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The electromagnetic frequency regulator (EFR) device has proven to be an attractive solution for driving grid-connected electrical generators in distributed generation (DG) systems based on renewable energy sources (RES). However, the dynamic characteristic of the EFR has not yet been discussed for cases where its parameters vary from the nominal values. To evaluate this issue, this paper proposes a method for transient and steady-state performance analysis applied to the EFR device considering parametric variations. To perform this analysis, a dynamic model of the EFR device is derived, and its dynamic characteristics are discussed. Based on this model, the system’s controller gains are designed by using the root-locus method (RLM) to obtain the desired dynamic performance. Then, a sensitivity analysis of the closed-loop poles under the effect of parameters variation is performed. In addition, the paper also presents an analysis of the EFR-based system operating with the designed controllers. The proposed theoretical analysis is assessed using simulation and experimental results. The simulation program was developed using a Matlab/Simulink platform, while the experimental results were obtained through a laboratory setup emulating the EFR-based system.

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Because of the high penetration of distributed generation (DG) systems based on renewable energy sources (RES), it is necessary to develop control techniques for improving support to grid frequency and voltage from this kind of generation. Among the solutions proposed in the literature, the virtual synchronous generator (VSG) concept has proven to be an attractive solution to interconnect DG units to the power grid. However, the dynamic behavior of the VSG has not yet been discussed for cases in which line impedance parameters varies in relation to their rated values. To evaluate this issue, in this work a dynamic model of VSG power flow has been derived and its dynamic characteristics discussed. Based on this model, the parameters for VSG controllers are designed by using root-locus method (RLM) in order to realize desired dynamic performance. Then the VSG dynamic performance under line impedance variation eect is assessed. Finally, simulation results demonstrated theoretical analysis and parameters design method.

Second-order systems are those whose models can be written by a second-order differential equation. That is, they are those that have two poles. The present article proposes an approach to solve the output feedback control with eigenvalues for second-order systems using Sylvester equations. The matrices are prescribed in advance and depend greatly on the controllability conditions, being assigned the system's observability eigenvalues. Furthermore, the real-value spectral decomposition T (λ) is explored to establish conditions so that the feedback gain matrices do not overflow over the eigenvalue assignment. However, it should be noted that the proposed algorithms may present complex computational problems. Two theorems were presented using Sylvester equations. The algorithms were implemented based on Sylvester equations, and examples were presented with their conclusions.