CN110880744B

CN110880744B - Line disconnection protection method for comparing voltage amplitude difference of two side lines of line

Info

Publication number: CN110880744B
Application number: CN201911247150.1A
Authority: CN
Inventors: 刘昶; 胡浩; 汤勋; 孙东杰; 杨静; 朱文韬; 姜正驰; 杜炜凝; 戴星宇
Original assignee: State Grid Jiangsu Electric Power Co ltd Zhenjiang Power Supply Branch
Current assignee: State Grid Jiangsu Electric Power Co ltd Zhenjiang Power Supply Branch
Priority date: 2019-12-09
Filing date: 2019-12-09
Publication date: 2021-02-19
Anticipated expiration: 2039-12-09
Also published as: CN110880744A

Abstract

The invention discloses a line disconnection protection method for comparing voltage amplitude differences of two side lines of a line. The invention adopts a relay protection scheme that voltage information at two sides of the line is transmitted through the optical fiber channel of the line, the line voltage amplitude difference at two sides of the line is compared to identify line disconnection, and a load end transformer substation transfers load power supply by adopting a loop closing and opening operation, so that a transformer losing a power supply recovers to a standby power supply for supplying power, thereby effectively preventing the influence of the transformer on the power grid and the load power supply due to phase failure power supply and being beneficial to the safe and stable operation of the power grid.

Description

Line disconnection protection method for comparing voltage amplitude difference of two side lines of line

Technical Field

The invention relates to a line disconnection protection method for comparing voltage amplitude differences of two side lines of a line, and belongs to the technical field of protection and control of an electric power transmission and distribution network.

Background

At present, the line disconnection phenomenon of 3-66 kV (including 3, 6, 10, 20, 35 and 66kV) lines occurs in power grids in various places, and the line disconnection causes the phase-loss operation of a transformer supplied by the lines, so that the three-phase voltage of the transformer is asymmetric, the influence is generated on load power supply, electrical equipment can be damaged, for example, a motor is damaged due to the phase-loss operation. In the prior art, no relay protection device and method specially aiming at the disconnection of a 3-66 kV line exist. The invention provides a single-phase line-breaking relay protection method which is characterized in that voltage information on two sides of a line is transmitted through a line optical fiber channel at a load-end substation, the line voltage amplitude difference of the two sides of the line is compared to identify the line breaking of a 3-66 kV line, and the load-end substation transfers load power supply by adopting ring closing and opening operation.

Disclosure of Invention

The invention aims to provide a line disconnection protection method for comparing voltage amplitude differences of two side lines of a line, which is used for a load end 3-66 kV transformer substation, voltage information of the two sides of the line is transmitted through a line optical fiber channel, line voltage amplitude differences of the two sides of the line are compared to identify line disconnection, and the load end 3-66 kV transformer substation adopts a single-phase disconnection relay protection method for transferring load power supply by adopting a closed-loop operation.

The purpose of the invention is realized by the following technical scheme:

a line disconnection protection method for comparing voltage amplitude differences of two side lines of a line comprises the following steps:

judging the condition of tripping on the incoming line breaker after the line is broken and the load end substation standby breaker is closed

1.1, judging the 1 # line disconnection, after t1 delay time, closing the condition of the load end substation standby circuit breaker 2DL or 3DL and tripping the 1 # line load side circuit breaker 1DL, and starting the 1 # line disconnection alarm condition:

collecting power supply side bus PT secondary AB line voltage value U_A1B1BC line voltage value U_B1C1CA line voltage value U_C1A1No. 1 line power supply side circuit breaker 4DL switching-on position information, load end I section bus PT secondary AB line voltage value U of transformer substation_A2B2BC line voltage value U_B2C2CA line voltage value U_C2A21DL switching-on position information of the No. 1 line load side circuit breaker; sending the signals to disconnection protection in the load side transformer substation line protection of the No. 1 line;

conditions are as follows: (1) in No. 1 circuit, the voltage value U of the secondary AB line of the power supply side bus PT_A1B1Absolute value and load end transformer substation I section bus PT secondary AB line voltage value U_A2B2Difference of absolute value, secondary BC line voltage value U of power side bus PT_B1C1Absolute value and load end transformer substation I section bus PT secondary BC line voltage value U_B2C2Difference of absolute value of, power side bus PT twosub-CA line voltage value U_C1A1Absolute value and load end transformer substation I section bus PT secondary CA line voltage value U_C2A2Of the three differences, two differences being 0.38E_abTo 0.55E_abA difference of 0.1E or less_ab；E_abThe voltage value of a secondary side rated line of a power supply PT;

(2) power supply end corresponding bus PT secondary AB line voltage value U_A1B1Greater than or equal to 0.9E_ab1.1E or less_ab；

(3) Power supply end corresponding bus PT secondary BC line voltage value U_B1C1Greater than or equal to 0.9E_ab1.1E or less_ab；

(4) Power supply end corresponding bus PT secondary CA line voltage value U_C1A1Greater than or equal to 0.9E_ab1.1E or less_ab；

(5) The power supply end line breaker 4DL of the line 1 is at the switching-on position;

(6) the 1 st line load side breaker 1DL is in the on position;

if the conditions are all met, the No. 1 power supply circuit is identified and judged to be broken, after t1 delay time, the broken line protection action in the No. 1 circuit protection of the load-side substation starts, and after the standby power supply circuit breaker 2DL or 3DL is closed, the No. 1 circuit load-side circuit breaker 1DL is tripped, so that the transformer without the power supply is recovered to the standby power supply circuit for power supply. Simultaneously starting No. 1 line disconnection alarm;

1.2 judge No. 2 circuit broken string, after t1 delay time, close load end transformer substation stand-by power supply circuit breaker 1DL or 3DL and jump off No. 2 inlet wire circuit breaker 2 DL's condition to start No. 2 circuit broken string and report to the police the condition:

collecting power supply side bus PT secondary AB line voltage value U_A1B1BC line voltage value U_B1C1CA line voltage value U_C1A1No. 2 line power supply side circuit breaker 5DL switching-on position information, load end I section bus PT secondary AB line voltage value U of transformer substation_A2B2BC line voltage value U_B2C2CA line voltage value U_C2A2And 2, the 2DL switching-on position information of the circuit breaker on the load side of the power inlet line is sent to the 2In the line protection of the load side substation line of the line, the disconnection protection is performed.

Conditions are as follows: (1) in No. 2 circuit, the voltage value U of secondary AB line of power supply side bus PT_A1B1Absolute value and load end transformer substation I section bus PT secondary AB line voltage value U_A2B2Difference of absolute value, secondary BC line voltage value U of power side bus PT_B1C1Absolute value and load end transformer substation I section bus PT secondary BC line voltage value U_B2C2Difference of absolute value, power source side bus PT secondary CA line voltage value U_C1A1Absolute value and load end transformer substation I section bus PT secondary CA line voltage value U_C2A2Of the three differences, two differences being 0.38E_abTo 0.55E_abA difference of 0.1E or less_ab；E_abThe voltage value of a secondary side rated line of a power supply PT;

(5) The power supply end circuit breaker 5DL of the No. 2 circuit is at the switching-on position;

(6) the load side line breaker 2DL of line No. 2 is in the on position;

if the conditions are all met, identifying and judging that the No. 2 power supply circuit is disconnected, after t1 delay time, performing disconnection protection action in the No. 2 circuit protection of the load-side substation, and after switching on the standby power supply circuit breaker 1DL or 3DL, tripping off the No. 2 power supply circuit load-side circuit breaker 2DL to enable the transformer without the power supply to recover to the standby power supply circuit for power supply; and simultaneously, starting No. 2 line disconnection alarm.

The object of the invention can be further achieved by the following technical measures:

the line disconnection protection method for comparing the voltage amplitude difference of the two side lines of the line is applied to the mode that the neutral point of the transformer is not grounded or is grounded through an arc suppression coil or is grounded through a small resistor.

The line disconnection protection method for comparing the voltage amplitude difference between two sides of the line, the power supply PT secondary side rated line voltage value E_abIs 100V.

According to the line disconnection protection method for comparing the voltage amplitude difference of the two side lines of the line, the delay time of t1 is 0.1-0.2 second when the three phases are not in phase when the breaker is switched on.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention fully utilizes the fault characteristics of the secondary voltage of the bus PT of the power supply end and the load end transformer substation when the single-phase line is broken, compares the voltage amplitude difference of the buses at the two ends of the line, identifies the single-phase line break of the line, and transfers the load power supply by the load end transformer substation through the ring closing and opening operation, thus being simple and easy.

2. The invention adopts a relay protection scheme that voltage information at two sides of the line is transmitted through the optical fiber channel of the line, the line voltage amplitude difference at two sides of the line is compared to identify line disconnection, and a load end transformer substation transfers load power supply by adopting a loop closing and opening operation, so that a transformer losing a power supply recovers to a standby power supply for supplying power, thereby effectively preventing the influence of the transformer on the power grid and the load power supply due to phase failure power supply and being beneficial to the safe and stable operation of the power grid.

3. The method of the invention is implemented by adopting the line protection devices at two sides of the line, and does not need to increase hardware equipment.

Drawings

FIG. 1 is a schematic diagram of a primary system of a superior substation with 35kV side not grounded or grounded through an arc suppression coil;

FIG. 2 is a vector diagram of the voltage of a 35kV bus on the power supply side without grounding or through arc suppression coils;

FIG. 3 is a vector diagram of the voltage of a 35kV bus on the load side without grounding or through an arc suppression coil;

FIG. 4 is a schematic diagram of a primary system with a 35kV line break and a load side line break grounded;

FIG. 5 is a vector diagram of the voltage of a 35kV bus on the load side at a load side disconnection point;

FIG. 6 is a schematic diagram of a primary system with a 35kV line broken and a power supply side grounded;

FIG. 7 is a vector diagram of the voltage of a 35kV bus at the ground power supply side at a power supply side disconnection;

FIG. 8 is a vector diagram of the voltage of a 35kV bus at the grounded load side at the power supply side disconnection;

fig. 9 is a schematic diagram of a primary system of a superior substation with 35kV side grounded through a resistor;

FIG. 10 is a vector diagram of 35kV bus voltage at the 35kV side of the upper-level substation via the resistance grounding power supply side;

fig. 11 is a voltage vector diagram of a 35kV bus at a 35kV side of an upper-level substation through a resistance grounding load side;

FIG. 12 is a schematic diagram of a primary system with a 35kV line break and a load side line break grounded;

FIG. 13 is a vector diagram of the voltage of a 35kV bus at the load side which is grounded at a load side disconnection;

FIG. 14 is a schematic diagram of a 35kV primary system with a power supply side disconnected and a ground connection;

FIG. 15 is a schematic diagram of the disconnection protection of the present invention;

FIG. 16 is a primary main wiring diagram of a single bus segment of a 35kV substation;

FIG. 17 is a primary main wiring diagram of an inner bridge of a 35kV substation;

FIG. 18 is a primary main wiring diagram of an enlarged inner bridge of a 35kV substation;

fig. 19 is a primary main connection of a 35kV line transformer set of a 35kV substation.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

Firstly, analyzing fault characteristics by taking 35kV line breakage as an example:

1.1 ungrounded or arc-suppression coil grounding system

1.1.135kV line broken wire

Fig. 1 is a schematic diagram of a 35kV primary disconnection system, taking an a-phase stub as an example. The 35kV side of the upper-level transformer substation is not grounded or is grounded through an arc suppression coil, and the 35kV neutral point of the 35kV transformer substation on the load side is not grounded. The power supply potentials at 35kV sides of the upper-level transformer substation are respectively set as E_A、E_B、E_C，U_NIf alpha is broken for the 35kV neutral point voltage of the transformer of the power side transformer substation, the capacitance to ground of the bus side of the transformer substation from the broken line to the upper level is alpha C, and the capacitance to ground of the 35kV bus of the transformer substation from the broken line to the load side is (1-alpha) C.

1. Power supply side bus voltage analysis

Analyzing to obtain the voltage of a bus at the 35kV side of the upper-level transformer substation as follows:

(1) in the formula (I), the compound is shown in the specification,

the voltage of a power side 35kV bus A1B1 line, the voltage of a B1C1 line and the voltage of a C1A1 line are respectively. ,

the voltage of the 35kV side power line of the upper-level transformer substation is equal. The vector diagram of the voltage of the 35kV bus on the power supply side is shown in fig. 2, and as can be seen from fig. 2, when the phase A of the 35kV line is disconnected, the voltage of the three-phase line of the 35kV bus of the upper-level substation is unchanged and keeps symmetry. In the figure, alpha varies between 0 and 1, and 0 point is 0 in FIG. 2_α＝0To 0_α＝1When α is 1, point 0 is 0_α＝1At the point, when α is 0, 0 is 0_α＝0(the same applies below).

2. Load side bus voltage analysis

The 35kV load side bus voltage is analyzed as follows:

(2) in the formula (I), the compound is shown in the specification,

the line voltage of the load side 35kV bus A2B2, the line voltage of B2C2 and the line voltage of C2A2 are shown in a vector diagram of the load side 35kV bus in figure 3.

As can be seen from FIG. 3, when the 35kV line is disconnected, the load side

Is composed of

And

in the opposite direction and of magnitude

1.1.235kV line disconnection and load side disconnection grounding

Fig. 4 is a schematic diagram of a 35kV line break and load side line break grounding primary system, taking an a-phase stub as an example. The 35kV side of the upper-level transformer substation is not grounded, and the 35kV neutral point of the 35kV transformer substation on the load side is not grounded. The power supply potentials at 35kV sides of the upper-level transformer substation are respectively set as E_A、E_B、E_C，U_NThe voltage of a 35kV neutral point of a transformer substation on a power supply side is alpha C on the bus side of a transformer substation from a broken line to a superior substation, and the capacitance of the 35kV bus of the transformer substation from the broken line to a load side is (1-alpha) C.

1. Power supply side bus voltage analysis

The analysis was as in 1.1.1.

2. Load side bus voltage analysis

The 35kV load side bus voltage is analyzed as follows:

the vector diagram of the 35kV bus voltage on the load side is shown in figure 5.

As can be seen from FIG. 5, when the 35kV line is broken and the load side broken line is grounded,

is equal to

Along with the difference of the distance of the broken line close to the power supply side bus, alpha varies between 0 and 1, and simultaneously

In that

To a change of 0, point 0 being as in FIG. 5 0_α＝0To 0_α＝1The number of the intermediate change is changed,

is as large as

Change to E_BWhile varying between

Size of (2)

Change to E_CAnd (4) change.

1.1.335 kV line disconnection and power supply side disconnection point grounding

Fig. 6 is a schematic diagram of a primary system with a 35kV line broken and a power supply side grounded, taking an a-phase short line as an example. The 35kV side of the upper-level transformer substation is not grounded, and the 35kV neutral point of the 35kV transformer substation on the load side is not grounded. The power supply potentials at 35kV sides of the upper-level transformer substation are respectively set as E_A、E_B、E_C，U_NThe voltage of a 35kV neutral point of a transformer substation on a power supply side is alpha C on the bus side of a transformer substation from a broken line to a superior substation, and the capacitance of the 35kV bus of the transformer substation from the broken line to a load side is (1-alpha) C.

1. Power supply side bus voltage analysis

Analyzing the voltage of a bus at the 35kV side of the upper-level transformer substation:

the vector diagram of the 35kV bus voltage at the power supply side is shown in figure 7.

As can be seen from fig. 7, when the 35kV line is disconnected and the power supply side is grounded, the three line voltages are constant and symmetrical.

2. Load side bus voltage analysis

The 35kV load side bus voltage is analyzed as follows:

the vector diagram of the 35kV bus voltage on the load side is shown in figure 8.

When the 35kV line is broken, the load side

Is composed of

And

in the opposite direction and of magnitude

1.2 grounding System via a resistor

1.2.135 kV line broken wire

Fig. 9 is a schematic diagram of a 35kV primary disconnection system, taking an a-phase stub as an example. The 35KV power supply system of the 35kV side transformer substation of the upper-level transformer substation is grounded through a resistor (R is generally 10, 20 and 100 omega). The power supply potentials at 35kV sides of the upper-level transformer substation are respectively set as E_A、E_B、E_C，U_NIf alpha is broken for the 35kV neutral point voltage of the transformer of the power side transformer substation, the capacitance to ground of the bus side of the transformer substation from the broken line to the upper level is alpha C, and the capacitance to ground of the 35kV bus of the transformer substation from the broken line to the load side is (1-alpha) C.

1. Power supply side bus voltage analysis

(6) in the formula (I), the compound is shown in the specification,

the voltage of a power side 35kV bus A1B1 line, the voltage of a B1C1 line and the voltage of a C1A1 line are respectively. The vector diagram of the 35kV bus voltage on the power supply side is shown in FIG. 10.

As can be seen from fig. 10, when a phase a of the 35kV line is disconnected, the voltages of the three-phase lines of the 35kV bus of the upper-level substation are unchanged and are kept symmetrical. With the distance of the broken line close to the power supply side bus bar different, the 0 point is 0 in FIG. 10_α＝0To 0_α＝1When α is 1, point 0 is 0_α＝1At the point, when α is 0, 0 is 0_α＝0(same below) with U_NAt about ω CE_AThe variation from R to 0 (the cable line capacitance C is generally less than or equal to 0.55 mu F, and the overhead line is even smaller, so U_NIs a very small value, and is 0.55 mu F, U according to the grounding resistance of 20 omega, C_NIs 3.45^-3E_AAnd so can be ignored).

2. Load side bus voltage analysis

The 35kV load side bus voltage is analyzed as follows:

(7) in the formula (I), the compound is shown in the specification,

the line voltage of the load side 35kV bus A2B2, the line voltage of B2C2 and the line voltage of C2A2 are shown in a vector diagram of the load side 35kV bus in the figure 11.

As can be seen from FIG. 11, when the 35kV line is disconnected, the load side

Is composed of

And

in the opposite direction and of magnitude

1.2.235 kV line disconnection and load side disconnection grounding

Fig. 12 is a schematic diagram of a 35kV line break and load side line break grounding primary system, taking an a-phase stub as an example. The 35KV power supply system of the 35kV side transformer substation of the upper-level transformer substation is grounded through a resistor. The power supply potentials at 35kV sides of the upper-level transformer substation are respectively set as E_A、E_B、E_C，U_NThe voltage of a 35kV neutral point of a transformer substation on a power supply side is alpha C on the bus side of a transformer substation from a broken line to a superior substation, and the capacitance of the 35kV bus of the transformer substation from the broken line to a load side is (1-alpha) C.

1. Power supply side bus voltage analysis

The analysis was as in 1.2.1.

2. Load side bus voltage analysis

The 35kV load side bus voltage is analyzed as follows:

the vector diagram of the 35kV bus voltage on the load side is shown in FIG. 13.

As can be seen from FIG. 13, when the 35kV line is disconnected and the load side disconnection is grounded, U is turned off_B2C2Is equal to E_BCAnd the distance is different along with the distance of the broken line close to the power supply side bus. Due to U_NCan be ignored, so U_A2B2、U_C2A2Is about equal to E_BAnd E_C。

1.2.335 kV line disconnection and power supply side disconnection point grounding

Fig. 14 is a schematic diagram of a primary system with a 35kV line broken and a power supply side grounded, taking an a-phase short line as an example. The 35KV power supply system of the 35kV side transformer substation of the upper-level transformer substation is grounded through a resistor. The power supply potentials at 35kV sides of the upper-level transformer substation are respectively set as E_A、E_B、E_C，U_NThe voltage of a 35kV neutral point of a transformer substation on a power supply side is alpha C on the bus side of a transformer substation from a broken line to a superior substation, and the capacitance of the 35kV bus of the transformer substation from the broken line to a load side is (1-alpha) C.

When the line is broken and the system side is grounded, the fault is a single-phase grounding short circuit fault, so that the zero sequence current protection action of the system transformer substation line trips, and reclosure cannot be coincided.

Analyzing the line breaking fault characteristics of the 3-66 kV line:

for three conditions of ungrounded, arc suppression coil grounded and resistance grounded systems, 35kV line breakage and load side line breakage grounded, 35kV line breakage and power supply side line breakage grounded, the power supply side line voltage is constant and symmetrical (for the resistance grounded systems, when the line breakage and system side grounded, single-phase grounding short circuit fault occurs, the zero-sequence current protection of the line trips actions).

Due to the grounding condition of the broken line of the 35kV line and the broken line of the power supply side, U_NCan be ignored, so for the two conditions of 35kV line disconnection, 35kV line disconnection and grounding at the power supply side disconnection, the load side bus line voltage and the load side

Is equal to

And

in the opposite direction, largeIs small as

For the case that the 35kV line is broken and the load side is grounded,

is equal to

Alpha varies between 0 and 1 according to the distance between the broken line and the bus on the power supply side,

is as large as

Change to E_BWhile varying between

Is as large as

Change to E_CAnd (4) change.

In summary, when three conditions of 35kV line disconnection, 35kV line disconnection and grounding at the load side disconnection point, 35kV line disconnection and grounding at the power side disconnection point occur, the line voltage amplitude difference at the two sides of the line satisfies:

similarly, when a 3-66 kV line is broken, the bus line voltages on two sides of the line have the same fault characteristics.

The technical scheme of the method of the invention is as follows:

the transmission and distribution network applied by the method is 35kV single-bus subsection primary main connection (including 35kV single-bus primary main connection), 35kV inner bridging connection (shown in figure 17), 35kV expansion inner bridging connection (shown in figure 18) and 35kV line transformation group primary main connection (shown in figure 19) of a 35kV substation. Taking a 35kV substation as an example of a primary main connection of a 35kV single-bus subsection, other primary main connection protection methods are similar (in which fig. 19 is matched with a medium-voltage or low-voltage spare power automatic switch to recover power supply). The 35kV single-bus subsection primary main wiring general structure of the 35kV substation is as follows: the No. 1 power supply incoming line branch equipment and the No. 2 power supply incoming line branch equipment are respectively connected with a 35kV I section bus and a 35kV II section bus; a segmented circuit breaker 3DL is arranged between the 35kV first-segment bus and the second-segment bus, and the segmented circuit breaker 3DL is connected with a segmented current transformer CT in series; the circuit breaker 1DL is arranged at the interval of the No. 1 power supply inlet branch circuit, the circuit breaker 2DL is arranged at the interval of the No. 2 power supply inlet branch circuit, and the No. 1 power supply inlet branch circuit and the No. 2 power supply inlet branch circuit are respectively connected with a current transformer CT1 and a current transformer CT2 in series; in addition, the 35kV I section bus is also connected with a No. 1 transformer branch and a 35kV voltage transformer PT 1; the 35kV II section bus is also connected with a No. 2 transformer branch and a 35kV voltage transformer PT 2. There is circuit breaker 4DL No. 1 power inlet wire circuit power supply side, and there is circuit breaker 5DL No. 2 power inlet wire circuit power supply side. No. 1 power supply inlet wire power end 35kV generating line connects 35kV PT3, and No. 2 power supply inlet wire power end 35kV generating line connects 35kV PT 4. The 35kV line is provided with an optical fiber channel and line optical fiber differential protection.

Aiming at the 35kV single-bus subsection primary main connection, voltage information on two sides of a line is transmitted through a 35kV line optical fiber channel in an upper-stage transformer substation, line voltage amplitude difference on two sides of the line is compared to identify the line breakage of the 35kV line, and a load end 35kV transformer substation transfers load power supply by adopting a ring closing and opening operation to meet the field operation requirement. Based on the method, the method comprises the following steps:

as shown in fig. 15, the present invention includes:

1. condition for judging whether 35kV line is broken and the inlet line breaker is tripped after closing load end 35kV substation standby breaker

1.1 judging the conditions of 2DL or 3DL of a standby circuit breaker of a 35kV transformer substation at the on-load end of a No. 135kV circuit broken line and 1DL of a No. 1 trip incoming line circuit breaker, and starting a No. 135kV circuit broken line alarm condition

Acquiring voltage value U of secondary AB line of 35kV bus PT on power side_A1B1BC line voltage value U_B1C1CA line voltage value U_C1A1No. 135kV wire4DL switching-on position information of circuit power side breaker and load end 35kV transformer substation I section bus PT secondary AB line voltage value U_A2B2BC line voltage value U_B2C2CA line voltage value U_C2A2And 1DL switching-on position information of a breaker on the load side of a No. 135kV power incoming line. And sending the signals to 35kV disconnection protection in 35kV line protection of a 35kV transformer substation on the load side of the No. 135kV line.

(1) No. 135kV line 35kV power side and load end bus PT secondary line voltage value U_ABBC line voltage value U_BCCA line voltage value U_CAThree line voltages respectively satisfying the difference between the absolute value of the line voltage at the power supply side and the absolute value of the line voltage at the load side, two of which are 0.38E_abTo 0.55E_abOne is less than or equal to 0.1E_ab。

(2) Power end corresponds 35kV generating line PT secondary AB line voltage value U_A1B1Greater than or equal to 0.9E_ab1.1E or less_ab；

(3) Power end corresponds 35kV generating line PT secondary BC line voltage value U_B1C1Greater than or equal to 0.9E_ab1.1E or less_ab；

(4) Power end corresponds 35kV generating line PT secondary CA line voltage value U_C1A1Greater than or equal to 0.9E_ab1.1E or less_ab；

(5) The power supply end 35kV line breaker 4DL of the No. 135kV line is at the on position.

(6) The load side 35kV line breaker 1DL of No. 135kV line is in the on position.

And if the conditions are all met, identifying and judging that the No. 135kV power line is broken, protecting the 35kV broken line in the No. 135kV line protection of the load-end 35kV transformer substation, and tripping off the No. 1 No. 35kV power line load-side circuit breaker 1DL after switching on the standby power circuit breaker 2DL or 3DL to recover the transformer without the power supply to the standby power line for power supply. And simultaneously, starting No. 135kV line disconnection alarm.

1.2 judging the conditions of 1DL or 3DL of the spare circuit breaker of the 35kV transformer substation at the on-load end of the No. 235kV circuit disconnection and 2DL of the trip No. 2 incoming line circuit breaker, and starting the condition of the No. 235kV circuit disconnection alarm

Acquiring voltage value U of secondary AB line of 35kV bus PT on power side_A1B1BC line voltage value U_B1C1CA line voltage value U_C1A1No. 235kV line power supply side circuit breaker 5DL switching-on position information, load end 35kV transformer substation I section bus PT secondary AB line voltage value U_A2B2BC line voltage value U_B2C2CA line voltage value U_C2A2And 2DL switching-on position information of a breaker on the load side of a No. 235kV power incoming line.

(1) Power supply side and load end bus PT secondary line voltage value U_ABBC line voltage value U_BCCA line voltage value U_CAThree line voltages respectively satisfying the difference between the absolute value of the line voltage at the power supply side and the absolute value of the line voltage at the load side, two of which are 0.38E_abTo 0.55E_abOne is less than or equal to 0.1E_ab。

(5) And a power supply end 35kV line breaker 5DL of the No. 235kV line is at the switching-on position.

(6) The load side 35kV line breaker 2DL of 35kV line No. 2 is in the on position.

And if the conditions are all met, identifying and judging that the No. 235kV power line is broken, protecting the 35kV broken line in the No. 2 kV 35kV line protection of the load-end 35kV transformer substation, and tripping off the No. 2 No. 35kV power line load-side circuit breaker 2DL after starting to close the standby power circuit breaker 1DL or 3DL so as to recover the transformer without the power supply to the standby power line for power supply. And simultaneously, starting No. 235kV line disconnection alarm.

1.3 in 1.1 and 1.2 above:

(1) the method can be applied to a mode that the neutral point of the transformer is not grounded or is grounded through an arc suppression coil and a low-resistance grounding system.

(2) The reason that the circuit breakers 1DL or 2DL, 4DL or 5DL on the two sides of the 35kV power inlet wire are arranged at the switching-on position is as follows: when a 35kV transformer substation with a load end of a power supply incoming line is used, the bus voltage far away from the power supply incoming line can also sense the line disconnection information, and the action behavior of the device can be interfered; in addition, when a line PT is adopted, the power supply incoming line may have other load end 35kV substations, and if the power supply incoming line breaker of the load end 35kV substation trips slowly or refuses tripping, the action behavior of the device can be interfered. The condition that the circuit breakers on the two sides of the inlet wire of the 35kV power supply are in the switching-on position can further optimize logic.

(3)E_abFor the rated line voltage value of the power supply, the voltage fluctuation of the power grid is considered, and the voltage fluctuation is considered according to +/-10% of the rated voltage value of the actual power grid, wherein: when the voltage value is larger than or equal to the rated line voltage value, the rated line voltage value of the power grid is considered to be 0.9 times; the rated line voltage value is less than or equal to 1.1 times of the rated voltage value of the power grid.

(4) For the load side substation bus load which is in open-phase operation due to line break, the method of firstly closing the standby power supply circuit breaker and then tripping the load side circuit breaker of the broken line is adopted in the load side substation, the load is automatically transferred, and the power supply is recovered to the standby line. If the 35kV transformer substation adopts primary main wiring of a 35kV line transformer set, the high-voltage side circuit breaker and the low-voltage side circuit breaker of the load side transformer are adopted by the low-voltage side of the load side transformer substation, the standby power supply circuit breaker is closed firstly, then the broken line circuit is tripped, the load is automatically transferred, and the power supply is restored to the standby bus.

(5) And voltage information and circuit breaker position information on two sides of the line are transmitted through the line optical fiber channel.

2. The operation mode of the 35kV neutral point of the main transformer on the I section or II section of the bus of the load end 35kV transformer substation is ungrounded. No. 1 and No. 2 power supply 35kV lines are required to be provided with optical fiber channels and line optical fiber differential protection.

3. The method can be implemented in a single 35kV line disconnection protection device of a load-end 35kV transformer substation or can also be implemented in a 35kV line protection device. The 35kV line protection device implemented in the 35kV transformer substation at the load end has the advantage that no hardware equipment needs to be added.

The PT secondary voltage setting value when the buses on the two sides of the 4.35kV line are broken is as follows:

(1) dividing the PT secondary line voltages of a power supply side bus and a load side bus into three groups according to the AB line voltage, the BC line voltage and the CA line voltage for comparison, wherein the PT secondary side voltage amplitude difference setting values are as follows:

1) two of the two sets of the setting values are that the setting value of the difference between the absolute value of the line voltage of the power supply side and the absolute value of the line voltage of the load end meets the following requirements: is greater than or equal to the rated line voltage value

The voltage value of the rated line is less than or equal to 55 percent (1.1 x (1-0.5)), and the voltage value of the PT secondary rated line is 100V, namely more than or equal to 38V and less than or equal to 55V;

2) and the setting value of the difference between the absolute value of the line voltage of the power supply side and the absolute value of the line voltage of the load end of the rest group satisfies the following conditions: less than or equal to 10 percent of rated line voltage value, namely less than or equal to 10V.

(2) The setting value of the PT secondary line voltage of the power supply side bus meets the following requirements: the voltage value of the rated line is more than or equal to 90 percent and less than or equal to 110 percent, namely more than or equal to 90V and less than or equal to 110V.

5. The time setting value in the single-phase disconnection relay protection method for transferring load power supply by adopting ring closing and opening operation at the load end 35kV transformer substation is as follows:

t 1: avoiding the three-phase different-period time when the switch is switched on, and taking 0.1-0.2 second;

6. the scheme of the invention can meet the following primary main wiring: (1) a 35kV single-bus subsection primary main wiring of a 35kV transformer substation; (2) a 35kV transformer substation 35kV inner bridge primary main wiring; (3) a 35kV transformer substation 35kV enlarges primary main wiring; (4) a 35kV transformer substation 35kV line group-changing primary main wiring; (5) other primary main connections.

7. For a 35kV line with branch lines, 35kV line breakage protection of pairwise correspondence between a power end-load end substation and each load end substation needs to be implemented.

8. The scheme of the invention can also be used in the case of the disconnection of a 110kV line powered by a single power supply.

An example of the process of the invention is given below (taking fig. 16 as an example):

mode of operation 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.

For example, if phase A is broken, phase B or phase C is broken similarly. When the No. 235kV power supply line A phase single-phase disconnection fault occurs, abnormal operation of the line is sensed by comparing the voltage amplitude difference of 35kV bus lines on two sides, meanwhile, the secondary line voltage of a power end substation 35kV bus PT is normal, the condition that the No. 235kV power supply line single-phase disconnection is met, after the time delay t1, the 35kV line in the load end line protection is disconnected, the No. 135kV standby power supply circuit breaker 1DL is started to be switched on, the No. 2 kV power supply incoming line circuit breaker 2DL is switched off, and the transformer losing the power supply is enabled to be recovered to the standby No. 1 kV power supply line for supplying power. And reporting the single-phase disconnection fault of the No. 235kV power line.

Mode of operation 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.

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. 135kV power line occurs, abnormal operation of the line is sensed by comparing the voltage amplitude difference of 35kV bus lines on two sides, meanwhile, the secondary line voltage of the 35kV bus PT of a power end substation is normal, the condition that the phase-A single-phase disconnection of the No. 135kV power line is met, after the time delay t1, the 35kV line in the load end line protection is disconnected, after the 2 # 35kV standby power circuit breaker 2DL is started to be switched on, the 1 # 35kV power incoming line breaker 1DL is switched off, and the transformer losing the power supply is enabled to be recovered to the power supply on the 2 # 35kV standby power line. And simultaneously reporting the single-phase line break fault of the No. 135kV power line.

Mode for operation 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. 135kV 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. 135kV power line occurs, abnormal operation of the line is sensed by comparing the voltage amplitude difference of 35kV bus lines on two sides, meanwhile, the secondary line voltage of the 35kV bus PT of a power end substation is normal, the condition of the single-phase disconnection of the No. 135kV power line is met, after the time delay t1, the 35kV line in the load end line protection is disconnected, after the 35kV standby power circuit breaker 3DL is started to be switched on, the No. 135kV power incoming line breaker 1DL is switched off, and the transformer losing the power supply is enabled to be recovered to the power supply on the No. 235kV standby power line. And simultaneously reporting the single-phase line break fault of the No. 135kV power line.

No. 235kV power line single-phase line break fault

For example, if phase A is broken, phase B or phase C is broken similarly. When the No. 235kV power line A phase single-phase disconnection fault occurs, abnormal operation of the line is sensed by comparing the voltage amplitude difference of 35kV bus lines on two sides, meanwhile, the secondary line voltage of a power end substation 35kV bus PT is normal, the condition that the No. 235kV power line single-phase disconnection is met, after the time delay t1, the 35kV line in load end line protection is protected, after the 35kV standby power circuit breaker 3DL is started to be switched on, the No. 235kV power line load side breaker 5DL is switched off, and the transformer losing the power supply is enabled to be recovered to the standby No. 1 kV power line for supplying power. And reporting the single-phase disconnection fault of the No. 235kV power line.

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

1. A line disconnection protection method for comparing voltage amplitude difference between two lateral lines of a line is characterized by comprising the following steps:

conditions are as follows: (1) in No. 1 circuit, the voltage value U of the secondary AB line of the power supply side bus PT_A1B1Absolute value and load end transformer substation I section bus PT secondary AB line voltage value U_A2B2Difference of absolute value, secondary BC line voltage value U of power side bus PT_B1C1Absolute value and load end transformer substation I section bus PT secondary BC line voltage value U_B2C2Difference of absolute value, power source side bus PT secondary CA line voltage value U_C1A1Absolute value and load end transformer substation I section bus PT secondary CA line voltage value U_C2A2Of the three differences, two differences being 0.38E_abTo 0.55E_abA difference of 0.1E or less_ab；E_abThe voltage value of a secondary side rated line of a power supply PT;

(6) the 1 st line load side breaker 1DL is in the on position;

if the conditions are all met, identifying and judging that the No. 1 power supply circuit is disconnected, after t1 delay time, performing disconnection protection action in the No. 1 circuit protection of the load-side substation, starting to close the standby power supply circuit breaker 2DL or 3DL, tripping off the No. 1 circuit load-side circuit breaker 1DL, recovering the transformer without the power supply to the standby power supply circuit for power supply, and starting No. 1 circuit disconnection alarm;

collecting power supply side bus PT secondary AB line voltage value U_A1B1BC line voltage value U_B1C1CA line voltage value U_C1A1No. 2 line power supply side circuit breaker 5DL switching-on position information, load end I section bus PT secondary AB line voltage value U of transformer substation_A2B2BC line voltage value U_B2C2CA line voltage value U_C2A22DL switching-on position information of a breaker at the load side of the No. 2 power incoming line; sending the signals to disconnection protection in the load side transformer substation line protection of the No. 2 line;

(3) Power supply end corresponding bus PT secondary BC line voltage value U_B1C1Greater than or equal to 0.9E_abIs small and smallIs equal to or greater than 1.1E_ab；

(6) the load side line breaker 2DL of line No. 2 is in the on position;

2. A method for protecting a line from disconnection by comparing the voltage amplitudes of both sides of the line according to claim 1, wherein the method is applied to the mode that the neutral point of the transformer is not grounded or is grounded through an arc suppression coil or is grounded through a small resistor.

3. The line break protection method of comparing the voltage amplitude difference between two sides of the line as claimed in claim 1, wherein the secondary side rated line voltage E of the power supply PT_abIs 100V.

4. The line disconnection protection method for comparing the voltage amplitude difference between two sides of a line according to claim 1, wherein the time delay t1 is 0.1-0.2 seconds to avoid the three-phase asynchronous time when the breaker is switched on.