bachelorThesis
Investigação de estruturas de controle para inversores monofásicos aplicados em geração distribuída
Fecha
2021-04-20Registro en:
PIVETA, Marcelo. Investigação de estruturas de controle para inversores monofásicos aplicados em geração distribuída. 2021. Trabalho de Conclusão de Curso (Engenharia de Elétrica) - Universidade Tecnológica Federal do Paraná (UTFPR), Pato Branco, 2021.
Autor
Piveta, Marcelo
Resumen
This work presents an investigation on control techniques for single-phase inverters applied in distributed generation, focusing on a comparative analysis of auxiliary stabilization structures and improvement of energy quality. Initially, the main stages of a typical distributed generation system are presented and discussed, in addition, a main control structure for this system is proposed, consisting of three components: synchronism system, reference current generation and current controller. Then, a literature review is presented regarding different auxiliary structures for the control of the distributed generation system: harmonic compensator, power grid parameter estimator, passive damping and active damping techniques based on digital filters and state variables feedback. Among the structures presented, some are selected and evaluated in a comparison, developed from results obtained in simulations in software PSIM. The main topics analyzed in the comparison are the effects of the auxiliary structures on the stability and energy quality of the distributed generation system. The harmonic compensator and the active damping based on the proportional feedback of the LCL filter capacitor’s current showed the best results for their purposes, energy quality and stability, respectively. The harmonic compensator was able to cause reductions of up to 4.82% in the THD of the output current of the DG system. The active damping based on the proportional feedback of the LCL filter capacitor’s current shows high damping capacity, moreover, in none of the cases analyzed for this structure the THD of the output current exceeded 4.57%. Passive damping has a reduced capacity of stabilizing the DG system, in addition, in some cases (non-linear local load), the THD of the output current exceeds the limits of the power quality standard (5%), reaching values of up to 8.42%. The active damping based on notch digital filter has a good capacity of stabilizing the GD system. However, the energy quality presents worse levels than those of the other damping structures in several scenarios analyzed, most notably in the case of local non-linear load, in which the THD of the output current reaches up to 17.82%. The power grid parameter estimator shows unsatisfactory and inconsistent results. The estimation error is very high for the resistive portion of the electrical power grid impedance, especially for cases of strong grid, where the real and estimated values differ by several orders of magnitude. For the inductive portion of the electrical grid impedance, the error is considerably less, reaching a maximum of 21.4%.