JP2008075529A - Device and method for stabilizing system frequency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly set and keep system frequency in a predetermined rated frequency range when automatic frequency control signal is input. <P>SOLUTION: A frequency adjustment load command operation part 20 of a plant integrated control device 15 operates frequency adjustment load command signal AFCr based on automatic frequency control signal AFC, and correction operation part 21 operates correction signal corresponding to fluctuation of generator output by the frequency adjustment load command signal AFCr. Correction frequency adjustment load command signal AFCa is calculated by adding correction signal on frequency adjustment load command signal AFCr, and is added on load command signal DPC and is output as output command value MWr of the generator 14. A boiler control device 16 controls a boiler to form steam corresponding to output command value MWr. A turbine control device 17 controls a turbine to set generator output MW to output command value MWr and controls system frequency in a predetermined range of rated frequency. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention calculates the output command value of the generator of the power plant based on the load command signal and the automatic frequency control signal from the power supply command device, and controls so that the generator output becomes the output command value. The present invention relates to a system frequency stabilization apparatus and method for controlling a frequency within a predetermined range of a rated frequency.

  Generally, the electric power system is operated so as to maintain a predetermined rated frequency (50 Hz or 60 Hz). When the load demand of the power system increases, the system frequency decreases, and when the load demand decreases, the system frequency increases. Therefore, the load command signal (DPC signal) from the power supply command device according to the power demand situation (for example, daily load curve) Is output, the generator output of the power plant is operated so as to maintain the load command signal, and the system frequency is maintained at a predetermined rated frequency.

  In addition, when the load suddenly increases or when a load interruption occurs, the system frequency cannot be maintained at the predetermined rated frequency by simply operating the generator output to the load command signal. An automatic frequency control signal (AFC signal) is output from the power supply command device, and the generator output is controlled based on the load command signal and the automatic frequency control signal to maintain the system frequency at a predetermined rated frequency.

  For example, in a thermal power plant, when the load command signal is changed from the power supply command device or when an automatic frequency control signal is newly input, the plant supervisory control device is based on the load command signal or the automatic frequency control signal. The output command value of the generator is calculated, and the fuel flow rate and feed water flow rate to the burner are controlled so that steam corresponding to the output command value is generated, and the output command value of the generator is output to the turbine controller To do. The turbine control device controls the steam control valve (CV) so that the generator output becomes the output command value.

Here, in the middle of the output of the CV opening command signal sent from the turbine controller, the actual machine operating characteristics (main steam pressure, temperature) and the turbine control system eigenvalues (regulating valve flow rate characteristics, slope adjustment rate) are corrected. A control system correction circuit is additionally provided to obtain an ideal CV opening characteristic and CV passage flow rate, to stabilize the slope adjustment rate and to improve load followability (for example, Patent Document 1). reference).
JP 2001-82105 A

  However, in the thing of patent document 1, although the control followability of the steam control valve CV after a turbine control apparatus is improved, it cannot respond to the lack of followability which a turbine control apparatus itself has. In particular, when the turbine control device is a mechanical governor MHC, a follow-up delay occurs due to the large friction of the governor mechanism, so even if the control follow-up performance of the steam control valve CV after the turbine control device is good, power generation The machine output cannot follow the generator output command value with good response. The follow-up delay of this mechanical governor MHC varies among thermal power plants.

  Therefore, the rise (fall) of the actual generator output due to the automatic frequency control signal (AFC signal) is delayed, and the system frequency may not be quickly maintained within the predetermined rated frequency range. Although the follow-up delay of the mechanical governor MHC can be improved by performing maintenance of the governor mechanism, it is expensive.

  Further, when the followability of the boiler is poor, it takes time to generate steam commensurate with the output command value, and it takes time until the actual generator output becomes the output command value. Even in this case, the system frequency cannot be quickly maintained within a predetermined rated frequency range.

  An object of the present invention is to provide a system frequency stabilization device and method capable of quickly maintaining a system frequency within a predetermined rated frequency range when an automatic frequency control signal is input.

  The system frequency stabilizing apparatus according to the first aspect of the present invention calculates the output command value of the generator of the power plant based on the load command signal and the automatic frequency control signal from the power supply command device, and the steam commensurate with the output command value. A plant control unit that controls the steam generator so that the steam generator generates, and a steam control valve that controls the generator output of the power plant to be an output command value from the plant control unit. In the system frequency stabilizing device including the turbine control device that controls the system frequency within a predetermined range of the rated frequency, the plant integrated control device calculates a frequency adjustment load command signal based on the automatic frequency control signal. A load command calculation unit for frequency adjustment, a correction calculation unit for calculating a correction signal according to a fluctuation amount of a generator output by the load command signal for frequency adjustment, and the correction operation An adder that adds the correction signal obtained by the unit to the frequency adjustment load command signal to obtain a correction frequency adjustment load command signal, and the correction frequency adjustment load command signal obtained by the adder And an adder that adds the signal to the output command value of the generator.

  The system frequency stabilization apparatus according to a second aspect of the present invention is the system frequency stabilizing device according to the first aspect, wherein the correction calculation unit includes a differentiation circuit for differentiating a fluctuation amount of the frequency adjustment load command signal, and the frequency adjustment load command. A proportional circuit that multiplies a signal by a predetermined gain, and a limiter that limits the added value of the differentiating circuit and the proportional circuit so as not to deviate from a predetermined limit value.

  A system frequency stabilization method according to a third aspect of the present invention calculates an output command value of a power plant generator based on a load command signal and an automatic frequency control signal from a power feeding command device, and generates a power generator output of the power plant. In the system frequency stabilization method for controlling the steam control valve so that the output command value is calculated and controlling the system frequency within a predetermined range of the rated frequency, the frequency is based on the automatic frequency control signal from the power supply command device. An adjustment load command signal is calculated, a correction signal corresponding to the fluctuation amount of the generator output due to the frequency adjustment load command signal is calculated, and this correction signal is added to the frequency adjustment load command signal to adjust the correction frequency. The load command signal is calculated, and the calculated correction frequency adjustment load command signal is added to the load command signal and output as an output command value of the generator.

  A system frequency stabilization method according to a fourth aspect of the present invention is the system frequency stabilizing method according to the third aspect, wherein the correction signal according to the amount of fluctuation in the generator output by the frequency adjustment load command signal is the frequency adjustment load command signal. Differentiating the fluctuation amount, multiplying the fluctuation amount of the frequency adjustment load command signal by a predetermined gain to obtain a proportional value, and obtaining the differential value and the proportional value so as not to deviate from the predetermined limit value. It is characterized by.

  According to the present invention, when there is an automatic frequency control signal from the power supply command device, a frequency adjustment load command signal is calculated based on the automatic frequency control signal, and the generator output by the frequency adjustment load command signal is calculated. A correction signal corresponding to the amount of fluctuation is calculated and added to the frequency adjustment load command signal to calculate a correction frequency adjustment load command signal having a larger absolute value. Then, the corrected frequency adjustment load command signal is further added to the load command signal to obtain the generator output command value, so that the generator output command value depends on the fluctuation amount of the generator output due to the frequency adjustment load command signal. Therefore, the followability of the actual generator output to the output command value is improved.

  FIG. 1 is a configuration diagram of a system frequency stabilization device according to an embodiment of the present invention. FIG. 1 shows a case where a system frequency stabilization device is applied to a conventional thermal power plant. The steam generated in the boiler 11 is supplied to the steam turbine 13 with the steam flow rate adjusted by a steam control valve (CV) 12 via a main steam stop valve (not shown). Then, the generator 14 is driven by the steam turbine 13 to obtain a predetermined generator output from the generator 14.

  The generator output MW of the generator 14 is controlled to become a load command signal DPC from a power supply command device (not shown). Further, an automatic frequency control signal AFC is output from the power supply command device, and the system frequency is controlled so as to maintain a range (rated frequency ± 0.2 Hz) within a predetermined rated frequency (50 Hz or 60 Hz). Further, the integrated value (time difference) of the daily frequency deviation is controlled to be within ± 15 seconds.

  A load command signal DPC and an automatic frequency control signal AFC from the power supply command device are input to the plant integrated control device 15. The plant integrated control device 15 calculates the output command value MWr of the generator of the thermal power plant based on the load command signal DPC and the automatic frequency control signal AFC, outputs the signal MWb to the boiler control device 16, and the turbine control device 17. To output a signal MWt.

  The main steam pressure control system 18 of the boiler control device 16 controls the fuel flow rate, the feed water flow rate, and the like to the burner so as to generate steam corresponding to the output command value MWr of the generator based on the signal MWb. On the other hand, the main steam flow rate control system 19 of the turbine controller 17 controls the steam control valve 12 based on the signal MWt so that the generator output MW becomes the output command value MWr. Thereby, it controls so that a system | strain frequency may maintain in the predetermined range of a rated frequency.

  The load command signal DPC from the power supply command device is input to the adder 22 of the plant overall control device 15 and is also input to the subtractor 25 and compared with the generator output MW to obtain the output deviation ΔP1. This output deviation ΔP1 corresponds to the generator output by the frequency adjustment load command signal AFCr.

  On the other hand, the automatic frequency control signal AFC from the power supply command device is input to the frequency adjustment load command calculation unit 20 of the plant overall control device 15. The frequency adjustment load command calculation unit 20 calculates a frequency adjustment load command signal AFCr based on the automatic frequency control signal AFC, and outputs it to the subtracter 26 and to the adder 27. The frequency adjustment load command signal AFCr is an output command value for compensating for fluctuations in the system frequency.

  The subtractor 26 calculates a difference ΔP2 between the frequency adjustment load command signal AFCr and the output deviation ΔP1, and outputs the difference ΔP2 to the correction calculation unit 21. This difference ΔP2 corresponds to the fluctuation amount of the generator output due to the frequency adjustment load command signal AFCr because the output deviation ΔP1 corresponds to the generator output due to the frequency adjustment load command signal AFCr.

  Based on the difference ΔP2 between the frequency adjustment load command signal AFCr from the subtractor 26 and the output deviation ΔP1, the correction calculation unit 21 corrects the correction signal a according to the amount of fluctuation in the generator output by the frequency adjustment load command signal AFCr. Is calculated. The correction signal a calculated by the correction calculation unit 21 is input to the adder 27, and is added to the frequency adjustment load command signal AFCr to obtain a corrected frequency adjustment load command signal AFCa that is larger than the frequency adjustment load command signal AFCr. obtain. The correction frequency adjusting load command signal AFCa obtained by the adder 27 is output to the adder 22.

  Here, the reason why the corrected frequency adjustment load command signal AFCa that is larger than the frequency adjustment load command signal AFCr is obtained is to make it possible to cope with the lack of followability of the boiler control device 16 and the turbine control device 17 itself. .

  The load command signal AFCa for correction frequency adjustment obtained by the adder 27 is further added to the load command signal DPC from the power supply command device by the adder 22, and as a generator output command value MWr, the boiler master 23 and the turbine master 24. Is output. The boiler master 23 outputs a signal MWb to the boiler control device 16 so that the boiler 11 generates steam commensurate with the output command value MWr of the generator. When the signal MWb is input, the main steam pressure control system 18 of the boiler control device 16 controls the fuel flow rate, feed water flow rate, and the like to the burner so as to generate steam corresponding to the output command value MWr of the generator.

  The turbine master 24 outputs a signal MWt to the turbine controller 17 so that the generator output MW becomes the output command value MWr for the turbine 13. When the signal MWt is input, the main steam flow control system 19 of the turbine controller controls the steam control valve 12 so that the generator output MW becomes the output command value MWr.

  FIG. 2 is a signal waveform diagram of each part of the system frequency stabilization apparatus according to the embodiment of the present invention. FIG. 2 shows a case where an automatic frequency control signal AFC for increasing the generator output MW is input. In this case, the AFC signal on the up side is described, but the signal on the down side is the same although the signal is in the opposite direction.

Now, it is assumed that the load command signal DPC from the power supply command device is the generator output MW0. In this state, it is assumed that the system frequency is reduced, and an increase signal of the automatic frequency control signal AFC for compensating for the decrease in the system frequency is input at time t1. Before time t1, the generator output MW of the generator is the generator output MW0 indicated by the load command signal DPC.

  When the automatic frequency control signal AFC is input at the time point t1, the frequency adjustment load command calculation unit 20 of the plant overall control device 15 performs, for example, proportional and integration calculations on the automatic frequency control signal AFC, and the frequency adjustment load A command signal AFCr is obtained. The frequency adjustment load command signal AFCr is an output command value for compensating for fluctuations in the system frequency. In FIG. 2, the load command signal AFCr is an output command value for increasing the generator output by ΔMW.

  Next, the correction calculation unit 21 calculates a correction signal a corresponding to the amount of fluctuation of the generator output due to the frequency adjustment load command signal. For example, the variation amount (ΔP2) of the frequency adjustment load command signal AFCr obtained by the subtractor 26 is differentiated by a differentiation circuit, and a proportional signal is multiplied by a gain to obtain a proportional signal, and these are added. A correction signal a corresponding to the fluctuation amount of the frequency adjustment load command signal AFCr is obtained.

  In this case, if the correction signal a is too large, the correction frequency adjustment load command signal AFCa may become too large. Therefore, a limiter is provided so that the output of the differentiation circuit and the output of the proportional circuit do not deviate from a predetermined limit value. Add restrictions.

  Then, the load command signal DCa for correction frequency adjustment is added to the load command signal DPC to calculate the output command value MWr of the generator. Based on this output command value MWr, the boiler control device 16 of the plant integrated control device 15 controls the pressure of the steam supplied to the turbine 13, and the turbine control device 17 controls the flow rate of the steam supplied to the turbine 13. Then, the generator output MW is controlled to become the output command value MWr.

  In this case, as shown in the generator output MW in FIG. 2, the generator output MW follows with a delay with respect to the output command value MWr from the delay in followability of the boiler 11 and the turbine control device 17 itself, and the time t2 The final target value (MW0 + ΔMW) is obtained. The curve MW ′ is the generator output when no correction is made to the frequency adjustment load command signal AFCr. In this case, the final target value (MW0 + ΔMW) is reached at time t3, which is considerably delayed.

  Here, the original output command value of the generator output MW is a value (DPC + AFCr) obtained by adding the load command signal DPC and the frequency adjustment load command signal AFCr, and the generator output MW is the original output command value ( It is desirable to change along (DPC + AFCr). When the output command value MWr is the original output command value (DPC + AFCr), the generator output is a curve MW ′.

  On the other hand, as in the embodiment of the present invention, correction is made to the frequency adjustment load command signal AFCr to obtain a corrected frequency adjustment load command signal AFCa, and the output command value MWr is set to (DPC + AFCa). Then, the generator output MW is changed along the original output command value (DPC + AFCr). Accordingly, the correction frequency adjustment load command signal AFCa is set so that the absolute value of the frequency adjustment load command signal AFCr is increased so that the actual generator output MW changes along the original output command value (DPC + AFCr). to correct.

  In this case, the generator output MW is prevented from exceeding the original output command value (DPC + AFCr). In addition, when correcting the frequency adjustment load command signal AFCr using a differentiation circuit and a proportional circuit, set the limiter setting value so that the generator output MW does not exceed the original output command value (DPC + AFCr). Will do. As a result, the generator output MW can output the generator output at an early stage only in the shaded portion with respect to the conventional curve MW ′. That is, the generator output MW can be controlled according to the automatic frequency control signal AFC with less follow-up delay. In the above description, the case where the present invention is applied to a thermal power plant has been described, but the present invention can also be applied to a turbine power generation facility having a governor mechanism.

According to the embodiment of the present invention, since the output command value of the generator is corrected to a large command value, the followability of the actual generator output to the output command value is improved. Further, since the follow-up performance of the generator output is improved, the frequency fluctuation is reduced, and as a result, the frequency correction amount by the automatic frequency control signal is reduced. Therefore, the fluctuation of the generator output by the generator is also reduced, and the correction operation by the automatic frequency control signal AFC, which is a disturbance for the power plant, is small and stable. As a result, the fuel efficiency of the power plant is improved, CO ₂ can be reduced, fluctuations in NOx and soot emissions can be reduced, and the operation at each operation end is stabilized, thereby extending the life.

The lineblock diagram of the system frequency stabilization device concerning an embodiment of the invention. The signal waveform diagram of each part of the system frequency stabilization apparatus concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Boiler, 12 ... Steam control valve, 13 ... Steam turbine, 14 ... Generator, 15 ... Plant control device, 16 ... Boiler control device, 17 ... Turbine control device, 18 ... Main steam pressure control system, 19 ... Main Steam flow control system, 20 ... load command calculation unit for frequency adjustment, 21 ... correction calculation unit, 22 ... adder, 23 ... boiler master, 24 ... turbine master, 25 ... subtractor, 26 ... subtractor, 27 ... adder

Claims (4)

  Based on the load command signal and the automatic frequency control signal from the power supply command device, the output command value of the generator of the power plant is calculated, and the steam generator is generated so that the steam generator generates steam corresponding to the output command value. A plant control unit for controlling the turbine, and a turbine control for controlling the steam control valve so that the generator output of the power plant becomes an output command value from the plant control unit and controlling the system frequency within a predetermined range of the rated frequency In the system frequency stabilization device, the plant overall control device includes: a frequency adjustment load command calculation unit that calculates a frequency adjustment load command signal based on the automatic frequency control signal; and the frequency adjustment load. A correction calculation unit that calculates a correction signal according to the amount of fluctuation of the generator output due to the command signal, and the correction signal obtained by the correction calculation unit An adder for adding a correction frequency adjustment load command signal by adding to the signal, and adding the correction frequency adjustment load command signal obtained by the adder to the load command signal and outputting the output command value as a generator A system frequency stabilizing device comprising an adder.   The correction calculation unit includes: a differentiation circuit that differentiates the amount of fluctuation of the frequency adjustment load command signal; a proportional circuit that multiplies the frequency adjustment load command signal by a predetermined gain; and an addition output of the differentiation circuit and the proportional circuit. The system frequency stabilizing device according to claim 1, further comprising a limiter that applies a limit so as not to deviate from a predetermined limit value.   Based on the load command signal and the automatic frequency control signal from the power supply command device, the output command value of the power plant generator is calculated, and the steam control valve is adjusted so that the power plant output of the power plant becomes the calculated output command value. In a system frequency stabilization method for controlling and controlling a system frequency within a predetermined range of a rated frequency, a frequency adjustment load command signal is calculated based on an automatic frequency control signal from the power supply command device, and the frequency adjustment load is calculated. A correction signal corresponding to the fluctuation amount of the generator output due to the command signal is calculated, the correction signal is added to the frequency adjustment load command signal to calculate a correction frequency adjustment load command signal, and the calculated correction frequency adjustment A system frequency stabilization method, comprising: adding a load command signal to the load command signal and outputting the output command value as a generator output command value.   The correction signal according to the fluctuation amount of the generator output by the frequency adjustment load command signal is obtained by differentiating the fluctuation amount of the frequency adjustment load command signal and adding a predetermined gain to the fluctuation amount of the frequency adjustment load command signal. 4. The system frequency stabilization method according to claim 3, wherein a proportional value is obtained by multiplication, and the differential value and the proportional value are obtained by adding a limit so as not to deviate from a predetermined limit value.

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