Method for partial stroke activity test of high-pressure and medium-pressure main throttle valve and control valve of steam turbine

Abstract

The invention discloses a partial stroke activity test method for a steam turbine high and medium pressure main throttle valve and a control valve, and belongs to the technical field of steam turbines, a main throttle valve electromagnetic valve receives an instruction 0 or 1, when the instruction is 0, the electromagnetic valve is powered off, the main throttle valve is fully opened step by step, and when the electromagnetic valve receives the instruction of 1, the electromagnetic valve is powered on, and the main throttle valve is slowly closed; by optimizing the existing steam turbine control system logic and adding partial stroke activity test functions of the high-pressure main throttle valve, the medium-pressure main throttle valve and the medium-pressure control valve of the steam turbine, the valve in a full-open state for a long time can be opened and closed in a small range to prevent the valve from being jammed, meanwhile, the opening change of the valve is small, the steam admission of the steam turbine is hardly throttled, and the service life of the steam turbine is prolonged. And the low side to 8% opening degree of the corresponding side is opened in advance before the medium-pressure control valve moves, and the situation that a medium-pressure main throttle valve is closed to trigger reheater protection is prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbines, and in particular relates to a method for testing the partial stroke activities of a high- and medium-pressure main steam valve and a regulating valve of a steam turbine. Background Art

[0002] A steam turbine, also known as a steam turbine engine, is a rotary steam power device. High-temperature and high-pressure steam passes through a fixed nozzle and becomes an accelerated airflow, which is then sprayed onto the blades, causing the rotor with the blades to rotate and perform work externally. Steam turbines are the main equipment in modern thermal power plants and are also used in the metallurgical industry, chemical industry, and ship power devices.

[0003] The existing ATT valve test function of the steam turbine control system can switch the high and medium pressure main steam valves and medium pressure regulating valve of the steam turbine during the operation of the unit. However, since the current ATT test is a full stroke test of the valve, there are several adverse effects:

[0004] 1. It will cause the turbine cylinder to be in a single-side steam inlet state for a short period of time, which will limit the maximum load of the unit (the unit load during the test is less than 80% of the rated load);

[0005] 2. When the medium-pressure main steam valve is closed, the reheat steam will be blocked, the reheat steam pipe wall temperature will exceed the limit, and when the corresponding side low bypass is closed, the reheater protection will be triggered, causing the unit to trip;

[0006] 3. During the test, the isolation solenoid valve experiences power loss and power-on again. There is a risk that the EH oil pressure may be low due to the solenoid valve plug valve getting stuck during the valve opening process, which may eventually cause the unit to trip. Summary of the invention

[0007] In order to solve the problems raised in the above background technology, the present invention provides a method for testing the partial stroke activities of the high and medium pressure main steam valve and the regulating valve of a steam turbine, which has the characteristics of convenient testing work and accurate results.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for testing the partial stroke activity of a high- and medium-pressure main steam valve and a regulating valve of a steam turbine, comprising the following steps:

[0009] S1. On the original DEH control system screen, new buttons for high-pressure main steam valve activity test, medium-pressure main steam valve activity test, and medium-pressure regulating valve activity test are added;

[0010] The test input instructions of the high-pressure main steam valve activity test button and the medium-pressure main steam valve activity test button are: main steam valve partial stroke activity test input, turbine not tripped, main steam valve position feedback>98%, main steam valve position feedback<90%, pulse signal, AND, RS, OR, TD ON;

[0011] The test input instructions of the medium pressure regulating valve activity test button are: medium regulating valve activity test valve limit target value 90%, medium regulating valve partial stroke activity test input, turbine not tripped, medium regulating valve position feedback>98%, same side low bypass opening ≥8%, medium regulating valve position feedback<90%, pulse signal, AND, RS, OR, TD ON, TD OFF;

[0012] S2. The main steam valve solenoid valve accepts instructions 0 or 1. When the instruction is 0, the solenoid valve loses power and the main steam valve gradually opens. When the solenoid valve receives the instruction 1, the solenoid valve is energized and the main steam valve slowly closes.

[0013] In the present invention, further; in S1, except that the "main steam valve partial stroke activity test is put into operation" sends a 1 signal for 0.5 seconds, the other three conditions such as the turbine not tripping, the main steam valve position feedback > 98% will continue to output a 1 signal once these conditions are met.

[0014] In the present invention, further; in S1, when the "main steam valve partial stroke activity test input" button is not pressed, there is no pulse signal, the 2AND logic block will not output 1, the RS logic block will not output 1, and the 5TD ON will not move, which will not affect the normal operation of the unit.

[0015] In the present invention, further; in S1, when the "main steam valve partial stroke activity test input" button is pressed, a 0.5s pulse is emitted, but when the turbine trips or the main steam valve position feedback > 98% condition is not met, the 2AND block still outputs 0, causing RS to output 0, and 5TD ON will not move, i.e., ensuring that the test cannot be performed when the conditions are not met.

[0016] In the present invention, further; in S1, when the "main steam valve partial stroke activity test is put into operation" button is pressed, a 0.5s pulse is emitted, and when the turbine trips and the main steam valve position feedback is greater than 98% and the conditions are met, AND outputs 0. Since the main steam valve position feedback is less than 90% and is not met, and TD ON is in the disconnected state, the corresponding OR output is 0, the RS logic output is 1, the corresponding OR output is 1, the main steam valve directional solenoid valve is energized, and the main steam valve begins to close slowly; 0.5 seconds later, the pulse signal of "main steam valve partial stroke activity test is put into operation" disappears, output 0, AND output 0, R and S of RS logic are both 0, and the original output 1 remains unchanged; when the main steam valve position feedback is less than 90% and is met, the OR corresponding to RS outputs 1, the RS logic block outputs 0, the directional solenoid valve loses power, the main steam valve slowly opens, and the state before the test is restored, or when the main steam valve position feedback fails, the main steam valve position feedback less than 90% and the condition cannot be met, at this time, the TD receiving the 1 signal ON automatically turns on after a 0.6s delay and outputs 1, making the corresponding OR output 1 and the RS logic block output 0. It can also make the directional solenoid valve lose power, the main steam valve slowly open, and restore to the state before the test.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention optimizes the existing steam turbine control system logic to add steam turbine high-pressure and medium-pressure main steam valves, and a medium-pressure regulating valve partial stroke activity test function, so that the valve that has been in a fully open state for a long time can be opened and closed with a small amplitude to prevent the valve from being stuck. At the same time, the valve opening changes slightly, and almost no throttling is caused to the steam inlet of the steam turbine, and the load output of the steam turbine is not affected. The corresponding side low bypass is opened in advance to 8% opening before the medium-pressure regulating valve is activated to prevent the closure of the medium-pressure main steam valve from triggering the reheater protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a logic block diagram of the partial stroke activity test of the high and medium pressure main steam valve of the present invention;

[0020] Figure 2 It is a logic block diagram of the partial stroke activity test of the middle regulating door of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] See also Figure 1-2 The present invention provides the following technical solution: A method for testing the partial stroke activity of a high- and medium-pressure main steam valve and a regulating valve of a steam turbine, comprising the following steps:

[0024] S1. On the original DEH control system screen, new buttons for high-pressure main steam valve activity test, medium-pressure main steam valve activity test, and medium-pressure regulating valve activity test are added;

[0025] The test input instructions of the high-pressure main steam valve activity test button and the medium-pressure main steam valve activity test button are: main steam valve partial stroke activity test input, turbine not tripped, main steam valve position feedback>98%, main steam valve position feedback<90%, pulse signal, AND, RS, OR, TD ON;

[0026] The test input instructions of the medium pressure regulating valve activity test button are: medium regulating valve activity test valve limit target value 90%, medium regulating valve partial stroke activity test input, turbine not tripped, medium regulating valve position feedback>98%, same side low bypass opening ≥8%, medium regulating valve position feedback<90%, pulse signal, AND, RS, OR, TD ON, TD OFF;

[0027] S2. The main steam valve solenoid valve receives instructions 0 or 1. When the instruction is 0, the solenoid valve loses power and the main steam valve gradually opens. When the solenoid valve receives the instruction 1, the solenoid valve is energized and the main steam valve slowly closes. Explanation of the logic block:

[0028] Pulse signal: When the "Main steam valve partial stroke activity test input" button is manually clicked, a 1 signal is sent for 0.5 seconds, and then it is restored after 0.5 seconds and a 0 signal is sent;

[0029] AND: AND logic block, when the three input quantities in the diagram are all 1, output 1, otherwise output 0;

[0030] RS: RS logic block, R and S are inputs, and Q is output;

[0031]

[0032]

[0033] OR: When any input is 1, the output is 1, and when all inputs are 0, the output is 0;

[0034] TD ON: Indicates that the trigger is normally in the off state. When the input is 0, it does not act. When the input is 1, it delays 0.6 seconds to turn on and outputs 1.

[0035] In addition to the "main steam valve partial stroke activity test input" which sends a 1 signal for 0.5 seconds, the other three conditions, such as the turbine not tripping, the main steam valve position feedback> 98%, etc., will continuously output a 1 signal once these conditions are met;

[0036] S3. When the "Main Steam Valve Partial Stroke Activity Test" button is not pressed, there is no pulse signal, the 2AND logic block will not output 1, the RS logic block will not output 1, and the 5TD ON will not move, which will not affect the normal operation of the unit;

[0037] When the "Main Steam Valve Partial Stroke Activity Test Input" button is pressed, a 0.5s pulse is issued, but if the turbine trips or the main steam valve position feedback is > 98% and the condition is not met, the 2AND block still outputs 0, causing RS to output 0 and 5TD ON will not move, that is, it ensures that the test cannot be carried out when the conditions are not met;

[0038] When the "Main Steam Valve Partial Stroke Activity Test" button is pressed, a 0.5s pulse is emitted, and when the turbine trips and the main steam valve position feedback is greater than 98%, AND outputs 0. Since the main steam valve position feedback is less than 90% and is not satisfied, and TDON is in the disconnected state, the corresponding OR output is 0, the RS logic output is 1, the corresponding OR output is 1, the main steam valve directional solenoid valve is energized, and the main steam valve begins to close slowly; 0.5 seconds later, the pulse signal of "Main Steam Valve Partial Stroke Activity Test" disappears, output 0, AND output 0, R and S of RS logic are both 0, and the original output 1 remains unchanged; when the main steam valve position feedback is less than 90%, the OR corresponding to RS outputs 1, the RS logic block outputs 0, the directional solenoid valve loses power, the main steam valve opens slowly, and the state before the test is restored, or when the main steam valve position feedback fails, the main steam valve position feedback less than 90% condition cannot be met, and the TDON that receives the 1 signal at this time ON automatically turns on after a 0.6s delay and outputs 1, making the corresponding OR output 1 and the RS logic block output 0. It can also make the directional solenoid valve lose power, the main steam valve slowly open, and restore to the state before the test.

[0039] Example 2

[0040] The present embodiment is different from the embodiment 1 in that, specifically, in the partial stroke activity test of the middle regulating valve, the middle pressure regulating valve is precisely positioned and controlled by the electro-hydraulic servo valve, and the valve activity test is carried out by lowering the valve limit of the middle regulating valve. After the activity test is put into operation, the control logic automatically sets the valve limit setting value of the corresponding regulating valve to 90%, and the valve limit change rate is limited to 1.5% opening per second. Under the action of the valve limit, the valve opening is slowly reduced to 90% through the electro-hydraulic servo valve instruction. After maintaining for 5 seconds, the valve limit setting value is automatically restored to 105%, and the valve limit change rate is limited to 1% opening per second. The valve slowly returns to the fully open position under the control of the servo valve.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for partial stroke activity test of high and medium pressure main steam valve and regulating valve of a steam turbine, characterized in that: The steps include: S1. On the original DEH control system screen, new buttons for high-pressure main steam valve activity test, medium-pressure main steam valve activity test, and medium-pressure regulating valve activity test are added; The test input instructions of the high-pressure main steam valve activity test button and the medium-pressure main steam valve activity test button are: main steam valve partial stroke activity test input, turbine not tripped, main steam valve position feedback>98%, main steam valve position feedback<90%, pulse signal, AND, RS, OR, TD ON; The test input instructions of the medium pressure regulating valve activity test button are: medium regulating valve activity test valve limit target value 90%, medium regulating valve partial stroke activity test input, turbine not tripped, medium regulating valve position feedback>98%, same side low bypass opening ≥8%, medium regulating valve position feedback<90%, pulse signal, AND, RS, OR, TD ON, TD OFF; S2. The main steam valve solenoid valve accepts instructions 0 or 1. When the instruction is 0, the solenoid valve loses power and the main steam valve gradually opens. When the solenoid valve receives the instruction 1, the solenoid valve is energized and the main steam valve slowly closes.

2. A method for partial stroke activity test of high and medium pressure main steam valve and regulating valve of a steam turbine according to claim 1, characterized in that: In S1, except for the "main steam valve partial stroke activity test input" which sends a 1 signal for 0.5 seconds, the other three conditions such as turbine not tripping, main steam valve position feedback > 98% will continuously output a 1 signal once these conditions are met.

3. A method for partial stroke activity test of high and medium pressure main steam valve and regulating valve of a steam turbine according to claim 1, characterized in that: In S1, when the "Main Steam Valve Partial Stroke Activity Test" button is not pressed, there is no pulse signal, the 2AND logic block will not output 1, the RS logic block will not output 1, and the 5TD ON will not move, which will not affect the normal operation of the unit.

4. A method for partial stroke activity test of high and medium pressure main steam valve and regulating valve of a steam turbine according to claim 1, characterized in that: In S1, when the "Main Steam Valve Partial Stroke Activity Test" button is pressed, a 0.5s pulse is emitted, but when the turbine trips or the main steam valve position feedback > 98% condition is not met, the 2AND block still outputs 0, causing RS to output 0 and 5TD ON will not move, which ensures that the test cannot be performed when the conditions are not met.

5. The method for partial stroke activity test of high and medium pressure main steam valve and regulating valve of a steam turbine according to claim 1, characterized in that: In S1, when the "Main Steam Valve Partial Stroke Activity Test Input" button is pressed, a 0.5s pulse is issued, and when the turbine trips and the main steam valve position feedback is greater than 98% are met, AND outputs 0. Since the main steam valve position feedback is less than 90% and is not met, and TD ON is in the disconnected state, the corresponding OR output is 0, RS logic output is 1, and the corresponding OR output is 1, the main steam valve direction solenoid valve is energized, and the main steam valve begins to close slowly; After 0.5 seconds, the pulse signal of "main steam valve partial stroke activity test input" disappears, output 0, AND output 0, R and S of RS logic are both 0, and the original output 1 remains unchanged; when the main steam valve position feedback is less than 90%, the OR corresponding to RS outputs 1, the RS logic block outputs 0, the directional solenoid valve loses power, the main steam valve opens slowly, and the state before the test is restored; or when the main steam valve position feedback fails, the main steam valve position feedback less than 90% condition cannot be met. At this time, the TD ON that receives the 1 signal automatically turns on after a 0.6s delay and outputs 1, making the corresponding OR output 1 and the RS logic block output 0, which can also make the directional solenoid valve lose power, the main steam valve open slowly, and the state before the test is restored.

6. A method for partial stroke activity test of high and medium pressure main steam valve and regulating valve of a steam turbine according to claim 1, characterized in that: In S1, in the partial stroke activity test of the middle regulating valve, the middle pressure regulating valve is precisely positioned and controlled by the electro-hydraulic servo valve, and the valve activity test is carried out by lowering the valve limit of the middle regulating valve. After the activity test is put into operation, the control logic automatically sets the valve limit setting value of the corresponding regulating valve to 90%, and the valve limit change rate is limited to 1.5% opening per second. Under the action of the valve limit, the valve opening is slowly reduced to 90% through the electro-hydraulic servo valve instruction. After maintaining for 5 seconds, the valve limit setting value automatically returns to 105%, and the valve limit change rate is limited to 1% opening per second. The valve slowly returns to the fully open position under the control of the servo valve.

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