DL of No. 1 power circuit breaker is hot standby, 1DL of No. 1 power circuit breaker branch floodgate position promptly.
No. 1.12 110kV power line single-phase line break fault
For example, if phase A is broken, phase B or phase C is broken similarly. When the A phase single-phase disconnection fault of the No. 2 110kV power line occurs, the method is equivalent to pulling a disconnecting switch with load, an electric arc is generated at the disconnection moment, the electric arc cannot be extinguished, the electric arc is further developed to cause the A phase single-phase grounding of the line, and the protection starting action of the distance I section or the section II of the superior No. 2 power line jumps from a power side circuit breaker 5DL of the superior No. 2kV power line within the protection range of the distance I section or the section II of the superior No. 2 power line; after a first section or a second section of a bus of a load end 110kV power substation loses power, a phase A disconnection fault of a No. 2 110kV power line disappears, a circuit breaker 5DL on the power side of a superior No. 2kV power line is successfully superposed in a delayed mode, but the first section or the second section of the bus of the load end substation experiences open-phase operation, PT secondary voltage of the second section of the bus meets the condition 1 for identifying the single-phase disconnection of the No. 2kV power line, the phase A single-phase disconnection fault of the No. 2kV power line is sent out through delayed t1, the 110kV neutral point voltage value of the No. 2 transformer meets the condition, after the delay of t2, a No. 2 110kV power incoming circuit breaker 2DL of a No. 2kV power supply of a load tripping end 110kV power substation is started, and the No. 1 kV backup power supply circuit breaker 1DL is switched on by a 110kV backup power switch, and the No. 1, 2 and No. 3 transformers losing power are.
The T time is opened because the above condition 1 is satisfied; if the time t2 does not reach, the 110kV neutral point of the No. 1 or No. 2 main transformer breaks down, the generated zero sequence current exceeds a setting value, the No. 2kV line incoming circuit breaker 2DL of the load tripping end power transformation No. 2kV line is started after the time t3 is delayed, the No. 1 kV standby power supply circuit breaker is started by the 110kV spare power automatic switch, and the No. 1, No. 2 and No. 3 transformers losing the power supply are recovered to the standby No. 1 kV line for power supply.
2 operating mode 2
Under this operational mode, 1DL of power breaker, 3DL operation of section circuit breaker, 2 # power breaker 2DL are hot standby, 2 # power breaker 2DL separating brake position promptly.
No. 2.11 110kV power line single-phase line break fault
For example, if phase A is broken, phase B or phase C is broken similarly. When the A phase single-phase line break fault of the No. 1 110kV power line occurs, the method is equivalent to pulling a disconnecting switch with load, electric arcs are generated at the line break moment, the electric arcs cannot be extinguished, the electric arcs further cause the A phase single-phase grounding of the line, and the protection starting action of the No. 1 power line at the section I or the section II of the distance between the No. 1 power line at the upper level jumps away from a circuit breaker 4DL at the power supply side of the No. 1 power line at the upper level because the distance between the No. 1 power line at the upper level and the section I or the; after a load end 110kV substation loses power, the fault of the phase A disconnection position of a 110kV power line 1 disappears, the circuit breaker 4DL on the power side of the 110kV power line 1 is successfully superposed, but the voltage of a section I bus of the load end 110kV substation is subjected to phase-loss operation, the secondary voltage of the section I bus PT meets the condition 1 for identifying the single-phase disconnection of the 110kV power line 1, the phase A single-phase disconnection fault of the 110kV power line 1 is sent out through time delay t1, the voltage value of a 110kV neutral point of a transformer 1 meets the condition, after time delay of t2, the phase A incoming circuit breaker 1DL of the 110kV power line 1 of the load tripping end 110kV substation is started, the phase A single-phase disconnection fault of the 110kV backup power line 2 is started through 110kV backup power automatic switching, and the phase B110 kV backup power circuit breaker 2DL of the transformer 1, the phase B and the phase B3 of the power line 2 is switched.
The T time is opened because the above condition 1 is satisfied; if the time of t2 does not reach, the 110kV neutral point of the No. 3 main transformer is broken down, the generated zero sequence current exceeds a setting value, after t3 time delay, the No. 1 110kV power supply incoming line circuit breaker 1DL of the 110kV transformer substation at the load tripping end is started, the No. 2kV standby power supply circuit breaker 2DL is started by 110kV spare power automatic switching, and the No. 1, No. 2 and No. 3 transformers losing power supplies power are recovered to the No. 2 110kV standby power supply circuit for power supply.
3 operating mode 3
Under this operational mode, 1DL of No. 1 power circuit breaker, 2DL of No. 2 power circuit breaker operate, and the hot reserve of section circuit breaker 3DL, section circuit breaker 3DL separating brake position promptly.
No. 3.11 110kV power line single-phase line break fault
For example, if phase A is broken, phase B or phase C is broken similarly. When the A phase single-phase disconnection fault of the No. 1 110kV power line occurs, the method is equivalent to pulling the isolating switch with load, electric arcs are generated at the disconnection moment, the electric arcs cannot be extinguished, the electric arcs further cause the A phase single-phase grounding of the line, and the protection starting action of the No. 1 superior 110kV power line is tripped out of a power supply side circuit breaker 4DL of the No. 1 superior power line within the protection range of the No. 1 superior power line from the No. 1 superior power; after a load end substation loses power, a 110kV power supply line A phase disconnection fault disappears, a 1 # 110kV power supply line power side circuit breaker 4DL is successfully superposed, but a 1 # 110kV power supply line A phase disconnection fault of the load end 110kV substation is sent out through time delay t1, 110kV neutral point voltage value of a 1 # transformer meets conditions, a 1 # 110kV power supply line incoming circuit breaker 1DL of a load tripping end substation is started after time delay of t2, and a 110kV backup power supply circuit breaker 3DL is started to be switched on, so that a 1 # transformer and a 2 # transformer of a power supply are recovered to a 2 # 110kV backup power supply line for power supply.
The T time is opened because the above condition 1 is satisfied; if the time t2 does not reach, the 110kV neutral point of the No. 1 or No. 2 main transformer is broken down, the generated zero sequence current exceeds a setting value, the No. 1 110kV power incoming line circuit breaker 1DL of the load tripping end transformer substation is started after the time delay t3, the 110kV backup power circuit breaker 3DL is started by the 110kV backup automatic switch, and the No. 1 and No. 2 transformers losing the power supply are recovered to the backup No. 2 110kV power line for power supply.
No. 3.22 110kV power line single-phase line break fault
For example, if phase A is broken, phase B or phase C is broken similarly. When the phase-A single-phase disconnection fault of the No. 2 110kV power line occurs, the method is equivalent to pulling the isolating switch with load, electric arcs are generated at the disconnection moment, the electric arcs cannot be extinguished, the electric arcs further cause the phase-A single-phase grounding of the line, and the protection starting action of the section I or the section II of the distance between the upper level No. 2kV power line and the upper level No. 2 power line jumps away from the circuit breaker 5DL at the power supply side of the upper level No. 2 power line because the distance between the upper level No. 2kV power line and the section I or the; after a 110kV II section bus of a load end 110kV substation loses power, a fault at the phase A disconnection position of a 110kV power line disappears, a circuit breaker 5DL at the power side of the 110kV power line is successfully superposed through time delay 2, but voltage inductance of the II section bus of the load end 110kV substation is in open-phase operation, PT secondary voltage of the II section bus meets the condition 1 for identifying 110kV line single-phase disconnection, the phase A single-phase disconnection fault of the 2 # 110kV power line is sent out through time delay t1, the voltage value of a 110kV neutral point of a No. 2 transformer meets the condition, after time delay of t2, a transformer substation incoming line breaker 1DL at the tripping end 1 # 110kV power line is started, a 110kV backup power circuit breaker 3DL is started through 110kV backup automatic switching, and the No. 3 transformer losing the power is recovered to a backup No. 2kV 110kV power line for power supply.
The T time is opened because the above condition 1 is satisfied; if the time t2 does not reach, the 110kV neutral point of the No. 3 main transformer is broken down, the generated zero sequence current exceeds a setting value, after the time delay t3, the No. 1 110kV power supply incoming line circuit breaker 1DL of the load tripping end transformer substation is started, the 110kV standby power supply circuit breaker 3DL is started by the 110kV backup power automatic switch, and the No. 3 transformer losing the power supply is recovered to the standby No. 2 110kV power supply line for power supply.
In addition to the above embodiments, the present invention may have other embodiments, and any technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of the claims of the present invention.

Claims (4)

1. A method for measuring 110kV line disconnection relay protection of neutral point voltage of a transformer is characterized by comprising the following steps:
method for identifying disconnection of each phase of 110kV line
Method for identifying each phase disconnection of No. 1.11 power supply incoming line circuit
Collecting a PT secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a first section of a bus of a 110kV transformer substation at a load end;
1) a-phase broken line identification method
(1) The voltage value of the PT secondary A phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary B phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is greater than the setting voltage value U3;
when the conditions are all met, a phase disconnection signal of a No. 1 110kV power supply incoming line circuit A is sent out after a delay of t 1;
2) method for identifying B-phase broken line
(1) The voltage value of the PT secondary B phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 1 110kV power incoming line B phase disconnection signal is sent out after the time delay of t 1;
3) c-phase broken line identification method
(1) The voltage value of the PT secondary C phase of the I section bus is smaller than a setting voltage value U1;
(2) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the voltage value of the PT secondary opening triangle of the I section of the bus is greater than a setting voltage value U3;
when the conditions are all met, a No. 1 110kV power supply incoming line C phase disconnection signal is sent out after time delay t 1;
method for identifying each phase disconnection of No. 1.22 power supply incoming line circuit
Collecting a secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a PT (potential transformer) of a II-section bus of a 110kV transformer substation at a load end;
1) a-phase broken line identification method
(1) The voltage value of a secondary A phase of a PT section II bus is smaller than a setting voltage value U1;
(2) the voltage value of the secondary B phase of the PT bus of the section II is between the upper limit and the lower limit of a setting voltage value U2;
(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 2 110kV power incoming line A phase disconnection signal is sent out after the time delay of t 1;
2) method for identifying B-phase broken line
(1) The voltage value of a secondary B phase of a PT section II bus is smaller than a setting voltage value U1;
(2) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(3) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;
(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is greater than the setting voltage value U3;
when the conditions are all met, a No. 2 110kV line power supply incoming line B phase disconnection signal is sent out after time delay t 1;
3) c-phase broken line identification method
(1) The secondary C-phase voltage value of the II-section bus PT is smaller than a setting voltage value U1;
(2) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;
(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;
(4) the voltage value of the PT secondary opening triangle of the II section of bus is greater than a setting voltage value U3;
when the conditions are all met, a No. 2 110kV power incoming line C phase disconnection signal is sent out after a delay of t 1;
judging the conditions of a 110kV line disconnection starting trip circuit incoming line breaker and a 110kV backup power automatic switching standby power supply breaker:
2.1 judging condition of 1DL of No. 1 110kV line disconnection tripping 110kV No. 1 power supply incoming line circuit breaker 1DL or starting far tripping 110kV line power supply side circuit breaker 4DL through 110kV line optical fiber current differential protection, starting closing standby power supply circuit breaker 2DL or 3DL by 110kV backup power automatic switching
Collecting secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc and open triangular voltage 3Uo of a PT secondary A-phase voltage Ua of a first section of a bus PT of a load end 110kV transformer substation, and current of a CT at a 110kV neutral point gap of a No. 1 transformer and a No. 2 transformer,
condition 1:
the condition of a method for identifying the disconnection of each phase of a No. 1 110kV power supply incoming line circuit is met, the No. 1 110kV incoming line breaker 1DL is at a switching-on position, the 110kV neutral point voltage value of a No. 1 or No. 2 transformer is greater than a setting voltage value U4, after t2 delay, the load end transformer substation 110kV line incoming line breaker 1DL is tripped, the load end 110kV transformer substation 110kV spare power automatic switching action starts the 2DL or 3DL switching-on of a spare No. 2 110kV power supply breaker, and the transformer losing the power supply is recovered to the spare No. 2 110kV power supply to supply power; or the 1 # 110kV power line power supply side circuit breaker 4DL is tripped remotely by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection, and as the 1 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to trip the 1 # 110kV power supply incoming circuit breaker 1DL and closes the spare 2 # power supply circuit breaker 2DL or 3DL, so that the transformer losing power supply is recovered to the spare 2 # 110kV power supply for supplying power;
condition 2:
(1) the condition of each phase disconnection identification method of the No. 1 110kV power incoming line is met, and T time is opened; opening a primary pulse with T time, namely high level time;
(2) the zero sequence current 3Io of the neutral point of any main transformer on the bus is greater than a setting value I1;
when the conditions are all met and the No. 1 110kV incoming line breaker 1DL is in a switching-on position, after t3 is delayed, the No. 1 kV line incoming line breaker 1DL of the load end substation is tripped, and the No. 2 110kV power supply breaker 2DL or the No. 3kV spare power supply is started to switch on through the 110kV spare power automatic switching action of the load end substation, so that the transformer losing the power supply is recovered to the No. 2 spare 110kV power supply to supply power; or the 1 # 110kV power line power supply side circuit breaker 4DL is jumped far by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection, and as the 1 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to jump off the 1 # 110kV power supply incoming circuit breaker 1DL and closes the spare 2 # power supply circuit breaker 2DL or 3DL, so that the transformer losing power is recovered to the spare 2 # 110kV power supply for supplying power;
2.2 judge the condition of 2 # 110kV line break trip 110kV 2 power supply incoming line circuit breaker 2DL or starting the remote trip 110kV line power supply side breaker 5DL through 110kV line fiber current differential protection and the condition of 110kV backup power automatic switching starting closing backup power supply breaker 1DL or 3 DL:
collecting the current of PT secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc, open triangular voltage 3Uo and CT at 110kV neutral point gap of No. 3 transformer of load end 110kV transformer substation II section,
condition 1:
the condition of a method for identifying the disconnection of each phase of a No. 2 110kV power supply incoming line circuit is met, a No. 2 110kV incoming line breaker 2DL is at a switching-on position, the 110kV neutral point voltage value of a No. 3 transformer is greater than a setting voltage value U4, after t2 is delayed, the load-tripping end transformer substation 110kV line incoming breaker 2DL is started, the load-tripping end 110kV transformer substation 110kV spare power automatic switching action is used for starting the switching-on of a spare No. 1 110kV power supply breaker 1DL or 3DL, and the transformer losing the power supply is recovered to the spare No. 1 110kV power supply for power supply; or the 2 # 110kV power line power supply side circuit breaker 5DL is remotely tripped by starting the remote tripping function of the 2 # 110kV power line optical fiber differential protection, and as the 2 # 110kV power line loses power, the 110kV substation 110kV spare power automatic switching action at the load end starts to trip off the 2 # 110kV power incoming circuit breaker 2DL and closes the 1 # standby power circuit breaker 1DL or 3DL, so that the transformer losing power is recovered to the 1 # standby 110kV power supply for supplying power;
condition 2:
(1) the condition of each phase disconnection identification method of the No. 2 110kV power incoming line is met, and T time is opened;
(2) the zero sequence current 3Io of the neutral point of any main transformer on the bus is greater than a setting value;
when the conditions are all met and the No. 2 110kV incoming line breaker 2DL is in the switching-on position, after time delay t3, tripping the No. 2kV line incoming line breaker 2DL of the load end transformer substation, starting the standby No. 1 110kV power supply breaker 1DL or 3DL to switch on by the 110kV backup power automatic switching action of the load end transformer substation, and enabling the transformer without the power supply to be recovered to the standby No. 1 110kV power supply to supply power; or the 2 # 110kV power line fiber differential protection remote tripping function is started, the 2 # 110kV power line power supply side circuit breaker 5DL is tripped remotely, and as the 2 # 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching action starts to trip the 2 # 110kV power incoming circuit breaker 2DL and closes the 1 # standby power circuit breaker 1DL or 3DL, so that the transformer losing power is recovered to the 1 # standby 110kV power supply for power supply.
2. The method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer as claimed in claim 1, wherein the setting voltage value U1 is 1.3-1.5 times of the highest voltage value possible during disconnection, namely the setting voltage value U1 has a value range of 42V-48V;
the upper limit value of the setting voltage value U2 is 63.8V, and the lower limit value is 52.2V;
the setting voltage value U3 is: taking a sensitivity coefficient of 1.3-1.5 according to the lowest possible voltage value of 100V when the line is broken, namely taking a value in the range of 67V-77V;
the setting voltage value U4 is: and taking a sensitivity coefficient of 1.3-1.5 according to the phase rated voltage value of 1/2V, namely taking a value in the range of 19V-22V.
3. The method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer according to claim 1, wherein the t1 time is set to be 2-4 seconds; setting the t2 time to be 0.15-0.5 seconds; setting the t3 time to be 0.15-0.5 seconds; the opening T time is set to be 5-7 seconds; the setting value range of zero sequence current 3Io of the 110kV neutral point of the main transformer is 40-100A.
4. The method for measuring the 110kV line disconnection relay protection of the neutral point voltage of the transformer according to claim 1, wherein after the 110kV line is judged to be disconnected, a load side or power side breaker for tripping the 110kV line is adopted, a load side substation 110kV side backup power automatic switch or a medium-low voltage side backup power automatic switch is adopted, a backup power supply breaker is closed, and a bus or a transformer which runs in a phase failure due to the disconnection of the 110kV line is adjusted to a backup line for power supply.
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CN113625189B (en) * 2021-08-02 2022-09-02 国网江苏省电力有限公司镇江供电分公司 110kV line disconnection protection method for measuring low-voltage side phase voltage of transformer
CN113629671B (en) * 2021-08-02 2022-09-30 国网江苏省电力有限公司镇江供电分公司 110kV line disconnection protection method for measuring low-voltage lateral line voltage of transformer

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