A two-incoming line and one busbar seamless switching overload protection system

Abstract

The utility model discloses an overload protection system before seamless switching of two incoming lines and one bus tie, comprising an intermediate relay, a voltage relay, a PLC programmable logic controller and an incoming line power transmitter, wherein the PLC programmable logic controller is electrically connected to a first incoming line frame circuit breaker, a second incoming line frame circuit breaker, a bus tie frame circuit breaker, the incoming line power transmitter and the intermediate relay, and the first incoming line current transformer, the second incoming line current transformer and the voltage relay are all electrically connected to the incoming line power transmitter. The utility model receives each switch state, power supply condition, and the total amount of load transmission current through the PLC programmable logic controller to judge whether it meets the requirement of seamless switching and not overloading before allowing switching, and can efficiently and conveniently realize overload judgment before switching.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical power distribution frames, in particular to an overload protection system before seamless switching of two incoming lines and one busbar. Background Art

[0002] In the power system, seamless switching of two incoming lines and one busbar is a common configuration, which aims to ensure that when one power line fails, the system can quickly and smoothly switch to the backup power supply to maintain continuous power supply to the system.

[0003] Until now, the seamless switching of two incoming lines and one busbar has not judged whether the system will be overloaded after the switching. If the overload is judged after the switching, the following situations will occur:

[0004] (1) If no overload is detected after switching, the system operates normally.

[0005] (2) If an overload is detected after switching, the incoming line switch will be forced to trip due to overload, resulting in significant economic losses. Utility Model Content

[0006] In order to overcome the above technical defects, the utility model provides an overload protection system before seamless switching of two incoming lines and one busbar, which can realize overload judgment before switching.

[0007] In order to solve the above problems, the utility model is implemented according to the following technical solutions:

[0008] The utility model provides an overload protection system before seamless switching of two incoming lines and one bus tie, comprising an intermediate relay, a voltage relay, a PLC programmable logic controller and an incoming line power transmitter, wherein the PLC programmable logic controller is electrically connected to a first incoming line frame circuit breaker, a second incoming line frame circuit breaker, a bus tie frame circuit breaker, the incoming line power transmitter and the intermediate relay, and the first incoming line current transformer, the second incoming line current transformer and the voltage relay are all electrically connected to the incoming line power transmitter.

[0009] As an improvement of the above scheme, the switch opening and closing state contacts, switch exit position contacts, switch ready-to-close contacts and switch fault state contacts of the first incoming frame circuit breaker, the second incoming frame circuit breaker and the main coupling frame circuit breaker are all electrically connected to the PLC programmable logic controller.

[0010] As an improvement of the above solution, the PLC programmable logic controller is connected to the A-phase, B-phase and C-phase contacts of the voltage relay.

[0011] As an improvement of the above scheme, it also includes a conversion switch, and the automatic column separation contacts, manual column separation contacts, stop contacts and manual parallel contacts of the conversion switch are all electrically connected to the PLC programmable logic controller.

[0012] As an improvement of the above solution, it also includes a fuse, which is electrically connected to the PLC programmable logic controller.

[0013] As an improvement of the above scheme, the incoming line power transmitter includes a first incoming line power transmitter and a second incoming line power transmitter, the first incoming line current transformer is connected to the sampling side of the first incoming line power transmitter, and the second incoming line current transformer is connected to the sampling side of the second incoming line power transmitter.

[0014] As an improvement of the above solution, the voltage relay includes a first voltage relay and a second voltage relay, the first voltage relay is connected to the sampling side of the first incoming power transmitter, and the second voltage relay is connected to the sampling side of the second incoming power transmitter.

[0015] As an improvement of the above solution, it also includes an indicator light, which is electrically connected to the PLC programmable logic controller.

[0016] As an improvement of the above scheme, the indicator lights include a PLC operation indicator light, a manual parallel indicator light, a manual separate indicator light, an automatic separate indicator light and a total power overload indicator light.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] The present application calculates the output of the incoming power transmitter through a PLC programmable logic controller, and determines whether the output is less than the set value of the transformer full load. If so, switching is allowed; if so, switching is prohibited. It can efficiently and conveniently realize overload judgment before switching, and is easy to install, simple to maintain, and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The specific implementation of the utility model is further described in detail below with reference to the accompanying drawings, wherein:

[0020] Figure 1 Part of the principle of the overload protection system before seamless switching of two incoming lines and one bus tie in the embodiment of the utility model Figure 1 ;

[0021] Figure 2 Part of the principle of the overload protection system before seamless switching of two incoming lines and one bus tie in the embodiment of the utility model Figure 2 ;

[0022] Figure 3Part of the principle of the overload protection system before seamless switching of two incoming lines and one bus tie in the embodiment of the utility model Figure 3 .

[0023] Description of reference numerals:

[0024] 1. 1# incoming frame circuit breaker status signal (QF1);

[0025] 2. 2# incoming frame circuit breaker status signal (QF2);

[0026] 3. 1KVA, B, C voltage relay (mains 1 power supply signal);

[0027] 4. 2KVA, B, C voltage relay (mains 2 power supply signal);

[0028] 5. Bus tie frame circuit breaker status signal (QF3);

[0029] 6. SA mode selection switch;

[0030] 7. 1T1~3 1# incoming current transformer;

[0031] 8. 1BD 1# incoming power transmitter (first incoming power transmitter);

[0032] 9. 2T1~3 2# incoming current transformer;

[0033] 10. 2BD 2# incoming power transmitter (second incoming power transmitter);

[0034] 11. K1~7 intermediate relay;

[0035] 12. HB1~3, HR2, HG0 indicator lights;

[0036] 13.PLC programmable logic controller;

[0037] 14. FUPLC1~2 fuses. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0039] Example 1

[0040] In the existing seamless switching of two incoming lines and one bus tie, the 1# incoming line frame circuit breaker only supplies the load of this section; the 2# incoming line frame circuit breaker only supplies the load of this section; the bus tie frame circuit breaker is in the disconnected state; but in the seamless switching, the bus tie frame circuit breaker is closed first to make the line in parallel state, and then the 1# incoming line frame circuit breaker or the 2# incoming line frame circuit breaker is opened. The load does not stop power during the switching process. The existing two incoming lines and one bus tie system does not judge whether the system will be overloaded after the switching. The overload is judged after the switching. If the overload is detected after the switching, it will cause the incoming line switch to trip due to forced overload, which will cause significant economic losses.

[0041] This embodiment provides an overload protection system for seamless switching between two incoming lines and one busbar, including a fuse, a transfer switch, an intermediate relay, a voltage relay, an indicator light, a PLC programmable logic controller, and an incoming line power transmitter. Figures 1 to 3 As shown, the PLC programmable logic controller is electrically connected to the 1# incoming frame circuit breaker, the 2# incoming frame circuit breaker, the busbar frame circuit breaker, the incoming power transmitter, the intermediate relay, the transfer switch, the fuse, the voltage relay and the indicator light, and the 1# incoming current transformer, the 2# incoming current transformer and the voltage relay are all electrically connected to the incoming power transmitter.

[0042] It should be noted that the 1# incoming line frame includes the 1# incoming line frame circuit breaker, the 1# incoming line current transformer and its control circuit, the 2# incoming line frame includes the 2# incoming line frame circuit breaker, the 2# incoming line current transformer and its control circuit, and the bus tie frame includes the bus tie frame circuit breaker and its control circuit. The content here can refer to the prior art.

[0043] Specifically, in this embodiment, continue to refer to Figures 1 to 3 The fuse, PLC programmable logic controller, transfer switch, intermediate relay, and indicator light form a control loop, and the PLC programmable logic controller receives the status signal of 1# incoming frame circuit breaker, the status signal of 2# incoming frame circuit breaker, the mains 1 power supply signal, the mains 2 power supply signal, the busbar frame circuit breaker status signal, the SA transfer switch signal, the first incoming power transmission signal, and the second incoming power transmission signal. The PLC programmable logic controller calculates and determines whether the sum of the 2 power transmissions is less than the set value of the transformer full load. If so, switching is allowed, and if so, switching is prohibited.

[0044] Specifically, the PLC programmable logic controller is electrically connected to the switch opening and closing status contacts, switch exit position contacts, switch ready-to-close contacts and switch fault status contacts of the 1# incoming frame circuit breaker; the PLC programmable logic controller is electrically connected to the switch opening and closing status contacts, switch exit position contacts, switch ready-to-close contacts and switch fault status contacts of the 2# incoming frame circuit breaker; the PLC programmable logic controller is electrically connected to the switch opening and closing status contacts, switch exit position contacts, switch ready-to-close contacts and switch fault status contacts of the main coupling frame circuit breaker.

[0045] Specifically, the automatic sorting contacts, manual sorting contacts, stop contacts and manual parallel contacts of the conversion switch are all electrically connected to the PLC programmable logic controller to realize the automatic sorting, manual sorting, stop and manual paralleling functions of the system.

[0046] In this embodiment, a power monitoring module is composed of 1KVA, B, C voltage relay, 2KVA, B, C voltage relay, 1T1~3 1# incoming line current transformer, 2T1~3 2# incoming line current transformer, 1BD 1# incoming line power transmitter, and 2BD 2# incoming line power transmitter, which is used to detect the power supply status.

[0047] Specifically, the 1KVA, B, C voltage relay is used to detect whether the mains 1 has power, and the 2KVA, B, C voltage relay is used to detect whether the mains 2 has power, and the signal is input to the PLC programmable logic controller for calculation; the 1T1~3 1# incoming line current transformer is used to detect the current signal of the mains 1, and the signal is input to the 1BD 1# incoming line power transmitter, and then the power transmitter outputs the power transmission signal to the PLC programmable logic controller for calculation;

[0048] The logic operation control module of the protection system is composed of SA mode selection switch, K1~7 intermediate relays, HB1~3, HR2, HG0 indicator lights, PLC programmable logic controller, and FUPLC1~2 fuses, which are used for logic operation and output indication and control signals.

[0049] Specifically, (1) the control mode is selected through the SA mode selection switch, and the signal is input into the PLC programmable logic controller for calculation; (2) the auxiliary contact status signal of the circuit breaker in the switching module is input into the PLC programmable logic controller for calculation; (3) the PLC programmable logic controller receives the required signals (signals indicating whether the mains 1 and 2 are powered, 1~2BD power transmission signals, control mode signals, circuit breaker status signals), and after logical calculation, outputs status indication signals (such as: PLC operation, manual parallel, manual split, automatic split (automatic transfer but not automatic recovery), total power overload of incoming line 1 + incoming line 2) through the HB1~3, HR2, HG0 indicator lights, and outputs circuit breaker control signals (such as 1#~2# incoming line frame circuit breaker closing command, 1#~2# incoming line frame circuit breaker opening command, bus tie frame circuit breaker closing command, bus tie frame circuit breaker opening command, total power overload prohibition closing command) through the K1~7 intermediate relays.

[0050] It should be noted that the switching module is composed of QF1 1# incoming frame circuit breaker, QF2 2# incoming frame circuit breaker, and QF3 bus tie frame circuit breaker. The control signal is output through the PLC programmable logic controller to control the closing and opening of the switches in the switching module to realize the switching of the AC power supply.

[0051] In this embodiment, the PLC programmable logic controller receives the status signal of the 1# incoming frame circuit breaker QF1, the status signal of the 2# incoming frame circuit breaker QF2, the mains 1 power supply signal, the mains 2 power supply signal, and the bus tie frame circuit breaker QF3 status signal, and receives the action signal of the SA conversion switch, receives the 1BD and 2BD power transmission signals, when the SA conversion switch is in the manual parallel state and meets the manual seamless switching requirements (mains 1 and mains 2 are active and synchronous, the 1# incoming frame circuit breaker QF1 and the 2# incoming frame circuit breaker QF2 are in the closed state, and the bus tie frame circuit breaker QF3 is in the open state). When the voltage is greater than the set value, a signal is sent to prohibit switching, and switching is prohibited through the electrical control circuit of the circuit breaker itself (closing the busbar frame circuit breaker QF3, and then opening the 1# incoming frame circuit breaker QF1 or the 2# incoming frame circuit breaker QF2); if it is greater than the set value, a signal is sent to prohibit switching, and switching is prohibited through the electrical control circuit of the circuit breaker itself (closing the busbar frame circuit breaker QF3 is prohibited), which can efficiently and conveniently realize overload judgment before switching.

[0052] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A two-incoming line and one busbar seamless switching overload protection system, characterized in that: It includes an intermediate relay, a voltage relay, a PLC programmable logic controller and an incoming power transmitter. The PLC programmable logic controller is electrically connected to a first incoming frame circuit breaker, a second incoming frame circuit breaker, a busbar frame circuit breaker, the incoming power transmitter and the intermediate relay. The first incoming current transformer, the second incoming current transformer and the voltage relay are all electrically connected to the incoming power transmitter.

2. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 1 is characterized in that: The switch opening and closing state contacts, switch exit position contacts, switch ready-to-close contacts and switch fault state contacts of the first incoming frame circuit breaker, the second incoming frame circuit breaker and the bus tie frame circuit breaker are all electrically connected to the PLC programmable logic controller.

3. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 1 is characterized in that: The PLC programmable logic controller is connected to the A-phase, B-phase and C-phase contacts of the voltage relay.

4. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 1 is characterized in that: It also includes a conversion switch, and the automatic column separation contacts, manual column separation contacts, stop contacts and manual parallel contacts of the conversion switch are all electrically connected to the PLC programmable logic controller.

5. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 1 is characterized in that: It also includes a fuse, which is electrically connected to the PLC programmable logic controller.

6. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 1 is characterized in that: The incoming power transmitter comprises a first incoming power transmitter and a second incoming power transmitter, the first incoming current transformer is connected to a sampling side of the first incoming power transmitter, and the second incoming current transformer is connected to a sampling side of the second incoming power transmitter.

7. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 6 is characterized in that: The voltage relay includes a first voltage relay and a second voltage relay, wherein the first voltage relay is connected to a sampling side of the first incoming power transmitter, and the second voltage relay is connected to a sampling side of the second incoming power transmitter.

8. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 1 is characterized in that: It also includes an indicator light, which is electrically connected to the PLC programmable logic controller.

9. The overload protection system before seamless switching of two incoming lines and one bus tie according to claim 8 is characterized in that: The indicator lights include a PLC operation indicator light, a manual parallel indicator light, a manual separate indicator light, an automatic separate indicator light and a total power overload indicator light.

Images