JPS6371505A - Control process for steam turbine generator - Google Patents

Abstract

PURPOSE:To suppress the pressure fluctuation in both high pressure and low pressure steam lines of a turbine in a short time when the turbine trips, by controlling the steam flow in a bypass line provided between the high pressure and low pressure line according to the previously memorized exhaust steam flow from the turbine. CONSTITUTION:The high pressure steam line 2 of a steam turbine 1 is connected to a low pressure steam line 4 with a bypass line 9, on which a pressure valve 11 and a flow valve 13 are proviced in parallel to each other. A memorized flow controller 12 receives a signal from a flow transmitter 16 which detects the steam flow in an orifice pipe and timingly memorizes the signal so as to give the amount of operation to the flow valve 13 in the case of the trip of the turbine 1 and a generator 7. While the amount of operation corresponds to the control amount which has been memorized just before the trip occurs. Thus, the pressure fluctuation in the high pressure and low pressure steam lines can be suppressed in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a steam turbine power generation device when a trip occurs in a steam turbine and a power generator.

[Prior Art] A steam turbine power generation device supplies high-pressure steam from a high-pressure steam line to a steam turbine, converts the thermal energy of this high-pressure steam into mechanical energy, and uses this mechanical energy to drive a generator to generate electricity. The steam that has been depressurized in the steam turbine is discharged to a low-pressure steam line.

Generally, in this type of steam turbine power generation system, when an abnormality occurs in the steam turbine or generator system, a protection device is activated to cause the steam turbine or generator to take one lip. Fluctuations occur in the steam pressure in the line. Conventionally, pressure fluctuations in the low-pressure steam line were detected, and a pressure controller was used to adjust the valve formed in the bypass line between the two steam lines so that the pressure on the low-pressure side was constant. The steam pressure in both steam lines was controlled by introducing

[Problems to be Solved by the Invention] However, in the conventional control method described above, when the volume on the low-pressure steam line side is small, pressure control follow-up is slow, resulting in large pressure fluctuations. On the other hand, in order to speed up the follow-up of pressure control, the volume can be increased, but in this case, the control during normal operation becomes unstable, so it has been difficult to implement.

Therefore, the present invention provides a control method for a steam turbine power generator that can suppress pressure fluctuations in high-pressure and low-pressure steam lines in a short time even if a trip occurs in a steam turbine and a generator, and can always perform stable control. The purpose is to provide

[Means for solving the problems and their effects] The present invention has the following features:
In order to solve the above problems and achieve the objective, a bypass line is used to connect the high pressure steam line through which high pressure steam is supplied to the steam turbine and the low pressure steam line through which low pressure steam discharged from the steam turbine flows, By storing the steam flow rate discharged from the steam turbine in a timely manner and controlling the steam flow rate to the bypass line according to the stored steam flow rate when the steam turbine and generator trip occurs, the steam flow rate of each high-pressure and low-pressure steam line is controlled. It is designed to adjust the pressure.

[Example] Hereinafter, embodiments of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram showing one embodiment of a control system for a steam turbine power generator constructed based on the method of the present invention.

In the figure, 1 is a steam turbine that takes in high-pressure steam through a high-pressure steam line 2 and converts the thermal energy possessed by this high-pressure steam into mechanical energy. is discharged to a low pressure steam line 4 through an orifice pipe 3. Note that the valve 5 installed in the high pressure steam line 2.
6 is a flow control valve for controlling the flow rate of steam to the turbine, valve 5 is a main blocking valve, and valve 6 is a control valve. Reference numeral 7 denotes a generator that is driven by mechanical energy from the steam turbine 1 and generates electricity, and this generator 7 is equipped with a breaker 8.
A load (not shown) is connected through the

On the other hand, a bypass line 9 is connected between the high pressure steam line 2 and the low pressure steam line 4, and this bypass line 9 has a pressure control valve (hereinafter abbreviated as pressure valve) whose opening degree is adjusted by a pressure controller 10. )
11 and a memorized flow control valve (hereinafter abbreviated as flow valve) 13 whose opening degree is adjusted by a memorized flow controller 12 are interposed in parallel, and a desuperheater 14 is further interposed in series.

The pressure controller 10 inputs a detection signal from a pressure transmitter 15 that detects the steam pressure in the low-pressure steam line 4 as a control 11, and adjusts the operation amount to the pressure valve 11 so that the steam pressure in the low-pressure steam line 4 is constant. It is intended to be given to Further, the memorized flow controller 12 takes in a detection signal from the flow rate transmitter 16 that detects the steam flow rate in the orifice pipe 3 as a control amount and stores it in a timely manner, and when a trip occurs in the steam turbine 1 and the generator 7, The operation amount corresponding to the control amount stored immediately before is given to the flow valve 13.

FIG. 2 is a specific piping diagram for the flow valve 13. The flow valve 13 has a pneumatic operation section, and there are two types of operation systems: one is operated by air supply, and the other is electrically operated using an electric/pneumatic positioner 21 and an air/pneumatic positioner 22. It is configured. In the figure, 23a and 23b indicate air supply sections, and the air from the air supply section 23a is supplied to boosters 24a and 24b and valves 25a and 25b.

It is provided to the flow valve 13 via 26a, 26b, etc., as well as to the air/air positioner 22. Further, air from the air supply section 23b is stored in the volume tank 28 via the check valve 27, and is supplied to the valve 26b at appropriate times. Reference numeral 29 denotes a bypass solenoid valve, and its opening and closing are controlled by a relay circuit (not shown) that operates in response to a solenoid operation signal S from the memorized flow controller 12.

In the control system of this embodiment configured as described above, the operation of the steam turbine 1 is normally controlled by controlling the pressure of low-pressure steam to be constant using the pressure controller 1o. Further, the memorized flow controller 12 rewrites and stores the flow rate signal level given from the flow rate transmitter 16 at appropriate times. In this state, when a trip occurs in the steam turbine 1 and, for example, a trip signal is given to the memorized controller 1-○-ra 12, the controller 12 outputs a steam flow rate corresponding to the signal level immediately before the input of the trip signal. A valve opening command is sent to the flow valve 13 so that it flows through the bypass line 9. Therefore, at the time of turbine trip, the flow valve 13
opens, and steam corresponding to the turbine steam flow rate flows from the high-pressure steam line 2 side through the bypass line 9 to the low-pressure steam line 4.

Here, the relationship between the control layer (turbine steam flow rate) and the manipulated variable (valve opening degree) in the memorized flow controller 12 is set to be the relationship shown in FIG. 3. That is, the operating port is determined by the ratio between the maximum value of the turbine steam flow rate and the maximum flow rate when the flow valve 13 is fully open. For example, if the maximum value of the steam flow port is 150 [T/h] and the maximum flow rate of the flow valve 13 is 130 [T/h], then when the turbine steam flow rate is 100 [T/h],
The operation amount is 86.7 [T/h] flow rate is flow valve 1
The opening command will flow through 3. Note that this setting can be changed freely.

By the way, when the turbine steam flow rate detected by the flow rate transmitter 16 is small, the flow valve 13 reaches a predetermined opening degree in a sufficiently short time using the above-mentioned control method, but when there are many turbine steam flow peaks, There is a delay time for the flow valve 13 to open from a fully open state to an opening corresponding to the flow rate. Therefore, in order to avoid pressure fluctuations due to the flow rate for this delay time, in such a case, -H flow pulp 13
It is controlled so that it is fully open and then closed several seconds later until it reaches an opening corresponding to the turbine steam flow port. Here, the distance from the memorized flow controller 12 is usually 4 to 20 m.
The opening degree of the flow valve 13 is determined by the ADC,
When the flow valve 13 is fully opened, two bypass solenoid valves are used to operate the flow valve 13 directly.

That is, the output circuit for the solenoid operation signal S to the bypass solenoid valve 29 is designed as shown in FIG. In FIG. 4, 40 is a comparison circuit, which compares the turbine steam flow rate PV detected by the flow layer transmitter 16 with the set flow rate X.
When PV≧X, a level signal corresponding to the difference is output to the AND circuit 41. Thus, when the AND is established, that is, the solenoid valve operation signal S is output for a time period of 1 (second) corresponding to the level signal. Note that the relationship between the turbine steam flow rate PV and the time t is set as shown in FIG. Note that this setting can be changed freely.

As is clear from FIG. 5, when the turbine steam flow rate PV is 40% or less of the maximum flow rate, the flow valve 13 is not operated by excitation of the bypass solenoid valve 29, and the electric/pneumatic positioner 21 and the air/air It is operated by a positioner 22.

Therefore, the control operation of the memorized flow controller 12 when a trip occurs in the steam turbine 1 described above is shown in a flowchart as shown in FIG. 6.

That is, when a trip occurs in the steam turbine 1, first, the turbine steam flow rate PV stored immediately before as STI is compared with the set value (40% of the maximum steam flow rate) X, and PV≧X is established. In other words, when the turbine steam flow rate is higher than the set value, the steam valve 29 is energized by outputting the solenoid operation signal S to the bypass solenoid valve 29 in ST2, thereby causing the flow valve 13 to be fully open. shall be. Then, S
At T3, it is determined whether the fully open time of the flow valve 13 has elapsed, which is a time t corresponding to the difference between the turbine steam flow mPV and the set value The bypass solenoid valve 29 is stopped and the bypass solenoid valve 29 is deenergized. Next, the opening mWJ signal of the flow valve 13 is output to the electric/pneumatic positioner 21 so that steam corresponding to the turbine steam flow JiPV stored as ST5 flows through the bypass line 9.

The flow valve 13 is then connected to the electric/pneumatic positioner 21. The air/air positioner 22 operates to close the opening to a predetermined opening degree.

On the other hand, if PV≧X does not hold in ST1, ST5
, and outputs an opening adjustment signal for the flow valve 13 to the electric/pneumatic positioner 21 so that steam corresponding to the turbine steam flow rate PV stored immediately before tripping flows through the bypass line 9. Then, flow valve 1
3 is an electric/pneumatic positioner 21. The opening operation is performed by the action of the air/air type positioner 22 until the opening degree corresponds to the turbine steam flow rate.

Note that the reset operation after a trip occurs is performed according to the procedure shown in FIG. That is, since the memorized door 0-controller 12 switches from automatic mode to manual mode when a trip occurs, the output of the memorized flow controller 12 is manually lowered. Then, the steam flowing through the flow valve 13 gradually increases to the pressure valve 1.
Shift to 1. When it is confirmed that the flow valve 13 is fully open, it is determined whether the generator 7 has been reset, and if it has been reset, the manual mode is switched to the automatic mode. The reset operation is thus completed.

The above is a description of the control method for the occurrence of a trip in the steam turbine 1, and next, a description will be given of a control method for the occurrence of a trip in the generator 7. Since the steam turbine 1 normally does not trip when the generator 7 trips, the flow valve 13 is opened by an opening corresponding to a value obtained by subtracting the no-load operation steam flow rate of the steam turbine 1. That is, if the turbine steam flow rate detected by the flow rate transmitter 16 is PV and the steam flow rate during no-load operation is represented by Q, the opening command output A is A=k (PV-Q) ... (1
). In addition, in the above equation (1), k is a constant (=0
．． 867).

Here, when the turbine steam flow rate is large, the -H flow pulp 13 is fully opened in the same manner as in the case described above,
Flow valve 13 so that the opening command output becomes A after a few seconds.
Close.

Therefore, the control operation of the memorized flow controller 12 at the time of generator trip is performed according to the flowchart shown in FIG.

That is, when a trip occurs in the generator 7, first, the turbine steam flow rate PV stored immediately before as 5T11 is compared with the set value (40% of the maximum steam flow rate) X, and PV≧X is established. If the turbine steam flow rate is higher than the set value, the solenoid operation signal S is sent to the bypass solenoid valve 29 in ST12.
By outputting , the steam valve 29 is excited, and the flow valve 13 is thereby fully opened. Then 5T
At step 13, it is determined whether or not the fully open time of the flow valve 13 has elapsed, which is the time t corresponding to the difference between the turbine steam flow rate PV and the set value The bypass solenoid valve 29 is stopped and the bypass solenoid valve 29 is deenergized. Next, as 5T15, the turbine steam flow rate PV stored at the time of trip occurrence is used to calculate the opening command output A by calculating the equation (1) above, and output this output A to the electric/pneumatic positioner 21. . The flow valve 13 is then connected to the electric/pneumatic positioner 21. The air/air positioner 22 operates to close the opening to a predetermined opening degree.

On the other hand, if PV≧X does not hold in 5T11, ST
15, and after calculating the output A, outputs the opening adjustment signal. The flow valve 13 is then connected to the electric/pneumatic positioner 21. The opening operation is performed by the action of the air/air type positioner 22 in response to the opening degree adjustment signal.

Note that the reset operation after tripping is performed according to the procedure shown in FIG. That is, since the memoized flow controller 12 switches from automatic mode to manual mode when a trip occurs, the output of the memorized door controller 12 is manually lowered. Then, the steam flowing through the flow valve 13 gradually moves toward the pressure valve 11. When it is confirmed that the flow valve 13 is fully opened, it is determined whether the steam turbine 1 has been reset, and if it has been reset, the manual mode is switched to the automatic mode.

The reset operation is thus completed.

As explained above, in this embodiment, the memorized flow controller 12 stores the turbine steam flow rate at appropriate times, and when the steam turbine 1 trips, the steam corresponding to the turbine steam flow rate stored immediately before is bypassed. The operating output is calculated to quickly adjust the opening degree of the flow valve 13 so that the flow flows into the line 9, and when the generator 7 trips, the turbine steam flow rate stored immediately before is adjusted to the steam of the turbine no-load operation. The operating output is calculated according to the value obtained by subtracting the flow rate, and the opening degree of the flow valve 13 is promptly adjusted. Therefore, according to the present embodiment, it is possible to sufficiently suppress pressure fluctuations occurring in the high-pressure steam line 2 and the low-pressure steam line 4 in a short time when the steam turbine 1 and the generator 7 trip. can. Also, under normal conditions, constant pressure control in the low-pressure steam line is performed as in the past. Therefore, stable control is always performed, and it is expected that the efficiency of the turbine generator will be improved.

[Effects of the Invention] As detailed above, according to the present invention, a bypass is created between the high-pressure steam line through which high-pressure steam supplied to the steam turbine flows and the low-pressure steam line through which low-pressure steam discharged from the steam turbine flows. By connecting the steam turbine to the bypass line, storing the steam flow rate discharged from the steam turbine in a timely manner, and controlling the steam flow rate to the bypass line according to the steam flow rate stored when the steam turbine and generator generate 1-rip, high pressure and Since the steam pressure in each low-pressure steam line is adjusted, even if a trip occurs in the steam turbine or generator, pressure fluctuations in the high-pressure and low-pressure steam lines can be suppressed in a short time, ensuring stable control at all times. It is possible to provide a method for controlling a steam turbine power generation device that can perform the following steps.

[Brief explanation of the drawing]

Figures 1 to 9 are diagrams showing one embodiment of the present invention, in which Figure 1 is a system diagram of a control system, Figure 2 is a piping diagram of a flow valve, and Figure 3 is a diagram of a memorized flow controller. The characteristic diagram, FIGS. 4 and 5 are diagrams for explaining the operation of the bypass solenoid valve, and FIGS. 6 to 9 are flowcharts for explaining the operation of the steam turbine and the generator when a trip occurs, and a flowchart for explaining the reset operation. 1...Steam turbine, 2...High pressure steam line, 4...
...Low pressure steam line, 7... Generator, 9... Bypass line, 10... Pressure controller, 11... Pressure valve, 12... Memorized flow controller, 13... Flow valve, 21... Electric/pneumatic positioner, 22... Air/pneumatic positioner, 29.
...Bypass solenoid valve. Applicant's agent Patent attorney Takehiko Suzue Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] In a steam turbine power generation device in which thermal energy possessed by steam is converted into mechanical energy by a steam turbine, and this mechanical energy is used to generate electricity in a generator, high-pressure steam flows through which high-pressure steam is supplied to the steam turbine. A bypass line connects the line and a low-pressure steam line through which low-pressure steam discharged from the steam turbine flows, and the flow rate of the low-pressure steam discharged from the steam turbine is memorized in a timely manner. 1. A method of controlling a steam turbine power generator, comprising controlling a steam flow rate of the bypass line according to a stored steam flow rate during a trip.