A filtering device

Abstract

The present invention discloses a filtering device, comprising: a filtering unit, a steady-state error acquisition unit and a steady-state error correction unit; the input end of the filtering unit and the first input end of the steady-state error acquisition unit are respectively connected to the signal input end; the output end of the filtering unit is respectively connected to the second input end of the steady-state error acquisition unit and the first input end of the steady-state error correction unit, and the output end of the steady-state error acquisition unit is connected to the second input end of the steady-state error correction unit; the output end of the steady-state error correction unit is a signal output end; the steady-state error acquisition unit is used to acquire the input signal and output signal of the filtering unit, and obtain a steady-state error signal according to the input signal and the output signal; the steady-state error correction unit is used to linearly superimpose the steady-state error signal and the output signal of the filtering unit to obtain a correction signal. The present invention can eliminate the steady-state error between the output signal and the input signal of the fastest filter.

Description

Technical Field

[0001] The invention relates to the technical field of industrial process control, and in particular to a filtering device. Background Art

[0002] At present, the proportional-integral-derivative controller (PID) has been widely used in the field of industrial process control, promoting the formation of huge industrial productivity. PID is mature in industrial control engineering applications and perfect in theoretical refinement. The improvement of PID theory has a huge driving force on the entire control science. From the perspective of observation, the P action, I action, and D action in PID represent the three basic observation mechanisms in feedback control, specifically the current observation mechanism of the P action, the constant observation mechanism of the I action, and the advance observation mechanism of the D action. From the special method of constructing the I action and the D action, the I action and the D action are based on the first order inertial filter (FOIF). FOIF is a typical exponential tracking filter, so the I action and the D action represent an exponential constant observer and an exponential advance observer, so PID control implements an exponential control mechanism.

[0003] The existing filtering device uses the fastest tracking filter to construct the fastest controller to break through the exponential control mechanism of PID control. However, the existing fastest tracking filter has the problem of steady-state error. What is more serious is that the fastest integrator constructed using the fastest tracking filter has the problem of cumulative amplification of steady-state error, which limits the application of the fastest tracking filter. Summary of the invention

[0004] The present invention provides a filtering device to solve the technical problem of steady-state error existing in the existing filtering device.

[0005] An embodiment of the present invention provides a filtering device, comprising:

[0006] A filtering unit, a steady-state error acquisition unit and a steady-state error correction unit;

[0007] The input end of the filtering unit and the first input end of the steady-state error acquisition unit are respectively connected to the signal input end;

[0008] The output end of the filtering unit is connected to the second input end of the steady-state error acquisition unit and the first input end of the steady-state error correction unit respectively, and the output end of the steady-state error acquisition unit is connected to the second input end of the steady-state error correction unit;

[0009] The output end of the steady-state error correction unit is a signal output end;

[0010] The filtering unit is used to receive an input signal and obtain an output signal after filtering the input signal;

[0011] The steady-state error acquisition unit is used to acquire the input signal and the output signal of the filtering unit, and obtain a steady-state error signal according to the input signal and the output signal;

[0012] The steady-state error correction unit is used to linearly superimpose the steady-state error signal and the output signal of the filtering unit to obtain a correction signal.

[0013] Further, the steady-state error acquisition unit includes a first inertia filter, a second inertia filter and a first subtractor;

[0014] The input end of the first inertia filter is connected to the signal input end, and the output end of the first inertia filter is connected to the minuend end of the first subtractor;

[0015] The subtrahend terminal of the first subtractor is connected to the output terminal of the filtering unit;

[0016] The output end of the subtractor is connected to the input end of the second inertia filter, and the output end of the second inertia filter is connected to the second input end of the steady-state error correction unit.

[0017] Further, the steady-state error correction unit is an adder;

[0018] The first input end of the adder is connected to the output end of the filtering unit, the second input end of the adder is connected to the second output end of the steady-state error acquisition unit, and the output end of the adder is connected to the signal output end.

[0019] Furthermore, the filtering unit is a fastest tracking filter.

[0020] Furthermore, the first inertia filter and the second inertia filter are both first-order inertia filters.

[0021] In an embodiment of the present invention, a steady-state error acquisition unit is respectively connected to a signal input terminal and a signal output terminal of a filtering unit, so as to acquire an input signal and an output signal of the filtering unit, and obtain a steady-state error signal by superimposing the input signal and the output signal of the filtering unit; by outputting the steady-state error signal to a steady-state error correction unit, the steady-state error correction unit linearly superimposes the steady-state error signal and the filtering unit signal to obtain an output signal, which is a correction signal of the fastest tracking filter, and the correction signal offsets the steady-state error between the output signal and the input signal of the fastest tracking filter, thereby eliminating the steady-state error between the output signal and the input signal of the fastest filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a structural schematic diagram of a filtering device provided by an embodiment of the present invention;

[0023] Figure 2 is another structural schematic diagram of a filtering device provided by an embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of a fastest tracking filter provided by an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of steady-state error comparison of the filter provided by an embodiment of the present invention;

[0026] Figure 5 It is a schematic diagram of process output comparison of the filter provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0029] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0030] See also Figure 1 An embodiment of the present invention provides a filtering device, comprising:

[0031] A filtering unit 10, a steady-state error acquisition unit 20 and a steady-state error correction unit 30;

[0032] The input end of the filter unit 10 and the first input end of the steady-state error acquisition unit 20 are respectively connected to the signal input end;

[0033] The output end of the filtering unit 10 is connected to the second input end of the steady-state error acquisition unit 20 and the first input end of the steady-state error correction unit 30 respectively, and the output end of the steady-state error acquisition unit 20 is connected to the second input end of the steady-state error correction unit 30;

[0034] The output end of the steady-state error correction unit 30 is a signal output end;

[0035] The filter unit 10 is used to receive an input signal and obtain an output signal after filtering the input signal;

[0036] The steady-state error acquisition unit 20 is used to acquire the input signal and the output signal of the filter unit 10, and obtain a steady-state error signal according to the input signal and the output signal;

[0037] The steady-state error correction unit 30 is used to linearly superimpose the steady-state error signal with the output signal of the filtering unit 10 to obtain a correction signal.

[0038] In the embodiment of the present invention, the steady-state error acquisition unit 20 is respectively connected to the signal input end and the signal output end of the filtering unit 10, so as to acquire the input signal and the output signal of the filtering unit 10, and obtain the steady-state error signal by superimposing the input signal and the output signal of the filtering unit 10; by outputting the steady-state error signal to the steady-state error correction unit 30, the steady-state error correction unit 30 linearly superimposes the steady-state error signal with the signal of the filtering unit 10 to obtain an output signal, which is the correction signal of the fastest tracking filter, and the correction signal offsets the steady-state error between the output signal and the input signal of the fastest tracking filter, thereby eliminating the steady-state error between the output signal and the input signal of the fastest filter.

[0039] See also Figure 2 , the steady-state error acquisition unit 20 includes a first inertial filter 21, a second inertial filter 22 and a first subtractor 23;

[0040] The input end of the first inertia filter 21 is connected to the signal input end, and the output end of the first inertia filter 21 is connected to the minuend end of the first subtractor 23;

[0041] The subtrahend terminal of the first subtractor 23 is connected to the output terminal of the filter unit 10;

[0042] The output end of the subtractor 23 is connected to the input end of the second inertia filter 22 , and the output end of the second inertia filter 22 is connected to the second input end of the steady-state error correction unit.

[0043] In the embodiment of the present invention, two input ends of the first subtractor 23: the minuend end and the subtrahend end respectively receive the output signal of the first inertial filter 21 of the input signal of the filter unit 10 and the output signal of the filter unit 10, so that the preliminary steady-state error signal can be output at the output end of the first subtractor 23. The output end of the first subtractor 23 is connected to the output end of the second inertial filter 22, and the preliminary steady-state error signal is transmitted to the second inertial filter 22, and the final steady-state error signal is obtained through the second inertial filter 22.

[0044] Please continue reading Figure 2 , the steady-state error correction unit 30 is an adder 31;

[0045] A first input terminal of the adder 31 is connected to the output terminal of the filter unit 10 , a second input terminal of the adder 31 is connected to the second output terminal of the steady-state error acquisition unit 20 , and an output terminal of the adder 31 is connected to the signal output terminal.

[0046] In the embodiment of the present invention, the second inertial filter 22 transmits the final steady-state error signal to the steady-state error correction unit, i.e., the adder 31, through the signal output terminal. The steady-state error signal and the output signal of the fastest tracking filter are linearly superimposed by the adder 31 to obtain a correction signal, thereby effectively offsetting the steady-state error between the output signal of the fastest tracking filter and the input signal.

[0047] Please continue reading Figure 2 , the filtering unit 10 is a fastest tracking filter.

[0048] In the embodiment of the present invention, the structure of the fastest tracking filter is as follows: Figure 3 As shown, it includes a pure lag link, a subtractor 23 and an integration link.

[0049] In one embodiment, the first inertial filter 21 and the second inertial filter 22 are both first-order inertial filters.

[0050] In one embodiment, the transfer function expression of the fastest tracking filter FTF is:

[0051]

[0052] Among them, FTF is the abbreviation of the fastest tracking filter, FTF(s) is the transfer function of FTF, s is the Laplace operator, T FTF is the time constant of FTF, in seconds.

[0053] The transfer function expressions of the first inertial filter 21 and the second inertial filter 22 are respectively:

[0054]

[0055]

[0056] Wherein, FOIF_A is the first inertial filter 21, FOIF_B is the second inertial filter 22, FOIF_A(s) is the transfer function of FOIF_A, s is the Laplace operator, T FOIF_A is the time constant of FOIF_A, in seconds; FOIF_B(s) is the transfer function of FOIF_B, T FOIF_B is the time constant of FOIF_B, in seconds.

[0057] The transfer function of the filtering device provided in this embodiment is:

[0058] CFTF(s)=FTF(s)+[FOIF_A(s)-FTF(s)]FOIF_B(s)

[0059] Among them, CFTF is the English abbreviation of the filtering device, FTF(s) is the transfer function of FTF, CFTF(s) is the transfer function of CFTF, s is the Laplace operator, FOIF_A(s) is the transfer function of FOIF_A, and FOIF_B(s) is the transfer function of FOIF_B.

[0060] See also Figure 4 , set the process output PV of FTF FTF (t), relative to the theoretical FTF (TFTF) process output PV TFTF The steady-state error of (t) is -1%. It can be understood that TFTF is FTF without steady-state error, and the process output of CFTF is PV CFTF (t); Set T FTF =100s, T FOIF_A =333s, T FOIF_B = 2000s, input unit step, get PV FTF (t)-PV TFTF (t), PV CFTF (t)-PV TFTF (t) Experimental results.

[0061] Please continue reading Figure 4 , FTF process output PV FTF (t) After entering the steady state, the error relative to TFTF is -1%; the process output PV of CFTF CFTF (t) is smaller than the error of TFTF, and as t increases, the error approaches 0. That is, the filtering device CFTF provided by the embodiment of the present invention can eliminate the problem of steady-state error existing in the fastest tracking filter FTF.

[0062] In one embodiment, based on the parameters of the above embodiments, the output characteristics of the filtering device CFTF and the first-order inertial filter FOIF are compared.

[0063] The transfer function of the first-order inertial filter FOIF is:

[0064]

[0065] Where FOIF(s) is the transfer function of FOIF, T FOIF is the inertia time constant of FOIF, in s.

[0066] See also Figure 5 , input unit step signal at the input of CFTF and FOIF, where T FOIF =T FTF = 100s, get the CFTF process output PV CFTF (t), FOIF process output PV FOIF (t) comparison results.

[0067] Please continue reading Figure 5 , the process output PV of the first-order inertial filter FOIF FOIF (t) obviously lags behind the process output PV of the filter device CFTF of the embodiment of the present invention. CFTF (t).

[0068] The filtering device CFTF provided in the embodiment of the present invention can effectively offset the steady-state error of the fastest tracking filter FTF, and can be applied to: process signal denoising filtering, such as filtering of the main steam temperature process signal and the main steam pressure process signal of a thermal power unit; constructing a fastest integrator (FI), a fastest proportional-integral controller (FPI), a fastest controller (AFC), etc.

[0069] The above are preferred embodiments of the present invention. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A filtering device, characterized in that: include: A filtering unit, a steady-state error acquisition unit and a steady-state error correction unit; The input end of the filtering unit and the first input end of the steady-state error acquisition unit are respectively connected to the signal input end; The output end of the filtering unit is connected to the second input end of the steady-state error acquisition unit and the first input end of the steady-state error correction unit respectively, and the output end of the steady-state error acquisition unit is connected to the second input end of the steady-state error correction unit; The output end of the steady-state error correction unit is a signal output end; The filtering unit is used to receive an input signal and obtain an output signal after filtering the input signal; The steady-state error acquisition unit is used to acquire the input signal and the output signal of the filtering unit, and obtain a steady-state error signal according to the input signal and the output signal; The steady-state error correction unit is used to linearly superimpose the steady-state error signal and the output signal of the filtering unit to obtain a correction signal.

2. The filtering device according to claim 1, characterized in that The steady-state error acquisition unit includes a first inertia filter, a second inertia filter and a first subtractor; The input end of the first inertia filter is connected to the signal input end, and the output end of the first inertia filter is connected to the minuend end of the first subtractor; The subtrahend terminal of the first subtractor is connected to the output terminal of the filtering unit; The output end of the first subtractor is connected to the input end of the second inertia filter, and the output end of the second inertia filter is connected to the second input end of the steady-state error correction unit.

3. The filtering device according to claim 1, characterized in that The steady-state error correction unit is an adder; The first input end of the adder is connected to the output end of the filtering unit, the second input end of the adder is connected to the output end of the steady-state error acquisition unit, and the output end of the adder is connected to the signal output end.

4. The filtering device according to claim 1, characterized in that The filtering unit is a fastest tracking filter.

5. The filtering device according to claim 2, characterized in that The first inertia filter and the second inertia filter are both first-order inertia filters.

Images