Manual setting method for the electrical neutral position of the pilot valve in the hydraulic servo system of the speed governor.

Abstract

The manual setting method for the electrical neutral position of the pilot valve in the hydraulic servo system of the speed controller includes the following steps: Step 1: After the stepper motor is re-centered, the valve core position of the pilot valve is set to the electrical neutral position when the control system returns to the balanced state, and the electrical neutral position value Y of the pilot valve is recorded. 中 Proceed to step 2; Step 2: Set the electrical neutral position of the main pressure regulating valve and record the electrical neutral position value Z of the main pressure regulating valve. 中 Proceed to step 3; Step 3: In the electric / manual mode of the speed governor, perform a step test on the directional guide vanes. After the system stabilizes following the test, record the Z value of the main pressure valve position feedback channel at this time. 开 Step 4: Perform a step test on the closing guide vane opening. The conditions can be the same as those for the step test on the opening guide vane opening. After the system stabilizes following the test, record the Z value of the main pressure regulating valve position feedback channel at this time. 关 Step 5: Perform electrical neutral position setting of the speed controller pilot valve. The pilot valve electrical neutral position setting method of the present invention is simple and efficient, and the setting results are accurate and reliable.

Description

Technical Field

[0001] This invention relates to the field of hydraulic servo systems for speed governors, and specifically to a method for manually adjusting the electrical neutral position of the pilot valve in a hydraulic servo system for speed governors. Background Technology

[0002] The Chinese patents “A self-diagnostic, self-positioning, and adaptive method for mid-position in a governor hydraulic servo system” (ZL: 201810113905.8); “A method for automatic intelligent mid-position positioning of the main distribution electrical system of a governor” (ZL: 202010489958.7); and “A system and method for automatic intelligent mid-position setting of the governor hydraulic servo system” (ZL: 201910024102.X) series of technical solutions can realize the mid-position setting function of the proportional valve and the main distribution electrical system of the governor hydraulic servo system. This function is suitable for hydropower units that use proportional valves (or proportional valves + stepper motors and other redundant configurations) and main distribution and relay devices as the actuation structure. Hydropower units that use a stepper motor + pilot valve and main distribution / relay unit as the actuation structure have a different control structure than those that use a proportional valve (or a proportional valve + stepper motor, etc., with redundant configuration) and main distribution / relay unit as the actuation mechanism. The electrical neutral position setting of the pilot valve is usually based on the valve core position of the pilot valve in the manual state after the stepper motor is reset and the control system returns to balance. This setting is usually not very accurate.

[0003] Currently, there is no mature and accurate method for manually setting the electrical neutral position of the governor's pilot valve. Inaccurate setting of the electrical neutral position of the governor's pilot valve often leads to frequent adjustments of the governor's hydraulic servo system and problems such as the inability to adjust the guide vane opening to the correct position, resulting in adjustment quality issues. Summary of the Invention

[0004] This invention provides a method for manually setting the electrical neutral position of the pilot valve in a governor's hydraulic servo system. It is applicable to hydropower units using a stepper motor + pilot valve and main / relay actuators as the actuators. During unit maintenance, this method is used to manually set the electrical neutral position of the pilot valve in the governor's hydraulic servo system, aiming to solve adjustment quality problems such as frequent adjustments and inability to adjust the guide vane opening to the correct position caused by inaccurate electrical neutral position setting of the governor's pilot valve.

[0005] The technical solution adopted in this invention is as follows:

[0006] The manual setting method for the electrical neutral position of the pilot valve in the hydraulic servo system of the speed governor includes the following steps:

[0007] Step 1: After stepper motor 3 is re-centered, the control system restores the valve core position of pilot valve 2 to the balanced state, sets it to the electrical neutral position, and records the pilot valve electrical neutral position value Y. 中 Proceed to step 2;

[0008] Step 2: Set the main pressure regulating valve 1 to its electrical neutral position and record the electrical neutral position value Z of the main pressure regulating valve. 中 Proceed to step 3;

[0009] Step 3: In the electric / manual mode of the speed governor, perform a step test on the directional guide vanes. After the system stabilizes following the test, record the Z value of the main pressure distribution valve position feedback channel at this time. 开 ;

[0010] Speed ​​governor controllers typically have three control modes: automatic, electric manual (EMT), and mechanical manual (MA). In automatic control mode, the speed governor controller uses PID closed-loop control to control the turbine guide vane opening. In EMT control mode, the speed governor controller uses EMT open-loop control to control the turbine guide vane opening. In MAMA control mode, the speed governor controller uses MAMT open-loop control to control the turbine guide vane opening.

[0011] Step 4: Perform a step test on the closing guide vane opening. The conditions can be the same as those for the step test on the opening guide vane opening. After the system stabilizes following the test, record the Z value of the main pressure regulating valve position feedback channel at this time. 关 ;

[0012] Step 5: Perform electrical neutral position setting for the governor pilot valve:

[0013] If (Z) 开 +Z 关 ) / 2-Z 中 <-ε, gradually increase the pilot valve electrical neutral setting value Y in steps of positive integer i. 中 Return to step 3;

[0014] If (Z) 开 +Z 关 ) / 2-Z 中 When ε > ε, the pilot valve electrical neutral setting value Y is gradually decreased with a step size of i. 中 Return to step 3;

[0015] If |(Z) 开 +Z 关 ) / 2-Z 中 If ||ε, then the pilot valve electrical neutral position setpoint Y at this time 中 With proper settings, the electrical neutral position diagnostics and setting of the pilot valve are complete.

[0016] The step size *i* is a positive integer, determined comprehensively based on the measurement accuracy of the main and auxiliary position sensors, the required speed and accuracy of the pilot valve's electrical neutral position setting, and the magnitude of the pilot valve's electrical neutral position setting accuracy. 1 represents the highest unit accuracy for the pilot valve's electrical neutral position setting value. A larger step size *i* results in a faster setting speed but a decrease in setting accuracy; a smaller step size *i* results in a slower setting speed but an increase in setting accuracy. ε > 0, and ε is typically determined comprehensively based on the measurement accuracy of the main and auxiliary position sensors and the magnitude of the pilot valve's electrical neutral position setting accuracy. To improve the accuracy of the pilot valve's electrical neutral position setting, multiple tests can be conducted under different or identical opening conditions for repeated verification.

[0017] The present invention provides a method for manually setting the electrical neutral position of the pilot valve in a hydraulic servo system of a speed governor. The technical advantages are as follows:

[0018] 1) This invention is used for manual setting of the electrical neutral position of the guide valve during the maintenance of hydro-generator units. It can solve the problem of frequent adjustment of the hydraulic follow-up system of the governor caused by inaccurate setting of the electrical neutral position of the guide valve of the governor.

[0019] 2) The pilot valve electrical neutral setting method of the present invention is simple and efficient, and the setting result is accurate and reliable. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0021] Figure 1 This is a schematic diagram of the hydraulic servo system of the speed controller in this invention.

[0022] Figure 2 This is a schematic diagram of the closed-loop control structure of the electronic control system of the present invention.

[0023] Figure 3 It is a mechanical structure diagram of the controlled object;

[0024] Figure 3 In the diagram, the various line types representing pipelines are as follows:

[0025] Pressure oil supply pipeline

[0026] Control piping

[0027] oil return line

[0028] Figure 4 This is a flowchart of a manual setting method for the electrical neutral position of a speed controller pilot valve according to the present invention. Detailed Implementation

[0029] The speed controller hydraulic follow-up system includes: human-machine interface device 11, controller 12, controlled object, sensor, and communication medium.

[0030] The controlled objects include stepper motor 3, pilot valve 2, main pressure regulating valve 1, and hydro-generator set 13, which are directly or indirectly controlled objects. The mechanical structure diagram of the controlled objects is shown below. Figure 3 As shown.

[0031] The sensor is an electronic component or a collection thereof that measures the state information parameters of various controlled objects, such as displacement sensors, speed measuring devices, and power transmitters. Figure 1 and Figure 4 As shown:

[0032] Pilot valve displacement (position) sensor 5 measures the position of the pilot valve spool;

[0033] The main pressure regulating valve displacement (position) sensor 4 measures the position of the main pressure regulating valve core.

[0034] The relay displacement sensor 15 is used to measure the guide vane position Y;

[0035] The communication medium includes hardwired cables, network cables, and other communication cables, and its function is to transmit information flow between the human-computer interaction device 11, the controller 12, the controlled object, and the sensor.

[0036] The hydro-generator unit 13 is connected to the power grid 14, the power grid 14 is connected to the PT residual voltage frequency measuring device 17, and the PT residual voltage frequency measuring device 17 is connected to the controller 12.

[0037] The speed measuring device and power transmitter 16 includes a power transmitter module and a speed signal device. The power transmitter module NSD-PTM-V1.2 measures the power signal of single-phase or three-phase AC voltage and current signals. Through a host computer interface, the measured power signal can be converted into standard RS232, RS485, and Ethernet TCP / IP / IP / IP communication protocols; or output as a 4-20mA and 0-10V analog signal. The speed signal device RES3000 uses a high-performance industrial-grade CPU as the core control unit to achieve intelligent control of the turbine unit's speed and frequency.

[0038] The human-machine interaction device 11 is generally a touch screen, which realizes the human-machine interaction function. Users can input parameters such as the preliminary electrical neutral setting value of the guide valve of the speed controller hydraulic follow-up system and control commands into the controller 12 through the human-machine interaction device 11. The controller 12 can display the position, frequency and other status information of the controlled object in real time and inform the user through the human-machine interaction device 11.

[0039] The human-machine interface device 11 collects the status signals of the controlled object through sensors, and processes various input signals in real time according to the control parameters and commands issued by the user through the human-machine interface device 11, and outputs control signals to the controlled object. The controller 12 can be a PLC, PCC, ARM, etc., of various brands. The control method adopts the classic closed-loop control theory. A schematic diagram of the closed-loop control structure of the electrical control system is shown below. Figure 2 As shown.

[0040] like Figure 2 As shown, the guide vane opening control loop aims to ensure that the guide vane opening feedback follows the given guide vane opening, which is achieved through an electrical negative feedback closed loop. The main control loop aims to ensure that the main control position follows the main control setpoint, which is achieved through a mechanical negative feedback closed loop where the main control position follows the pilot valve position, and an electrical negative feedback closed loop where the pilot valve position follows the main control setpoint. In other words, the stepper motor 3 is displaced based on the difference between the main control position setpoint and the pilot valve position feedback, thereby controlling the pilot valve position. This is achieved through a mechanical negative feedback closed loop where the main control position follows the pilot valve position. The mechanical negative feedback closed loop structure diagram of the main control position following the pilot valve position is shown below. Figure 3 As shown. Figure 3 The serial number, name, code, and quantity of each component are shown in Table 1:

[0041] Table 1. Component serial number, name, code, and quantity

[0042] Serial Number name code name quantity Remark 1 Main pressure regulating valve 200DR 1 DN250 2 pilot valve 201DR 1 DN250 3 Stepper motor 102EB 1 4 Main pressure valve position sensor 111MN 1 5 pilot valve position sensor 112MM 1 6 Guide vane position sensor 101MM 1 7 relay JLQ 2 8 Relay ring JLH 1 9 Pressure oil tank YYG 1 10 Return to fuel tank HYX 1

[0043] Depend on Figure 3 It can be seen that the valve sleeve of the pilot valve and the valve core of the main pressure regulating valve are mechanically rigidly connected. When the valve core of the pilot valve moves downward, the P port and A port of the pilot valve 201DR are connected, and the Y end of the main pressure regulating valve 1 is supplied with pressure oil. The valve core of the main pressure regulating valve moves downward, causing the valve sleeve of the pilot valve to move downward. When the valve core and the valve sleeve of the pilot valve move to the same displacement, the P port and A port of the pilot valve 201DR are no longer connected. At this time, the mechanical following system enters a steady state.

[0044] When the valve core of the pilot valve moves upward, the T port and A port of the pilot valve 201DR are connected, and the Y end of the main pressure regulating valve is connected to pressureless return oil. The valve core of the main pressure regulating valve moves upward, causing the valve sleeve of the pilot valve to move upward. When the valve core and valve sleeve of the pilot valve move to the same displacement, the T and A ports of the pilot valve 201DR are no longer connected. At this time, the mechanical following system enters a steady state.

[0045] As can be seen from the above process, this mechanical structure realizes a mechanical negative feedback closed-loop structure in which the position of the main valve (valve core) follows the position of the pilot valve (valve core).

[0046] The manual setting method for the electrical neutral position of the pilot valve in the hydraulic servo system of the speed governor includes the following steps:

[0047] Step 1: Initial electrical neutral position setting of the speed controller pilot valve:

[0048] In manual mode, after stepper motor 3 is reset, the control system restores the valve core position of pilot valve 2 to the balanced state, sets it to the electrical neutral position, and records the pilot valve electrical neutral value Y. 中 Proceed to step 2;

[0049] Speed ​​governor controllers typically have three control modes: automatic, electric manual (EMT), and mechanical manual (MAM). In automatic control mode, the speed governor controller uses a PID closed-loop control method to control the guide vane opening. In EMT mode, the speed governor controller uses an EMT open-loop control method to control the guide vane opening. In MAM mode, the speed governor controller uses a mechanical open-loop control method to control the guide vane opening. Specifically, in MAM mode, the stepper motor automatically returns to its intermediate balance position, and the pilot valve spool and main distribution valve spool follow suit.

[0050] Step 2: Set the electrical neutral position of the main pressure regulating valve 1 using existing technology, and record the electrical neutral position value Z of the main pressure regulating valve. 中 Proceed to step 3;

[0051] The existing technology for setting the electrical neutral position of the main pressure distribution valve 1 specifically refers to a series of automatic electrical neutral position setting technologies for the main pressure distribution valve disclosed in the existing technologies "A method for self-diagnosis, self-positioning, and adaptive adjustment of the neutral position in a hydraulic servo system for a speed governor" (Authorization Announcement No.: CN108468615B); "An automatic intelligent setting method for the neutral position in a hydraulic servo system for a speed governor" (Authorization Announcement No.: CN109695533B); and "An automatic intelligent positioning method for the electrical neutral position of the main pressure distribution valve for a speed governor" (Authorization Announcement No.: CN111749840B). Step 3: In the electric manual state of the speed governor, perform a step test on the opening direction guide vane. After the test, once the system is balanced and stable, record the Z value of the main pressure distribution valve position feedback channel at this time. 开 ;

[0052] The step test of the guide vane in the opening direction refers to the step test of the guide vane opening in the direction of increasing guide vane opening. The test is conducted by changing the electric manual guide vane opening setting value to change the guide vane opening from the initial value to the electric manual guide vane opening setting value.

[0053] Step 4: Perform a step test on the closing guide vane opening. The conditions can be the same as those for the step test on the opening guide vane opening. After the system stabilizes following the test, record the Z value of the main pressure regulating valve position feedback channel at this time. 关 ;

[0054] The guide vane opening step test in the direction of decrease refers to the test of the guide vane opening step in the direction of decrease. The test is conducted by changing the electric manual guide vane opening setting value to change the guide vane opening from the initial value to the electric manual guide vane opening setting value.

[0055] Step 5: Perform electrical neutral position setting for the governor pilot valve:

[0056] If (Z) 开 +Z 关 ) / 2-Z 中 <-ε, gradually increase the pilot valve electrical neutral setting value Y in steps of positive integer i. 中 Return to step 3;

[0057] If (Z) 开 +Z 关 ) / 2-Z 中 When ε > ε, the pilot valve electrical neutral setting value Y is gradually decreased with a step size of i. 中 Return to step 3;

[0058] If |(Z) 开 +Z 关 ) / 2-Z 中 If ||ε, then the pilot valve electrical neutral position setpoint Y at this time 中 With proper settings, the electrical neutral position diagnostics and setting of the pilot valve are complete.

[0059] The step size i is a positive integer, which is determined comprehensively based on the measurement accuracy of the main and auxiliary position sensors, the speed requirement of the pilot valve's electrical neutral position setting, and the accuracy requirement of the pilot valve's electrical neutral position setting.

[0060] If the main position sensor has a higher measurement accuracy requirement, the pilot valve's electrical neutral setting speed requirement is not high, and the pilot valve's electrical neutral setting accuracy requirement is higher, then the step size i can be set smaller; conversely, if the main position sensor has a lower measurement accuracy requirement, the pilot valve's electrical neutral setting speed requirement is higher, and the pilot valve's electrical neutral setting accuracy requirement is lower, then the step size i can be set larger.

[0061] 1 represents the highest unit precision of the pilot valve's electrical neutral setting value; since step size i is a positive integer and 1 is the smallest positive integer step size, 1 represents the highest unit precision of the pilot valve's electrical neutral setting value.

[0062] A larger step size i results in a faster tuning speed but a decrease in tuning accuracy; a smaller step size i results in a slower tuning speed but a higher tuning accuracy.

[0063] ε>0, and ε is usually determined by a combination of the measurement accuracy of the main position sensor and the electrical neutral setting accuracy of the pilot valve.

[0064] If the main position sensor has higher measurement accuracy requirements and the pilot valve has higher electrical neutral setting accuracy requirements, then ε can be set smaller; conversely, if the main position sensor has lower measurement accuracy requirements and the pilot valve has lower electrical neutral setting accuracy requirements, then ε can be set larger.

[0065] To improve the accuracy of the pilot valve's electrical neutral setting, multiple tests can be conducted under different or the same opening conditions for repeated verification.

[0066] Example:

[0067] The speed governor control mode of a certain unit at Xiangjiaba Hydropower Station was switched to online B-set controller, electric manual operation mode, with stepper motor + pilot valve and main distribution and relay as the actuator, guide vane opening to 70%, fast door closed to keep the unit casing dry, speed governor in no-load state, forced input of unit speed 50HZ signal, and manual setting test of the electric neutral position of the speed governor pilot valve.

[0068] The steps for manually setting the electrical neutral position of the governor pilot valve are as follows:

[0069] (1): Initial setting of the electrical neutral position of the speed controller pilot valve: In the manual state of the reference machine, after the stepper motor is reset to neutral, the valve core position of the pilot valve is set to the electrical neutral position when the control system returns to the balanced state. The electrical neutral position value Y of the pilot valve is recorded. 中 Proceed to step (2);

[0070] (2): Use existing technology to set the neutral position of the main distribution equipment and record the neutral position value Z of the main distribution equipment. 中 Proceed to step (3);

[0071] (3): In the electric manual mode of the speed governor, perform a step test on the guide vane opening. Select the 70% opening condition and perform an electric manual step test on the guide vane opening from 70% to 75%. After the test, wait for the system to stabilize and record the main and auxiliary position feedback channel value Z at this time. 开 Proceed to step (4);

[0072] (4): Conduct a step test on the closing guide vane opening. Select the 70% opening condition and conduct an electric and manual step test on the guide vane opening from 70% to 65%. The starting point of the closing guide vane opening step test should be consistent with that of the opening guide vane step test, and the step amplitude should be consistent. After the system is balanced and stable after the test, record the Z value of the main and auxiliary position feedback channel at this time. 关 ;

[0073] (5): Perform electrical neutral setting of the speed controller pilot valve. If (Z 开 +Z 关 ) / 2-Z 中<-ε, with a step size of positive integer i = 1 (1 being the highest unit precision of the pilot valve's electrical neutral setting value), gradually increase the pilot valve's electrical neutral setting value Y. 中 Return to step (3); if (Z 开 +Z 关 ) / 2-Z 中 When the value is greater than ε, the electrical neutral setting value Y of the pilot valve is gradually decreased in steps of i=1. 中 Return to step (3); if |(Z 开 +Z 关 ) / 2-Z 中 If ||ε, then the pilot valve electrical neutral position setpoint Y at this time 中 With proper settings, the electrical neutral position diagnostics and setting of the pilot valve are complete.

Claims

1. A method for manually setting the electrical neutral position of the pilot valve in a speed governor hydraulic follow-up system, characterized in that, Includes the following steps: Step 1: After the stepper motor (3) is re-neutralized, the control system restores the valve core position of the pilot valve (2) to the balanced state, sets it to the electrical neutral position, and records the electrical neutral position value Y of the pilot valve. 中 Proceed to step 2; Step 2: Set the electrical neutral position of the main pressure regulating valve (1) and record the electrical neutral position value Z of the main pressure regulating valve. 中 Proceed to step 3; Step 3: In the electric / manual mode of the speed governor, perform a step test on the directional guide vanes. After the system stabilizes following the test, record the Z value of the main pressure distribution valve position feedback channel at this time. 开 ; Step 4: Perform a step test on the closing guide vane opening. The conditions can be the same as those for the step test on the opening guide vane opening. After the system stabilizes following the test, record the Z value of the main pressure regulating valve position feedback channel at this time. 关 ; Step 5: Perform electrical neutral position setting for the governor pilot valve: If (Z) 开 +Z 关 ) / 2-Z 中 <-ε, gradually increase the pilot valve electrical neutral setting value Y in steps of positive integer i. 中 Return to step 3; If (Z) 开 +Z 关 ) / 2-Z 中 When ε > ε, the pilot valve electrical neutral setting value Y is gradually decreased with a step size of i. 中 Go back to step 3; If | (Z) 开 +Z 关 ) / 2-Z 中 If ||ε, then the pilot valve electrical neutral position setpoint Y at this time 中 With proper settings, the electrical neutral position diagnostic and setting of the pilot valve is complete. Where: ε>0, and ε is determined by combining the measurement accuracy of the main position sensor and the electrical neutral setting accuracy of the pilot valve; If the main position sensor has higher measurement accuracy requirements and the pilot valve has higher electrical neutral setting accuracy requirements, then ε should be set smaller; conversely, if the main position sensor has lower measurement accuracy requirements and the pilot valve has lower electrical neutral setting accuracy requirements, then ε should be set larger.

2. The method for manually setting the electrical neutral position of the pilot valve in the hydraulic servo system of the speed controller according to claim 1, characterized in that: The step size i is a positive integer, which is determined comprehensively based on the measurement accuracy of the main and auxiliary position sensors, the speed accuracy requirements of the pilot valve's electrical neutral position setting, and the magnitude of the pilot valve's electrical neutral position setting accuracy.

3. The method for manually setting the electrical neutral position of the pilot valve in the hydraulic servo system of the speed controller according to claim 2, characterized in that: 1 represents the highest unit accuracy of the pilot valve's electrical neutral setting value; the larger the step size i, the faster the setting speed but the lower the setting accuracy; the smaller the step size i, the slower the setting speed but the higher the setting accuracy.

Images