JPS63253103A - Steam turbine control device - Google Patents

Abstract

PURPOSE:To simultaneously control speed and extraction pressure, or main steam pressure, and simultaneously control back pressure and a main steam system, or an extraction pressure system by providing a main steam control system and an extraction pressure system besides a speed control system. CONSTITUTION:A main steam pressure control signal calculated from a main steam pressure analog signal 21 is compared with a limiting value from a main steam pressure limiter 41 through a lower value precedence circuit 42, and a main steam pressure control signal (r) is outputted from the circuit 42. Then, an extraction pressure control signal (o) calculated from an extraction pressure signal 18 is compared with the signal (r) through a high value precedence circuit 43, and a higher value is outputted as a main steam pressure driving signal (s). On the other hand, a lower value is selected out of respective fixed conversion signals of a back pressure signal 19, a frequency analog signal (f), a signal from a load limiter 34, and a main steam control valve driving signal (t) is obtained. Adding the main steam control valve driving signal (t) to the main steam pressure driving signal (s), an oil cylinder 15 of a main steam control valve is driven. Amplifying the main steam pressure driving signal (s) by means of an amplifier 40, an oil cylinder 16 of an extraction control valve is driven.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a steam turbine control device, and particularly to a steam turbine control device applied to an extraction back pressure turbine or an extraction turbine applied to a private power plant. The present invention relates to a turbine control device.

(Prior Art) Recently, in private power generation plants, especially paper manufacturing plants, there have been an increasing number of power generation plants that effectively utilize steam generated from chemical recovery boilers and the like that utilize waste heat generated from the plants. Although the temperature of the steam generated by chemical recovery boilers is controlled, there is a first-order lag in the response of the pressure control system, which causes problems in the followability of steam turbine control. Instead, analog signals for boiler pressure control are generally taken into the steam turbine control device and left to the turbine control function, making turbine control even more complex.

Conventionally, when controlling such a steam turbine, the rotation speed control of the steam turbine generator was often performed in synchronization with the frequency of an external electronic system, and the steam turbine input steam pressure was controlled by the boiler. When trying to control the steam pressure emitted from the side, it was possible to do so only when the rotational speed was controlled.

FIG. 2 shows the functions of such a conventional steam turbine control device including a boiler and a steam turbine generator. 1 is a boiler, 2 is a main steam pressure detector, 3 is a main steam stop valve,
4 is a steam control valve that controls the steam flow rate to the high-pressure turbine 5; 6 is an extraction control valve that controls the turbine bleed pressure and the steam flow rate to the low-pressure turbine 7; 8 is a generator connected to the rotor of the steam turbine; 9 is a generator connected to the rotor of the steam turbine; The speed detection gear 10 is an electromagnetic pickup that detects the rotation speed of the speed detection gear 9 according to the rotation speed, and detects the turbine rotation speed as a frequency signal. 11 is a frequency/voltage converter (hereinafter referred to as F/V
converter) converts the detected frequency signal into a frequency analog signal f.

Reference numeral 12 denotes a bleed pressure detector that detects the bleed pressure from the high pressure turbine 5 and converts it into a bleed pressure signal 18. 13 is a back pressure detector that detects back pressure from the low pressure turbine 7, and back pressure signal 1
Convert to 9. The main steam pressure from the boiler 1 is detected by the main steam pressure detector 2 and converted into a main steam pressure analog signal 21 by the main steam pressure detector 14. The frequency analog signal f, the bleed pressure signal 18, the back pressure signal 19, and the main steam pressure analog signal lamp are input to the steam turbine control device 20. The steam control valve control signal 22 and the bleed air control valve control signal 23 are sent from the steam turbine control device 20 to the steam control valve oil cylinder 15. Controls the bleed air control valve oil cylinder 16 and drives the steam control valve and the bleed air control valve.

FIG. 3 is a block diagram of the steam turbine control device of FIG. 2.

The back pressure signal 19 is compared with a back pressure setting device 22 and a comparator 26,
The compared back pressure deviation signal g is made into a back pressure control signal i in accordance with the back pressure adjustment rate in the back pressure control circuit 27.

The bleed pressure signal 18 is compared with a bleed pressure setter 23 and a comparator 27 to output a bleed pressure deviation signal 30. The 6-frequency analog signal f is compared with a speed setter 24 and a comparator 31, and the compared speed deviation signal is input into the speed control circuit 31, and the speed deviation signal is converted into a speed control signal j that follows the speed regulation rate.
shall be. The main steam pressure analog signal 21 is compared with the main steam pressure setting device 25 by a comparator 32.

The compared main steam pressure deviation signal k is used as a main steam pressure control signal Ω in line with the main steam pressure adjustment rate in the main steam pressure control circuit 33.

The respective lower values of the back pressure signal i, speed control signal j, and main steam pressure control signal a are selectively calculated by a low value priority circuit (LVG) 28 and outputted as the speed control signal m. The speed control signal m is input to the main steam regulator control circuit 35, and the main steam regulator control circuit 35 compares the signal with the load limiter control circuit 34 and outputs a main steam pressure signal n with priority given to the lower value. . The adder 36 adds the main steam pressure signal n and the bleed pressure control signal 0, and the main steam pressure signal n and the bleed pressure control signal 0 are added together, and the amplifier 37 controls the main steam regulating valve. The signal is amplified to drive the main steam control valve oil cylinder 15 to control the main steam control valve 4 to control the amount of steam from the boiler 1 and drive and rotate the high pressure turbine.

On the other hand, the control to the bleed air adjustment valve is performed by applying the bleed pressure deviation signal 30 to the bleed pressure control circuit 38, converting it into a bleed pressure control signal in accordance with the bleed pressure adjustment rate, and performing a comparison calculation with the bleed pressure control circuit 39. The bleed pressure control deviation signal is input to the adder 39 as the bleed pressure control signal 0, and among the back pressure control signal i, speed control signal j, and main steam pressure control signal 0 given priority to the previous low value, the lower value is output. be done.

The speed control signal m is outputted by the adder 39, and the amplifier 40
The width of the bleed air adjustment valve control signal is increased by the bleed air adjustment valve oil cylinder 16.
control.

When controlling the operation of a steam turbine using such a steam turbine control device, it is not only necessary to synchronize the frequency of the external power system, but also when the steam turbine generator is required to operate independently within the station. There are cases.

(Problem to be solved by the invention) However, as shown in FIG. 3, the backpressure control signal i.

Since the speed control signal j and the main steam pressure control signal Ω are all connected to the low value priority circuit, one of the three control signals is extracted in order to give low value priority to one of the signals. Therefore, it is difficult to simultaneously perform speed control and main steam pressure control, back pressure control and speed control, or speed control and back pressure control.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a main steam pressure control system and a bleed pressure control system separately from a speed control system, so that speed control and bleed pressure or main steam pressure can be controlled simultaneously. , simultaneously controlling the back pressure control and the main steam system or extraction pressure control system,
It also performs optimal control of the turbine control system.

(Function) The present invention can perform main steam pressure control or back pressure control regardless of speed control and without affecting turbine control, and can perform main steam pressure control and back pressure control even during isolated operation within a station. Can be controlled.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention.
The same parts or functions as those in the figures are designated by the same reference numerals. The main steam pressure from the boiler 1 is detected by the main steam pressure detector, and the main steam pressure analog signal 21 which is converted from the main steam pressure into an electrical signal is taken out through the main steam pressure converter. Steam pressure detector 2
5 and the set value in the comparator 32, and the comparator 32
The main steam pressure deviation signal Q is converted into the main steam pressure control signal R calculated in accordance with the main steam pressure adjustment rate by the main steam pressure control circuit 48, and the limit value from the main steam pressure limiter 41 and the low value priority circuit are converted. The signals are compared at 42, and a signal with a lower value is output.

The low value main steam pressure control signal r outputted from the low value priority circuit 42 is controlled by the bleed pressure adjustment rate and the bleed pressure limiting circuit in the bleed pressure control circuit 38, and the calculated bleed pressure control signal 0 is set to a high value. The priority circuit 43 compares the bleed pressure control signal 0 and the main steam pressure control circuit signal, and the higher value is set as the main steam pressure drive signal S and is sent to the adder 39 as the back pressure signal 1.
9 and the frequency analog signal f, the steam control valve drive signal t having the lowest value is added through a constant circuit 45, amplified by an amplifier 40, and outputted as a bleed control valve control signal U. to drive the bleed air control valve oil cylinder 16.

Further, the back pressure signal 19 is a back pressure control signal i, and the speed control signal j of the frequency analog signal f is outputted as a low value by a low value priority circuit 46, and is output as a speed control signal m-1, and is used for load limiting. Load limit signal and speed control signal n-1 from device 34
The low value priority circuit 47 compares and calculates the lower value as the main steam control valve drive signal t, and the previous main steam pressure drive signal S is added through the constant circuit 44 in the adder 36, and the amplifier 3
7 to output the main steam regulating valve control signal V to drive the main steam regulating valve oil cylinder 15. [Effects of the Invention] As described above, in the configuration of the present invention, when the main steam pressure becomes high, the main steam pressure setting device Compared to the set value set in step 25, the deviation signal becomes larger on the main steam pressure side, which causes an open signal to be sent to the steam control valve oil cylinder and the main steam flow rate is output, causing the main steam pressure to decrease. . When the main steam pressure decreases, the bleed air adjustment valve oil cylinder 1 is controlled by the bleed air pressure signal 18 side.
The bleed control valve control signal to 6 is operated to the closing side, and the output increased by the high pressure turbine 5 is controlled to close the bleed control valve 5, thereby maintaining the main steam pressure of the high pressure turbine 5 and the low pressure turbine 7 at all times. Try to keep it constant.

Therefore, 1. By providing a main steam pressure control system, the present invention can always control the main steam pressure to a constant level regardless of speed control, back pressure control, and extraction pressure control, and stable turbine control can be performed. .

Furthermore, even when operating with the rotational frequency synchronized with an external power system, stable control can always be performed simultaneously using the back pressure signal and the main steam pressure signal, regardless of the frequency analog signal.

The steam turbine control device of the present invention not only has a circuit configuration using digital logic, but also has an analog circuit configuration that allows for stable extraction back pressure turbine control and makes it possible to effectively utilize the steam generated as a chemical recovery boiler. be.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing the function of a conventional boiler and a steam turbine generator, and Fig. 3 is a block diagram of a conventional steam tank control device. be. 1... Boiler 2... Main steam pressure detector 3
...Main steam stop valve 4...Steam control valve 5...
High pressure turbine 6, τ, extraction control valve 7...Low pressure turbine 8...Generator 9...Speed detection gear
10... Electromagnetic pickup 11... F/V converter 12... Bleed pressure detector 13... Back pressure detector 14... Main steam pressure converter 15... Steam control valve oil cylinder 16 ...Bleed air adjustment valve oil cylinder 17...Turbine rotation speed frequency signal 18...Bleed air pressure signal 19...Back pressure signal 20
... Steam turbine control device 20-1 ... Steam turbine control device 21 ... Main steam analog signal 22 ... Back pressure setting device 23 ... Extraction pressure setting device 24 ... Speed setting device 25. ... Main steam pressure setting device 27 ... Back pressure control circuit 31-1 ... Speed control circuit 38 ... Bleed pressure control circuit 42 ... Low value priority circuit 43 ... High value priority circuit 44 ...・Constant circuit 45...Constant circuit 48...Bleed pressure limiting circuit 48-1...Main steam pressure control circuit 47...Low value priority circuit 36...Adder 39・
... Adder 37 ... Multiplier 40 ... Multiplier agent Patent attorney Nori Chika Nori Yudo Ken Daishimaru Figure 2

Claims (1)

[Claims] In the steam turbine control device of the steam turbine control device of the steam turbine control device, which inputs the back pressure signal, the rotation speed analog signal, the extracted pressure signal, and the main steam pressure analog signal, the extracted pressure control signal from the extracted pressure signal is input. The main steam control signal of the main steam pressure analog signal is given priority to the high value, and the back pressure control signal and the speed control signal of the frequency analog signal are passed through the main steam control valve drive signal through the low value priority circuit. A steam turbine control device characterized in that the bleed air control valve and the main steam control valve are controlled by adding both control systems based on the main steam drive signal and the main steam control valve drive signal to a speed control circuit.