Modeling and Harmonic Impact Mitigation of Grid-Connected SCIG Driven by an Electromagnetic Frequency Regulator

Abstract

The power quality analysis is an essential issue in the integration of distributed energy resources to the grid. Recent standards regulate the harmonics disturbances due to the increasing penetration of intermittent energy sources interconnected with the grid employing power converters. This paper aims to analyze the power quality of an interconnected wind turbine system based on a Squirrel Cage Induction Generator (SCIG) driven by an Electromagnetic Frequency Regulator (EFR). The steady state of the EFR harmonic model is developed in the stationary frame based on the conventional induction generator modeling, which allows the study of the harmonic disturbances in the electrical and mechanical variables due to the PWM inverter of the EFR’s armature voltage. There is no electrical connection between the EFR and SCIG, and the results show that the inherent system inertia contributes to the mitigation of the harmonic content at the grid side generated by the switching. In addition to the steady-state results, the Total Rated Distortion (TRD), which considers the harmonics and interharmonics components, was computed and presented a good performance compared to the IEEE 1547 standard and real data extracted of a single Doubly Fed Induction Generator (DFIG). Finally, the harmonic performance of the proposed system was evaluated considering the impact of the equivalent Thevenin impedance of the grid at the Point of Common Coupling (PCC).

Fuzzy Artificial Intelligence Based Control Strategy Applied to an Electromagnetic Frequency Regulator in Wind Generation Systems

“…For the graphical analysis and the analysis of transient regime parameters, the indices controller performance are evaluated in accordance with the equations ( 13) and ( 14) , in the section (5.2.4). The indices values calculated in the synchronous generator traction scenario empty, with both closed-loop control strategies, are summarized in the Table (12). According to Table (12), the conventional speed regulation obtained higher values for the accumulated error and for the error in relation to the time when compared to fuzzy regulation indices.…”

“…The indices values calculated in the synchronous generator traction scenario empty, with both closed-loop control strategies, are summarized in the Table (12). According to Table (12), the conventional speed regulation obtained higher values for the accumulated error and for the error in relation to the time when compared to fuzzy regulation indices. The absence of overshoot, together with the reduced t s due to fuzzy control, it causes a reduction average of 40.8% of the performance indicators in relation to the conventional control.…”

“…After implementing the controller inputs, it was necessary to design the functions output suggestion for each of the angles, as illustrated in the Table (6). The rules of inference implemented follow the equation (12), with n = 1,2,• • • ,9:…”

“…Furthermore, as the converter has no connection to the grid, this topology proved to be more effective in withstanding a severe short circuit at the induction generator terminals than a conventional doubly-fed induction generator (DFIG) topology. Subsequently, a power quality analysis applied to the wind generation topology discussed in [11] was proposed by [12]. The authors concluded that the high-frequency components of the voltage generated in an EFR-based system are naturally attenuated by the inertia inherent in the EFR-SCIG mechanical system, which results in an advantage compared to DFIG wind generation and permanent magnet synchronous generator (PMSG) topologies.…”

Performance Analysis of an Electromagnetic Frequency Regulator under Parametric Variations for Wind System Applications

“…In addition, RES-based generation systems are usually connected to the grid through power converters, which can contribute to the increase of harmonic components in the voltages and currents generated. In order to overcome these problems, the use of an electromagnetic frequency regulator (EFR) to drive grid-connect electrical generators was proposed in the literature [11][12][13][14][15][16]. The EFR device consists of a modified induction machine, whose conventional armature mass can rotate, powered by a wind turbine or any other system that can impose a mechanical torque on its axis, as illustrated in Figure 1.…”