Comparative study of PR and PI controllers applied to an inverter of a DFIG based wind system for compensation of reactive power in distribution network

• Grant number: 18/06358-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2018
• End date: November 30, 2019
• Field of knowledge: Engineering - Electrical Engineering - Industrial Electronics, Electronic Systems and Controls
• Principal Investigator: André Luiz Andreoli
• Grantee: Vinícius Tavares Alves
• Host Institution: Faculdade de Engenharia (FE). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

The growing concern about the environment, triggered by climate change generated by global warming, and the technological development of society, which produces a significant increase in the demand for electricity, and the threat of the scarcity of natural resources on the planet, has intensified investment in the development of renewable energy sources. Among the main sources of energy, the wind energy obtained through wind turbines has stood out due to its economic viability with the other sources. Nowadays, generation systems based on Doubly Fed Induction Generators (DFIG) have been provided not only for the production of active energy but also have been shown as a viable alternative to its application as an element to improve the quality of energy of the electric system. In this configuration, the machine operates associated with a converter in a back-to-back configuration, with control meshes capable of controlling the active and reactive power of the system in the four operating quadrants. The control of the DFIG power components is obtained through the stator flux orientation, rotor flow or the mains voltage, using proportional-integral (PI) controllers. The proposed PR-proportional resonant controller has the ability to present relatively high gain at a given frequency (resonance frequency) and practically no gain at other frequencies. However, this controller is not able to override other harmonic components in the network. Harmonics in the current can be compensated by applying to the system additional PR controllers for each harmonic component (3rd, 5th, 7th and so on), so that the most significant harmonics are reduced or eliminated from the system, thus allowing a decrease in the THD of the distribution. The objective of this research is to study and implement an alternative proposal to control the reactive power on the side of the grid in a wind generator using a proportional-resonant controller (PR), tuned to the 1st, 5th, 7th, 11th, and 13th order components, replacing to the PI controllers already implemented and, later, to perform a comparative study of operational performance between the system using PR controllers developed in this research and the system using PI controllers previously implemented by other researchers.