Voltage stabilizer voltage control method and system based on adaptive filter

Abstract

The invention relates to a voltage stabilizer voltage control method and system based on an adaptive filter. The method comprises the following steps that filter parameters are initialized, and an expected signal is set; obtaining a direct-current voltage of the transmission line, and obtaining an output signal of the filter according to the weight vector of the filter and the direct-current voltage; an error signal is obtained according to the output signal of the filter and the expected signal, and then the output voltage of the voltage stabilizer is adjusted; if the error signal meets the precision requirement, the current output signal is transmitted to an inverter to adjust the output voltage of the voltage stabilizer; if the error signal does not meet the precision requirement, dynamically adjusting a step factor in combination with an NLMS algorithm and a dynamic step factor method, updating a weight vector of the filter in real time according to the dynamically adjusted step factor and the error signal so as to adjust an output signal of the filter, and when the error signal meets the precision requirement, outputting the output signal of the filter. And adjusting the output voltage of the voltage stabilizer according to the output signal. Compared with the prior art, stable high-quality voltage output is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current power transmission, and in particular to a voltage control method and system for a voltage regulator based on an adaptive filter. Background Art

[0002] Flexible DC transmission technology is widely used in long-distance power transmission and voltage stabilization in specific scenarios, but it still faces many challenges in low-voltage stabilization systems. The ±375V DC transmission line between the source-side rectifier module and the user-side inverter module of the current system is susceptible to interference from high-frequency noise and harmonics, mainly due to the switching operation of power electronic devices and external electromagnetic environment interference. Due to the accumulation of noise and harmonic signals during the transmission process, the quality of the DC voltage input to the inverter module is significantly reduced, thereby affecting the reliability and normal operation of the user-side equipment. In addition, in order to reduce noise interference, the existing technology usually configures fixed-parameter LC passive filters on the source side and the user side. However, the noise frequency in the power system changes dynamically with the load and operating environment, and fixed-parameter filters are difficult to effectively deal with noise with uncertain frequencies, resulting in a significant decrease in filtering effect.

[0003] In addition, most of the existing low-voltage regulator control strategies are based on proportional integral (PI) or proportional integral differential (PID) methods. These traditional control methods are difficult to effectively distinguish between the fundamental and noise components in the signal when dealing with high-frequency noise and harmonic interference, which may lead to unstable output voltage regulation. Under complex working conditions and frequently changing load conditions, the existing PI / PID controllers often have problems of over- or under-regulation, resulting in distortion of the voltage waveform on the user side, which ultimately affects the operating status of the terminal equipment. In the existing technology, in the flexible DC system, the DC transmission line between the rectifier module and the inverter module has significant problems of noise and harmonic accumulation. The limitations of traditional filters and control strategies make it difficult for the regulator to stably output high-quality voltage. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a voltage control method and system for a voltage regulator based on an adaptive filter, so as to achieve the output of stable and high-quality voltage.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A voltage control method for a voltage regulator based on an adaptive filter, wherein the voltage regulator includes an inverter and a filter, and comprises the following steps: Initialize filter parameters and set expected signal; Acquire a DC voltage of the transmission line, and obtain an output signal of the filter according to a weight vector of the filter and the DC voltage; An error signal is obtained according to the output signal of the filter and the expected signal, and the output voltage of the voltage regulator is adjusted according to the error signal: If the error signal meets the accuracy requirement, the current filter output signal is transmitted to the inverter, and the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the voltage regulator; If the error signal does not meet the accuracy requirement, the step factor is dynamically adjusted according to the input signal and the error signal of the filter, and the weight vector of the filter is updated in real time according to the dynamically adjusted step factor and the error signal, thereby adjusting the output signal of the filter. When the error signal meets the accuracy requirement, the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the regulator.

[0006] Furthermore, the filter parameters include filter order, weight vector and step factor.

[0007] Furthermore, the filter order matches the filtering effect of the filter.

[0008] Furthermore, the step size factor matches the updating speed of the weight vector.

[0009] Furthermore, the output signal of the filter is: , In the formula, is the output signal of the filter, For the n The discretized DC voltage input signal at time instant, is the weight vector of the filter.

[0010] Furthermore, the error signal is: , In the formula, is the error signal, is the output signal of the filter, is the expected signal.

[0011] Furthermore, the input signal of the filter includes harmonics and high-frequency noise.

[0012] Furthermore, the dynamic adjustment formula of the step factor obtained by combining the NLMS algorithm and the dynamic step factor method is: , In the formula, is a constant, with a value of between; is a positive number that prevents the denominator from being zero; represents the energy of the input signal vector, is the error signal, is the maximum value of the error.

[0013] Furthermore, the updating formula of the weight vector is: , In the formula, is the step size factor, is the error signal, is the input signal vector.

[0014] According to another aspect of the present invention, there is provided a voltage control system for a voltage regulator based on an adaptive filter, comprising: Initialization module, used to initialize filter parameters and set expected signals; An output signal acquisition module, used to acquire a DC voltage, and obtain an output signal of the filter according to a weight vector of the filter and the DC voltage; A voltage regulating module, used to obtain an error signal according to the output signal of the filter and the expected signal, and to adjust the output voltage of the regulator according to the error signal: If the error signal meets the accuracy requirement, the current filter output signal is transmitted to the inverter, and the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the voltage regulator; If the error signal does not meet the accuracy requirement, the step factor is dynamically adjusted according to the input signal and the error signal of the filter, and the weight vector of the filter is updated in real time according to the dynamically adjusted step factor and the error signal, thereby adjusting the output signal of the filter. When the error signal meets the accuracy requirement, the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the regulator.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention dynamically adjusts the step factor according to the energy of the input signal and the size of the error signal, and uses the updated step factor to update the weight vector in real time to ensure that the output of the filter gradually approaches the expected signal, thereby suppressing noise and harmonics. With the dynamic adjustment of the weight, the adaptive filter continuously optimizes the output signal quality, making the voltage waveform more stable and pure. By dynamically adjusting the step size and weight, the adaptability of the filter is significantly improved, and it can efficiently cope with multi-frequency noise changes, effectively improving the quality of the voltage output.

[0016] 2. The present invention uses an adaptive filter to automatically adjust the filter parameters according to the voltage signal collected in real time, dynamically adapt to the changes of noise and harmonics of different frequencies, improve the suppression effect of high-frequency noise and harmonics, and effectively prevent voltage fluctuations caused by harmonic accumulation, thereby ensuring that the inverter module obtains a stable and pure DC input voltage, and significantly improving the operating status of the user-side equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic flow chart of a voltage control method for a voltage regulator based on an adaptive filter proposed by the present invention; Figure 2 The present invention provides a block flow chart of a voltage control method for a voltage regulator based on an adaptive filter. DETAILED DESCRIPTION

[0018] 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.

[0019] Abbreviations involved: Pulse Width Modulation: Pulse Width Modulation, PWM Normalized Least Mean Square: Normalized Least Mean Square, NLMS.

[0020] Example 1

[0021] This embodiment provides a voltage control method for a voltage regulator based on an adaptive filter, such as Figure 1 As shown, the following steps are included.

[0022] S1. Initialize filter parameters and set expected signal.

[0023] After the source side AC voltage is rectified, the DC voltage is transmitted through the transmission line, filtered by the user side filter, and then enters the inverter module to output to the load. The voltage stabilizer coordinates the work of the filter and the inverter module to ensure the stability of the output voltage on the load side. The voltage stabilizer includes an inverter and a filter. Set the initial weight vector and step factor of the filter to control the speed of weight update and convergence stability. The initial parameter selection needs to be reasonably configured according to the noise characteristics of the system and the target output accuracy.

[0024] The filter parameters include the filter order, weight vector and step factor. These parameters are the basis for the normal operation of the filter. The filter order matches the filtering effect of the filter. The filter order determines its complexity and response speed. The higher the order, the better the filtering effect, but the corresponding calculation burden will also increase. The order should be set reasonably according to the application requirements during initialization. The weight vector is the core parameter in the filter output calculation. By continuously updating the weights, the filter can adapt to the changes in the input signal, thereby reducing the system error. The step factor determines the speed at which the algorithm updates the weight vector. The larger the step factor, the faster the weight update speed and the faster the system response, but too large a step factor may cause system oscillation or instability, so it needs to be set reasonably.

[0025] After initialization, set the expected signal. The expected signal represents the target output that the system should achieve at each moment. It is usually a reference value pre-set according to the control requirements of the system. After the expected signal is set, it can provide a basis for subsequent error calculation and control signal generation.

[0026] S2. Obtain the DC voltage of the transmission line, and obtain the output signal of the filter according to the weight vector of the filter and the DC voltage.

[0027] The DC voltage of the current transmission line is collected, the collected DC voltage is input into the filter, and the output signal of the filter is calculated by the current weight vector.

[0028] The output signal of the filter is: , In the formula, is the output signal of the filter, For the n The discretized DC voltage input signal at time instant, is the weight vector of the filter.

[0029] The weight vector of the filter is: , In the formula, are the components in the weight vector, corresponding to the weights of the filter.

[0030] S3. Obtain an error signal according to the output signal of the filter and the expected signal, and adjust the output voltage of the regulator according to the error signal.

[0031] The filter output signal is compared with the expected signal and the error signal is calculated.

[0032] The error signal is: , In the formula, is the error signal, is the output signal of the filter, is the expected signal.

[0033] Check whether the error signal meets the specific accuracy requirements, that is, determine whether the error is small enough. If the error signal meets the accuracy requirements, it means that the output signal is close to the expected signal. The current filter output signal is output and transmitted to the inverter. The inverter switch state is adjusted through PWM control according to the output signal, thereby adjusting the output voltage.

[0034] If the error signal does not meet the accuracy requirements, it enters the parameter update phase, such as Figure 2 As shown in the figure, first, the step factor is dynamically adjusted according to the input signal and error signal of the filter through the NLMS algorithm, so that the step factor is adjusted adaptively, thereby ensuring that it can converge to the expected value quickly. Then, the weight vector of the filter is updated in real time using the dynamically adjusted step factor and error signal, and then the output signal of the filter is adjusted. When the error signal meets the accuracy requirements, the switching state of the inverter is adjusted through PWM control according to the output signal, and then the output voltage of the regulator is adjusted.

[0035] The input signal of the filter includes harmonics and high-frequency noise. The input signal vector of the input signal is: , In the formula, For the n The discretized DC voltage input signal at time instant, M is the filter order.

[0036] After each weight update, the time index k and n Perform an increment operation and return to the sampling stage to continue a new round of sampling and error calculation until the system output signal reaches the expected accuracy.

[0037] When the error meets the accuracy requirement, the algorithm outputs the current filter output signal and passes it to the inverter's PWM control algorithm. According to the output signal, the inverter's switching state is adjusted through PWM control, and then the output voltage is adjusted to achieve stable control of the output voltage.

[0038] The design of the adaptive filter needs to have real-time and efficient harmonic suppression capabilities to cope with noise and harmonics in the flexible DC transmission process. The input signal of the adaptive filter is used to represent the output AC voltage of the AC low-voltage regulator, including harmonics and high-frequency noise; the expected signal is used to represent the ideal regulator output signal, usually a sine wave.

[0039] In the standard LMS algorithm, the step size factor is fixed, which can cause the filter to perform poorly under different input signal conditions. A step size factor that is too large can cause system instability, while a step size factor that is too small can slow down the convergence speed. To this end, we have improved the step size factor optimization method so that the step size factor can be adjusted adaptively according to the situation.

[0040] First, consider different step size adjustment methods. When using normalized NLMS, the step size factor is adjusted according to the energy of the input signal to maintain stability. The step size factor of the NLMS algorithm is determined as follows: , in, is a constant, usually taking a value between Between, the initial ; It is a positive number that prevents the denominator from being zero. It can be a very small number, such as 0.001; Represents the energy of the input signal vector. The optimized weight vector update formula is: , In the formula, is the step size factor, is the error signal, is the input signal vector.

[0041] When the dynamic step factor adjustment method is used, the step factor is adaptively adjusted according to the error signal. The step factor can be dynamically adjusted according to the size of the error to achieve a balance between fast convergence and stability. The specific implementation is: , In the formula, and are the minimum and maximum values ​​of the step factor, respectively. This dynamic adjustment method can ensure that when the error is large, there is a larger step factor, which speeds up the convergence speed; when the error is small, there is a smaller step factor, which improves the stability of the system.

[0042] Choose the appropriate filter order. The filter order directly affects the performance and complexity of the filter. If the order is too small, the filter will not be able to effectively suppress all harmonic components, while if the order is too large, the calculation amount will increase and may cause overfitting. Choosing the appropriate order requires comprehensive consideration of three factors: ① Consider the signal frequency content and the filter order. M It needs to be large enough to cover possible harmonics and noise components in the input signal. If the harmonic frequency is high, a larger M ;② Consider the real-time requirements of the system. If the system requires high real-time performance, then MIt should not be too large to avoid excessive computational complexity; ③ Refer to experience for selection. In practical applications, the order M It can be adjusted through experiments and finally determined according to the filtering effect. According to the above method, the order of the filter selected in this embodiment is 24.

[0043] The step size factor in the NLMS algorithm is mainly based on the input signal energy adjustment, without fully considering the change of the error signal. In order to further improve the performance of the adaptive filter, the design introduces a dynamic step size factor, which combines the size of the error signal so that it can be adjusted according to both the input signal and the error signal. Combining the ideas of NLMS and the dynamic step size factor, the step size factor is obtained as follows: , In the formula, is a constant, usually taking a value between Between, the initial ; It is a positive number that prevents the denominator from being zero. It can be a very small number, such as 0.001; represents the energy of the input signal vector, is the error signal, is the maximum value of the error.

[0044] This design can adaptively adjust the step size factor according to the energy of the input signal and the size of the error, thereby maintaining the stability of the system while ensuring the convergence speed.

[0045] Example 2

[0046] This embodiment provides a voltage control system for a voltage regulator based on an adaptive filter, including: Initialization module, used to initialize filter parameters and set expected signals; An output signal acquisition module is used to acquire a DC voltage and obtain an output signal of the filter according to a weight vector of the filter and the DC voltage; The voltage regulation module is used to obtain an error signal according to the output signal of the filter and the expected signal, and adjust the output voltage of the regulator according to the error signal: If the error signal meets the accuracy requirement, the current filter output signal is transmitted to the inverter, and the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the voltage regulator; If the error signal does not meet the accuracy requirements, the NLMS algorithm and the dynamic step factor method are combined to dynamically adjust the step factor according to the input signal and error signal of the filter. The weight vector of the filter is updated in real time according to the dynamically adjusted step factor and the error signal, and then the output signal of the filter is adjusted. When the error signal meets the accuracy requirements, the switching state of the inverter is adjusted through PWM control according to the output signal, and then the output voltage of the regulator is adjusted.

[0047] The rest is the same as in Example 1.

[0048] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A voltage control method for a voltage regulator based on an adaptive filter, wherein the voltage regulator comprises an inverter and a filter, characterized in that: The following steps are involved: Initialize filter parameters and set expected signal; Acquire a DC voltage of the transmission line, and obtain an output signal of the filter according to a weight vector of the filter and the DC voltage; An error signal is obtained according to the output signal of the filter and the expected signal, and the output voltage of the voltage regulator is adjusted according to the error signal: If the error signal meets the accuracy requirement, the current filter output signal is transmitted to the inverter, and the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the voltage regulator; If the error signal does not meet the accuracy requirement, the step factor is dynamically adjusted according to the input signal and the error signal of the filter, and the weight vector of the filter is updated in real time according to the dynamically adjusted step factor and the error signal, thereby adjusting the output signal of the filter. When the error signal meets the accuracy requirement, the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the regulator.

2. The voltage control method of a voltage regulator based on an adaptive filter according to claim 1, characterized in that: The filter parameters include filter order, weight vector and step factor.

3. The voltage control method of a voltage regulator based on an adaptive filter according to claim 2, characterized in that: The filter order matches the filtering effect of the filter.

4. The voltage control method of a voltage regulator based on an adaptive filter according to claim 2, characterized in that: The step factor matches the update speed of the weight vector.

5. The voltage control method of a voltage regulator based on an adaptive filter according to claim 1, characterized in that: The output signal of the filter is: ， In the formula, is the output signal of the filter, For the n The discretized DC voltage input signal at time instant, is the weight vector of the filter.

6. The voltage control method of a voltage regulator based on an adaptive filter according to claim 1, characterized in that: The error signal is: ， In the formula, is the error signal, is the output signal of the filter, is the expected signal.

7. The voltage control method of a voltage regulator based on an adaptive filter according to claim 1, characterized in that: The input signal to the filter includes harmonics and high frequency noise.

8. The voltage control method of a voltage regulator based on an adaptive filter according to claim 1, characterized in that: The dynamic adjustment formula of the step factor is: ， In the formula, is a constant, with a value of between; is a positive number that prevents the denominator from being zero; represents the energy of the input signal vector, is the error signal, is the maximum value of the error.

9. The voltage control method of a voltage regulator based on an adaptive filter according to claim 1, characterized in that: The updating formula of the weight vector is: ， In the formula, is the step size factor, is the error signal, is the input signal vector.

10. A voltage control system for a voltage regulator based on an adaptive filter, characterized in that: include: Initialization module, used to initialize filter parameters and set expected signals; An output signal acquisition module, used to acquire a DC voltage, and obtain an output signal of the filter according to a weight vector of the filter and the DC voltage; A voltage regulating module, used to obtain an error signal according to the output signal of the filter and the expected signal, and to adjust the output voltage of the regulator according to the error signal: If the error signal meets the accuracy requirement, the current filter output signal is transmitted to the inverter, and the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the voltage regulator; If the error signal does not meet the accuracy requirement, the step factor is dynamically adjusted according to the input signal and the error signal of the filter, and the weight vector of the filter is updated in real time according to the dynamically adjusted step factor and the error signal, thereby adjusting the output signal of the filter. When the error signal meets the accuracy requirement, the switching state of the inverter is adjusted through PWM control according to the output signal, thereby adjusting the output voltage of the regulator.

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