JP2006329624A - Automatic boiler controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control pressure of air or combustion gas suitably for a thermal power generation plant with an inverter applied on a blower, and to favorably control a motor output. <P>SOLUTION: The automatic boiler controller is provided with a means for preparing a control command to a flow regulating operation end, based on proportional integration computation by a control deviation of pressure of the air or the combustion gas that is a control object, and for preparing a motor output control command by a program in response to a boiler load, a means for adding a bias by a program corresponding to the boiler load, to the control command to the flow regulating operation end, and a control means when switching a motor power source, and a control means in a single line operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a boiler automatic control device, and in particular, includes both an inverter and a commercial frequency power source as motor power, and has two systems of ventilators that use either power source by switching, and the flow rate of fluid passing through the ventilator The present invention relates to a boiler automatic control device that controls the pressure of air or combustion gas in a boiler to a specified value by a motor output control command to an inverter control device that controls a motor output of a flow rate adjusting operation end and a ventilator.

  Conventionally, a commercial frequency power supply has been used as power for a ventilator for a thermal power plant, and the motor output (rotational speed) of the ventilator is constant in a normal operation state. Accordingly, in the boiler automatic control device, the pressure in the furnace of the boiler is controlled by controlling the operation end for adjusting the flow rate of the fluid (air or combustion gas) passing through the ventilator.

  The above prior art does not consider the case where an inverter (frequency converter) is applied to a large-capacity ventilator for a thermal power plant, and in this case, pressure control of air or combustion gas and a motor output control method are established. There was a problem that not.

  An object of the present invention is to provide an automatic boiler control apparatus suitable for performing pressure control and motor output control of air or combustion gas suitable for a thermal power plant in which an inverter is applied to an air ventilator.

The above problem is to create a control command to the flow rate adjusting operation end based on a proportional integral calculation based on a control deviation of the pressure of air or combustion gas to be controlled, and to create a motor output control command by a program corresponding to the boiler load Means, a means for adding a bias by a program corresponding to the boiler load to the control command to the flow rate adjusting operation end, a means for adding a bias to the control command to the flow rate adjusting operation end when switching the motor power supply of the ventilator, When only one of the two ventilators is operated, the program corresponding to the boiler load added to the control command to the flow rate adjusting operation end and the program corresponding to the boiler load creating the motor output control command are switched. If one of the two systems is operated by an inverter and the remaining one is operated by a commercial frequency power supply, the commercial frequency power supply The means to hold the proportional integral calculation result to create the control command to the flow control operation end on the operation side, and the proportional integral calculation parameter to create the control command to the flow control operation end It is solved by providing means for switching depending on whether it is a commercial frequency power supply.

  As described above, according to the present invention, air or combustion gas pressure control and motor output control suitable for a thermal power plant in which an inverter is applied to a ventilator can be performed as follows.

  Create a control command to the flow control operation end based on proportional integral calculation based on the control deviation of the pressure of the air or combustion gas to be controlled, and create a motor output control command by a program according to the boiler load. The fast pressure control and the slow motor output control can be coordinated.

  By adding a bias by a program corresponding to the boiler load to the control command to the flow rate adjusting operation end, it is possible to operate at a flow rate adjusting operation end opening suitable for exhibiting the energy saving effect by the inverter operation. By adding a bias when switching the motor power supply of the ventilator to the control command to the flow rate adjusting operation end, it is possible to suppress pressure fluctuations during power supply switching.

  When only one of the two ventilators is operated, the program corresponding to the boiler load added to the control command to the flow rate adjusting operation end and the program corresponding to the boiler load creating the motor output control command are switched. As a result, even in the case of single system operation, it is possible to control the flow rate adjusting operation end opening and the motor output to be optimum.

  If one of the two ventilators is operated by an inverter and the remaining one is operated by a commercial frequency power supply, the proportional integration calculation result is generated to create a control command to the flow adjustment operation end on the operation side by the commercial frequency power supply. By doing so, stable pressure control can be performed even when one is operated by an inverter and the other is operated by a commercial frequency power supply.

  By switching the proportional integral calculation parameter to create a control command to the flow control operation end depending on whether the motor power supply of the fan is an inverter or a commercial frequency power supply, the two ventilators can be operated by an inverter or by a commercial frequency power supply, respectively. Stable pressure control can be performed in any state of operation.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 shows the configuration of a thermal power plant and a control device to which the present invention is applied. The thermal power plant includes a furnace 1 that burns fuel and generates steam by heat exchange, a forced air blower 2 (hereinafter abbreviated as “FDF”) that blows combustion air to the furnace 1, and combustion gas from the furnace 1. Induction fan 3 (hereinafter abbreviated as “IDF”), IDF motor 4 that is the power of IDF 3, IDF inlet damper 5 that adjusts the amount of gas sucked out by IDF 3, chimney 6, and pressure in furnace 1 It is comprised from the furnace pressure detector 7 which detects this. The power source of the IDF motor 4 includes a main power source 11, a circuit breaker 12, an inverter 8, a circuit breaker 13 and a circuit breaker 14 for inverter power supply, and a circuit breaker 15 for commercial frequency power supply.

  Here, there are two each of FDF2, IDF3, IDF motor 4, IDF inlet damper 5, inverter 8, circuit breaker 12, circuit breaker 13, circuit breaker 14, and circuit breaker 15, each constituting an independent system ( Hereinafter, the respective systems are referred to as A system and B system).

  The control device includes a boiler automatic control device 9 that performs comprehensive control of the process amount of the boiler, and an inverter control device 10 that performs output control of the inverter 8. In addition, although this embodiment demonstrates the case where an inverter is applied to the induction ventilator of a thermal power plant, air or combustion gas pressure control, such as an indentation ventilator and a primary ventilator (apparatus which blows the air for pulverized coal conveyance), etc. The boiler automatic control apparatus according to the present invention can be applied even when applied to other equipment related to the above.

  Next, the function of each element shown in FIG. 2 will be described.

  The air sent from the FDF 2 is used for combustion in the furnace 1 and becomes a combustion gas, and is sucked out by the IDF 3 and discharged from the chimney 6. Here, the furnace pressure in the furnace 1 must be controlled to a specified value for reasons of boiler safety or performance. An operation end for adjusting the amount of gas sucked out by the IDF 3 in order to control the furnace pressure is an IDF inlet damper 5.

  The boiler automatic control device 9 outputs an IDF inlet damper opening command 17 based on the furnace pressure signal 16 from the furnace pressure detector 7 and the calculation result of the control arithmetic circuit built in the boiler automatic control device 9 to output the IDF inlet damper 5. To control the furnace pressure. Further, the boiler automatic control device 9 outputs an IDF rotation speed command 18 based on the calculation result of the control calculation circuit.

  The boiler automatic control device 9 is a device that controls the generator output, steam temperature, pressure, and the like in addition to the above, but only functions related to the present invention will be described here.

  The inverter control device 10 outputs an inverter output command 19 based on the IDF rotation speed command 18 from the boiler automatic control device 9 to control the inverter 8, and the rotation speed (frequency) of the IDF motor 4 is changed from the boiler automatic control device 9. The IDF rotation speed command 18 is controlled to be the same.

  Driving power for the IDF motor 4 is supplied from the main power supply 11 having an AC commercial frequency via the circuit breaker 12 and the circuit breaker 13, the inverter 8, and the circuit breaker 14. However, when the inverter power supply becomes unusable due to a failure of the inverter 8 or the inverter control device 10, the circuit breaker 13 and the circuit breaker 14 are removed and the circuit breaker 15 is turned on, and the power supply line is connected from the inverter side. Has a backup function to switch to the commercial frequency power supply.

  Next, a detailed control function of the boiler automatic control device 9 will be described with reference to FIG.

  During normal plant operation (in both A and B systems, the IDF is operated by an inverter and the IDF inlet damper and IDF rotation speed control system are automatically controlled), input from the furnace pressure detector 7 The furnace pressure deviation signal 951 is calculated by the subtractor 901 from the furnace pressure signal 16 and the set value of the furnace pressure, and the furnace pressure deviation signal 951 is proportionally integrated by the proportional integration calculator 902 to obtain the furnace pressure control signal 952. create.

  Although the furnace pressure control signal is used to control the A system and the B system, since the downstream control circuit is the same for both the A system and the B system, only the control circuit for the A system is shown in FIG. After the furnace pressure control signal 952 passes through the signal switch 906, an adder 907 adds an IDF inlet damper opening correction signal 954 to become a final IDF inlet damper opening command 17, and this IDF inlet damper opening command 17 17 causes the IDF inlet damper 5 to operate.

  On the other hand, it is set by the function generator 915 based on the boiler input command (command signal that regulates the amount of water supply, fuel, and air to be supplied to the boiler according to the amount of power generation, hereinafter abbreviated as “BID”) 955. The IDF rotational speed program 956 passes through the signal switch 917 and the change rate limiter 918, and is then output to the inverter control device 10 as the IDF rotational speed command 18, and after the inverter controller 10 performs control calculation, the inverter output command The output of the inverter 8 is controlled as 19, and the rotational speed of the IDF motor 4 is controlled to the value of the IDF rotational speed command 18 from the boiler automatic control device.

  As described above, the furnace pressure control with quick response is performed by the IDF inlet damper, and the IDF rotation speed control is the program control, whereby the furnace pressure control and the IDF rotation speed control can be coordinated.

  Here, the IDF inlet damper opening correction signal 954 will be described. The IDF inlet damper opening correction signal 954 is for keeping the IDF inlet damper opening during the inverter operation in the set operation opening range, and the IDF set by the function generator 908 based on the BID955. The inlet damper opening correction program 957 passes through the signal switcher 910, the adder 911, the signal switcher 913, and the change rate limiter 914, and is then added to the furnace pressure control signal by the adder 907 to be the final IDF inlet damper. The opening command 17 is obtained.

  The open bias signal 958 added by the adder 911 turns off the circuit breaker 13 and the circuit breaker 14 when the inverter power supply becomes unusable due to a failure of the inverter 8 or the inverter control device 10, etc. Although the power supply line is switched from the inverter side to the commercial frequency power source side, the IDF motor 4 naturally decelerates while the circuit breaker 13 and the circuit breaker 14 are removed and the circuit breaker 15 is turned on. In order to suppress the rise, the IDF inlet damper 5 is opened in advance.

  The same applies to switching from the commercial frequency power supply side to the inverter side. As for the open bias signal 958, the α% side is selected by the signal switcher 912 during the above period, and the 0% side is selected except during the above period.

  Further, when the inverter is not used, that is, when the IDF motor 4 is driven by a commercial frequency power supply, the IDF inlet damper opening correction signal 954 is not necessary, so the signal switcher 913 selects the 0% side.

  As described above, the IDF inlet damper opening correction circuit can be operated with an IDF inlet damper opening suitable for inverter operation.

  Depending on the plant operating situation, only the A system or the B system may be operated, so-called ventilation system single system operation may be performed. In this case, since the IDF rotational speed program set based on BID 955 needs to be different from that during normal A-system and B-system operation, the signal switching unit 917 causes BID 955 on the operating side. Is selected by the function generator 915 and the IDF rotational speed program 959 is set by the function generator 909 based on the BID 955 by the signal switcher 910. A correction program 960 is selected.

  As described above, by providing a control circuit for ventilation system single operation, optimum IDF inlet damper and IDF rotation speed control can be performed even in the case of ventilation system single operation.

  When one of the two IDFs of the A system and the B system is operated by an inverter and the other is operated by a commercial frequency power supply, the loop gain of the furnace pressure control, that is, the loop gain of the IDF inlet damper control is A It differs between the system and the system B.

  On the other hand, the proportional integrator for the furnace pressure signal and furnace pressure control is common to the A system and the B system, and in order to remove the unstable factor of the automatic control due to the difference in the control loop gain, In the system operated by the above, the signal switch 906 selects the output signal 953 side of the signal switch 906 itself. That is, the furnace pressure control signal 952 that is the output of the proportional-plus-integral calculator 902 is valid only on the inverter operation side.

  As described above, stable furnace pressure control can be performed even when one of the IDFs of the A system and the B system is operated by an inverter and the other is operated by a commercial frequency power supply. it can.

  The control gain, which is a parameter of the proportional-plus-integral calculator 902, is controlled by the signal switching unit 905 when both the A system and the B system are operated with the commercial frequency power supply or one is operated with the commercial frequency power supply and the other is stopped. In the case of the state, the output signal side of the signal generator 903 is selected. When both the A system and the B system are operated by the inverter or when one is operated by the inverter and the other is stopped, the function generator is based on the BID 955. The signal side set by 904 is selected. In addition, the signal side set by the function generator 904 is also selected when one is operated by an inverter and the other is operated by a commercial frequency power supply.

  As described above, it is possible to perform stable furnace pressure control even if the IDFs of the two systems, A system and B system, are each operated by an inverter or operated by a commercial frequency power supply.

  Here, when the inverter power supply becomes unusable due to a failure of the inverter 8 or the inverter control device 10, the circuit breaker 13 and the circuit breaker 14 are removed, the circuit breaker 15 is turned on, and the power supply line is commercialized from the inverter side. The operation of the IDF inlet damper opening command 17 and the IDF rotation speed command 18 when switching to the frequency power supply side will be described with reference to FIG.

  FIG. 3 shows an example in which the A system side is switched from the inverter operation to the commercial frequency power supply from the state of both the A system and the B system inverter operation. In the normal state before switching, the IDF inlet damper opening command 17 is a signal obtained by adding the furnace pressure control signal 952 and the IDF inlet damper opening correction program 957. When the A-system circuit breaker 13 and the circuit breaker 14 are removed, the A-system IDF motor 4 is naturally decelerated because there is no power source.

  Next, an open bias signal 958 is added to the IDF inlet damper opening command 17 until the A-system breaker 15 is turned on. After the A circuit breaker 15 is turned on and the operation is switched to the commercial frequency power supply, the IDF inlet damper opening correction signal 954 decreases toward 0%, and the IDF inlet damper opening command 17 is sent by the signal switch 906. The retained signal 953 is obtained. A similar control operation is performed when switching from operation using a commercial frequency power supply to operation using an inverter.

  As described above, when the IDF operation is switched from the inverter to the commercial frequency power supply or vice versa, the IDF inlet damper operates properly according to the change in the IDF rotation speed, so that the fluctuation of the furnace pressure is minimized. Can be suppressed.

  As described above, in the present embodiment, the furnace pressure control is performed by the IDF inlet damper and the IDF rotation speed control is the program control, the IDF inlet damper opening correction circuit, and the control circuit for the ventilation system single system operation. By providing a control switching circuit depending on whether the IDF is an inverter operation or a commercial frequency power supply, and a control command correction circuit for switching the operation state of the IDF from the inverter to the commercial frequency power supply or from the commercial frequency power supply to the inverter, It is possible to optimally control the furnace pressure and IDF rotation speed of a thermal power plant in which an inverter is applied to the IDF.

It is a control function block diagram of the boiler automatic control apparatus in one Embodiment of this invention. It is a lineblock diagram of a thermal power plant and a control device in one embodiment of the present invention. It is control operation explanatory drawing of the boiler automatic control apparatus at the time of the power supply switch from the inverter to the commercial frequency power supply in one Embodiment of this invention.

Explanation of symbols

1. Furnace 2. Intrusion ventilator (FDF)
3. Induction fan (IDF)
4). IDF motor5. 6. IDF inlet damper Furnace pressure detector8. Inverter 9. Boiler automatic control device 10. Inverter control device 11. Main power supply 16. Furnace pressure signal 17. IDF inlet damper opening command 18. IDF rotational speed command 19. Inverter output command

Claims (6)

  The motor has both an inverter and a commercial frequency power source as motor power, and has two systems of ventilators that use either one of the power sources by switching, a flow rate adjusting operation end that adjusts the flow rate of fluid passing through the ventilator, and the ventilator In the boiler automatic control device that controls the pressure of air or combustion gas in the boiler to a specified value by the motor output control command to the inverter control device that controls the motor output, the control deviation of the pressure of the air or combustion gas to be controlled A boiler automatic control comprising: means for creating a control command to the flow rate adjusting operation end based on a proportional-integral calculation by; and means for creating the motor output control command by a program corresponding to a boiler load. apparatus.   2. The boiler automatic control device according to claim 1, wherein the control command to the flow rate adjusting operation end is obtained by adding a bias according to a program corresponding to a boiler load.   3. The boiler automatic control device according to claim 1, wherein the control command to the flow rate adjusting operation end is obtained by adding a bias when the motor power supply of the ventilator is switched.   The program according to any one of claims 1 to 3, wherein a boiler load is added to a control command to the flow rate adjusting operation end when only one of the two ventilators is operated. And the boiler automatic control apparatus characterized by switching the program according to the boiler load which produces the said motor output control instruction | command.   5. The flow rate on the operation side by a commercial frequency power source when one of the two ventilators is operated by an inverter and the remaining one system is operated by a commercial frequency power source according to claim 1. An automatic boiler control apparatus that holds the result of the proportional-integral calculation for creating a control command to an adjustment operation end. 6. The method according to claim 1, wherein the parameter of the proportional-integral calculation for creating a control command to the flow rate adjusting operation terminal is switched depending on whether the motor power supply of the ventilator is an inverter or a commercial frequency power supply. Boiler automatic control device.

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