An all-electric speed control system

Abstract

The application relates to a full-electric speed regulating system, a rotating speed sensor is arranged at a steam turbine and used for detecting the rotating speed of the steam turbine; a speed controller is connected with the rotating speed sensor and a servo driver, used for realizing closed-loop control of the rotating speed of the steam turbine and outputting a control instruction to the servo driver; a linear motor linear displacement sensor is connected with the servo driver, used for realizing position and speed feedback of a linear motor moving part; the linear motor moving part is connected with a regulating valve through a lever or direct connection, so that the position of the regulating valve is controlled; and the servo driver is used for realizing closed-loop control of the position and speed of the linear motor moving part. The application uses an electric actuator to replace a traditional hydraulic actuator, the original hydraulic system is omitted, the volume occupied by the speed regulating system is reduced, vibration and noise caused by a hydraulic oil pump, pipelines and other hydraulic systems are reduced, manufacturing difficulty and maintenance requirements are reduced. Meanwhile, the full-electric speed regulating system does not have electro-hydraulic signal conversion, and the control mode is more flexible.

Description

TECHNICAL FIELD

[0001] The present application relates to a steam turbine speed governing system, in particular to a full electric speed governing system for steam turbine. BACKGROUND

[0002] The steam turbine speed governing system is to generate a control signal according to the deviation between the control target instruction and the feedback value of the steam turbine speed, and to realize the opening and closing change of the regulating valve position through the action of the actuator on the regulating valve, so as to control the steam turbine flow rate and realize the regulation of the steam turbine speed or load.

[0003] The performance simulation of the steam turbine speed governing system has experienced the early mechanical speed governor, mechanical hydraulic speed governor, analog electric hydraulic speed governor, and the currently widely used digital electric hydraulic speed governor.

[0004] The mechanical speed governor uses centrifugal weight and other forms of mechanical components as the speed sensing mechanism, as shown in FIG. 1, and directly drives the load force of the regulating valve to realize the position control of the regulating valve through the force change generated by the speed change. Due to the limited energy of this speed governor, it can only drive a relatively small regulating valve, and the application range is limited. Figure 1

[0005] The mechanical hydraulic speed governor is an improvement on the basis of the mechanical speed governor, as shown in FIG. 2, which uses the amplification of the oil valve to drive the intermediate oil valve mechanism by the force generated by the mechanical speed sensing mechanism, and then changes the hydraulic oil entering the oil cylinder by the intermediate oil valve to finally drive the regulating valve to realize the position control by the hydraulic force. Since the mechanical hydraulic speed governor uses mechanical components as the speed feedback and setting, the control precision is poor, and the flexibility of the control mode is not high. Figure 2

[0006] The analog and digital electric hydraulic speed governing system is based on the mechanical hydraulic speed governor, as shown in FIG. 3, which uses electronic sensors and circuits to replace the mechanical speed feedback and setting mechanism. The deviation between the speed setting value and the feedback value is calculated by the electronic components to generate an electric control signal, and the electric signal is converted into a hydraulic driving signal by the electro-hydraulic servo valve with electro-hydraulic conversion function, and finally the position control of the regulating valve is realized by the hydraulic components such as oil cylinder. This method makes good use of the flexible and convenient characteristics of electronic control technology, but it still needs to convert the control signal of the electronic driver into a hydraulic control signal, which increases the intermediate conversion link, and the control precision and response of the system are subject to the electro-hydraulic conversion. In addition, the electric hydraulic speed governing system needs to be equipped with hydraulic equipment, and the system configuration is complex and difficult to maintain. Figure 3

[0007] ​​​The existing analog and digital electro-hydraulic speed regulation system makes good use of the flexible and convenient characteristics of electronic control technology, but it still needs to convert the control signal of the electronic driver into a hydraulic control signal, which increases the intermediate conversion link, and the control precision and response of the system are subject to the electro-hydraulic conversion. In addition, the electro-hydraulic speed regulation system needs to be equipped with hydraulic equipment, and the system configuration is complex and difficult to maintain SUMMARY

[0008] In order to realize high-precision simulation of the steam turbine speed regulation performance, verify the function and performance of the steam turbine regulation and control system, and reduce the test resource demand of the regulation and control system, the application provides a new full-electric speed regulation system.

[0009] In order to achieve the above-mentioned purpose, the technical scheme of the application is: a full-electric speed regulation system, comprising a speed regulation controller, a servo driver, a linear motor, and a rotating speed sensor, the rotating speed sensor is arranged at the steam turbine and is used for detecting the rotating speed of the steam turbine; the speed regulation controller is connected with the rotating speed sensor and the servo driver, and is used for realizing closed-loop control of the rotating speed of the steam turbine and outputting a control instruction to the servo driver; a linear displacement sensor of the linear motor is connected with the servo driver, and is used for realizing position and speed feedback of a moving part of the linear motor; the moving part of the linear motor is connected with the regulating valve through a lever or a direct connection, so as to realize control of the position of the regulating valve; and the servo driver is used for realizing closed-loop control of the position and speed of the moving part of the linear motor.

[0010] Further, the rotating speed sensor adopts a Hall sensor, the change of the magnetic field of the rotating speed sensor caused by the rotating speed gear rotating with the steam turbine is utilized to make the rotating speed sensor output a square wave pulse signal to the speed regulation controller, and the speed regulation controller calculates the rotating speed by recording the frequency and quantity of the pulse.

[0011] Further, the speed regulation controller adopts an embedded programmable logic controller, realizes an execution cycle of 5 ms at the shortest, integrates the input of the pulse signal, the input of the current signal, the input of the switching value signal, and the output interface, collects the rotating speed and power signals of the steam turbine in real time, and adjusts and outputs the valve position control instruction of the steam turbine through a programmable logic algorithm, simultaneously, the speed regulation controller increases the thrust control output, outputs the thrust deviation adjustment instruction of the transient state condition through judging the transient state condition of the steam turbine, realizes the control enhancement of the thrust of the linear motor in the dynamic state, and enhances the response to the transient state condition.

[0012] Further, the speed regulation controller has a network communication interface, is in communication connection with an upper computer, and has the functions of monitoring and data storage realized based on the upper computer software.

[0013] Further, the servo driver comprises a control component and a power device, the control component adopts a high-performance DSP controller hardware, adopts an outer loop and an inner loop control loop, the outer loop control loop comprises a position loop and a speed loop, target values of the inner loop thrust control are generated according to the feedback and setting of the position and the speed, the inner loop control loop uses a space vector direct thrust control algorithm, control signals of frequency switching are generated according to the instruction generated by the outer loop control loop and the transient state working condition thrust deviation adjustment instruction input from the speed controller, and the power device realizes the conversion process of AC-DC-AC according to the frequency switching signals generated by the control component, so that the frequency and voltage control of the linear motor power supply is realized.

[0014] Further, the servo driver generates the control signals of SVPWM to output three-phase symmetrical sinusoidal currents according to the thrust control algorithm, under the action of the currents, the linear motor stator generates a traveling wave magnetic field, the magnetic field interacts with the permanent magnet magnetic field on the linear motor rotor to generate electromagnetic thrust, when the stator component of the linear motor is fixed, the rotor of the linear motor generates displacement under the action of the electromagnetic force.

[0015] Further, the linear motor adopts a water cooling heat dissipation mode, and cooling water is provided outside to realize linear motor stator cooling through a water cooling pipe.

[0016] Further, the stator of the linear motor adopts a double-sided structure, which is used for offsetting magnetic pull, reducing the strength requirement of the rotor support platform, reducing the structural weight of the rotor component, improving the response characteristics of the rotor, improving the power density, meeting the output thrust index, and reducing the size of the linear motor.

[0017] Further, the stator winding of the linear motor adopts an upper and lower laminated form, which can enhance the magnetic flux density and improve the power density, and the stator core yoke cooling mode is adopted, the water cooling pipe adopts a U-shaped structure embedded in the core inside, which is used for improving the heat dissipation efficiency and meeting the heat dissipation requirement of the high-power density linear motor.

[0018] Further, the rotor component of the linear motor adopts a permanent magnet pole encapsulated by epoxy resin, and a T-shaped aluminum alloy frame is additionally arranged for fixation and connection with a guide rail, the guide rail is used for guiding the linear displacement of the rotor, and a non-contact linear displacement sensor is integrated in the guide rail to realize sensing detection on the position of the rotor.

[0019] The beneficial effects of the present application are as follows:

[0020] The full electric speed regulation system of the present application uses an electric actuator to replace the traditional hydraulic actuator, the original hydraulic system is omitted, the volume occupied by the speed regulation system is reduced, the vibration and noise caused by the hydraulic oil pump, pipeline and other hydraulic systems are reduced, the manufacturing difficulty and maintenance requirement are reduced. Meanwhile, the full electric speed regulation system does not exist electro-hydraulic signal conversion, and the control mode is more flexible. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 This is a schematic diagram of the mechanical speed control system.

[0022] Figure 2 This is a schematic diagram of the mechanical-hydraulic speed control system.

[0023] Figure 3 This is a schematic diagram of the electro-hydraulic speed control system.

[0024] Figure 4 This is a schematic diagram of the all-electric speed control system of the present invention;

[0025] Figure 5 This is a schematic diagram of the control loop of the all-electric speed regulation system of the present invention;

[0026] Figure 6 This is a schematic diagram of a linear motor structure;

[0027] Figure 7 This is a structural diagram of a double-sided linear motor;

[0028] Figure 8 This is a structural diagram of the mover of a linear motor. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] like Figure 4 As shown in Figure 5, the present invention provides a novel all-electric speed control system, which consists of a speed sensor 10, a speed controller 11, a servo driver 12, a linear motor 14, etc.

[0031] The speed sensor 10 is used to detect the turbine speed. The speed controller 11 realizes closed-loop control of the turbine speed and outputs control commands to the servo driver 12. The linear displacement sensor 13 of the linear motor realizes the position and speed feedback of the linear motor's mover component. The servo driver 12 realizes closed-loop control of the position and speed of the linear motor mover through three-loop control: position loop, speed loop, and thrust loop. The thrust control algorithm generates an SVPWM control signal, causing the servo driver to output a three-phase symmetrical sinusoidal current. Under the action of the current, the stator of the linear motor generates a traveling wave magnetic field. This magnetic field interacts with the magnetic field of the permanent magnet on the mover of the linear motor, generating electromagnetic thrust. When the stator component of the linear motor 14 is fixed, the mover of the linear motor 14 is displaced under the action of electromagnetic force. The mover of the linear motor 14 is connected to the regulating valve 15 through a lever or direct connection, thereby realizing the control of the regulating valve position.

[0032] The linear motor 14 adopts a water-cooled heat dissipation method, with external cooling water supplied through water-cooling pipes to cool the stator of the linear motor.

[0033] The rotation speed sensor 10 adopts a Hall sensor, and utilizes the change of the magnetic field of the rotation speed sensor caused by the speed measuring gear when the turbine rotates to make the rotation speed sensor 10 output a square wave pulse signal. The speed control device 11 calculates the rotation speed by recording the frequency and quantity of the pulse. The system is configured with three rotation speed sensors 10 for redundancy optimization. In case of failure of any two rotation speed sensors 10, the system can continue to operate.

[0034] The speed control device 11 adopts an embedded programmable logic controller, which can realize an execution cycle of 5 ms at the shortest. The controller integrates pulse signal input, current signal, switching value signal and other types of input and output interfaces, can collect turbine rotation speed, power and other signals in real time, and adjust and output turbine valve position control instructions through programmable logic algorithm. Meanwhile, the speed control device 11 increases thrust control output, outputs thrust deviation adjustment instructions of transient working conditions by judging the transient working conditions of the turbine, and realizes the control enhancement of the linear motor thrust and the response to transient working conditions. The adjustment control device 11 has a network communication interface, which can be connected to an upper computer. The monitoring, data storage and other functions are realized based on the upper computer software.

[0035] The servo driver 12 mainly includes a control component and a power device. The control component is based on a high-performance DSP controller hardware, mainly including a DSP, a current and voltage detection protection circuit, a driving level protection circuit, a communication circuit, a display module and the like. The controller adopts a three-loop control strategy. The outer loop includes a position loop and a speed loop. The target value of the inner loop thrust control is generated according to the feedback and setting of the position and speed. The innermost loop thrust control loop uses a space vector direct thrust control algorithm. According to the instruction generated by the outer loop control and the transient working condition thrust deviation adjustment instruction input from the adjustment control device, the frequency switching control signal is generated. The power device mainly includes a rectifier circuit, a filter circuit and an inverter circuit. According to the frequency switching signal generated by the control component, the space vector direct thrust control algorithm realizes the conversion process of AC-DC-AC, and realizes the frequency and voltage control of the linear motor power supply.

[0036] Since the turbine speed regulating actuator has the requirements of large thrust, high frequency response and small size, the linear motor as the actuator adopts a flat plate type permanent magnet synchronous motor structure, as shown in Figure 6 , which mainly consists of a stator 1 and a rotor 2.

[0037] The stator 1 adopts a double-sided structure (see Figure 7On the one hand, the magnetic pull can be counteracted, the strength requirement of the mover support platform is reduced, the structural weight of the mover component is reduced, and the response characteristics of the mover are improved; on the other hand, the double-sided structure can improve the power density, meet the output thrust index, and reduce the size of the linear motor. The stator winding adopts an upper and lower laminated form, further enhancing the magnetic flux density and improving the power density. The stator core yoke is water-cooled, and the water-cooled pipe is embedded in the core in a U-shaped structure to improve the heat dissipation efficiency and meet the heat dissipation requirements of the high-power density linear motor.

[0038] To meet the frequency response index requirements, the mover component adopts a lightweight design, as shown in Figure 8 The back iron used to fix the permanent magnet 3 in the conventional structure is cancelled, the permanent magnet pole is encapsulated with epoxy resin, an additional "T" shaped aluminum alloy frame 4 is used for fixation, and the frame is connected with the guide rail for guiding the linear displacement of the mover. The non-contact linear displacement sensor is integrated in the guide rail to realize the sensing and detection of the position of the mover. Compared with the conventional mover structure with back iron, the weight of the mover structure can be reduced by more than 2 / 3. The structure with the same electromagnetic performance can improve the acceleration of the mover by more than 2 / 3.

Claims

1. An all-electric speed control system, characterized by: The speed controller, servo driver, linear motor and rotating speed sensor are included, the rotating speed sensor is arranged at the steam turbine and is used for detecting the rotating speed of the steam turbine; the speed controller is connected with the rotating speed sensor and the servo driver and is used for realizing closed loop control of the rotating speed of the steam turbine and outputting control instructions to the servo driver; the linear displacement sensor of the linear motor is connected with the servo driver and is used for realizing position and speed feedback of the moving part of the linear motor; the moving part of the linear motor is connected with the regulating valve through a lever or direct connection, so as to realize control of the position of the regulating valve; the servo driver is used for realizing closed loop control of the position and speed of the moving part of the linear motor. The speed controller adopts an embedded programmable logic controller, realizes an execution cycle of 5 ms at the shortest, integrates pulse signal input, current signal, switch value signal input and output interfaces, collects steam turbine rotating speed and power signals in real time, and adjusts and outputs steam turbine valve position control instructions through programmable logic algorithms; meanwhile, the speed controller increases thrust control output, outputs thrust deviation adjustment instructions of transient working conditions by judging the transient working conditions of the steam turbine, realizes control enhancement of the thrust of the linear motor in the dynamic state, and enhances the response to transient working conditions; the stator of the linear motor adopts a double-sided structure, which is used for offsetting magnetic pull, reducing the strength requirement of the moving part support platform, reducing the structural weight of the moving part, improving the response characteristics of the moving part, improving the power density, meeting the output thrust index, and reducing the size of the linear motor; the stator winding of the linear motor adopts an upper and lower laminated form, which can enhance the magnetic flux density and improve the power density; the stator core yoke is cooled by a cooling method, a U-shaped water cooling pipe is embedded in the core for improving the heat dissipation efficiency and meeting the heat dissipation requirement of the high power density linear motor; the moving part of the linear motor adopts a permanent magnet pole encapsulated by epoxy resin, and a "T" shaped aluminum alloy frame is additionally provided for fixation and connection with the guide rail, the guide rail is used for guiding the linear displacement of the moving part, and a non-contact linear displacement sensor is integrated in the guide rail to realize sensing and detection of the position of the moving part.

2. The all-electrical servo system of claim 1, wherein: The rotating speed sensor adopts a Hall type sensor, the rotating speed sensor outputs a square wave pulse signal to the speed controller by using the change of the magnetic field of the rotating speed sensor caused by the rotating speed gear when the steam turbine rotates, and the speed controller calculates the rotating speed by recording the frequency and quantity of the pulses.

3. The all-electrical servo system of claim 1, wherein: The servo driver includes a control component and a power device, the control component adopts a high-performance DSP controller hardware, adopts an outer loop and an inner loop control ring, the outer loop control ring includes a position loop and a speed loop, the outer loop control ring generates a target value of the inner loop thrust control according to the feedback and setting of the position and speed, the inner loop control ring uses a space vector direct thrust control algorithm, generates a frequency switch control signal according to the instruction generated by the outer loop control ring and the transient working condition thrust deviation adjustment instruction input from the speed controller; the power device realizes an AC-DC-AC conversion process according to the frequency switch signal generated by the control component, and realizes frequency and voltage control of the linear motor power supply.

4. The all-electrical servo system of claim 3, wherein: The servo driver generates the control signal output of the SVPWM according to the thrust control algorithm, three-phase symmetrical sinusoidal current, under the action of the current, the stator of the linear motor generates the traveling wave magnetic field, the magnetic field interacts with the permanent magnet magnetic field on the rotor of the linear motor, and the electromagnetic thrust is generated.

5. The all-electrical servo system of claim 1, wherein: The linear motor adopts a water cooling heat dissipation mode, and external cooling water passes through a water cooling pipe to cool the stator of the linear motor.

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