Uma contribuição ao controle para estabilização de conversores em microrredes de energia utilizando o conceito de máquina síncrona virtual

Abstract

With the widespread use of renewable energy, the electrical systems begin to experience a new model, the Distributed Generation (DG). Thus, there is a scenario that signals a paradigm shift, from centralized generation based on large power plants to a decentralized model with several small and medium-sized generators units. Synchronous machines used in large power plants contribute to the stability of the power system through the energy stored in the rotor of the machine due to rotational inertia. Because this phenomenon, the system has a greater or lesser time response, depending on the inertia of the individual machine, being able to damp the disorders caused by several factors, such as connection and disconnection of generators on the network, connection and disconnection of loads , etc. The overall stability of the system depends on the contribution of all machines connected to the power system by the sum of the individual moments of inertia of each machine. Since DG units uses electronic converters as an interface between the source and distribution network. Generally, small DG units alone will not compromise the safe operation of the electrical system. Thus, the interactions between DG unit and a conventional electrical system can be neglected. However, with the penetration of GD in the electrical system, the overall dynamics of the power system can be significantly affected. Given the increased use of electronic interfaces (EI) for power generation, one of the biggest challenges to the future of power systems is the significant reduction of the electrical equivalent of the total rotational inertia of the system, which may result in a degradation system stability. In this context, the Virtual synchronous machines become important because of its beneficial characteristics similar to the actual machines. Further, similarly, the use of additional stabilizers signals in order to improve the dynamics of the system is possible. This dissertation proposed two dynamic stabilizers, one based on Sliding Mode Control (SMC) and another based on Model Reference Adaptative Control (MRAC).