CN110912092B

CN110912092B - 3-66 kV line disconnection protection method for comparing line voltages on two sides of line

Info

Publication number: CN110912092B
Application number: CN201911247166.2A
Authority: CN
Inventors: 刘昶; 胡浩; 马骏毅; 姜正驰; 朱燕妮; 汤勋; 赵伟; 周杨; 陈泽
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: 2021-03-30
Anticipated expiration: 2039-12-09
Also published as: CN110912092A

Abstract

The invention discloses a 3-66 kV line disconnection protection method for comparing line voltages on two sides of a line, which is used for a load end 3-66 kV transformer substation. 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 at two sides of the line is compared to identify line disconnection, and the power supply is transferred by a load-side transformer substation through a switching-on/off loop operation, so that the transformer losing the power supply is recovered to the standby power supply to supply power, thereby effectively preventing the influence of the transformer on the power grid and the load power supply due to phase-off power supply and being beneficial to the safe and stable operation of the power grid.

Description

3-66 kV line disconnection protection method for comparing line voltages on two sides of line

Technical Field

The invention relates to a 3-66 kV line disconnection protection method for comparing line voltages on two sides of a line, and belongs to the technical field of protection and control of power transmission and distribution networks.

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 used for transmitting voltage information of two sides of a line through a line optical fiber channel at a load end transformer substation, comparing line voltages of the two sides of the line, identifying 3-66 kV line breaking and transferring power supply by adopting ring closing and opening operation.

Disclosure of Invention

The invention aims to provide a 3-66 kV line disconnection protection method for comparing line voltages on two sides of a line, which is used for a 3-66 kV transformer substation at a load end, transmits voltage information on the two sides of the line through a line optical fiber channel, compares the line voltages on the two sides of the line, identifies line disconnection, and adopts a single-phase disconnection relay protection method for transferring power supply by adopting a ring closing and opening operation.

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

a3-66 kV line disconnection protection method for comparing line voltages on two sides 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 conditions of No. 1 line broken line closing load end substation standby circuit breaker 2DL or 3DL and tripping No. 1 incoming line circuit breaker 1DL, and starting No. 1 line broken line alarm condition

a. Acquiring secondary AB line voltage value U of bus PT corresponding to upper-level transformer substation_abBC line voltage value U_bcCA line voltage value U_ca；

Conditions are as follows: (1) power supply end corresponding bus PT secondary AB line voltage value U_abGreater than or equal to rated power line voltage 0.9E_abRated supply line voltage E of 1.1 or less_ab；

(2) Power supply end corresponding bus PT secondary BC line voltage value U_bcRated power line voltage E greater than or equal to 0.9_abRated supply line voltage E of 1.1 or less_ab；

(3) Power supply end corresponding bus PT secondary CA line voltage value U_caRated power line voltage E greater than or equal to 0.9_abRated supply line voltage E of 1.1 or less_ab；

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

all the conditions are met, and the condition shows that 3 line voltages of the transformer substation bus on the upper power supply side are symmetrical (the amplitudes are basically equal), namely the voltage on the power supply side is normal (hereinafter referred to as normal voltage); the normal voltage signal is transmitted to the disconnection protection in the load substation line protection of the No. 1 line through an optical fiber channel of the No. 1 power supply line optical fiber differential protection;

b. acquiring voltage value U of secondary AB line of I-section bus PT of load-end transformer substation_abBC line voltage value U_bcCA line voltage value U_ca；

Conditions are as follows: (1) a load end incoming line breaker 1DL of the No. 1 power line is at a switching-on position;

(2) load end I section bus PT secondary AB line voltage value U_abBC line voltage value U_bcCA line voltage value U_caOf the three line voltages, two values greater than or equal to 0.45E are satisfied_abAnd is not more than 0.635E_abA value of 0.9E or more_abAnd is not more than 1.1E_ab；

The conditions are all met, and the condition indicates that the voltage of the I-section bus of the load-end transformer substation is abnormal (hereinafter referred to as voltage abnormity);

when the corresponding bus of the upper-stage transformer station is normal and the voltage of the I-section bus of the load-end transformer station is abnormal, identifying and judging that the No. 1 power supply circuit is broken, carrying out broken line protection in the circuit protection of the load-end transformer station, and tripping the No. 1 power supply circuit load-side circuit breaker 1DL after switching on the standby power supply circuit breaker 2DL or 3DL to recover the transformer without power supply to the standby power supply circuit for power supply; simultaneously starting No. 1 line disconnection alarm;

1.2 judging the condition of No. 2 line broken line closing load end substation standby circuit breaker 1DL or 3DL and tripping No. 2 incoming line circuit breaker 2DL, and starting the condition of No. 2 line broken line alarm

Conditions are as follows: (1) power supply end corresponding bus PT secondary AB line voltage value U_abRated power line voltage E greater than or equal to 0.9_abRated supply line voltage of 1.1 or lessE_ab；

the conditions are all met, and the condition indicates that the voltage of the corresponding bus bar of the superior substation is normal; the normal voltage signal is transmitted to the disconnection protection in the load substation line protection of the No. 2 line through an optical fiber channel of the No. 2 power supply line optical fiber differential protection;

b. acquiring secondary AB line voltage value U of II-section bus PT of load-end transformer substation_abBC line voltage value U_bcCA line voltage value U_ca；

(1) A load end incoming line breaker 2DL of the No. 2 power line is at the switching-on position;

(2) load end II section generating line PT secondary AB line voltage value U_abBC line voltage value U_bcCA line voltage value U_caOf the three line voltages, two values are satisfied, wherein the two values are more than or equal to 0.45 rated power line voltage E_abAnd less than or equal to 0.635 rated power line voltage E_abA rated power line voltage E greater than or equal to 0.9_abAnd less than or equal to 1.1 rated power line voltage E_ab；

When the conditions are met, the voltage of the second section of the bus of the load-end substation is abnormal;

when the corresponding bus of the upper-stage transformer station is normal and the voltage of the second-stage bus of the load-end transformer station is abnormal, the No. 2 power circuit is identified and judged to be broken, the broken circuit protection in the load-end transformer station circuit protection is started, and after the closing of the standby power circuit breaker 1DL or 3DL, the No. 2 power circuit load-side circuit breaker 2DL is tripped, so that the transformer losing the power supply is recovered to the standby power circuit to supply power, and meanwhile, the No. 2 circuit disconnection alarm is started.

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

the 3-66 kV line disconnection protection method for comparing line voltages on two sides of the line is applied to a mode that a neutral point of a transformer is not grounded or is grounded through an arc suppression coil and a low-resistance grounding system.

The 3-66 kV line disconnection protection method comparing line voltages at two sides of the line, PT secondary side rated line voltage value E_abIs 100V.

According to the 3-66 kV line disconnection protection method for comparing the line voltages on the two sides of the line, t1 is 0.1-0.2 second when 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 power supply end and the load end substation bus PT when the single-phase line is broken, compares the bus line voltages at two ends of the line, identifies the single-phase line break of the line, and transfers power supply by the load end substation by adopting ring closing and ring opening operation, thus being simple and easy to implement.

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 at two sides of the line is compared to identify line disconnection, and the power supply is transferred by a load-side transformer substation through a switching-on/off loop operation, so that the transformer losing the power supply is recovered to the standby power supply to supply power, thereby effectively preventing the influence of the transformer on the power grid and the load power supply due to phase-off 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 disconnection as an example (3, 6, 10, 20 and 66kV lines are the same):

1.1 ungrounded or arc-suppression coil grounding system

1.1.135 kV line broken wire

Fig. 1 is a schematic diagram of a 35kV primary disconnection system, taking an a-phase stub as an example. 35kV side of upper-level transformer substation is not connectedThe ground or the arc suppression coil is 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_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

1.1.235 kV 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.

From FIG. 5It is known that, 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). 35kV side power supply of superior transformer substationPotential is respectively 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 and of magnitude

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.

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 the primary main connection of a 35kV single bus subsection in a 35kV substation as an example, the protection method of other primary main connections is similar. 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, the method comprises the steps of transmitting voltage information of two sides of a line through a 35kV line optical fiber channel in an upper-level transformer substation, comparing line voltages of two sides of the line to identify the line breakage of the 35kV line, and adopting a scheme of switching on and off loop operation to transfer load power supply by a load-side 35kV transformer substation to meet the requirement of field operation.

As shown in fig. 15, the method for protecting a 3-66 kV line from disconnection by comparing line voltages at two sides of the line, provided by the invention, comprises the following steps:

first, judging the condition of tripping on the incoming line breaker after the line breaking and closing the load end 35kV substation standby breaker

Conditions are as follows: (1) power end pairVoltage value U of secondary AB line of reactor bus PT_abGreater than or equal to rated power line voltage 0.9E_abRated supply line voltage E of 1.1 or less_ab；

Conditions are as follows: (1) power supply end corresponding bus PT secondary AB line voltage value U_abRated power line voltage E greater than or equal to 0.9_abRated supply line voltage E of 1.1 or less_ab；

(2) load end II section generating line PT secondary AB line voltage value U_abBC line voltage value U_bcCA line voltage value U_caOf the three line voltages, two values are satisfied, wherein the two values are more than or equal to 0.45 rated power line voltage E_abAnd less than or equal to 0.635 rated power line voltageE_abA rated power line voltage E greater than or equal to 0.9_abAnd less than or equal to 1.1 rated power line voltage E_ab；

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 and 4DL or 5DL on the two sides of the power supply inlet wire are arranged at the switching-on position is as follows: when a power supply incoming line is provided with a load end substation, 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 the line PT is adopted, the power incoming line may have other load side power substations, and if the power incoming line breaker of the load side power substation trips slowly or refuses tripping, the action behavior of the device is also interfered. The logic can be further optimized by adopting the condition of the power incoming line breaker at the closing position.

(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 bus load of the load-side substation which is in open-phase operation due to wire breakage, the load-side substation adopts the load-side circuit breaker which closes the standby power supply circuit breaker firstly and then trips the broken line circuit, so that the load is automatically transferred and the power supply is restored to the standby circuit. If the transformer substation adopts primary main wiring of line transformer group, the low-voltage side in the load side transformer substation adopts the high-voltage side circuit breaker and the low-voltage side circuit breaker of the load side transformer which firstly closes the standby power supply circuit breaker and then trips off the broken line circuit, so that the load is automatically transferred and the power supply is restored to the standby low-voltage bus.

2. The operation mode of the neutral point of the main transformer on the first section or the second section of the bus of the load end transformer substation is ungrounded. The power lines No. 1 and No. 2 must be provided with fibre channel and line fibre differential protection.

3. The method is implemented in a single line disconnection protection device of a load-end substation or in a line protection device; the advantages implemented in the load side substation line protection device are as follows: no additional hardware devices are required.

4. The secondary setting value of the line breaking phase PT of the first section bus or the second section bus of the load end transformer substation is as follows:

load end bus PT secondary AB line voltage value U_abBC line voltage value U_bcCA line voltage value U_caSetting values of three line voltages are as follows: two of the two are equal to or greater than 45% (0.9 x 0.5) of the rated line voltage value and equal to or less than the rated line voltage value

PT secondary rated line voltage value E_abIs 100V, namely more than or equal to 45V and less than or equal to 63.5V; one is greater than or equal to 90% of the rated line voltage value and less than or equal to 110% of the rated line voltage value, namely, greater than or equal to 90V and less than or equal to 110V.

5. The secondary setting value of the power supply end transformer substation bus PT during line disconnection is as follows:

power supply end bus PT secondary AB line voltage value U_abBC line voltage value U_bcCA line voltage value U_caSetting values of three line voltages are as follows: PT secondary rated line voltage value E_abThe voltage is 100V, the voltage value is more than or equal to 90 percent of the rated line voltage value and less than or equal to 110 percent of the rated line voltage value, namely more than or equal to 90V and less than or equal to 110V.

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

t 1: and (3) avoiding the three-phase different-period time when the switch is switched on, and taking 0.1-0.2 second.

7. 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.

8. 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.

9. The scheme of the invention for comparing the bus line voltages on two sides of the line can also be used in the case of the disconnection of the 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):

operation 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.

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 35kV power line occurs, the line voltage of the second section of the bus of the transformer substation at the load end is sensed to be abnormally operated, but the secondary line voltage of the PT of the 35kV bus of the transformer substation at the power end is normal, the condition of the single-phase disconnection of the No. 2 kV power line is met, after the time delay t1, the line disconnection protection of the 35kV line in the line protection at the load end is carried out, after the circuit breaker 1DL of the No. 1 35kV standby power supply is started to be switched on, the circuit breaker 2DL of the No. 2 kV power incoming line of the 35kV transformer substation at the load end is. And meanwhile, a No. 2 35kV power line single-phase disconnection signal is sent.

Operation 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.

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. 1 35kV power line occurs, the voltage inductance of the I section bus of the load end transformer substation is abnormally operated, but the PT secondary line voltage of the 35kV bus of the power end transformer substation is normal, the single-phase disconnection condition of the No. 1 35kV power line is met, after the time delay t1, the 35kV line in the load end line protection is protected, after the 2DL of the 2 # 35kV standby power circuit breaker is started to be switched on, the 1DL of the 1 # 35kV power incoming line breaker of the load end 35kV transformer substation is switched off, and the transformer losing power is enabled to be recovered to the power supply on the 2 # 35kV standby power circuit. And simultaneously sending a No. 1 35kV power line single-phase disconnection signal.

Operation 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. 1 35kV power line single-phase disconnection 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. 1 35kV power line occurs, the voltage inductance of the I section bus of the load end transformer substation is abnormally operated, but the PT secondary line voltage of the 35kV bus of the power end transformer substation is normal, the single-phase disconnection condition of the No. 1 35kV power line is met, after the time delay t1, the 35kV line in the load end line protection is protected, after the 35kV standby power circuit breaker 3DL is started to be switched on, the No. 1DL of the 35kV power incoming line breaker of the load end transformer substation is switched off, and the transformer losing the power supply is recovered to the No. 2 No. 35kV standby power line for power supply. And simultaneously sending a No. 1 35kV power line single-phase disconnection signal.

No. 2 35kV power line single-phase disconnection 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 35kV power line occurs, the voltage sense of the second section of the bus of the load-end substation is abnormally operated, but the PT secondary line voltage of the 35kV bus of the power-end substation is normal, the single-phase disconnection condition of the No. 2 35kV power line is met, after the time delay t1, the 35kV line in the power-end line protection is protected, after the 35kV standby power circuit breaker 3DL is started to be switched on, the No. 2 35kV power incoming line circuit breaker 2DL of the load-end substation is switched off, and the transformer losing power is recovered to the standby No. 1 kV power line for power supply. And meanwhile, a No. 2 35kV power line single-phase disconnection signal is sent.

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. A3-66 kV line disconnection protection method for comparing line voltages on two sides of a line is characterized by comprising the following steps:

1.1 judging No. 1 line breaking, after delay time t1, closing No. 2 line load side breaker 2DL or sectional breaker 3DL and tripping No. 1 line load side breaker 1DL, and starting No. 1 line breaking alarm condition

Conditions are as follows: (1) power supply end corresponding bus PT secondary AB line voltage value U_abGreater than or equal to 0.9E_ab1.1E or less_ab；

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

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

(4) The 1 st line power supply side breaker 4DL is in the on position;

E_abthe voltage value of a secondary side rated line of a power supply PT;

all the conditions are met, and 3 line voltages of the buses of the transformer substation on the upper power supply side are symmetrical, namely the voltage on the power supply side is normal; the normal voltage signal is transmitted to the disconnection protection in the load substation line protection of the No. 1 line through an optical fiber channel of the No. 1 power supply line optical fiber differential protection;

b. acquiring voltage value U of secondary AB line of I-section bus PT of load-end transformer substation_abBC line voltage value U_bcCA line voltage value U_ca

Conditions are as follows: (1) the 1 st line load side breaker 1DL is in the on position;

The conditions are all met, and the voltage of the first-section bus of the load-end substation is abnormal;

when the corresponding bus of the upper-stage transformer station is normal and the voltage of the I-section bus of the load-end transformer station is abnormal, identifying and judging the disconnection of the No. 1 line, performing disconnection protection in the line protection of the load-end transformer station, after the delay time t1, starting to close the No. 2 line load-side circuit breaker 2DL or the segmented circuit breaker 3DL, tripping off the No. 1 line load-side circuit breaker 1DL, restoring the transformer without the power supply to the standby power line for supplying power, and starting the No. 1 line disconnection alarm;

1.2 judging No. 2 line breaking, after delay time t1, closing No. 1 line load side breaker 1DL or sectional breaker 3DL and tripping No. 2 line load side breaker 2DL, and starting No. 2 line breaking alarm condition

(4) The 1 st line power supply side breaker 4DL is in the on position;

(1) The circuit breaker 2DL on the load side of the line 2 is at the closing position;

(2) load end II section generating line PT secondary AB line voltage value U_abBC line voltage value U_bcCA line voltage value U_caOf the three line voltages, two values greater than or equal to 0.45E are satisfied_abAnd is not more than 0.635E_abOne is 0.9E or more_abAnd is not more than 1.1E_ab；

when the corresponding bus of the upper-stage transformer station is normal and the voltage of the second-stage bus of the load-end transformer station is abnormal, the No. 2 circuit is identified and judged to be broken, the broken circuit protection in the load-end transformer station is started after the delay time t1, the No. 1 circuit load-side circuit breaker 1DL or the segmented circuit breaker 3DL is closed, the No. 2 circuit load-side circuit breaker 2DL is tripped, the transformer losing the power supply is recovered to the standby power supply line to supply power, and the No. 2 circuit breakage alarm is started at the same time.

2. The method for protecting the disconnection of the 3-66 kV line by comparing the line voltages on two sides of the line according to claim 1, which is applied to a mode that a neutral point of a transformer is not grounded or is grounded through an arc suppression coil or is grounded through a small resistor.

3. The method for protecting the disconnection of the 3-66 kV line by comparing the line voltages on two sides of the line as claimed in claim 1, wherein the secondary side rated line voltage value E of the power supply PT_abIs 100V.

4. The method for protecting the broken line of the 3-66 kV line with the line voltages on the two sides of the line compared according to claim 1, wherein the delay time t1 is 0.1-0.2 second when the three phases are not in phase when the breaker is switched on.