JPS6196105A - Speed regulator for steam turbine - Google Patents

Abstract

PURPOSE:To prevent a pressure adjusting loop from being operated unnecessarily by providing a control system to predict pressure variations after frequency variations are restored and for thereby limiting an instruction of the opening of a valve within a time constant of the pressure adjusting loop in the captioned speed regulator having a system frequency adjusting loop and the pressure adjusting loop. CONSTITUTION:The captioned device enters a deviation signal between a frequency set value signal from a frequency setting unit 10 and a frequency detection value signal 12 into a signal selection circuit 18 via a frequency adjusting unit 14. In addition, the signal selection circuit 18 enters a deviation signal between a pressure set value signal 28 and a pressure detection valve signal 30 of a boiler system via a pressure regulator 32. Moreover, a valve opening adjusting unit 24 issues a valve opening instruction value signal 26 in accordance with a deviation signal 20 and a valve opening detection value signal 22. Thereupon, a detection circuit 40 detects frequency variations from the above signal 12. A biass signal 46 read from a memory circuit 42 in conformity with said variation is delivered via an output circuit 44 and is compared with the above signal 12.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a speed governor for a steam turbine.

[Conventional technology]

As a conventional speed governor for a steam turbine, one configured as shown in FIG. 3 is known. In other words,
In FIG. 3, reference numeral 10 indicates a frequency setter;
The frequency set value signal set by the frequency setter 10 is compared with the frequency detection value signal 12 detected from the grid, and the deviation signal thereof is manually inputted to the frequency adjuster 14. Further, the output signal 16 of the frequency adjuster 14 has a frequency n,
', 5! , a valve opening setting value signal 20 via the stream circuit 18.
Here, the deviation signal is compared with the valve opening detection value signal 22 and input to the valve opening regulator 24, and the valve opening command value is output as the output signal 26 of the valve opening regulator 24. configured so that

In the speed governor configured in this way, when the system frequency fluctuates, that is, when the frequency detection value signal 12 fluctuates, the frequency adjuster 14 converts the fluctuation into a frequency setting value set by the frequency setter IO. A valve opening command value signal 26 is outputted to control the opening and closing of a turbine control valve (not shown) via a signal selection circuit 18 and a valve opening controller 24. Output. However, in a boiler system, the opening and closing of this control valve causes a disturbance, which appears as a fluctuation in the steam pressure at the turbine inlet.

- On the other hand, in addition to the above-mentioned frequency adjustment loop, the speed governor shown in FIG. A pressure regulation loop is provided which is configured to input the output signal of the pressure regulator 32 to the signal selection circuit 18 of the frequency regulation loop. However, pressure fluctuations in the boiler system detected by this pressure adjustment loop are detected as pressure detection value signals, and when the frequency fluctuates particularly large in the frequency adjustment loop described above, the pressure regulator 32 adjusts the frequency at the time of frequency fluctuation. A valve opening signal 34 in the opposite direction to the valve opening signal 16 outputted by the regulator 14 is supplied to the signal selection circuit 18 and the valve opening regulator 24 .

[Problem that the invention seeks to solve]

In this type of speed governor, the pressure regulator is used to adjust the pressure in the boiler system when the boiler system cannot follow changes in turbine output and cannot maintain the pressure at the set value, or when there is an abnormality in the boiler system. The operation of the pressure control loop relative to the frequency control loop as described above is unnecessary and undesirable, as it is intended to assist in the regulation function.

Therefore, an object of the present invention is to provide a speed governor that can prevent unnecessary operation of the pressure regulating loop described above.

[Means for solving problems]

Therefore, in the present invention, since the relationship between the fluctuation period t of the system frequency in the frequency adjustment loop and the time constant T of the pressure adjustment loop is generally t<T, the pressure in the boiler system after the frequency fluctuation is recovered is The turbine control valve is configured to predict fluctuations in pressure and control the turbine control valve in a direction to suppress pressure fluctuations.

That is, in the present invention, -ζ includes a frequency control loop that detects fluctuations in the system frequency and outputs a valve opening command to maintain the system frequency at a predetermined setting of 1, and a frequency control loop that detects pressure fluctuations in the boiler system. In a steam turbine speed governor equipped with a pressure control loop that outputs a valve opening command to maintain lever pressure at a predetermined set value, it detects frequency fluctuations when the system frequency fluctuates, and also detects the frequency fluctuations after the frequency fluctuations have recovered. The present invention is characterized by providing a control system that predicts pressure fluctuations in the boiler system and suppresses the valve opening command within the time constant of the pressure regulation loop.

In this case, the control system that suppresses the valve opening command includes a detection circuit that detects fluctuations in the system frequency, a detection signal of the frequency fluctuation detected by this detection circuit, and an output signal of the frequency adjuster of the frequency adjustment loop. Enter and write 1. a storage circuit configured to set the frequency of the frequency adjustment loop, and a reverse bias signal of the same amount as the output signal of the frequency adjuster of the frequency adjustment loop stored in the storage circuit upon recovery of the frequency fluctuation based on the period of the frequency fluctuation; and an output circuit that supplies the output terminal of the device.

[For production]

According to the present invention, since the time constant of pressure control is sufficiently large compared to the time of frequency fluctuation, when the turbine control valve is controlled to open or close due to a large fluctuation in system frequency, the frequency fluctuation can be recovered. By later supplying a valve opening signal opposite to the valve opening command at the time of fluctuation to the frequency adjustment loop within the time constant T of the pressure adjustment loop, fluctuations in the turbine inlet steam pressure can be effectively suppressed. .

[Embodiments of the invention]

Next, embodiments of a speed governor for a steam turbine according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block circuit diagram showing an embodiment of a speed governor according to the present invention. For convenience of explanation, the same reference numerals are given to the same components as those of the conventional speed governor shown in FIG. 3 described above, and detailed explanation thereof will be omitted.

That is, in this embodiment, a frequency fluctuation detection circuit 40 for detecting frequency fluctuation from the frequency detection value signal 12 detected for comparison with the frequency setting value signal set by the frequency setting device 10, Fluctuation detection circuit 4
a frequency adjuster 14 corresponding to the frequency fluctuation detected at o;
a storage circuit 42 for storing the output signal of the storage circuit 42, and a bias signal for adjusting the frequency setting value signal set by the frequency setting device 1o based on the signal stored in the storage circuit 42 in response to frequency fluctuations/movements. Output circuit 44 outputting 46
and.

The other circuit configuration is the same as that of the conventional speed governor shown in FIG.

Next, the operation of the device of this embodiment described above will be explained.

Now, let us assume that the system frequency has significantly decreased. When the system frequency decreases, the frequency regulator 14 outputs an opening command to further widen the valve opening in order to maintain the frequency at the set value. The amount Δfv of the open command at this time is stored in the storage circuit 42.

Therefore, when the frequency fluctuation is recovered, a negative bias signal 4 is applied from the memory circuit 42 via the output circuit 44 to reduce the frequency set value set by the frequency setter lO.
6 is output so that the frequency adjuster 14 outputs a close command of the same amount as the open command amount Δfν. In this case, the bias signal 46 has a time delay of about 3 to 4 times the time t of the frequency fluctuation because the closing command issued from the frequency adjuster 14 is too large and causes fluctuations in the direction of the turbine output.
ζ The amount is set to be the same as the amount △fv of the side order. −・
Generally, the time period for frequency fluctuation is several seconds + 5 degrees, and the time constant 1' of the pressure regulation loop is longer than this time t, so
The control in the frequency adjustment loop can be processed within the time constant of the pressure adjustment loop of 1, and the conventional pressure adjustment loop operation for the frequency adjustment loop can be prevented. Therefore, the relationship between the fluctuation characteristic of the system frequency in the present embodiment and the valve opening command characteristic I3 is as shown in FIG. 2.

In addition, in the present invention, 1) a time circuit is provided in the apparatus of the embodiment to measure the fluctuation time of the system frequency, and based on this measurement time, the frequency is adjusted within the range of the time constant T of pressure control of the boiler system. It is preferable to configure the bias signal 46 to calculate the optimum bias signal 46 for adjusting the frequency setting value in the adjustment loop.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention,
By detecting fluctuations in system frequency, predicting subsequent pressure fluctuations in the boiler system, and suppressing and outputting valve opening commands, the pressure regulation loop will not operate unnecessarily due to pressure fluctuations. Appropriate opening/closing control of the control valve of the turbine can be realized.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a steam turbine speed governor according to the present invention, FIG. 2 is a characteristic diagram showing control characteristics of the device of the present invention, and FIG. 3 is a diagram showing a conventional violet turbine. ,゛1. It is a block 1ljl road diagram showing an example of the configuration of a ζ1-speed device. 10. Frequency setter 12. ,,Frequency detection value signal 14, ,Frequency adjuster 16. ,,Output signal (valve opening degree) IFL,,Signal selection circuit 20. ,,valve opening setting value signal 22),,valve opening detection value signal 24. ,,Valve opening regulator 26, ,Output signal (valve opening command value) 2B, ,Pressure set value signal 30. ,, Pressure detection value signal 32),, Pressure regulator 40. , , frequency fluctuation detection circuit 42) , , memory circuit 44. ,,output circuit 4
6,,,bias signal FIG,I FIG,2

Claims (3)

[Claims] (1) A frequency control loop that detects fluctuations in the system frequency and outputs a valve opening command to maintain the system frequency at a predetermined set value, and a frequency control loop that detects pressure fluctuations in the boiler system and sets this pressure to a predetermined value. In a steam turbine speed governor equipped with a pressure control loop that outputs a valve opening command to maintain the same value, the system detects frequency fluctuations when the system frequency fluctuates, and also detects pressure fluctuations in the boiler system after the frequency fluctuation has recovered. A speed governor for a steam turbine, comprising a control system that predicts and suppresses a valve opening command within a time constant of a pressure regulation loop. (2) In the steam turbine governor according to claim 1, the control system that suppresses the valve opening command includes a detection circuit that detects fluctuations in system frequency, and a frequency detected by this detection circuit. a storage circuit for inputting and storing a fluctuation detection signal and an output signal of a frequency adjuster of the frequency adjustment loop; and a storage circuit for inputting and storing a fluctuation detection signal and an output signal of a frequency adjuster of the frequency adjustment loop; A speed governor for a steam turbine, comprising an output circuit that supplies a reverse bias signal of the same amount as the output signal of a frequency adjuster to the output end of a frequency setter of a frequency adjustment loop. (3) In the steam turbine speed governor according to claim 1 or 2, the control system for suppressing the valve opening command is provided with a timing circuit that measures the time during which the system frequency fluctuates, A speed governor for a steam turbine configured to calculate an appropriate reverse bias signal after recovery from frequency fluctuations.