JPH0392505A - Control device for steam turbine - Google Patents

Abstract

PURPOSE:To enhance the effect of restricting the variance in the system frequency in the case of change in the steam turbine revolution by changing the speed adjustment rate according to the actual revolution or to the deviation of the actual revolution relative to a preset value. CONSTITUTION:Steam with its flow rate adjusted with a steam control valve 4 enters a steam turbine 1 to rotate an impeller and to drive a generator 2. The revolution of the steam turbine 1 is detected with a detector 3. The detected value is compared at a subtractor 5 with preset speed/load values and taken out as revolution deviation. At the same time, the revolution deviation is amplified with an amplifier 6 to finally change the opening of the steam control valve 4. In this case, the speed adjustment rate which determines the amplification factor of an amplifier 6 is changed with a function generator 7 with the turbine revolution as an input. This increases the output variance width of the steam turbine 1 relative to the system frequency variance so that the effect of restricting the frequency variance is enhanced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a steam turbine control device, and in particular, to a control device for a steam turbine, which controls the speed regulation rate of a steam turbine when the system frequency fluctuation greatly deviates from the rated value. The present invention relates to a steam turbine control device suitable for suppressing system frequency fluctuations by changing the system frequency.

This will be explained with reference to the figure. Steam from a steam generator (not shown) has its flow rate adjusted by a steam control valve 4, flows into the steam turbine 1, expands, and rotates an impeller. The steam turbine 1 is connected to a generator 2, and the thermal energy of the steam is finally extracted from the generator 2 as electrical energy. During normal operation, the rotation speed of the steam turbine 1 is synchronized with the grid frequency due to the synchronization force generated by the generator 2 being parallel to the power grid, for example, in a two-pole generator at a grid frequency of 50 Hz. 3, OOOrpm. The turbine rotation speed is detected by the detector 3, compared with the speed/load setting value by the subtractor 5, and taken out as the rotation speed deviation X. The rotational speed deviation or is amplified to a preset magnification by the amplifier 6,
RFinally, the opening degree of the steam control valve 4 is changed. amplifier 6
The amplification factor is the reciprocal of the speed regulation rate R (generally about 5%).

In a steam turbine equipped with such a control device, the response when the system frequency fluctuates during system parallel operation is as shown in the following example.

Example C-1] When the system frequency changes from 50Hz to 49Hz while the turbine is operating at 50% load and 3,000 rpm, i) Rotation speed deviation or (50-49)/50 = + 2% ii) Amplifier output is (+2%)X(175%)=+40% Therefore, in this case, the steam control valve 4 is opened in the direction of increasing the turbine load by 40%. Example C-2] When the system frequency increases from 50 Hz to 50.5 Hz while the turbine is operating at 50% load and 3.00 rpm, i) The rotation speed deviation X is (50-50.5)/50 = -
1%5) The amplifier output is (-1%) x (175%) = -2
0%, that is, in this case, the steam control valve 4 is closed in the direction of reducing the turbine load by 20%.

(Problems to be Solved by the Invention) As shown in the two examples above, the steam turbine control device operates in the direction of compensating for system frequency fluctuations, but its characteristics depend on the magnitude of system frequency fluctuations. Regardless, it is determined by the speed adjustment rate. For this reason, even when the system frequency fluctuation is large, the proportion of compensation operation by the speed governor is small, and there is a problem in that the steam turbine 1 cannot fully demonstrate its capabilities.

On the other hand, from the point of view of electricity consumers, the system frequency remains constant and does not deviate from the rated value under any circumstances.Also, even when the turbine generator 2 is closed, it is continuously operated at a rotation speed that is outside the rated rotation speed. If so, damage to the equipment may occur.
It is undesirable to operate at a speed that is outside the rated speed, and it is naturally necessary to maintain the system frequency at the rated value.

The present invention is intended to meet the above-mentioned needs, and aims to provide a steam turbine control device that enhances the effect of suppressing system frequency fluctuations.6 [Configuration of the Invention] (Means for Solving the Problems) ) In order to achieve the above object, the present invention adjusts the opening degree of the steam control valve by multiplying the deviation between the steam turbine rotation speed detected by the rotation speed detector and the speed/load setting value by the reciprocal of the speed regulation rate. A control device for a steam turbine, characterized by comprising means for changing the speed regulation rate according to the actual rotation speed or the deviation from the actual rotation speed set value when the steam turbine rotation speed fluctuates from a set value. It is something. (Function) With this structure, as the frequency deviation increases, the range of change in the turbine output increases, the amount of compensation for system frequency fluctuation can be increased, and the suppression effect thereof can be increased.

(Example) An example of the present invention will be described below with reference to the attached drawings. FIG. 1 is a diagram showing an embodiment of a steam turbine control device according to the present invention. Here, the same parts as in the conventional example shown in Fig. 6 are given the same reference numerals and their explanation will be omitted. In FIG. 1, in this embodiment, the amplification factor of amplifier '6 is 1/
Is the speed regulation rate R that determines R the turbine times? It is configured to vary by a function generator 7 which receives a number as input.

An example of the characteristics of the function generator 7 is shown in FIG. According to this example, while the turbine speed is around the rated value (100%), the speed regulation rate is 5%, but when the rotation speed is below 100-α% or above 100+α%, the regulation rate is 5%
By making it smaller than , the effect of suppressing system frequency fluctuations is enhanced. Another example of the characteristics of the function generator 7 is shown in FIG.

In this example, the speed adjustment rate near the rated value is set to 5%, which is the same as the example above, but by changing the speed adjustment rate in a curved manner in areas outside of that range, sudden changes in the response characteristics can be avoided. This has been taken into consideration.

FIG. 4 shows a second embodiment of the invention. In this example, the rotational speed deviation X is used as an input to the function generator 7. The characteristics of the function generator 7 in this case are the same as those shown in FIGS. 2 and '3.

However, in this case, the horizontal axis in FIGS. 2 and 3 is the rotation speed deviation, and the 100% position is read as ■ zero deviation.

FIG. 5 shows a third embodiment. This embodiment corresponds to Fig. 1, but instead of using the amplifier 6 in Fig. 1, the output of the function generator 8 is directly applied to the output of the function generator 8, so that the multiplier 9 is used. It is composed of Similarly, the embodiment shown in FIG. 4 can also be handled by combining the function generator 8 and the multiplier 9.

In any of these cases, the same effects as in the first and second embodiments can be obtained.

〔Effect of the invention〕

As explained above, according to the steam turbine control device according to the present invention, even if the system frequency fluctuates during system parallel operation of steam turbines, the width of the output change of the steam turbine is increased, thereby suppressing frequency fluctuations. It becomes possible to increase the

[Brief explanation of drawings]

Fig. 1 is a functional block diagram showing an embodiment of the steam turbine control device according to the present invention, Fig. 2 is a graph showing the output characteristics of the function generator used in the present invention, and Fig. 3 is the output of the function generator. Graphs showing other examples of characteristics, FIGS. 4 and 5 are functional block diagrams showing other different embodiments of the present invention, and FIG. 6 is a functional block diagram showing an example of a conventional control device.

Claims (1)

[Claims] The steam turbine rotation speed detected by the rotation speed detector,
In a steam turbine control device that adjusts the opening degree of the steam control valve by multiplying the deviation from the speed/load setting value by the reciprocal of the speed regulation rate, when the steam turbine rotation speed fluctuates from the set value, the actual rotation speed or A control device for a steam turbine, comprising means for changing a speed regulation rate according to a deviation between an actual rotation speed and a set value.