JPS6032905A - Turbine controller - Google Patents

Abstract

PURPOSE:To automatically and effectively perform both load control and bleed pressure control without interfering each other by incorporating both a bleed pressure controller and a load controller in a bleeder turbine controller and placing both the controllers under cooperative control. CONSTITUTION:A speed control circuit 17, a load limiter 19, a bleed pressure control circuit 30, a valve opening detector 41 and so on are incorporated in the controller of a bleeder turbine 9. When a bleed regulation valve 8 is not opened fully yet, the output of an analog memory 43 is cut off by a contact point 44 and a high-value priority circuit 33 gives priority to the bleed air pressure control signal of the circuit 30. When the bleed regulation valve 8 is opened fully and the contact point 44 is closed, the high-value priority circuit 33 gives priority to the output of the memory 43. After the bleed regulation valve is opened fully, when the pressure of bleed air is reduced inspite of increased demand for it, the output of the bleed pressure control circuit 30 is increased. Once the output thereof exceeds the output of the memory 43, bleed pressure control is performed in response to the output signal of the circuit 30.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a turbine control device, and particularly to a turbine control device that effectively controls the extraction pressure in an extraction condensation turbine to smoothly cope with the turbine load. The present invention relates to a turbine control device suitable for carrying out such operations.

[Technical background of the invention]

In general, extracted condensing turbines are often used as industrial steam turbines that effectively utilize extracted steam from the turbine. On the other hand, recently, the construction of power plants whose main purpose is to generate electricity, but also to supply steam to water plants that desalinate seawater, which require a large capacity of steam, has been increasing internationally. In this case, the extraction condensate turbine constructed in conjunction with the water production plant is required to stably supply both electric power and steam. Furthermore, in extraction condensation turbines whose main purpose is to generate electric power, there is a strong demand for higher performance steam turbines.

As shown in the operating characteristics diagram in Figure 1, a general extraction condensation turbine is designed so that the extraction pressure ExtP is constant and the maximum efficiency is obtained at the maximum extraction rated output Lmax, and the efficiency at partial load is has been ignored to some extent. Incidentally, in FIG. 11, the vertical axis is the extraction pressure, and the horizontal axis is the turbine load. However, in extraction condensation turbines whose main purpose is to generate electric power, they are often operated to match electric power demand gK, and performance at partial loads cannot be ignored. Therefore, in the extraction condensation turbines and power generation solenoid constructed for this purpose, the extraction pressure is controlled by the extraction adjustment valve built into the extraction turbine only at intermediate loads, and the extraction adjustment valve is fully opened at intermediate loads and above. The current practice is to increase the bleed pressure.

As with conventional bleed condensing turbines, if the bleed regulator valve and the low-pressure turbine after the bleed stage are made large to obtain the maximum rated bleed output, the bleed regulator will always throttle the bleed air except when operating at the maximum rated rated output. The steam turbine is under control, and the loss of pressure due to the bleed control valve reduces the performance of the steam turbine. In addition, the steam pressure required for a fresh water production brand is about 2 to 3 Kp/cdtt, and if a low-pressure turbine is designed with this steam condition,
Not only does the low-pressure turbine become larger, but high performance cannot be expected. On the other hand, as shown in the operating characteristics diagram in Figure 2, if the low-pressure turbine is designed so that the bleed air control valve is fully opened at intermediate loads or higher and the bleed air pressure is raised above the rated bleed pressure, then the bleed air control valve can be Valve squeeze! l
1 loss can be eliminated, and at the same time, it is possible to improve the performance of the low-pressure turbine. In addition, the extracted air at an intermediate load or higher may be used by reducing the pressure to the pressure of 2 to 3 Kp/crlt required for the water production plant using a pressure reducing valve provided on the water production plant side.

[Problems with background technology]

As mentioned above, in the extraction condensing turbine where the extraction pressure is controlled only at intermediate loads by the extraction control valve installed before the low-pressure turbine inlet and the steam control valve installed at the high-pressure turbine inlet, the extraction pressure control method is As long as there is no change from the conventional method, problems such as those listed below will occur.

(11) When the load on the steam turbine is increased from a state where the bleed air control valve is fully open, the amount of steam inflow from the steam control valve on the high pressure turbine inlet side increases, causing a pressure rise in the bleed stage. When the bleed pressure control device detects this, it closes the steam control valve and opens the bleed control valve to prevent the rise in bleed pressure.However, the bleed control valve is fully open before the load increases and cannot be opened. This is not possible.In order to prevent the bleed air pressure from increasing, the opening of the steam control valve must be reduced to its original opening.As described above, - the pressure setting value of the bleed air pressure controller If an attempt is made to increase the load after the bleed air adjustment valve is fully opened, the bleed air pressure control device will suppress the load increase, making it impossible to increase the load.

(2) On the other hand, there is a method of increasing the bleed pressure setting on the condition that the bleed air adjustment valve is fully open, but if you increase the bleed pressure setting in steps, the throttling control will be performed due to the bleed air adjustment valve being busy. However, the objective of improving performance mentioned above cannot be delayed. Further, changing the pressure set value in a stepwise manner is not preferable because it causes a large disturbance to the bleed pressure control.

(3) It is also possible to change the bleed pressure set value according to the operating status of the steam turbine, but in this case the set value is a link between the steam turbine output and the bleed air flow rate, which is extremely complicated and undesirable in practice. .

[Purpose of the invention]

Therefore, the object of the present invention is to overcome the drawbacks of the above-mentioned prior art,
Before the bleed control valve is fully opened, the bleed condensate turbine is controlled so that the bleed pressure and turbine load do not interfere with each other, and after the bleed control valve is fully opened, the bleed pressure control is automatically stopped.
To provide a turbine control device that enables efficient control of an extraction condensation turbine by controlling the extraction condensation turbine so that an increase in extraction pressure does not affect an increase in turbine load. It is something.

[Summary of the invention]

In order to achieve the above object, the present invention includes a bleed air control valve that adjusts bleed air pressure to a steam turbine connected to an bleed air system;
A bleed pressure control means for adjusting the opening of the bleed air regulator, an opening detection means for detecting the opening of the bleed air regulator, and a pressure control means for controlling the opening of the bleed air regulator; a signal generating means for generating a bleed pressure control signal, a memory means for receiving and following or holding the bleed pressure control signal, an opening/closing means for turning on and off an output signal of the memory means, and a signal generating means. Selection means for selecting the signal from the and the signal from the opening/closing means based on their respective levels, and sending the selected signal to the bleed pressure control means as a control signal;
Based on the output of the opening detection means, the storage means is controlled to the holding side on the condition that the steam turbine load is intermediate or above and the extraction control valve is fully opened, and otherwise the storage means is controlled to the follow-up side. and an opening/closing means that holds the opening/closing means in an on state when the steam regulating valve is fully open, and when the steam regulating valve becomes less than fully open, the output of the storage means becomes equal to the bleed pressure control signal. and second control means for canceling the on state of the turbine and turning it off.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a block diagram of a turbine control device according to an embodiment of the present invention.

In the configuration shown in the figure, steam generated in the boiler 1 enters the high-pressure turbine 4 through the main steam stop valve 2 and the steam control valve 3. A part of the steam worked in the high-pressure turbine 4 is extracted from the high-pressure turbine exhaust through a check valve 5 and a gate valve 6 to a water production plant (not shown).

The remaining exhaust gas from the high-pressure turbine 4 flows into the low-pressure turbine 9 via a bleed control valve 8 provided in the crossover pipe 7. The steam that has done work in the low-pressure turbine 9 is led to a water doubler 10 and condensed. A steam turbine consisting of a high pressure turbine 4 and a low pressure turbine 9 drives a generator 1 to generate electricity.

The actual rotation speed of the steam turbine is detected as a frequency signal proportional to the rotation speed of the turbine by a speed detection gear 12 directly connected to the rotor of the steam turbine and an electromagnetic pickup 13 installed opposite to the speed detection gear 12. be done. This frequency signal is converted by a frequency/voltage converter 14 into an analog signal proportional to the frequency. The actual rotational speed of the turbine is calculated by comparing it with the setting signal from the speed setting device 16 by the adder 15. The speed error signal that is the output of the adder 15 is converted by the speed control circuit 17 into a speed control signal that matches the speed regulation rate. This speed control signal is compared with the limit signal from the load limiter 19 by a low value priority circuit 18, and the lower signal is given priority and output as an opening request signal for the steam control valve and the bleed air control valve. One of the outputs of the low value priority circuit 18 is added to an adder to convert the output signal of the bleed air pressure control circuit 30 into the low value priority circuit 31. High value priority circuit 33, coefficient unit 47
is added to the steam control valve opening request signal obtained in response to the
The steam control valve opening degree is set to 13. This steam control valve opening signal is compared with the actual steam control valve opening signal by an adder 21, and the error signal is current amplified by an A-power amplifier Masuda.

- The output of the blower amplifier n is converted from a blood signal to a mechanical stroke signal by an electro-oil converter Masuda. This stroke signal is given to the steam regulating valve oil cylinder train, where the steam regulating valve 3
is amplified to the operating force that can drive the steam regulator, and adjusts the steam regulator valve 3 to an opening equal to the steam regulator opening request No. 45. The mechanical stroke signal of the electro-hydraulic converter is detected by the differential transformer 5, demodulated by the demodulator 26, and then negatively fed back to the adder 21 as the steam control valve opening number 1.

On the other hand, the extracted air pressure, which is the exhaust gas of the high-pressure turbine 4, is detected by the pressure detector 27 as an analog signal proportional to the extracted air pressure. The actual bleed pressure signal, which is the output of the bleed pressure detector M, is compared with the set signal from the bleed pressure set signal by an adder path.

The error signal between the bleed pressure setting signal and the actual bleed pressure signal is converted into a bleed pressure control signal that matches the bleed pressure adjustment rate by the bleed pressure control circuit. Incidentally, in the case of bleed pressure control, a configuration may be adopted in which a compensating function for phase lead/lag etc. is added to stabilize the bleed pressure control.

Now, one of the bleed pressure control signals which is the output of the bleed pressure control circuit 30 is sent to the bleed limiter 32 by the low value priority circuit 31.
The lower value is selected and outputted.Furthermore, one of the outputs of the low value priority circuit 31 is inputted to the high value priority circuit 33, which outputs the bleed air adjustment valve opening signal from the storage circuit. They are compared and the higher value is selected and output. One of the outputs of the high value priority circuit 33 is input to the adder block via the coefficient multiplier 47, and is added to the steam control valve opening signal from the load control system. The other output of the high value priority circuit 33 is added to the bleed air adjustment valve opening signal from the load control system by an adder via a coefficient unit 48, and is converted into an bleed air adjustment valve opening signal.

Incidentally, the constant set in the coefficient unit 47 is set in such a way that the bleed pressure control does not interfere with the load control. It is set so that the absolute value of the amount of change in load with respect to the change in the control valve is equal.

On the other hand, the constant set in the coefficient unit 48 is negative
In order to prevent the II control from interfering with the bleed pressure control, the change in the flow rate of the moderation control valve due to a change in the load control sign is set to be equal to the change in the flow rate of the bleed air control valve.

One of the outputs of the adder is compared with the actual opening degree signal of the bleed control valve in the adder 35. The bleed air control valve opening error signal, which is the output of the adder 35, is power amplified by a power amplifier 36 and input to an electro-hydraulic converter 37.

The electro-hydraulic converter 37 converts the bleed air adjustment valve opening request No. 48 into a mechanical stroke signal proportional to this, and sends it between the bleed air adjustment valve oil cylinders. The stroke signal is from the bleed air control valve oil cylinder 38
The operating force is amplified and the bleed air control valve 8 is controlled to the opening degree equal to the bleed air control valve opening request signal. The mechanical stroke signal that is the output of the electro-hydraulic converter 37 is detected by the differential transformer 39, converted to an analog signal by the demodulator 40, and sent to the adder 35 as the actual opening signal of the bleed control valve. The other output of the 0 extraction pressure control circuit (equipment) that is negatively fed back is connected to contact 42.
The signal is input to the analog memory 43 via. In other words, while the contact 42 is closed, the analog memory 43 follows and stores the output between the bleed air pressure control circuits.The output of the analog memory 43 is given to the high value priority circuit 33 via the contact 44, giving priority to the low value. It is compared with the bleed pressure control signal obtained as the output of the circuit 31, and the higher control signal is sent out as the bleed pressure control signal. The contact 42 is controlled to open and close by an opening detector 41 provided on the output side of the adder 34, which detects that the bleed air adjustment valve opening error signal is fully open. That is, when the bleed air control valve 8 is not fully opened, the contact 42 closes, and the analog memory 43 stores and outputs the same value as the output between the bleed air pressure control circuits.

On the other hand, when the opening degree of the bleed air control valve 8 reaches full open, the opening degree detector 4 operates to open the contact 42, and the analog memory 43
stores the value immediately before the contact 42 opens and holds it as it is.

The contact 44 also receives a contact signal from a detector 46 which compares the output signal of the low value priority circuit 31 and the output signal of the analog memory 43 with an adder 45 and detects that the error is zero, and a contact signal from the bleed air control valve. 0 switch operated by a relay circuit 49 having a self-hold function f operated by a contact signal of an opening detector 41 that detects that 8 is fully open;
The contact 44 closes when the bleed air control valve 8 is fully opened, and the output of the low value priority circuit 3J is equal to the output of the analog memory 43, so that the bleed air control valve 8 opens at an opening less than full open.

FIG. 4 is a circuit configuration diagram showing the basic configuration of the relay circuit 49 shown in FIG. 3. In the figure, contact 41
a is operated by the opening degree detector 41 of the bleed air control valve 8. In other words, when the opening degree of the bleed air adjustment valve 8 becomes fully open, the contact point 41
a closes. When contact 41a closes, relays A and B are excited, and contact 42 and contact I close.

As a result, relay C and relay D are energized. Relay C
When energized, contact 51 closes. The contact 46b is an output contact of the detector 46 that detects that the output of the low value priority circuit 31 and the output of the analog memory 43 are equal. When the two river forces are equal, the contact 46b is open, and otherwise it is closed.

The relay D is energized by the closing of the contact or by the closing of both the contact 46b and the contact 5, and the relay D is energized by the contact 44 being closed.
Close.

The above operation can be summarized as follows.

While the bleed air control valve 8 is fully open, the analog memory 43 always automatically follows the bleed pressure control signal and continues to store its value. When the bleed air control valve 8 is fully opened, automatic tracking in the analog memory 43 is stopped and the value immediately before tracking is stored. When the bleed air control valve 8 is not fully opened, the output of the analog memory 43 is disconnected from the high value priority circuit at the contact 44.
During this time, the high value priority circuit or the bleed pressure control signal from the bleed pressure control circuit I is prioritized. When the bleed air control valve 8 is fully opened and the contact 44 is closed, the analog memory 43 and the output of the bleed air pressure control circuit I are compared by the high value priority circuit 33. When the bleed air control valve 8 is fully opened, if the turbine load is increased any further, the actual bleed air pressure will increase, so the output of the bleed air pressure control circuit will decrease.

However, the analog memory 43 stores the value immediately before the bleed air control valve 8 is fully opened, and the high value priority circuit 33 prioritizes the output of the analog memory 43. In other words, the request signal once sent from the bleed pressure control circuit blade to the steam control valve 3 and the bleed control valve 8 is held at the value immediately before the bleed control valve 8 is fully opened. The claw 9 makes it possible to increase the turbine load after fully opening the bleed air control valve 8, which was not possible with the prior art, by operating the bleed air pressure control circuit blade. That is, when the demand for bleed air increases and the bleed pressure falls below the set value while the bleed air control valve 8 is fully open, the output of the bleed air pressure control circuit J increases. When this output becomes larger than the output of the analog memory 43, the high value priority circuit 33 sends out the output of the bleed pressure control circuit (9) with priority, and the bleed pressure is controlled based on this signal. Therefore, the bleed pressure does not fall below the set value. Further, in this state, when the bleed air control valve 8 is throttled to less than full open, the output of the analog memory 43 starts to follow the output of the bleed air pressure control circuit (9).

In this case, since the output side contact 44 of the analog memory 43 opens when the output of the analog memory 43 and the output of the bleed air pressure control circuit are equal, no impact occurs at all due to the switching.

By performing the control operations as described above, control characteristics as shown in the bleed pressure control characteristic diagram in FIG. 2 can basically be obtained. In FIG. 2, the bleed pressure shown by the two-dot chain line indicates the rising state of the bleed pressure in the non-bleed air amount after the bleed control valve 8 is fully opened, and the bleed pressure shown by the one-dot chain line indicates the state of increase in the bleed pressure after the bleed control valve 8 is fully opened. This shows the increase in bleed pressure at the maximum bleed amount after

〔Effect of the invention〕

As described above, in the turbine control device of the present invention, when the steam turbine is at an intermediate load or below and the load state is up to the point where the bleed air control valve is fully opened, the bleed pressure is controlled to be constant, and moreover, the bleed pressure is controlled at a constant level and This allows for control to prevent interference. On the other hand, when the turbine load is above intermediate load, i.e. when the bleed air control valve is fully open, the control signal for the bleed air pressure control is held at the value just before the bleed air control valve was fully opened, so that it does not interfere with the turbine load control. This makes it possible to control the In addition, even if the actual bleed pressure falls below the bleed pressure set value due to bleed demand when the turbine load is above the intermediate load and the bleed bleed control valve is fully open, the bleed air will be given priority over turbine load control. By controlling the pressure, it is possible to satisfy the bleed air demand. Thus, according to the present invention, hj1
It is possible to realize a turbine control device that can perform turbine load control and extraction pressure control effectively and automatically without interfering with each other.

[Brief explanation of the drawing]

Fig. 1 is a control characteristic diagram of extraction pressure in a general extraction condensation turbine; Fig. 2 is a control characteristic diagram of extraction pressure suitable for improving the performance of a low-pressure turbine. Block Diagram of Turbine Control Device FIG. 4 is a circuit configuration diagram of the relay circuit shown in FIG. 3. DESCRIPTION OF SYMBOLS 1... Boiler, 3... Steam control valve, 4... High pressure turbine, 8... Bleed air control valve, 9... Low pressure turbine, 17... Speed control circuit, 18... Low value priority circuit,
Addition: extraction pressure control circuit, 31: low value priority circuit,
33... High value priority circuit, 41... Opening degree detector, 43
...Analog memory, 49...Relay circuit. Applicant's agent Kiyoshi Inomata 1711 (]" Figure 3 Figure 4 Figure 3

Claims (1)

[Scope of Claims] 1. A bleed air control valve for adjusting the bleed air pressure to a steam turbine connected to the bleed air system; bleed air pressure control means for adjusting the opening of the bleed air control valve; an opening detecting means for detecting the opening of the valve; a signal generating means for generating a bleed pressure control signal that is constant below an intermediate load of the steam turbine and responsive to the load above the intermediate load; and a signal generating means that receives the bleed pressure control signal. , storage means for following or holding this,
opening/closing means for turning on and off the output signal of the storage means;
a selection means for selecting a signal from the signal generation means and a signal from the opening/closing means based on their respective levels, and sending the selected signal to the bleed pressure control means as a control signal; and based on the output of the opening degree detection means; a first control means that controls the storage means to the holding side on the condition that the steam turbine load is intermediate or above and the extraction control valve is fully opened, and to the follow-up side otherwise; When the valve is fully open, the opening/closing means is maintained in an on state, and when the steam control valve is less than fully open, the opening/closing means is maintained on the condition that the output of the storage means becomes equal to the bleed pressure control signal. and second control means for canceling the on state and turning on the turbine control device. 2. The turbine control according to claim 1, wherein the selection means includes a high value priority circuit that outputs a higher level signal with priority among two input signals. Device.