JP2005299955A - Boiler control device - Google Patents

Abstract

An output change rate obtained by a boiler control device fluctuates little by little when the period of a pulse given from a remote control station to a power plant is not constant or the given pulse width is not constant. Unnecessary disturbance.
In a boiler control device, an output change amount calculating means for determining an output increase / decrease amount from a pulse width detecting means for integrating a pulse length c of a remote control signal a sent from a remote control station to a power plant. Since the processing up to 23 and the subsequent processing of the output target value setting means 24 are separated, the output change amount calculating means 23 of the preceding stage is calculating the output change rate by the output target value setting means 24 of the latter stage. The length of the pulse of the remote control signal that arrives next can be integrated.
[Selection] Figure 1

Description

  The present invention relates to a boiler control device used in a power plant, and more particularly to a boiler control device that performs control using a remotely operated pulse waveform signal.

  In general, in a thermal power plant, fuel is burned in a boiler to generate steam from water, and this steam is introduced into a steam turbine and adiabatically expanded to generate electricity from the generator via the steam turbine.

  In order to control the electricity generated by the generator, that is, the generator output, the rotational energy is adjusted by increasing or decreasing the amount of steam supplied to the steam turbine by adjusting the opening of the steam control valve installed at the inlet of the steam turbine. At the same time, in order to increase or decrease the amount of steam generated from the boiler, the boiler feed water flow rate, the boiler input fuel, and the amount of air necessary for the boiler input fuel to burn are controlled.

  A boiler control device controls these boiler feed water flow rate, boiler input fuel, and air quantity. In order to increase the amount of steam generated from the boiler, it is necessary to increase the boiler feed water flow rate, increase the amount of fuel input, and further increase the amount of air fed so that the increased fuel combustion is performed stably. However, in general, there is a response delay determined by the characteristics of the boiler from when these operations are performed until the amount of generated steam actually increases.

  In order to compensate for this response delay by control, there is a preceding control (generally referred to as BIR control) in which a value calculated using the output target value of the generator or the output change rate is added to the normal output command. (For example, refer to Patent Document 1). By adopting this advance control, the followability of the boiler can be improved with respect to the increase / decrease request of the generator output, and the turbine generator can be stably operated.

Normally, the generator output is set by the operator setting the output target value using an output setting device installed in the boiler control device, and a remote control station (external to the power plant) such as a central power supply command station. In some cases, the operation is performed by setting the output target value by remote control. The role of the central power supply command station is to determine the required output value of the power station that it is in charge of and issue a command to the power station in order to supply power corresponding to the ever-changing power demand. is there. The command (remote control command) from the central power supply command station is made by predicting the power demand, and the predicted time is determined by dividing the time from 5 minutes ahead. The output request value after 5 minutes of the power plant is determined every time and is output to the power plant as a remote control command. As described above, there are a method for receiving the output request value as an analog amount, a method for receiving the contact command for increasing / decreasing the target value, and the like as a method for signal sharing when the output target value in the boiler control device is set by remote control.
Japanese Patent Laid-Open No. 2002-228103 (2nd page, FIG. 3)

  When setting the output target value of the above-mentioned boiler control device by remote control, load increase command and decrease command are input by pulse waveform signal respectively, and output from the time (pulse width) when the pulse waveform signal is ON In some cases, the increase / decrease amount of the target value and the output change rate were determined. In the driving operation using the preceding control, it is a necessary condition for performing stable control that the output change rate during output change, particularly during output increase, is constant. In other words, when determining the output change rate from the pulse waveform signal of the remote operation signal, if the pulse waveform signal is given at a constant cycle and the same pulse width, the output target value will increase at a constant rate. Becomes stable and stable control can be performed.

  However, when the period of the given pulse is not constant, or when the given pulse width is not constant, the required output change rate fluctuates little by little, which is an unnecessary disturbance for the boiler control device. For example, the output request value of the remote control station is updated every 5 minutes, and when the output request value is updated to a value larger than the current generator output, the difference between the output request value and the generator output is large. The pulse waveform signal of the remote control command is continuously transmitted to bring it closer to the required output value, but when the generator output approaches the required output value, the pulse width decreases, and when the required output value is reached, the pulse waveform signal is transmitted. It will not be done. When a new output request value is updated after 5 minutes, the remote control command pulse waveform signal is transmitted again.

  In this case, the movement of the output target value inside the boiler control device changes from increase → constant → increase → constant, and the output change rate changes from value X → 0 → value X → 0. Such a movement occurs every 5 minutes, but if it is viewed in a little longer time, the load continues to increase, and it is required to control the boiler with good followability using the advance control. However, when the advance control is used, since the output change rate fluctuates, a disturbance is generated and the controllability may be deteriorated. Thus, how to suppress the fluctuation of the output change rate is a problem.

  Further, since the output change rate is obtained from the pulse width, the increase / decrease amount of the output target value cannot be determined until the pulse width (time from ON to OFF) is determined, and the output change rate cannot be calculated. In addition, since the pulses are transmitted one after another, it is necessary to efficiently execute the process of obtaining the output change rate by appropriately inputting the pulses to obtain the increase / decrease amount of the output target value.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a boiler control device capable of performing optimum boiler operation in operation using boiler advanced control based on remotely operated pulse waveform signals. And

  In order to achieve the above object, the boiler control device according to claim 1 detects a pulse width by inputting a remote control signal of a pulse waveform sent from a remote control station, and the remote control signal is A remote control signal input processing means having a function of determining whether or not it is normally input and detecting that a next remote control signal is input, and detected by the remote control signal input processing means Output change amount calculating means for calculating the output increase / decrease amount based on the pulse width, output target value setting means for setting the power generation output target value in response to the output increase / decrease amount, and the power generation set by the output target value setting means Output change rate calculating means for calculating an output change rate based on increase / decrease of the output target value, output command calculating means for calculating an output command based on the power generation output target value and the output change rate, and the output command calculating means A boiler advance control amount calculating means for calculating a boiler advance control amount based on the output command output and the output change rate, and an air control system by a boiler output command obtained by adding the output command and the boiler advance control amount Further, the present invention is characterized in that a set value of a fuel control system, a feed water control system, and a steam turbine output control system is calculated to control a boiler generated steam amount and a steam turbine inflow steam amount.

  According to this embodiment, the processing from the pulse width detection means for integrating the pulse width length of the remote control signal sent from the remote control station to the power plant to the output change amount calculation means for determining the output increase / decrease amount, Since it is configured to separate the subsequent processing of the output target value setting means, the remote control that reaches the next by the output change amount calculation means of the preceding stage while calculating the output change rate by the output target value setting means of the latter stage As a result, it is possible to provide a boiler control apparatus that can perform optimum boiler operation without causing unnecessary disturbance.

Hereinafter, a boiler control device according to a first embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, first, the configuration of the present embodiment will be described.
1 is a remote control station such as a central power supply command station, 2 is a boiler control device, 3 is a power plant (power plant) in which a boiler B, a steam turbine T, and a generator G controlled by the boiler control device 2 are installed. . Reference numeral 31 denotes an input device for an operator to make various settings for the boiler control device 2.

  The boiler control device 2 includes an operation mode switch 301 for switching whether the power plant operator uses the input device 31 to set the generator output on the power plant side or the remote control station, A power generation output setting device 302 for setting the machine output and an output change rate setting device 303 for setting the output change rate are provided.

  The boiler control device 2 also includes a signal input means 21 for inputting a remote control signal a having a pulse waveform for operating the power generation output of the power plant 3 from the remote control station 1 such as a central power supply command station, and the signal input means 21 The pulse width detection means 22 for detecting the pulse width c of the input pulse by inputting the pulse waveform signal b output from the input signal, and whether the remote control signal a is normally input by inputting the pulse waveform signal b. A remote control signal input processing means 20 having an input signal abnormality judging means 211 for judging and a next pulse detecting means 221 for detecting that the next new pulse b to be inputted is inputted, and outputted from the pulse width detecting means 22 An output change amount calculating means 23 for obtaining an output increase / decrease amount e based on the pulse width c, and an output target value setting for setting the power generation output target value f0 by inputting the output increase / decrease amount e obtained by the output change amount calculating means 23 And a power change rate calculating means 25 for obtaining an output change rate g0 by increasing or decreasing the power generation output target value fo.

  Furthermore, when the remote control station 1 is selected by the operation mode switch 301, the boiler control device 2 calculates the power generation output target value f0 (fs) output from the output target value setting means 24 and the output change rate calculation. The output command calculating means 26 for obtaining the output command h by inputting the output change rate g0 (gs) output from the means 25, and the boiler preceding control amount i by inputting the output command h and the output change rate gs. A boiler preceding control amount calculating means 27 to be obtained is provided.

  Furthermore, the boiler control device 2 performs an air control system 291 that performs individual control of air, fuel, and the like by a boiler output command j obtained by adding the output command h and the boiler preceding control amount i by the adding unit 28. A fuel control system 292, a water supply control system 293, and a steam turbine output control system 294 are provided.

Next, the operation of this embodiment will be described.
When the operator of the power plant 3 selects the operation mode switch 301 on the power plant side by the input device 31, the power generation output target value fs is selected by the switch 301-1 on the power generation output setting device 302 side. Further, the output change rate gs is selected by the switch 301-2 as a value on the output change rate setting unit 303 side.

  The remote control station 1 transmits to the power station the increase / decrease amount of the power generation output and the output change rate based on the pulse length of the transmitted remote control signal a. The pulse length is, for example, the shortest 0.5 seconds, the longest 3.5 seconds, and the weight of the power generation output per 0.5 second length of the pulse waveform signal is 0.15 MW. Note that the command for increasing the output and the command for decreasing the output are given as separate input signals. Further, the power generation output of the power plant 3 is determined every 5 minutes in order to meet the power demand that changes every moment.

  The signal input means 21 is an input part for taking in the remote control signal a into the boiler control device, and captures the change in the rise time of the remote control signal a from OFF to ON or the fall time from ON to OFF. The time of change is notified to the pulse width detection means 22, or the state of the input pulse is periodically updated, and the updated ON / OFF information b is notified to the pulse detection means 22.

The pulse width detector 22 integrates the time during which the input pulse waveform signal b is ON, and notifies the output change amount calculator 23 of the pulse length c.
The input signal abnormality determination means 211 is used when the pulse waveform signal b input from the signal input means 21 is ON for longer than the specified time, or when the increasing signal and decreasing signal are simultaneously ON. Then, it is determined that the input signal is abnormal, and the signal abnormality d is notified to the output variation calculation means 23.

  The next pulse detection means 221 detects that the subsequent new pulse waveform signal b has been input, detects that the pulse waveform signal has changed from OFF to ON, and outputs the next pulse notification c1 as an output change amount calculation means. Notify 23. Also, when the next pulse does not come even after the lapse of the specified time, the next pulse notification c1 is notified to the output change amount calculation means 23.

  The output change amount calculation means 23 converts the pulse length c obtained by the pulse width detection means 22 into an output increase / decrease amount e and notifies the output target value setting means 24 only when the signal abnormality d is not notified. To do. If the signal abnormality d is notified from the input signal abnormality determination unit 211, the converted output increase / decrease e is cleared to 0 and the output increase / decrease e is not operated. Further, the output change amount calculation means 23 does not notify the output increase / decrease amount e during the integration of the pulse length c, but does not notify it, and is performed when the next pulse notification c1 comes.

  By this mechanism, the processing from the pulse width detection means 22 for integrating the pulse length c to the output change amount calculation means 23 for determining the output increase / decrease amount is separated from the subsequent processing of the output target value setting means 24. During the calculation of the output change rate by the output target value setting means 24 at the subsequent stage, the output change amount calculating means 23 at the preceding stage realizes the integration processing of the pulse length of the next pulse input to be reached.

  The output target value setting means 24 receives the output increase / decrease amount e converted by the output change amount calculation means 23, and increases / decreases the power generation output target value f0. The increase / decrease of the power generation output target value f0 is performed by an integration circuit. For example, when a change amount in the increasing direction of 0.6 MW is notified, the power generation output target value f0 operates to increase by 0.6 MW in 4 seconds.

  The output change rate calculating means 25 calculates the output change rate g0 from the power generation output target value f0 set by the output target value setting means 24. The output change rate calculating means 25 is composed of a change rate calculating means 251 and a change rate decrease restricting means 252. These means are each constituted by a plurality of elements as shown in the detailed configuration diagram of FIG. .

  In FIG. 2, the change rate calculation means 251 inputs the captured power generation output target value f0 to the dead time circuit 41 and delays it by the set time t1 to generate the output f1, in other words, based on the current time. At this time, the power generation output target value f0 (= f1) before time t1 is output.

  FIG. 3 is an input / output waveform diagram of the dead time circuit 41. If the dead time is set to t1 = 4 seconds, for example, the signal f0 input during a certain time T1 to T2 is output as the output signal f1 during the time (T1 + 4 to T2 + 4) without changing the signal waveform. Then, the subtracter 42 subtracts the power generation output target value f1 of 4 seconds before from the current power generation output target value f0, so that the difference in time of 4 seconds, that is, the amount of change in power generation output target value in 4 seconds f2 = (f0− f1) is obtained.

  This output change amount f2 becomes a positive value while the output is increasing, but becomes a negative value when the output is decreasing. Therefore, the absolute value circuit 43 in the next stage calculates an output change amount absolute value f3 of only a positive value. Ask. This output change amount absolute value f3 is a change amount per 4 seconds (MW / 4 seconds), and the change amount per minute (MW / min), which is a unit used for control by the conversion circuit 44. Convert to. The obtained output change rate g1 is input to the change rate decrease limiting means 252.

  The output change rate g1 input to the change rate decrease limiting means 252 is input to the limit value calculation circuit 45. In this embodiment, a first-order lag function is employed as the limit value calculation circuit 45. FIG. 4 shows an input / output waveform diagram of the first-order lag function. The first-order lag function is a function that generates an output that rises with a predetermined time constant and reaches a steady value after a specified time when a step-like input signal is applied. The output change rate g2 output from the limit value calculation circuit 45 and the output change rate g1 output from the conversion circuit 44 are input to the optimum value selection circuit 46. Here, the optimum value selection circuit 46 is a circuit that outputs an optimum value for control at that time out of one of two input output change rates g1 and output change rates g2, and is the optimum value in this embodiment. A small value is a larger value (high value) of two values, and a high value is selected and output as an output change rate g0.

  The operation of the change rate reduction limiting means 252 will be described with reference to the input / output waveform diagram of FIG. When the output rate of change g1 is increasing (rising of g1), the output rate of change g2, which is the output of the limit value calculation circuit 45, is smaller than the output rate of change g1, so the rate-of-change decrease limiting means 252 Although the rate g1 is selectively output, when the output change rate is decreasing (falling g1), the value of the output change rate g2 is selected and output, so that there is an effect of reducing fluctuations in the output change rate g0.

  Returning to FIG. The output command calculation means 26 inputs the output target value fs (= f0) obtained by the output target value setting means 24 and the actual generator output k and determines the output command h. The output target value fs Is larger than the generator output k (fs> k), the output command h in the increasing direction is generated because the generator output k needs to be increased. Conversely, the output target value fs is the generator output k. When the state is smaller (fs <k), the output command h is generated in the decreasing direction because the output needs to be decreased. The output command h increases or decreases at a constant change rate determined based on the output change rate gs (= g0) output from the output change rate calculating means 25.

  In order to minimize the time delay until additional injection of fuel, etc. appears as a result of boiler output, boiler advanced control amount calculation means 27 adds additional injection as the load increases in addition to the amount of fuel currently required. A stable load change can be realized by adding necessary fuels in advance and at an accelerated rate. The boiler preceding control amount i is a value calculated mainly using the output change rate gs for the output command h. The adder 28 adds the output command h and the boiler advance control amount i to obtain the boiler output command j.

  The obtained boiler output command j is input to the air control system 291, the fuel control system 292, the feed water control system 293 and the steam turbine output control system 294, respectively, so that the air system set value, the fuel system set value, the feed water system set value The steam turbine system set value is obtained by calculation, and the boiler generated steam amount is controlled by performing feed water control, fuel control, and air control of the boiler B based on these set values, and the control of the inflow steam amount of the steam turbine T To control the generator output.

  As described above, according to the present embodiment, the output change amount calculation for determining the output increase / decrease amount from the pulse width detecting means for integrating the pulse width length of the remote control signal sent from the remote control station to the power plant. Since the processing up to the means 23 and the subsequent processing of the output target value setting means 24 are separated, the output change amount calculation of the preceding stage is performed while the output change rate is being calculated by the output target value setting means of the subsequent stage. It is possible to integrate the length of the pulse of the remote control signal that arrives next by means, and as a result, it is possible to provide a boiler control device that does not cause unnecessary disturbance.

  Further, since the output change rate calculating means 25 is provided with the change rate reduction limiting means 252 so as not to suddenly change when the pulse waveform signal falls, the output command h is prevented from changing rapidly. Therefore, it is possible to smoothly control the boiler generated steam amount and the steam turbine inflow steam amount.

  In the embodiment described above, it is not mentioned whether or not the remote control signal sent from the remote control device is a multiplexed pulse waveform signal, but the pulse waveform signal sent from the remote control station is not mentioned. Is multiplexed, the function of selecting the multiplexed pulse waveform signal may be added to the signal input means 21 in the remote control signal input processing means 20.

The block diagram of the boiler control apparatus by one Example of this invention. The detailed block diagram of the output change rate calculating means of FIG. The input / output waveform diagram of the dead time circuit of FIG. The input / output waveform diagram of the limit value calculation circuit of FIG. FIG. 3 is an input / output waveform diagram of the output change rate reduction limiting means of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Remote control station, 2 ... Boiler control device, 3 ... Power generation plant, 20 ... Remote control signal input processing means, 21 ... Signal input means, 22 ... Pulse width detection means, 221 ... Next pulse detection means, 211 ... Input signal Abnormality determining means, 23 ... output change amount calculating means, 24 ... output target value setting means, 25 ... output change rate calculating means, 26 ... output command calculating means, 27 ... boiler advanced control amount calculating means, 291 ... air control system, 292 ... Fuel control system, 293 ... Feed water control system, 294 ... Steam turbine output control system, 301 ... Operation mode changer, 302 ... Power generation output setter, 303 ... Output change rate setter, 301-1, 301-2 ... switcher, 31 ... input device.

Claims (4)

The remote control signal of the pulse waveform sent from the remote control station is inputted, the pulse width is detected, it is judged whether or not the remote control signal is normally inputted, and the remote control signal that arrives next Remote control signal input processing means having a function of detecting the input of
An output change amount calculating means for calculating an output increase / decrease amount based on the pulse width detected by the remote control signal input processing means;
Output target value setting means for setting the power generation output target value in response to the output increase / decrease amount;
Output change rate calculating means for calculating the output change rate from the increase or decrease of the power generation output target value set by the output target value setting means;
Output command calculating means for calculating an output command based on the power generation output target value and the output change rate;
Boiler preceding control amount calculating means for calculating a boiler preceding control amount based on the output command output from the output command calculating means and the output change rate;
A set value of an air control system, a fuel control system, a feed water control system, and a steam turbine output control system is calculated by a boiler output command obtained by adding the output command and the boiler preceding control amount, and a boiler generated steam amount and steam A boiler control device that controls a turbine inflow steam amount.   The output change amount calculation means receives a notification that the next new remote control signal has arrived from the remote control signal input processing means, and calculates the output increase / decrease amount obtained based on the pulse width as the output target value setting means The boiler control device according to claim 1, wherein the boiler control device is notified.   3. The output change amount calculation unit has a function of clearing an output increase / decrease amount to 0 when receiving an input signal abnormality notification from the remote control signal input processing unit. Boiler control device. The boiler according to claim 1, wherein the output change rate calculation means has a function of limiting a rate of decrease of the output change rate in addition to a function of obtaining the output change rate by increasing or decreasing the power generation output target value. Control device.

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