Low penetration device for air pre-heater of thermal power plant

Abstract

The utility model discloses a low-pass device for an air pre-heater of a thermal power plant. The low-pass device comprises an incoming circuit breaker, a current limiting reactor, a power module, an SCR (Selective Catalytic Reduction) module, a load switch and a controller, the incoming circuit breaker, the current limiting reactor, the power module, the SCR module and the load switch are connected in sequence; the incoming circuit breaker is used for connecting an external power supply; the load switch is connected with the frequency converter; the controller is in communication connection with the power module and the silicon controlled module; according to the utility model, the plurality of power units connected in parallel are utilized to carry out direct current boost to improve the power output of the whole power module, so as to meet the requirements of a high-power air pre-heater frequency converter.

Description

Technical Field

[0001] The utility model relates to the technical field of low voltage ride through of frequency converter, and more specifically to a low voltage ride through device for air preheater of thermal power plant. Background Art

[0002] When the grid voltage drops temporarily, the inverter will be shut down for protection. The inverter shutdown of a thermal power plant will involve key production processes and safety, which will cause significant economic losses or cause major accidents. The low voltage ride-through device is a device used to solve this problem.

[0003] When the grid voltage is above 90% of the rated voltage, the low voltage ride-through device is in hot standby state, and the inverter is powered by the grid voltage; when the grid voltage drops instantly, within the range of 20%-90% of the rated voltage, the low voltage ride-through device (low voltage ride-through device) starts instantly to maintain the DC voltage of the inverter at 500V, ensuring that the inverter continues to operate normally without stopping, and the inverter is powered by the low voltage ride-through device; when the grid voltage returns to above 90% of the rated voltage, the low voltage ride-through device automatically exits and continues to be powered by the grid voltage. The traditional low voltage ride-through device is suitable for the application of small power inverters for coal feeders in thermal power plants. A single panel cabinet corresponds to a single small inverter, which is not suitable for the application of large power air preheaters in thermal power plants.

[0004] Therefore, how to improve the power of the low penetration device and expand its application in the air preheater of a thermal power plant is an urgent problem to be solved by technical personnel in this field. Utility Model Content

[0005] In view of this, the utility model provides a low penetration device for an air preheater of a thermal power plant, which utilizes multiple parallel power units to perform DC boost to increase the power output of the entire power module to meet the needs of a high-power air preheater inverter.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A low penetration device for an air preheater in a thermal power plant comprises an incoming line circuit breaker, a current limiting reactor, a power module, an SCR thyristor module, a load switch and a controller.

[0008] The incoming line circuit breaker, the current limiting reactor, the power module, the SCR thyristor module and the load switch are connected in sequence; the incoming line circuit breaker is used to connect an external power supply; and the load switch is used to connect a frequency converter.

[0009] The controller is communicatively connected with the power module and the thyristor module.

[0010] Preferably, the power module includes a plurality of power units connected in parallel; the power units are used to perform DC boost and output to the SCR thyristor module.

[0011] Preferably, the power unit includes a three-phase rectifier bridge and a step-up transformer; external alternating current is converted into direct current by the three-phase rectifier bridge, and the direct current is stepped up by the step-up transformer.

[0012] Preferably, the step-up transformer adopts a boost circuit.

[0013] Preferably, the power unit further includes a current Hall element and a first voltage collection board; the current Hall element is used to collect the DC current converted by the three-phase rectifier bridge and transmit the current value to the controller;

[0014] The voltage acquisition board is used to generate a conduction signal according to the voltage signal and the adjustment signal of the voltage sampling loop, and transmit the signal to the controller.

[0015] Preferably, it also includes a first fiber optic board and a second fiber optic board; the input end of the first fiber optic board is connected to the power module, and the output end is connected to the controller, so that the trigger signal is transmitted to the controller through the optical fiber; the input end of the second fiber optic board is connected to the controller, and the output end is connected to the power module, so that the control signal emitted by the controller is transmitted to the power module through the optical fiber.

[0016] Preferably, the second optical fiber board includes three sub-optical fiber boards for respectively controlling the three-phase triggering of the power module.

[0017] Preferably, the SCR thyristor module includes a thyristor, a diode module and a second voltage collection board.

[0018] The diode module includes a first diode and a second diode; the anode of the first diode is connected to the K pole of the thyristor, and the cathode is connected to the positive terminal of the inverter through the load switch; the anode of the second diode is connected to the negative terminal of the inverter, and the cathode is connected to the power module; the second voltage acquisition board respectively collects the A pole and K pole voltages of the thyristor, detects the conduction status of the thyristor, and outputs a conduction signal to the controller.

[0019] Preferably, a third optical fiber plate and a fourth optical fiber plate are also included.

[0020] The input end of the third optical fiber board is connected to the thyristor module, and the output end is connected to the controller, so that the trigger signal of the thyristor module is transmitted to the controller through optical fiber; the input end of the fourth optical fiber board is connected to the controller, and the output end is connected to the thyristor module, so that the control signal of the controller is transmitted to the thyristor module through optical fiber.

[0021] Preferably, the controller includes a voltage sampling module, a current sampling module and an optical fiber interface.

[0022] It can be seen from the above technical solution that, compared with the prior art, the utility model discloses a low-penetration device for an air preheater in a thermal power plant, which utilizes a plurality of parallel power units to perform DC boost to increase the power output of the entire power module to meet the needs of a high-power air preheater inverter; the power units are integrated into a power module for parallel output, which increases the power output while greatly improving the space utilization efficiency, and has a wider range of applications and more reliable stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 The utility model provides a schematic structural diagram of a low penetration device for an air preheater of a thermal power plant.

[0025] Figure 2 This invention provides a control circuit diagram of a low penetration device for an air preheater of a thermal power plant. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] The utility model embodiment discloses a low-breakdown device for an air preheater of a thermal power plant, comprising an incoming line circuit breaker, a current limiting reactor, a power module, an SCR thyristor module, a load switch and a controller; the incoming line circuit breaker, the current limiting reactor, the power module, the SCR thyristor module and the load switch are connected in sequence; the incoming line circuit breaker is used to connect an external power supply; the load switch is used to connect a frequency converter; and the controller is communicatively connected with the power module and the thyristor module.

[0028] Specific as Figure 1The incoming port of the incoming circuit breaker QF is connected to the external AC380V factory AC power supply by a cable; the outlet of the incoming circuit breaker QF is shunted by a copper busbar and connected to the incoming port of the power module PM with a wire, and the output end of the power module PM is connected to the positive and negative power supply terminals of the SCR thyristor module through a wire; the output terminal of the SCR thyristor module is connected to the incoming port of the load switch SW1 with a wire, and finally connected to the inverter of the air preheater of the thermal power plant.

[0029] In this embodiment, the power module includes two power units connected in parallel; the power unit is used to boost the DC voltage and output it to the SCR thyristor module; the power unit includes a three-phase rectifier bridge and a boost transformer; the external AC power is converted into DC power by the three-phase rectifier bridge, and the DC power is boosted by the boost transformer. The boost transformer adopts a boost circuit.

[0030] Furthermore, the power unit also includes a current Hall element and a first voltage acquisition board; the current Hall element is used to collect the DC current converted by the three-phase rectifier bridge, and transmit the current value to the controller; such as LA1, LA2 and LA11 in the figure; wherein LA1 and LA2 respectively collect the current output by the three-phase rectifier bridge in the corresponding power unit, and LA11 collects the output current and size of each three-phase rectifier bridge.

[0031] The voltage acquisition board is used to generate a conduction signal based on the voltage signal and adjustment signal of the voltage sampling circuit and transmit it to the controller. As shown in the figure, LV11 and LV12; LV11 and LV12 are used to collect the output voltage of the three-phase rectifier bridge.

[0032] In order to further implement the above technical solution, the power module and the controller communicate through optical fiber; specifically, it also includes a first optical fiber board and a second optical fiber board, the input end of the first optical fiber board is connected to the power module, and the output end is connected to the controller, so that the trigger signal is transmitted to the controller through the optical fiber; the input end of the second optical fiber board is connected to the controller, and the output end is connected to the power module, so that the control signal sent by the controller is transmitted to the power module through the optical fiber.

[0033] Furthermore, the second optical fiber board includes three sub-optical fiber boards, which are used to control the three-phase triggering of the power module respectively. Figure 2 As shown, one end of the fiber optic board KZB1, the fiber optic board KZB2 and the fiber optic board KZB3 are respectively connected to the JS2, JS4, and JS6 fiber optic interfaces, corresponding to the lower bridge triggering of the U phase, V phase and W phase in the power module; and the other ends of the above fiber optic boards are respectively connected to the TX2, TX4 and TX6 fiber optic interfaces of the controller.

[0034] In another embodiment, the SCR thyristor module includes a thyristor, a diode module and a second voltage acquisition board; the diode module includes a first diode and a second diode; the anode of the first diode is connected to the K pole of the thyristor, and the cathode overload switch is connected to the positive terminal of the inverter; the anode of the second diode is connected to the negative terminal of the inverter, and the cathode is connected to the power module; the second voltage acquisition board respectively collects the A pole and K pole voltages of the thyristor, detects the conduction status of the thyristor, and outputs the conduction signal to the controller.

[0035] In order to further implement the above technical solution, the SCR thyristor module and the controller communicate through optical fiber; specifically, it also includes a third optical fiber board and a fourth optical fiber board; the input end of the third optical fiber board is connected to the thyristor module, and the output end is connected to the controller, so that the trigger signal of the thyristor module is transmitted to the controller through the optical fiber; wherein the trigger signal of the thyristor is generated according to the A-level voltage and the K-pole voltage collected by the second voltage collection board.

[0036] The input end of the fourth optical fiber board is connected to the controller, and the output end is connected to the thyristor module, so that the control signal of the controller is transmitted to the thyristor module through the optical fiber.

[0037] Further, such as Figure 2 As shown, the optical fiber interface TX1 of the controller corresponds to the K and G pins of the thyristor SCR of the SCR thyristor module.

[0038] In another embodiment, the controller is connected to a voltage sampling loop, wherein the controller is used to generate a conduction signal based on a voltage signal and a modulation signal of the voltage sampling loop; the controller is also connected to a current sampling loop, wherein the controller is also used to generate a conduction signal based on a current signal and a modulation signal of the current sampling loop.

[0039] Specifically, the controller is connected to a push button switch, wherein the push button switch is used to generate an adjustment signal.

[0040] like Figure 2 As shown in , the controller's input X4 collects the normally open contact signals of the reset button SB1, the self-test button SB2, and the emergency stop button BT1, collects the normally open signal of the auxiliary contact of the circuit breaker, and the normally open contact series signal of KM1 and KM2 in the power module;

[0041] The controller's output terminals X2-1 and X2-3 are connected to the power module PM terminals respectively;

[0042] The analog input J9-1 of the controller is connected to LV11, J9-3 is connected to LV12, J9-5 is connected to LV13, and J9-5 is connected to the output terminal of LV14; the analog input J8-1 of the controller is connected to LA1, J8-3 is connected to LA2, and J8-5 is connected to the output terminal of LA3;

[0043] The controller's fiber optic interface TX1 is connected to the DRV-JS1 terminal, the TX2 fiber optic interface is connected to KZB1-RX1, the TX4 fiber optic interface is connected to KZB2-RX1, and the TX6 fiber optic interface is connected to KZB3-RX1; the RX1 fiber optic interface is connected to the fiber optic module KZB4-TX1 and finally connected to the transmitting end FS1 of the power module, which is used to receive the lower bridge fault signal of IPM1 and IPM2; the RX2 fiber optic interface is connected to KZB5-TX1 and finally connected to the transmitting end FS2 of the power module, which is used to receive the upper bridge fault signal of IPM1 and IPM2.

[0044] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0045] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low penetration device for air preheater of thermal power plant, characterized in that: Including incoming circuit breaker, current limiting reactor, power module, SCR thyristor module, load switch and controller; The incoming line circuit breaker, the current limiting reactor, the power module, the SCR thyristor module and the load switch are connected in sequence; the incoming line circuit breaker is used to connect an external power supply; the load switch is used to connect a frequency converter; The controller is communicatively connected with the power module and the thyristor module.

2. A low penetration device for air preheater of thermal power plant according to claim 1, characterized in that: The power module includes a plurality of power units connected in parallel; the power units are used for performing DC boosting and outputting the DC voltage to the SCR thyristor module.

3. A low penetration device for air preheater of thermal power plant according to claim 2, characterized in that: The power unit includes a three-phase rectifier bridge and a step-up transformer; external alternating current is converted into direct current through the three-phase rectifier bridge, and the direct current is stepped up through the step-up transformer.

4. A low penetration device for air preheater of thermal power plant according to claim 3, characterized in that: The step-up transformer adopts a boost circuit.

5. The low penetration device for air preheater of thermal power plant according to claim 3, characterized in that: The power unit also includes a current Hall element and a first voltage collection board; The current Hall element is used to collect the DC current converted by the three-phase rectifier bridge and transmit the current value to the controller; The voltage acquisition board is used to generate a conduction signal according to the voltage signal and the adjustment signal of the voltage sampling loop, and transmit the signal to the controller.

6. A low penetration device for air preheater of thermal power plant according to claim 5, characterized in that: It also includes a first optical fiber board and a second optical fiber board; the input end of the first optical fiber board is connected to the power module, and the output end is connected to the controller, so that the trigger signal is transmitted to the controller through the optical fiber; The input end of the second optical fiber board is connected to the controller, and the output end is connected to the power module, so that the control signal sent by the controller is transmitted to the power module through the optical fiber.

7. The low penetration device for air preheater of thermal power plant according to claim 6, characterized in that: The second optical fiber board includes three sub-optical fiber boards, which are used to control the three-phase triggering of the power module respectively.

8. The low penetration device for air preheater of thermal power plant according to claim 1, characterized in that: The SCR thyristor module includes a thyristor, a diode module and a second voltage collection board; The diode module includes a first diode and a second diode; the anode of the first diode is connected to the K pole of the thyristor, and the cathode is connected to the positive terminal of the inverter through the load switch; the anode of the second diode is connected to the negative terminal of the inverter, and the cathode is connected to the power module; The second voltage collection board collects the voltages of the A pole and the K pole of the thyristor respectively, detects the conduction status of the thyristor, and outputs a conduction signal to the controller.

9. The low penetration device for air preheater of thermal power plant according to claim 7, characterized in that: Also included is a third optical fiber board and a fourth optical fiber board; The input end of the third optical fiber board is connected to the thyristor module, and the output end is connected to the controller, so that the trigger signal of the thyristor module is transmitted to the controller through the optical fiber; The input end of the fourth optical fiber board is connected to the controller, and the output end is connected to the thyristor module, so that the control signal of the controller is transmitted to the thyristor module through the optical fiber.

10. The low penetration device for air preheater of thermal power plant according to claim 1, characterized in that: The controller includes a voltage sampling module, a current sampling module and an optical fiber interface.

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