CN111313379A - Disconnection protection method for comparing line voltage on two sides of line and spare power automatic switching - Google Patents

Abstract

The invention discloses a disconnection protection method for comparing the line voltage on both sides of the line and the coordination of the standby automatic switching. The busbar voltage at both ends is simple and easy to identify the single-phase disconnection of the line and jump the circuit breaker on the power supply side or the load side circuit breaker. The invention adopts the transmission of voltage information on both sides of the line through the line optical fiber channel, compares the line voltage on both sides of the line to identify the line disconnection, jumps the circuit breaker on the power supply side or the circuit breaker on the load side, and then the substation at the load end is prepared for automatic switching action, and the tripping is started. The incoming circuit breaker and the backup power circuit breaker are closed, so that the transformer that has lost its power can be restored to the backup power supply, which can effectively prevent the impact of the transformer's lack of phase power supply on the power grid and the load power supply, and is conducive to the safe and stable operation of the power grid. The method of the invention is implemented by using line protection devices on both sides of the line, and no additional hardware equipment is required.

Description

Comparing the line voltage on both sides of the line and the disconnection protection method of the standby automatic switching

technical field

The invention relates to a disconnection protection method for comparing the line voltage on both sides of the line and the coordination of the backup and automatic switching, belonging to the technical field of protection and control of electric power transmission and distribution networks.

Background technique

At present, the 3~66kV (including 3, 6, 10, 20, 35, and 66kV) lines are disconnected in the power grids in various places. The disconnection causes the transformer supplying the line to operate without phase, making the three-phase voltage of the transformer asymmetrical, and supplying power to the load. It may cause damage to electrical equipment, such as causing damage to the motor due to lack of phase operation. In the prior art, there is no relay protection device and method specifically aimed at the disconnection of 3-66kV lines. The invention will propose a method to transmit the voltage information on both sides of the line through the line optical fiber channel in the load-side substation, compare the line voltages on both sides of the line to identify the 3-66kV line disconnection, jump the line power-side circuit breaker or the load-side circuit breaker, and transfer the voltage information on both sides of the line to the load-side substation. Single-phase disconnection relay protection method for 3~66kV standby power supply recovery by self-switching.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a disconnection protection method for comparing the line voltage on both sides of the line and the coordination of the automatic switching, which is used in a 3-66kV substation at the load end, transmits the voltage information on both sides of the line through the line fiber channel, and compares the line voltage on both sides of the line to identify When the line is disconnected, the circuit breaker on the power supply side or the circuit breaker on the load side is jumped, and the single-phase disconnection relay protection method is used to restore the power supply by the 3~66kV substation at the load end.

The object of the present invention is achieved through the following technical solutions:

A disconnection protection method for comparing the line voltage on both sides of the line and the cooperation of the standby automatic switching, comprising:

1. Judging the conditions for line disconnection to start jumping the circuit breaker on the power supply side or the circuit breaker on the load side and restoring the power supply by the backup

1.1 Judging the disconnection of Line 1, jumping the circuit breaker 4DL on the power supply side of the disconnected line No. 1 and the self-switching start-up of the load end to close the standby power circuit breaker 2DL or 3DL, and starting the disconnection alarm condition of Line 1:

a. Collect the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT in section I of the substation at the load end;

(1) The incoming circuit breaker 1DL at the load end of the No. 1 power line is in the closing position;

(2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT of the first section of the load end, two values are satisfied between 0.45E _ab and 0.635E _ab Between, a value is between 0.9E _ab to 1.1E _ab , E _ab is the rated line voltage value of the power supply;

All of the above conditions are satisfied, indicating that the voltage of the busbar of the first section of the substation at the load end is abnormal (hereinafter referred to as the voltage abnormality). The disconnection protection in the line protection of the power supply end of the No. 1 line of the upper substation;

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation;

(1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The circuit breaker 4DL at the power end of Line 1 is in the closed position;

All the above conditions are satisfied, which means that the three line voltages of the busbar of the substation on the upper power supply side are symmetrical (the amplitudes are basically equal), that is, the voltage on the power supply side is normal (referred to as normal voltage);

When the voltage of the corresponding busbar of the power-side substation is normal, and the received busbar voltage of the load-side substation I section is abnormal, then identify and judge the disconnection of the No. 1 power supply line, the disconnection protection in the line protection of the upper substation, and skip the No. 1 power supply line The circuit breaker on the power supply side is 4DL; due to the loss of power on the No. 1 power supply line, the substation at the load side will automatically switch on the power supply, start to trip the No. 1 power supply incoming circuit breaker 1DL, and close the standby power circuit breaker 2DL or 3DL, so that the transformer that loses power will be turned on. Restore the power supply to the standby power line; at the same time start the No. 1 line disconnection alarm;

1.2 Judging the conditions for the disconnection of Line 2 to jump the circuit breaker 5DL on the power supply side of Line 2 and the self-switching start-up circuit breaker 1DL or 3DL from the load side to activate the disconnection alarm of Line 2:

a. Collect secondary AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of busbar PT in section II of the substation at the load end;

(1) The incoming circuit breaker 2DL at the load end of the No. 2 power line is in the closing position;

(2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the second section busbar PT at the load end, two values are within the range of 0.45E _ab to 0.635E _ab between 0.9E _ab to 1.1E _ab ;

If the above conditions are met, it means that the voltage of the busbar of the second section of the substation at the load end is abnormal. Through the optical fiber channel of the optical fiber differential protection of the No. 2 power supply line, the above voltage and the abnormal signal of the busbar voltage of the second section of the substation at the load end are sent to the power supply of the No. 1 line of the upper substation. Disconnection protection in end line protection;

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation;

(1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The circuit breaker 5DL at the power end of Line 2 is in the closed position;

All of the above conditions are met, indicating that the voltage of the corresponding busbar of the upper substation is normal;

When the voltage of the corresponding busbar of the upper substation is normal, and the received voltage of the busbar of the second section of the substation at the load end is abnormal, then identify and judge that the No. 2 power supply line is disconnected, and the disconnection protection in the line protection of the upper substation, skip the No. 2 power supply line The circuit breaker on the power supply side is 5DL; due to the loss of power on the No. 2 power supply line, the substation at the load side will act as a backup and start to trip the circuit breaker 2DL on the incoming line of the No. 2 power supply, and close the standby power circuit breaker 1DL or 3DL to make the transformer without power supply Restore the power supply to the standby power line; at the same time start the No. 2 line disconnection alarm;

1.3 Judging that the No. 1 line is disconnected, the load-side circuit breaker 1DL of the No. 1 disconnected line is jumped, and the load-side self-switching start and the standby power circuit breaker 2DL or 3DL, and the No. 1 line disconnection alarm condition is activated:

a. Collect the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT in section I of the substation at the load end;

(1) The incoming circuit breaker 1DL at the load end of the No. 1 power line is in the closing position;

(2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT of the first section of the load end, two values are satisfied between 0.45E _ab and 0.635E _ab between 0.9E _ab to 1.1E _ab ;

If the above conditions are all satisfied, it means that the voltage of the busbar of the first section of the substation at the load end is abnormal (hereinafter referred to as the abnormal voltage);

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation;

(1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The circuit breaker 4DL at the power end of Line 1 is in the closed position;

All of the above conditions are satisfied, indicating that the voltage of the busbar of the substation on the upper power supply side is normal; through the optical fiber channel of the optical fiber differential protection of the power line No. 1, the above-mentioned voltage normal signal is sent to the line protection of the load substation of the No. 1 line. disconnection protection in the line protection;

When the voltage of the corresponding busbar of the power supply side substation is normal, and the busbar voltage of the first section of the load side substation is abnormal, then identify and judge that the No. 1 power supply line is disconnected, and the disconnection protection in the line protection of the load side substation, jump to the load side of the No. 1 power supply line. The circuit breaker 1DL is automatically activated by the substation at the load end, and the circuit breaker 2DL or 3DL of the backup power supply is activated and closed, so that the transformer that has lost power can be restored to the backup power supply line for power supply; at the same time, the line 1 disconnection alarm is activated;

1.4 Judging the conditions for the disconnection of Line 2 to jump the circuit breaker 2DL on the load side of the disconnected line 2 and the self-switching start-up circuit breaker 1DL or 3DL from the load side, and to activate the disconnection alarm of Line 2:

a. Collect secondary AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of busbar PT in section II of the substation at the load end;

(1) The incoming circuit breaker 2DL at the load end of the No. 2 power line is in the closing position;

(2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the second section busbar PT at the load end, two values are within the range of 0.45E _ab to 0.635E _ab between 0.9E _ab to 1.1E _ab ;

If the above conditions are met, it means that the voltage of the busbar in section II of the substation at the load end is abnormal;

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation;

(1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The circuit breaker 5DL at the power end of Line 2 is in the closed position;

All of the above conditions are met, indicating that the voltage of the corresponding busbar of the upper substation is normal; through the optical fiber channel of the optical fiber differential protection of the No. 2 power supply line, the above-mentioned voltage normal signal is sent to the line protection of the load substation of the No. 2 line. disconnection protection;

When the received bus voltage of the upper-level substation is normal, and the bus voltage of the second section of the substation at the load end is abnormal, then identify and judge that the No. 2 power supply line is disconnected, and the disconnection protection in the line protection of the upper-level substation, skip the load of the No. 2 power supply line. The side circuit breaker 2DL is automatically activated by the substation at the load end, and the backup power circuit breaker 1DL or 3DL is activated and closed, so that the transformer that has lost power can be restored to the backup power line for power supply; at the same time, the No. 2 line disconnection alarm is activated.

The object of the present invention can also be further realized through the following technical measures:

The above-mentioned disconnection protection method of comparing the line voltage on both sides of the line and the automatic switching of the equipment is applied to the method of the neutral point of the transformer is not grounded or grounded through the arc suppression coil and the small resistance grounding system.

In the above-mentioned comparison of the line voltage on both sides of the line and the disconnection protection method of the standby automatic switching, the rated line voltage value E _ab of the PT secondary side is 100V.

In the above-mentioned comparison of the line voltage on both sides of the line and the disconnection protection method of the standby automatic switching, t1 should avoid the three-phase non-period time when the circuit breaker is closed, and take 0.1 to 0.2 seconds.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention makes full use of the fault characteristics of the secondary voltage of the substation bus PT at the power supply end and the load end when the single-phase line is disconnected, and compares the busbar voltages at both ends of the line to identify the single-phase disconnection of the line and jump the circuit breaker or load at the power supply side. Side circuit breaker, simple and easy.

2. The present invention adopts the transmission of the voltage information on both sides of the line through the line optical fiber channel, compares the line voltage on both sides of the line to identify the line disconnection, jumps the circuit breaker on the power supply side or the circuit breaker on the load side, and then the substation at the load end is prepared for self-switching action and starts. The relay protection scheme of tripping the incoming circuit breaker and closing the standby power supply circuit breaker to restore the power supply to the standby power supply can effectively prevent the impact of the transformer phase-lost power supply on the power grid and the load power supply, which is beneficial to Safe and stable operation of the power grid.

3. The method of the present invention is implemented by using line protection devices on both sides of the line, and no additional hardware equipment is required.

Description of drawings

Figure 1 is a schematic diagram of the primary system that is not grounded or grounded through the arc suppression coil at the 35kV side of the upper substation;

Figure 2 is a vector diagram of the 35kV busbar voltage on the power supply side that is not grounded or grounded by the arc suppression coil;

Figure 3 is a vector diagram of the 35kV busbar voltage on the ungrounded or grounded load side through the arc suppression coil;

Figure 4 is a schematic diagram of the primary system where the 35kV line is disconnected and the disconnection on the load side is grounded;

Fig. 5 is the voltage vector diagram of the 35kV busbar on the grounded load side at the disconnection of the load side;

Figure 6 is a schematic diagram of the primary system where the 35kV line is disconnected and the disconnection on the power supply side is grounded;

Fig. 7 is the voltage vector diagram of the 35kV busbar voltage on the grounded power supply side at the disconnection of the power supply side;

Figure 8 is a vector diagram of the 35kV busbar voltage on the grounded load side at the disconnection of the power supply side;

Figure 9 is a schematic diagram of the primary system of the 35kV side of the upper-level substation grounded by resistance;

Figure 10 is a vector diagram of the 35kV busbar voltage on the 35kV side of the upper-level substation through the resistance grounding power supply side;

Figure 11 is a vector diagram of the 35kV busbar voltage on the 35kV side of the upper-level substation on the load side via resistance grounding;

Figure 12 is a schematic diagram of the primary system for the 35kV disconnection and the grounding at the disconnection on the load side;

Figure 13 is a voltage vector diagram of the 35kV busbar on the grounded load side at the disconnection of the load side;

Figure 14 is a schematic diagram of the primary system where the 35kV line is disconnected and the disconnection on the power supply side is grounded;

Fig. 15 is the principle diagram of the 35kV single-phase disconnection protection of the power supply side comparing the line voltage on both sides and the automatic switching of the backup according to the present invention;

Fig. 16 is the principle diagram of the 35kV single-phase disconnection protection of the load side comparing the line voltage on both sides and the backup and automatic switching in accordance with the present invention;

Figure 17 is the main wiring diagram of the single busbar segment of the 35kV substation;

Figure 18 is the primary main wiring diagram of the bridge in the 35kV substation;

Figure 19 is the primary wiring diagram of the enlarged inner bridge of the 35kV substation;

Figure 20 shows the primary wiring of the 35kV line substation in the 35kV substation.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

First, take the 35kV line disconnection as an example to analyze the fault characteristics (the 3, 6, 10, 20, and 66kV lines are the same):

1.1 Ungrounded or grounded system via arc suppression coil

1.1.1 35kV line disconnection

Figure 1 is a schematic diagram of a 35kV line-break primary system, taking the A-phase short line as an example. The 35kV side of the upper substation is not grounded or grounded through the arc suppression coil, and the 35kV neutral point of the 35kV transformer substation on the load side is not grounded. Assume that the power supply potentials on the 35kV side of the upper-level substation are E _A , E _B , and E _C respectively, and UN is the 35kV neutral point voltage of the transformer in the power _- supply side substation. If the line is broken at α, the capacitance to ground from the broken line to the bus side of the upper-level substation is: αC, the ground-to-ground capacitance of the 35kV bus from the disconnection point to the load-side substation is (1-α)C.

1. Analysis of the busbar voltage on the power supply side

According to the analysis, the busbar voltage on the 35kV side of the upper substation is:

分别为电源侧35kV母线A1B1线电压、B1C1线电压、C1A1线电压。

为上级变电站35kV侧电源线电压(其大小相等)。电源侧35kV母线电压向量图见图2，如图2可知，当发生35kV线路A相断线时，上级变电站35kV母线三相线电压不变，保持对称。图中α在0～1间变化，0点在如图2中0_α＝0至0_α＝1间变化，当α＝1时，0点在0_α＝1点处，当α＝0时，0在0_α＝0(下同)。In formula (1),

They are the 35kV bus A1B1 line voltage, B1C1 line voltage, and C1A1 line voltage on the power supply side, respectively.

It is the voltage of the power supply line on the 35kV side of the upper-level substation (its size is equal). The voltage vector diagram of the 35kV busbar on the power supply side is shown in Figure 2. As can be seen from Figure 2, when the 35kV line A-phase disconnection occurs, the three-phase line voltage of the 35kV busbar in the upper substation remains unchanged and remains symmetrical. In the figure, α varies between 0 and 1, and the 0 point varies from 0 _α=0 to 0 _α=1 in Figure 2. When α=1, the 0 point is at 0 _α=1 point, and when α=0 , 0 is at 0 _α=0 (the same below).

2. Analysis of load side busbar voltage

The analysis of the 35kV load side busbar voltage is:

分别为负荷侧35kV母线A2B2线电压、B2C2线电压、C2A2线电压，负荷侧35kV母线电压向量图见图3。(2) In formula,

They are the A2B2 line voltage, B2C2 line voltage, and C2A2 line voltage of the 35kV busbar on the load side, respectively. The voltage vector diagram of the 35kV busbar on the load side is shown in Figure 3.

为

与

方向相反，大小为

It can be seen from Figure 3 that when the 35kV line is disconnected, the load side

for

and

In the opposite direction, the size is

1.1.2 The 35kV line is disconnected and the disconnection on the load side is grounded

Figure 4 is a schematic diagram of the 35kV disconnection and the grounded primary system at the disconnection on the load side, taking the A-phase short line as an example. The 35kV side of the upper substation is not grounded, and the 35kV neutral point of the 35kV transformer substation on the load side is not grounded. Assume that the power supply potentials on the 35kV side of the upper-level substation are EA, EB, and _{E C} respectively, and UN is the 35kV neutral point voltage of the transformer in the power _- supply side substation _. The 35kV busbar-to-ground capacitance of the side substation is (1-α)C.

1. Analysis of the busbar voltage on the power supply side

The analysis is the same as 1.1.1.

2. Analysis of load side busbar voltage

The analysis of the 35kV load side busbar voltage is:

The 35kV bus voltage vector diagram on the load side is shown in Figure 5.

等于

随着断线靠近电源侧母线距离的不同，α在0～1间变化，同时

在

至0间变化，0点在如图5中0_α＝0至0_α＝1间变化，

的大小在

变化至E_B间变化，同时

的大小

变化至E_C间变化。It can be seen from Figure 5 that when the 35kV line is disconnected and the disconnection on the load side is grounded,

equal

As the distance between the disconnection and the busbar on the power supply side is different, α varies between 0 and 1, and at the same time

exist

change from 0 to 0, and the 0 point changes from 0 _α=0 to 0 _α=1 as shown in Figure 5,

size in

change to _EB , while

the size of

Variation between _EC and EC.

1.1.3 The 35kV line is disconnected and the disconnection on the power supply side is grounded

Figure 6 is a schematic diagram of the primary system where the 35kV line is disconnected and the disconnection on the power supply side is grounded, taking the A-phase short line as an example. The 35kV side of the upper substation is not grounded, and the 35kV neutral point of the 35kV transformer substation on the load side is not grounded. Assume that the power supply potentials on the 35kV side of the upper-level substation are EA, EB, and _{E C} respectively, and UN is the 35kV neutral point voltage of the transformer in the power _- supply side substation _. The 35kV busbar-to-ground capacitance of the side substation is (1-α)C.

1. Analysis of the busbar voltage on the power supply side

Analyze the busbar voltage on the 35kV side of the superior substation:

The 35kV busbar voltage vector diagram on the power supply side is shown in Figure 7.

It can be seen from Figure 7 that when the 35kV line is disconnected and the power supply side is grounded, the three line voltages remain unchanged and symmetrical.

2. Analysis of load side busbar voltage

The analysis of the 35kV load side busbar voltage is:

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

为

与

方向相反，大小为

When the 35kV line is disconnected, the load side

for

and

In the opposite direction, the size is

1.2 Earthing system via resistance

1.2.1 35kV line disconnection

Figure 9 is a schematic diagram of a 35kV line-break primary system, taking the A-phase short line as an example. The 35KV power supply system of the substation on the 35kV side of the upper substation is grounded by resistance (R is generally 10, 20, 100Ω). Assume that the power supply potentials on the 35kV side of the upper-level substation are E _A , E _B , and E _C respectively, and UN is the 35kV neutral point voltage of the transformer in the power _- supply side substation. If the line is broken at α, the capacitance to ground from the broken line to the bus side of the upper-level substation is: αC, the ground-to-ground capacitance of the 35kV bus from the disconnection point to the load-side substation is (1-α)C.

1. Analysis of the busbar voltage on the power supply side

According to the analysis, the busbar voltage on the 35kV side of the upper substation is:

分别为电源侧35kV母线A1B1线电压、B1C1线电压、C1A1线电压。电源侧35kV母线电压向量图见图10。In formula (6),

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

As can be seen in Figure 10, when the 35kV line A-phase disconnection occurs, the three-phase line voltage of the 35kV busbar in the upper substation remains unchanged and remains symmetrical. As the distance between the disconnection and the busbar on the power supply side is different, the 0 point varies from 0 _α=0 to 0 _α=1 as shown in Figure 10. When α=1, the 0 point is at 0 _α=1 point, and when α= When it is 0, 0 is at 0 _α=0 (the same below), and U _N changes between ωCE _A R and 0 at the same time (cable line capacitance C is generally ≤ 0.55μF, overhead line is even smaller, so U _N is a very small value , according to the grounding resistance of 20Ω, C is 0.55μF, U _N is 3.45 ^-3 E _A , so it can be ignored).

2. Analysis of load side busbar voltage

The analysis of the 35kV load side busbar voltage is:

分别为负荷侧35kV母线A2B2线电压、B2C2线电压、C2A2线电压，负荷侧35kV母线电压向量图见图11。In formula (7),

They are the A2B2 line voltage, B2C2 line voltage, and C2A2 line voltage of the 35kV busbar on the load side, respectively. The voltage vector diagram of the 35kV busbar on the load side is shown in Figure 11.

为

与

方向相反，大小为

It can be seen from Figure 11 that when the 35kV line is disconnected, the load side

for

and

In the opposite direction, the size is

1.2.2 The 35kV line is disconnected and the disconnection on the load side is grounded

Figure 12 is a schematic diagram of the 35kV disconnection and the grounded primary system at the load side disconnection, taking the A-phase short line as an example. The 35KV power supply system of the substation on the 35kV side of the upper substation is grounded by resistance. Assume that the power supply potentials on the 35kV side of the upper-level substation are EA, EB, and _{E C} respectively, and UN is the 35kV neutral point voltage of the transformer in the power _- supply side substation _. The 35kV busbar-to-ground capacitance of the side substation is (1-α)C.

1. Analysis of the busbar voltage on the power supply side

The analysis is the same as 1.2.1.

2. Analysis of load side busbar voltage

The analysis of the 35kV load side busbar voltage is:

The 35kV bus voltage vector diagram on the load side is shown in Figure 13.

It can be seen from Figure 13 that when the 35kV line is disconnected and the disconnection on the load side is grounded, U _B2C2 is equal to E _BC , and the distance between the disconnection and the busbar on the power supply side varies. Since _UN is negligible, the sizes of U _A2B2 and U _C2A2 are approximately equal to E _B and E _C .

1.2.3 The 35kV line is disconnected and the disconnection on the power supply side is grounded

Figure 14 is a schematic diagram of the primary system where the 35kV line is disconnected and the disconnection on the power supply side is grounded, taking the A-phase short line as an example. The 35KV power supply system of the substation on the 35kV side of the upper substation is grounded by resistance. Assume that the power supply potentials on the 35kV side of the upper-level substation are EA, EB, and _{E C} respectively, and UN is the 35kV neutral point voltage of the transformer in the power _- supply side substation _. The 35kV busbar-to-ground capacitance of the side substation is (1-α)C.

When the line is broken and grounded on the system side, it is a single-phase grounding short-circuit fault, so the zero-sequence current protection action of the system substation line trips, and the reclosing can not be reclosed.

3~66kV line disconnection fault characteristic analysis:

For the ungrounded, grounded by arc suppression coil, and grounded by resistance system, the 35kV line is disconnected, the 35kV line is disconnected and the load-side disconnection is grounded, and the 35kV line is disconnected and the power-side disconnection is grounded. The voltage is unchanged and the line voltage is symmetrical (for the resistance grounding system, when the line is broken and grounded on the system side, it is a single-phase grounding short-circuit fault, and the line zero-sequence current protection will trip).

等于

与

方向相反，大小为

对于35kV线路断线且负荷侧断线处接地情况，

等于

随着断线靠近电源侧母线距离的不同，α在0～1间变化，

的大小在

变化至E_B间变化，同时

的大小在

变化至E_C间变化。Since the 35kV line is disconnected and the power-side disconnection is grounded, U _N can be ignored. Therefore, for the two cases of 35kV line disconnection and 35kV line disconnection and grounding at the power-side disconnection, the busbar voltage on the load side, the load side

equal

and

In the opposite direction, the size is

For the case where the 35kV line is disconnected and the load-side disconnection is grounded,

equal

As the distance between the disconnection and the busbar on the power supply side is different, α varies between 0 and 1.

size in

change to _EB , while

size in

Variation between _EC and EC.

In the same way, when the 3~66kV line is disconnected, the busbar voltage on both sides of the line has the same fault characteristics.

The technical scheme of the inventive method is provided below:

The transmission and distribution network applied by the method of the present invention is 35kV substation 35kV single bus segment primary main connection (including 35kV single bus primary main connection), 35kV inner bridge connection (as shown in Figure 18), 35kV expanded inner bridge Wiring (as shown in Figure 19), the primary main wiring of the 35kV line transformer group in the 35kV substation (as shown in Figure 20). Taking the 35kV substation as an example of the 35kV single bus segmented primary wiring, the protection methods for other primary primary wiring are similar. The general structure of the 35kV single bus segment primary wiring of the 35kV substation is as follows: No. 1 power supply incoming branch equipment and No. 2 power incoming branch equipment are respectively connected to the 35kV I-section busbar and the 35kV II-section busbar; 35kV I-section busbar and II-section busbar There is a sectional circuit breaker 3DL in between, and the sectional current transformer CT is connected in series with the sectional circuit breaker 3DL; the circuit breaker 1DL is installed in the interval equipment of the incoming branch circuit of No. 1 power supply, and the circuit breaker is installed in the interval equipment of the incoming branch circuit of No. 2 power source. 2DL, the No. 1 power supply incoming branch and No. 2 power incoming branch are respectively connected with current transformers CT1 and CT2 in series; in addition, the 35kV Section I bus is also connected with No. 1 transformer branch and 35kV voltage transformer PT1; 35kV Section II The busbar is also connected with No. 2 transformer branch and 35kV voltage transformer PT2. There is a circuit breaker 4DL on the power supply side of the No. 1 power incoming line, and a circuit breaker 5DL on the power supply side of the No. 2 power incoming line. 35kV PT3 is connected to the 35kV busbar of the power supply end of the No. 1 power supply incoming line, and 35kV PT4 is connected to the 35kV busbar of the power supply end of the No. 2 power supply incoming line. The 35kV line is provided with optical fiber channel and line optical fiber differential protection.

For the above-mentioned 35kV single busbar segmented primary wiring, the upper substation implements the transmission of the voltage information on both sides of the line through the 35kV line fiber optic channel, compares the line voltages on both sides of the line to identify the 35kV line disconnection, and trips the 35kV line power-side circuit breaker or load-side circuit breaker , The 35kV substation at the load end is prepared with a self-recovery power supply scheme to meet the on-site operation requirements.

As shown in Figures 15 and 16, take the 35KV line as an example. The invention compares the disconnection protection method of the line voltage on both sides of the line and the automatic switching of the backup, including:

1. Judging the conditions for 35kV line disconnection to start tripping the 35kV line power-side circuit breaker or load-side circuit breaker and the conditions for restoring the power supply by the 35kV backup self-switching

1.1 Judging that No. 1 35kV line is disconnected, jump the circuit breaker 4DL on the power supply side of the No. 1 35kV disconnected line, and the 35kV standby power supply circuit breaker at the load end is switched on and off, and the standby power circuit breaker 2DL or 3DL, and activate the No. 1 35kV line disconnection alarm condition

a. Collect the voltage value U _ab , the voltage value U _bc , and the voltage value U _ca of the CA line of the PT secondary AB line of the 35kV substation at the load end.

(1) The 35kV incoming circuit breaker 1DL at the load end of No. 1 35kV power line is in the closing position;

(2) Three line voltages of AB line voltage U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of the 35kV I-section busbar PT at the load end, which satisfy the two are between 0.45E _ab and 0.635E _ab , One is between 0.9E _ab to 1.1E _ab .

The above conditions are all satisfied, which means that the voltage of the busbar of the first section of the 35kV substation at the load end is abnormal (hereinafter referred to as the abnormal voltage). The signal is sent to the 35kV disconnection protection of the 35kV line protection at the power supply end of the No. 1 35kV line in the superior substation.

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary 35kV busbar PT in the upper-level substation.

(1) The voltage value U _ab of the 35kV busbar PT secondary AB line corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the 35kV busbar PT secondary BC line at the power supply end is greater than or equal to 0.9E _ab and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line corresponding to the 35kV busbar PT at the power supply end is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The 35kV line circuit breaker 4DL at the power end of No. 1 35kV line is in the closing position.

All of the above conditions are satisfied, which means that the three line voltages of the 35kV busbar of the upper power supply side substation are symmetrical (the amplitudes are basically equal), that is, the power supply side voltage is normal (referred to as normal voltage).

When the voltage of the corresponding 35kV busbar of the power supply side substation is normal, and the received busbar voltage of the first section of the 35kV substation at the load end is abnormal, then identify and judge the disconnection of the No. Jump the circuit breaker 4DL on the power side of the No. 1 35kV power line. Since the No. 1 35kV power line loses power, the 35kV substation at the load end will automatically switch on the 35kV power supply, start to trip the No. 1 35kV power incoming circuit breaker 1DL, and close the standby power circuit breaker 2DL or 3DL, so that the transformer that has lost power is restored to Power is supplied on the backup power line. At the same time, start the No. 1 35kV line disconnection alarm.

1.2 Judging the condition of No. 2 35kV line breakage jumping No. 2 35kV line power-side circuit breaker 5DL and the 35kV self-switching start of the load end to close the standby power circuit breaker 1DL or 3DL, and starting the No. 2 35kV line disconnection alarm conditions

a. Collect the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the 2nd section bus bar of the 35kV substation at the load end.

(1) The 35kV incoming circuit breaker 2DL at the load end of No. 2 35kV power line is in the closing position;

(2) Three line voltages of AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of the 35kV II section busbar PT at the load end, which satisfy the two are between 0.45E _ab and 0.635E _ab , one at 0.9E _ab to 1.1E _ab ;

If the above conditions are met, it means that the busbar voltage of the 35kV substation section II at the load end is abnormal. Through the optical fiber channel of the optical fiber differential protection of the No. 2 35kV power supply line, the above voltage and the abnormal signal of the busbar voltage of the second section of the 35kV substation at the load end are sent to the upper-level substation No. 1. 35kV disconnection protection in the 35kV line protection of the power supply end of the 35kV line.

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary 35kV busbar PT in the upper-level substation.

(1) The voltage value U _ab of the 35kV busbar PT secondary AB line corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the 35kV busbar PT secondary BC line at the power supply end is greater than or equal to 0.9E _ab and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line corresponding to the 35kV busbar PT at the power supply end is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The 35kV circuit breaker 5DL at the power end of the No. 2 35kV line is in the closing position.

All the above conditions are satisfied, indicating that the voltage of the 35kV busbar corresponding to the upper substation is normal.

When the voltage of the 35kV busbar corresponding to the upper substation is normal, and the received voltage of the 35kV substation II busbar at the load end is abnormal, then identify and judge that the No. 2 35kV power line is disconnected, and the 35kV disconnection protection in the 35kV line protection of the upper substation, Jump off the circuit breaker 5DL on the power side of the No. 2 35kV power line. Since the No. 2 35kV power line loses power, the 35kV backup at the load end 35kV substation will operate automatically, start to trip the No. 2 35kV power incoming circuit breaker 2DL, and close the backup power circuit breaker 1DL or 3DL, so that the transformer that has lost power is restored to Power is supplied on the backup power line. At the same time start the No. 2 35kV line disconnection alarm.

1.3 Judging that the No. 1 35kV line is disconnected, jump the load side circuit breaker 1DL of the No. 1 35kV disconnected line, and the 35kV standby power supply circuit breaker at the load end will be switched to 2DL or 3DL, and activate the No. 1 35kV line disconnection alarm condition

a. Collect the voltage value U _ab , the voltage value U _bc , and the voltage value U _ca of the CA line of the PT secondary AB line of the 35kV substation at the load end.

(1) The 35kV incoming circuit breaker 1DL at the load end of No. 1 35kV power line is in the closing position;

(2) Three line voltages of AB line voltage U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of the 35kV I-section busbar PT at the load end, which satisfy the two are between 0.45E _ab and 0.635E _ab , One is between 0.9E _ab to 1.1E _ab .

The above conditions are all satisfied, which means that the voltage of the busbar of the first section of the 35kV substation at the load end is abnormal (hereinafter referred to as the abnormal voltage).

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary 35kV busbar PT in the upper-level substation.

(1) The voltage value U _ab of the 35kV busbar PT secondary AB line corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the 35kV busbar PT secondary BC line at the power supply end is greater than or equal to 0.9E _ab and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line corresponding to the 35kV busbar PT at the power supply end is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The 35kV line circuit breaker 4DL at the power end of No. 1 35kV line is in the closing position.

All the above conditions are satisfied, indicating that the voltage of the 35kV busbar of the substation on the upper power supply side is normal. Through the optical fiber channel of the optical fiber differential protection of the No. 1 35kV power line, the above-mentioned voltage normal signal is sent to the 35kV disconnection protection of the 35kV line protection of the load 35kV substation of the No. 1 35kV line.

When it is received that the voltage of the 35kV busbar corresponding to the power supply side substation is normal, and the busbar voltage of the first section of the 35kV substation at the load end is abnormal, then identify and judge that the No. 1 35kV power supply line is disconnected, and the 35kV disconnection in the 35kV line protection of the 35kV substation at the load end is identified and judged. Line protection, jump the load side circuit breaker 1DL of No. 1 35kV power supply line, and the 35kV backup self-switching action of the 35kV substation at the load end will start and close the backup power circuit breaker 2DL or 3DL, so that the transformer that has lost power will be restored to the backup power supply line. At the same time, start the No. 1 35kV line disconnection alarm.

1.4 Judging the conditions for the No. 2 35kV line breakage to jump the No. 2 35kV line breaker 2DL on the load side and the 35kV self-switching start-up and standby power circuit breaker 1DL or 3DL at the load end, and to activate the No. 2 35kV line disconnection alarm conditions

a. Collect the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the 2nd section bus bar of the 35kV substation at the load end.

(1) The 35kV incoming circuit breaker 2DL at the load end of No. 2 35kV power line is in the closing position;

(2) Three line voltages of AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of the 35kV II section busbar PT at the load end, which satisfy the two are between 0.45E _ab and 0.635E _ab , one at 0.9E _ab to 1.1E _ab ;

If the above conditions are satisfied, it means that the busbar voltage of section II of the 35kV substation at the load end is abnormal.

b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary 35kV busbar PT in the upper-level substation.

(1) The voltage value U _ab of the 35kV busbar PT secondary AB line corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(2) The voltage value U _bc of the 35kV busbar PT secondary BC line at the power supply end is greater than or equal to 0.9E _ab and less than or equal to 1.1E _ab ;

(3) The voltage value U _ca of the secondary CA line corresponding to the 35kV busbar PT at the power supply end is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ;

(4) The 35kV circuit breaker 5DL at the power end of the No. 2 35kV line is in the closing position.

All the above conditions are satisfied, indicating that the voltage of the 35kV busbar corresponding to the upper substation is normal. Through the optical fiber channel of optical fiber differential protection of No. 2 35kV power line, the above-mentioned voltage normal signal is sent to the 35kV disconnection protection in the 35kV line protection of the load 35kV substation of No. 2 35kV line.

When the received 35kV busbar voltage of the upper-level substation is normal, and the bus voltage of the second section of the 35kV substation at the load end is abnormal, then identify and judge that the No. 2 35kV power supply line is disconnected, and the 35kV disconnection protection in the 35kV line protection of the upper-level substation will jump. The load side circuit breaker 2DL of No. 2 35kV power supply line is activated by the 35kV standby power supply of the 35kV substation at the load end, and the standby power supply circuit breaker 1DL or 3DL is activated and closed, so that the transformer that has lost power can be restored to the standby power supply line to supply power. At the same time start the No. 2 35kV line disconnection alarm.

1.5 In the above 1.1 to 1.4:

(1) The method of the present invention can be applied to the ungrounded neutral point of the transformer or the grounding method of the arc suppression coil and the small resistance grounding system.

(2) The reason for adopting the circuit breakers 1DL or 2DL and 4DL or 5DL on both sides of the 35kV power supply line in the closing position is: when a power supply line has a 35kV substation at the load end, the bus voltage of the power line is far away from the power line. You can also feel the information of line disconnection, which will interfere with the closing standby power circuit breaker prepared for automatic switching; in addition, when using line PT, the power incoming line may have other 35kV substations at the load end. 35kV substation power inlet circuit breaker trips slowly or refuses to trip, which will also interfere with the closed standby power supply circuit breaker for self-switching, which may cause the self-switching to fail to operate. The logic can be further optimized by using the condition of the 35kV mains incoming circuit breaker in the closed position.

(3) E _ab is the rated line voltage value of the power supply, considering the grid voltage fluctuation, it is considered as ±10% of the actual grid rated voltage value, among which: when the rated line voltage value is greater than or equal to the rated line voltage value, it is considered as 0.9 times the rated grid voltage value; less than or equal to the rated voltage value The line voltage value is considered as 1.1 times the rated voltage value of the grid.

1.6 After identifying the disconnection of the 35kV line, the tripping plan: (1) trip the circuit breaker on the power side of the disconnected line; (2) trip the circuit breaker on the load side of the disconnected line; (3) disconnect the circuit breaker on both sides of the disconnected line jump out together.

1.7 For the busbar load of the load-side substation operating in the open-phase operation due to disconnection, the power-side or load-side circuit breaker of the disconnected line is automatically transferred by the standby switch, and the standby power circuit breaker is closed to automatically transfer the load to restore the load to Backup line power. If the 35kV substation adopts the primary main wiring of the 35kV line substation, the power supply will be restored by the self-introduction of the medium and low voltage side backup of the load side substation.

2. The 35kV neutral point operation mode of the main transformer on the bus of Section I or Section II of the 35kV substation at the load end is ungrounded; the 35kV side is equipped with a 35kV automatic switching device. The 35kV lines of No. 1 and No. 2 power supplies must be provided with optical fiber channel and line optical fiber differential protection.

3. The method of the present invention can be implemented in a separate 35kV line disconnection protection device of a 35kV substation at the power supply end or the load end or in a 35kV line protection device. Implemented in 35kV line protection devices, its advantages do not require additional hardware equipment.

4. The PT secondary setting value of the 35kV section I busbar or section II busbar disconnection phase of the 35kV substation at the load end is:

PT二次额定线电压值为100V，即≥45V且≤63.5V；一个取大于等于额定线电压值的90％，且小于等于额定线电压值的110％，即≥90V且≤110V。The setting values of the three line voltages of the 35kV bus PT secondary AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca are: two are greater than or equal to 45% of the rated line voltage value (0.9 *0.5), and less than or equal to the rated line voltage value

PT secondary rated line voltage value is 100V, that is, ≥45V and ≤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, that is, ≥90V and ≤110V.

5. When the 35kV line is disconnected, the PT secondary setting value of the 35kV busbar of the 35kV substation at the power supply end is:

The setting value of the three line voltages of the 35kV busbar PT secondary AB line voltage U _ab , BC line voltage U _bc , CA line voltage U _ca three line voltages: PT secondary rated line voltage is 100V, whichever is greater than or equal to the rated value 90% of the line voltage value, and less than or equal to 110% of the rated line voltage value, that is, ≥90V and ≤110V.

6. The method of the present invention, the setting value of the time in the single-phase disconnection relay protection method of the 35kV substation at the load end with self-switching and power supply recovery:

t1: The three-phase different time when the switch is closed, take 0.1 to 0.2 seconds;

7. The scheme of the present invention can meet the following primary main wiring: (1) 35kV single bus segment primary wiring in 35kV substation; (2) 35kV inner bridge primary main wiring in 35kV substation; (3) 35kV expanded primary main wiring in 35kV substation; ( 4) Primary main wiring of 35kV line transformer group in 35kV substation; (5) Other primary main wiring.

8. For the 35kV line with branch wiring, it is necessary to implement the 35kV disconnection protection between the power supply side substation and each load side substation with the corresponding relationship between the power supply side and the load side substation.

9. Compare the busbar voltage on both sides of the line. The invention scheme can also be used in the case of disconnection of a 110kV line powered by a single power supply.

An embodiment of the method of the present invention is given below (taking Fig. 17 and the circuit breaker on the power source side as an example):

Operation mode 1

In this operation mode, the No. 2 power circuit breaker 2DL and the sectional circuit breaker 3DL operate, and the No. 1 power circuit breaker 1DL is hot standby, that is, the No. 1 power circuit breaker 1DL is in the open position.

Taking the A-phase disconnection as an example, the B-phase or C-phase disconnection is similar. When the A-phase single-phase disconnection of No. 2 35kV power supply line fails, the voltage of the second section busbar of the load-side substation feels abnormal operation, but the voltage of the 35kV busbar PT secondary line of the power-side substation is normal, which satisfies the requirements of the No. 2 35kV power line single-phase line. For the condition of phase disconnection, after delay t1, the 35kV line disconnection protection in the line protection of the power supply end will trip the circuit breaker 5DL on the power supply side of the No. 2 35kV power supply line. Since the No. 2 35kV power supply line loses power, the 35kV backup at the load end 35kV substation operates automatically, trips the No. 2 35kV power circuit breaker 2DL, 35kV starts the No. 1 35kV backup power circuit breaker 1DL and closes, so that the transformer that has lost power is restored to standby Power supply on No. 1 35kV power line. At the same time, the single-phase disconnection signal of No. 2 35kV power line is issued.

Operation mode 2

In this operation mode, the No. 1 power circuit breaker 1DL and the sectional circuit breaker 3DL operate, and the No. 2 power circuit breaker 2DL is in hot standby, that is, the No. 2 power circuit breaker 2DL is in the open position.

Taking the A-phase disconnection as an example, the B-phase or C-phase disconnection is similar. When the A-phase single-phase disconnection of No. 1 35kV power supply line fails, the voltage of the first section of the substation at the load end will feel abnormal operation, but the voltage of the PT secondary line of the 35kV busbar at the power end substation is normal, which meets the requirements of the single-phase line of the No. 1 35kV power supply line. The condition of disconnection, after the delay t1, the disconnection protection of the 35kV line in the line protection of the power supply side will trip the circuit breaker 4DL on the power supply side of the No. 1 35kV power supply line. Since the No. 1 35kV power line loses power, the 35kV backup at the load end 35kV substation operates automatically, trips the No. 1 35kV power circuit breaker 1DL, and starts the No. 2 35kV backup power circuit breaker 2DL to close, so that the transformer that has lost power is restored to the standby 2 No. 35kV power supply line power supply. At the same time, the single-phase disconnection signal of No. 1 35kV power line is issued.

Operation mode 3

In this operation mode, the No. 1 power circuit breaker 1DL and the No. 2 power circuit breaker 2DL operate, and the sectional circuit breaker 3DL is in hot standby, that is, the sectional circuit breaker 3DL is in the opening position.

No. 1 35kV power line single-phase disconnection fault

Taking the A-phase disconnection as an example, the B-phase or C-phase disconnection is similar. When the A-phase single-phase disconnection of No. 1 35kV power line fails, the voltage of the first section of the substation at the load end feels abnormal operation, but the voltage of the PT secondary line of the 35kV bus of the power substation is normal, which meets the requirements of the single-phase No. 1 35kV power line. The condition of disconnection, after the delay t1, the disconnection protection of the 35kV line in the line protection of the power supply side will trip the circuit breaker 4DL on the power supply side of the No. 1 35kV power supply line. Since the No. 1 35kV power line loses power, the 35kV backup of the 35kV substation at the load end operates automatically, trips the No. 1 35kV power incoming circuit breaker 1DL, and starts the 35kV standby power circuit breaker 3DL to close, so that the transformer that has lost power is restored to the standby 2 No. 35kV power supply line power supply. At the same time, the single-phase disconnection signal of No. 1 35kV power line is issued.

No. 2 35kV power line single-phase disconnection fault

Taking the A-phase disconnection as an example, the B-phase or C-phase disconnection is similar. When the A-phase single-phase disconnection of No. 2 35kV power supply line fails, the voltage of the second section of the load-side substation busbar feels abnormal operation, but the voltage of the 35kV busbar PT secondary line of the power-side substation is normal, which meets the requirements of the No. 2 35kV power supply line single-phase The condition of disconnection, after the delay t1, the disconnection protection of the 35kV line in the line protection of the power supply end will trip the circuit breaker 5DL on the power supply side of the No. 2 35kV power supply line. Since the No. 2 35kV power line loses power, the 35kV backup of the 35kV substation at the load end operates automatically, trips the No. 2 35kV power incoming circuit breaker 2DL, and starts the 35kV standby power circuit breaker 3DL to close, so that the transformer that has lost power is restored to the standby 1 No. 35kV power supply line power supply. At the same time, the single-phase disconnection signal of No. 2 35kV power line is issued.

In addition to the above-mentioned embodiments, the present invention may also have other embodiments, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (4)

1. a disconnection protection method that compares the line voltage on both sides of the line and the automatic switching of the equipment, it is characterized in that, the method comprises the following steps: 1. Judging the conditions for line disconnection to start jumping the circuit breaker on the power side or the circuit breaker on the load side and for restoring the power supply by the standby self-switching: 1.1 Judging that the circuit breaker 4DL on the power side of the line 1 is broken and the circuit breaker 4DL on the power side of the line 1 is disconnected, and the circuit breaker 2DL or 3DL on the standby power supply is activated by the load side, and the alarm conditions for the disconnection of the line 1 are activated: a. Collect the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT in section I of the substation at the load end; (1) The incoming circuit breaker 1DL at the load end of the No. 1 power line is in the closing position; (2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT of the first section of the load end, two values are satisfied between 0.45E _ab and 0.635E _ab Between, a value is between 0.9E _ab to 1.1E _ab , E _ab is the rated line voltage value of the power supply; If the above conditions are met, it means that the voltage of the busbar of the first section of the substation at the load end is abnormal. The above-mentioned voltage and the abnormal signal of the busbar voltage of the first section of the substation at the load end are sent to the No. 1 line of the superior substation through the optical fiber channel of the optical fiber differential protection of the No. 1 power supply line. The disconnection protection in the line protection of the power supply end; b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation; (1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (4) The circuit breaker 4DL at the power end of Line 1 is in the closed position; All of the above conditions are met, which means that the voltages of the three lines of the substation bus on the upper power supply side are symmetrical, that is, the voltage on the power supply side is normal; When the voltage of the corresponding busbar of the power-side substation is normal, and the received busbar voltage of the load-side substation I section is abnormal, then identify and judge the disconnection of the No. 1 power supply line, the disconnection protection in the line protection of the upper substation, and skip the No. 1 power supply line The circuit breaker on the power supply side is 4DL; due to the loss of power on the No. 1 power supply line, the substation at the load side will automatically switch on the power supply, start to trip the No. 1 power supply incoming circuit breaker 1DL, and close the standby power circuit breaker 2DL or 3DL, so that the transformer that loses power will be turned on. Restore the power supply to the standby power line; at the same time start the No. 1 line disconnection alarm; 1.2 Judging the conditions for the disconnection of Line 2 to jump the circuit breaker 5DL on the power supply side of the line 2 disconnection and the self-switching start-up of the load side to close the backup power circuit breaker 1DL or 3DL, and to activate the disconnection alarm of Line 2: a. Collect secondary AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of busbar PT in section II of the substation at the load end; (1) The incoming circuit breaker 2DL at the load end of the No. 2 power line is in the closing position; (2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the second section busbar PT at the load end, two values are within the range of 0.45E _ab to 0.635E _ab between 0.9E _ab to 1.1E _ab ; If the above conditions are met, it means that the voltage of the busbar of the second section of the substation at the load end is abnormal. Through the optical fiber channel of the optical fiber differential protection of the No. 2 power supply line, the above voltage and the abnormal signal of the busbar voltage of the second section of the substation at the load end are sent to the power supply of the No. 1 line of the upper substation. Disconnection protection in end line protection; b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation; (1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (4) The circuit breaker 5DL at the power end of Line 2 is in the closed position; All of the above conditions are met, indicating that the voltage of the corresponding busbar of the upper substation is normal; When the voltage of the corresponding busbar of the upper substation is normal, and the received voltage of the busbar of the second section of the substation at the load end is abnormal, then identify and judge that the No. 2 power supply line is disconnected, and the disconnection protection in the line protection of the upper substation, skip the No. 2 power supply line The circuit breaker on the power supply side is 5DL; due to the loss of power on the No. 2 power supply line, the substation at the load side will act as a backup and start to trip the circuit breaker 2DL on the incoming line of the No. 2 power supply, and close the standby power circuit breaker 1DL or 3DL to make the transformer without power supply Restore the power supply to the standby power line; at the same time start the No. 2 line disconnection alarm; 1.3 Judging the disconnection of No. 1 line, jumping the load-side circuit breaker 1DL of the No. 1 disconnected line, and the automatic switching of the load side to start the standby power circuit breaker 2DL or 3DL, and starting the No. 1 line disconnection alarm condition: a. Collect the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT in section I of the substation at the load end; (1) The incoming circuit breaker 1DL at the load end of the No. 1 power line is in the closing position; (2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the busbar PT of the first section of the load end, two values are satisfied between 0.45E _ab and 0.635E _ab between 0.9E _ab to 1.1E _ab ; If the above conditions are all satisfied, it means that the voltage of the busbar of the first section of the substation at the load end is abnormal (hereinafter referred to as the abnormal voltage); b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation; (1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (4) The circuit breaker 4DL at the power end of Line 1 is in the closed position; All of the above conditions are satisfied, indicating that the voltage of the busbar of the substation on the upper power supply side is normal; through the optical fiber channel of the optical fiber differential protection of the power line No. 1, the above-mentioned voltage normal signal is sent to the line protection of the load substation of the No. 1 line. disconnection protection in the line protection; When the voltage of the corresponding busbar of the power supply side substation is normal, and the busbar voltage of the first section of the load side substation is abnormal, then identify and judge that the No. 1 power supply line is disconnected, and the disconnection protection in the line protection of the load side substation, jump to the load side of the No. 1 power supply line. The circuit breaker 1DL is automatically activated by the substation at the load end, and the circuit breaker 2DL or 3DL of the backup power supply is activated and closed, so that the transformer that has lost power can be restored to the backup power supply line for power supply; at the same time, the line 1 disconnection alarm is activated; 1.4 Judging the conditions for the disconnection of Line 2 to jump the circuit breaker 2DL on the load side of Line 2 and the automatic switching of the load side to start the circuit breaker 1DL or 3DL on the standby power supply, and to activate the disconnection alarm of Line 2: a. Collect secondary AB line voltage value U _ab , BC line voltage value U _bc , and CA line voltage value U _ca of busbar PT in section II of the substation at the load end; (1) The incoming circuit breaker 2DL at the load end of the No. 2 power line is in the closing position; (2) Among the three line voltage values of the secondary AB line voltage value U _ab , the BC line voltage value U _bc , and the CA line voltage value U _ca of the second section busbar PT at the load end, two values are within the range of 0.45E _ab to 0.635E _ab between 0.9E _ab to 1.1E _ab ; If the above conditions are met, it means that the voltage of the busbar in section II of the substation at the load end is abnormal; b. Collect the voltage value U _ab , the voltage value U _bc of the BC line, and the voltage value U _ca of the CA line corresponding to the secondary bus PT of the upper-level substation; (1) The voltage value U _ab of the secondary AB line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (2) The voltage value U _bc of the secondary BC line of the bus PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (3) The voltage value U _ca of the secondary CA line of the busbar PT corresponding to the power supply terminal is greater than or equal to 0.9E _ab , and less than or equal to 1.1E _ab ; (4) The circuit breaker 5DL at the power end of Line 2 is in the closed position; All of the above conditions are met, indicating that the voltage of the corresponding busbar of the upper substation is normal; through the optical fiber channel of the optical fiber differential protection of the No. 2 power supply line, the above-mentioned voltage normal signal is sent to the line protection of the load substation of the No. 2 line. disconnection protection; When the received bus voltage of the upper-level substation is normal, and the bus voltage of the second section of the substation at the load end is abnormal, then identify and judge that the No. 2 power supply line is disconnected, and the disconnection protection in the line protection of the upper-level substation, skip the load of the No. 2 power supply line. The side circuit breaker 2DL is automatically activated by the substation at the load end, and the backup power circuit breaker 1DL or 3DL is activated and closed, so that the transformer that has lost power can be restored to the backup power line for power supply; at the same time, the No. 2 line disconnection alarm is activated. 2. The disconnection protection method of comparing the line voltage on both sides of the line and the automatic switching of the equipment as claimed in claim 1, it is characterized in that, it is applied to the mode that the neutral point of the transformer is not grounded or grounded through the arc suppression coil and the small resistance grounding system . 3. The disconnection protection method for comparing the line voltage on both sides of the line and the coordination of the backup and automatic switching according to claim 1, wherein the rated line voltage value E _ab of the PT secondary side is 100V. 4. The disconnection protection method of comparing the line voltage on both sides of the line and the cooperation of the standby automatic switching as claimed in claim 1, characterized in that, t1 should avoid the three-phase non-period time when the circuit breaker is closed, and take 0.1 to 0.2 seconds.

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