Parameter-varying Filter Research Articles

Local Frequency Restoration for Droop-Controlled Parallel Inverters in Islanded Microgrids

In islanded microgrids, voltage source inverters working in parallel are expected to provide regulation of the local frequency while granting active power sharing. This paper presents a local control approach at each inverter based on an event-driven operation of a parameter-varying filter. It ensures perfect active power sharing and controllable accuracy for frequency restoration without requiring the exchange of control data between inverters over the communication network. This paper includes stability analysis and design guidelines for the control parameters using a modeling approach that considers the interaction between inverters. Selected experimental results on a three-inverter laboratory microgrid corroborate the effectiveness of the proposed control scheme, and outlines its advantages with respect to previous similar schemes and the performance cost that implies not using communications.

A Second-Order Lowpass Parameter-Varying Filter Based on the Interconnection of First-Order Stages

In recent years, a new class of filters known as parameter-varying filters has been proposed. These filters are characterized by having a transient response of reduced duration while preserving their frequency response properties. The reduction of the transient response of these filters is a consequence of the automatic adjustment of their parameters. These filters may be used in signal processing applications in which the influence of the transient behavior of the filter is seen as an unwanted component of the filter output. In this article, a second-order lowpass parameter-varying filter based on the cascade of first-order parameter-varying stages is presented. The stability properties of the proposed filter, and particularly its bounded-input, bounded-output stability, are verified using a linear time-varying model which accurately represents its behavior when it is subject to the variation of its parameters. The parameters of the filter are varied according to a predefined control strategy. Simulation results confirm the filter capabilities to shorten the duration of its transient behavior when its parameters are varied through the action of a nonlinear control loop.

Analytical Synthesis of Parameter-Varying Filter of Constant Component with Application to Switching Systems

In this paper, we propose a concept of a continuous-time filter of constant component that exhibits a very short response in the time domain if compared to the traditio nal time-invariant filter. The improvement of the filter dynamics was achieved as a result of the time-varying p arameters which were introduced to the filter structure. Such a designed filter is then applied in a system whic h switches many distorted signals which should be filtered as fast as possible. The paper is of review nature and presents both a theoretical background of the proposed filter and the results of simulations.

A first-order parameter-varying filter using dynamic translinear techniques

Abstract In this article, a first-order parameter-varying filter based on dynamic translinear techniques is presented. The proposed filter has a reduced time response which is a consequence of the strategy considered for the variation of its 3 dB cutoff frequency. Computer simulations confirm the correct operation of the filter.