Main transformer microcomputer differential protection control circuit

Abstract

The utility model relates to the technical field of transformer protection control, and particularly discloses a main transformer microcomputer differential protection control circuit, which 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 positive electrode of a direct-current power supply of the main transformer differential protection high-voltage side circuit breaker tripping control circuit is connected with one end of a main transformer high-voltage circuit breaker differential protection tripping outlet relay normally-open contact, and the other end of an auxiliary normally-open contact of a main transformer high-voltage side circuit breaker is connected with one end of a main transformer high-voltage side circuit breaker opening coil. The other end of the main transformer high-voltage side circuit breaker opening coil is connected with the cathode of the direct-current power supply; the positive electrode of a direct-current power supply of the main transformer differential protection low-voltage side circuit breaker tripping control circuit is connected with one end of a main transformer low-voltage circuit breaker differential protection tripping outlet relay normally-open contact, and the other end of a main transformer low-voltage side circuit breaker opening coil is connected with the negative electrode of the direct-current power supply. The utility model ensures that the power supply system is safe and reliable.

Description

Technical Field

[0001] This utility model relates to the field of transformer protection and control technology, specifically to a microcomputer differential protection and control circuit for a main transformer. Background Technology

[0002] Transformers are crucial electrical equipment in power systems, and differential protection is the primary protection for the main transformer in a substation. When a severe (short-circuit) fault occurs within the differential protection zone between the current transformers on both sides of the main transformer, or when a fault occurs outside the transformer's differential protection zone, or when abnormal conditions such as main transformer power supply occur, unbalanced currents are generated. The differential protection should operate quickly and accurately to disconnect the fault and prevent the accident from escalating. In existing technologies, some main transformer differential protection control circuits are unreliable, and the differential protection cannot accurately and reliably implement its protection and control functions, leading to an expansion of the fault range and even damage to equipment such as the main transformer. Furthermore, unfamiliarity with the main transformer differential protection control circuit results in low fault handling efficiency and prolonged power outage time. Therefore, this paper provides a main transformer microprocessor-based differential protection control circuit and its operating method to solve the problems of low fault handling efficiency and prolonged power outage time caused by the unreliability of existing main transformer differential protection control circuits, thereby achieving tripping of the high and low voltage circuit breakers on both sides of the main transformer and ensuring the safety of the power supply system. Utility Model Content

[0003] To address the problems existing in the prior art, the purpose of this utility model is to provide a microcomputer differential protection control circuit for a main transformer. When a short circuit or other equipment fault occurs within the differential protection zone of the main transformer, it can reliably trip the high and low voltage circuit breakers on both sides of the main transformer, cut off the fault, and ensure the safety of the power supply system.

[0004] The technical solution adopted by this utility model to solve its technical problem is: a microcomputer differential protection control circuit for a main transformer, including a tripping control circuit for the high-voltage side circuit breaker of the main transformer differential protection and a tripping control circuit for the low-voltage side circuit breaker of the main transformer differential protection. The tripping control circuit for the high-voltage side circuit breaker of the main transformer differential protection includes a DC power supply, a normally open contact of the tripping output relay of the differential protection of the high-voltage side circuit breaker of the main transformer, a tripping pressure plate of the differential protection of the high-voltage side circuit breaker, a tripping holding relay one, an auxiliary normally open contact of the high-voltage side circuit breaker of the main transformer, and a tripping coil of the high-voltage side circuit breaker of the main transformer; the tripping control circuit for the low-voltage side circuit breaker of the main transformer differential protection includes a DC power supply, a normally open contact of the tripping output relay of the low-voltage side circuit breaker of the main transformer, a tripping pressure plate of the differential protection of the low-voltage side circuit breaker, a tripping holding relay two, an auxiliary normally open contact of the low-voltage side circuit breaker of the main transformer, and a tripping coil of the low-voltage side circuit breaker of the main transformer.

[0005] The positive terminal of the DC power supply of the trip control circuit of the high-voltage side circuit breaker of the main transformer differential protection is connected to one end of the normally open contact of the trip output relay of the main transformer high-voltage circuit breaker differential protection. The other end of the normally open contact of the trip output relay of the main transformer high-voltage circuit breaker differential protection is connected to one end of the trip pressure plate of the high-voltage side circuit breaker. The other end of the trip pressure plate of the high-voltage side circuit breaker differential protection is connected to one end of the coil of the trip holding relay. The other end of the coil of the trip holding relay 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 trip coil of the main transformer high-voltage side circuit breaker. The other end of the trip coil of the main transformer high-voltage side circuit breaker is connected to the negative terminal of the DC power supply.

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

[0007] Specifically, the primary wiring circuit of the main transformer high voltage side corresponding to the trip control circuit of the main transformer differential protection high voltage side circuit breaker is equipped with a main transformer high voltage side circuit breaker, and the primary wiring circuit of the main transformer low voltage side corresponding to the trip control circuit of the main transformer differential protection low voltage side circuit breaker is equipped 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 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 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. 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 together to the microcomputer protection and control device.

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

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

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

[0013] This utility model has the following beneficial effects:

[0014] The microcomputer differential protection control circuit for the main transformer designed in this utility model can quickly and accurately cut off the fault and prevent the accident from escalating when an unbalanced current is generated in the differential protection zone between the current transformers on both sides of the main transformer, or when a fault occurs outside the transformer differential zone, or when the main transformer is powered on. In addition, it can reduce the power outage time due to unfamiliarity with the main transformer differential protection control circuit and low fault handling efficiency, so as to ensure the safety and reliability of the power supply system. Attached Figure Description

[0015] Figure 1 This is a wiring diagram showing the connection of the same-name terminal of the main transformer microcomputer differential protection control circuit to the microcomputer protection and control device.

[0016] Figure 2 This is the circuit diagram of the tripping control circuit of the high-voltage side circuit breaker of the main transformer differential protection.

[0017] Figure 3 This is the circuit diagram of the tripping control circuit of the low-voltage side circuit breaker of the main transformer differential protection.

[0018] In the diagram: 1-35kV busbar; 2-10kV busbar; 3-Microcomputer protection and control device. Detailed Implementation

[0019] The technical solutions of the present utility model will be described in further detail below with reference to the accompanying drawings of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0020] like Figure 1As shown in the figure, this utility model embodiment discloses a wiring diagram of the main transformer microcomputer differential protection terminal connected to the microcomputer protection and control device 3 (the high and low voltage current transformers in the figure are both Y-type connected, and one phase is shown in the figure).

[0021] The primary wiring circuit of the main transformer high voltage side corresponding to the trip control circuit of the main transformer differential protection high voltage side circuit breaker is equipped with a main transformer high voltage side circuit breaker QF1, and the primary wiring circuit of the main transformer low voltage side corresponding to the trip control circuit of the main transformer differential protection low voltage side circuit breaker is equipped with a main transformer low voltage side circuit breaker QF2.

[0022] The power supply voltage of the primary circuit on the high-voltage side of the main transformer is 35kV1. The circuit breaker on the high-voltage side of the main transformer is connected to the primary circuit on the high-voltage side of the main transformer via the primary circuit of the current transformer TA1 on the high-voltage side. The power supply voltage of the primary circuit on the low-voltage side of the main transformer is 10kV2. The circuit breaker on the low-voltage side of the main transformer is connected to the primary circuit on the low-voltage side of the main transformer via the primary circuit of the current transformer TA2 on the low-voltage side. The secondary circuits of the current transformer TA2 on the low-voltage side and the secondary circuits of the current transformer TA1 on the high-voltage side are connected together to the microprocessor-based protection and control device 3.

[0023] For the high-voltage side current transformer TA1: P1 and P2 are the power supply and load side terminals of the primary winding of TA1, respectively; 1S1 and 1S2 are the secondary winding terminals of TA1, respectively. For the low-voltage side current transformer TA2: L1 and L2 are the power supply and load side terminals of the primary winding of TA2, respectively; 1K1 and 1K2 are the secondary winding terminals of TA2, respectively. 1S1 and 1K1 are connected to one end of the circuit breaker differential protection trip output relay coil, and 1S2 and 1K2 are connected to the other end of the circuit breaker differential protection trip output relay coil, and are grounded at terminal 1K2. The circuit breaker differential protection trip output relay is located on the differential protection plug-in board of the microcomputer protection and control device 3. In case of an abnormal fault, when a differential current is generated on the secondary side of the current transformers of the same phase on both the high and low voltage sides of the main transformer, and the set differential protection value is reached, the coil of the differential protection trip output relay is energized, and the relevant contacts are activated to connect the main transformer differential protection control circuit.

[0024] like Figures 2-3As shown, a microprocessor-based differential protection control circuit for a main transformer includes a tripping control circuit for the high-voltage side circuit breaker of the main transformer differential protection and a tripping control circuit for the low-voltage side circuit breaker of the main transformer differential protection. The tripping control circuit for the high-voltage side circuit breaker of the main transformer differential protection includes a DC power supply ±KM, a normally open contact BTJ-1 of the tripping output relay of the high-voltage side circuit breaker of the main transformer, a tripping pressure plate 1LP4 of the high-voltage side circuit breaker, a tripping holding relay TBJ1, and a tripping control circuit for the high-voltage side circuit breaker of the main transformer. The auxiliary normally open contact of circuit breaker QF1, the tripping coil TQ1 of the high-voltage side circuit breaker of the main transformer; the tripping control circuit of the low-voltage side circuit breaker of the main transformer differential protection includes a DC power supply ±KM, the normally open contact BTJ-4 of the tripping output relay of the differential protection of the low-voltage side circuit breaker of the main transformer, the tripping pressure plate 1LP6 of the differential protection of the low-voltage side circuit breaker, the tripping holding relay TBJ2, the auxiliary normally open contact of the low-voltage side circuit breaker QF2 of the main transformer, and the tripping coil TQ2 of the low-voltage side circuit breaker of the main transformer.

[0025] The positive terminal +KM of the DC power supply of the trip control circuit of the high-voltage side circuit breaker of the main transformer differential protection is connected to one end of the normally open contact BTJ-1 of the trip output relay of the high-voltage side circuit breaker of the main transformer. The other end of the normally open contact BTJ-1 of the trip output relay of the high-voltage side circuit breaker of the main transformer is connected to one end of the trip pressure plate 1LP4 of the high-voltage side circuit breaker. The other end of the trip pressure plate 1LP4 of the high-voltage side circuit breaker is connected to one end of the coil of the trip holding relay TBJ1. The other end of the coil of the trip holding relay TBJ1 is connected to one end of the auxiliary normally open contact of the high-voltage side circuit breaker QF1 of the main transformer. The other end of the auxiliary normally open contact of the high-voltage side circuit breaker QF1 of the main transformer is connected to one end of the trip coil TQ1 of the high-voltage side circuit breaker of the main transformer. The other end of the trip coil TQ1 of the high-voltage side circuit breaker of the main transformer is connected to the negative terminal -KM of the DC power supply.

[0026] The positive terminal +KM of the DC power supply of the trip control circuit of the low-voltage side circuit breaker of the main transformer differential protection is connected to one end of the normally open contact BTJ-4 of the trip output relay of the low-voltage side circuit breaker of the main transformer. The other end of the normally open contact BTJ-4 of the trip output relay of the low-voltage side circuit breaker of the main transformer is connected to one end of the trip pressure plate 1LP6 of the low-voltage side circuit breaker. The other end of the trip pressure plate 1LP6 of the low-voltage side circuit breaker is connected to one end of the coil of the second trip holding relay TBJ2. The other end of the coil of the second trip holding relay TBJ2 is connected to one end of the auxiliary normally open contact of the low-voltage side circuit breaker QF2 of the main transformer. The other end of the auxiliary normally open contact of the low-voltage side circuit breaker QF2 of the main transformer is connected to one end of the trip coil TQ2 of the low-voltage side circuit breaker of the main transformer. The other end of the trip coil TQ2 of the low-voltage side circuit breaker of the main transformer is connected to the negative terminal -KM of the DC power supply.

[0027] The self-holding contact TBJ1-1 of trip holding relay TBJ1 is connected in parallel to the positive terminal of the DC power supply and one end of the coil of trip holding relay TBJ1. The self-holding contact TBJ2-2 of trip holding relay TBJ2 is connected in parallel to the positive terminal of the DC power supply and one end of the coil of trip holding relay TBJ2.

[0028] The states of the normally open contacts BTJ-1 and BTJ-2 of the differential protection trip output relay of the main transformer high-voltage side circuit breaker and the main transformer low-voltage side circuit breaker are both controlled by the main transformer differential protection trip output relay. The coil of the main transformer differential protection trip output relay and its normally open contacts, the normally open contacts of the main transformer low-voltage side circuit breaker differential protection trip output relay, the self-holding contacts and coils of trip holding relay TBJ1 and trip holding relay TBJ2 are all located inside the microcomputer protection and control device 3.

[0029] The operating voltage of the DC power supply for the tripping control circuit of the high-voltage side circuit breaker of the main transformer differential protection and the DC power supply for the tripping control circuit of the low-voltage side circuit breaker of the main transformer differential protection is 220V.

[0030] The RCS-9671C device in the trip control circuit of the high-voltage side circuit breaker of the main transformer differential protection and the trip control circuit of the low-voltage side circuit breaker of the main transformer differential protection are located in the same microcomputer protection and control device 3.

[0031] The working principle of the main transformer microcomputer differential protection control circuit is as follows:

[0032] 1. When a circuit fault occurs in the equipment within the differential protection zone of the current transformers on both the high and low voltage sides of the main transformer, a differential current will be generated on the secondary side of the high voltage side current transformer TA1 and the low voltage side current transformer TA2 of the main transformer. When the differential current value reaches the differential protection setting value, the coil of the main transformer differential protection trip output relay will be energized.

[0033] 2. Specifically, when the normally open contact BTJ-1 of the differential protection trip output relay of the main transformer high-voltage circuit breaker closes, the positive terminal +KM of the DC power supply sequentially passes through the normally open contact BTJ-1 of the differential protection trip output relay of the high-voltage circuit breaker, the trip pressure plate 1LP4 of the differential protection of the high-voltage side circuit breaker, the coil of the trip holding relay TBJ1, the auxiliary normally open contact of the QF1 auxiliary normally open contact of the main transformer high-voltage side circuit breaker (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 QF1 auxiliary normally open contact of the main transformer high-voltage side circuit breaker is in the closed state), and the trip coil TQ1 of the main transformer high-voltage side circuit breaker, to the negative terminal -KM of the DC power supply of the main transformer. The trip coil TQ1 of the main transformer high-voltage side circuit breaker is energized. At the same time, the self-holding contact TBJ1-1 of the trip holding relay TBJ1 closes, ensuring that the QF1 of the main transformer high-voltage side circuit breaker completes the tripping action.

[0034] 3. Similarly, when the normally open contact BTJ-4 of the differential protection trip output relay of the main transformer low-voltage circuit breaker closes, the positive terminal +KM of the DC power supply passes sequentially through the normally open contact BTJ-4 of the differential protection trip output relay of the low-voltage circuit breaker, the trip pressure plate 1LP6 of the low-voltage side circuit breaker differential protection, the coil of the second trip holding relay TBJ2, the auxiliary normally open contact of the QF2 auxiliary normally open contact of the main transformer low-voltage side circuit breaker (when the main transformer is running normally, the low-voltage circuit breaker is in the closed position, and the auxiliary normally open contact of the QF2 auxiliary normally open contact of the main transformer low-voltage side circuit breaker is in the closed state), and the trip coil TQ2 of the main transformer low-voltage side circuit breaker, to the negative terminal -KM of the main transformer DC power supply. The trip coil TQ2 of the main transformer low-voltage side circuit breaker is energized. At the same time, the self-holding contact TBJ2-1 of the second trip holding relay TBJ2 closes, ensuring that the QF2 of the main transformer low-voltage side circuit breaker completes the tripping action.

[0035] This utility model is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this utility model, and any technical solutions that are the same as or similar to this utility model, fall within the protection scope of this utility model.

[0036] The technologies, shapes, and structures not described in detail in this utility model are all known technologies.

Claims

1. A microcomputer-based differential protection control circuit for a main transformer, characterized in that, The system includes a trip control circuit for the high-voltage side circuit breaker of the main transformer differential protection and a trip control circuit for the low-voltage side circuit breaker of the main transformer differential protection. The trip control circuit for the high-voltage side circuit breaker of the main transformer differential protection includes a DC power supply, a normally open contact of the trip output relay of the high-voltage side circuit breaker differential protection, a trip pressure plate of the high-voltage side circuit breaker differential protection, a trip holding relay one, an auxiliary normally open contact of the high-voltage side circuit breaker of the main transformer, and a trip coil of the high-voltage side circuit breaker of the main transformer. The trip control circuit for the low-voltage side circuit breaker of the main transformer differential protection includes a DC power supply, a normally open contact of the trip output relay of the low-voltage side circuit breaker differential protection, a trip pressure plate of the low-voltage side circuit breaker differential protection, a trip holding relay two, an auxiliary normally open contact of the low-voltage side circuit breaker of the main transformer, and a trip coil of the low-voltage side circuit breaker of the main transformer. The positive terminal of the DC power supply of the trip control circuit of the high-voltage side circuit breaker of the main transformer differential protection is connected to one end of the normally open contact of the trip output relay of the main transformer high-voltage circuit breaker differential protection. The other end of the normally open contact of the trip output relay of the main transformer high-voltage circuit breaker differential protection is connected to one end of the trip pressure plate of the high-voltage side circuit breaker. The other end of the trip pressure plate of the high-voltage side circuit breaker differential protection is connected to one end of the coil of the trip holding relay. The other end of the coil of the trip holding relay 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 trip coil of the main transformer high-voltage side circuit breaker. The other end of the trip coil of the main transformer high-voltage side circuit breaker is connected to the negative terminal of the DC power supply. The positive terminal of the DC power supply of the trip control circuit of the low-voltage side circuit breaker of the main transformer differential protection is connected to one end of the normally open contact of the trip output relay of the differential protection of the main transformer low-voltage circuit breaker. The other end of the normally open contact of the trip output relay of the differential protection of the main transformer low-voltage circuit breaker is connected to one end of the trip pressure plate of the low-voltage side circuit breaker. The other end of the trip pressure plate of the low-voltage side circuit breaker is connected to one end of the coil of the second trip holding relay. The other end of the coil of the second trip holding relay is connected to one end of the auxiliary normally open contact of the low-voltage side circuit breaker of the main transformer. The other end of the auxiliary normally open contact of the low-voltage side circuit breaker of the main transformer is connected to one end of the trip coil of the low-voltage side circuit breaker of the main transformer. The other end of the trip coil of the low-voltage side circuit breaker of the main transformer is connected to the negative terminal of the DC power supply.

2. The main transformer microcomputer differential protection control circuit according to claim 1, characterized in that, The primary wiring circuit of the main transformer high voltage side corresponding to the trip control circuit of the main transformer differential protection high voltage side circuit breaker is equipped with a main transformer high voltage side circuit breaker, and the primary wiring circuit of the main transformer low voltage side corresponding to the trip control circuit of the main transformer differential protection low voltage side circuit breaker is equipped with a main transformer low voltage side circuit breaker.

3. The main transformer microcomputer differential protection control circuit according to claim 2, characterized in that, The power supply voltage of the primary wiring circuit on the high-voltage side of the main transformer is 35kV. 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.

4. The main transformer microcomputer differential protection control circuit according to claim 3, 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 together to the microcomputer protection and control device.

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

6. The main transformer microcomputer differential protection control circuit according to claim 5, characterized in that, The states of the normally open contacts of the differential protection trip output relays of the main transformer high-voltage side circuit breaker and the main transformer low-voltage side circuit breaker are both controlled by the main transformer differential protection trip output relays. The coils of the main transformer differential protection trip output relays, as well as the normally open contacts of the main transformer high-voltage side circuit breaker differential protection trip output relays, the normally open contacts of the main transformer low-voltage side circuit breaker differential protection trip output relays, the self-holding contacts and coils of trip holding relay one and trip holding relay two, are all located inside the microcomputer protection and control device.

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

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