Control system for switching frequency conversion to power frequency of primary air fan

Abstract

The utility model provides a control system for switching frequency conversion to power frequency of a primary fan, which is characterized in that the sum of the real-time values of the electric load corresponding to four-extraction external steam supply and the current electric load of a unit is used as the total load to correspond to the primary fan inlet regulating valve joint closing valve position control, and a valve closing opening degree instruction is sent out through a function corresponding relation. And sufficient primary air pressure can be ensured, and tripping of the coal mill is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of power station boilers, in particular to a safety lifting device for frequency conversion and power frequency cutting of a primary fan of a power station boiler. Background Art

[0002] The primary fan is an important auxiliary equipment of the power station boiler. It is generally operated with variable frequency. The primary fan inlet regulating door is fully open, and the primary air pressure is controlled by the primary fan variable frequency control. When the frequency converter fails and switches to industrial frequency operation, the primary fan inlet regulating door is associated with the specified opening according to the current unit electrical load to ensure the safety and stability of the unit's primary air pressure. However, for large heating units, heating is also obtained by the energy consumption of the unit. If this part is not counted in the electrical load, once the primary fan variable frequency is switched to industrial frequency, it is very easy to cause the low primary air pressure protection to be activated, resulting in the tripping of the coal mill and causing a boiler fire extinguishing accident. Utility Model Content

[0003] The utility model aims to provide a primary fan frequency conversion and power frequency control system, which can not only ensure the stability of the unit when a fault occurs, but also provide sufficient wind pressure to prevent the coal mill from tripping.

[0004] In order to achieve the above-mentioned purpose, the utility model is realized through the following technical solutions:

[0005] A primary fan variable frequency switching control system comprises a fan regulating unit, a fault shutdown unit and a load calculation unit. The fan regulating unit comprises an electric regulating door at the primary fan inlet. The fault shutdown unit comprises a fault logic circuit. The input end of the fault logic circuit is respectively connected to the primary fan inverter serious fault signal, the circuit breaker opening position signal and the bypass cabinet closing state signal, and the output is connected to the electric regulating door at the primary fan inlet. The load calculation unit comprises a calculation circuit. The input end of the calculation circuit is respectively connected to the actual load of the unit and the external heat supply extraction steam flow, and the output end is connected to the input end of the fault logic circuit. The calculation circuit is an adder.

[0006] Preferably, the fault logic circuit includes a logic AND gate, a logic OR gate, a first selector, and a second selector. The two input ends of the logic AND gate are respectively connected to the inversion of the primary fan inverter serious fault signal and the bypass cabinet closing status signal, the two input ends of the logic OR gate are respectively connected to the output end of the logic AND gate and the circuit breaker opening position signal, the output end of the logic OR gate is connected to the TS input end of the primary fan inlet electric regulating door, the selection input end of the first selector is connected to the output end of the logic AND gate, the a input end and the b input end of the first selector are respectively connected to the primary fan inlet electric regulating door valve position signal and the load calculation unit output end, the selection input end of the second selector is connected to the circuit breaker opening position signal, the a input end and the b input end of the second selector are respectively connected to the output end of the first selector and logic 0, and the output end of the second selector is connected to the TP input end of the primary fan inlet electric regulating door.

[0007] Preferably, the inversion of the bypass cabinet closing state signal is connected to the logic AND gate through the shutdown delay device, the circuit breaker opening position signal is connected to the logic OR gate and the second selector through the first pulse timer, and the output end of the logic AND gate is connected to the logic OR gate and the first selector through the second pulse timer.

[0008] Preferably, one input end of the adder of the load calculation unit is connected to the actual load of the unit, and the other input end is connected to the output end of the first broken line function module, the input end of the first broken line function is connected to the external heat extraction steam flow, the output end of the adder is connected to the input end of the second broken line function module, and the output end of the second broken line function module is connected to the b input end of the first selector.

[0009] Preferably, the delay time of the shutdown delay device is 1 second, the delay time of the first pulse timer is 60 seconds, and the delay time of the second pulse timer is 55 seconds.

[0010] The advantages of the utility model are as follows: the electric load corresponding to the four-extraction external steam supply is added to the real-time value of the current electric load of the unit as the total load corresponding to the joint closing valve position control of the primary fan inlet regulating valve, and the valve closing opening instruction is issued through the function correspondence. For large heating units, it can ensure sufficient primary wind pressure and avoid coal mill tripping. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a logic schematic diagram of the utility model. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0013] This embodiment discloses a primary fan frequency conversion and power frequency control system. Please refer to Figure 1, including a fan adjustment unit, a fault shutdown unit and a load calculation unit. The fan adjustment unit includes an electric adjustment door for the primary fan inlet. The fault shutdown unit includes a fault logic circuit. The input end of the fault logic circuit is respectively connected to the primary fan inverter serious fault signal, the primary fan 6kV circuit breaker opening position signal and the primary fan inverter local bypass cabinet KM3 closing status signal.

[0014] Specifically, the fault logic circuit includes a logic AND gate, a logic OR gate, a first selector, and a second selector. The two input ends of the logic AND gate are respectively connected to the serious fault signal of the primary fan inverter and the output end of the shutdown delay device. The input end of the shutdown delay device is connected to the inversion of the closing state of the local bypass cabinet KM3 of the primary fan inverter. The shutdown delay is 1 second. The two input ends of the logic OR gate are respectively connected to the output end of the first pulse timer and the output end of the second pulse timer. The input end of the first pulse timer is connected to the opening position signal of the primary fan 6kV circuit breaker, and the delay time is 60 seconds. The input end of the second pulse timer is connected to the output end of the logic AND gate, and the delay time is 55 seconds. The output end of the logic OR gate is connected to the TS input end of the electric regulating door at the primary fan inlet.

[0015] One input end of the adder of the load calculation unit is connected to the actual load of the unit, and the other input end is connected to the output end of the first broken line function module. The input end of the first broken line function is connected to the external heat extraction steam flow. The output end of the adder is connected to the input end of the second broken line function module, and the output end of the second broken line function module is connected to the b input end of the first selector.

[0016] The selection input of the first selector is connected to the output of the second pulse timer, the a input of the first selector is connected to the valve position signal of the electric regulating door at the primary fan inlet, the selection input of the second selector is connected to the output of the first pulse timer, the a input and b input of the second selector are connected to the output of the first selector and logic 0 respectively, and the output of the second selector is connected to the TP input of the electric regulating door at the primary fan inlet.

[0017] During operation, if the bypass cabinet is opened, the shutdown delay device output is 1. If a serious fault occurs in the inverter, the two inputs of the logic AND gate are 1, the output is 1, and the fan is disconnected after the second pulse timer delay; when the primary fan circuit breaker opening position signal is 0, the fan is also disconnected through the first pulse timer and the logic OR gate.

[0018] When the fan is operating normally, the joint closing valve position control of the primary fan inlet regulating valve corresponds to the total load of the electric load corresponding to the four-extraction external steam supply and the real-time value of the current electric load of the unit added by the adder, and the valve closing opening instruction is issued through the function correspondence. And after experimental demonstration, the proportional relationship between the four-extraction external steam supply flow and the electric load is determined, and the final proportional relationship is 4:1, that is, 40T / h steam supply flow corresponds to 10MW electric load.

[0019] Finally, it should be noted that the above is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A primary fan frequency conversion and power frequency control system, characterized in that: It includes a fan regulating unit, a fault shutdown unit and a load calculation unit. The fan regulating unit includes an electric regulating door at the inlet of a primary fan. The fault shutdown unit includes a fault logic circuit. The input end of the fault logic circuit is respectively connected to the primary fan inverter serious fault signal, the circuit breaker opening position signal and the bypass cabinet closing state signal, and the output is connected to the electric regulating door at the inlet of the primary fan. The load calculation unit includes a calculation circuit. The input end of the calculation circuit is respectively connected to the actual load of the unit and the external heat extraction steam flow, and the output end is connected to the input end of the fault logic circuit. The calculation circuit is an adder.

2. According to the primary fan frequency conversion and power frequency control system of claim 1, it is characterized in that: The fault logic circuit includes a logic AND gate, a logic OR gate, a first selector, and a second selector. The two input ends of the logic AND gate are respectively connected to the inversion of the primary fan inverter serious fault signal and the bypass cabinet closing state signal, the two input ends of the logic OR gate are respectively connected to the output end of the logic AND gate and the circuit breaker opening position signal, the output end of the logic OR gate is connected to the TS input end of the primary fan inlet electric regulating door, the selection input end of the first selector is connected to the output end of the logic AND gate, the a input end and the b input end of the first selector are respectively connected to the valve position signal of the primary fan inlet electric regulating door and the output end of the load calculation unit, the selection input end of the second selector is connected to the circuit breaker opening position signal, the a input end and the b input end of the second selector are respectively connected to the output end of the first selector and logic 0, and the output end of the second selector is connected to the TP input end of the primary fan inlet electric regulating door.

3. The primary fan frequency conversion and power frequency control system according to claim 2 is characterized in that: The inversion of the bypass cabinet closing state signal is connected to the logic AND gate through the shutdown delay device, the circuit breaker opening position signal is connected to the logic OR gate and the second selector through the first pulse timer, and the output end of the logic AND gate is connected to the logic OR gate and the first selector through the second pulse timer.

4. The primary fan frequency conversion and power frequency control system according to claim 2 is characterized in that: One input end of the adder of the load calculation unit is connected to the actual load of the unit, and the other input end is connected to the output end of the first broken line function module, the input end of the first broken line function is connected to the external heat extraction steam flow, the output end of the adder is connected to the input end of the second broken line function module, and the output end of the second broken line function module is connected to the b input end of the first selector.

5. The primary fan frequency conversion and power frequency control system according to claim 3 is characterized in that: The delay time of the shutdown delay timer is 1 second, the delay time of the first pulse timer is 60 seconds, and the delay time of the second pulse timer is 55 seconds.

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