阅读说明：本技术 一种液压变桨故障快速定位和安全停机方法 (Hydraulic variable propeller fault rapid positioning and safe shutdown method ) 是由 王志奎 崔逸南 陈明明 陈亚芬 于 2019-12-13 设计创作，主要内容包括：本发明公开了一种液压变桨故障快速定位和安全停机方法,包括以下步骤：变量数据采集、故障阀块快速判定和定位以及选择停机方式,变量数据采集为主控PLC通过CANopen通讯连接变桨PLC,变桨PLC连接连接带有反馈信号的电磁换向阀、比例换向阀、压力传感器以及位移传感器,两个带有反馈信号的电磁换向阀和一个三位四通比例换向阀信号通过变桨PLC传输到指控PLC作为控制逻辑判定,位移传感器监测缸体位移值获得实际桨距角；本发明采用带有反馈信号的电磁换向阀,准确的判定变桨故障阀块；通过对故障阀块的判定,执行不同方式下的停机,提高了机组的安全性；通过快速定位故障,降低现场运维人员的工作难度,提高工作效率。(The invention discloses a method for quickly positioning faults and safely stopping a hydraulic variable propeller, which comprises the following steps: the control method comprises the steps of variable data acquisition, quick judgment and positioning of a fault valve block and selection of a shutdown mode, wherein the variable data acquisition is that a master control PLC is connected with a variable pitch PLC through CANopen communication, the variable pitch PLC is connected with an electromagnetic directional valve with feedback signals, a proportional directional valve, a pressure sensor and a displacement sensor, the two electromagnetic directional valves with the feedback signals and a three-position four-way proportional directional valve signal are transmitted to a finger control PLC through the variable pitch PLC to be used as control logic judgment, and the displacement sensor monitors a displacement value of a cylinder body to obtain an actual pitch angle; the invention adopts the electromagnetic directional valve with the feedback signal to accurately judge the pitch fault valve block; shutdown in different modes is executed through judgment of the fault valve block, so that the safety of the unit is improved; through the quick location trouble, reduce on-spot fortune dimension personnel's the work degree of difficulty, improve work efficiency.)

1. A hydraulic variable propeller fault rapid positioning and safe shutdown method is characterized by comprising the following steps: variable data acquisition, rapid judgment and positioning of a fault valve block and selection of a shutdown mode,

the variable data acquisition is that a master control PLC is connected with a variable pitch PLC through CANopen communication to realize communication control and variable data transmission, fault early warning and shutdown judgment, the variable pitch PLC is connected with an electromagnetic directional valve with feedback signals, a proportional directional valve, a pressure sensor and a displacement sensor, the signals of the two electromagnetic directional valves with the feedback signals and the three-position four-way proportional directional valve are transmitted to a finger control PLC through the variable pitch PLC to be used as control logic judgment, the pressure sensor is provided with two sensors for respectively monitoring the pressure of an energy accumulator of a hydraulic station and the pressure of an energy accumulator of an actuator, and the displacement sensor monitors a displacement value of a cylinder body to obtain an actual pitch angle;

the fault valve block is quickly judged and positioned to be the actual pitch angle of the unit, the pressure of the hydraulic station energy accumulator and the pressure of the actuator energy accumulator as the judgment conditions of the fault valve block, the on-off of the electromagnetic reversing valve with signal feedback can be fed back to the on-off signal feedback of the master control PLC, the running working state of the electromagnetic reversing valve is monitored, the control logic of the unit is to carry out program monitoring through the feedback DI of the electromagnetic reversing valve with the feedback signal and the DO output instruction of the electromagnetic reversing valve, and the corresponding fault judgment is executed by combining the required pitch angle and the actual pitch angle of the unit, so that the fault valve block is judged, and the fault point is accurately positioned;

after the shutdown mode is selected to locate the fault, the shutdown mode is switched by judging the size of the pitch angle, so that the safety and reliability of the shutdown of the unit are ensured.

2. The hydraulic pitch fault fast positioning and safe shutdown method according to claim 1, characterized in that the required pitch angle is a target instruction value issued by a master control PLC to a pitch PLC, the actual pitch angle is a cylinder displacement value measured by a displacement sensor, and is converted into the actual pitch angle through a nonlinear relationship and transmitted to the master control through CANopen communication.

3. The hydraulic variable-pitch fault rapid positioning and safe shutdown method according to claim 1, characterized in that the hydraulic variable-pitch control system valve block mainly comprises a proportional directional valve, an electromagnetic directional valve, a one-way valve and an overflow valve, wherein the electromagnetic directional valve adopts an electromagnetic valve with a signal feedback contact, and a master control PLC monitors the feedback signal and performs logic judgment.

4. The hydraulic variable pitch fault rapid positioning and safety shutdown method according to claim 3, characterized in that the electromagnetic directional valve block is normally open, the valve is closed when the electromagnetic valve coil is powered on, and the valve is opened when the electromagnetic valve coil is powered off; the switches respectively give signal feedback to the master control PLC system, NC represents normally closed, NO represents normally open.

5. The hydraulic variable pitch fault rapid positioning and safe shutdown method according to claim 3, characterized in that the shutdown mode comprises a controllable shutdown mode and an emergency shutdown mode, the controllable shutdown mode is that the unit issues a shutdown instruction through a master control PLC, a corresponding valve block executes an action and gives a required variable pitch rate, and the emergency shutdown is that the unit realizes feathering through the release of an energy accumulator.

6. The hydraulic pitch fault fast positioning and safe shutdown method according to claim 3, characterized in that the selective shutdown mode is judged according to the actual pitch angle, i.e. the given judgment threshold is 40 °, after fault positioning, whether the actual minimum pitch angle is greater than or equal to 40 ° is judged, if true, normal shutdown is executed for the first time; and after a certain time, it is determined whether the minimum pitch angle is 85 ° or more. If the actual maximum pitch angle is less than or equal to 40 degrees, when a fault is detected, the accumulator is emergently stopped for the unit safety.

7. The hydraulic variable pitch fault rapid positioning and safety shutdown method according to claim 3, characterized in that the fault valve block rapid determination and positioning needs to compare the difference of the accumulator pressure of the hydraulic circuit in order to eliminate non-valve block factors, if the difference between the value of the accumulator pressure sensor of the hydraulic station and the value of the accumulator pressure sensor of the actuator is less than or equal to a preset threshold value, it indicates that the pipeline or the check valve is working normally at the moment, the influence of the factor is eliminated, it is determined that the problem is a valve block problem, and the preset threshold value is selected from 5 to 10bar as required.

8. The hydraulic variable pitch fault rapid positioning and safe shutdown method according to claim 1, characterized in that the pressure sensor is an analog quantity signal 4-20 mA, and the corresponding pressure range is 0-400 bar.

9. The hydraulic pitch fault rapid positioning and safety shutdown method according to claim 1, characterized in that the master PLC module is a MC205 module using Bachman, and the pitch PLC module is a CPC210 module using Bachman.

Technical Field

The invention relates to the technical field of wind power generation, in particular to a method for quickly positioning a hydraulic variable propeller fault and safely stopping the hydraulic variable propeller.

Background

The variable pitch system is a key system of the fan, and the adjustment of the rotating speed and the power of the unit can be realized by adjusting the pitch angle and changing the aerodynamic characteristics of the blades. However, the variable pitch system is a system with higher failure rate in the unit operation. Because the impeller is located the tower section of thick bamboo top, at first need lock the impeller and adjust a suitable oar blade in order to satisfy the required operation condition of fortune dimension personnel when maintaining, lead to becoming the oar fault maintenance man-hour longer, the operation is complicated, and the operation skill that requires to fortune dimension personnel is high. Particularly for offshore units, due to poor maintainability, the stability and high reliability of a pitch control system and the quick and accurate fault positioning capability are ensured, so that the units can obtain higher availability.

Patent CN 202867086U provides a way to safely shut down a wind turbine. Usually, the main control system issues a shutdown instruction to the variable pitch system, however, when the main control system fails or is down, the shutdown instruction cannot be issued, and the over-speed or runaway situation is easy to occur. This patent provides an additional control unit driver, and voltage signal or communication signal and main shaft rotational speed signal through main control issue under the detection trouble condition can issue the shut down instruction through the control unit when communication signal interruption or detect the overspeed, has realized control system's redundant configuration, guarantees the safe shut down of unit. Patent CN 101975142 a also proposes a redundant pitch design. When special working conditions occur, the motor driver integrated in the bottom layer of the variable pitch control system judges the shutdown mode through judging the priorities of the reset mode, the bypass mode, the redundant feathering mode, the emergency feathering mode and the manual 5 special working condition modes, and the variable pitch motor driver drives the blades to feather. Patent CN 102828909A provides a safety protection method of blade receipts oar inefficacy formula, through monitoring rotational speed overspeed signal and change oar fault judgement to among the safety protection PLC, carries out the driftage action, increases the windward deviation of unit, reduces the impeller rotational speed of unit, improves the security of unit.

It can be seen from the above patent that the safe shutdown of the unit mainly adopts a redundant configuration mode or reduces the rotating speed of the impeller of the unit through a yaw action to inhibit the occurrence of an overspeed condition. There is no patent relating to a way of rapid diagnosis of a fault in a pitch system and a way of shutdown in the event of such a fault.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for quickly positioning the fault of a hydraulic variable propeller and safely stopping the hydraulic variable propeller.

The technical scheme adopted by the invention for solving the technical problems is as follows: a hydraulic variable propeller fault rapid positioning and safe shutdown method comprises the following steps: variable data acquisition, rapid judgment and positioning of a fault valve block and selection of a shutdown mode,

the variable data acquisition is that a master control PLC is connected with a variable pitch PLC through CANopen communication to realize communication control and variable data transmission, fault early warning and shutdown judgment, the variable pitch PLC is connected with an electromagnetic directional valve with feedback signals, a proportional directional valve, a pressure sensor and a displacement sensor, the signals of the two electromagnetic directional valves with the feedback signals and the three-position four-way proportional directional valve are transmitted to a finger control PLC through the variable pitch PLC to be used as control logic judgment, the pressure sensor is provided with two sensors for respectively monitoring the pressure of an energy accumulator of a hydraulic station and the pressure of an energy accumulator of an actuator, and the displacement sensor monitors a displacement value of a cylinder body to obtain an actual pitch angle;

the fault valve block is quickly judged and positioned to be the actual pitch angle of the unit, the pressure of the hydraulic station energy accumulator and the pressure of the actuator energy accumulator as the judgment conditions of the fault valve block, the on-off of the electromagnetic reversing valve with signal feedback can be fed back to the on-off signal feedback of the master control PLC, the running working state of the electromagnetic reversing valve is monitored, the control logic of the unit is to carry out program monitoring through the feedback DI of the electromagnetic reversing valve with the feedback signal and the DO output instruction of the electromagnetic reversing valve, and the corresponding fault judgment is executed by combining the required pitch angle and the actual pitch angle of the unit, so that the fault valve block is judged, and the fault point is accurately positioned;

after the shutdown mode is selected to locate the fault, the shutdown mode is switched by judging the size of the pitch angle, so that the safety and reliability of the shutdown of the unit are ensured.

Specifically, the required pitch angle is a target instruction value issued by the master control PLC to the pitch control PLC, and the actual pitch angle is a cylinder displacement value measured by the displacement sensor, and is converted into the actual pitch angle through a nonlinear relationship, and the actual pitch angle is transmitted to the master control PLC through CANopen communication.

Specifically, the hydraulic variable-pitch control system valve block mainly comprises a proportional directional valve, an electromagnetic directional valve, a one-way valve and an overflow valve, wherein the electromagnetic directional valve adopts an electromagnetic valve with a signal feedback contact, and a master control PLC monitors a feedback signal and carries out logic judgment.

Specifically, the electromagnetic directional valve block is normally open, the valve is closed when the electromagnetic valve coil is powered on, and the valve is opened when the electromagnetic valve coil is powered off; the switches respectively give signal feedback to the master control PLC system, NC represents normally closed, NO represents normally open.

Specifically, the shutdown mode comprises a controllable shutdown mode and an emergency shutdown mode, the controllable shutdown mode is that the unit issues a shutdown instruction through a master control PLC, a corresponding valve block executes actions and gives a required pitch variation rate, and the emergency shutdown mode is that the unit releases through an energy accumulator to realize feathering.

Specifically, the selected shutdown mode is judged according to the actual pitch angle, namely a given judgment threshold value is 40 degrees, after fault positioning, whether the actual minimum pitch angle is more than or equal to 40 degrees is judged, and if yes, normal shutdown is executed for the first time; and after a certain time, it is determined whether the minimum pitch angle is 85 ° or more. If the actual maximum pitch angle is less than or equal to 40 degrees, when a fault is detected, the accumulator is emergently stopped for the unit safety.

Specifically, the fault valve block is quickly judged and positioned, in order to eliminate factors other than the valve block, the pressure of an energy accumulator of a hydraulic circuit needs to be subjected to difference value comparison, if the difference value between the value of a pressure sensor of the energy accumulator of the hydraulic station and the value of a pressure sensor of an energy accumulator of an actuator is smaller than or equal to a preset threshold value, the fact that a pipeline or a one-way valve works normally at the moment is indicated, the influence of the factors is eliminated, the problem of the valve block is confirmed, and the preset threshold value is selected from 5-10 bar according to needs.

Specifically, the pressure sensor is an analog quantity signal of 4-20 mA, and the corresponding pressure range is 0-400 bar.

Specifically, the master control PLC module adopts a bherman MC205 module, and the pitch PLC module is a bachman CPC210 module.

The invention has the following beneficial effects:

according to the invention, based on the working conditions that the variable pitch system is easy to generate variable pitch asynchrony and pitch clamping and the like in the action process, the output and feedback information and the hydraulic pressure value of the valve block are judged by adopting two groups of electromagnetic directional valves with feedback signals, and the fault point of the variable pitch system is accurately judged through the variable pitch control logic of the variable pitch PLC and the master control PLC, so that the fault is accurately positioned; different shutdown modes are executed according to the actual pitch angle characteristics of the blade through monitoring different faults; the method reduces the maintenance difficulty of field workers, and improves the availability, power generation level and safety of the unit; an electromagnetic directional valve with a feedback signal is adopted to accurately judge a variable-pitch fault valve block; shutdown in different modes is executed through judgment of the fault valve block, so that the safety of the unit is improved; through the quick positioning failure, the work difficulty of on-site operation and maintenance personnel is reduced, the work efficiency is improved, and the availability of the unit is improved.

Drawings

FIG. 1 is a communication block diagram of a hydraulic pitch fault fast positioning and safety shutdown method;

FIG. 2 is a block diagram of a pitch hydraulic schematic;

FIG. 3 is a control implementation flow chart of a hydraulic pitch fault rapid positioning and safe shutdown method;

in the figure: 1-an oil temperature meter; 2, a motor; 3-a motor; 4-a first electromagnetic directional valve; 10-a second electromagnetic directional valve; 11-a third electromagnetic directional valve; 21-electromagnetic directional valve four; 5-a one-way valve I; 22-one-way valve II; 25-one-way valve III; 31-check valve four; 6, a first overflow valve; 12-overflow valve II; 23-overflow valve III; 7-a first pressure sensor; 13-a second pressure sensor; 8-hydraulic station accumulators; 9-actuator accumulator; 14-a first electromagnetic directional valve with a feedback signal; 16-a second electromagnetic directional valve with a feedback signal; 15-proportional solenoid valve; 17-a first throttling valve; 20-a throttle valve II; 24-throttle valve III; 26-throttle valve four; 18-a displacement sensor; 19-a piston cylinder; 27-a heat sink; 28-a heat exchanger; 29-a filter; 30-oil liquid; 32-cooling pump.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in further detail in the following clearly and completely with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1-3, a hydraulic variable-pitch fault rapid positioning and safe shutdown method comprises the following steps: the system comprises a variable data acquisition unit, a fault valve block quick judgment unit, a fault early warning unit and a shutdown selection unit, wherein the variable data acquisition unit is characterized in that a master control PLC is connected with a variable pitch PLC through CANopen communication to realize communication control and transmission of variable data, fault early warning and shutdown judgment, the variable pitch PLC is connected with an electromagnetic directional valve with feedback signals, a proportional directional valve, a pressure sensor and a displacement sensor, two electromagnetic directional valves with feedback signals and a three-position four-way proportional directional valve signal are transmitted to a finger control PLC through the variable pitch PLC to be used as control logic judgment, the pressure sensor is provided with two pressure monitoring hydraulic station energy accumulator pressure and actuator energy accumulator pressure, and the displacement sensor monitors a displacement value to obtain an actual pitch angle; the fault valve block is quickly judged and positioned to be the actual pitch angle of the unit, the pressure of the hydraulic station energy accumulator and the pressure of the actuator energy accumulator as the judgment conditions of the fault valve block, the on-off of the electromagnetic reversing valve with signal feedback can be fed back to the on-off signal feedback of the master control PLC, the running working state of the electromagnetic reversing valve is monitored, the control logic of the unit is to carry out program monitoring through the feedback DI of the electromagnetic reversing valve with the feedback signal and the DO output instruction of the electromagnetic reversing valve, and the corresponding fault judgment is executed by combining the required pitch angle and the actual pitch angle of the unit, so that the fault valve block is judged, and the fault point is accurately positioned; after the shutdown mode is selected to position the fault, the control method realizes the mode of outputting and feeding back signals by a PLC of a main control monitoring variable pitch system valve block module through judging the pitch, and realizes the quick positioning of the variable pitch fault according to the hydraulic variable pitch pressure signals and the control logic. And after the fault is positioned, different shutdown modes are given according to the actual pitch angle to realize safe shutdown.

As a further explanation of the above technical solution:

the master control system and the variable pitch system realize communication control and variable data transmission through CANopen. The variable pitch fault is transmitted to the master control PLC through CANopen communication, fault early warning and shutdown judgment are achieved, message heartbeat is monitored through master control, and communication fault detection is achieved. The master control PLC module adopts an MC205 module of Bachman, and the variable pitch PLC module is a CPC210 module of Bachman.

The current variable-pitch system performs variable-pitch control according to single-cylinder hydraulic variable pitch, and reference can be made to fig. 2, but the same control detection method is applicable to a double-cylinder or three-cylinder hydraulic variable-pitch control system.

The single-cylinder hydraulic variable-pitch control system valve block mainly comprises a proportional directional valve 15, a first electromagnetic directional valve 14/a first electromagnetic directional valve 16, a first check valve 5 and a first overflow valve 6, wherein the first electromagnetic directional valve 14/the first electromagnetic directional valve 16 adopt electromagnetic valves with signal feedback contacts, and a master control PLC monitors feedback signals and carries out logic judgment. The on-off of the electromagnetic valve with signal feedback can be fed back to the on-off signal feedback of the PLC system, and the running working state of the electromagnetic directional valve is monitored. When the electromagnetic directional valve is electrified and opened, the common line is communicated with the open signal line; when the electromagnetic directional valve is closed when power is off, the common line is communicated with the off signal line.

The electromagnetic directional valve is divided into a normally closed type and a normally open type, and the normally closed type: when the electromagnetic valve coil is electrified, the valve is opened, and when the electromagnetic valve coil is powered off, the valve is closed; the switches respectively give a signal feedback prompt to the system. Normally open type: the valve is closed when the electromagnetic valve coil is electrified, and is opened when the electromagnetic valve coil is powered off; the switch respectively gives a signal feedback to the system, and the electromagnetic valve block is normally open, NC represents normally closed, NO represents normally open.

The control logic of the unit is to perform program monitoring through a feedback DI of the electromagnetic valve with a feedback signal and a DO output instruction of the electromagnetic valve, and to perform corresponding fault judgment and shutdown mode judgment by combining the required pitch angle and the actual pitch angle of the unit.

The pressure of the hydraulic variable pitch system is detected by a pressure sensor and is monitored by a main control variable signal value. The pressure sensor is an analog quantity signal of 4-20 mA, and the corresponding pressure range is 0-400 bar. The required pitch angle is a target instruction value issued to the variable pitch PLC by the master control PLC, the actual pitch angle is a cylinder displacement value measured by the displacement sensor, and the actual pitch angle is converted into the actual pitch angle through a nonlinear relation and transmitted to the master control through CANopen communication.

The shutdown mode mainly comprises a controllable shutdown mode and an emergency shutdown mode. The controllable shutdown mode is that the unit issues a shutdown instruction through main control, and the corresponding valve block executes actions and gives a required variable pitch rate. The emergency shutdown realizes feathering for the unit through the release of the energy accumulator.

It should be noted that, in the method, it is assumed that a power failure condition does not occur in a pitch control system of the unit (at this time, the UPS cannot provide a backup power supply), and the unit performs an emergency shutdown in the power failure condition.

Judging according to the actual pitch angle by selecting a shutdown mode, namely giving a judgment threshold value of 40 degrees, after fault positioning, judging whether the actual minimum pitch angle is more than or equal to 40 degrees, and if so, executing normal shutdown for the first time; and after a certain time, it is determined whether the minimum pitch angle is 85 ° or more. If the actual maximum pitch angle is less than or equal to 40 degrees, when a fault is detected, the accumulator is emergently stopped for the unit safety. The fault valve block is quickly judged and positioned, in order to eliminate factors other than the valve block, the pressure of an energy accumulator of a hydraulic circuit needs to be subjected to difference value comparison, if the difference value between the value of a pressure sensor of the energy accumulator of the hydraulic station and the value of a pressure sensor of an energy accumulator of an actuator is smaller than or equal to a preset threshold value, the fact that a pipeline or a one-way valve works normally at the moment is indicated, the influence of the factors is eliminated, the problem of the valve block is confirmed, and the preset threshold value is selected from 5-10 bar according to needs.

As shown in fig. 2, a whole hydraulic pitch control schematic diagram is given, the motor and the motor are power devices of the whole system, and the pressure of the pitch actuator and the pressure of the hydraulic station are monitored, and when the pressure is smaller than a preset threshold value, a command for starting the pump station is issued by the master controller to start pressure building. When the variable pitch PLC monitors that the pressure value of the system is lower than the lower limit of the set threshold value of 210bar, the motor 2 drives the motor 3 to work, and oil returns to the oil tank 30 through the bypass electromagnetic directional valve I4, so that the functions of cleaning a pipeline and building pressure in no-load are mainly achieved. And after the no-load pressure is built for 2s, the first bypass electromagnetic directional valve 4 is electrified and sucked, and the pressure building of the actuator is started. The first electromagnetic directional valve 4 needs to be electrified in the pressure building process, the first electromagnetic directional valve 4 is a key valve body and is generally called as a bypass electromagnetic valve, and the managed flushing, the oil filtering and the temperature increasing can be realized under the condition that the first electromagnetic directional valve 4 is not electrified.

In the pressure building process of the machine set, the pressure building of the hydraulic station energy accumulator and the actuator energy accumulator is realized, and the pressure value can be monitored through the first pressure sensor 7 and the second pressure sensor 13.

When oil enters the variable-pitch actuating mechanism through the one-way valve 25, the control of the valve block needs to be realized by combining a control mode.

In the normal propeller opening process, all the electromagnetic valves are electrified, oil enters the rod cavity through the left position of the three-position four-way proportional reversing valve 15, and the hydraulic oil flows out of the rodless cavity and then returns to the oil tank 30 through the filter through the second electromagnetic reversing valve 16 with the feedback signal and the left position of the three-position four-way proportional reversing valve 15.

In the normal feathering process, all the electromagnetic valves are electrified, and oil enters the rodless cavity through the right positions of the two feedback signal electromagnetic reversing valves 14 and 16 and the three-position four-way proportional reversing valve 15; the rod cavity forms a differential circuit through a second one-way valve 22 to realize rapid feathering.

When the engine is in emergency shutdown, the actuator energy accumulator 9 acts at the moment, oil liquid realizes rodless cavity oil supply through the two electromagnetic reversing valves 10 and 11, and the oil liquid in the rod cavity flows into the oil tank 30 through the electromagnetic reversing valve IV 21, so that the emergency feathering function is realized.

It should be noted that, the adoption of two electromagnetic directional valves realizes redundant control, and ensures the shutdown safety of the unit. In addition, during the emergency stop process, the hydraulic station accumulator 8 can also provide auxiliary pressure oil supply to ensure the safe stop of the system.

As shown in fig. 3, a method for quickly positioning and protecting a variable pitch fault is provided, and a variable pitch action of a unit occurs in a starting process and above a rated wind speed, and at the moment, a variable pitch angle changes. When the unit pitch variation action occurs, the required value is issued to the pitch variation PLC through a CANopen bus according to the required pitch angle theta calculated by the main control algorithm, the movement of the hydraulic cylinder is realized through the action of the actuator valve body, the pitch variation action is realized, the displacement of the hydraulic cylinder is detected through the displacement sensor, and the displacement is converted into the actual pitch variation angle through nonlinear transformation.

A general variable pitch system is of a three-blade structure, and the pitch angle of three blades is defined as theta₁，θ₂，θ₃。

The three blade pitch angle data are transmitted to a main controller through a CANopen bus to be subjected to pairwise comparison analysis, and the maximum pitch angle theta is judged_max＝max{θ₁，θ₂，θ₃}。

After the maximum pitch angle is determined, the maximum pitch angle deviation Delta theta is determined_max＝{∣θ₁-θ₂∣,∣θ₁-θ₃∣θ₂-θ₃| making a judgment basis for subsequent unsynchronization of the paddle or jamming of the paddle. According to the deviation of the maximum pitch angle, the asynchronous condition of the pitch-changing actuating mechanism is shown, the asynchronous condition exists in the whole pitch-changing process, but the condition that the deviation is larger than a set threshold value does not occur. Deviation at maximum Pitch Angle Δ θ_maxIf the value is more than 2 degrees, the asynchronous condition of the actuating mechanism is indicated, and in order to further determine the reason of the asynchronous condition, the fault point is quickly positioned, and the variable pitch pipeline action valve block is judged.

The electromagnetic directional valves 14 and 16 with feedback signals have the same function, the proportional electromagnetic directional valve 15 is a voltage control valve, the voltage range is-10 to +10V, wherein, the valve body left-position action is between-10 to 0V, and the valve body right-position action is between 0 to + 10V. Considering the logic of the PLC, in the process of normally opening the propeller of the master control PLC system, all the electromagnetic valves are electrified, the normally open electromagnetic directional valves 14 and 16 with feedback signals are fed back to TRUE under the normal condition, the proportional electromagnetic valve outputs signals to TRUE, and FALSE is executed if the proportional electromagnetic valve does not respond to the output. For this purpose, the following four cases are possible:

the first condition is as follows: DO _15 ═ FALSE, DI _14 ═ TRUE, DI _16 ═ TRUE;

case two: DO _15, DI _14, DI _16, TRUE;

case three: DO _15 ═ TRUE, DI _14 ═ TRUE, DI _16 ═ FALSE;

case four: DO _15 ═ TRUE, DI _14 ═ FALSE, DI _16 ═ TRUE;

it should be noted that DO represents a digital output, and DI represents a digital input.

The first situation shows that the pitch-variable PLC module instruction has a problem, and the control logic does not issue a correct enabling signal, so that the proportional directional valve does not receive an effective action instruction, and pitch variation cannot be realized. At the moment, the fault belongs to the fault of the PLC module, and the logic fault judgment is carried out in the program through the non-action of the proportional valve.

The second case illustrates that the valve block realizes action, but the variable pitch angle still has deviation, which is a problem frequently existing in practice and needs to be analyzed according to auxiliary conditions.

It should be noted that, generally, the problem is that the oil has impurities to cause the reversing of the proportional reversing valve to be locked, or the oil has larger viscosity at lower temperature to easily cause response delay to cause the condition that the blades are not synchronous or the blades are locked.

The problems that the blades are not synchronous or are blocked due to normal feedback and output of the three valve blocks and the proportional directional valve 15 cannot be accurately positioned exist, and a pressure signal needs to be further verified. And (3) monitoring the pressure signal of the energy accumulator of the pitch-variable hydraulic station and the pressure signal of the energy accumulator of the pitch-variable actuator to determine whether the pressure difference value of the two signals is less than or equal to 10bar, and if so, continuing to judge.

It should be noted that, under normal conditions, the pressure value of the energy accumulator of the pitch hydraulic station is higher than that of the pitch actuator, because there is one on-way pressure loss and one-way valve opening pressure difference between the two, but the two pressures are basically consistent by default in a negligible range. If the pressure difference is higher than 10bar, it indicates that the one-way valve three 25 and the pipeline in which it is located have problems.

When the pressure difference value is less than or equal to 10bar, the oil supply loop of the unit is normal, and the problem point is that the proportional valve is required, so that the fault of the proportional electromagnetic directional valve 15 can be confirmed, and the proportional electromagnetic directional valve needs to be replaced or maintained and checked in time.

The third and fourth cases can directly determine the fault source according to the control signal, so that the fault valve block can be locked quickly.

After the fault is accurately located, a requirement needs to be made on the safe shutdown of the unit under the fault condition. The aerodynamic characteristics of the unit are greatly reduced when the actual pitch angle is more than 40 degrees, so that the situation of overspeed driving is avoided, and the aerodynamic characteristics are better when the actual pitch angle is less than 20 degrees, so that special attention needs to be paid to the safety protection of the unit. For this purpose, the machine group is divided into shutdown modes according to the required pitch angle.

Through accurate positioning of a fault device of the variable pitch system, the valve block is proved to have a fault or response delay. A so-called valve block failure includes not only a failure of the valve block to respond to an actual control command, but also a response time error of the valve block.

And after the fault is judged, judging according to the pitch angle of the actual unit. Under the condition that the pitch angle is large and the unit is relatively safe, whether the actual minimum pitch angle meets theta or not is judged_minAnd the angle is more than or equal to 40 degrees, and if the angle is more than or equal to 40 degrees, the normal shutdown operation is executed for the first time. If the minimum pitch angle of the unit in the normal shutdown mode can satisfy theta_minAnd the normal stop is completed at the moment, which indicates that the valve block can work, but the problem of slow response exists, and whether impurities exist or the influence of low temperature needs to be checked. If the minimum pitch angle cannot be met, the valve block is in fault, emergency shutdown is executed at the moment, and the energy accumulator acts to ensure that the unit is safely shut down.

Under the condition of small pitch angle, the aerodynamic characteristics of the unit are good, and whether the actual maximum pitch angle meets theta needs to be judged_maxAnd (4) being less than or equal to 40 degrees, and if the angle is up, directly executing emergency shutdown.

In the method, the fault module is judged to be stopped when the pitch angle is large (the pitch angle is more than or equal to 40 degrees), and the unit safety is mainly used when the pitch angle is small (the pitch angle is less than 40 degrees).

The present invention is not limited to the above embodiments, and any structural changes made under the teaching of the present invention shall fall within the scope of the present invention, which is similar or similar to the technical solutions of the present invention.

The techniques, shapes, and configurations not described in detail in the present invention are all known techniques.