Main transformer microcomputer differential protection control circuit and working method

Abstract

The invention relates to the technical field of transformer protection control, and particularly discloses a main transformer microcomputer differential protection control circuit and a working method, and the circuit comprises a main transformer differential protection high-voltage side circuit breaker tripping control circuit and a main transformer differential protection low-voltage side circuit breaker tripping control circuit. The main transformer differential protection high-voltage side circuit breaker tripping control circuit comprises a direct-current power supply, a main transformer high-voltage side circuit breaker differential protection tripping outlet relay normally open contact, a high-voltage side circuit breaker differential protection tripping pressing plate, a tripping holding relay I, a main transformer high-voltage side circuit breaker auxiliary normally open contact and a main transformer high-voltage side circuit breaker opening coil; the main transformer differential protection low-voltage side circuit breaker tripping control circuit comprises a direct-current power supply, a main transformer low-voltage side circuit breaker differential protection tripping outlet relay normally open contact, a low-voltage side circuit breaker differential protection tripping pressing plate, a tripping holding relay II, a main transformer low-voltage side circuit breaker auxiliary normally open contact and a main transformer low-voltage side circuit breaker opening coil; safety and reliability of the power supply system are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of transformer protection control, and in particular to a main transformer microcomputer differential protection control circuit and a working method. Background Art

[0002] Transformers are important electrical equipment in power systems. Differential protection is the main protection of the main transformer in a substation. When a serious (short circuit) fault occurs in the differential protection zone between the current transformers on both sides of the main transformer or a fault occurs outside the transformer differential zone, as well as abnormal conditions such as power transmission of the main transformer, unbalanced current will be generated. The differential protection should act quickly and accurately to cut off the fault and avoid the expansion of the accident. In the prior art, some main transformer differential protection control circuits are unreliable, and the differential protection cannot accurately and reliably implement the protection control function, resulting in the expansion of the fault range and even damage to the main transformer and other equipment. In addition, the main transformer differential protection control circuit is not familiar, the fault handling efficiency is low, and the fault power outage time is prolonged. To this end, a main transformer microcomputer differential protection control circuit and a working method are provided to solve the problem of low fault handling efficiency and prolonged fault power outage time caused by the unreliable differential protection control circuit of the existing main transformer, so as to realize the protection tripping of high and low voltage circuit breakers on both sides of the main transformer and ensure the safety of the power supply system. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a main transformer microcomputer differential protection control circuit and working method, which can reliably realize the protection tripping of high and low voltage circuit breakers on both sides of the main transformer when equipment failures such as short circuit occur inside the main transformer differential protection zone, cut off the fault and ensure the safety of the power supply system.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a main transformer microcomputer differential protection control circuit, including a main transformer differential protection high-voltage side circuit breaker tripping control circuit and a main transformer differential protection low-voltage side circuit breaker tripping control circuit, wherein the main transformer differential protection high-voltage side circuit breaker tripping control circuit includes a DC power supply, a main transformer high-voltage side circuit breaker differential protection tripping output relay normally open contact, a high-voltage side circuit breaker differential protection tripping pressure plate, a tripping holding relay 1, an auxiliary normally open contact of the main transformer high-voltage side circuit breaker, and a main transformer high-voltage side circuit breaker tripping coil; the main transformer differential protection low-voltage side circuit breaker tripping control circuit includes a DC power supply, a main transformer low-voltage side circuit breaker differential protection tripping output relay normally open contact, a low-voltage side circuit breaker differential protection tripping pressure plate, a tripping holding relay 2, an auxiliary normally open contact of the main transformer low-voltage side circuit breaker, and a main transformer low-voltage side circuit breaker tripping coil.

[0005] Specifically, the positive pole of the DC power supply of the main transformer differential protection high-voltage side circuit breaker tripping control circuit is connected to one end of the normally open contact of the main transformer high-voltage circuit breaker differential protection tripping output relay, the other end of the normally open contact of the main transformer high-voltage circuit breaker differential protection tripping output relay is connected to one end of the high-voltage side circuit breaker differential protection tripping pressure plate, the other end of the high-voltage side circuit breaker differential protection tripping pressure plate is connected to one end of a trip holding relay coil, the other end of the trip holding relay coil is connected to one end of the auxiliary normally open contact of the main transformer high-voltage side circuit breaker, the other end of the auxiliary normally open contact of the main transformer high-voltage side circuit breaker is connected to one end of the main transformer high-voltage side circuit breaker opening coil, and the other end of the main transformer high-voltage side circuit breaker opening coil is connected to the negative pole of the DC power supply.

[0006] Specifically, the positive pole of the DC power supply of the main transformer differential protection low-voltage side circuit breaker tripping control circuit is connected to one end of the normally open contact of the main transformer low-voltage circuit breaker differential protection tripping output relay, the other end of the normally open contact of the main transformer low-voltage circuit breaker differential protection tripping output relay is connected to one end of the low-voltage side circuit breaker differential protection tripping pressure plate, the other end of the low-voltage side circuit breaker differential protection tripping pressure plate is connected to one end of the second coil of the trip holding relay, the other end of the second coil of the trip holding relay is connected to one end of the auxiliary normally open contact of the main transformer low-voltage side circuit breaker, the other end of the auxiliary normally open contact of the main transformer low-voltage side circuit breaker is connected to one end of the main transformer low-voltage side circuit breaker opening coil, and the other end of the main transformer low-voltage side circuit breaker opening coil is connected to the negative pole of the DC power supply.

[0007] Specifically, the main transformer high-voltage side primary wiring circuit corresponding to the main transformer differential protection high-voltage side circuit breaker tripping control circuit is provided with a main transformer high-voltage side circuit breaker, and the main transformer low-voltage side primary wiring circuit corresponding to the main transformer differential protection low-voltage side circuit breaker tripping control circuit is provided with a main transformer low-voltage side circuit breaker.

[0008] Specifically, the power supply voltage of the primary wiring circuit on the high-voltage side of the main transformer is 35 kV, and the circuit breaker on the high-voltage side of the main transformer is connected to the primary wiring side of the high-voltage side of the main transformer via the primary circuit of the current transformer on the high-voltage side of the main transformer.

[0009] Specifically, the power supply voltage of the primary wiring circuit on the low-voltage side of the main transformer is 10kV, the circuit breaker on the low-voltage side of the main transformer is connected to the primary wiring side of the low-voltage side of the main transformer through the primary circuit of the current transformer on the low-voltage side of the main transformer, and the secondary circuit of the current transformer on the low-voltage side of the main transformer and the secondary circuit of the current transformer on the high-voltage side of the main transformer are connected to the microcomputer protection and measurement and control device together.

[0010] Specifically, the self-holding contact of the trip-holding relay 1 is connected in parallel to the positive pole of the DC power supply and one end of the trip-holding relay 1 coil, and the self-holding contact of the trip-holding relay 2 is connected in parallel to the positive pole of the DC power supply and one end of the trip-holding relay 2 coil.

[0011] Specifically, the states of the normally open contacts of the differential protection tripping output relay of the main transformer high-voltage side circuit breaker and the normally open contacts of the differential protection tripping output relay of the main transformer low-voltage side circuit breaker are controlled by the main transformer differential protection tripping output relay, and the coil of the main transformer differential protection tripping output relay and its normally open contacts of the differential protection tripping output relay of the main transformer high-voltage side circuit breaker, the normally open contacts of the differential protection tripping output relay of the main transformer low-voltage side circuit breaker, the self-holding contacts and coils of the trip holding relay one, and the self-holding contacts and coils of the trip holding relay two are all located inside the microcomputer protection measurement and control device.

[0012] Specifically, the working power supply voltage of the DC power supply of the main transformer differential protection high-voltage side circuit breaker tripping control circuit and the DC power supply of the main transformer differential protection low-voltage side circuit breaker tripping control circuit are both 220V.

[0013] A working method of a main transformer microcomputer differential protection control circuit comprises the following steps:

[0014] S1. When a circuit fault occurs in the equipment within the differential protection zone of the current transformers on both sides of the main transformer, a differential current will be generated on the secondary sides of the current transformers on the high voltage side of the main transformer and the current transformers on the low voltage side of the main transformer. When the differential current value reaches the differential protection setting value, the coil of the main transformer differential protection tripping output relay is energized;

[0015] S2, the normally open contact of the tripping output relay of the differential protection of the main transformer high-voltage circuit breaker is closed and connected, and the positive pole of the DC power supply is sequentially connected through the normally open contact of the tripping output relay of the high-voltage circuit breaker differential protection, the tripping pressure plate of the high-voltage side circuit breaker differential protection, the first coil of the tripping holding relay, the auxiliary normally open contact of the high-voltage side circuit breaker of the main transformer, and the opening coil of the high-voltage side circuit breaker of the main transformer to the negative pole of the DC power supply of the main transformer, and the opening coil of the high-voltage side circuit breaker of the main transformer is energized. At the same time, the self-holding contact of the tripping holding relay is closed and connected to ensure that the high-voltage side circuit breaker of the main transformer completes the opening action;

[0016] S3. The normally open contact of the differential protection tripping output relay of the main transformer low-voltage circuit breaker is closed and connected. The positive pole of the DC power supply passes through the normally open contact of the differential protection tripping output relay of the low-voltage circuit breaker, the differential protection tripping pressure plate of the low-voltage side circuit breaker, the second coil of the tripping holding relay, the auxiliary normally open contact of the low-voltage side circuit breaker of the main transformer, the opening coil of the low-voltage side circuit breaker of the main transformer, and reaches the negative pole of the DC power supply of the main transformer. The opening coil of the low-voltage side circuit breaker of the main transformer is energized. At the same time, the self-holding contact of the second tripping holding relay is closed and connected to ensure that the low-voltage side circuit breaker of the main transformer completes the opening action.

[0017] The present invention has the following beneficial effects:

[0018] The main transformer microcomputer differential protection control circuit and working method designed by the present invention can generate unbalanced current when a serious (short circuit) fault occurs in the differential protection zone between the current transformers on both sides of the main transformer or a fault occurs outside the transformer differential zone, as well as abnormal conditions such as power transmission of the main transformer. The differential protection should act quickly and accurately to cut off the fault and avoid the expansion of the accident. In addition, the fault power outage time can be reduced to ensure safe and reliable power supply of the power supply system due to unfamiliarity with the main transformer differential protection control circuit and low fault handling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a wiring diagram of the same-named terminal of the main transformer microcomputer differential protection control circuit connected to the microcomputer protection measurement and control device.

[0020] Figure 2 It is the circuit diagram of the main transformer differential protection high-voltage side circuit breaker tripping control and the main transformer differential protection low-voltage side circuit breaker tripping control. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely further describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, an embodiment of the present invention discloses a wiring diagram of connecting the same-name terminals of a main transformer microcomputer differential protection to a microcomputer protection and measurement and control device (the high and low voltage current transformers in the figure are both Y-type wired, and one phase is drawn in the figure).

[0023] The main transformer high-voltage side primary wiring circuit corresponding to the main transformer differential protection high-voltage side circuit breaker tripping control circuit is provided with a main transformer high-voltage side circuit breaker QF1, and the main transformer low-voltage side primary wiring circuit corresponding to the main transformer differential protection low-voltage side circuit breaker tripping control circuit is provided with a main transformer low-voltage side circuit breaker QF2.

[0024] The power supply voltage of the primary wiring circuit on the high-voltage side of the main transformer is 35kV, and the circuit breaker on the high-voltage side of the main transformer is connected to the primary wiring side of the high-voltage side of the main transformer through the primary circuit of the current transformer TA1 on the high-voltage side of the main transformer. The power supply voltage of the primary wiring circuit on the low-voltage side of the main transformer is 10kV, and the circuit breaker on the low-voltage side of the main transformer is connected to the primary wiring side of the low-voltage side of the main transformer through the primary circuit of the current transformer TA2 on the low-voltage side of the main transformer, and the secondary circuit of the current transformer TA2 on the low-voltage side of the main transformer and the secondary circuit of the current transformer TA1 on the high-voltage side of the main transformer are connected to the microcomputer protection and measurement and control device together.

[0025] Main transformer high voltage side current transformer TA1: P1 and P2 are the connection terminals of the power supply side and load side of the primary winding of the main transformer high voltage side current transformer TA1, respectively, and 1S1 and 1S2 are the connection terminals of the secondary winding of the main transformer high voltage side current transformer TA1, respectively. Main transformer low voltage side current transformer TA2: L1 and L2 are the connection terminals of the power supply side and load side of the primary winding of the main transformer low voltage side current transformer TA2, respectively, and 1K1 and 1K2 are the connection terminals of the secondary winding of the main transformer low voltage side current transformer TA2, respectively. 1S1 and 1K1 are connected to one end of the relay coil of the circuit breaker differential protection tripping output, and 1S2 and 1K2 are connected to the other end of the relay coil of the circuit breaker differential protection tripping output, and are grounded at the connection terminal 1K2. The circuit breaker differential protection tripping output relay is on the differential protection plug-in board of the microcomputer protection and measurement and control device. In the case of abnormal fault, when differential current is generated on the secondary side of the current transformers with the same phase on both sides of the high and low voltage of the main transformer, and the set differential protection value is reached, the differential protection trip output relay coil is energized, and the relevant contacts are started to connect the main transformer differential protection control circuit.

[0026] like Figure 2 As shown, a main transformer microcomputer differential protection control circuit includes a main transformer differential protection high-voltage side circuit breaker trip control circuit and a main transformer differential protection low-voltage side circuit breaker trip control circuit. The main transformer differential protection high-voltage side circuit breaker trip control circuit includes a DC power supply ±KM, a main transformer high-voltage side circuit breaker differential protection trip output relay normally open contact BTJ-1, a high-voltage side circuit breaker differential protection trip pressure plate 1LP4, a trip holding relay TBJ1, a main transformer high-voltage side circuit breaker The auxiliary normally open contact of the circuit breaker QF1 on the high-voltage side of the main transformer, and the tripping coil TQ1 of the circuit breaker on the high-voltage side of the main transformer; the tripping control circuit of the circuit breaker on the low-voltage side of the main transformer differential protection includes the DC power supply ±KM, the normally open contact of the differential protection tripping output relay BTJ-4 of the circuit breaker on the low-voltage side of the main transformer, the differential protection tripping pressure plate 1LP6 of the circuit breaker on the low-voltage side, the tripping holding relay 2 TBJ2, the auxiliary normally open contact of the circuit breaker QF2 on the low-voltage side of the main transformer, and the tripping coil TQ2 of the circuit breaker on the low-voltage side of the main transformer.

[0027] The positive pole +KM of the DC power supply of the main transformer differential protection high-voltage side circuit breaker tripping control circuit is connected to one end of the normally open contact BTJ-1 of the main transformer high-voltage circuit breaker differential protection tripping output relay, the other end of the normally open contact BTJ-1 of the main transformer high-voltage circuit breaker differential protection tripping output relay is connected to one end of the high-voltage side circuit breaker differential protection tripping pressure plate 1LP4, the other end of the high-voltage side circuit breaker differential protection tripping pressure plate 1LP4 is connected to one end of the tripping holding relay TBJ1 coil, the other end of the tripping holding relay TBJ1 coil is connected to one end of the auxiliary normally open contact of the main transformer high-voltage side circuit breaker QF1, the other end of the auxiliary normally open contact of the main transformer high-voltage side circuit breaker QF1 is connected to one end of the main transformer high-voltage side circuit breaker opening coil TQ1, and the other end of the main transformer high-voltage side circuit breaker opening coil TQ1 is connected to the negative pole -KM of the DC power supply.

[0028] The positive pole +KM of the DC power supply of the main transformer differential protection low-voltage side circuit breaker tripping control circuit is connected to one end of the normally open contact BTJ-4 of the main transformer low-voltage circuit breaker differential protection tripping output relay, the other end of the normally open contact BTJ-4 of the main transformer low-voltage circuit breaker differential protection tripping output relay is connected to one end of the low-voltage side circuit breaker differential protection tripping pressure plate 1LP6, the other end of the low-voltage side circuit breaker differential protection tripping pressure plate 1LP6 is connected to one end of the tripping holding relay 2 TBJ2 coil, the other end of the tripping holding relay 2 TBJ2 coil is connected to one end of the auxiliary normally open contact of the main transformer low-voltage side circuit breaker QF2, the other end of the auxiliary normally open contact of the main transformer low-voltage side circuit breaker QF2 is connected to one end of the main transformer low-voltage side circuit breaker opening coil TQ2, and the other end of the main transformer low-voltage side circuit breaker opening coil TQ2 is connected to the negative pole -KM of the DC power supply.

[0029] The self-holding contact TBJ1-1 of the trip holding relay TBJ1 is connected in parallel to the positive pole of the DC power supply and one end of the coil of the trip holding relay TBJ1, and the self-holding contact TBJ2-2 of the trip holding relay TBJ2 is connected in parallel to the positive pole of the DC power supply and one end of the coil of the trip holding relay TBJ2.

[0030] The states of the normally open contacts BTJ-1 of the differential protection tripping output relay of the circuit breaker on the high-voltage side of the main transformer and the normally open contacts BTJ-2 of the differential protection tripping output relay of the circuit breaker on the low-voltage side of the main transformer are controlled by the differential protection tripping output relay of the main transformer. The coil of the differential protection tripping output relay of the main transformer and its normally open contacts of the differential protection tripping output relay of the main transformer, the normally open contacts of the differential protection tripping output relay of the circuit breaker on the low-voltage side of the main transformer, the self-holding contacts and coils of the tripping holding relay 1 TBJ1, and the self-holding contacts and coils of the tripping holding relay 2 TBJ2 are all located inside the microcomputer protection and measurement and control device.

[0031] The working power supply voltage of the DC power supply of the high-voltage side circuit breaker tripping control circuit of the main transformer differential protection and the DC power supply of the low-voltage side circuit breaker tripping control circuit of the main transformer differential protection are both 220V.

[0032] The RCS-9671C device in the main transformer differential protection high voltage side circuit breaker tripping control circuit and the main transformer differential protection low voltage side circuit breaker tripping control circuit is located in the same microcomputer protection measurement and control device.

[0033] The working principle of the main transformer microcomputer differential protection control circuit is as follows:

[0034] 1. When a circuit fault occurs in the equipment within the differential protection zone of the current transformers on both sides of the main transformer, a differential current will be generated on the secondary sides of the current transformer TA1 on the high voltage side of the main transformer and the current transformer TA2 on the low voltage side of the main transformer. When the differential current value reaches the differential protection setting value, the coil of the main transformer differential protection tripping output relay is energized.

[0035] 2. Among them, the normally open contact BTJ-1 of the differential protection tripping output relay of the main transformer high-voltage circuit breaker is closed and connected, and the positive pole +KM of the DC power supply is successively transmitted through the normally open contact BTJ-1 of the differential protection tripping output relay of the high-voltage circuit breaker, the differential protection tripping pressure plate 1LP4 of the high-voltage side circuit breaker, the tripping holding relay TBJ1 coil, the auxiliary normally open contact of the high-voltage side circuit breaker QF1 of the main transformer (when the main transformer is operating normally, the high-voltage circuit breaker is in the closed position, and the auxiliary normally open contact of the high-voltage side circuit breaker QF1 of the main transformer is in the closed and connected state), and the main transformer high-voltage side circuit breaker opening coil TQ1, to the negative pole -KM of the main transformer DC power supply, and the main transformer high-voltage side circuit breaker opening coil TQ1 is energized. At the same time, the self-holding contact TBJ1-1 of the tripping holding relay TBJ1 is closed and connected, ensuring that the high-voltage side circuit breaker QF1 of the main transformer completes the opening action.

[0036] 3. Similarly, the normally open contact BTJ-4 of the differential protection tripping output relay of the main transformer low-voltage circuit breaker is closed and connected, and the positive pole +KM of the DC power supply is successively transmitted through the normally open contact BTJ-4 of the low-voltage circuit breaker differential protection tripping output relay, the low-voltage side circuit breaker differential protection tripping pressure plate 1LP6, the tripping holding relay 2 TBJ2 coil, the auxiliary normally open contact of the main transformer low-voltage side circuit breaker QF2 (when the main transformer is operating normally, the low-voltage circuit breaker is in the closed position, and the auxiliary normally open contact of the main transformer low-voltage side circuit breaker QF2 is in the closed and connected state), the main transformer low-voltage side circuit breaker opening coil TQ2, to the negative pole -KM of the main transformer DC power supply, and the main transformer low-voltage side circuit breaker opening coil TQ2 is energized. At the same time, the self-holding contact TBJ2-1 of the tripping holding relay 2 TBJ2 is closed and connected, ensuring that the main transformer low-voltage side circuit breaker QF2 completes the opening action.

[0037] The present invention is not limited to the above-mentioned implementation modes, and anyone should be aware that any structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention.

[0038] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A main transformer microcomputer differential protection control circuit, characterized in that: It includes a main transformer differential protection high-voltage side circuit breaker trip control circuit and a main transformer differential protection low-voltage side circuit breaker trip control circuit. The main transformer differential protection high-voltage side circuit breaker trip control circuit includes a DC power supply, a main transformer high-voltage side circuit breaker differential protection trip output relay normally open contact, a high-voltage side circuit breaker differential protection trip pressure plate, a trip holding relay 1, an auxiliary normally open contact of the main transformer high-voltage side circuit breaker, and a main transformer high-voltage side circuit breaker trip coil; the main transformer differential protection low-voltage side circuit breaker trip control circuit includes a DC power supply, a main transformer low-voltage side circuit breaker differential protection trip output relay normally open contact, a low-voltage side circuit breaker differential protection trip pressure plate, a trip holding relay 2, an auxiliary normally open contact of the main transformer low-voltage side circuit breaker, and a main transformer low-voltage side circuit breaker trip coil.

2. The main transformer microcomputer differential protection control circuit according to claim 1 is characterized in that: The positive pole of the DC power supply of the main transformer differential protection high-voltage side circuit breaker tripping control circuit is connected to one end of the normally open contact of the main transformer high-voltage circuit breaker differential protection tripping output relay, the other end of the normally open contact of the main transformer high-voltage circuit breaker differential protection tripping output relay is connected to one end of the high-voltage side circuit breaker differential protection tripping pressure plate, the other end of the high-voltage side circuit breaker differential protection tripping pressure plate is connected to one end of a trip holding relay coil, the other end of the trip holding relay coil is connected to one end of the auxiliary normally open contact of the main transformer high-voltage side circuit breaker, the other end of the auxiliary normally open contact of the main transformer high-voltage side circuit breaker is connected to one end of the main transformer high-voltage side circuit breaker opening coil, and the other end of the main transformer high-voltage side circuit breaker opening coil is connected to the negative pole of the DC power supply.

3. The main transformer microcomputer differential protection control circuit according to claim 1 is characterized in that: The positive pole of the DC power supply of the main transformer differential protection low-voltage side circuit breaker tripping control circuit is connected to one end of the normally open contact of the main transformer low-voltage circuit breaker differential protection tripping output relay, the other end of the normally open contact of the main transformer low-voltage circuit breaker differential protection tripping output relay is connected to one end of the low-voltage side circuit breaker differential protection tripping pressure plate, the other end of the low-voltage side circuit breaker differential protection tripping pressure plate is connected to one end of the second coil of the trip holding relay, the other end of the second coil of the trip holding relay is connected to one end of the auxiliary normally open contact of the main transformer low-voltage side circuit breaker, the other end of the auxiliary normally open contact of the main transformer low-voltage side circuit breaker is connected to one end of the main transformer low-voltage side circuit breaker opening coil, and the other end of the main transformer low-voltage side circuit breaker opening coil is connected to the negative pole of the DC power supply.

4. The main transformer microcomputer differential protection control circuit according to claim 1 is characterized in that: The main transformer high-voltage side primary wiring circuit corresponding to the main transformer differential protection high-voltage side circuit breaker tripping control circuit is provided with a main transformer high-voltage side circuit breaker, and the main transformer low-voltage side primary wiring circuit corresponding to the main transformer differential protection low-voltage side circuit breaker tripping control circuit is provided with a main transformer low-voltage side circuit breaker.

5. The main transformer microcomputer differential protection control circuit according to claim 4 is characterized in that: The power supply voltage of the primary wiring circuit on the high-voltage side of the main transformer is 35 kV, and the circuit breaker on the high-voltage side of the main transformer is connected to the primary wiring side of the high-voltage side of the main transformer via the primary circuit of the current transformer on the high-voltage side of the main transformer.

6. The main transformer microcomputer differential protection control circuit according to claim 5 is characterized in that: The power supply voltage of the primary wiring circuit on the low-voltage side of the main transformer is 10kV. The circuit breaker on the low-voltage side of the main transformer is connected to the primary wiring side of the low-voltage side of the main transformer through the primary circuit of the current transformer on the low-voltage side of the main transformer. The secondary circuit of the current transformer on the low-voltage side of the main transformer and the secondary circuit of the current transformer on the high-voltage side of the main transformer are connected to the microcomputer protection and measurement and control device together.

7. The main transformer microcomputer differential protection control circuit according to claim 1 is characterized in that: The self-holding contact of the trip-holding relay 1 is connected in parallel to the positive pole of the DC power supply and one end of the trip-holding relay 1 coil, and the self-holding contact of the trip-holding relay 2 is connected in parallel to the positive pole of the DC power supply and one end of the trip-holding relay 2 coil.

8. The main transformer microcomputer differential protection control circuit according to claim 7 is characterized in that: The states of the normally open contacts of the differential protection tripping output relay of the main transformer high-voltage side circuit breaker and the normally open contacts of the differential protection tripping output relay of the main transformer low-voltage side circuit breaker are controlled by the main transformer differential protection tripping output relay. The coil of the main transformer differential protection tripping output relay and its normally open contacts of the differential protection tripping output relay of the main transformer high-voltage side circuit breaker, the normally open contacts of the differential protection tripping output relay of the main transformer low-voltage side circuit breaker, the self-holding contacts and coils of the tripping holding relay 1, and the self-holding contacts and coils of the tripping holding relay 2 are all located inside the microcomputer protection measurement and control device.

9. The main transformer microcomputer differential protection control circuit according to claim 1 is characterized in that: The working power supply voltage of the DC power supply of the main transformer differential protection high-voltage side circuit breaker tripping control circuit and the DC power supply of the main transformer differential protection low-voltage side circuit breaker tripping control circuit are both 220V.

10. The working method of the main transformer microcomputer differential protection control circuit according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. When a circuit fault occurs in the equipment within the differential protection zone of the current transformers on both sides of the main transformer, a differential current will be generated on the secondary sides of the current transformers on the high voltage side of the main transformer and the current transformers on the low voltage side of the main transformer. When the differential current value reaches the differential protection setting value, the coil of the main transformer differential protection tripping output relay is energized; S2, the normally open contact of the tripping output relay of the differential protection of the main transformer high-voltage circuit breaker is closed and connected, and the positive pole of the DC power supply is sequentially connected through the normally open contact of the tripping output relay of the high-voltage circuit breaker differential protection, the tripping pressure plate of the high-voltage side circuit breaker differential protection, the first coil of the tripping holding relay, the auxiliary normally open contact of the high-voltage side circuit breaker of the main transformer, and the opening coil of the high-voltage side circuit breaker of the main transformer to the negative pole of the DC power supply of the main transformer, and the opening coil of the high-voltage side circuit breaker of the main transformer is energized. At the same time, the self-holding contact of the tripping holding relay is closed and connected to ensure that the high-voltage side circuit breaker of the main transformer completes the opening action; S3. The normally open contact of the differential protection tripping output relay of the main transformer low-voltage circuit breaker is closed and connected. The positive pole of the DC power supply passes through the normally open contact of the differential protection tripping output relay of the low-voltage circuit breaker, the differential protection tripping pressure plate of the low-voltage side circuit breaker, the second coil of the tripping holding relay, the auxiliary normally open contact of the low-voltage side circuit breaker of the main transformer, the opening coil of the low-voltage side circuit breaker of the main transformer, and reaches the negative pole of the DC power supply of the main transformer. The opening coil of the low-voltage side circuit breaker of the main transformer is energized. At the same time, the self-holding contact of the second tripping holding relay is closed and connected to ensure that the low-voltage side circuit breaker of the main transformer completes the opening action.

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