CN113804949A - Amplitude determination method and device suitable for wide-frequency-conversion alternating-current power generation system - Google Patents
Amplitude determination method and device suitable for wide-frequency-conversion alternating-current power generation system Download PDFInfo
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Abstract
The application belongs to the field of alternating current power supply application, and particularly relates to an amplitude determination method and device suitable for a wide-frequency-conversion alternating current power generation system. The method comprises the following steps: step S1, for the input AC signal source R (S), pass through the first transfer function G1(s) obtaining a first output signal R1(s); step S2, multiplying the first output signal by a scaling factor K, and then passing through a second transfer function G2(s) obtaining a second output signal y(s); step S3, performing inverse Laplace transform on the second output signal Y (S) to obtain the amplitude of the input signal; and step S4, executing corresponding over-frequency protection or under-frequency protection according to the amplitude of the input signal. The method and the device can realize the quick tracking of the effective value of the sinusoidal signal and improve the robustness of the system.
Description
Technical Field
The application belongs to the field of alternating current power supply application, and particularly relates to an amplitude determination method and device suitable for a wide-frequency-conversion alternating current power generation system.
Background
The control performance of the system is directly influenced by the fact that the effective value of the three-phase alternating voltage is obtained as the feedback quantity of the voltage regulation control system. In addition, in order to improve the quality of the electric energy output by the power generation system and the reliability of the system, the voltage of a voltage regulation point of the power generation system needs to be detected in real time and corresponding overvoltage and undervoltage protection needs to be executed. How to efficiently and accurately obtain an effective value of an alternating current power supply, the current main method comprises the following steps:
instantaneous value method:
Obviously, the above equation is only true under three-phase symmetric loads. The unbalanced three-phase signal cannot be processed, and the harmonic component of the input signal cannot be filtered.
Integration method:
from the root mean square over a period, one can derive:
since the existence of integration inevitably causes signal delay, and the period of the signal must be known, additional frequency measurement work needs to be added.
Half-cycle integration method:
considering the periodicity and symmetry of the voltage waveform, there are:
although the response speed is improved compared with the integral method, the problems of accumulation and periodic acquisition are not avoided, which is more prominent in the case of a frequency conversion system.
Disclosure of Invention
In order to solve the technical problem, the application provides an amplitude determination method and an amplitude determination device suitable for a wide-frequency-conversion alternating-current power generation system, and provides a method for rapidly determining the amplitude of a signal according to the principle that any signal can be synthesized by an orthogonal function set.
The application provides in a first aspect an amplitude determination method suitable for a wide-frequency-conversion alternating-current power generation system, which mainly includes:
step S1, for the input AC signal source R (S), pass through the first transfer function G1(s) obtaining a first output signal R1(s)；
Step S2, multiplying the first output signal by a scaling factor K, and then passing through a second transfer function G2(s) obtaining a second output signal y(s);
step S3, inverse Laplace transform is carried out on the second output signal Y (S) to obtain the effective value of the input signal;
step S4, executing corresponding over-frequency or under-frequency protection according to the effective value of the input signal;
wherein,
parameter omeganZeta is the system damping for undamped natural oscillation frequency,
preferably, before step S1, the method further includes:
obtaining an AC input signal r (t) and taking its absolute value r1(t)；
For AC input signal r1(t) performing a Ralsberg transform to obtain an AC signal source R(s).
Preferably, the first transfer function G1In(s), undamped natural oscillation frequency omegan300 pi and a system damping zeta of 1.1.
Preferably, the second transfer function G2In(s), undamped natural oscillation frequency omegan300 pi and system damping zeta 0.707.
The present application provides in a second aspect an amplitude determination apparatus for a wide-frequency-conversion ac power generation system, which mainly includes:
a first transmission module for the first transmission module,for input AC signal source R(s) via a first transfer function G1(s) obtaining a first output signal R1(s)；
A second transfer module for multiplying the first output signal by a scaling factor K and then passing through a second transfer function G2(s) obtaining a second output signal y(s);
the output conversion module is used for carrying out inverse Laplace conversion on the second output signal Y(s) to obtain an effective value of the input signal;
the frequency protection module is used for executing corresponding over-frequency protection or under-frequency protection according to the effective value of the input signal;
wherein,
parameter omeganZeta is the system damping for undamped natural oscillation frequency,
preferably, the apparatus further comprises:
an AC input signal acquisition unit for acquiring AC input signal r (t) and taking its absolute value r1(t)；
A Laplace transform unit for applying to the AC input signal r1(t) performing a Ralsberg transform to obtain an AC signal source R(s).
Preferably, the first transfer function G1In(s), undamped natural oscillation frequency omegan300 pi and a system damping zeta of 1.1.
Preferably, the second transfer function G2In(s), undamped natural oscillation frequency omegan300 pi and system damping zeta 0.707.
According to the method, the design ideas of Fourier transform and a filter are utilized, the quick tracking of the effective value of the sinusoidal signal is realized by utilizing instantaneous data, and the filtering characteristic of the algorithm obviously improves the robustness of the system.
Drawings
Fig. 1 is a flow chart of an amplitude determination method applicable to a wide-frequency-conversion ac power generation system according to the present application.
Fig. 2 is a schematic diagram of an input signal.
FIG. 3 is an output signal diagram for the condition of the input signal of FIG. 2.
FIG. 4 is a graph of the two output signals for the condition of the input signals of FIG. 2.
FIG. 5 is a three output signal diagram for the operating condition of the input signal of FIG. 2.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all embodiments of the present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application, and should not be construed as limiting the present application. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application. Embodiments of the present application will be described in detail below with reference to the drawings.
In a first aspect, the present application provides an amplitude determination method suitable for a wide-frequency-conversion ac power generation system, which is a method for rapidly calculating an amplitude of a power supply, and as shown in fig. 1, the method mainly includes:
step S1, for the input AC signal source R (S), pass through the first transfer function G1(s) obtaining a first output signal R1(s)；
Step S2, multiplying the first output signal by a scaling factor K, and then passing through a second transfer function G2(s) obtaining a second output signal y(s);
step S3, inverse Laplace transform is carried out on the second output signal Y (S) to obtain the effective value of the input signal;
step S4, executing corresponding over-frequency or under-frequency protection according to the effective value of the input signal;
wherein,
parameter omeganZeta is the system damping for undamped natural oscillation frequency,
the principles of the present application are explained herein.
According to the physical meaning of the orthogonal set (the orthogonal function set can synthesize any signal), therefore:
therefore, the signal is filtered to obtain the information a independent of frequency0. It can be shown that0Is a variable related to the amplitude of the input signal.
For periodic function f (x) (period 2 π):
thus:
when f (x) ═ asin (x) |:
thus, the amplitude of the input signal can be obtained.
In some optional embodiments, before step S1, the method further includes:
obtaining an AC input signal r (t) and taking its absolute valuer1(t)；
For AC input signal r1(t) performing a Ralsberg transform to obtain an AC signal source R(s).
The method obtains the absolute value of an input alternating current signal source r (t) to obtain a signal r1(t), namely:
r1(t)＝|r(t)|
will r is1(t) signal as G1(s) input and output signals r2(t) that is
In the formula, R1(s) and R2(s) respectively represent the input signals r1(t) and the output signal r2(t) Rad change, G1(s) is a second order Butterworth low-pass filter (G)1(s) other transfer function forms with low pass filtering properties may be selected).
Will r is2(t) multiplying the signal by a scaling factor K as G2(s) input and output signals y (t), i.e
In the formula, R2(s) and Y(s) represent the input signal r, respectively2(t) and the Law change of the output signal y (t), G2(s) is a second order Butterworth low-pass filter (G)2(s) other transfer function forms with low pass filtering properties may be selected).
G1The object of the filtering of(s) is the absolute value of the sinusoidal signal, corresponding to a strongly pulsating direct current signal; g2The object of the filtering of(s) is a relatively smooth sinusoidal effective value signal. Therefore, the proper filtering form and filtering parameters can be selected according to different filtering objects.
The effective value of the input alternating current signal is set to be 115V, the frequency is 583Hz, and the following steps are carried out:
the system response rapidity and the steady-state index are contradictory, and the system damping and the cut-off frequency can be adjusted according to actual requirements to carry out compromise processing. Thus, in some alternative embodiments, the first transfer function G1In(s), undamped natural oscillation frequency omegan300 pi and a system damping zeta of 1.1. In some alternative embodiments, the second transfer function G2In(s), undamped natural oscillation frequency omegan300 pi and system damping zeta 0.707. Accordingly, the two filters are:
in order to fully illustrate the robustness and effectiveness of the algorithm, the output of the algorithm under the following working conditions is tested, the three working conditions are respectively shown in fig. 3-5, an input signal is shown in fig. 2, a relatively smooth line is a distorted curve, another line is an undistorted curve, a line positioned on the upper side in fig. 3 is a distorted curve, a line positioned on the lower side is an undistorted curve, and it can be seen that under the condition that the input signal is distorted, the deviation of the calculation result of the algorithm is only 0.17%; the output can also track quickly in the case of sudden changes (frequency or amplitude) in the input signal.
The working condition I is as follows: distorted input signals (phase A adds 10 negative sequence harmonics with amplitude variation of 0.1 pu; phase B adds 1 negative sequence harmonics);
working conditions are as follows: when the time is 0.2s, the frequency of the input signal is suddenly changed by 167 Hz;
working conditions are as follows: at 0.2s, the input signal amplitude abruptly changes by 0.1 pu.
The application provides a calculation algorithm suitable for the power supply amplitude of a wide-frequency-conversion alternating-current power generation system, and the algorithm utilizes the design ideas of Fourier transform and a filter and utilizes instantaneous data to realize the rapid tracking of the effective value of a sinusoidal signal. The algorithm is implemented on a DSP28335 processor platform and only 800ns is needed, and if secondary filtering is omitted (certain precision is sacrificed), only 450ns can obtain the effective value of the input signal. In addition, the filtering characteristic of the algorithm obviously improves the system robustness, and the test results are shown in FIGS. 3-5.
The second aspect of the present application provides an amplitude determining apparatus suitable for a wide-frequency-conversion ac power generation system corresponding to the above method, which mainly includes:
a first transfer module for transferring the input AC signal source R(s) through a first transfer function G1(s) obtaining a first output signal R1(s)；
A second transfer module for multiplying the first output signal by a scaling factor K and then passing through a second transfer function G2(s) obtaining a second output signal y(s);
the output conversion module is used for carrying out inverse Laplace conversion on the second output signal Y(s) to obtain an effective value of the input signal;
the frequency protection module is used for executing corresponding over-frequency protection or under-frequency protection according to the effective value of the input signal;
wherein,
parameter omeganZeta is the system damping for undamped natural oscillation frequency,
in some optional embodiments, the apparatus further comprises:
an AC input signal acquisition unit for acquiring AC input signal r (t) and taking its absolute value r1(t)；
A Laplace transform unit for applying to the AC input signal r1(t) performing a Ralsberg transform to obtain an AC signal source R(s).
In some alternative embodiments, the first transfer function G1In(s), undamped natural oscillation frequency omegan300 pi and a system damping zeta of 1.1.
In some alternative embodiments, the second transfer function G2In(s), natural vibration without dampingOscillation frequency omegan300 pi and system damping zeta 0.707.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (8)
1. An amplitude determination method suitable for a wide-frequency-conversion alternating-current power generation system is characterized by comprising the following steps:
step S1, for the input AC signal source R (S), pass through the first transfer function G1(s) obtaining a first output signal R1(s)；
Step S2, multiplying the first output signal by a scaling factor K, and then passing through a second transfer function G2(s) obtaining a second output signal y(s);
step S3, inverse Laplace transform is carried out on the second output signal Y (S) to obtain the effective value of the input signal;
step S4, executing corresponding over-frequency or under-frequency protection according to the effective value of the input signal;
wherein,
parameter omeganZeta is the system damping for undamped natural oscillation frequency,
2. the amplitude determination method for the wide-frequency ac power generation system according to claim 1, wherein before step S1, the method further comprises:
obtaining an AC input signal r (t) and taking its absolute value r1(t)；
For AC input signal r1(t) performing a Ralsberg transform to obtainObtaining an AC signal source R(s).
3. The amplitude determination method for a wide frequency conversion ac power generation system according to claim 1, wherein the first transfer function G1In(s), undamped natural oscillation frequency omegan300 pi and a system damping zeta of 1.1.
4. The amplitude determination method for a wide frequency conversion ac power generation system of claim 1, wherein the second transfer function G2In(s), undamped natural oscillation frequency omegan300 pi and system damping zeta 0.707.
5. An amplitude determination apparatus adapted for use in a wide-frequency ac power generation system, comprising:
a first transfer module for transferring the input AC signal source R(s) through a first transfer function G1(s) obtaining a first output signal R1(s)；
A second transfer module for multiplying the first output signal by a scaling factor K and then passing through a second transfer function G2(s) obtaining a second output signal y(s);
the output conversion module is used for carrying out inverse Laplace conversion on the second output signal Y(s) to obtain an effective value of the input signal;
the frequency protection module is used for executing corresponding over-frequency protection or under-frequency protection according to the effective value of the input signal;
wherein,
parameter omeganZeta is the system damping for undamped natural oscillation frequency,
6. the amplitude determination apparatus for a wide frequency conversion ac power generation system according to claim 5, further comprising:
an AC input signal acquisition unit for acquiring AC input signal r (t) and taking its absolute value r1(t)；
A Laplace transform unit for applying to the AC input signal r1(t) performing a Ralsberg transform to obtain an AC signal source R(s).
7. The amplitude-determining apparatus for a wide-conversion AC power generation system of claim 5, wherein the first transfer function G1In(s), undamped natural oscillation frequency omegan300 pi and a system damping zeta of 1.1.
8. The amplitude-determining apparatus for a wide-conversion AC power generation system of claim 5, wherein the second transfer function G2In(s), undamped natural oscillation frequency omegan300 pi and system damping zeta 0.707.
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