CN116449739B - Photovoltaic inverter and Taylor series-based sampling signal hysteresis compensation method thereof - Google Patents
Photovoltaic inverter and Taylor series-based sampling signal hysteresis compensation method thereof Download PDFInfo
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Abstract
The invention provides a Taylor series-based sampling signal hysteresis compensation method for a photovoltaic inverter, which comprises the following steps of: a signal sampling unit for periodically acquiring a sampling signal; and the micro control unit performs hysteresis compensation on the current sampling signal acquired by the signal sampling unit based on the Taylor median theorem to obtain a corresponding actual signal, thereby compensating the influence of the delay of the sampling signal on the system and improving the stability of closed-loop control of the system.
Description
[ Field of technology ]
The invention belongs to the technical field of signals, and particularly relates to a photovoltaic inverter and a Taylor series-based sampling signal hysteresis compensation method thereof.
[ Background Art ]
The voltage and current signal sampling circuit of the photovoltaic inverter generally needs RC resistance-capacitance filtering to filter high-frequency interference signals, but delay of sampling signals is brought to the RC resistance-capacitance filtering, so that the signal value of AD sampling lags behind an actual value, a delay link is introduced in a control feedback loop of the photovoltaic inverter, and stability margin and robustness of a control system are reduced.
Accordingly, there is a need to provide an improved solution to overcome the above-mentioned problems.
[ Invention ]
The technical problem to be solved by the invention is to provide a photovoltaic inverter and a sampling signal hysteresis compensation method based on Taylor series, which can compensate the influence of time delay of a sampling signal on a system, thereby improving the stability of closed-loop control of the system.
In order to solve the above-mentioned problems, according to a first aspect of the present invention, there is provided a sampling signal lag compensation method based on taylor series, comprising: a signal sampling unit for periodically acquiring a sampling signal; and the micro control unit is used for performing hysteresis compensation on the current sampling signal acquired by the signal sampling unit based on the Taylor median theorem so as to acquire a corresponding actual signal.
Further, hysteresis compensation is performed on the current sampling signal acquired by the signal sampling unit based on the equation 1 obtained by the taylor median theorem,
The formula 1 obtained by the taylor median theorem is:
Wherein x 0 is the current sampling time f (x 0), the current sampling signal, and f (x 0+td) is the actual signal corresponding to the current sampling signal; f (x -1),f(x-2),f(x-3) is the sampling signals of the signal sampling unit recorded by the micro-etching control unit at 1,2 and 3 sampling moments before the current sampling moment x 0 respectively;
T d＝k*Ts,td is the delay of the sampling signal, T s is the sampling period of the sampling signal obtained by the signal sampling unit, and k is the coefficient.
Further, the signal sampling unit is an analog-to-digital converter; the signal sampling unit is a voltage or current signal sampling circuit.
Further, the k value in the formula 1 is calculated according to the parameters of the hardware circuit of the signal sampling unit.
Further, the derivation process of equation 1 from the taylor median theorem is:
from the Taylor median theorem, if the function f (x) has a derivative of (n+1) th order over a certain open interval (a, b) of x 0, then for any x ε (a, b), there is
Wherein the method comprises the steps ofIs a Taylor polynomial of degree n, which has an error with f (x)Called the taylor form of order n; assuming that the delay of the sampled signal is t d, let the sampled signal be f (x n), where x n is the sampling sequence x n∈[0,1,2...n]*Ts,Ts is the sampling period of the signal, the actual signal at sampling time x n is denoted as f (x n+td) due to the existence of hardware delay, and it is obtained by expanding at x n according to the taylor series: equation 1:
Wherein, since t d is small, taylor type 4 Having trended towards 0, in order to reduce the computational effort of the micro control unit, it is possible to:
Equation 2:
Assuming that the current signal sampled by the signal sampling unit is f (x 0),f(x-n) which is the sampled signal of the signal sampling unit n sampling periods before the current sampling time x 0, the actual signal corresponding to the current sampled signal is: Since the sampling period T s is small, the discretization uses the linear calculation of adjacent sampling points to replace derivative calculation, so that T d＝k*Ts
The equation 1 thus derived for predicting the actual signal corresponding to the current sampled signal is:
According to another aspect of the present invention, there is provided a photovoltaic inverter including a taylor series-based sampling signal hysteresis compensation method including: a signal sampling unit for periodically acquiring a sampling signal; and the micro control unit is used for performing hysteresis compensation on the current sampling signal acquired by the signal sampling unit based on the Taylor median theorem so as to acquire a corresponding actual signal.
Further, the signal sampling unit in the taylor series-based sampling signal hysteresis compensation method is a voltage or current signal sampling circuit of the photovoltaic inverter.
Compared with the prior art, the method and the device for compensating the delay of the signal sampling unit have the advantages that the delay compensation is carried out on the current sampling signal acquired by the signal sampling unit based on the Taylor median theorem so as to obtain the corresponding actual signal, so that the influence of the delay of the sampling signal on the system is compensated, and the stability of closed loop control of the system can be improved without adding an additional hardware circuit.
Other objects, features and advantages of the present invention will be described in the following detailed description of the embodiments with reference to the accompanying drawings.
[ Description of the drawings ]
The invention will be more readily understood by reference to the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:
FIG. 1 is a block diagram of a sampled signal lag compensation circuit based on a Taylor series in one embodiment of the invention;
FIG. 2 is a bird diagram of an inverter control system without hysteresis compensation of a sampled signal in one embodiment;
FIG. 3 is a bird diagram of an inverter control system employing the present invention for hysteresis compensation of a sampled signal in one embodiment.
[ Detailed description ] of the invention
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. The terms "plurality" and "a plurality" as used herein mean two or more. "and/or" in the present invention means "and" or ".
Referring to fig. 1, a block diagram of a taylor series based sampling signal hysteresis compensation circuit according to an embodiment of the present invention is shown. The taylor series based sampled signal lag compensation method shown in fig. 1 includes a signal sampling unit 110 and a micro control unit 120.
The signal sampling unit 110 is used for periodically acquiring a sampling signal. In one embodiment, the signal sampling unit 110 is an analog-to-digital converter; the signal sampling unit 110 is a voltage or current signal sampling circuit.
The micro control unit 120 performs hysteresis compensation on the current sampling signal acquired by the signal sampling unit 110 based on the taylor median theorem to obtain a corresponding actual signal, thereby compensating the influence of the delay of the sampling signal on the system, and improving the stability of closed loop control of the system without adding an additional hardware circuit.
In one embodiment, the micro control unit 120 performs hysteresis compensation on the current sampling signal acquired by the signal sampling unit 110 based on equation 1 obtained by taylor's median theorem to obtain a corresponding actual signal.
The derivation of equation 1 from the taylor median theorem is specifically described below.
From the Taylor median theorem, if the function f (x) has a derivative of (n+1) th order over a certain open interval (a, b) of x 0, then for any x ε (a, b), there is
Wherein the method comprises the steps ofIs a Taylor polynomial of degree n, which has an error with f (x)Called the taylor form of order n; let the sampling signal be f (x n) assuming a delay of the sampling signal (or delay of the sampling system) of t d, where x n is the sampling sequence
X n∈[0,1,2...n]*Ts,Ts is the sampling period of the signal, and the actual signal at sampling instant x n is denoted as f (x n+td) due to the existence of hardware delay, and is obtained by expanding at x n according to the taylor series:
Equation 1:
Wherein, since t d is small, taylor type 4 Having trended towards 0, in order to reduce the computational effort of the MCU (Microcontroller Unit, i.e. the micro-control unit) 120, it is possible to obtain:
Equation 2:
Assuming that the current signal sampled by the signal sampling unit 110 is f (x 0),f(x-n) which is the sampled signal of the signal sampling unit 110 n sampling periods before the current sampling time x 0, the prediction compensated signal (i.e., the actual signal corresponding to the current sampled signal) is:
Because the sampling period (or sampling time) T s is very small, the discretization can use the linear calculation of adjacent sampling points to replace derivative calculation, can prevent the differential link from amplifying interference signals in high frequency band, and make T d＝k*Ts
Equation 1 for predicting an actual signal corresponding to a current sampling signal (or equation 1 for performing hysteresis compensation on the current sampling signal acquired by the signal sampling unit 110 to obtain a corresponding actual signal) may be obtained as follows:
Wherein x 0 is the current sampling time f (x 0), the current sampling signal, and f (x 0+td) is the actual signal corresponding to the current sampling signal; f (x -1),f(x-2),f(x-3) is the sampling signal of the signal sampling unit 110 recorded by the micro control unit 120 at 1,2,3 sampling times before the current sampling time x 0, respectively; t d＝k*Ts,td is the delay of the sampling signal, T s is the sampling period of the sampling signal obtained by the signal sampling unit 110, and k is the coefficient.
Since the delay t d of the sampling signal of the signal sampling unit 110 is determined by the parameters of the hardware circuit, the k value in equation 1 can be calculated according to the parameters of the hardware circuit, and the actual signal corresponding to the current sampling signal is predicted by equation 1 (or the current sampling signal obtained by the signal sampling unit is subjected to hysteresis compensation by equation 1 to obtain the corresponding actual signal). The prediction-compensated actual signal is used to control the system instead of the sampling signal of the signal sampling unit 110, so that the robustness and stability margin of the system can be increased.
Assume that the sampling delay brought by hardware is 1 sampling period, i.e., k=1; the predicted and compensated signal (i.e., the actual signal corresponding to the current sampled signal) is further obtained as:
Wherein f (x -1),f(x-2),f(x-3) is the sampling signal of the signal sampling unit 110 recorded by the micro control unit 120 at 1,2,3 sampling times before the current sampling time x 0, respectively; next, the predicted and compensated signal (i.e., the actual signal corresponding to the current sampled signal) is used to replace the sampled signal of the signal sampling unit 110 in the feedback link of the designed closed-loop control system, so as to improve the stability margin of the system.
According to another aspect of the invention, a photovoltaic inverter is provided that includes a taylor series based sampling signal lag compensation method as described above. The signal sampling unit 110 in the taylor series-based sampling signal hysteresis compensation method is a voltage or current signal sampling circuit of the photovoltaic inverter.
FIG. 2 is a B-chart of an inverter control system without hysteresis compensation for a sampled signal in one embodiment; referring now to fig. 3, therein is shown a bode diagram of an inverter control system employing the present invention for hysteresis compensation of a sampled signal in one embodiment. Comparing fig. 2 and fig. 3, it can be known that the present invention performs hysteresis compensation on the current sampling signal obtained by the signal sampling unit 110 based on the taylor median theorem to obtain a corresponding actual signal, so as to compensate the influence of the delay of the sampling signal on the system, and improve the stability of closed loop control of the system without adding additional hardware circuits.
In summary, the technical effects or advantages of the present invention are as follows:
1. and when the hardware samples and keeps a certain bandwidth to filter noise signals, the influence of sampling delay on the stability of the system is reduced, and the overall stability of the control system is improved.
2. The hardware cost of the equipment is not increased, and the economic benefit is improved.
In this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a list of elements is included, and may include other elements not expressly listed.
In this document, terms such as front, rear, upper, lower, etc. are defined with respect to the positions of the components in the drawings and with respect to each other, for clarity and convenience in expressing the technical solution. It should be understood that the use of such orientation terms should not limit the scope of the claimed application.
The embodiments described above and features of the embodiments herein may be combined with each other without conflict.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (5)
1. A method for taylor series based sample signal lag compensation, comprising:
a signal sampling unit for periodically acquiring a sampling signal;
the micro control unit is used for performing hysteresis compensation on the current sampling signal acquired by the signal sampling unit based on the Taylor median theorem so as to acquire a corresponding actual signal;
Hysteresis compensation is performed on the current sampling signal acquired by the signal sampling unit based on equation 1 obtained by taylor median theorem,
The formula 1 obtained by the taylor median theorem is:
Wherein x 0 is the current sampling time, f (x 0) is the current sampling signal, and f (x 0+td) is the actual signal corresponding to the current sampling signal; f (x -1),f(x-2),f(x-3) is the sampling signals of the signal sampling unit recorded by the micro control unit at 1,2 and 3 sampling moments before the current sampling moment x 0 respectively; t d＝k*Ts,td is the delay of the sampling signal, T s is the sampling period of the sampling signal obtained by the signal sampling unit, and k is the coefficient.
2. The method of claim 1, wherein,
The signal sampling unit is an analog-to-digital converter;
The signal sampling unit is a voltage or current signal sampling circuit.
3. The method of claim 1, wherein,
And calculating the k value in the formula 1 according to the parameters of the hardware circuit of the signal sampling unit.
4. The method of claim 1, wherein,
The derivation of equation 1 from the taylor median theorem is:
From the Taylor median theorem, if the function f (x) has a derivative of (n+1) th order over a certain open interval (a, b) of x 0, then for any x ε (a, b), there is
Wherein the method comprises the steps ofIs a Taylor polynomial of degree n, which has an error with f (x)Called the taylor form of order n;
Assuming that the delay of the sampled signal is t d, let the sampled signal be f (x n), where x n is the sampling sequence x n∈[0,1,2…n]*Ts,Ts is the sampling period of the signal, the actual signal at sampling time x n is denoted as f (x n+td) due to the existence of hardware delay, and it is obtained by expanding at x n according to the taylor series:
Equation 1:
Wherein, since t d is small, taylor type 4 Having trended towards 0, in order to reduce the computational effort of the micro control unit, it is possible to:
Equation 2:
Assuming that the current signal sampled by the signal sampling unit is f (x 0),f(x-n) which is the sampled signal of the signal sampling unit n sampling periods before the current sampling time x 0, the actual signal corresponding to the current sampled signal is:
Since the sampling period T s is small, the discretization uses the linear calculation of adjacent sampling points to replace derivative calculation, so that T d＝k*Ts
The equation 1 thus derived for predicting the actual signal corresponding to the current sampled signal is:
5. a photovoltaic inverter is characterized in that,
Comprising a taylor series based sampled signal lag compensation method as claimed in any one of claims 1-4.
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