Steam turbine generator unit double-layer rack vibration active control system based on feedforward compensation

Abstract

The invention relates to a steam turbine generator unit double-layer rack vibration active control system based on feed-forward compensation, which can monitor the vibration of a vibration steam turbine generator unit in real time and construct closed-loop feedback control based on a piezoelectric element and a spring damper to realize active and passive vibration control. Disturbance impact force possibly generated by a steam turbine generator unit on an upper-layer rack is observed and estimated in real time, a feed-forward link is constructed based on an observation and estimation result and serves as an equivalent input end to be added into a vibration control unit, and therefore feed-forward compensation of the vibration control unit is achieved. Therefore, the system can pre-judge the state of the system in advance under the condition that different types of disturbance impact are coupled, so that the control performance is better ensured.

Description

Technical Field

[0001] The invention relates to the technical field of vibration control, and in particular to a double-layer frame active vibration control system of a steam turbine generator set based on feedforward compensation. Background Art

[0002] At present, the vibration control related to steam turbine generator sets mainly adopts passive vibration reduction methods such as damping patches, and active control of the excitation characteristics of the vibration steam turbine generator sets has not yet been carried out.

[0003] In the past, vibration monitoring of steam turbine generator sets was only used for data analysis and vibration control performance evaluation. The vibration observation algorithm was not effectively iterated based on the vibration monitoring data, resulting in unclear vibration characteristics generated by the excitation source and difficulty in effective vibration suppression. Summary of the invention

[0004] To address the above problems, a double-layer frame active vibration control system for a steam turbine generator set based on feedforward compensation is proposed. It can effectively observe the vibration characteristics generated by the excitation source of the steam turbine generator set and perform active control based on the observation results, thereby effectively reducing the vibration energy transmitted from the vibration excitation source of the steam turbine generator set to the raft through the frame.

[0005] The technical solution of the present invention is: a double-layer frame active vibration control system for a steam turbine generator set based on feedforward compensation,

[0006] It includes an upper frame, a lower frame, a spring damper, a piezoelectric element, a vibration sensor, a displacement sensor, a vibration control unit, an H-type chopper circuit, a power amplifier and a power device;

[0007] The steam turbine generator set is placed on the upper frame, and an array of spring dampers and piezoelectric elements are set between the upper frame and the lower frame. The lower frame is placed on the raft frame on the ground through a vibration isolator. The vibration sensor and the displacement sensor detect the vibration signal and displacement signal of the upper frame and send them to the vibration control unit. The vibration control unit outputs a control voltage signal, which is converted into a PWM pulse through an H-type chopper circuit, and then a driving signal is formed through a power amplifier to the power device after filtering and noise reduction. The power device is controlled to be on and off to pass the driving control current to the piezoelectric element, so as to suppress the disturbance impact generated by the upper frame of the steam turbine generator set in real time; the vibration control unit includes a DOB disturbance observer, a low-pass filter and an LQR linear quadratic regulator, which are used for analyzing and processing vibration signals and calculating control current.

[0008] Preferably, the spring damper realizes passive control of vibration, and the vibration control unit performs calculations and outputs control voltage to both ends of the piezoelectric element, thereby realizing active control of the piezoelectric element generating corresponding control force vibration and disturbance impact force.

[0009] Preferably, the DOB disturbance observer compares the displacement signal and vibration signal obtained by the actual sensor output with the signal output by the established upper frame transfer function, and adds a vibration control unit as an equivalent input terminal as feedforward compensation of the vibration control unit, thereby realizing real-time suppression of disturbance impact force and vibration.

[0010] Preferably, the vibration sensor measures the vibration signal of the upper frame, processes the signal through a low-pass filter, and observes the disturbance impact of the steam turbine generator set based on the DOB disturbance observer. The upper frame transfer function is corrected according to the observation result and the control quantity is output based on the optimal control law. In addition, considering that the observation performance of the DOB disturbance observer is closely related to the parameter selection of the low-pass filter, the parameters of the low-pass filter are actually debugged. In addition, considering the control performance, the LQR linear quadratic regulator optimizes the parameters of the optimal control law to achieve the purpose of optimal control.

[0011] Preferably, in order to meet the requirements of physical feasibility, the low-pass filter is designed to ensure that the equivalent order of the Laplace transform of the low-pass filter is greater than or equal to the relative order of the transfer function of the upper rack; the time constant of the low-pass filter is selected by comprehensively analyzing the fitting speed, anti-interference ability and high-frequency noise suppression performance of the interference observation.

[0012] Preferably, the optimal control law is obtained by:

[0013] The upper frame dynamics model is linearized to obtain the corresponding upper frame transfer function

[0014] In the formula, the values ​​of A, B, C, D, and E are determined according to the system parameters;

[0015] The displacement signal and vibration signal obtained by the actual sensor output are compared with the signal output by the system transfer function, and added to the vibration control unit as an equivalent control input u;

[0016] Considering the continuity of vibration excitation on the upper frame, the corresponding spatial state equation is established based on the motion state of the upper frame:

[0017]

[0018] According to the state space equation, X, Y, and u are defined as the system state matrix, vibration output vector, and control input vector. The quadratic performance index functional of the upper frame vibration isolation system is as follows:

[0019]

[0020] Where X' is the system state vector, u' is the control vector, t is the time, and the weighting matrix R = R T >0, Q=Q T ≥0, according to the matrix Riccati equation corresponding to the LQR linear quadratic regulator control problem, it is found that when the upper rack motion model is objective, there is a unique positive definite symmetric matrix P, so the optimal control law is as shown below:

[0021] u(t)=-R -1 B T PX(t) (5)

[0022] In the formula, B is the pre-coefficient of the control vector u, and P is a constant matrix determined according to the system state. The output control voltage drives the power amplifier to form a control current for the piezoelectric element, tracks the state in real time, and observes the disturbance impact of the steam turbine generator set on the frame. Based on the observation results, a feedforward link is constructed to finally form a closed-loop control loop.

[0023] The beneficial effects of the present invention are as follows: the active vibration control system of the double-layer frame of the steam turbine generator set based on feedforward compensation of the present invention can monitor the vibration of the vibrating steam turbine generator set in real time, and construct a closed-loop feedback control based on piezoelectric elements and spring dampers, thereby realizing active and passive control of vibration; the disturbance impact force that the steam turbine generator set may generate on the upper frame is observed and estimated in real time, a feedforward link is constructed based on the observation and estimation results, and it is added to the vibration control unit as an equivalent input terminal, thereby realizing feedforward compensation of the vibration control unit, so that the system can predict the system state in advance when different types of disturbance impacts are coupled, thereby better ensuring the control performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural block diagram of the active control system for vibration of a double-layer frame of a steam turbine generator set based on feedforward compensation of the present invention;

[0025] Figure 2 This is the overall control logic diagram of the present invention. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0027] like Figure 1 , 2The structure block diagram and control logic diagram of the double-layer frame vibration active control system of the steam turbine generator set designed by the present invention based on feedforward compensation are shown. The system includes an upper frame, a lower frame, a spring damper, a piezoelectric element, a vibration sensor, a displacement sensor, a vibration control unit, an H-type chopper circuit, a power amplifier, a power device, a support capacitor and matching circuit elements. The steam turbine generator set is placed on the upper frame, and an array of spring dampers and piezoelectric elements are arranged between the upper frame and the lower frame. The lower frame is placed on a raft frame on the ground through a vibration isolator. The vibration sensor and the displacement sensor detect the vibration signal and displacement signal of the upper frame and send them to the vibration control unit. The vibration control unit outputs a control voltage signal, which is converted into a PWM pulse through the H-type chopper circuit, and then a drive signal is formed to the power device through the power amplifier after filtering and noise reduction. The power device is controlled to be on and off to pass the drive control current to the piezoelectric element, and the disturbance impact generated by the upper frame of the steam turbine generator set is suppressed in real time. The function of the support capacitor and the matching circuit elements is mainly to withstand the reverse voltage and protect the entire circuit from the influence of voltage mutation. The vibration control unit includes a DOB disturbance observer, a low-pass filter and an LQR linear quadratic regulator, which are used for analyzing and processing vibration signals and calculating control current.

[0028] In the design process of DOB disturbance observer, the upper frame dynamic model is first linearized to obtain the corresponding upper frame transfer function.

[0029]

[0030] In the formula, the values ​​of A, B, C, D, and E are determined according to system parameters.

[0031] Secondly, the displacement signal and vibration signal obtained by the actual sensor output are compared with the signal output by the system transfer function, and added to the vibration control unit as an equivalent input terminal, so as to realize feedforward compensation in the vibration control unit, and then realize real-time suppression of disturbance impact force and vibration.

[0032] The active vibration control system of the double-layer frame of the steam turbine generator set based on feedforward compensation realizes passive vibration control through the spring damper on the one hand, and outputs the control voltage V to both ends of the piezoelectric element through calculation on the other hand, so that the piezoelectric element generates the corresponding control force F pActive control of vibration and disturbance impact force. The performance of the DOB disturbance observer depends on the design of the low-pass filter. In order to obtain better disturbance force observation performance, the design of the low-pass filter requires the selection of the filter structure and time constant. The Laplace transform of the low-pass filter is defined as L(s), τ is the filter time constant, and in order to meet the requirements of physical feasibility, the equivalent order of L(s) is guaranteed to be greater than or equal to the relative order of the upper rack transfer function. L(s) is defined as shown in the following formula:

[0033] L(s)=s 2 τ 2 +2sτ+1 (2)

[0034] Among them, by comprehensively considering the fitting speed of interference observation, anti-interference ability and high-frequency noise suppression performance, the time constant τ is taken as 0.01, and the sampling frequency of the control unit is preferably selected as 1000Hz.

[0035] Considering the persistence of vibration excitation on the upper frame, the design of infinite-time LQR linear quadratic regulator is obviously more meaningful. The corresponding spatial state equation is established based on the motion state of the upper frame.

[0036]

[0037] Thus, the relevant coefficient matrices A, B, C, and D can be obtained. The automatic control theory can prove that the upper frame motion model is controllable and observable. And according to the state space equation, X, Y, and u are defined as the system state matrix, vibration output vector, and control input vector. The quadratic performance index functional of the upper frame vibration isolation system is as follows:

[0038]

[0039] Where X' is the system state vector, u' is the control vector, t is the time, and the weighting matrix R = R T >0, Q=Q T ≥0. According to the matrix Riccati equation corresponding to the LQR linear quadratic regulator control problem, it can be obtained that when the upper rack motion model is objective, there is a unique positive definite symmetric matrix P, so the optimal control law is as shown in the following formula:

[0040] u(t)=-R -1 B T PX(t) (5)

[0041] In the formula, B is the pre-coefficient of the control vector u, and P is a constant matrix (determined according to the system state). The output control voltage drives the power amplifier to form a control current for the piezoelectric element, tracks the state in real time, and observes the disturbance impact of the steam turbine generator set on the frame. Based on the observation results, a feedforward link is constructed to finally form a closed-loop control loop.

[0042] The vibration control unit hardware itself has a DC-110V power interface. The DC-110V power supply is used to power it, and after voltage reduction, it powers the circuit board, which in turn provides power for the circuit board for signal processing and control quantity calculation, and at the same time powers the piezoelectric element main circuit.

[0043] The vibration sensor measures the vibration signal of the upper frame, and the signal is processed by the low-pass filter. At the same time, the disturbance impact of the steam turbine generator set is observed based on the DOB disturbance observer. The upper frame transfer function is corrected according to the observation results and the control quantity output is based on the formula (5). In addition, considering that the observation performance of the DOB disturbance observer is closely related to the parameter selection of the low-pass filter, it is necessary to actually debug the parameters of the low-pass filter to improve the reliability of the observation results. In addition, considering the control performance, the non-unique matrix R and Q in the index functional (shown in formula (4)) can be debugged in real time, or the genetic algorithm, gradient descent method, etc. can be used to continue to optimize the parameters, so as to achieve the purpose of optimal control.

[0044] In summary, the present invention constructs active and passive vibration control and vibration isolation based on piezoelectric elements and spring dampers based on a feedforward compensation method, wherein the vibration control unit has signal receiving, processing and transmission functions, so that the system has the characteristics of active adjustment according to the current suspension and vibration conditions in real time, with high control accuracy and reliability.

[0045] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A double-layer frame active vibration control system for a steam turbine generator set based on feedforward compensation, characterized in that: It includes an upper frame, a lower frame, a spring damper, a piezoelectric element, a vibration sensor, a displacement sensor, a vibration control unit, an H-type chopper circuit, a power amplifier and a power device; The steam turbine generator set is placed on the upper frame, and an array of spring dampers and piezoelectric elements are set between the upper frame and the lower frame. The lower frame is placed on the raft frame on the ground through a vibration isolator. The vibration sensor and the displacement sensor detect the vibration signal and displacement signal of the upper frame and send them to the vibration control unit. The vibration control unit outputs a control voltage signal, which is converted into a PWM pulse through an H-type chopper circuit, and then a driving signal is formed through a power amplifier to the power device after filtering and noise reduction. The power device is controlled to be on and off to pass the driving control current to the piezoelectric element, so as to suppress the disturbance impact generated by the upper frame of the steam turbine generator set in real time; the vibration control unit includes a DOB disturbance observer, a low-pass filter and an LQR linear quadratic regulator, which are used for analyzing and processing vibration signals and calculating control current.

2. According to the feedforward compensation based active vibration control system for double-layer frame of steam turbine generator set in claim 1, it is characterized in that: The spring damper realizes passive control of vibration, and the vibration control unit performs calculations and outputs control voltage to both ends of the piezoelectric element, thereby realizing active control of the corresponding control force vibration and disturbance impact force generated by the piezoelectric element.

3. The double-layer frame active vibration control system of a steam turbine generator set based on feedforward compensation according to claim 1 or 2, characterized in that: The DOB disturbance observer compares the displacement signal and vibration signal obtained by the actual sensor output with the signal output by the established upper frame transfer function, and adds the vibration control unit as an equivalent input terminal as feedforward compensation of the vibration control unit, thereby realizing real-time suppression of disturbance impact force and vibration.

4. The double-layer frame active vibration control system of a steam turbine generator set based on feedforward compensation according to claim 3 is characterized in that: The vibration sensor measures the vibration signal of the upper frame, processes the signal through a low-pass filter, and observes the disturbance impact of the steam turbine generator set based on the DOB disturbance observer. The upper frame transfer function is corrected according to the observation result and the control quantity is output based on the optimal control law. In addition, considering that the observation performance of the DOB disturbance observer is closely related to the parameter selection of the low-pass filter, the parameters of the low-pass filter are actually debugged. In addition, considering the control performance, the LQR linear quadratic regulator optimizes the parameters of the optimal control law to achieve the purpose of optimal control.

5. The double-layer frame active vibration control system of a steam turbine generator set based on feedforward compensation according to claim 4 is characterized in that: In order to meet the requirements of physical feasibility and ensure that the equivalent order of the Laplace transform of the low-pass filter is greater than or equal to the relative order of the transfer function of the upper rack, the structure of the low-pass filter is designed; the time constant of the low-pass filter is selected by comprehensively considering the fitting speed, anti-interference ability and high-frequency noise suppression performance of the interference observation.

6. The double-layer frame active vibration control system of a steam turbine generator set based on feedforward compensation according to claim 4 is characterized in that: The optimal control law is obtained by: The upper frame dynamics model is linearized to obtain the corresponding upper frame transfer function In the formula, the values ​​of A, B, C, D, and E are determined according to the system parameters; The displacement signal and vibration signal obtained by the actual sensor output are compared with the signal output by the system transfer function, and added to the vibration control unit as an equivalent control input u; Considering the persistence of vibration excitation on the upper frame, the corresponding spatial state equation is established based on the motion state of the upper frame: According to the state space equation, X, Y, and u are defined as the system state matrix, vibration output vector, and control input vector. The quadratic performance index functional of the upper frame vibration isolation system is as follows: Where X' is the system state vector, u' is the control vector, t is the time, and the weighting matrix R = R T >0, Q=Q T ≥0, according to the matrix Riccati equation corresponding to the LQR linear quadratic regulator control problem, it is found that when the upper rack motion model is objective, there is a unique positive definite symmetric matrix P, so the optimal control law is as shown below: u(t)=-R -1 B T PX(t) (5) In the formula, B is the pre-coefficient of the control vector u, and P is a constant matrix determined according to the system state. The output control voltage drives the power amplifier to form a control current for the piezoelectric element, tracks the state in real time, and observes the disturbance impact of the steam turbine generator set on the frame. Based on the observation results, a feedforward link is constructed to finally form a closed-loop control loop.

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