Good Filtering Capability Research Articles

Design-Oriented Study of the Orthogonal Vector-Based Linear Kalman Filter: Enhancements and Applications

This article focuses on the orthogonal vector-based linear Kalman filter (LKF) and provides a systematic design guideline. To optimize the steady-state performance, a parameter tuning algorithm and a decoupling method are proposed. In this way, one can tune the Kalman gains individually and reduce the coupling between harmonic models. A stability analysis is also conducted in this part, which helps to properly design the steady state of the LKF. To optimize the dynamic performance and take the maximum benefit out of the adaptive mechanism of the LKF, a dynamic tracking algorithm is proposed in this article. Compared with the conventional filtering/synchronization methods, the proposed LKF can achieve a relatively fast dynamic response, small overshoot/peak errors, and good filtering capability. These advantages are verified by experiments.

Modeling and frequency characteristic analysis of DSOGI-PLL in dq reference frame

Dual second-order generalized integrator phase-locked loop (DSOGI-PLL) is widely used in grid-connected system for grid synchronization because of its simple implementation and good filtering capability. However, the frequency characteristics of DSOGI-PLL affect the impedance modeling of the system, which in turn affect the impedance-based stability analysis. In order to improve the accuracy of system modeling, in this paper, the equivalent transfer function of positive-sequence calculator (PSC) block constructed in αβ reference frame in DSOGI-PLL is presented in dq reference frame, where the relationship between DSOGI-PLL and traditional synchronous reference frame PLL (SRF-PLL) small-signal model is investigated. Then, based on the established model, DSOGI-PLL and SRF-PLL are compared from the tracking characteristics and robustness characteristics. It is further demonstrated that DSOGI-PLL is able to improve the robustness performance of PLL while maintaining the same tracking performance as SRF-PLL. Finally, simulation results are presented to validate the established model and frequency characteristic analysis.

Electrical Impedance Spectroscopy for Real-Time Monitoring of the Life Cycle of Graphene Nanoplatelets Filters for Some Organic Industrial Pollutants

This article proposes an approach for smart monitoring of the life cycle of innovative graphene-based filters for water remediation in the presence of pollutants. The measurement technique is based on suitable figures of merit that analyze the time variation of the electrical impedance frequency spectrum. The proposed study considers the remediation of two toxic industrial pollutants, such as the acetonitrile and the 2,4-dichlorophenol. The contribution of this article is twofold. The first is the demonstration of a reliable monitoring setup that is able, for the selected use cases, to correlate in real time the behavior of the electrical impedance of the filter to its status, defined as “absence of pollutants” and/or “saturation.” The second contribution is the proposal of suitable figures of merit, based on measurement of the impedance frequency spectrum, able to increase the measurement sensitivity and the reliability and to mitigate some sources of uncertainty typically associated with these kinds of setups and measurements. Results show that the proposed graphene-based filters combine very good filtering capability and high sensitivity of the electrical impedance to the considered pollutants. These results suggest further investigations with other pollutants and the potential use of this technique for the predictive maintenance of the water filters in industrial applications, by endowing the graphene filters of smart sensing devices.

A Modified DSC-Based Grid Synchronization Method for a High Renewable Penetrated Power System Under Distorted Voltage Conditions

With the increasing penetration of renewable energy, a weak grid with declining inertia and distorted voltage conditions becomes a significant problem for wind and solar energy integration. Grid frequency is prone to deviate from its nominal value. Grid voltages become more easily polluted by unbalanced and harmonic components. Grid synchronization technique, as a significant method used in wind and solar energy grid-connected converters, can easily become ineffective. As probably the most widespread grid synchronization technique, phase-locked loop (PLL) is required to detect the grid frequency and phase rapidly and precisely even under such undesired conditions. While the amount of filtering techniques can remove disturbances, they also deteriorate the dynamic performance of PLL, which may not meet the standard requirements of grid codes. The objective of this paper is to propose an effective PLL to tackle this challenge. The proposed PLL is based on quasi-type-1 PLL (QT1-PLL), which provides a good filtering capability by using a moving average filter (MAF). To accelerate the transient behavior when disturbance occurs, a modified delay signal cancellation (DSC) operator is proposed and incorporated into the filtering stage of QT1-PLL. By using modified DSCs and MAFs in a cascaded way, the settling time of the proposed method is reduced to around one cycle of grid fundamental frequency without degrading any disturbance rejection capability. To verify the performance, several test cases, which usually happen in high renewable penetrated power systems, are carried out to demonstrate the effectiveness of the proposed PLL.

Ka-band multilayered substrate integrated waveguide narrowband filter for system-in-package applications

In this article, a Ka-band narrowband multilayer bandpass filter (BPF) centered at 34.5 GHz is presented, where a hybrid structure of two substrate integrated waveguide (SIW) cavities with slots and CPW is used to meet the good filtering capability and compact size. Benefiting from the 3-D circuit layout, the proposed filter can effectively overcome a vital drawback of large circuit size of traditional filter, and be used in system-in-package application. The circuit size of the filter excluding feed lines is about 0.5λg by 0.5λg, where λg is the guided wavelength at the central frequency of 34.5GHz. Simulated results show that the filter has the 3dB bandwidth of 0.86 GHz (FBW = 2.5%) and insertion loss of 1.7 dB at central frequency. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1395–1398, 2016

A Class of Filtering Superoptimal Preconditioners for Highly Ill-Conditioned Linear Systems

Popular preconditioners for conjugate gradient methods often reveal poor regularization properties that make them useless for very ill-conditioned linear systems arising in inverse problems. Recent results have awakened the interest towards the Tyrtyshnikov superoptimal preconditioners since it has been demonstrated that they exhibit good filtering capabilities. Here, in order to improve the regularizing behaviour, we generalize the definition of superoptimal preconditioner. Later on, by means of this more general definition, we develop a particular family of preconditioners for Toeplitz highly ill-conditioned linear systems.

A PC based state estimator interfaced with a remote terminal unit placement algorithm

In this paper a new remote terminal unit (RTU) placement algorithm is presented. The objective of this algorithm is to place a minimum set of RTUs which satisfies three important constraints of the problem-observability, absence of critical measurements, and reliability requirements defined in terms of RTU loss. The problem is solved in a single stage. The results of this algorithm are interfaced with a linear programming (LP) state estimator. This estimator only uses the voltage measurements, and the active and reactive power flows in the lines for the development of the coupled state-estimation Jacobian H-matrix. The injection measurements are not currently included, though in practice they can be easily added to the estimator model. The inclusion of the injection measurements will enlarge the use of the presented algorithm. The RTU placement algorithm and its link with the LP estimator are tested on IEEE standard bus systems. Using the proposed RTU set, the test results presented show that the LP estimator has very good filtering capabilities when operated with or without bad data, and that the loss of any RTU does not have any significant impact on the solution.

Fast vector median filter based on Euclidean norm approximation

The vector median filter has good filtering capabilities; nevertheless, its huge computational complexity significantly limits its practical usability. A vector median filter based on a fast approximation of the Euclidean norm is presented. The proposed algorithm couples computational and filtering effectiveness, and it is well suited for hardware implementation. Theoretical and experimental results regarding both approximation error and speed improvement prove the validity of the proposed algorithm. >