JP2818322B2 - Steam turbine controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine control device in a steam turbine plant, and more particularly to a steam turbine control device in which a steam control valve is controlled by a position signal from a speed control unit in a mechanical hydraulic control device. It relates to improvement of the device.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a schematic configuration of a conventional steam turbine control device having a mechanical hydraulic control device and an electric cam control device. The steam generated by a steam generator 1 is a main steam stop valve. 2 and the steam control valves 3a and 3b are supplied to the turbine 4, where the turbine is rotated to generate an output, and the output drives the generator 5 to obtain the generated power.

By the way, the main steam stop valve 2 is connected in parallel with a main steam stop valve bypass valve 2a having a small steam capacity of about 10% or more of the total steam amount. The main steam stop valve 2 and the main steam stop valve bypass valve 2a are mechanically linked,
When the main steam stop valve bypass valve 2a is less than fully open, the main steam stop valve 2 is controlled to be opened and closed via a motor 11 operated by a turbine start / load control device 10 and a valve drive device 12 driven by the motor 11. Is fully closed,
The main steam stop valve 2 is opened when the main steam stop valve bypass valve 2a is fully opened or more. Although only two steam control valves are shown in the figure, an appropriate number of steam control valves are generally used according to the steam capacity.

The opening and closing of the steam control valves 3a and 3b is controlled by a mechanical hydraulic control device 13 and an electric cam control device 14. In the mechanical hydraulic control device 13, mechanical devices such as an electric motor, a mechanical lever, a link, a cam and the like are used. Transmission and calculation by the system and hydraulic pressure are performed.

That is, a control signal from the turbine / load control device 10 is applied to a synchronous setting motor 15 and a load limiting motor 16, and the synchronous setter 17 and the load limiter 18 are operated by the motors 15 and 16, respectively. ,
Synchronization setting and load limitation are performed. The synchronization setting unit 17 sets the speed and load of the turbine. When the generator 5 is not in parallel with the power system, the turbine speed can be set within a range of approximately 95% to 107% of the rated speed. In the synchronous operation state in parallel with the system, the turbine load is set.

Thus, the setting signal P ₁ of the synchronization setting device 17
Is input to an adder 20 where the turbine speed detector 1
Is the compared with the turbine speed signal P ₂ detected by 9, the required turbine steam flow deviation signal P ₃ is corresponding to the deviation is input to the coefficient unit 21 is obtained. Then, the output signal P ₄ from the coefficient unit 21 is input to the low value selector 22.

On the other hand, the setting signal P ₅ of the load limiter 18 is also input to the low value selector 22, the signal P and the output signal P ₄ lower of the setting signal P ₅ of the load limiter 18 from the coefficient multiplier 21 ₆ is selected and the speed relay 23 for signal transmission is selected.
Is input to Here, when greater than the set signal P ₅ of the signal P ₄ a load limiter 18 by increasing the set value of the synchronous setting unit 17, a constant turbine output irrespective of the turbine speed in a state of P 6 ₌ P ₅ it can be, also when the state of the P ₅ ≧ P ₄ is set larger the load limit setting signal P ₅ to the contrary, the turbine governor state becomes P 6 ₌ P _4.

Accordingly, the output P ₇ from the speed relay 23 is input to a position detector 24 for detecting the position of the speed relay, and the detection signal P ₈ is input to the electric cam control device 14.

[0009] Electrical cam control device 14 is constituted by an electrical circuit, the speed relay position signal P ₈ each steam control valve 3a, the steam control valve controller 25a for 3b, is input to 25b, control the steam control valve The steam control valve opening command signals v ₁ , v ₂ are output from the heaters 25 a, 25 _b , and the respective valve driving devices 26 a, 2 are output by the steam control valve opening command signals v ₁ , v 2.
The opening of each steam control valve 3a, 3b is adjusted via 6b.

Since the relationship between the opening of the steam control valve and the steam flow rate is non-linear due to the structure of the valve body, a compensator 27a for compensating the non-linearity in order to perform linear control on the command value. , 27b, 28a, 28b are provided in the respective steam control valve controllers 25a, 25b as shown in FIG.

In general, during normal load operation, the plurality of steam control valves 3a and 3b are arranged such that, for example, the first valve is fully opened before the second valve is opened, and when the second valve is fully opened, the next valve is opened. When the turbine output is low, only the first steam control valve is opened and the rest is fully closed. However, if such a state continues for a long time, vibration of the steam control valve main body is induced and noise is generated. Further, steam cooled by the throttle of one steam control valve flows into the turbine, and the temperature of the turbine casing locally changes, causing thermal stress, and deformation of the casing may lead to an increase in turbine shaft vibration. Therefore, when the turbine is operated for a long time at a low output, a method of simultaneously opening or closing a plurality of steam control valves is adopted.

Thus, in FIG. 5, the compensators 27a,
The steam control valves 3a, 3b are simultaneously opened and closed by 28a, and the steam control valves 3a, 3b are controlled by compensators 27b, 28b.
3b is sequentially controlled to open and close. Then, the compensators 27a,
Whether each of the selectors 29a or the compensators 27b and 28b is used is determined by a selector command signal (not shown).
a, 29b, and the selector 29
a, 29 b via the steam control valve opening command signals v ₁ , v ₂
Is output.

In such a turbine control device, there are a method of starting the turbine by the mechanical hydraulic control device and a method of starting the turbine by the electric motor 11.

In order to start the turbine with the mechanical hydraulic control device, there is a method of operating the synchronization setting motor 15 and the load limiting motor 16, and the speed adjustment range of the synchronization setting motor 15 is the rated speed. Since it is near ± several%, control from zero speed is not possible. Thus, the synchronization setting motor 15 is set to maximum or slow limit, it is also possible to turbine start by selecting a load limit setting value P ₅ by the operation of the load limiting electric motor 16.
However, the steam flow required to bring the turbine to rated speed is a few percent of the total steam flow since the generator is not connected to the power system and the turbine load is zero. Therefore, several percent of this is controlled by the load limiting motor 16 that can set the total steam flow rate, and it is impossible to obtain high speed control accuracy.

On the other hand, when the turbine is started by controlling the opening of the main steam stop valve bypass valve 2a by the electric motor 11, the electric motor 11 can be adjusted in a narrow range of up to more than ten percent of the total steam flow. There is no problem of speed control accuracy.

That is, when the turbine is started by the electric motor 11, the synchronous setter 17 and the load limiter 18 are set to the maximum, each steam control valve is fully opened, and the opening degree of the main steam stop valve bypass valve 2a is adjusted by the electric motor. Control from zero by 11;
This is performed by adjusting the flow rate of steam passing through the main steam stop valve bypass valve 2a. And after the turbine reaches the rated speed, put the generator in parallel with the power system,
Thereafter, the load operation state is synchronized with the power system.

Before reaching the maximum adjustment range of the motor 11, the synchronization setting motor 15 and the load limiting motor 16
, The steam control valve is squeezed from the fully open point, and when the steam control valve is squeezed to the steam flow rate flowing to the turbine at that time, the synchronous setting motor 15 and the load limiting motor 1
6, the main steam stop valve bypass valve 2a is fully opened and the main steam stop valve 2 is fully opened, and the turbine control is shifted from the motor 11 to the control of the synchronization setting motor 15 and the like.
The subsequent load operation is performed.

[0018]

As described above, the conventional turbine is started by operating the motor for operating the main steam stop valve bypass valve. The control of this motor is performed by the motor and the mechanical system connected to the motor. Since it is configured, there is a problem that the speed controllability becomes unstable due to the play of the mechanical system or the transmission delay. Further, it is difficult to maintain the mechanical system and adjust the control device to eliminate such a problem. In addition, the motor for operating the main steam stop valve bypass valve is an integrator on the transfer function, and the turbine body is also an integral system, so the overall control system is a double integral, so control stability can be achieved. There are problems such as difficulty.

In view of the foregoing, it is an object of the present invention to eliminate the above-mentioned control instability and to provide a turbine control device which is not affected by play in a mechanical system or transmission delay.

[0020]

SUMMARY OF THE INVENTION The present invention provides a motor-driven synchronous setter for setting a synchronous speed of a turbine, a motor-driven load limiter for setting a load limit value in parallel with an electric power system, An adder that outputs an amount of deviation between the set value of the setter and the detected speed of the turbine; and a second control amount based on the set value of the load limiter and a first control amount based on the amount of deviation from the adder. A mechanical hydraulic control device including a selector for selecting and outputting a low value signal of a control amount, and an electric device for controlling a steam control valve that adjusts a steam flow rate to the turbine based on the control amount from the mechanical hydraulic control device. And a cam control device, wherein the electric cam control device outputs a set value that increases from zero speed to an upper limit speed and an upper limit load when the turbine is started.
A load setter, a second adder for outputting a deviation between a set value of the speed / load setter and a detected speed of the turbine, and a control amount and the second addition from the mechanical hydraulic control device. A controller for controlling the steam control valve based on a control value of any low value of the control amount based on the deviation amount from the device, the synchronous setting device and the load limiter at the stage of turbine startup With the upper limit set, the set value of the speed / load setter of the electric cam control device is increased from zero speed to the upper limit speed, the upper limit load and parallel to the power system. The set values of the setter and the load limiter are narrowed down, and the steam control valve is controlled by a control amount based on the set value from the synchronous setter and the load limiter of the mechanical hydraulic control device. Specially To.

[0021]

When the turbine is started, the steam control valve is controlled by a signal from the turbine speed / load setting device in the electric cam control device. From the start of the turbine, the normal load control is controlled by a signal from the mechanical hydraulic control device. The control is performed, and the stability of the control at the time of starting the turbine is obtained.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the figure, the same parts as those in FIG.

In FIG. 1, reference numeral 30 denotes a speed / load setting device for setting a speed and a load capable of setting a speed from a zero speed to an upper limit speed of the turbine and setting the upper limit load. Signal S set by the device 30
₁ is input to the adder 31. The actual speed signal S ₂ of the turbine from the turbine speed detector 32 is also input to the adder 31. After the difference signal S ₃ between the two is multiplied by a coefficient unit 33, the turbine output command value S ₄
Is input to the low value priority circuit 34.

The above low value preference circuit 34, the speed relay position signal P ₈ of the conventional mechanical hydraulic control device also input, selected lower signal ones of these two signals is turbine flow each steam control valve controller 25a as a command value S _5, are input to 25b, each steam control valve controller 2
The opening of each steam control valve is controlled by the control valve opening command signals v ₁ and v ₂ from 5a and 25b.

When the turbine is started, the main steam stop valve bypass valve 2a and the main steam stop valve 2 are fully opened by the motor 11, and the synchronous setting motor 15 and the load limiting motor 16 (FIG. 4). ) Is set near the upper limit, and the speed relay position signal P ₈ is set near the upper limit.

In this state, as shown in FIG. 2, when the speed / load setting device 30 is operated to increase the speed / load setting signal S ₁ at time t ₁ , the turbine output command inputted to the low value priority circuit 34 is increased. value S ₄ is increased. At this time, the low value priority circuit 34
Is in a relationship of P ₈ > S ₄ , the turbine flow rate command value is S ₅ = S ₄ , and the steam control valve starts to open according to the turbine output command value S ₄ .

In this way, steam flows into the turbine and the turbine starts to rotate, and the amount of turbine rotation is measured by the speed detector 3.
2 and is input to the adder 31 to perform speed closed loop control.

At time t ₂ , when the turbine speed reaches the rated speed, and at time t ₃ , the generator is placed in parallel with the power system and the speed / load setting unit 30 is further increased, the speed / load setting turbine load increases in proportion to the signal S _1.

[0029] Thereafter, to reduce the speed relay position signal P ₈ at time t ₅ to reduced operating the synchronous setting motor and the load limiting electric motor in the machine hydraulic control device, S ₄ = P
_{At 8} (time t ₆ ), the reduction operation of both motors is stopped, and the speed / load setting device 30 is increased to the upper limit.

By such operation, P ₈ <S ₄ , the turbine flow rate command value S ₅ becomes the speed relay position signal P ₈ , and after time t ₆ , the steam control valve is controlled by the control signal from the mechanical hydraulic control device. Is controlled.

In the above embodiment, the setting of the speed / load is performed by one setting device. However, the same applies even if the speed setting device and the load setting device are set separately as shown in FIG. The effect can be obtained.

In FIG. 3, reference numeral 35 denotes a speed setting device which can be set from zero speed to an upper limit speed. The speed setting signal S ₆ of the speed setting device 35 and the actual speed signal S _{2 of the} turbine are set.
There are compared in the adder 36, the deviation signal S ₇ is input to the adder 38 via a coefficient multiplier 37. On the other hand, the load setting signal S ₉ from the load setting unit 39 is also input to the adder 38, and a deviation signal between the two is output as a turbine output command value S ₄ .

[0033] Thus, in the turbine speed increasing control before it parallels the generator and power system, the load setting signal S ₉ was controlled only by the speed setter to zero, after the generator in parallel to the power system The speed setting value is set to a constant rated speed, and load adjustment control is performed by the load setting device. When the control is shifted to the mechanical hydraulic control, the control can be performed by setting the upper limit of the load setting device and / or the speed setting device.

Therefore, in this embodiment, the setting range of the setting device can be limited to the target control only, and the setting accuracy can be improved.

In the above embodiment, the low value priority circuit is provided to select the low value of the two signals. However, switching may be performed by a changeover switch.

[0036]

As described above, according to the present invention, the difference between the actual speed and the speed / load setting signal of the turbine and the low value signal of the position signal from the speed control unit in the mechanical hydraulic control unit are used to control the steam. Since the control valve is controlled, turbine start-up and load control can be performed by a control system that is an electric circuit, and the control of the turbine is stabilized without being affected by backlash unlike control by a mechanical system. Can be changed. In addition, since the turbine is started only by the steam control valve, the control by the main steam stop valve bypass valve becomes unnecessary, and there is an effect that the control device for this is also unnecessary.

[Brief description of the drawings]

FIG. 1 is a system diagram of a main part of a control device of the present invention.

FIG. 2 is an explanatory diagram of an operation of a control signal in the control device of the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a schematic system diagram of a conventional turbine control device.

FIG. 5 is a schematic system diagram of a steam control valve controller of the electric cam control device.

[Explanation of symbols]

 3a Steam control valve 3b Steam control valve 10 Turbine / load control device 15 Synchronous setting motor 16 Load limiting motor 24 Speed relay position detector 25a Steam control valve controller 25b Steam control valve controller 30 Speed / load setting device 32 Turbine Speed detector 34 Low value priority circuit

Claims (1)

(57) [Claims] 1. A motor-driven synchronous setter for setting a synchronous speed of a turbine, a motor-driven load limiter for setting a load limit value in parallel with an electric power system, a set value of the synchronous setter and the turbine An adder for outputting an amount of deviation from the detected speed, and a first based on the amount of deviation from the adder
A mechanical hydraulic control device including a selector for selecting and outputting a low value signal of a second control amount based on the control amount of the load limiter and a second control amount, based on the control amount from the mechanical hydraulic control device. An electric cam control device that controls a steam control valve that adjusts a steam flow rate to the turbine, wherein the electric cam control device increases from zero speed to an upper limit speed and an upper limit load when the turbine is started. A speed / load setter that outputs a set value to be output; a second adder that outputs a deviation amount between a set value of the speed / load setter and a detected speed of the turbine; A controller that controls the steam control valve based on a low control amount of any of a control amount and a control amount based on a deviation amount from the second adder. Synchronous setting With the limiter and the load limiter set to the upper limit, the set value of the speed / load setter of the electric cam control device is increased from zero speed to the upper limit speed, the upper limit load and parallel to the power system, and parallel to the power system. At that stage, the set values of the synchronous setter and the load limiter are narrowed down, and the steam control valve is controlled by a control amount based on the set value from the synchronous setter and the load limiter of the mechanical hydraulic control device. A steam turbine control device, wherein the control is performed.