JPS6336003A - Turbine controller - Google Patents

Abstract

PURPOSE:To prevent a steam regulating valve from being throttled into at most steam flow flowing into a turbine and main steam pressure from excessive increase by controlling a load controlling signal with a high value priority circuit to prevent the turbine output from increase due to the load on a generator. CONSTITUTION:The rotational frequency signal 1 of a steam turbine is compared with the rotational frequency set value 2 by a substractor 3, and after the deviation signal is multiplied by a predetermined gain A through a speed set rate setter 4, a signal is added 5 from a load setter 6 to provide a load controlling signal applied to a high value priority circuit 23, where a generator output signal 20 is multiplied by gain C (<gain A) from a safety factor setter 21 to be compared with said load controlling signal and the signal having higher value is output to a low value priority circuit 7 as the load controlling signal. And in this low value priority circuit 7 said output is compared with main steam pressure deviation signal generated from a substractor 13 through a pressure regulation rate setter 14 to give a lower valve signal to a steam regulating valve as an opening commanding signal.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention is directed to a power generation plant in which the rotational speed of a steam turbine is controlled by a steam control valve. The present invention relates to a turbine control device that can prevent excessive increases in main steam pressure.

(Prior Art) In a thermal or nuclear power plant, the output of a generator is controlled by adjusting the amount of steam flowing into a steam turbine using a steam control valve.

FIG. 3 illustrates a control block diagram of the surface pressure control method that has been widely used in the past. The rotation speed signal 1 and the rotation speed setting value 2 of the steam turbine are sent to a subtracter 3 d3, and are compared and calculated. The turbine rotational speed deviation signal is multiplied by a predetermined gain A by the speed regulation rate setting device 4, and then added with the signal from the M setting device 6 in the adder 5, and then sent to the low value priority circuit 7 as a load control signal. is input.

On the other hand, the main steam pressure signal @11 and the main steam pressure set value 12 are subtracted by a subtractor 3, and the obtained deviation signal is sent to a pressure adjustment rate setting device 14 and multiplied by a predetermined gain B.
The signal is input to a low value priority circuit 7 and compared with the load control signal, and the lower signal is given to the steam control valve as an opening command signal.

In the turbine control device configured as described above, when the generator load is lost for some reason, the turbine load becomes larger than the generator load, so the steam turbine and generator are accelerated and the rotation speed increases. do. As a result, the rotational speed deviation signal increases to the negative side, the load control signal decreases, the steam control valve is throttled, and the turbine output is reduced.

In this way, a new steam control valve opening degree is determined so that the turbine output is balanced with the generator load.

In this way, when the generator load is lost, the amount of steam flowing into the turbine is adjusted by the action of the turbine control device, and eventually it stabilizes in a stable state that is balanced with the generator load, but the process In some cases, the main steam pressure increases due to an A-bar chute, etc., and the main steam relief valve or safety valve may operate.

Figure 4 shows the changes in main steam pressure, turbine rotational speed, and steam control valve opening when the generator load is reduced by half in a stepwise manner during rated operation (100%) of the power plant. The valve reaches balance when the amount of steam flowing into the steam turbine is halved, but since the closing speed is slow by one phase, the valve starts to open after it closes, and after overshooting and fully opening again, it opens again. The movement in the direction will be repeated.

During that time, the turbine speed and main steam pressure fluctuate greatly.
The main steam relief valve and safety valve operate to release excess steam into the atmosphere.

It would be possible to avoid the above-mentioned disadvantages by making the capacity of the turbine bypass valve approximately equal to that of the steam turbine, but this is actually impossible as it would significantly increase equipment costs.

(Problems to be Solved by the Invention) As mentioned above, in the conventional turbine control device, when the load of power generation plan 1- suddenly changes, the throttle valve of the steam control valve overshoots, the main steam pressure increases, and the main steam pressure increases. There were problems in that the relief valve or safety valve would operate, wasting energy, and it would take time to reach a stable state that corresponds to the load.

[Structure of Defense] (Means for Solving the Problems) The present invention has been made to eliminate the above-mentioned drawbacks in the background art. A signal corresponding to the output and a signal obtained by adding the rotation speed deviation signal to the signal from the load setting device are input to the high value priority circuit, and the output from this high value priority circuit is used as a load control signal and is output along with the main steam pressure deviation signal. The present invention is characterized by being configured such that the opening degree of the steam control valve is controlled by 1 with the opening command signal outputted from the low value priority circuit.

(Function) In the turbine control device of the present invention configured as described above, the load control fij is controlled by the high value priority circuit so that the turbine output does not increase due to the generator load. The turbine inflow steam flow rate is not reduced below the amount corresponding to the machine load, and therefore,
Excessive rise in main steam pressure is prevented.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In addition, in FIG. 1, the same parts as in FIG. 3 are given the same number 73, and only the differences will be explained.

In Fig. 1 (υ), the generator output signal 20 is given a predetermined gain C through the safety factor setter 21 with a gain slightly lower than the gain 1 of the speed regulation rate setter 4, and then is passed through the high value priority circuit. 22 (13) is compared with the signal from the adder 5, and the higher value is sent to the higher value priority circuit 2 as a load control signal.
2 to the low value priority circuit 7.

In the device of the present invention configured as described above, when the generator output is large, the steam regulating valve t will only reduce the steam flow rate to a level slightly smaller than the steam flow rate corresponding to the generator load, as shown in FIG. Even if the turbine load is suddenly halved, the steam control or opening will immediately reach 50% opening, and overshoe 1~ will hardly occur.
Turbine rotation speed and main steam pressure have little fluctuation due to the initial ripple, and transient fluctuations are significantly reduced.

[Effect of the invention 1 As described above, according to the present invention, it is possible to prevent the steam regulating valve from being throttled down more than necessary even in the event of load loss, so transient changes in the main steam pressure, etc. become gentle, and the health of the equipment is improved. In addition, even if the capacity of the turbine bypass valve is minimized, there is no need to release excess steam to the atmosphere, which has the effect of improving reliability and economy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the turbine control J device of the present invention, Fig. 2 is a graph showing its operation, Fig. 3 is a block diagram illustrating a conventional turbine control device, and Fig. 4 is a block diagram showing an example of the turbine control device of the present invention. This is a graph showing its operation. 3.13...Cylinder reducer 5...Adder Applicant: Toshiba Corporation Patent attorney Sasa Suyama - Figure 1 Figure 2

Claims (1)

[Claims] In the turbine control device of a power generation plant, a signal corresponding to the generator output signal and a signal obtained by adding the rotation speed deviation signal to the signal from the load setting device are input to a high value priority circuit, and the output from this high value priority circuit is A turbine characterized in that the load control signal is guided along with a main steam pressure deviation signal to a low value priority circuit, and the opening degree of the steam control valve is controlled by an opening command signal outputted from the low value priority circuit. Control device.