JPH01277608A - Load control for power generation plant - Google Patents

Abstract

PURPOSE:To absorb the imbalance between a boiler and a turbine by reducing a power generation quantity instruction to an actual load when a partial load cut-off state is detected and by reducing the load of a steam turbine to an actual power generation quantity load by adjusting a turbine bypass valve. CONSTITUTION:If a partial load cut-off setting signal is over an actual load in the state where the connection point (a) of a load signal selecting relay 33 is in the partial load cut-off mode, a run-back signal or FCB instruction (opening of a power generator main relay) is outputted into a combustion control system 7 through a load signal selecting relay 34. When a signal is inputted into a connection point (b), and the partial load cut-off operation is generated, a load setting analogue memory 13 follows to the actual load value for a prescribed time after the load is cut off, and also a load variation rate limiter 17 performs following for a prescribed time, and a governor valve 23 and an intercept valve 22 are controlled, having the actual load after the cut-off of the load as new set load. Thus, the imbalance of the load between a boiler and a turbine can be absorbed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a load control method for a power plant equipped with a turbine bypass device.

[Prior Art] Conventionally, in a power generation plant equipped with a turbine bypass device, when a generator switch is opened, PCB control is used to reduce the load to a predetermined load by controlling the so-called generator main relay to an open state. It was being done.

However, no equivalent consideration was given to control when the generator switch does not function as an oven and the load suddenly decreases, that is, when a partial load is cut off.

[Problem to be solved by the invention] For this reason, especially in cases where the grid power is weak (for example, in developing countries), when the load suddenly changes, it is not only the case between the generator main relay (PCB), but also the conventional The control method alone cannot deal with this problem, and it is not possible to supply power in a stable state, resulting in poor reliability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a load control method for a power plant that can suppress an increase in main steam pressure due to a sudden load reduction in a power plant, and can absorb load imbalance between boiler turbines.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a power generation plant equipped with a turbine/bypass device including a turbine bypass valve for adjusting the amount of steam supplied to the steam bin. When a partial load cut-off state is detected, the power generation command is tracked to the actual load value, and the amount of steam supplied to the steam turbine is adjusted by the turbine bypass valve, so that the steam turbine is controlled to match the actual power generation amount. This is a load control method for a power generation plant, characterized in that the power generation amount is controlled by reducing the load to .

[Operation] The present invention minimizes the imbalance between the load command and the actual load that occurs during load shedding by reducing the power generation command to the actual load and having the steam turbine control control the power generation amount. I can do it.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing one embodiment, and FIG. 2 is a diagram showing the control logic of FIG. 1. Boiler 1 is
It is equipped with heaters SH and RH, which convert water supplied from the water supply system and the low-temperature reheat steam system into steam, respectively, and this steam is passed through the main steam system to a high-pressure steam turbine (hereinafter referred to as high-pressure turbine). ) 2, which rotationally drives the high-pressure turbine 2, and the steam is also supplied to a medium-low pressure steam turbine (hereinafter referred to as medium-low pressure turbine) 3 via a high-temperature reheat steam system, whereby the medium-low pressure turbine 3 is driven to rotate.

The generator 4 includes a high pressure turbine 2 and a medium/low pressure turbine 3.
rotational driving force is transmitted. The steam after doing work in the medium and low pressure turbine 3 is converted into condensate by a condenser 5, and this water is supplied via a condensate system and a pump 6 to a water supply system that supplies the heater SH.

The boiler 1 is supplied with air from an air supply source (not shown) and fuel from a fuel supply source (not shown), and the amounts of these are determined by the opening degrees of the damper 8 for controlling the air flow rate and the fuel control valve 9. The opening degrees of the damper 8 and the fuel control valve 9 are controlled by control signals from the combustion control system 7. The output signal of the generator 4 is detected by the transducer 10, and the detected actual load signal (megawatt (Mw) signal) is input to one input terminal of the deviation signal monitor 11, and the other input terminal is input to the deviation signal monitor 11. Load setting device 12
The setting value set by is stored in analog memory 1 for load setting.
3, this stored value is input, and the deviation monitor 11
The deviation between the two is determined, and the energizing paths of load signal selection relays 33 and 34, which will be described later, are controlled based on this deviation.

The subtracter 14 stores the actual load signal from the transducer 10 and the load setting analog memory 13; the set value is input, and the subtracted output of both is set to the maximum value set by the load limit setting device 18. /Minimum value limiter 19, and the output limited here is input to the cooperative control system 20. In this cooperative control system 20, a turbine demand and a boiler demand are obtained, and this turbine demand is given to a turbine control system 21, where the intercept valve 2 inserted in the high temperature reheat steam system
2, a control signal for the governor valve 23 inserted in the main steam system is generated and output. The boiler demand output from the cooperative control system 20 is input to the first input terminal of the main steam pressure control system 35. The set value set by the main steam pressure setting device 24 is stored in the main steam pressure setting analog memory 25, and this stored value is input to the second input terminal of the main steam pressure control system 35. The amount of steam flowing into the main steam system is detected by the transducer 26 and converted into a main steam pressure signal, and this converted main steam pressure signal is input to the third input terminal of the main steam pressure control system 35. A control signal obtained by the main steam pressure control system 35 is given to the load signal selection relay 34.

A pressure bias signal and a 0 bias signal are input to the pressure bias selection relay 27, and the signal obtained here and the memory value stored in the main steam pressure setting memory 25 are added by an adder 28, The added value is input to the subtracter 29, where the main steam pressure signal modified by the transducer 26 is subtracted, and the result of this subtraction is manually input to the turbine bypass control system 30, where the high pressure turbine Bypass valve 31 and medium and low pressure turbine
An opening control signal is given to the bypass valve 32.

In addition to the control signal from the main steam pressure control system 35, a control signal from the load signal selection relay 33 is input to the load signal selection relay 34. Load signal selection relay 34
A boiler mask signal obtained from the combustion control system 7 is input to the combustion control system 7.

Here, the features of the present invention will be explained with reference to FIG. 2(a) and 2(b) respectively show the relationship between the deviation monitor 11 and the load signal selection relays 33 and 34 in FIG. 1. In the deviation monitor 11, the actual load signal from the transducer 10 Monitor the deviation from the load setting signal stored in the load setting analog memory 13,
As shown in Fig. 2 (a), when the deviation exceeds a predetermined value (when load setting>actual load + α) and it is between the main relays of the electrical equipment, the on-delay timer 41
, are input to the AND circuit 43 via the inverting circuit 42, and when the AND condition is satisfied here, the AND circuit 43
Partial load shedding mode is activated by the signal output from
The signal is output to the connection point a, and the signal output when the AND condition is satisfied in the AND circuit 43 is the off-day 1
/ It is output to the connection point via the timer 44.

Then, when the connection point a is in the partial load shedding mode as shown in FIG. Setting> Actual load + β (where β is the load corresponding to the turbine bypass valve capacity), the AND circuit 45
When the AND condition is satisfied and any one of the logic signal, runback command, or PCB command (between generator main relays) is input to the OR circuit 46, the load signal selection relay 34 is activated. The signal path is changed to 84C, the signal path of the load signal selection relay 33 becomes a-d, and when the runback command is input to the load signal selection relay 33, the signal path becomes b-d. , and when a PCB command is input to the load signal selection relay 33, the signal path becomes b-d.

In addition, in Fig. 2 (b), when the boiler does not need to reduce its load, that is, before partial load shedding occurs, the load setting value is equal to the load β for the turbine valve and Ibus valve capacity and the actual load. (After occurrence) If it is not larger than the value of the load added, the AND condition of the AND circuit 45 does not hold, so
Control to reduce the boiler load is not performed.

Furthermore, as shown in Fig. 2(c), when a signal is input to the connection point and a partial load shedding operation occurs [7], the load setting analog memory 13 stores the actual load value after the load shedding for a specified period of time. (the set time of the off-delay timer), and the load change rate limiter 17 tracks the actual load value after load shedding for the specified time. Therefore, the actual load of the governor valve 23 and the intercept valve 22 is controlled by using the actual load value after the load cutoff as a new load setting.

Further, when it is necessary to reduce the boiler load, the boiler control system does not control the main steam pressure, so the main steam pressure can be controlled by turbine bypass control instead. In this case, the value stored in the main steam pressure setting analog memory 25 (output signal) is added to the adder 2 during normal operation.
By cutting the pressure bias signal added through 8, the signal path of the pressure bias selection relay 27 is changed to a -
By controlling the main steam pressure, it is possible to suppress an increase in main steam pressure due to a sudden load reduction in the power plant, and to absorb the imbalance in the load between the boss and f-seater turbines.

According to the embodiment of the present invention described above, the control logic shown in FIG. 2 is added to the conventional load control device of a power generation plant, the power generation amount command is reduced to the actual load, and the power generation amount is controlled to control the steam turbine. By controlling the amount, it is possible to minimize the imbalance between the load command and the actual load that occurs during load shedding.

[Effects of the Invention] According to the present invention, it is possible to provide a load control method for a power generation plant that can suppress an increase in main steam pressure due to a sudden load reduction in a power generation plant and can absorb load imbalance between boiler turbines.

[Brief explanation of the drawing]

FIG. 1 is a system diagram for explaining an embodiment of the load control method for a power generation plant according to the present invention, and FIG. 2 is a diagram for explaining the control logic of FIG. 1. 1... Turbine, 2... High pressure turbine, 3... Medium and low pressure turbine, 4... Generator, 5... Capacitor,
6... Pump, 7... Combustion control system, 8... Damper for air flow rate control, 9... Fuel control valve, 10-day load signal transducer, 11... Deviation signal monitor, 13.
... Analog memory for load setting, 16... Analog memory for load change rate setting, 17... Load change rate limiter,
33.34... Relay for selecting music or signal. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In a power generation plant equipped with a turbine bypass device including a turbine bypass valve for adjusting the amount of steam supplied to a steam turbine, when a partial load cutoff state is detected,
The power generation amount is controlled by tracking the power generation amount command to the actual load value and reducing the amount of steam supplied to the steam turbine to a load equivalent to the actual power generation amount by adjusting the turbine bypass valve. A load control method for a power generation plant characterized by the following.