CN110797849A

CN110797849A - Circuit disconnection protection method for comparing voltage at two sides of circuit and matching with spare power automatic switching

Info

Publication number: CN110797849A
Application number: CN201911186657.0A
Authority: CN
Inventors: 杨茹; 李静; 陈永明; 胡航; 侯超; 宋丽; 曹斌; 汤大海; 魏刚; 王律; 徐溯
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: 2019-11-28
Filing date: 2019-11-28
Publication date: 2020-02-14
Anticipated expiration: 2039-11-28
Also published as: CN110797849B

Abstract

The invention discloses a line disconnection protection method for comparing voltages at two sides of a line and matching with a spare power automatic switch, which is a single-phase disconnection relay protection method for transmitting voltage information at two sides of the line through a 110kV line optical fiber channel, identifying 110kV line disconnection by comparing the voltages at two sides of the line, tripping a 110kV line power supply side circuit breaker or a load side circuit breaker, and recovering power supply by the spare power automatic switch of a load end 110kV transformer substation.

Description

Circuit disconnection protection method for comparing voltage at two sides of circuit and matching with spare power automatic switching

Technical Field

The invention relates to a line disconnection protection method for comparing voltages on two sides of a line and matching with a spare power automatic switching device, and belongs to the technical field of power equipment relay protection.

Background

At present, the phenomenon of 110kV line disconnection occurs in power grids in various places. The 110kV transformer powered by the 110kV line is in phase-loss operation due to line breakage, so that the three-phase voltage of the powered transformer is asymmetric, the load power supply is affected, even the 110kV neutral point of the 110kV transformer is broken down and burnt due to zero-sequence overvoltage, and the transformer is forced to be in power failure for maintenance. At present, no relay protection device specially aiming at 110kV line disconnection exists in the prior art. The invention provides a single-phase broken line relay protection method which transmits voltage information of two sides of a line through a 110kV line optical fiber channel at a load end substation, compares the voltages of the two sides of the line to identify the broken line of the 110kV line, jumps a breaker at the power supply side or a breaker at the load side of the 110kV line and recovers power supply by a backup automatic switch of the load end 110kV substation.

Disclosure of Invention

The invention aims to provide a line disconnection protection method for comparing voltages on two sides of a line and matching with a spare power automatic switch, which can be applied to a transmission and distribution network, wherein voltage information on two sides of the line is transmitted by a load end 110kV transformer substation through a 110kV line optical fiber channel, the voltage on two sides of the line is compared to identify the disconnection of the 110kV line, a 110kV line power supply side circuit breaker or a load side circuit breaker is tripped, and the power supply is recovered by the spare power automatic switch of the load end 110kV transformer substation.

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

a circuit disconnection protection method for comparing voltages on two sides of a circuit and matching with a spare power automatic switch comprises the following steps:

firstly, judging the conditions of 110kV line disconnection starting, 110kV line power supply side circuit breaker tripping and 110kV spare power automatic switching power supply recovery

1.1 judge 1 # 110kV circuit broken string jump 1 # 110kV broken string circuit power supply side circuit breaker 4DL and by load end 110kV spare power automatic switching start close stand-by power supply circuit breaker 2DL or 3DL, and start 1 # 110kV circuit broken string alarm condition:

collection load end 110kV transformer substation I section bus PT secondary A phase voltage U_aPhase U of B phase voltage_bC phase voltage U_c Open delta voltage 3U_o

(1) The PT secondary voltage value of the 110kV bus at the No. 1 110kV line open-circuit phase load end is lower than a setting value U1;

(2) the PT secondary voltage value of the 110kV bus at the 1 # 110kV line non-broken line phase 1 load end is greater than a setting value U2;

(3) the PT secondary voltage value of the 110kV bus at the No. 1 110kV line non-broken line phase 2 load end is greater than a setting value U2;

(4) the PT opening triangular secondary voltage value of the No. 1 110kV bus at the load end of the 110kV line is greater than a setting value U3;

(5) a load end 110kV line breaker 1DL of a No. 1 110kV line is at a switching-on position;

when the conditions are met, the voltage abnormality of the I-section bus of the 110kV transformer substation at the load end is represented, and the voltage abnormality signal of the I-section bus of the 110kV transformer substation at the load end are transmitted to 110kV disconnection protection in the protection of the 110kV circuit at the power end of the 1 # 110kV circuit of the 220kV transformer substation at the power end through an optical fiber channel of the 1 # 110kV power line for differential protection;

power collecting end220kV transformer substation corresponding 110kV bus PT secondary A-phase voltage U_aPhase U of B phase voltage_bC phase voltage U_c Open delta voltage 3U_o

(1) PT secondary A-phase voltage value U of 110kV bus corresponding to power supply end_aGreater than the setting value U2;

(2) PT secondary B phase voltage value U of power supply end corresponding to 110kV bus_bGreater than the setting value U2;

(3) PT secondary C-phase voltage value U of power supply end corresponding to 110kV bus_cGreater than the setting value U2;

(4) secondary voltage value 3U of power supply end corresponding to secondary opening triangle of bus PT_oIs lower than a setting value U4;

(5) a power end 110kV line circuit breaker 4DL of a No. 1 110kV line is at a switching-on position;

the conditions are all met, and the condition indicates that the 110kV bus voltage corresponding to the 110kV transformer substation at the power end is normal;

when a power supply end 220kV transformer substation corresponds to a normal 110kV bus and the received voltage of a first section of the bus of the load end 110kV transformer substation is abnormal, identifying and judging that a No. 1 110kV power supply line is broken, delaying t1, protecting the 110kV broken line in the protection of the 110kV line of the power supply end 220kV transformer substation, and tripping a No. 1 110kV power supply line power supply side circuit breaker 4 DL; because the No. 1 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching acts, the No. 1 110kV power incoming line breaker 1DL is started to be tripped out, the spare power breaker 2DL or 3DL is closed, the transformer losing the power is recovered to the spare power line to supply power, and the No. 1 110kV line disconnection alarm is started at the same time;

1.2 judge 2 # 110kV circuit broken string jump 2 # 110kV broken string circuit power supply side circuit breaker 5DL and by load end 110kV spare power automatic switching start close stand-by power supply circuit breaker 1DL or 3DL, and start 2 # 110kV circuit broken string alarm's condition:

collecting PT secondary A-phase voltage U of II-section bus of 110kV transformer substation at load end_aPhase U of B phase voltage_bC phase voltage U_cOpen delta voltage 3U_o

(1) The secondary voltage value of a No. 2 110kV line open-circuit phase load end 110kV bus PT is lower than a setting value U1;

(2) the PT secondary voltage value of the 110kV bus at the non-broken line phase 1 load end of the No. 2kV line is greater than a setting value U2;

(3) the PT secondary voltage value of the 110kV bus at the 2 # 110kV line non-broken line phase 2 load end is greater than a setting value U2;

(4) the PT opening triangular secondary voltage value of the No. 2 110kV line load end 110kV bus is greater than a setting value U3;

(5) a 110kV line breaker 1DL at a load end of a No. 2 110kV line is at a switching-on position;

when the conditions are met, indicating that the voltage of the second-section bus of the 110kV transformer substation at the load end is abnormal, transmitting the voltage and the abnormal voltage signal of the second-section bus of the 110kV transformer substation at the load end to 110kV disconnection protection in protection of the 110kV circuit at the power end of a No. 1 110kV circuit of a 220kV transformer substation at the power end through an optical fiber channel of optical fiber differential protection of the No. 2 110kV power circuit;

collecting voltage U of PT secondary A phase of 110kV bus corresponding to 220kV transformer substation at power end_aPhase U of B phase voltage_bC phase voltage U_cOpen delta voltage 3U_o

(1) The voltage value of a PT secondary A phase of a 110kV bus corresponding to a power supply end is greater than a setting value U2;

(2) the voltage value of the PT secondary B phase of the 110kV bus corresponding to the power supply end is greater than a setting value U2;

(3) the PT secondary C-phase voltage value of the power supply end corresponding to the 110kV bus is greater than a setting value U2;

(4) the secondary voltage value 3UO of the secondary opening triangle of the power supply end corresponding to the bus PT is lower than a setting value U4;

(5) a power end 110kV line circuit breaker 5DL of a No. 2 110kV line is at a switching-on position;

the conditions are all met, and the condition indicates that the voltage of a 110kV bus corresponding to a 220kV transformer substation at a power end is normal;

when the power supply end 220kV transformer substation corresponds to a normal 110kV bus and the received voltage of the II-section bus of the load end 110kV transformer substation is abnormal, identifying and judging that the No. 2 110kV power supply line is broken, delaying t1, protecting the 110kV broken line in the protection of the 110kV line of the power supply end 220kV transformer substation, and tripping a No. 2 110kV power supply line power supply side circuit breaker 5 DL; because the No. 2 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching acts, the No. 2 110kV power incoming line breaker 2DL is started to be tripped out, the spare power breaker 1DL or 3DL is closed, the transformer losing the power is recovered to the spare power line to supply power, and the No. 2 110kV line disconnection alarm is started at the same time;

1.3 judging No. 1 110kV line disconnection tripping No. 1 110kV line disconnection line load side circuit breaker 1DL and starting combined standby power supply circuit breaker 2DL or 3DL by load end 110kV backup power automatic switching, and starting No. 1 110kV line disconnection alarm condition

when the conditions are met, the abnormal voltage of the I section of the bus of the 110kV transformer substation at the load end is represented;

when the conditions are all met, the voltage of a 110kV bus corresponding to a power end 110kV transformer substation is normal, and the normal voltage signal is transmitted to 110kV disconnection protection in 110kV line protection of a No. 1 110kV transformer substation under the load of the No. 1 110kV line through an optical fiber channel of No. 1 110kV power line optical fiber differential protection;

when a 220kV transformer substation at a power end corresponds to a normal 110kV bus and the voltage of a first-section bus of a 110kV transformer substation at a load end is abnormal, identifying and judging that a 110kV power line 1 is broken, delaying t1 to protect the 110kV broken line in the 110kV transformer substation at the load end, jumping a 1DL circuit breaker at the load side of the 110kV power line 1, starting a 2DL or 3DL standby power supply circuit breaker of the 110kV transformer substation at the load end to enable a transformer losing a power supply to recover to supply power to the standby power line, and starting a 1 # 110kV line broken line alarm;

1.4 judging the 2 # 110kV line disconnection tripping 2 # 110kV line disconnection line load side circuit breaker 2DL and the load end 110kV backup power automatic switching starting combined backup power supply circuit breaker 1DL or 3DL, and starting the 2 # 110kV line disconnection alarm condition

when the conditions are met, the voltage abnormality of the second section of the bus of the 110kV transformer substation at the load end is represented;

collecting voltage U of PT secondary A phase of 110kV bus corresponding to 220kV transformer substation at power end_aPhase U of B phase voltage_bC phase voltage U_c Open delta voltage 3U_o

when the conditions are all met, the voltage of a power end 220kV transformer substation corresponding to a 110kV bus is normal, and a normal voltage signal is transmitted to 110kV disconnection protection in 110kV line protection of a No. 2 110kV line load 110kV transformer substation through an optical fiber channel of No. 2 110kV power line optical fiber differential protection;

when the received power end 220kV transformer substation corresponds to a normal 110kV bus and the voltage of a second-section bus of the load end 110kV transformer substation is abnormal, identifying and judging that a No. 2 110kV power line is broken, delaying t1, protecting the 110kV broken line in the protection of the 110kV line of the power end 220kV transformer substation, jumping a No. 2 110kV power line load side circuit breaker 2DL, starting the action of the 110kV spare power automatic switching of the load end 110kV transformer substation, switching on a spare power circuit breaker 1DL or 3DL, enabling a transformer losing a power supply to recover to the spare power line for supplying power, and starting No. 2 110kV line breakage alarm.

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

the line disconnection protection method for comparing the voltage at two sides of the line and matching the spare power automatic switching device comprises the following steps:

setting value U1 is 0.55Ea, Ea is a phase voltage value, corresponding PT secondary voltage is 58V, and 0.55Ea is 31.9V; setting value U2 is 0.9Ea, and 0.9Ea is 52.2V; setting value U3 is 0.9Eab, Eab is PT secondary opening triangle rated voltage value, 100V, 0.9Eab is 90V; the setting value U4 is between 4 and 8V.

In the line disconnection protection method for comparing the voltage at two sides of the line and the matching of the backup power automatic switching, the time t1 is defined as: three-phase different-period time when the switch is closed is avoided: taking 0.1-0.2 seconds.

The line disconnection protection method for comparing the voltage at two sides of the line and matching the spare power automatic switching is suitable for a 110kV neutral point ungrounded mode of the transformer and a 110kV neutral point grounded mode of the transformer.

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

the single-phase disconnection relay protection method is used for transmitting the voltage information of two sides of the line through the 110kV line optical fiber channel, comparing the voltages of the two sides of the line to identify the disconnection of the 110kV line, tripping the circuit breaker on the power supply side or the circuit breaker on the load side of the 110kV line, and recovering power supply through the backup power automatic switch of the 110kV transformer substation at the load end, and has the following advantages:

1. the method fully utilizes the fault characteristics of the PT secondary voltage of the 110kV bus of the power supply end and the load end substation when the 110kV line is in single-phase disconnection, compares the bus voltages at two ends of the 110kV line, and identifies the 110kV line single-phase disconnection 110kV line power supply side circuit breaker or load side circuit breaker, and is simple and easy to implement.

2. According to the invention, the voltage information at two sides of the line is transmitted through the 110kV line optical fiber channel, the voltage at two sides of the line is compared to identify the line break of the 110kV line, the 110kV line power supply side circuit breaker or the load side circuit breaker is jumped, then the load side transformer substation 110kV spare power automatic switching action starts the tripping incoming line circuit breaker and closes the spare power supply circuit breaker, so that the transformer without the power supply recovers to the relay protection scheme of the power supply on the spare power supply, the influence of the transformer phase-lacking power supply on the power grid and the load power supply can be effectively prevented, simultaneously, the 110kV transformer 110kV neutral point is prevented from being burnt, and the safe and stable operation of the.

3. The method is implemented by adopting the 110kV line protection devices on two sides of the 110kV line, and does not need to increase hardware equipment.

4. The invention is not only suitable for the mode of grounding the 110kV neutral point of the transformer, but also suitable for the mode of grounding the 110kV neutral point of the transformer.

Drawings

FIG. 1 is a first schematic diagram of a 110kV disconnection primary system;

FIG. 2 is a vector diagram of 110kV bus voltage at load side of a first vector diagram of 110kV bus voltage at line break of 110kV line;

FIG. 3 is a vector diagram of 110kV bus voltage at the power side of a first vector diagram of 110kV bus voltage at the disconnection of 110kV line;

FIG. 4 is a first schematic diagram of a 110kV disconnection and load side disconnection grounding primary system;

FIG. 5 is a vector diagram of 110kV bus voltage on the load side of a 110kV bus voltage vector diagram II when the 110kV line is disconnected;

FIG. 6 is a vector diagram of 110kV bus voltage at the power side of a 110kV bus voltage vector diagram II when the 110kV line is disconnected;

FIG. 7 is a schematic diagram II of a 110kV disconnection primary system;

FIG. 8 is a vector diagram of 110kV bus voltage on the load side of a third vector diagram of the broken bus voltage of the 110kV line;

FIG. 9 is a vector diagram of 110kV bus voltage at the power side of the third vector diagram of the broken bus voltage of the 110kV line;

FIG. 10 is a schematic diagram II of a 110kV disconnection primary system with a load side disconnected;

FIG. 11 is a schematic diagram of the single-phase disconnection protection of the 110kV line at the power side of the invention;

FIG. 12 is a single-phase line break protection schematic diagram of a load side 110kV line of the present invention;

fig. 13 is a primary main wiring diagram of a single bus segment of a 110kV substation.

Detailed Description

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

110kV line breakage analysis:

and when the 110kV neutral point of the load side 110kV substation transformer is not grounded, the 110kV line disconnection condition is 1. And when the 110kV neutral point of the 110kV substation transformer on the load side is grounded, the 110kV line disconnection condition is 2.

1.1110 kV line broken line 1

1.1.1110 kV line broken wire

Fig. 1 is a schematic diagram of a 110kV disconnection primary system. The 110kV side of the 220kV transformer substation on the system side is an effective grounding system; 110kV neutral points of 110kV substation transformers on the load side are not grounded and are grounded through gaps.

The electric potentials of the 110kV side power supplies of the 220kV transformer substation on the system side are respectively set as E_A、E_B、E_C. When a certain part of the 110kV line is broken, such as phase A, the voltage of the 110kV bus of the 110kV transformer substation at the load side is obtained through analysis:

(1) in the formula of U_A、U_B、U_CThe voltage of A phase, B phase and C phase of 110kV bus of 110kV transformer substation at load side is U phase₀Is 110kV neutral point voltage of 110kV transformer substation on load side, 3U₀The voltage of a secondary open-delta winding of a 110kV bus voltage transformer (PT for short) of a load side 110kV substation transformer is obtained. The vector diagrams are shown in FIGS. 2 and 3.

When a 110kV line is broken, the voltage of the 110kV bus at the 220kV substation on the system side is E, and the voltage of the A phase, the voltage of the B phase and the voltage of the C phase are respectively E_A、E_B、E_C，3U₀Is 0, i.e. the three-phase voltage is maintained under normal conditions.

1.1.2110 kV line disconnection and load side disconnection grounding

Fig. 4 is a schematic diagram of a primary system with 110kV line break and load side line break grounded. The 110kV side of the 220kV transformer substation on the system side is an effective grounding system; 110kV neutral points of 110kV substation transformers on the load side are not grounded and are grounded through gaps.

The electric potentials of the 110kV side power supplies of the 220kV transformer substation on the system side are respectively set as E_A、E_B、E_C. When a certain part of the 110kV line is broken and the broken line of the load side is grounded, such as phase A, the voltage of the 110kV bus of the 110kV transformer substation on the load side is obtained through analysis:

(2) in the formula of U_A、U_B、U_CThe voltage of A phase, B phase and C phase of 110kV bus of 110kV transformer substation at load side is U phase₀Is 110kV neutral point voltage of 110kV transformer substation on load side, 3U₀The voltage of a secondary open-delta winding of a 110kV bus voltage transformer (PT for short) of a load side 110kV substation transformer is obtained. The vector diagrams are shown in fig. 5 and 6.

1.1.3110 kV line disconnection and system side disconnection point grounding

When the 110kV line is broken and the broken line of the system side is grounded, for the system side, the fault is mainly reflected in the single-phase grounding short-circuit fault of the 110kV line, so that the 110kV line protection of the 220kV transformer substation can start tripping to remove the fault (the 110kV line breaker trips to remove the fault, the 110kV line breaker is overlapped, then the single-phase grounding short-circuit fault of the 110kV line, the 110kV line protection of the 220kV transformer substation restarts tripping and removes the fault).

Analysis of 110kV neutral click-through of 110kV transformer substation in 1.1.4110 kV line disconnection

Table 1 shows the power frequency discharge voltage at different gaps. By analysing the neutral point to ground voltage U of the transformer₀It can be determined whether the gap is likely to break down, in conjunction with table 1.

TABLE 1 Power frequency discharge Voltage for different gaps

For the analytical results of 1.1.3, 3U₀Has a maximum value of 150V, and a neutral point to ground voltage U₀The secondary value is 50V, and the primary value is converted to obtain U₀The first value, the calculation result is as follows:

as the discharge gap of the neutral point of the transformer is 110mm or 120mm, the power frequency withstand voltage of the neutral point of the transformer shown in Table 1 is 52kV or 53.3kV, and the maximum steady-state voltage of the neutral point of the actual transformer is about 55kV and higher than the power frequency withstand voltage value, the discharge gap can be punctured.

1.2110 kV line broken line 2

1.2.1110 kV line broken wire

Fig. 7 is a schematic diagram of a 110kV primary disconnection system. The 110kV side of the 220kV transformer substation on the system side is an effective grounding system; 110kV neutral points of 110kV substation transformers on the load side are grounded.

(2) in the formula of U_A、U_B、U_CThe voltage of A phase, B phase and C phase of 110kV bus of 110kV transformer substation at load side is U phase₀Is 110kV neutral point voltage of 110kV transformer substation on load side, 3U₀The voltage of a secondary open-delta winding of a 110kV bus voltage transformer (PT for short) of a load side 110kV substation transformer is obtained. The vector diagrams are shown in FIGS. 8 and 9.

1.2.2110 kV line disconnection and load side disconnection grounding

Fig. 7 is a schematic diagram of a 110kV disconnection and load side disconnection grounding primary system. The 110kV side of the 220kV transformer substation on the system side is an effective grounding system; 110kV neutral points of 110kV substation transformers on the load side are grounded.

The electric potentials of the 110kV side power supplies of the 220kV transformer substation on the system side are respectively set as E_A、E_B、E_C. When a certain broken line of the 110kV line is disconnected and the broken line of the load side is grounded, such as phase A, analyzing: e_B、E_CThe synthetic potential at the low-voltage side of the 110KV transformer substation transformer at the load side is-E_aThe potential is added to a low-voltage a-phase winding of a 110kV transformer substation at the load side and is converted into a low-voltage A-phase winding of the 110kV transformer at the winding with the potential of-E_AGrounding the broken line of the 110kV line and the broken line of the load side to form an A-phase short circuit and an A-phase short circuit current I_AThe current of the low-voltage a-phase winding of the transformer is converted into I_aThe a-phase winding current is I_aForming a circulating current in a low-voltage side winding of the transformer, wherein the current of the a-phase winding is I_bPhase C winding current I_cThe current of the high-voltage B-phase winding of the transformer is converted into I_BC phase winding current is I_CDue to I_a、I_b、I_cThe currents are equal and in phase, so that I is_A、I_B、I_CThe currents are equal and in phase.

When the 110kV line is broken and the broken line of the transformer side is grounded, for the system side, the fault is mainly reflected in a short-circuit fault, and the zero-sequence current 3I of the system side₀＝(I_B+I_C)/3)＝2I_BAnd 3, therefore, the 110kV line protection of the 220kV transformer substation starts tripping to remove the fault (the 110kV line breaker trips to remove the fault, the 110kV line breaker is overlapped, then the 110kV line single-phase grounding short-circuit fault occurs, and the 110kV line protection of the 220kV transformer substation starts tripping again to remove the fault).

1.2.3110 kV line disconnection and system side disconnection point grounding

Analysis of 2.110kV line breaking result

2.1110 kV line break (or and earthing at break)

For three conditions of 1.1.1, 1.1.2 and 1.2.1, 110kV line disconnection protection can be carried out, and load transfer of 110kV line disconnection can be eliminated by matching with the backup power automatic switch, so that the influence of 110kV line disconnection on power supply load can be prevented.

Short circuit caused by 2.2110 kV line disconnection and grounding at disconnection

For three conditions of 1.1.3, 1.2.2 and 1.2.3, because short-circuit fault is caused by grounding at a broken line, tripping can be started by 110kV line protection of a 220kV transformer substation to remove the fault (110kV line breaker tripping removes the fault, 110kV line breaker is overlapped, then 110kV line single-phase grounding short-circuit fault, 220kV transformer substation 110kV line protection restarts tripping again to remove the fault); because the 110kV bus corresponding to the 110kV transformer substation at the load end loses power, the load transfer of 110kV line disconnection is eliminated by the spare power automatic switching action, and the influence of the 110kV line disconnection on the power supply load is prevented.

Fault feature analysis during disconnection of 3.110kV line

For three 110kV line disconnection conditions of 1.1.1, 1.1.2 and 1.2.1, the fault characteristics are as follows: the three-phase voltage of the 110kV bus A, B, C on the power supply side is symmetrical, the amplitude and the phase are not changed greatly, and the voltage is 3U₀Is 0, but for 2 kinds of 110kV line disconnection conditions of 1.1.1 and 1.1.2, the fault characteristics are as follows: the three-phase voltage of the 110kV bus A, B, C of the load side transformer substation is asymmetrical, and the phase voltage of the broken line is-E _A2 and about 0, 3U₀is-3E_A/2 or-E_AMeanwhile, the amplitude and the phase of the non-fault phase voltage do not change much; there is a potential for breakdown of the transformer neutral. 1.2.1 the fault signature of a broken 110kV line is similar to the case of 1.1.2, where the phase voltage of the broken line is equal to 0.

Fig. 13 shows a 110kV single-bus sectionalized primary main wiring structure of a 110kV substation:

the No. 1 power supply incoming line branch equipment and the No. 2 power supply incoming line branch equipment are respectively connected with a 110kV I section bus and a 110kV II section bus; a segmented circuit breaker 3DL is arranged between the first segment bus and the second segment bus of 110kV, and is connected with a segmented current transformer CT in series; the No. 1 power supply inlet line branch circuit spacing equipment is a circuit breaker 1DL and is connected with a current transformer CT1 in series; the No. 2 power supply inlet wire branch circuit spacing device is a circuit breaker 2DL and is connected with a current transformer CT2 in series; the 110kV I-section bus is also connected with a No. 1 transformer branch, a No. 2 transformer branch, a No. 1 110kV outgoing line branch and a 110kV I-section bus voltage transformer PT 1; the 110kV II-section bus is also connected with a No. 3 transformer branch, a No. 2 110kV outgoing line branch and a 110kV II-section bus voltage transformer PT 2. 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. The 110kV buses of the power supply end are respectively connected with 110kV PT1 and 110kVPT 2. A110 kV spare power automatic switching device is arranged on the 110kV side of a 110kV substation at a load end. The 110kV line is provided with an optical fiber channel and line optical fiber differential protection.

Aiming at the 110kV single-bus subsection primary main connection, a scheme that voltage information on two sides of a line is transmitted through a 110kV line optical fiber channel, the voltage on two sides of the line is compared to identify the line breakage of the 110kV line, a circuit breaker on the power supply side or a circuit breaker on the load side of the 110kV line is tripped, and the power supply is recovered through a spare power automatic switch of the 110kV substation on the load side is implemented at a power end 220kV substation, so that the field operation requirement is met. Based on this, the control method comprises the following control processes:

as shown in fig. 11 and 12, the method for protecting the line from being broken by comparing the voltages at two sides of the line with the backup power automatic switching device includes:

collecting PT secondary A-phase voltage U of II-section bus of 110kV transformer substation at load end_aPhase U of B phase voltage_bC phase voltage U_c Open delta voltage 3U_o

110kV transformer substation for collecting load endII-section bus PT secondary A-phase voltage U_aPhase U of B phase voltage_bC phase voltage U_c Open delta voltage 3U_o

setting value U1 is 0.55Ea, Ea is a phase voltage value, corresponding PT secondary voltage is 58V, and 0.55Ea is 31.9V; setting value U2 is 0.9Ea, and 0.9Ea is 52.2V; setting value U3 is 0.9Eab, Eab is PT secondary opening triangle rated voltage value, 100V, 0.9Eab is 90V; the setting value U4 is between 4 and 8V. the t1 time is set as: three-phase different-period time when the switch is closed is avoided: taking 0.1-0.2 seconds.

The control method for identifying the disconnection of the 110kV line by comparing the voltages at two sides of the 110kV power line is not only suitable for the non-grounding mode of the 110kV neutral point of the transformer, but also suitable for the grounding mode of the 110kV neutral point of the transformer.

The reason that the circuit breakers 1DL or 2DL and 4DL or 5DL on two sides of the incoming line of the 110kV power supply are arranged at the switching-on position is as follows: when a power supply incoming line is at a 110kV substation with a load end, the bus voltage far away from the power supply incoming line can also sense the line disconnection information, and the standby power supply circuit breaker for closing of the standby automatic switching can be interfered; in addition, when the line PT is adopted, the power incoming line may have other load end 110kV substations, and if the power incoming line breaker of the load end 110kV substation trips slowly or refuses to trip, the power incoming line breaker of the backup power automatic switching device may be interfered, and the backup power automatic switching device may not operate. The logic can be further optimized by adopting the condition that the 110kV power incoming line breaker is in the switching-on position.

After identifying the line break of the 110kV line, the tripping scheme is as follows: (1) tripping off a breaker at the power supply side of the broken line; (2) tripping off a circuit breaker on the load side of the broken line; (3) the circuit breakers on both sides of the line break are tripped together.

The 110kV neutral point operation mode of the main transformer on the I section or II section of the bus of the load end 110kV transformer substation is as follows: a) grounding; b) not grounded, grounded through the gap; the 110kV side is provided with a 110kV spare power automatic switching device. No. 1 and No. 2 power supply 110kV lines are required to be provided with fiber channels and line fiber differential protection.

The method is implemented in a single 110kV line disconnection protection device of a power supply end or a load end 110kV transformer substation or in a 110kV line protection device. The method is implemented in a 110kV line protection device, and has the advantage that no hardware equipment is required to be added.

The inventive solution can be used in the following cases: (1) the 110kV neutral point operation mode of all transformers of a load end 110kV transformer substation is as follows: a) grounding; b) not grounded, grounded through the gap; (2) a spare power automatic switching device is arranged on the 110kV side of the 110kV transformer substation; (3) no. 1 and No. 2 power supply 110kV lines are required to be provided with fiber channels and line fiber differential protection. And can satisfy the following primary main wiring: (1) a 110kV single-bus subsection primary main wiring of a 110kV transformer substation; (2) a 110kV transformer substation 110kV inner bridge primary main wiring; (3) a 110kV substation 110kV primary main wiring is enlarged; (4)110kV transformer substation 110kV line group primary main wiring; (5) a primary main wiring of the line transformer bank; (6) other primary main connections.

And if the 110kV transformer substation adopts primary main wiring of a 110kV line transformer group, recovering the power supply task by the backup power automatic switch at the low-voltage side in the load side transformer substation.

For a 110kV line with branch lines, 110kV line breakage protection of pairwise correspondence between a power end transformer substation and each load end transformer substation needs to be implemented.

The scheme of the invention can also be used in the case of the disconnection of a 220kV line powered by a single power supply.

An example of the method of the invention is given below (taking fig. 13 as an example, the transformer 110kV neutral point operates in a manner of being ungrounded, grounded via a gap):

1 operating mode 1

Under this operational mode, 2DL of No. 2 power circuit breaker, the operation of segmentation circuit breaker 3DL, 1DL of No. 1 power circuit breaker is hot standby, 1DL of No. 1 power circuit breaker branch floodgate position promptly.

No. 1.12 110kV power line single-phase line break fault

For example, if phase A is broken, phase B or phase C is broken similarly. When the phase-A single-phase disconnection fault of the No. 2 110kV power line occurs, the method is equivalent to pulling the isolating switch with load, electric arcs are generated at the disconnection moment, the electric arcs cannot be extinguished, the electric arcs further cause the phase-A single-phase grounding of the line, and the distance between the upper level No. 2kV power line and the section I or the section II of the protection range is within the distance between the upper level power line and the section I or the section II of the protection range, so that the upper level No. 2kV power line jumps away from the power side circuit breaker 5DL of the upper level No. 2kV power line through the protection; after the transformer substation at the load end loses power, the fault at the phase disconnection position of the No. 2 110kV power line A disappears, and the No. 2kV power line breaker 5DL is delayed to be successfully superposed; however, the voltage inductance of the second section of the bus of the load-side substation runs in a phase-loss mode, but the secondary voltage of the 110kV bus PT of the power supply end substation is normal, the condition that the single-phase disconnection of the No. 2 110kV power supply line is met, after the time delay t1, the 110kV line in the power supply end line protection is disconnected, and the No. 2 110kV power supply line power supply side circuit breaker 5DL is tripped. As the No. 2 110kV power line loses power, the 110kV backup power automatic switching of the 110kV transformer substation at the load end operates, the No. 2DL 110kV power circuit breaker is tripped, the No. 1DL 110kV backup power circuit breaker is started by 110kV to be switched on, and the transformer losing the power is recovered to the No. 1 backup 110kV power line to supply power.

2 operating mode 2

Under this operational mode, 1DL of power breaker, 3DL operation of section circuit breaker, 2 # power breaker 2DL are hot standby, 2 # power breaker 2DL separating brake position promptly.

No. 2.11 110kV power line single-phase line break fault

For example, if phase A is broken, phase B or phase C is broken similarly. When the A phase single-phase line break fault of the No. 1 110kV power line occurs, the method is equivalent to pulling an isolating switch with load, electric arcs are generated at the line break moment, the electric arcs cannot be extinguished, the electric arcs further cause the A phase single-phase grounding of the line, and the distance between the upper level No. 1 110kV power line and the I section or the II section of protection range is within the distance between the upper level power line and the II section, so that the upper level No. 1 kV power line jumps from a power side circuit breaker 4DL of the upper level No. 1 kV power line by the starting action of optical fiber differential protection; after the load end 110kV transformer substation loses power, the phase disconnection fault of the No. 1 110kV power line A disappears, and the superposition of the No. 1 110kV power line power side circuit breaker 4DL is successful after the time delay; however, the I section of the bus voltage of the load-side substation is subjected to open-phase operation, but the secondary voltage of the 110kV bus PT of the power supply end substation is normal, the condition that the 1 # 110kV power supply line is single-phase broken is met, after the time delay t1, the 110kV line in the power supply end line protection is broken, and the 1 # 110kV power supply line power supply side circuit breaker 4DL is jumped. As the No. 1 110kV power line loses power, the 110kV backup power automatic switching of the 110kV transformer substation at the load end acts, the No. 1 110kV power circuit breaker 1DL is tripped, and the No. 2kV backup power circuit breaker 2DL is started to be switched on, so that the transformer losing power is recovered to the backup No. 2kV power line for power supply.

3 operating mode 3

Under this operational mode, 1DL of No. 1 power circuit breaker, 2DL of No. 2 power circuit breaker operate, and the hot reserve of section circuit breaker 3DL, section circuit breaker 3DL separating brake position promptly.

No. 3.11 110kV power line single-phase line break fault

For example, if phase A is broken, phase B or phase C is broken similarly. When the A phase single-phase line break fault of the No. 1 110kV power line occurs, the method is equivalent to pulling the isolating switch with load, electric arc is generated at the line break moment, the electric arc can not be extinguished, the electric arc further causes the A phase single-phase grounding of the line, and the distance between the upper level No. 1 110kV power line and the I section or the II section of the protection range or the optical fiber differential protection starting action jumps away from the power side circuit breaker 4DL of the upper level No. 1 power line because the distance between the upper level No. 1 kV power line and the I section or the II section of the protection range is; after a first section of bus of a load end 110kV transformer substation loses power, the fault of the phase disconnection position of a No. 1 110kV power line A disappears, and the superposition of a circuit breaker 4DL on the power side of the No. 1 110kV power line is delayed to succeed; however, the I section of the bus voltage of the load-side substation is subjected to open-phase operation, but the secondary voltage of the 110kV bus PT of the power supply end substation is normal, the condition that the 1 # 110kV power supply line is single-phase broken is met, after the time delay t1, the 110kV line in the power supply end line protection is broken, and the 1 # 110kV power supply line power supply side circuit breaker 4DL is jumped. As the No. 1 110kV power line loses power, the 110kV backup power automatic switching of the 110kV transformer substation at the load end operates, the No. 1DL of the No. 1 110kV power incoming line breaker is tripped, and the 110kV backup power breaker 3DL is started to be switched on, so that the transformer losing the power is recovered to the No. 2 backup 110kV power line for power supply.

Single-phase line break fault of No. 2.22 110kV power line

For example, if phase A is broken, phase B or phase C is broken similarly. When the phase-A single-phase disconnection fault of the No. 2 110kV power line occurs, the method is equivalent to pulling the isolating switch with load, electric arcs are generated at the disconnection moment, the electric arcs cannot be extinguished, the electric arcs further cause the phase-A single-phase grounding of the line, and the distance between the phase-A single-phase grounding of the No. 2 power line at the upper level is in the protection range of the section I or the section II of the distance between the phase-A single-phase grounding and the power line at the upper level is protected by the section I or the section II of the distance between the phase-A single-phase grounding; after the II-section bus of the load-end substation loses power, the fault at the phase disconnection position of the No. 2 110kV power line A disappears, and the superposition of the No. 2 110kV power line power-side circuit breaker 5DL is successful after the time delay; however, the voltage inductance of the second section of the bus of the load-side substation runs in a phase-loss mode, but the secondary voltage of the 110kV bus PT of the power supply end substation is normal, the condition that the single-phase disconnection of the No. 2 110kV power supply line is met, after the time delay t1, the 110kV line in the power supply end line protection is disconnected, and the No. 2 110kV power supply line power supply side circuit breaker 5DL is tripped. As the No. 2 110kV power line loses power, the 110kV substation 110kV spare power automatic switching at the load end acts, the No. 2 110kV power circuit breaker 2DL is tripped, and the 110kV spare power circuit breaker 3DL is started to be switched on, so that the transformer losing the power is restored to the spare No. 1 110kV power line for power supply.

In addition to the above embodiments, the present invention may have other embodiments, and any technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of the claims of the present invention.

Claims

1. A circuit disconnection protection method for comparing voltages on two sides of a circuit and matching with a spare power automatic switch is characterized by comprising the following steps:

collection load end 110kV transformer substation I section bus PT secondary A phase voltage U_aPhase U of B phase voltage_bC phase voltage U_cOpen delta voltage 3U_o

2. The line disconnection protection method for comparing the voltage on two sides of the line and the spare power automatic switching device, as claimed in claim 1, wherein the setting value U1 is 0.55Ea, Ea is the phase voltage value, the corresponding PT secondary voltage is 58V, and 0.55Ea is 31.9V; setting value U2 is 0.9Ea, and 0.9Ea is 52.2V; setting value U3 is 0.9Eab, Eab is PT secondary opening triangle rated voltage value, 100V, 0.9Eab is 90V; the setting value U4 is between 4 and 8V.

3. The method for protecting the line disconnection by comparing the voltage on the two sides of the line with the spare power automatic switching device according to claim 1, wherein the time t1 is defined as: three-phase different-period time when the switch is closed is avoided: taking 0.1-0.2 seconds.

4. The method for protecting against disconnection of a line by comparing a voltage across the line with a backup power automatic switching device according to claim 1, wherein the method is applied to a 110kV neutral point ungrounded mode of the transformer and a 110kV neutral point grounded mode of the transformer.