JPH08151902A - Load controller for steam turbine - Google Patents

Abstract

PURPOSE: To realize a device which can control load fluctuation during a valve testing period, and can reduce a burden to an operator. CONSTITUTION: A load controller for a steam turbine is equipped with a controller 5 for controlling a load during a valve testing period, which is arranged in parallel to a controller 4 for controlling a load during a normal operating period, and switching relay 6 which changes from the controller 4 to the controller 5 when valves are tested. When the valves are tested, the controller 5, is used, which can appropriately control the loads in relation to steam regulating valves 17 who are not tested. Hereby, load fluctuation during the valve testing period can be minimized, and the steam turbine can be stably operated, and a burden to an operator during a testing period can be reduced as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device for a steam turbine, which is applied to a steam turbine of a thermal power plant and can easily perform a turbine valve test.

[0002]

2. Description of the Related Art In a thermal power plant, generally,
As shown in FIG. 2, a steam turbine is formed by a high-pressure turbine 12, an intermediate-pressure turbine 13, and a low-pressure turbine 14 and coupled to a generator 11. The high-pressure turbine 14 has two main left and right main trains that form a main steam system. The steam pipe 15 is connected, and two high temperature reheat steam pipes 18 of left and right forming a reheat steam system are connected to the intermediate pressure turbine.

Regarding each of the above steam systems, two valves are provided in each of the left and right systems. In the main steam system, the main steam stop valve 16 and the steam control valve 17 form left and right tandem couples, and reheat is performed. Similarly, in the steam system, the reheat steam stop valve 19 and the intercept valve 20 form left and right tandem couples.

The steam control valve 17 is used in the load control device 2
The load control device 21 controls the steam control valve 17 in the following manner.

The load request signal 1 is transmitted to the comparator 3 via the rate-of-change setting device 7, and the output signal of the turbine first stage rear pressure transmitter 2 (this signal is the load) is also supplied to the comparator 3. (Used as a feedback signal of) and a control signal is generated by the load control controller 4 so as to make the deviation (output of the comparator 3) zero, and then to the steam control valve 17 via the E / H converter 8. Is transmitted. The steam control valve 17 to which this control signal is input controls the load by opening and closing.

In the steam turbine of the thermal power plant, the steam valves thereof, that is, the main steam stop valve 16 and the steam control valve 1
7. In order to prevent sticking of the reheat steam stop valve 19 and intercept valve 20, etc., and to confirm that the above valves operate without abnormality, during load operation, alternate once a week for each of the left and right 2 series. It is necessary to open and close the valve. This open / close confirmation work is called a turbine valve test or a stem-free test.

In the conventional turbine valve test for the steam control valve 17 and the main steam stop valve 16 relating to load control, the following procedure is generally performed. That is, first, after the turbine load is reduced to 75% or less, the test switch on one side (for example, the right side) is operated to first fully close the right steam control valve 17, and then to the right main steam stop valve 1 as well.
Confirm that 6 is fully closed.

Next, the test switch is released, first it is confirmed that the main steam stop valve 16 is fully opened, and then the test switch is operated to fully open the steam control valve 17. Repeat the same test on the left side and restore the load after the test.

The main steam stop valve 16 basically controls the rotation speed when the steam turbine is started.

[0010]

In the conventional turbine valve test, the load is set to 75% or less as described above, and the right and left two steam control valves and the main steam stop valve are connected to the right steam control valve and the right main steam stop valve. Separate the valve set, the steam control valve on the left side, and the main steam stop valve on the left side, and perform a valve test for each set.The steam flowing through the left and right valves before the test is temporarily tested during the valve test. It was supposed to flow to only one set of valves on one side.

In this case, since the valve test is carried out by reducing the load to 75% or less, the steam flow rate is a flow rate which can be sufficiently processed by only one of the pair of valves which is not under test, and there is no static problem.

However, the valve test is carried out during load operation, and of course, load fluctuation may occur. However, the load control controller for controlling the steam control valve has two sets of load fluctuations. Since the valve was adjusted to correspond to it, the response delay often caused disturbance in load control.

In this case, since the operator has to manually perform the unstalling adjustment, a great burden is imposed on the operator. The present invention is intended to solve the above problems.

[0014]

A load control device for a steam turbine according to the present invention comprises a comparator which inputs a load request signal and a turbine first stage rear pressure signal and outputs a deviation signal, and a deviation signal from the comparator. For a steam turbine equipped with a controller for load control during normal operation that controls the steam control valves provided in each of the multiple series of the main steam system connected to the steam turbine by inputting In the load control device, the valve test load control controller connected to the comparator, and the control signals output from the controller connected to the valve test load control controller and the normal operation load control controller, respectively. It features a switching relay that switches and inputs to the steam control valve.

[0015]

In the above, during normal operation of the steam turbine, the controller for load control during normal operation outputs and controls a control signal for each steam control valve.

On the other hand, during the valve test, the turbine load is kept below a certain value, and the switching relay is used to switch from the load control controller during normal operation to the load control controller during valve test. It is controlled by the load operation controller.

The above-described valve test load control controller is a controller having a high response speed so that the load can be properly controlled by the steam control valve excluding the valve test. The steam control valve is controlled at a faster response speed than the load control controller.

Therefore, when there is a load change during the valve test, the steam control valve is controlled more quickly than when using the load control controller during normal operation, so that the load change is suppressed and the load during the valve test is reduced. Can be stabilized.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steam turbine load control system according to an embodiment of the present invention will be described with reference to FIG. The steam system of the thermal power plant to which the present embodiment is applied is the same as that of the conventional device, and therefore its description is omitted.

The apparatus of the present embodiment shown in FIG. 1 has a change rate setting device 7 for inputting a load request signal 1 and a turbine first stage installed in a high pressure turbine 14 for inputting the load request signal 1 from the setting device 7. A comparator 3 which inputs an output signal of the rear pressure transmitter 2 and outputs a deviation signal thereof, a load control controller 4 which inputs a deviation signal from the comparator 3 and outputs a control signal such that the deviation signal becomes zero, and In the load control device including an electric / hydraulic (hereinafter, referred to as E / H) converter 8 that inputs a control signal from the controller 4 to control the right and left steam control valves 17, the load control controller 4
A switching relay 6 connected between the switching relay 6 and the E / H converter 8, and a valve test load control controller 5 connected between the switching relay 6 and the comparator 3.

In the above, during the normal operation of the steam turbine, the deviation signal output from the comparator 3 is input to the load control controller 4 as in the case of the conventional apparatus, and the controller 4 inputs the deviation signal. The right and left steam control valves 17 are controlled via the to control the load.

On the other hand, during the valve test, the turbine load is set to 7
When the load control controller 4 is set to 5% or less and the load control controller 4 connected between the comparator 3 and the E / H converter 8 is switched to the valve test load control controller 5 by the switching relay 6, the valve is operated similarly to the conventional device. A test is performed, and after the valve test is completed, the switching relay 6 switches from the valve control load control controller 5 to the load control controller 4, and then the load is returned to the original state.

Controller 5 for load control during valve test
Is a controller having a characteristic suitable for controlling the load in one line and having a faster response speed than the load control controller 4. Since the steam control valve 17 is controlled in a quicker response than the control controller 4, the load can be kept constant and the load can be stabilized during the valve test.

[0024]

The load control device for a steam turbine of the present invention includes a controller for load control during valve test, which is arranged in parallel with a controller for load control during normal operation, and a controller for load control during normal operation during valve test. The load control controller for valve test shall be equipped with a switching relay for switching from the load control controller to the valve test load control, and capable of performing appropriate load control for the steam control valve that is not in the valve test during the valve test. By
It is possible to minimize load fluctuations during valve testing, which not only enables stable operation of the steam turbine but also reduces the burden on operators during testing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a steam turbine load control device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional device.

[Explanation of symbols]

 1 load request signal 2 turbine first stage rear pressure signal transmitter 3 comparator 4 controller for load control 5 controller for load control during valve test 6 switching relay 7 load change rate setter 8 load control E / H converter 9 frequency ( Rotation speed) Transmitter 10 Rotation speed control controller 11 Rotation speed control E / H converter 12 Low pressure turbine 13 Medium pressure turbine 14 High pressure turbine 15 Main steam pipe 16 Main steam stop valve 17 Steam control valve 21 Load control device

Claims (1)

[Claims] 1. A steam turbine which outputs a deviation signal by inputting a load request signal and a turbine first stage rear pressure signal, and a control signal which inputs the deviation signal from the comparator and makes it zero At the time of normal operation that controls the steam control valves provided in each of the main steam systems connected to the steam turbine load control device equipped with a load control controller, during the valve test connected to the above comparator A load control controller, and a switching relay that is connected to the load control controller during the valve test and the load control controller during normal operation and that switches the control signals output from the controller to the steam control valve. Load control device for steam turbine.