A substation transformer backup phase automatic switching circuit

Abstract

The application discloses a substation transformer spare phase automatic switching loop, characterized in that: collecting main transformer normal phase related primary equipment signals, the main transformer normal phase including transformer A phase, transformer B phase and transformer C phase, judging whether the spare phase is put into based on the three-phase state of the main transformer normal phase, when the spare phase is put into, switching the non-electric quantity signal of the spare phase and the current signal of the spare phase to the control protection circuit of the relay protection. The main transformer normal phase related primary equipment signals include the position state of the main transformer high-voltage side knife switch, the position state of the main transformer high-voltage side bypass knife switch and the position state of the main transformer medium-voltage side knife switch. The conditions for judging whether the spare phase is put into include: when the corresponding phase of the main transformer normal phase on both sides of the bypass knife switch is closed, it indicates that the corresponding phase of the main transformer normal phase is withdrawn, and at the same time, the spare phase is in the put-in state; and only when the three phases of the main transformer normal phase are in the put-in state, the spare phase is withdrawn.

Description

Technical Field

[0001] This invention relates to an automatic switching circuit for standby phases of a substation transformer, belonging to the technical field of automatic switching of standby phases in substations. Background Technology

[0002] Currently, ultra-high voltage substations typically use phase-splitting transformers. To ensure reliable system operation, a backup phase for the main transformer is usually set up. There is an electrical primary structure that can quickly switch the backup phase, which can quickly realize the switching of the primary system of the backup phase transformer. However, in the secondary electrical circuit, it is still necessary to remove the original cable connection and reconnect it to the new main transformer terminal box, which consumes a lot of time and prolongs the system failure time. Or, due to human error in secondary wiring, it can lead to on-site accidents, resulting in poor economic efficiency. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an automatic switching circuit for standby phases of substation transformers, which can shorten working time, reduce the impact on the power system, and has high versatility and flexibility.

[0004] To achieve the above objectives, the present invention provides an automatic switching circuit for standby phases of a substation transformer. It collects primary equipment signals related to the normal phases of the main transformer, which include transformer A phase, transformer B phase, and transformer C phase. Based on the three-phase status of the normal phases of the main transformer, it determines whether the standby phase is engaged. When the standby phase is engaged, it switches the non-electrical quantity signals and current signals of the standby phase to the control and protection circuit of the relay protection.

[0005] Prior to this, the normal phase-related primary equipment signals of the main transformer include the position status of the main transformer high-voltage side disconnect switch, the position status of the main transformer high-voltage side bypass disconnect switch, and the position status of the main transformer medium-voltage side disconnect switch.

[0006] Priority is given to the following conditions for determining whether the standby phase is engaged: when both the high-voltage side bypass switch and the medium-voltage side bypass switch of the main transformer are closed, it indicates that the corresponding phase of the main transformer's normal phase is out, and the standby phase is engaged; the standby phase is out if and only if both the high-voltage side bypass switch and the medium-voltage side bypass switch of the main transformer are open, and all three phases of the transformer's normal phase are engaged.

[0007] Priority is given to the main transformer high-voltage side bypass disconnectors, which include disconnectors 89T-C2 and 89T-C3. The high-voltage C-phase system of the substation is connected to the high-voltage bypass bus after disconnectors 89T-C2 and 89T-C3 are connected in series.

[0008] The main transformer high-voltage side disconnector includes disconnector 89T-C1. After the high-voltage C-phase system of the substation is connected in series with disconnector 89T-C1, it is connected to the C-phase bushing of the transformer high-voltage side.

[0009] The medium-voltage side bypass switch of the main transformer includes medium-voltage switch 89T-C4 and medium-voltage switch 89T-C5. The medium-voltage C-phase system of the substation is connected to the medium-voltage C-phase bushing of the transformer after the medium-voltage switch 89T-C4 is connected in series. The medium-voltage C-phase system of the substation is connected to the medium-voltage bypass bus after the medium-voltage switch 89T-C5 is connected in series. The low-voltage C-phase bushing of the transformer is connected to the B phase of the low-voltage bypass bus through a jumper. The low-voltage C-phase bushing of the transformer is connected to the C phase of the low-voltage bypass bus through a jumper. The neutral point of the C phase of the transformer is connected to the neutral point bus through a jumper in series. The neutral point bus is grounded after a single-phase CT in series.

[0010] When disconnectors 89T-C2, 89T-C3 and medium-voltage disconnector 89T-C5 are all closed, it indicates that the C phase of the transformer is out of service.

[0011] When disconnectors 89T-C2, 89T-C3, and medium-voltage disconnector 89T-C5 are all disconnected, it indicates that the C phase of the transformer is in operation.

[0012] Priority is given to the main transformer high-voltage side bypass disconnectors, which include disconnectors 89T-B2 and 89T-B3. The high-voltage B-phase system of the substation is connected to the high-voltage bypass bus after disconnectors 89T-B2 and 89T-B3 are connected in series.

[0013] The main transformer high-voltage side disconnector includes disconnector 89T-B1. After the high-voltage B-phase system of the substation is connected in series with disconnector 89T-B1, it is connected to the high-voltage side B-phase bushing of the transformer.

[0014] The medium-voltage side bypass switch of the main transformer includes medium-voltage switch 89T-B4 and medium-voltage switch 89T-B5. The medium-voltage B-phase system of the substation is connected to the medium-voltage side B-phase bushing of the transformer after the medium-voltage switch 89T-B4 is connected in series. The medium-voltage B-phase system of the substation is connected to the medium-voltage bypass bus after the medium-voltage switch 89T-B5 is connected in series. The low-voltage side B-phase bushing of the transformer is connected to the B-phase of the low-voltage bypass bus through a jumper. The low-voltage side B-phase bushing of the transformer is connected to the B-phase of the low-voltage bypass bus through a jumper. The neutral point of the B-phase of the transformer is connected to the neutral point bus through a jumper in series. The neutral point bus is connected to the ground through a single-phase CT in series.

[0015] When disconnectors 89T-B2, 89T-B3 and medium-voltage disconnector 89T-B5 are all closed, it indicates that phase B of the transformer is out of service.

[0016] When disconnectors 89T-B2, 89T-B3, and medium-voltage disconnector 89T-B5 are all disconnected, it indicates that phase B of the transformer is in operation.

[0017] Priority is given to the main transformer high-voltage side bypass disconnectors, which include disconnectors 89T-A2 and 89T-A3. After disconnectors 89T-A2 and 89T-A3 are connected in series in the high-voltage A-phase system of the substation, they are electrically connected to the high-voltage bypass bus.

[0018] The main transformer high-voltage side disconnector includes disconnector 89T-A1. The high-voltage A-phase system of the substation is connected in series with disconnector 89T-A1 and then connected to the A-phase bushing of the high-voltage side of the transformer.

[0019] The medium-voltage side bypass switch of the main transformer includes medium-voltage switch 89T-A4 and medium-voltage switch 89T-A5. The medium-voltage A-phase system of the substation is connected to the A-phase bushing of the transformer medium-voltage side after the medium-voltage switch 89T-A4 is connected in series. The medium-voltage A-phase system of the substation is connected to the medium-voltage bypass bus after the medium-voltage switch 89T-A5 is connected in series. The A-phase bushing of the transformer low-voltage side is connected to the B phase of the low-voltage bypass bus through a jumper. The A-phase bushing of the transformer low-voltage side is connected to the A phase of the low-voltage bypass bus through a jumper. The neutral point of the transformer A-phase is connected to the neutral point bus through a jumper. The neutral point bus is connected to the ground after a single-phase CT is connected in series.

[0020] When disconnectors 89T-A2, 89T-A3, and medium-voltage disconnector 89T-A5 are all closed, it indicates that phase A of the transformer is out of service.

[0021] When disconnectors 89T-A2, 89T-A3, and medium-voltage disconnector 89T-A5 are all disconnected, it indicates that phase A of the transformer is in operation.

[0022] Priority is given to the following: the standby phase high-voltage side bushing is electrically connected to the high-voltage bypass bus; the standby phase low-voltage side bushing is electrically connected to phase A of the low-voltage bypass bus via a jumper; the standby phase low-voltage side bushing is electrically connected to phase B of the low-voltage bypass bus via a jumper; the standby phase medium-voltage side bushing is electrically connected to the medium-voltage bypass bus; the standby phase neutral point is connected to the neutral point bus via a jumper; and the neutral point bus is connected to the ground via a single-phase CT connected in series.

[0023] If at least one of the three conditions—transformer A phase decommissioning, transformer B phase decommissioning, and transformer C phase decommissioning—is met, the standby phase will be activated and put into operation.

[0024] If all three conditions for transformer A phase to operate, transformer B phase to operate, and transformer C phase to operate are met, then the standby phase will be taken out of operation.

[0025] Priority is given to the control and protection circuit of the relay protection, which includes the normally closed contact 75XA of the transformer A phase switching relay, transformer A phase non-electrical quantity 1, transformer A phase non-electrical quantity 2, the first coil of the 130A relay, and the second coil of the 130A relay. The positive signal power supply is connected in series with the normally closed contact 75XA of the transformer A phase switching relay, transformer A phase non-electrical quantity 1, and the first coil of the 130A relay, and then electrically connected to the negative signal power supply. The transformer A phase non-electrical quantity 2 is connected in series with the second coil of the 130A relay and then connected in parallel with the transformer A phase non-electrical quantity 1 and the first coil of the 130A relay.

[0026] The control and protection circuit of the relay protection also includes the normally closed contact 75XB of the transformer B phase switching relay, transformer B phase non-electrical quantity 1, transformer B phase non-electrical quantity 2, the first coil of the 130B relay and the second coil of the 130B relay. The signal positive power supply is connected in series with the normally closed contact 75XB of the transformer B phase switching relay, transformer B phase non-electrical quantity 1 and the first coil of the 130B relay and then electrically connected to the signal negative power supply. The transformer B phase non-electrical quantity 2 is connected in series with the second coil of the 130B relay and then connected in parallel with the transformer B phase non-electrical quantity 1 and the first coil of the 130B relay.

[0027] The control and protection circuit of the relay protection also includes the normally closed contact 75XC of the transformer C-phase switching relay, transformer C-phase non-electrical quantity 1, transformer C-phase non-electrical quantity 2, the first coil of the 130C relay and the second coil of the 130C relay. The signal positive power supply is connected in series with the normally closed contact 75XC of the transformer C-phase switching relay, transformer C-phase non-electrical quantity 1 and the first coil of the 130C relay and then electrically connected to the signal negative power supply. The transformer C-phase non-electrical quantity 2 is connected in series with the second coil of the 130C relay and then connected in parallel with the transformer C-phase non-electrical quantity 1 and the first coil of the 130C relay.

[0028] The control and protection circuit of the relay protection also includes the normally open contact 75X of the standby phase switching relay, standby phase non-electrical quantity 1, standby phase non-electrical quantity 2, the first coil of the 130S relay and the second coil of the 130S relay. The signal positive power supply is connected in series with the normally closed contact 75X of the standby phase switching relay, standby phase non-electrical quantity 1 and the first coil of the 130S relay and then electrically connected to the signal negative power supply. The standby phase non-electrical quantity 2 is connected in series with the second coil of the 130S relay and then connected in parallel with the standby phase non-electrical quantity 1 and the first coil of the 130S relay.

[0029] Preferred, the transformer A-phase switching relay, transformer B-phase switching relay, transformer C-phase switching relay, and standby phase switching relay are dual-position magnetic latching relays.

[0030] The beneficial effects achieved by this invention are as follows:

[0031] Compared with the prior art, the circuit described in this invention enables automatic switching of protection and control functions, saves the additional secondary wiring work in the standby phase switching, improves the efficiency of standby phase switching, and reduces the power system outage time. Attached Figure Description

[0032] Figure 1 This is the primary three-wire electrical diagram of the phase transformers and standby phases in the substation;

[0033] Figure 2 This is the internal logic diagram of the measurement and control logic output contacts of this invention;

[0034] Figure 3 This is the zero-differential protection current switching circuit diagram of the present invention;

[0035] Figure 4 This is the non-electrical quantity protection signal switching circuit diagram of the present invention.

[0036] Among them, 75X is the standby phase switching relay, 75XA is the A phase switching relay, 75XB is the B phase switching relay, and 75XC is the C phase switching relay. Detailed Implementation

[0037] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0038] An automatic switching circuit for standby phases of a substation transformer collects primary equipment signals related to the normal phases of the main transformer. The normal phases of the main transformer include transformer phase A, transformer phase B, and transformer phase C. Based on the three-phase status of the normal phases of the main transformer, it determines whether the standby phase is engaged. When the standby phase is engaged, it switches the non-electrical quantity signals and current signals of the standby phase to the control and protection circuit of the relay protection.

[0039] Furthermore, in this embodiment, the normal phase-related primary equipment signals of the main transformer include the position status of the main transformer high-voltage side disconnect switch, the position status of the main transformer high-voltage side bypass disconnect switch, and the position status of the main transformer medium-voltage side disconnect switch.

[0040] Furthermore, in this embodiment, the conditions for determining whether the standby phase is engaged include: when both the high-voltage side bypass switch and the medium-voltage side bypass switch of the main transformer are closed, it indicates that the corresponding phase of the main transformer normal phase is out, and the standby phase is engaged; the standby phase is out if and only if both the high-voltage side bypass switch and the medium-voltage side bypass switch of the main transformer are open, and all three phases of the transformer normal phase are engaged.

[0041] Furthermore, in this embodiment, the high-voltage side bypass switch of the main transformer includes switch 89T-C2 and switch 89T-C3. The high-voltage C-phase system of the substation is connected to the high-voltage bypass bus after the high-voltage switch 89T-C2 and switch 89T-C3 are connected in series.

[0042] The main transformer high-voltage side disconnector includes disconnector 89T-C1. The high-voltage C-phase system of the substation is connected in series with disconnector 89T-C1 and then connected to the C-phase bushing of the transformer high-voltage side. The C-phase bushing of the transformer high-voltage side is connected in series with a surge arrester and then grounded. Disconnector 89T-C1 is connected in series with a grounding switch and then grounded.

[0043] The medium-voltage side bypass switch of the main transformer includes medium-voltage switch 89T-C4 and medium-voltage switch 89T-C5. The medium-voltage C-phase system of the substation is connected to the medium-voltage C-phase bushing of the transformer after the medium-voltage switch 89T-C4 is connected in series. The connection node between the switch 89T-C4 and the medium-voltage C-phase bushing of the transformer is connected to the ground after the surge arrester is connected in series. The medium-voltage C-phase system of the substation is connected to the medium-voltage bypass bus after the medium-voltage switch 89T-C5 is connected in series. The low-voltage C-phase bushing of the transformer is connected to the B phase of the low-voltage bypass bus through a jumper. The low-voltage C-phase bushing of the transformer is connected to the C phase of the low-voltage bypass bus through a jumper. The neutral point of the C phase of the transformer is connected to the neutral point bus through a jumper connected in series. The neutral point bus is connected to the ground after the single-phase CT is connected in series.

[0044] When disconnectors 89T-C2, 89T-C3 and medium-voltage disconnector 89T-C5 are all closed, it indicates that the C phase of the transformer is out of service.

[0045] When disconnectors 89T-C2, 89T-C3, and medium-voltage disconnector 89T-C5 are all disconnected, it indicates that the C phase of the transformer is in operation.

[0046] Furthermore, in this embodiment, the high-voltage side bypass switch of the main transformer includes switch 89T-B2 and switch 89T-B3. The high-voltage B-phase system of the substation is connected in series with switch 89T-B2 and switch 89T-B3 and then electrically connected to the high-voltage bypass bus.

[0047] The main transformer high-voltage side disconnector includes disconnector 89T-B1. The high-voltage B-phase system of the substation is connected in series with disconnector 89T-B1 and then connected to the high-voltage B-phase bushing of the transformer. The high-voltage B-phase bushing of the transformer is connected in series with a surge arrester and then grounded. Disconnector 89T-B1 is connected in series with a grounding switch and then grounded.

[0048] The medium-voltage side bypass switch of the main transformer includes medium-voltage switch 89T-B4 and medium-voltage switch 89T-B5. The medium-voltage B-phase system of the substation is connected to the medium-voltage side B-phase bushing of the transformer after the medium-voltage switch 89T-B4 is connected in series. The connection node between switch 89T-B4 and the medium-voltage side B-phase bushing of the transformer is connected to the ground after the surge arrester is connected in series. The medium-voltage B-phase system of the substation is connected to the medium-voltage bypass bus after the medium-voltage switch 89T-B5 is connected in series. The low-voltage side B-phase bushing of the transformer is connected to the B phase of the low-voltage bypass bus through a jumper. The low-voltage side B-phase bushing of the transformer is connected to the B phase of the low-voltage bypass bus through a jumper. The neutral point of the B phase of the transformer is connected to the neutral point bus through a jumper connected in series. The neutral point bus is connected to the ground after the single-phase CT is connected in series.

[0049] When disconnectors 89T-B2, 89T-B3 and medium-voltage disconnector 89T-B5 are all closed, it indicates that phase B of the transformer is out of service.

[0050] When disconnectors 89T-B2, 89T-B3, and medium-voltage disconnector 89T-B5 are all disconnected, it indicates that phase B of the transformer is in operation.

[0051] Furthermore, in this embodiment, the high-voltage side bypass switch of the main transformer includes switch 89T-A2 and switch 89T-A3. The high-voltage A-phase system of the substation is connected in series with switch 89T-A2 and switch 89T-A3 and then electrically connected to the high-voltage bypass bus.

[0052] The main transformer high-voltage side disconnector includes disconnector 89T-A1. The high-voltage A-phase system of the substation is connected in series with disconnector 89T-A1 and then connected to the high-voltage A-phase bushing of the transformer. The high-voltage A-phase bushing of the transformer is connected in series with a surge arrester and then grounded. Disconnector 89T-A1 is connected in series with a grounding switch and then grounded.

[0053] The medium-voltage side bypass switch of the main transformer includes medium-voltage switch 89T-A4 and medium-voltage switch 89T-A5. The medium-voltage A-phase system of the substation is connected to the medium-voltage A-phase bushing of the transformer after the medium-voltage switch 89T-A4 is connected in series. The connection node between the switch 89T-A4 and the medium-voltage A-phase bushing of the transformer is connected to the ground after the surge arrester is connected in series. The medium-voltage A-phase system of the substation is connected to the medium-voltage bypass bus after the medium-voltage switch 89T-A5 is connected in series. The low-voltage A-phase bushing of the transformer is connected to the B phase of the low-voltage bypass bus through a jumper. The low-voltage A-phase bushing of the transformer is connected to the A phase of the low-voltage bypass bus through a jumper. The neutral point of the A phase of the transformer is connected to the neutral point bus through a jumper. The neutral point bus is connected to the ground after the single-phase CT is connected in series.

[0054] When disconnectors 89T-A2, 89T-A3, and medium-voltage disconnector 89T-A5 are all closed, it indicates that phase A of the transformer is out of service.

[0055] When disconnectors 89T-A2, 89T-A3, and medium-voltage disconnector 89T-A5 are all disconnected, it indicates that phase A of the transformer is in operation.

[0056] Furthermore, in this embodiment, the standby phase high-voltage side bushing is electrically connected to the high-voltage bypass bus, the standby phase low-voltage side bushing is electrically connected to phase A of the low-voltage bypass bus via a jumper, the standby phase low-voltage side bushing is electrically connected to phase B of the low-voltage bypass bus via a jumper, the standby phase medium-voltage side bushing is electrically connected to the medium-voltage bypass bus, the standby phase high-voltage side bushing is electrically connected to the surge arrester and then grounded, the standby phase medium-voltage side bushing is electrically connected to the surge arrester and then grounded, the standby phase neutral point is connected to the neutral point bus via a jumper, and the neutral point bus is connected to the single-phase CT in series and then grounded.

[0057] If at least one of the three conditions—transformer A phase decommissioning, transformer B phase decommissioning, and transformer C phase decommissioning—is met, the standby phase will be activated and put into operation.

[0058] If all three conditions for transformer A phase to operate, transformer B phase to operate, and transformer C phase to operate are met, then the standby phase will be taken out of operation.

[0059] Furthermore, in this embodiment, the control protection circuit of the relay protection includes the normally closed contact 75XA of the transformer A phase switching relay, transformer A phase non-electrical quantity 1, transformer A phase non-electrical quantity 2, the first coil of the 130A relay, and the second coil of the 130A relay. The positive signal power supply is connected in series with the normally closed contact 75XA of the transformer A phase switching relay, transformer A phase non-electrical quantity 1, and the first coil of the 130A relay, and then electrically connected to the negative signal power supply. The transformer A phase non-electrical quantity 2 is connected in series with the second coil of the 130A relay and then connected in parallel with the transformer A phase non-electrical quantity 1 and the first coil of the 130A relay.

[0060] The first set of coils of the 130A relay includes resistor RA1, resistor RA3, diode LA1, and coils JA1, JA2, and JA3 of the transformer A-phase switching relay. Resistors RA1, JA1, JA2, and JA3 are connected in series and then electrically connected to the negative power supply of the signal. Resistor RA3 is connected in series with diode LA1 and then connected in parallel with resistors RA1, JA1, JA2, and JA3 of the transformer A-phase switching relay. Resistor RA1 is electrically connected to the non-electrical quantity 1 of the transformer A phase.

[0061] The second set of coils for the 130A relay includes resistor RA2, resistor RA4, diode LA2, and coils JA5, JA6, and JA7 of the transformer A-phase switching relay. Resistors RA2, JA5, JA6, and JA7 are connected in series and then electrically connected to the negative power supply. Resistor RA4 is connected in series with diode LA1 and then in parallel with resistors RA2, JA5, JA6, and JA7. Resistor RA2 in the second set of coils of the 130A relay is electrically connected to the non-electrical quantity 2 of the transformer A phase.

[0062] The control and protection circuit of the relay protection also includes the normally closed contact 75XB of the transformer B phase switching relay, transformer B phase non-electrical quantity 1, transformer B phase non-electrical quantity 2, the first coil of the 130B relay and the second coil of the 130B relay. The signal positive power supply is connected in series with the normally closed contact 75XB of the transformer B phase switching relay, transformer B phase non-electrical quantity 1 and the first coil of the 130B relay and then electrically connected to the signal negative power supply. The transformer B phase non-electrical quantity 2 is connected in series with the second coil of the 130B relay and then connected in parallel with the transformer B phase non-electrical quantity 1 and the first coil of the 130B relay.

[0063] The first set of coils of the 130B relay includes resistor RB1, resistor RB3, diode LB1, coils JB1, JB2, and JB3 of the transformer B phase switching relay. Resistors RB1, JB2, and JB3 are connected in series and then electrically connected to the negative power supply of the signal. Resistor RB3 is connected in series with diode LB1 and then connected in parallel with resistors RB1, JB2, and JB3 of the transformer B phase switching relay. Resistor RB1 is electrically connected to the non-electrical quantity 1 of the transformer B phase.

[0064] The second set of coils of the 130B relay includes resistor RB2, resistor RB4, diode LB2, and coils JB5, JB6, and JB7 of the transformer B-phase switching relay. Resistors RB2, JB5, JB6, and JB7 are connected in series and then electrically connected to the negative power supply. Resistor RB4 is connected in series with diode LB1 and then in parallel with resistors RB2, JB5, JB6, and JB7. Resistor RB2 in the second set of coils of the 130B relay is electrically connected to the non-electrical quantity 2 of the transformer B phase.

[0065] The control and protection circuit of the relay protection also includes the normally closed contact 75XC of the transformer C-phase switching relay, transformer C-phase non-electrical quantity 1, transformer C-phase non-electrical quantity 2, the first coil of the 130C relay and the second coil of the 130C relay. The signal positive power supply is connected in series with the normally closed contact 75XC of the transformer C-phase switching relay, transformer C-phase non-electrical quantity 1 and the first coil of the 130C relay and then electrically connected to the signal negative power supply. The transformer C-phase non-electrical quantity 2 is connected in series with the second coil of the 130C relay and then connected in parallel with the transformer C-phase non-electrical quantity 1 and the first coil of the 130C relay.

[0066] The first set of coils of the 130C relay includes resistor RC1, resistor RC3, diode LC1, coils JC1, JC2, and JC3 of the transformer C-phase switching relay. Resistors RC1, JC2, and JC3 are connected in series and then electrically connected to the negative power supply of the signal. Resistor RC3 is connected in series with diode LC1 and then connected in parallel with resistors RC1, JC1, JC2, and JC3 of the transformer C-phase switching relay. Resistor RC1 is electrically connected to the non-electrical quantity 1 of the transformer C phase.

[0067] The second set of coils in the 130C relay includes resistor RC2, resistor RC4, diode LC2, and coils JC5, JC6, and JC7 of the transformer C-phase switching relay. These coils are connected in series and then electrically connected to the negative power supply. Resistor RC4 is connected in series with diode LC1 and then in parallel with resistors RC2, JC5, JC6, and JC7. Resistor RC2 in the second set of coils of the 130C relay is electrically connected to the non-electrical quantity 2 of the transformer C-phase.

[0068] The control and protection circuit of the relay protection also includes the normally open contact 75X of the standby phase switching relay, standby phase non-electrical quantity 1, standby phase non-electrical quantity 2, the first coil of the 130S relay and the second coil of the 130S relay. The signal positive power supply is connected in series with the normally closed contact 75X of the standby phase switching relay, standby phase non-electrical quantity 1 and the first coil of the 130S relay and then electrically connected to the signal negative power supply. The standby phase non-electrical quantity 2 is connected in series with the second coil of the 130S relay and then connected in parallel with the standby phase non-electrical quantity 1 and the first coil of the 130S relay.

[0069] The first set of coils of the 130S relay includes resistor RS1, resistor RS3, diode LS1, and coils JS1, JS2, and JS3 of the transformer S-phase switching relay. Resistors RS1, JS1, JS2, and JS3 are connected in series and then electrically connected to the negative power supply of the signal. Resistor RS3 is connected in series with diode LS1 and then connected in parallel with resistors RS1, JS1, JS2, and JS3 of the transformer S-phase switching relay. Resistor RS1 is electrically connected to the non-electrical quantity 1 of the transformer S-phase.

[0070] The second set of coils of the 130S relay includes resistor RS2, resistor RS4, diode LS2, and coils JS5, JS6, and JS7 of the transformer S-phase switching relay. Resistors RS2, JS5, JS6, and JS7 are connected in series and then electrically connected to the negative power supply of the signal. Resistor RS4 is connected in series with diode LS1 and then connected in parallel with resistors RS2, JS5, JS6, and JS7 of the transformer S-phase switching relay. Resistor RS2 in the second set of coils of the 130S relay is electrically connected to the non-electrical quantity 2 of the transformer S-phase.

[0071] Furthermore, in this embodiment, non-electrical quantity 1 and non-electrical quantity 2 are two of the following: high oil temperature, high winding temperature, and gas pressure release trip. Switching refers to switching the non-electrical quantity and zero differential protection signals through a relay.

[0072] Furthermore, in this embodiment, the transformer A-phase switching relay, transformer B-phase switching relay, transformer C-phase switching relay, and spare phase switching relay are dual-position magnetic latching relays.

[0073] Figure 1 As shown, the electrical primary three-wire diagram of the substation phase transformer and standby phase is shown. The electrical primary switching is carried out by switching operation through high voltage / medium voltage disconnect switch. After the corresponding phase isolation is completed, the remaining points are connected with flexible wire jumpers.

[0074] Figure 2As shown, the switching circuit of the electrical secondary system uses measurement and control devices and relays based on the operation sequence of the electrical primary system. The operating condition of the normal phase of the main transformer is determined by the position of the disconnect switch. The normal phase of the main transformer is considered to be in the off state only when all the bypass disconnect switches on the high and medium voltage sides are connected to the corresponding bypass busbars. The normal phase of the main transformer is considered to be in the on state only when all the bypass disconnect switches on the high and low voltage sides are open. The standby phase, since there is no electrically controlled disconnect switch, is determined by inferring its state from the operating condition of the normal phase of the main transformer. That is, when any phase of the normal phase of the main transformer is officially off, the standby phase is considered to be in the on state. The standby phase is considered to be off state only when all three phases of the normal phase of the main transformer are in the on state.

[0075] Figure 3 As shown, the standby phase zero-differential protection adopts high-impedance zero-differential protection, and the CTs on each side are connected in parallel. When the standby phase is in the off state, the CT is shorted by switching relay 75X to avoid the CT being open-circuited; when the standby phase is in the on state, the current is sent to the zero-differential protection by switching relay 75X to realize the protection function.

[0076] Figure 4 As shown, the switching of non-electrical quantity signals, taking the A-phase bypass as an example, when the A-phase is deactivated, the input of the relevant non-electrical quantity signals of the A-phase is cut off through the 75XA relay contact. At this time, the standby phase is put into operation. After the relevant non-electrical quantity signals are activated through the 75X relay, they are sent to the protection system to realize the reliable deactivation of the deactivated phase and the normal operation of the put-in phase.

[0077] By switching the above circuits, the electrical secondary circuits can be automatically switched after the backup phase is switched, without the need for manual operation. This improves construction efficiency and avoids wiring errors caused by manual rewiring, which could lead to on-site accidents.

[0078] The high-voltage A-phase system, high-voltage B-phase system, high-voltage C-phase system, medium-voltage A-phase system, medium-voltage B-phase system, medium-voltage C-phase system, normal phase of main transformer, standby phase, and dual-position magnetic latching relay of the substation are all available in many models in the prior art. Those skilled in the art can select the appropriate model according to actual needs. This embodiment will not provide examples of each model. Zero differential protection signal is also a prior art technology and will not be explained in detail in this embodiment.

[0079] In this invention, the jumper is an interface that relies on automated robotic arms / human labor to complete the jumper connection.

[0080] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A substation transformer backup phase automatic switching circuit, characterized by, The main transformer normal phase related primary equipment signal is collected, the main transformer normal phase includes transformer A phase, transformer B phase and transformer C phase, whether the standby phase is put into is judged based on the three-phase state of the main transformer normal phase, when the standby phase is put into, the non-electric quantity control switch signal of the standby phase and the current signal of the standby phase are switched to the control protection circuit of the relay protection; The main transformer normal phase related primary equipment signal includes the position state of the main transformer high voltage side switch group, the position state of the main transformer high voltage side bypass switch group and the position state of the main transformer medium voltage side switch group; The condition of judging whether the standby phase is put into includes: when the main transformer high voltage side bypass switch group and the main transformer medium voltage side switch group of the main transformer normal phase are both closed, it indicates that the corresponding phase of the main transformer normal phase exits, and the standby phase is in the state of being put into; only when the main transformer high voltage side bypass switch group and the main transformer medium voltage side switch group are both opened, and the three phases of the main transformer normal phase are all in the state of being put into work, the standby phase exits; The main transformer high voltage side bypass switch group includes switch 89T-C2 and switch 89T-C3, and the high voltage bypass bus is electrically connected after the switch 89T-C2 and the switch 89T-C3 are connected in series in the high voltage C phase system of the substation; The main transformer high voltage side switch group includes switch 89T-C1, and the transformer high voltage side C phase bushing is connected after the switch 89T-C1 is connected in series in the high voltage C phase system of the substation; The main transformer medium voltage side switch group includes medium voltage switch 89T-C4 and medium voltage switch 89T-C5, the transformer medium voltage side C phase bushing is connected after the medium voltage switch 89T-C4 is connected in series in the medium voltage C phase system of the substation, the medium voltage bypass bus is electrically connected after the medium voltage switch 89T-C5 is connected in series in the medium voltage C phase system of the substation, the transformer low voltage side C phase bushing is connected to the B phase of the low voltage bypass bus through a jumper, the transformer low voltage side C phase bushing is connected to the C phase of the low voltage bypass bus through a jumper, the transformer C phase neutral point is connected to the neutral point bus after being connected in series with a jumper, and the neutral point bus is grounded after being connected in series with a single-phase CT; When the switch 89T-C2, the switch 89T-C3 and the medium voltage switch 89T-C5 are all closed, it indicates that the transformer C phase exits work; When the switch 89T-C2, the switch 89T-C3 and the medium voltage switch 89T-C5 are all opened, it indicates that the transformer C phase is put into work; The main transformer high voltage side bypass switch group includes switch 89T-B2 and switch 89T-B3, and the high voltage bypass bus is electrically connected after the switch 89T-B2 and the switch 89T-B3 are connected in series in the high voltage B phase system of the substation; The main transformer high voltage side switch group includes switch 89T-B1, and the transformer high voltage side B phase bushing is connected after the switch 89T-B1 is connected in series in the high voltage B phase system of the substation; The main transformer medium voltage side switch group includes medium voltage switch 89T-B4 and medium voltage switch 89T-B5, the substation medium voltage B phase system is connected to the transformer medium voltage side B phase bushing after the series connection of the medium voltage switch 89T-B4, the substation medium voltage B phase system is connected to the medium voltage bypass bus after the series connection of the medium voltage switch 89T-B5, the transformer low voltage side B phase bushing is connected to the A phase of the low voltage bypass bus through a jumper, the transformer low voltage side B phase bushing is connected to the B phase of the low voltage bypass bus through a jumper, the transformer B phase neutral point is connected to the neutral point bus through a jumper after the series connection of the jumper, and the neutral point bus is grounded after the series connection of a single-phase CT; When the switch 89T-B2, the switch 89T-B3 and the medium voltage switch 89T-B5 are all closed, it indicates that the transformer B phase is out of work; When the switch 89T-B2, the switch 89T-B3 and the medium voltage switch 89T-B5 are all disconnected, it indicates that the transformer B phase is put into work; The main transformer high voltage side bypass switch group includes the switch 89T-A2 and the switch 89T-A3, and the substation high voltage A phase system is connected to the high voltage bypass bus after the series connection of the switch 89T-A2 and the switch 89T-A3; The main transformer high voltage side switch group includes the switch 89T-A1, and the substation high voltage A phase system is connected to the transformer high voltage side A phase bushing after the series connection of the switch 89T-A1; The main transformer medium voltage side switch group includes medium voltage switch 89T-A4 and medium voltage switch 89T-A5, the substation medium voltage A phase system is connected to the transformer medium voltage side A phase bushing after the series connection of the medium voltage switch 89T-A4, the substation medium voltage A phase system is connected to the medium voltage bypass bus after the series connection of the medium voltage switch 89T-A5, the transformer low voltage side A phase bushing is connected to the A phase of the low voltage bypass bus through a jumper, the transformer low voltage side A phase bushing is connected to the C phase of the low voltage bypass bus through a jumper, the transformer A phase neutral point is connected to the neutral point bus through a jumper, and the neutral point bus is grounded after the series connection of a single-phase CT; When the switch 89T-A2, the switch 89T-A3 and the medium voltage switch 89T-A5 are all closed, it indicates that the transformer A phase is out of work; When the switch 89T-A2, the switch 89T-A3 and the medium voltage switch 89T-A5 are all disconnected, it indicates that the transformer A phase is put into work.

2. A substation transformer backup phase automatic switching circuit according to claim 1, characterized in that, The standby phase high voltage side bushing is connected to the high voltage bypass bus, the standby phase low voltage side bushing is connected to the A phase of the low voltage bypass bus through a jumper, the standby phase low voltage side bushing is connected to the B phase of the low voltage bypass bus through a jumper, the standby phase medium voltage side bushing is connected to the medium voltage bypass bus, the standby phase neutral point is connected to the neutral point bus through a jumper, and the neutral point bus is grounded after the series connection of a single-phase CT; At least one of the transformer A phase out of work, the transformer B phase out of work and the transformer C phase out of work is satisfied, and the standby phase is put into work; All of the transformer A phase in work, the transformer B phase in work and the transformer C phase in work are satisfied, and the standby phase is out of work.

3. The substation transformer standby phase automatic switching circuit according to claim 1, wherein The control protection circuit of the relay protection comprises a normally closed contact 75XA of a transformer A-phase switching relay, a transformer A-phase non-electric quantity control switch 1, a transformer A-phase non-electric quantity control switch 2, a first group of coils of a 130A relay and a second group of coils of the 130A relay, the signal positive power source is connected to the signal negative power source in series with the normally closed contact 75XA of the transformer A-phase switching relay, the transformer A-phase non-electric quantity control switch 1 and the first group of coils of the 130A relay, and the transformer A-phase non-electric quantity control switch 2 is connected in parallel on the transformer A-phase non-electric quantity control switch 1 and the first group of coils of the 130A relay in series with the second group of coils of the 130A relay; The control protection circuit of the relay protection further comprises a normally closed contact 75XB of a transformer B-phase switching relay, a transformer B-phase non-electric quantity control switch 1, a transformer B-phase non-electric quantity control switch 2, a first group of coils of a 130B relay and a second group of coils of the 130B relay, the signal positive power source is connected to the signal negative power source in series with the normally closed contact 75XB of the transformer B-phase switching relay, the transformer B-phase non-electric quantity control switch 1 and the first group of coils of the 130B relay, and the transformer B-phase non-electric quantity control switch 2 is connected in parallel on the transformer B-phase non-electric quantity control switch 1 and the first group of coils of the 130B relay in series with the second group of coils of the 130B relay; The control protection circuit of the relay protection further comprises a normally closed contact 75XC of a transformer C-phase switching relay, a transformer C-phase non-electric quantity control switch 1, a transformer C-phase non-electric quantity control switch 2, a first group of coils of a 130C relay and a second group of coils of the 130C relay, the signal positive power source is connected to the signal negative power source in series with the normally closed contact 75XC of the transformer C-phase switching relay, the transformer C-phase non-electric quantity control switch 1 and the first group of coils of the 130C relay, and the transformer C-phase non-electric quantity control switch 2 is connected in parallel on the transformer C-phase non-electric quantity control switch 1 and the first group of coils of the 130C relay in series with the second group of coils of the 130C relay; The control protection circuit of the relay protection further comprises a normally closed contact 75X of a standby phase switching relay, a standby phase non-electric quantity control switch 1, a standby phase non-electric quantity control switch 2, a first group of coils of a 130S relay and a second group of coils of the 130S relay, the signal positive power source is connected to the signal negative power source in series with the normally closed contact 75X of the standby phase switching relay, the standby phase non-electric quantity control switch 1 and the first group of coils of the 130S relay, and the standby phase non-electric quantity control switch 2 is connected in parallel on the standby phase non-electric quantity control switch 1 and the first group of coils of the 130S relay in series with the second group of coils of the 130S relay.

4. The substation transformer standby phase automatic switching circuit according to claim 3, wherein The transformer A-phase switching relay, the transformer B-phase switching relay, the transformer C-phase switching relay and the standby phase switching relay are double-position magnetic latching relays.

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