CN110829390B

CN110829390B - 110kV wire break protection method for measuring load side voltage and matching with spare power automatic switching

Info

Publication number: CN110829390B
Application number: CN201911186589.8A
Authority: CN
Inventors: 陈永明; 杨茹; 李静; 胡航; 宋丽; 侯超; 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: 2020-11-10
Anticipated expiration: 2039-11-28
Also published as: CN110829390A

Abstract

The invention discloses a 110kV disconnection protection method for measuring the voltage of a load side and matching with a spare power automatic switch. The fault characteristics of the PT secondary voltage of the 110kV bus of the load-side substation when the 110kV line is disconnected in a single-phase mode are fully utilized, the 110kV line single-phase disconnection tripping 110kV line power supply side circuit breaker or the load side circuit breaker is identified, and the method is simple and easy to implement. The invention adopts the load-end substation to judge the single-phase line break of the 110kV power line, and starts the remote tripping function of the optical fiber differential protection of the line through the 110kV power line to remotely trip the circuit breaker at the power side of the 110kV line, and then starts the trip incoming line circuit breaker and closes the standby power circuit breaker by the 110kV backup automatic switching action of the load-end substation, so that the transformer losing the power supply is recovered to the standby power supply to supply power, thereby effectively preventing the influence of the phase-lacking power supply of the transformer on the power grid and the load power supply and the 110kV transformer 110kV neutral point burnout, and being beneficial to the safe and stable operation of the.

Description

110kV wire break protection method for measuring load side voltage and matching with spare power automatic switching

Technical Field

The invention relates to a 110kV disconnection protection method for measuring the matching of load side voltage and spare power automatic switching, and belongs to the technical field of power equipment.

Background

At present, the phenomenon of disconnection of 110kV lines occurs in each regional power grid. 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, and the invention provides a single-phase disconnection relay protection technical scheme which is used for identifying 110kV line disconnection based on circuit breaker position judgment at a load end substation, starting a circuit breaker at a far jump 110kV line power supply side through 110kV line optical fiber current differential protection, or starting a circuit breaker at a jump 110kV line disconnection load side, and recovering power supply through a load end 110kV substation backup automatic switch.

Disclosure of Invention

The invention aims to provide a 110kV disconnection protection method for measuring the voltage on the load side and matching with a spare power automatic switch. The single-phase disconnection relay protection method can be applied to a power transmission and distribution network, and is used for starting a circuit breaker at a power supply side of a long-jump 110kV line or a circuit breaker at a load side of a jump 110kV disconnection line through 110kV line optical fiber current differential protection, and recovering power supply through a backup automatic switch of a load end 110kV transformer substation.

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

a 110kV disconnection protection method for measuring the voltage at the load side and matching with a spare power automatic switch,

method for identifying each phase disconnection of 110kV line

Method for identifying each phase disconnection of No. 1.11 power supply incoming line circuit

Collecting a PT secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a first section of a bus of a load end 110kV transformer substation,

condition 1:

1) a-phase broken line identification method

(1) The voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U1;

(2) the voltage value of the PT secondary B phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;

(3) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;

(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is between the upper limit and the lower limit of a setting voltage value U3;

when the conditions are all met, a phase disconnection signal of a No. 1 110kV power supply incoming line circuit A is sent out after a delay of t 1;

2) b-phase broken line identification method

(1) The voltage value of the PT secondary B phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U1;

(2) the voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;

(3) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;

when the conditions are all met, a No. 1 110kV power incoming line B phase disconnection signal is sent out after the time delay of t 1;

3) c-phase broken line identification method

(1) The voltage value of the PT secondary C phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U1;

(2) the voltage value of the PT secondary A phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;

(3) the voltage value of the PT secondary B phase of the I section bus is between the upper limit and the lower limit of a setting voltage value U2;

when the above conditions are all met, a No. 1 110kV power supply incoming line C phase disconnection signal is sent out after the time delay of t1,

condition 2:

1) a-phase broken line identification method

(1) The voltage value of the PT secondary A phase of the I section bus is smaller than a setting voltage value U5;

(4) the secondary voltage value of the PT secondary opening triangle of the I section of the bus is between the upper limit and the lower limit of a setting voltage value U4;

2) b-phase broken line identification method

(1) The voltage value of the PT secondary B phase of the I section bus is smaller than a setting voltage value U5;

3) c-phase broken line identification method

(1) The voltage value of the PT secondary C phase of the I section bus is smaller than a setting voltage value U5;

when the conditions are all met, a No. 1 110kV power supply incoming line C phase disconnection signal is sent out after time delay t 1;

method for identifying each phase disconnection of No. 1.22 power supply incoming line circuit

Collecting a secondary A-phase voltage Ua, a B-phase voltage Ub, a C-phase voltage Uc and an open delta voltage 3Uo of a PT (potential transformer) of a II-section bus of a 110kV transformer substation at a load end;

condition 1:

1) a-phase broken line identification method

(1) The voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U1;

(2) the voltage value of the secondary B phase of the PT bus of the section II is between the upper limit and the lower limit of a setting voltage value U2;

(3) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;

(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is between the upper limit and the lower limit of a setting voltage value U3;

when the conditions are all met, a No. 2 110kV power incoming line A phase disconnection signal is sent out after the time delay of t 1;

2) b-phase broken line identification method

(1) The voltage value of the secondary B phase of the PT bus of the section II is between the upper limit and the lower limit of a setting voltage value U1;

(2) the secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U2;

(3) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;

when the conditions are all met, a No. 2 110kV power incoming line B phase disconnection signal is sent out after the time delay of t 1;

3) c-phase broken line identification method

(1) The secondary C-phase voltage value of the II-section bus PT is between the upper limit and the lower limit of a setting voltage value U1;

(2) the voltage value of the secondary A phase of the PT of the II section of bus is between the upper limit and the lower limit of a setting voltage value U2;

when the conditions are all met, a No. 2 110kV power incoming line C phase disconnection signal is sent out after a delay of t 1;

condition 2:

1) a-phase broken line identification method

(1) The voltage value of a secondary A phase of a PT section II bus is smaller than a setting voltage value U5;

(4) the secondary voltage value of the PT secondary opening triangle of the II section of bus is between the upper limit and the lower limit of a setting voltage value U4;

2) b-phase broken line identification method

(1) The voltage value of a secondary B phase of a PT section II bus is smaller than a setting voltage value U5;

when the conditions are all met, a No. 2 power supply incoming line B phase disconnection signal of the 110kV line is sent out after time delay t 1;

3) c-phase broken line identification method

(1) The secondary C-phase voltage value of the II-section bus PT is smaller than a setting voltage value U5;

1.3 in the above 1.1 and 1.2, condition 1 is a relay protection identification method for a certain phase disconnection of a 110kV line; and the condition 2 is a relay protection identification method aiming at the situation that a certain phase of a 110kV line is disconnected and a load end at the disconnection position is simultaneously grounded in a single phase.

Second, judging the conditions of starting the 110kV line disconnection and tripping the power supply side circuit breaker or the load side circuit breaker of the 110kV line disconnection line and recovering power supply by the 110kV backup power automatic switch

2.1 conditions for judging 1 # 110kV line disconnection tripping 1 # 110kV line disconnection line power supply side circuit breaker 4DL or load side circuit breaker 1DL and switching standby power supply circuit breaker 2DL or 3DL by load side 110kV backup power automatic switching start

Collecting secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc and open triangular voltage 3Uo of a first-section bus PT of a load end 110kV transformer substation, and current of a CT at a 110kV neutral point gap of a No. 1 transformer and a No. 2 transformer;

condition 1:

the condition 1 or the condition 2 of the method for identifying the disconnection of each phase of the No. 1 110kV power line is met, after t2 or t4 is delayed respectively, and the No. 1 110kV incoming line breaker 1DL of the load end 110kV transformer substation is at the switching-on position, the No. 1 110kV power line power supply side breaker 4DL is tripped far by starting the remote tripping function of the No. 1 110kV power line optical fiber differential protection; as 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 off, and the spare power breaker 2DL or 3DL is closed, so that the transformer losing the power is recovered to the spare No. 2kV power line for power supply; or starting a trip circuit incoming line breaker 1DL, and starting a spare No. 2 110kV power supply breaker 2DL or 3DL to switch on by 110kV spare power automatic switching, so that the transformer losing the power supply is recovered to a spare No. 2 110kV power supply line for supplying power;

condition 2:

(1) the method comprises the following steps of satisfying condition 1 or condition 2 of the phase disconnection identification method of the No. 1 110kV power line, and opening T time, namely, opening a primary pulse with high level time of T;

(2) the zero sequence current 3Io of the neutral point of the No. 1 or No. 2 main transformer is greater than a setting value I1;

when the conditions are all met and t3 is delayed, and the No. 1 110kV incoming line breaker 1DL of the 110kV transformer substation at the load end is at the switching-on position, the No. 1 110kV power line power supply side breaker 4DL is remotely tripped by starting the remote tripping function of the No. 1 110kV power line optical fiber differential protection; as 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 off, and the spare power breaker 2DL or 3DL is closed, so that the transformer losing the power is recovered to the spare No. 2kV power line for power supply; or starting a trip circuit incoming line breaker 1DL, and starting a spare No. 2 110kV power supply breaker 2DL or 3DL to switch on by 110kV spare power automatic switching, so that the transformer losing the power supply is recovered to a spare No. 2 110kV power supply line for supplying power;

2.2 conditions for judging 2 # 110kV line disconnection jumping 2 # 110kV line disconnection power supply side circuit breaker 5DL or load side circuit breaker 2DL and switching 1DL or 3DL of standby power supply circuit breaker by load side 110kV backup power automatic switching

Collecting secondary A-phase voltage Ua, B-phase voltage Ub, C-phase voltage Uc, open triangular voltage 3Uo and current of CT at 110kV neutral point gap of No. 3 transformer of II-section bus PT of load end 110kV transformer substation;

condition 1:

the condition 1 or the condition 2 of the method for identifying the disconnection of each phase of the No. 2 110kV power line is met, after the time is delayed by t2 or t4, and after the No. 2kV incoming line breaker 2DL of the load end 110kV transformer substation is at the switching-on position, the No. 2kV power line power supply side breaker 5DL is remotely tripped by starting the remote tripping function of the No. 2 110kV power line optical fiber differential protection; 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 off, the spare power supply breaker 1DL or 3DL is closed, and the transformer losing the power is recovered to the spare No. 1 110kV power line for power supply; or starting a trip circuit incoming line breaker 2DL, and starting a spare No. 1 110kV power supply breaker 1DL or 3DL to switch on by 110kV spare power automatic switching, so that the transformer losing the power supply is recovered to a spare No. 1 110kV power supply line for supplying power;

condition 2:

(1) the condition 1 or the condition 2 of the method for identifying the disconnection of each phase of the No. 2 110kV power line is met, and the T time is opened;

(2) the zero sequence current 3Io of the neutral point of the No. 3 main transformer is greater than a setting value I1;

when the conditions are all met and t3 is delayed, and the No. 2 110kV incoming line breaker 2DL of the 110kV transformer substation at the load end is at the switching-on position, the No. 2 110kV power line power supply side breaker 5DL is remotely tripped by starting the remote tripping function of the No. 2 110kV power line optical fiber differential protection; 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 off, the spare power supply breaker 1DL or 3DL is closed, and the transformer losing the power is recovered to the spare No. 1 110kV power line for power supply; or starting the tripping line incoming circuit breaker 2DL, and starting the standby No. 1 110kV power supply breaker 1DL or 3DL to switch on by the 110kV backup automatic switch, so that the transformer losing the power supply is recovered to the standby No. 1 110kV power supply line for supplying power.

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

the 110kV disconnection protection method for measuring the voltage on the load side and matching with the backup power automatic switch comprises the following steps:

the upper limit and the lower limit of the setting voltage value U1 are 26.1-31.9V, the upper limit and the lower limit of the setting voltage value U2 are 52.2-63.8V, the upper limit and the lower limit of the setting voltage value U3 are 135-165V, the upper limit and the lower limit of the setting voltage value U4 are 90-110V, and the setting voltage value U5 is 10V.

The 110kV disconnection protection method for measuring the voltage on the load side and matching with the backup power automatic switch comprises the following steps: the t1 time is set to be 0.1-0.2 seconds; setting the t2 time to be 0.15-0.5 seconds; setting the t3 time to be 0.15-0.5 seconds; the t4 time is set to be 2.5-4 seconds; the opening T time is set to be 5-7 seconds; the current setting value I1 is 40-100A.

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

1. the method fully utilizes the fault characteristics of the PT secondary voltage of the 110kV bus of the load-side substation when the 110kV line is disconnected in a single-phase manner, and identifies the 110kV line single-phase disconnection tripping 110kV line power supply side circuit breaker or the load side circuit breaker to be simple and easy.

2. The invention adopts the load-end substation to judge the single-phase line break of the 110kV power line, and starts the remote trip function of the optical fiber differential protection of the line through the 110kV power line to trip the breaker (or trip the breaker at the load side) at the power side of the 110kV line far, and then starts the trip incoming line breaker and closes the breaker of the standby power supply by the 110kV spare power automatic switching action of the load-end substation, so that the transformer losing the power supply is recovered to the relay protection scheme of the power supply on the standby power supply, thereby effectively preventing the influence of the phase-lacking power supply of the transformer on the power grid and the power supply of the load, simultaneously preventing the 110kV transformer 110kV neutral point from being burnt out, and being.

3. According to the invention, the incoming line breaker of No. 110kV1 (or No. 2) of the transformer substation with the load end added is adopted to judge at the switching-on position, so that the misoperation of the disconnection protection can be prevented.

4. The invention is implemented by adopting an individual 110kV line disconnection protection device of a 110kV transformer substation at a load end where a load end transformer is located or implemented in a 110kV line protection device and a transformer protection device; when the circuit breaker is implemented in a single 110kV circuit breaker or a 110kV circuit breaker, new hardware interfaces such as 3Uo and 3Io are required to be added; the protection device is implemented in the No. 1, No. 2 and No. 3 transformer protection devices, and does not need to add hardware equipment.

5. The condition 1 of starting the control method for 110kV line disconnection protection by adopting the condition 2 of the control method for identifying the disconnection of each phase of the 110kV power line is not only suitable for a 110kV neutral point ungrounded mode of the transformer, but also suitable for a 110kV neutral point grounded mode of the transformer.

Drawings

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

FIG. 2 is a first vector diagram of a 110kV line disconnection;

FIG. 3 is a first schematic diagram of a 110kV disconnection and load side disconnection grounding primary system;

FIG. 4 is a second vector diagram of 110kV line disconnection;

FIG. 5 is a schematic diagram II of a 110kV disconnection primary system;

FIG. 6 is a third vector diagram of 110kV line disconnection;

FIG. 7 is a schematic diagram II of a 110kV line break and load side line break grounding primary system;

FIG. 8 is a schematic diagram of the single-phase disconnection protection of the 110kV line of the present invention;

fig. 9 is a primary main wiring diagram of a single bus segment of a 110kV substation.

The symbols in the figures are as follows:

-representing a logical and relationship, i.e. the output is valid when all input conditions are fulfilled;

-representing a logical or relationship, i.e. the output is valid when any of the input conditions is fulfilled;

-represents the open T time relationship, i.e. the open T time when any of the input conditions is fulfilled.

Detailed Description

110kV line breakage analysis:

1.110 kV line break 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 vector diagram of the voltage of the secondary open-delta winding of the 110kV bus voltage transformer (PT for short) of the 110kV substation transformer at the load side is shown in figure 2.

1.1.2110 kV line disconnection and load side disconnection grounding

Fig. 3 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 vector diagram of the voltage of the secondary open-delta winding of the 110kV bus voltage transformer (PT for short) of the 110kV substation transformer at the load side is shown in figure 4.

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 of the transformerVoltage to earth U₀It 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. 5 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 vector diagram of the voltage of the secondary open-delta winding of the 110kV bus voltage transformer (hereinafter referred to as PT) of the 110kV substation transformer at the load side is shown in FIG. 6.

1.2.2110 kV line disconnection and load side disconnection grounding

Fig. 4 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 a load side and is converted into a low-voltage A-phase winding of the 110kV transformer at the winding, and the potential is-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_cFor converting the current of a high-voltage B-phase winding of a 110kV transformer 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 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_AWhile the amplitude and phase of the non-fault phase voltage do not change much, and in addition, the neutral point voltage U of the transformer₀Are all-E_A/2. There is a potential for breakdown of the transformer neutral. 1.2.1 the 110kV line disconnection faultFeatures are similar to the case of 1.1.2, except U₀＝0。

In view of the above situation, the present invention provides a 110kV disconnection protection method for measuring the voltage at the load side and matching with the backup power automatic switch.

The transmission and distribution network applied by the invention is a system network such as a 110kV single-bus subsection primary main connection (including a 110kV single-bus primary main connection), a 110kV inner bridge connection, a 110kV expansion inner bridge connection, a 110kV transformer bank connection of a line of a transformer substation and the like of a 110kV substation. Taking the primary main wiring of the 110kV single bus subsection of the 110kV substation as an example, the protection method of other primary main wirings is similar. The 110kV single-bus subsection primary main wiring structure of the 110kV substation is shown in fig. 9:

the No. 1 power supply incoming line branch equipment and the No. 2 power supply incoming line branch equipment are respectively connected with a 110kV I section bus and a 110kV II section bus; a segmented circuit breaker 3DL is arranged between the first segment bus and the second segment bus of 110kV, and is connected with a segmented current transformer CT in series; the No. 1 power supply inlet line branch circuit spacing equipment is a circuit breaker 1DL and is connected with a current transformer CT1 in series; the No. 2 power supply inlet wire branch circuit spacing device is a circuit breaker 2DL and is connected with a current transformer CT2 in series; the 110kV I-section bus is also connected with a No. 1 transformer branch, a No. 2 transformer branch, a No. 1 110kV outgoing line branch and a 110kV I-section bus voltage transformer PT 1; the 110kV II-section bus is also connected with a No. 3 transformer branch, a No. 2 110kV outgoing line branch and a 110kV II-section bus voltage transformer PT 2. No. 1 power inlet wire circuit power supply side is equipped with circuit breaker 4DL, and No. 2 power inlet wire circuit power supply side is equipped with circuit breaker 5DL, and 110kV spare power automatic switching device is installed to load end 110kV transformer substation 110kV side. 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, 110kV line disconnection is identified in a load end 110kV transformer substation, a remote trip 110kV line power supply side circuit breaker or a trip 110kV line disconnection load side circuit breaker is started through 110kV line optical fiber current differential protection, and a single-phase disconnection relay protection scheme for restoring power supply through a load end 110kV transformer substation backup power automatic switch is adopted to meet the field operation requirement. The specific method is shown in fig. 8:

method for identifying each phase disconnection of 110kV line

condition 1:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

condition 2:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

condition 1:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

condition 2:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

condition 1:

condition 2:

condition 1:

condition 2:

2.3 in 2.1 and 2.2 above,

(1) the reason why the condition 2 is adopted is that: once the 110kV neutral point gap of the transformer running on the bus is broken down, the condition 1 does not meet the starting condition and returns when the 110kV neutral point of the transformer is grounded, and the starting condition can be further optimized by adopting the condition 2;

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

(3) The condition 1 of starting the control method for 110kV line disconnection protection by adopting the condition 2 of the control method for identifying the disconnection of each phase of the 110kV power line is not only suitable for a 110kV neutral point ungrounded mode of the transformer, but also suitable for a 110kV neutral point grounded mode of the transformer.

3. The 110kV neutral point operation mode of the main transformer on the I section or II section of the bus of the load end 110kV 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. When a circuit breaker on the power supply side of a broken line is subjected to long jump, the No. 1 and No. 2 power supply 110kV lines are required to be provided with an optical fiber channel and line optical fiber differential protection.

4. The single-phase line breaking relay protection method for judging the circuit breaker at the 110kV line power supply side based on the position of the circuit breaker is implemented in a single 110kV line breaking protection device of a load end 110kV transformer substation or in a 110kV line protection device and a transformer protection device; when the method is implemented in a 110kV line protection device, new hardware interfaces such as 3UO and 3Io are required to be added; the protection is implemented in the protection of No. 1, No. 2 and No. 3 transformers, and hardware equipment does not need to be added.

5. The load end 110kV transformer substation 110kV bus line breaking phase PT secondary setting value is as follows:

the overall setting principle is as follows: according to plus or minus 10 percent of corresponding theoretical value

(1) Condition 1: the setting value of the line break phase PT secondary voltage is as follows: 1/2, the phase rated voltage value is +/-10% (29V +/-10%), namely between 26 and 32V; condition 2: the setting value of the line break phase PT secondary voltage is as follows: less than or equal to 10V.

(2) The setting value of the non-broken line phase PT secondary voltage is as follows: the phase rated voltage value is +/-10% (58V +/-10%), namely between 53 and 64V;

(3) condition 1: the voltage setting value of the bus PT secondary opening triangle is as follows: 150V +/-10%, namely 135-165V; condition 2: the voltage setting value of the bus PT secondary opening triangle is as follows: 100V +/-10%, namely 90-110V.

6. In the single-phase disconnection relay protection method for judging the circuit breaker tripping at the 110kV line power supply side based on the circuit breaker position, setting values of time and current are as follows:

(1) the t1 time is set to be 0.1-0.2 seconds;

(2) setting the t2 time to be 0.15-0.5 seconds;

(3) setting the t3 time to be 0.15-0.5 seconds;

(4) time t 4: the trip time of the single-phase grounding protection action of the line needs to be avoided and is set to be 2.5-4 seconds;

(5) the condition 1 or the condition 2 of the control method for identifying each phase disconnection of the 110kV line meets the condition, and the opening T time is set to be 5-7 seconds;

(6) the setting value of the zero sequence current 3Io of the 110kV neutral point of the main transformer is set to be 40-100A.

7. When the 110kV transformer substation adopts primary main wiring of a 110kV line transformer group, the spare power automatic switching device on the middle and low voltage sides of the transformer substation on the load side completes the task of power restoration.

8. The inventive solution can be used in the following cases: (1) the 110kV neutral point operation mode of all transformers of a load end 110kV transformer substation is as follows: 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; (4) other primary main connections.

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

An embodiment of the method of the present invention is given below, taking fig. 9 as an example, taking condition 1 (far trip line power source side circuit breaker) of the control method for identifying each phase of the broken line of the 110kV line as an example, and condition 2 is similar; the 110kV neutral point operation mode of the transformer is as follows: ungrounded, grounded through a gap:

1. mode of operation 1

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

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, so that the distance between the upper-level No. 2kV power line and the section I or the section II of the protection range or the optical fiber differential protection starting action jumps away from the circuit breaker 5DL at the power side of the upper-level No.; after the transformer substation at the load end loses power, the fault at the phase disconnection position of the 110kV power line A disappears, and the circuit breaker 5DL of the 110kV power line is successfully superposed; however, the voltage inductance of the first section or the second section of the bus of the load-end substation is in open-phase operation, the PT secondary voltage of the second section of the bus meets the condition that the single-phase disconnection condition 1 of the No. 2 110kV power line is met, the A-phase single-phase disconnection fault of the 110kV power line is sent out after the delay of t1, after the delay of t2, the No. 2 No. 110kV incoming line breaker 2DL of the load-end 110kV substation is in the switching-on position, and the No. 2 No. 110kV power line power-side breaker 5DL is tripped through the remote tripping function of starting the optical fiber differential protection of the No. 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. 2 110kV power circuit breaker 2DL is tripped, the 110kV starting backup power circuit breaker 1DL is switched on, and the transformer losing the power is recovered to the backup No. 2kV power line for power supply.

The T time is opened because the above condition 1 is satisfied; if the time t2 does not reach, the 110kV neutral point of the No. 3 main transformer is broken down, the generated zero sequence current exceeds the setting value, after the time delay of 3 times, and the No. 2kV incoming line circuit breaker 2DL of the load end 110kV transformer substation is at the switching-on position, the No. 2 110kV power line power supply side circuit breaker 5DL is tripped by starting the remote tripping function of the No. 2 110kV power line optical fiber differential protection. 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. 2 110kV power circuit breaker 2DL is tripped, the 110kV starting backup power circuit breaker 1DL is switched on, and the transformer losing the power is recovered to the backup No. 2kV power line for power supply.

2. Mode of operation 2

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

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 a load end transformer substation loses power, the fault of the phase-A broken line of the 110kV power line disappears, the circuit breaker 4DL on the power side of the 1 # 110kV power line is successfully superposed, but the voltage of the first section of bus of the load end 110kV transformer substation is subjected to open-phase operation, the PT secondary voltage of the first section of bus meets the condition 1 for identifying the 1 # 110kV line single-phase broken line, the phase-A single-phase broken line fault of the 1 # 110kV power line is sent out through time delay t1, after time delay of t2, the circuit breaker 1DL on the power side of the 1 # 110kV power line is tripped at the closing position through the remote tripping function of starting the optical fiber differential protection of the 1 # 110kV line. 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.

Since condition 1 is satisfied, open T time; if the time t2 does not reach, the 110kV neutral point of the No. 1 or No. 2 main transformer breaks down, the generated zero sequence current exceeds the setting value, after the time delay of t3, the No. 1 110kV incoming line circuit breaker 1DL of the 110kV transformer substation at the load end is at the switching-on position, and the No. 1 110kV power supply line power supply side circuit breaker 4DL is tripped through starting the remote tripping function of the No. 1 110kV line optical fiber differential protection. 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. Mode for operation 3

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

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

For example, if phase A is broken, phase B or phase C is broken similarly. When the A phase single-phase disconnection fault of the No. 1 110kV power line occurs, the method is equivalent to pulling the isolating switch with load, electric arcs are generated at the disconnection moment, the electric arcs cannot be extinguished, the electric arcs further cause the A phase single-phase grounding of the line, and the distance between the No. 1 power line and the I section or the II section of the protection range of the superior power line is within the distance between the No. 1 power line and the superior power line, or the optical fiber differential protection starting action jumps away from the power-side circuit breaker 4DL of the superior No. 2 power line; after the I section of bus of the load-end substation loses power, the fault of the phase-A disconnection position of the 110kV power line disappears, the circuit breaker 4DL on the power side of the 1 # 110kV power line is successfully superposed, but the voltage induction of the I section of bus of the load-end substation is in open-phase operation, the PT secondary voltage of the I section of bus meets the condition 1 of the 1 # 110kV power line single-phase disconnection, the phase-A single-phase disconnection fault of the 1 # 110kV power line is sent out by the delay t1, and after the delay of t2, the circuit breaker on the power side of the 1 # 110kV power line is switched on by starting the remote tripping function of the optical fiber differential protection of the 1 # 110kV power line, and the circuit breaker on the power side of the 1 # 110kV power line is switched on. As the No. 1 110kV power line loses power, the 110kV backup power automatic switching action of the 110kV transformer substation at the load end trips the No. 1 110kV power circuit breaker 1DL, and the No. 110kV2 backup power circuit breaker 3DL is started to be switched on, so that the transformer losing power is restored to the backup No. 2kV power line for power supply.

Since condition 1 is satisfied, open T time; if the time t2 does not reach, the 110kV neutral point of the No. 1 or No. 2 main transformer breaks down, the generated zero sequence current exceeds the setting value, after the time t3 is delayed, the No. 1 110kV incoming line circuit breaker of the load end 110kV transformer substation is at the switching-on position, and the No. 1 110kV power line power supply side circuit breaker 4DL is tripped through starting the remote tripping function of the No. 1 110kV line optical fiber differential protection. As the No. 1 110kV power line loses power, the 110kV backup power automatic switching action of the 110kV transformer substation at the load end trips the No. 1 110kV power circuit breaker 1DL, and the No. 110kV2 backup power circuit breaker 3DL is started to be switched on, so that the transformer losing power is restored to the backup No. 2kV 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 second section of bus of the load-end substation loses power, the fault of the phase-A disconnection position of the No. 2 110kV power line disappears, the circuit breaker 5DL on the power side of the No. 2kV power line is successfully superposed, but the voltage induction of the second section of bus of the load-end substation is in open-phase operation, the PT secondary voltage of the second section of bus meets the condition 1 that the phase-A disconnection condition of the No. 2 110kV power line is met, the phase-A disconnection fault of the No. 2kV power line is sent out through time delay t1, after the time delay of t2, the phase-A disconnection fault of the No. 2kV incoming line circuit breaker 2DL of the load-end 110kV substation is in the switching-on position, and the phase-A disconnection fault on the power side of the No. 2kV power line 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 acts, the No. 2DL 110kV power circuit breaker is tripped, and the No. 2DL 110kV backup power circuit breaker is started to be switched on, so that the transformer losing power is restored to the backup No. 1 110kV power line to supply power.

Since condition 1 is satisfied, open T time; if the time t2 does not reach, the 110kV neutral point of the No. 3 main transformer is broken down, the generated zero sequence current exceeds the setting value, after the time t3 is delayed, the No. 2kV incoming line circuit breaker 2DL of the 110kV transformer substation at the load end is at the switching-on position, and the No. 2kV power line power supply side circuit breaker 5DL is tripped through starting the remote tripping function of the No. 2kV 110kV line optical fiber differential protection. As the No. 2 110kV power line loses power, the 110kV backup power automatic switching of the 110kV transformer substation at the load end acts, the No. 2DL 110kV power circuit breaker is tripped, and the No. 2DL 110kV backup power circuit breaker is started to be switched on, so that the transformer losing power is restored to the backup No. 1 110kV power line to supply power.

Claims

1. A110 kV disconnection protection method for measuring the voltage at the load side and matching with a spare power automatic switch is characterized in that,

method for identifying each phase disconnection of 110kV line

condition 1:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

condition 2:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

condition 1:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

(3) the voltage value of the secondary B phase of the PT bus of the section II is between the upper limit and the lower limit of a setting voltage value U2;

condition 2:

1) a-phase broken line identification method

2) b-phase broken line identification method

3) c-phase broken line identification method

1.3 in the above 1.1 and 1.2, condition 1 is a relay protection identification method for a certain phase disconnection of a 110kV line; the condition 2 is a relay protection identification method aiming at the situation that a certain phase of a 110kV line is disconnected and a load end at the disconnection position is simultaneously grounded in a single phase;

2.1 conditions for judging 1 # 110kV line disconnection tripping 1 # 110kV line disconnection line power supply side circuit breaker 4DL or load side circuit breaker 1DL and starting load side circuit breaker 2DL or sectional circuit breaker 3DL by load side 110kV backup power automatic switching

condition 1:

when the condition 1 or the condition 2 of the method for identifying the disconnection of each phase of the No. 1 110kV power line is met, after the time is delayed by t2 or t4, the load side circuit breaker 1DL is in a switching-on position, and the No. 1 110kV power line power side circuit breaker 4DL is remotely tripped by starting a remote tripping function of the No. 1 110kV power line optical fiber differential protection; because the No. 1 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching device acts to start the tripping load side circuit breaker 1DL, close the load side circuit breaker 2DL or the sectional circuit breaker 3DL, so that the transformer losing power is restored to the standby No. 2kV power line for supplying power; or starting the load tripping side circuit breaker 1DL, and starting the load side circuit breaker 2DL or the sectional circuit breaker 3DL to switch on by the 110kV backup automatic switch, so that the transformer losing the power supply is recovered to the standby No. 2 110kV power line for power supply;

condition 2:

when the conditions are all met, after time delay t3, and the load side circuit breaker 1DL is at the switching-on position, the 1 # 110kV power line power supply side circuit breaker 4DL is remotely tripped by starting the remote tripping function of the 1 # 110kV power line optical fiber differential protection; because the No. 1 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching device acts to start the tripping load side circuit breaker 1DL, close the load side circuit breaker 2DL or the sectional circuit breaker 3DL, so that the transformer losing power is restored to the standby No. 2kV power line for supplying power; or starting the load tripping side circuit breaker 1DL, and starting the load side circuit breaker 2DL or the sectional circuit breaker 3DL to switch on by the 110kV backup automatic switch, so that the transformer losing the power supply is recovered to the standby No. 2 110kV power line for power supply;

2.2 conditions for judging No. 2 110kV line disconnection jumping No. 2kV line disconnection power supply side circuit breaker 5DL or load side circuit breaker 2DL and starting combined load side circuit breaker 1DL or sectional circuit breaker 3DL by load side 110kV backup power automatic switching

condition 1:

when the condition 1 or the condition 2 of the method for identifying the disconnection of each phase of the No. 2 110kV power line is met, after the time is delayed for t2 or t4, and the load side circuit breaker 2DL is at the switching-on position, the No. 2 110kV power line power side circuit breaker 5DL is remotely tripped by starting the remote tripping function of the No. 2 110kV power line optical fiber differential protection; because the No. 2 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching device acts to start the tripping load side circuit breaker 2DL, close the load side circuit breaker 1DL or the sectional circuit breaker 3DL, so that the transformer losing power is restored to the standby No. 1 110kV power line for power supply; or starting the load tripping side circuit breaker 2DL, and starting the load side circuit breaker 1DL or the sectional circuit breaker 3DL to switch on by the 110kV backup automatic switch, so that the transformer losing the power supply is recovered to the standby No. 1 110kV power line for power supply;

condition 2:

when the conditions are all met, after time delay t3, and the load side circuit breaker 2DL is at the switching-on position, the No. 2 110kV power line power supply side circuit breaker 5DL is remotely tripped by starting the remote tripping function of the No. 2 110kV power line optical fiber differential protection; because the No. 2 110kV power line loses power, the load end 110kV transformer substation 110kV spare power automatic switching device acts to start the tripping load side circuit breaker 2DL, close the load side circuit breaker 1DL or the sectional circuit breaker 3DL, so that the transformer losing power is restored to the standby No. 1 110kV power line for power supply; or starting the load tripping side circuit breaker 2DL, and starting the load side circuit breaker 1DL or the sectional circuit breaker 3DL by the 110kV backup automatic switch to switch on, so that the transformer losing the power supply is recovered to the standby No. 1 110kV power line for supplying power.

2. The 110kV disconnection protection method for measuring the cooperation of the load side voltage and the spare power automatic switching device according to claim 1, wherein the upper limit and the lower limit of a setting voltage value U1 are 26.1-31.9V, the upper limit and the lower limit of a setting voltage value U2 are 52.2-63.8V, the upper limit and the lower limit of a setting voltage value U3 are 135-165V, the upper limit and the lower limit of a setting voltage value U4 are 90-110V, and the setting voltage value U5 is 10V.

3. The method for protecting the disconnection of a 110kV line by measuring the voltage on the load side and matching with the spare power automatic switching device according to claim 1, wherein the t1 time is set to be 0.1-0.2 seconds; setting the t2 time to be 0.15-0.5 seconds; setting the t3 time to be 0.15-0.5 seconds; the t4 time is set to be 2.5-4 seconds; the opening T time is set to be 5-7 seconds; the current setting value I1 is 40-100A.