JP3542174B2 - Automatic load control device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an automatic load control device having a stable turbine load following capability when a load changes.
[0002]
[Prior art]
Generally, in a thermal or nuclear power generation system, as shown in FIG. 5, a turbine 2 having a generator 1 and a boiler 4 are connected, and a regulating valve 3 is provided therebetween.
[0003]
The control valve 3 controls the flow rate of main steam flowing into the turbine 2 from the boiler 4 and is connected to the governor 8 via a cam mechanism and a hydraulic mechanism.
[0004]
The governor 8 is driven by a governor motor 9, and the position at that time is detected by a governor position detector 10.
[0005]
The power generation system includes a deviation calculator 13 for calculating a deviation between a load setter 12 for determining an opening command of the regulator valve 3 driven by the governor 8 and a generator output detector 21, and further a proportional integration. The proportional-plus-integral calculator 15 for performing the calculation and the automatic load control device 11 incorporate a control valve steam flow characteristic correction function generator 17, a control valve steam flow characteristic correction inverse function generator 18, and a comparison detection amplifier 16. . Here, the function generator 17 and the inverse function generator 18 are for performing stable load following with a constant loop control gain of the turbine output ratio characteristic with respect to the control valve stroke in FIG. The control valve is usually a combination valve of 1 to 4 valves, and controls the steam flow rate by increasing or decreasing or switching the number of open valves. The main steam flow ratio to the stroke, that is, the turbine output ratio has a non-linear characteristic. In the example, at point A, the change in the output is small and the value suddenly becomes large because it is the switching point of the valve.
[0006]
Therefore, the output of the proportional integrator 15 is used by the control valve steam flow characteristic correction function generator 17 to keep the turbine output change with respect to the apparent control valve opening command.
[0007]
As related to the above-mentioned prior art, for example, Japanese Patent Laid-Open Publication No. HEI 1-125503 discloses a content of estimating nonlinear characteristics of a control valve and correcting a valve opening command.
[0008]
[Problems to be solved by the invention]
By the way, the output Pg of the turbine generator is
Pg = kw · Δi
Where: k: constant w: main steam flow rate (excluding turbine bleed air flow rate)
Δi: It can be expressed by a heat head enthalpy, and the heat head enthalpy Δi is influenced by the degree of vacuum of the condenser.
[0009]
The actual control of the steam flow characteristics of the control valve is performed by the governor (synchronous spindle) position detector 10 and the generator output detector 21 by driving the governor motor 9. The accuracy is lacking due to the influence on the generator output due to the impact, the displacement of the cam mechanism due to the periodic inspection and disassembly every year, and the influence of the displacement of the hydraulic mechanism on the governor (synchronous spindle) position. It becomes necessary and extremely complicated.
[0010]
As shown in FIG. 3, the precision of the generator output (MW) with respect to the load command (MWD) deteriorates due to the lack of accuracy and the deviation of the characteristics, and hunting occurs near the point A passing.
[0011]
An object of the present invention has been made in view of such circumstances, and it is an object of the present invention to provide an automatic load control device having a stable turbine load following capability when a load changes.
[0014]
[Means for Solving the Problems]
The automatic load control device according to the first aspect of the present invention provides a load command for a generator output and a difference command between the generator output and an opening command for a regulator valve that adjusts a main steam flow supplied to the turbine by a calculation of a proportional integrator. A governor position detector for detecting the position of the governor that adjusts the opening of the control valve by using the opening degree command signal, and determining the governor position based on the detection signal from the governor position detector. In the automatic load control device to control,
A gain correction function generator that outputs a gain correction signal of the proportional integrator based on the detection signal of the governor position detector; and a deviation between a load command of the generator output and the generator output, the gain correction function A multiplier that multiplies the gain correction signal output by the generator, and a correction unit that corrects the gain of the proportional integrator based on the governor position,
The gain correction function generator outputs a correction signal such that the gain of the proportional integrator becomes lower than usual when the switching of the control valve is performed.
[0016]
[Action]
In the automatic load control device or the power generation system having the above-described configuration, even when the generator load hunts due to the non-linear characteristic of the control valve when the load changes, the control gain is easily corrected and the stable turbine load followability is maintained. In particular, when the control valve is switched, the gain of the proportional integrator is made lower than usual, so that excessive overshoot and undershoot accompanying the load change that occurs when the control valve is switched. Can be reduced.
[0017]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 shows a configuration of an embodiment of a power generation system to which an automatic load control device according to the present invention is applied. As shown in FIG. 1, a feature of the present invention is that a multiplier 14 and a gain correction value function generator 19 are provided in an automatic load control device 11, and the gain of a proportional-integral calculator 15 is provided by the correction value function generator 19. The correction is made and the steam flow characteristic correction function generators 17 and 18 of the control valve are stopped. The other configuration is the same as that of the conventional example shown in FIG. In the above configuration, the governor (synchronous main shaft) position detector 10 detects a signal corresponding to the control valve stroke and outputs the detected signal to the correction value function generator 19.
[0019]
The correction value function generator 19 outputs a proportional integrator (control loop) gain correction signal to the multiplier 14 based on the detection signal from the governor (synchronous spindle) position detector 10.
[0020]
Further, the calculator 14 takes in the correction signal from the correction value function generator 19 and the deviation signal from the deviation calculator 13 which performs the deviation calculation based on the signals from the load setter 12 and the generator output detector 21. , And outputs the result to the comparison detection amplifier 16. In the present embodiment, the multiplier 14, the correction value function generator 19, and the governor (synchronous spindle) position detector 10 constitute a correcting means.
[0021]
According to the automatic load control device configured as described above, the optimal setting of the gain of the control loop can be performed in accordance with the change in the steam flow characteristic of the control valve. The principle will be described below.
[0022]
FIG. 6 is a characteristic diagram of gain correction of the proportional integrator (control loop) with respect to the governor (synchronous main shaft) position. As described in the characteristic table of the control valve speed relay stroke to the turbine output ratio in FIG. 2, near the switching point A of the control valve, the effect of suppressing the hunting at the time of load change by lowering the control gain for changing the turbine output. is there.
[0023]
In this operation, the load is set by the load setter 12, and the control is performed by the deviation calculator 13 and the proportional-integral calculator 15 so that the feedback signal from the generator output detector 21 matches this target value. The control method is used. However, the optimal control gain of this proportional-integral calculator is determined by an average value from the gain (slope) of the output ratio to the turbine and the response characteristics in the characteristic table of FIG. Where the output ratio gain (slope) fluctuates rapidly, the gain of the deviation signal ΔMW from the deviation calculator 13 must be corrected by the multiplier 14 to a lower value. The correction gain of the multiplier is set by a gain correction function generator 19 to which a signal from the governor position detector + valve reduction speed relay stroke 10 is input. The configuration and contents of the gain correction means are such that the deviation signal ΔMW from the deviation calculator 13 and the correction signal output K from the gain correction function generator 19 are multiplied by the multiplier 14 to obtain a corrected deviation signal K · ΔMW. by. This signal is proportionally integrated by the proportional-integral calculator 15 to obtain a corrected governor position (open / close valve opening) command (KP · K · ΔMW + ∫K · ΔMWdt / TI). FIG. 4 shows this effect in a time chart, and it can be seen that the effect is improved as compared with FIG. 3 of the related art. This correcting means suppresses overshoot and undershoot of the control signal for controlling the opening of the steam control valve as shown in FIG. When the setting is changed, overshoot and undershoot always occur. The amounts of the overshoot and the undershoot are determined by the deviation signal ΔMW and the proportional gain setting of the proportional-integral calculator, ie, the integral gain (time) setting. For the set value, the optimum solution is experimentally determined by the ZIEGLER NICHOLS from the response to the step change. However, it is difficult to perform this in a detailed operation range with a real machine.
[0024]
Therefore, paying attention to the deviation signal ΔMW, the overshoot and the undershoot are expected to be large where the gain (gradient) with respect to the turbine output ratio sharply fluctuates as in the vicinity of the point A as described above. The deviation signal K · ΔMW after setting and apparent correction is suppressed, and overshoot and undershoot are suppressed. Even if the non-linear characteristics of the control valve cannot be measured accurately, or if the characteristics deviate due to aging due to periodic inspections every year, the hunting situation is checked and the gain of the governor (synchronous spindle) position is easily determined online. Can be adjusted.
[0025]
【The invention's effect】
As described above, according to the present invention, since the control loop gain is configured to be corrected based on the governor (synchronous main shaft) position signal, the nonlinear characteristics of the control valve cannot be accurately grasped. If the characteristics deviate due to aging, it is easy to adjust and stable turbine load following performance can be secured.Especially, when the control valve is switched, the gain of the proportional integrator is usually adjusted. Since it is lower than the time, it is possible to reduce excessive overshoot and undershoot accompanying a load change that occurs when the control valve is switched.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one embodiment of a power generation system to which an automatic load control device according to the present invention is applied.
2 is a characteristic diagram showing an opening degree characteristic, a main steam amount ratio, and a turbine output ratio characteristic of a combination control valve with respect to a control valve speed relay stroke of the automatic load control device illustrated in FIG. 1;
FIG. 3 is a characteristic diagram showing a relationship between a generator command (MW) and a load command (MWD) of the conventional automatic load control device shown in FIG. 5;
FIG. 4 is a characteristic diagram showing a relationship of a generator output (MW) with respect to a load command (MWD) of the automatic load control device of the present invention shown in FIG. 1;
FIG. 5 is a configuration diagram showing a power generation system provided with a conventional automatic load control device.
FIG. 6 is a characteristic diagram showing a relationship between a governor (synchronous main shaft) position and a gain correction of a proportional integrator in the automatic load control device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Turbine, 3 ... Regulator valve, 4 ... Boiler, 8 ... Governor, 9 ... Governor motor, 10 ... Governor position detector, 11 ... Automatic load control device, 12 ... Load setting device, 13 ... Deviation calculation , 14 ... Multiplier, 15 ... Proportional-integral calculator, 16 ... Comparison detection amplifier, 17 ... Regulator valve steam flow characteristic correction function generator, 18 ... Regulator valve steam flow characteristic correction inverse function generator, 19 ... Gain correction function Generator 21, generator output detector.

Claims (1)

The load command of the generator output and the deviation between the generator output are calculated by a proportional integrator to determine the opening command of the regulator valve for adjusting the main steam flow supplied to the turbine, and using this opening command signal, An automatic load control device that has a governor position detector that detects a position of a governor that adjusts the opening degree of the control valve, and controls the governor position based on a detection signal from the governor position detector,
A gain correction function generator that outputs a gain correction signal of the proportional integrator based on the detection signal of the governor position detector; and a deviation between a load command of the generator output and the generator output, the gain correction function A multiplier that multiplies the gain correction signal output by the generator, and a correction unit that corrects the gain of the proportional integrator based on the governor position,
The gain correction function generator, automatic characterized by time to, the gain of the proportional integrator is configured to output a correction signal as normally is lower than when the switching of the control valve is being performed Load control device .

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