CN110676822A

CN110676822A - Line disconnection relay protection method for comparing voltage difference between two sides of line and application

Info

Publication number: CN110676822A
Application number: CN201911186598.7A
Authority: CN
Inventors: 李静; 陈永明; 杨茹; 胡航; 曹斌; 汤大海; 魏刚; 王律; 徐溯; 张�浩
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: 2020-01-10
Anticipated expiration: 2039-11-28
Also published as: CN110676822B

Abstract

The invention discloses a line disconnection relay protection method and application for comparing voltage difference between two sides of a line, which are characterized in that the single-phase disconnection of a 110kV line is identified by utilizing the fault characteristics of PT secondary voltages of 110kV buses of a power supply end and a load end substation when the single-phase disconnection of the 110kV line occurs and comparing the voltage amplitude difference of the buses at two ends of the 110kV line, the load end 110kV substation transfers load power supply by adopting a closed-loop operation, the influence of the phase-lacking power supply of a transformer on a power grid and the load power supply is prevented, the 110kV transformer 110kV neutral point is prevented from being burnt, and the safe and stable operation of the power grid is ensured.

Description

Line disconnection relay protection method for comparing voltage difference between two sides of line and application

Technical Field

The invention relates to a line disconnection relay protection method for comparing voltage difference between two sides of a line and application, 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 technical scheme of relay protection, which uses the bus voltage of a load end of a line collected by a load end substation to judge and identify 110kV line single-phase disconnection and adopts a closed-loop operation to transfer load power supply.

Disclosure of Invention

The invention aims to provide a line disconnection relay protection method and application for comparing voltage differences on two sides of a line, which are characterized in that the single-phase disconnection of the 110kV line is identified by utilizing the fault characteristics of PT secondary voltages of 110kV buses of a power supply end and a load end substation when the single-phase disconnection of the 110kV line occurs and comparing the voltage amplitude difference of the buses at two ends of the 110kV line, the load end 110kV substation is used for transferring load power supply by adopting a closing and opening loop operation, so that the influence of the phase-lacking power supply of a transformer on a power grid and the load power supply is prevented, the 110kV transformer 110kV neutral point is prevented from being burnt, and the safe and stable operation of.

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

1.110kV line disconnection identification method

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

Collecting secondary A-phase voltage U of 110kV bus PT3 corresponding to 220kV transformer substation at power supply end_a1Phase U of B phase voltage_b1C phase voltage U_c1 Open delta voltage 3U_o11 # 110kV line power supply side circuit breaker 4DL switching-on position information;

simultaneously collecting PT secondary A-phase voltage U of I-section bus of 110kV transformer substation at load end_a2Phase U of B phase voltage_b2C phase voltage U_c2Open delta voltage 3U_o21DL switching-on position information of a circuit breaker on the load side of a No. 1 110kV power supply incoming line,

conditions are as follows:

(1)|U_a1|-|U_a2the voltage value difference of | is greater than the voltage setting value;

or | U_b1|-|U_b2The voltage value difference of | is greater than the voltage setting value;

or | U_c1|-|U_c2The voltage value difference of | is greater than the voltage setting value;

or |3U_o1|-|3U_o2The voltage value difference of | is greater than the voltage setting value;

(2) power end 110kV bus three-phase voltage symmetry normal of No. 1 110kV circuit, open triangle voltage 3U_oIs 0;

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

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

when the conditions are all met, identifying and judging that the No. 1 110kV power line is broken, after delaying t1, performing broken line protection on 110kV in No. 1 kV line protection of a load end 110kV transformer substation, starting up a breaker 2DL or 3DL of a standby power supply, tripping off a breaker 1DL on the load side of the No. 1 110kV power line, restoring a transformer without a power supply to the standby power line for supplying power, and starting a broken line alarm of the No. 1 110kV line;

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

Collecting secondary A-phase voltage U of 110kV bus PT4 corresponding to 220kV transformer substation at power supply end_a1Phase U of B phase voltage_b1C phase voltage U_c1

Open delta voltage 3U

_o12 # 110kV line power supply side circuit breaker 4DL switching-on position information;

simultaneously collecting PT secondary A-phase voltage U of II-section bus of 110kV transformer substation at load end_a2Phase U of B phase voltage_b2C phase voltage U_c2Open delta voltage 3U_o2No. 2 110kV power incoming line load side circuit breaker 1DL switching-on position information,

conditions are as follows:

(2) power end 110kV bus three-phase voltage symmetry normal of No. 2 110kV line, opening triangle voltage 3U_oIs 0;

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

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

when the conditions are all met, the No. 2 110kV power supply line is identified and judged to be broken, after the time delay t1, 110kV in the No. 2kV line protection of the load end 110kV transformer substation is protected to be broken, the on standby power supply circuit breaker 1DL or 3DL is started, the No. 2 110kV power supply line load side circuit breaker 2DL is tripped, the transformer losing the power supply is recovered to the standby power supply line to supply power, and meanwhile, the No. 2 110kV line breakage alarm is started.

The application of the line disconnection relay protection method for comparing the pressure difference between two sides of the line comprises the following steps: the line disconnection relay protection method for comparing the voltage difference between two sides of the line is applied to a single 110kV line disconnection protection device or a 110kV line protection device of a load end 110kV transformer substation.

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

the line disconnection relay protection method for comparing the pressure difference between two sides of the line comprises the following steps: the upper limit and the lower limit of the voltage setting value are 4-6V.

The line disconnection relay protection method for comparing the pressure difference between two sides of the line comprises the following steps: the t1 time is set to 0.1-0.2 seconds.

The line disconnection relay protection method for comparing the pressure difference between two sides of the line comprises the following steps: the voltage data on both sides does not require synchronization.

The application of the line disconnection relay protection method for comparing the pressure difference between two sides of the line is as follows: the 110kV line disconnection protection device or the 110kV line protection device has the following 110kV neutral point grounding mode: ungrounded or grounded.

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

1. the invention 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 voltage amplitude difference of the 110kV line two ends, identifies the 110kV line single-phase disconnection, and transfers load power supply by the load end 110kV substation through the ring closing and opening operation, thus being simple and easy.

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 amplitude difference at two sides of the line is compared to identify the disconnection of the 110kV line, and the load end 110kV transformer substation transfers the load power supply by adopting the ring closing and opening operation, so that the transformer losing the power supply is recovered to the relay protection scheme of the power supply on the standby power supply, the influence of the transformer phase-lacking power supply on the power grid and the load power supply can be effectively prevented, the 110kV transformer 110kV neutral point is prevented from being burnt, and the safe and stable operation of the power grid is facilitated.

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.

Drawings

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

fig. 2 is a first 110kV bus voltage vector diagram of 110kV line disconnection, wherein fig. 2(a) is a 110kV bus voltage vector diagram of a load side, and fig. 2(b) is a 110kV bus voltage vector diagram of a power side;

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

fig. 4 is a 110kV bus voltage vector diagram of 110kV line disconnection, wherein fig. 4(a) is a 110kV bus voltage vector diagram of the load side, and fig. 4(b) is a 110kV bus voltage vector diagram of the power side;

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

fig. 6 is a 110kV bus voltage vector diagram of 110kV line disconnection, wherein fig. 6(a) is a 110kV bus voltage vector diagram of the load side, and fig. 6(b) is a 110kV bus voltage vector diagram of the power side;

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:

1.110kV 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.

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. 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 110kV line is broken at a certain position and the load side is brokenAnd (3) grounding, such as phase A, and analyzing to obtain the 110kV bus voltage of the 110kV transformer substation at the load side as follows:

(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 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. 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.

(3) 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 2.110 kV 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 3.110 kV 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.

In view of the above situation, the present invention provides a line disconnection relay protection method for comparing the voltage difference between two sides of a line.

The power transmission and distribution network applied by the invention is a 110kV substation 110kV single-bus subsection primary main wiring (including a 110kV single-bus primary main wiring), a 110kV inner bridge wiring, a 110kV expansion inner bridge wiring, a 110kV line transformer bank wiring and other system networks. Taking a primary main connection of a 110kV single bus subsection as an example, the protection method of other primary main connections 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 electric substation 110kV side.

Aiming at the 110kV single-bus subsection primary main connection, voltage information of two sides of a line is transmitted through a 110kV line optical fiber channel in a power supply end 220kV transformer substation, voltage amplitude difference of the two sides of the line is compared to identify the line breakage of the 110kV line, and the load end 110kV transformer substation adopts a scheme of switching on and off loop operation to transfer load power supply to meet the field operation requirement.

The 110kV neutral point operation mode of all main transformers on the I section or II section of buses of the load end 110kV substation is as follows: a) grounding; b) not grounded, grounded through the gap. The 110kV line is provided with an optical fiber channel and line optical fiber differential protection.

Aiming at the primary main wiring of the 110kV single-bus subsection, 110kV single-phase broken line protection is implemented in 110kV line protection devices on two sides of a 110kV line.

The specific method of the invention is shown in figure 8:

1.110kV line disconnection identification method

simultaneously collecting PT secondary A-phase voltage U of I-section bus of 110kV transformer substation at load end_a2Phase U of B phase voltage_b2C phase voltage U_c2 Open delta voltage 3U_o21DL switching-on position information of a circuit breaker on the load side of a No. 1 110kV power supply incoming line,

conditions are as follows:

Open delta voltage 3U

simultaneously collecting PT secondary A-phase voltage U of II-section bus of 110kV transformer substation at load end_a2Phase U of B phase voltage_b2C phase voltage U_c2 Open delta voltage 3U_o2No. 2 110kV power incoming line load side circuit breaker 1DL switching-on position information,

conditions are as follows:

The reason that the circuit breakers 1DL or 2DL, 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 carries a load end 110kV substation, the bus voltage far away from the power supply incoming line can also sense the line disconnection information, and the action behavior of the device can be interfered; in addition, when a 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 tripping, the action behavior of the device can be interfered. The logic can be further optimized by adopting the condition that the circuit breakers on two sides of the incoming line of the 110kV power supply are in the switching-on position.

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 can be implemented in a single 110kV line disconnection protection device of a load end 110kV transformer substation or can also be implemented in a 110kV line protection device; the 110kV line protection device implemented in the 110kV transformer substation at the load end has the advantages that: no additional hardware devices are required.

The voltage setting value of the voltage value difference of the two secondary sides of the bus broken line phase PT on the two sides of the 110kV line is as follows:

(1)110kV bus PT secondary A-phase voltage value difference | U on two sides of 110kV line_a1|-|U_a2| U, B phase voltage value difference | U_b1|-|U_b2| and C phase voltage value difference | U_c1|-|U_c2The voltage setting value of | is as follows: setting according to the maximum unbalanced voltage greater than that in normal operation, and taking 4-6V;

(2) secondary voltage value difference |3U of PT opening triangle of 110kV bus on two sides of 110kV line_o1|-|3U_o2The voltage setting value of | is as follows: and when the voltage value is larger than the unbalanced voltage value in normal operation, taking 4-6V.

In the single-phase disconnection relay protection method for transferring load power supply by adopting ring closing and opening operation at the load end 110kV transformer substation, the setting value t1 of time is as follows: 0.1-0.2 second, and three-phase asynchronous time when the switch is closed is avoided.

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) 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 a 110kV line transformer bank; (6) other primary main connections.

If the 110kV transformer substation adopts primary main wiring of a 110kV line transformer set, a standby circuit breaker on the high-low voltage side of the 110kV transformer is adopted on the low-low voltage side of the load side transformer substation, and a power supply task is recovered.

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.

The invention adopts a method of independently arranging a 110kV line single-phase broken relay protection device in a load end substation or implementing the method in a 110kV spare power automatic switching device, and needs to add a new relay protection device or a new hardware interface; the protection device is implemented in the No. 1, No. 2 and No. 3 transformer protection devices, hardware equipment does not need to be added, and only the logic of single-phase disconnection of a 110kV line needs to be added.

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.

An example of the method of the invention is given below (taking fig. 9 as an example, the transformer 110kV neutral point operation mode is: ungrounded, grounded via 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 A phase single-phase disconnection fault of the No. 2 110kV power line occurs, the method is equivalent to pulling a disconnecting switch with load, an electric arc is generated at the disconnection moment, the electric arc cannot be extinguished, the electric arc is further developed to cause the A phase single-phase grounding of the line, and the protection starting action of the distance I section or the section II of the superior No. 2 power line jumps from a power side circuit breaker 5DL of the superior No. 2kV power line within the protection range of the distance I section or the section II of the superior No. 2 power line; after a first section or a second section of buses of a load end 110kV substation lose power, the fault at the phase A disconnection position of a No. 2 110kV power line disappears, and the upper level No. 2kV power line power side circuit breaker 5DL is delayed to be successfully superposed; however, the voltage inductance of the II-section bus of the load-side substation runs in a phase-loss manner, the PT secondary voltage of the 110kV bus 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 load-side line protection is disconnected, the No. 1 110kV standby power supply circuit breaker 1DL is started to be switched on, the No. 2 110kV power supply incoming line circuit breaker 2DL is switched off, and the No. 1, No. 2 and No. 3 transformers which lose power supplies are recovered to the standby No. 1 110kV power supply line for supplying power.

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 a disconnecting 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 protection starting action of the No. 1 power line at the section I or the section II of the distance between the No. 1 power line at the upper level jumps away from a circuit breaker 4DL at the power supply side of the No. 1 power line at the upper level because the distance between the No. 1 power line at the upper level and the section I or the; after the load end 110kV 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 bus voltage inductance of the load end transformer substation is in open-phase operation, the 110kV bus PT secondary voltage of the power end transformer substation is normal, the condition that the 1 # 110kV power line is single-phase broken is met, after the time delay t1, the 110kV line in the load end line protection is protected, after the 2 # 110kV standby power circuit breaker 2DL is started to be switched on, the 1 # 110kV power incoming line circuit breaker 1DL is switched off, and the 1 # transformer, the 2 # transformer and the 3 # transformer which lose power are recovered to the 2 # 110kV standby 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 protection starting action of the No. 1 superior 110kV power line is tripped out of a power supply side circuit breaker 4DL of the No. 1 superior power line within the protection range of the No. 1 superior power line from the No. 1 superior power; after a load end substation loses power, the fault of the phase disconnection position of a 110kV power line A disappears, and the superposition of a circuit breaker 4DL on the power side of a No. 1 delayed 110kV power line is successful; however, the I section bus voltage inductance of the load end transformer substation is in open-phase operation, the PT secondary voltage of the 110kV bus of the power end transformer substation is normal, the condition that the 1 # 110kV power line is single-phase broken is met, after the time delay t1, the 110kV line in the load end line protection is protected, after the 110kV standby power circuit breaker 3DL is started to be switched on, the 1 # 110kV power incoming line circuit breaker 1DL is switched off, and the 1 # and 2 # transformers losing power are enabled to be recovered to the 2 # 110kV standby power line for power supply.

No. 3.22 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 protection starting action of the section I or the section II of the distance between the upper level No. 2kV power line and the upper level No. 2 power line jumps away from the circuit breaker 5DL at the power supply side of the upper level No. 2 power line because the distance between the upper level No. 2kV power line and the section I or the; after a 110kV II section bus of a load end 110kV substation loses power, a fault at the phase A disconnection position of a 110kV power line disappears, a circuit breaker 5DL at the line power side of a No. 2 110kV power side line is successfully superposed, but voltage inductance of a II section bus of the load end 110kV substation is in open-phase operation, PT secondary voltage of the II section bus meets the condition 1 for identifying the 110kV line single-phase disconnection, the No. 2 110kV power line A phase single-phase disconnection fault is sent out after time delay t1, after a 110kV standby power circuit breaker 3DL is started after time delay t2, the No. 1 110kV power incoming circuit breaker 1DL is tripped, and a No. 3 transformer which loses power is recovered to a standby No. 2kV 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 A phase single-phase disconnection fault of the No. 2 110kV power line occurs, the method is equivalent to pulling a disconnecting 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 first section and the second section of the superior No. 2 power line is within the protection range of the first section or the second section of the superior No. 2 power line, so that the superior No. 2 power line is protected and started or the optical fiber differential protection action jumps away from a load side circuit breaker 5DL of the superior No. 2 power line; after the II-section bus of the load-end substation loses power, the fault at the phase-disconnection position A of the No. 2 110kV power line disappears, and the superposition of the No. 2 110kV power line load-side circuit breaker 5DL is successful after the time delay; however, the voltage inductance of the II-section bus of the load-side substation runs in a phase-loss mode, the PT secondary voltage of the 110kV bus 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 load-side line protection is protected, after the 110kV standby power supply circuit breaker 3DL is started to be switched on, the No. 2 110kV power supply line load-side circuit breaker 5DL is switched off, and the transformer without the power supply is enabled to be recovered to the standby No. 1 110kV power supply line for power supply.

Claims

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

method for identifying disconnection of 110kV line

Collecting the switching-on position information of a secondary A-phase voltage Ua1, a secondary B-phase voltage Ub1, a secondary C-phase voltage Uc1, an open triangular voltage 3Uo1 and a No. 1 110kV line power supply side circuit breaker 4DL corresponding to a 110kV bus PT3 of a power supply end 220kV transformer substation;

meanwhile, collecting the switching-on position information of a load side circuit breaker 1DL of a load side 110kV power supply incoming line load side circuit breaker 1, wherein the load side 110kV substation I section bus PT secondary A phase voltage Ua2, B phase voltage Ub2, C phase voltage Uc2, open delta voltage 3Uo2 and No. 1 110kV power supply incoming line load side circuit breaker,

conditions are as follows:

(1) the voltage value difference of the Ua 1-Ua 2 is larger than the voltage setting value;

or the voltage value difference of the absolute value Ub 1-absolute value Ub2 is larger than the voltage setting value;

or the voltage value difference of | Uc1| - | Uc2| is greater than the voltage setting value;

or the voltage value difference of |3Uo1| - |3Uo2| is greater than the voltage setting value;

(2) the three-phase voltage of a 110kV bus at a power end of a No. 1 110kV line is symmetrical and normal, and the open triangular voltage 3UO is 0;

Collecting the switching-on position information of a secondary A-phase voltage Ua1, a secondary B-phase voltage Ub1, a secondary C-phase voltage Uc1, an open triangular voltage 3Uo1 and a No. 2 110kV line power supply side circuit breaker 4DL corresponding to a 110kV bus PT4 of a power supply end 220kV transformer substation;

meanwhile, collecting the switching-on position information of a load side circuit breaker 1DL of a load side circuit-incoming line load side circuit breaker of a load end 110kV transformer substation II-section bus PT secondary A-phase voltage Ua2, B-phase voltage Ub2, C-phase voltage Uc2, open-delta voltage 3Uo2 and No. 2 110kV power supply,

conditions are as follows:

(2) the three-phase voltage of a 110kV bus at a power end of a No. 2 110kV line is symmetrical and normal, and the open triangular voltage 3UO is 0;

2. The line disconnection relay protection method for comparing the voltage difference between two sides of the line according to claim 1, wherein the upper and lower limits of the voltage setting value are 4-6V.

3. The line disconnection relay protection method for comparing the voltage difference across the line according to claim 1 or 2, wherein the time t1 is set to 0.1-0.2 seconds.

4. The method of line disconnect relay protection comparing differential voltage across a line as in claim 1, wherein the voltage data across the lines does not require synchronization.

5. The application of the line disconnection relay protection method for comparing the voltage difference between two sides of the line is characterized in that the line disconnection relay protection method for comparing the voltage difference between two sides of the line is applied to a 110kV line disconnection protection device or a 110kV line protection device of a 110kV transformer substation at a load end.

6. The application of the line disconnection relay protection method for comparing the voltage difference between two sides of the line according to claim 5, wherein the 110kV line disconnection protection device or the 110kV neutral point grounding mode of the transformer in the 110kV line protection device is as follows: ungrounded or grounded.