CN-122017428-A - Reliable direct identification method for characteristic parameters of single-tuning filter

Abstract

The invention discloses a reliable direct identification method of a single-tuned filter characteristic parameter, which comprises the following steps: initializing a single tuning filter to be detected into a zero state, applying a direct current excitation source with constant amplitude to the single tuning filter to be detected, sampling and storing a single tuning filter current sequence, performing sliding average filtering treatment on a sample, calculating an identification element, calculating an identification basic parameter, calculating an identification characteristic quantity, and obtaining a single tuning filter characteristic parameter resistor R, an inductor L and a capacitor C; the invention takes the single-tuned filter as a detection object, monitors the characteristic parameters thereof in real time, builds a simulation model of the single-tuned filter, verifies the identification method of the characteristic parameters in the filter through experiments, and confirms the identification method of the invention on the premise of not disassembling and damaging the filter device by analyzing the experimental results, thereby accurately and reliably estimating the characteristic parameters of the single-tuned filter in the interference environment.

Inventors

• XIAO JIXUE
• WANG HUANG
• WANG RUI
• XIAO HANWEI
• XIE WEICHENG
• YIN YANG
• JIANG DAIJUN

Assignees

• 西华大学

Dates

Publication Date

20260512

Application Date

20260305

Claims (5)

1. 1. A reliable direct identification method of a single-tuning filter characteristic parameter is characterized by comprising the following steps: step one, enabling the input of a single-tuning filter to be detected to be zero, eliminating energy stored in the filter to enable the filter to be in a zero state, namely enabling the current output of the filter and the internal state of the filter to be equal to zero, and then preparing a direct-current voltage source with a constant amplitude of U 0 and a current acquisition system; Applying the direct-current voltage source prepared in the first step to the input end of the single-tuning filter to be detected, collecting the current i s (T) of the filter by using a prepared current collecting system, storing the current, wherein i (k) =i s (k·T s ) is a current value collected in a kth period, k=1, 2,3, and M and T s are sampling periods, and M is the number of samples; step three, carrying out sliding average filtering treatment on the sample i (k), and marking the treated sequence as h (k), namely Ω is the filter window width, k=1+0.5ω, 2+0.5 omega, 3+0.5 omega, once again, M ‒ is 0.5 ω; Calculating identification primitives sigma (bp, ep,0, 0), sigma (bp, ep,0, 1), sigma (bp, ep,0, 3), sigma (bp, ep,1, 1), sigma (bp, ep,1, 3) by using h (k), wherein bp and ep are respectively an h (k) starting point sequence number and an end point sequence number for acquiring the identification primitives; step five, calculating and identifying basic parameters u and v; Step six, calculating identification feature quantities alpha and beta; And step seven, obtaining the characteristic parameter resistor R, the inductance L and the capacitance C of the single-tuned filter.
2. 2. The method of claim 1, wherein in the fourth step, the calculation formulas of the identification elements σ (bp, ep,0, 0), σ (bp, ep,0, 1), σ (bp, ep,0, 3), σ (bp, ep,1, 1) and σ (bp, ep,1, 3) are: 。
3. 3. The method for reliably and directly identifying the characteristic parameters of the single tuned filter according to claim 1, wherein in the fifth step, the calculation formulas for identifying the basic parameters u and v are as follows: 。
4. 4. The method for reliably and directly identifying the characteristic parameters of the single tuned filter according to claim 1, wherein in the sixth step, the calculation formula of the identification characteristic quantities alpha and beta is as follows: Wherein phi is a difference coefficient.
5. 5. The method for reliably and directly identifying the characteristic parameters of the single-tuned filter according to claim 1, wherein in the seventh step, the calculation formulas of the characteristic parameter resistance R, the inductance L and the capacitance C of the single-tuned filter are as follows: , Wherein, p 1 、p 2 is the first characterization factor and the second characterization factor respectively, A is the cumulative ratio parameter, and gamma 1 、γ 2 is the first characterization parameter and the second characterization parameter respectively.

Description

Reliable direct identification method for characteristic parameters of single-tuning filter Technical Field The invention relates to the technical field of power system filter parameter detection, in particular to a reliable direct identification method for a single-tuned filter characteristic parameter. Background With the development of modernization of various industries of national economy, a large number of nonlinear loads mainly including various power electronic devices are increasingly and widely applied, and the problem of harmonic suppression is getting more and more attention. The single-tuning filter formed by connecting a filter reactor and a filter capacitor in series is a basic unit for forming a power system filter device. Along with the increase of the service time of the single-tuned filter and the change of the temperature of the working environment, the internal components of the single-tuned filter can correspondingly increase in temperature and can not work normally. In this case, the values of characteristic parameters of various kinds of components inside the filter may be changed and aged gradually, thereby impairing the filtering performance of the filter. Therefore, monitoring parameters of components in the single-tuning filter has very important practical significance for grasping the filtering performance of the single-tuning filter and reasonable and effective use of the single-tuning filter. However, single-tuned filter products are often packaged, and if the parameters are easily damaged by disassembly for detection, it is difficult to detect the parameters without disassembly. Thus, studies have been conducted. The filtering performance of the single-tuned filter actually depends on the values of three lumped basic element values, namely, characteristic parameters R, L, C, of the internal resistance, inductance and capacitance of the filter, and the parameters jointly determine the frequency characteristic of the single-tuned filter and characterize the filtering performance of the single-tuned filter. As shown in fig. 1, the equivalent circuit model of the conventional single-tuning filter is mainly formed by connecting a resistor R, an inductor L and a capacitor C in series, and has an input voltage u i (t), a capacitor voltage u c (t), a current i s (t), and a capacitor C: (1.1) From the circuit knowledge, it can be seen that: (1.2) the input voltage U i (t) is a step signal of magnitude U 0, namely: (1.3) Before t <0, i.e. before operation, there is no voltage input, i.e. u i (t) =0, the voltage across the capacitor is 0V, and the current flowing through the capacitor is 0A, i.e. the single-tuned filter is in zero state. When t is more than or equal to 0, the input voltage U i (t) of the single-tuned filter is a constant value U 0. The voltages u c (t) and the currents i s (t) in the time domain can be solved by the combination of (1.1) to (1.3). For a single tuned filter to be produced, it is difficult to measure u c (t) of the filter. The existing identification method of the characteristic parameters of the single-tuning filter generally can only play a role after the actual fault of the single-tuning filter has occurred, cannot predict or prevent the occurrence of the fault in advance, and cannot directly acquire the characteristic parameters in the single-tuning filter. Still other identification methods only focus on the aging of the capacitor, ignoring the aging of other components such as inductance and resistance in the device. In the existing nonlinear identification method, the calculation quality is greatly affected by the initial point, and a local optimal point rather than a whole optimal point can be obtained, so that a large error is generated. The direct identification method proposed at present has weak dry resistance, and when the noise/signal ratio is 15.5%, the identification relative error of the characteristic parameters reaches about 2%. The interference ratio is large in many application sites, and the noise/signal ratio is often higher than 20%. Therefore, the invention provides a reliable direct identification method of the characteristic parameters of the single-tuned filter to solve the problems in the prior art. Disclosure of Invention Aiming at the problems, the invention aims to provide a reliable direct identification method of the characteristic parameters of the single-tuning filter, and solves the problems that most of the existing identification methods of the characteristic parameters of the single-tuning filter cannot predict or prevent faults in advance, the characteristic parameters in the single-tuning filter cannot be directly obtained, the ageing conditions of other elements such as inductors and/or resistors in the device are ignored, the anti-interference capability is weak, and the error is large. In order to achieve the aim of the invention, the invention is realized by the following technical scheme that the reliable dire