Controle inercial e de frequência baseado em gerador síncrono virtual aplicado à geração fotovoltaica de grande porte para o suporte ao restabelecimento de sistemas de potência

Abstract

The renewable generation growth, which includes photovoltaic power plants, has posed challenges for the planning and operation of contemporary power systems. The insertion of generation based on fully-rated converters, such as photovoltaic generation, makes the black-start of power systems more difficult due to the low equivalent inertia of the system, the performance deterioration of the primary frequency control, the reduced number of black-start units, and the energization of large loads. In this context, this work proposes an operational and control approach for centralized photovoltaic generation to provide inertial response and frequency control support only during the bulk power systems restoration process. The proposed operational strategy creates a power margin by means of the de-loaded operation of the photovoltaic generation. The proposed control, based on virtual synchronous generator and droop-type controller, uses this power margin to provide inertial response and primary frequency control support only during the system restoration process. The work also proposes an analytical formulation to assess the impact of the operating point of photovoltaic modules on the dynamics of photovoltaic units. A study involving the linear model of the system is also carried out to identify the system parameters that most affect the system frequency during the operation of the photovoltaic units at the maximum power point of the photovoltaic modules. The results obtained by means of computational simulations in the time domain have shown that photovoltaic generation is capable of providing support to the black-start of power systems, significantly improving the inertial response and the frequency control of the system. The performed dynamic analyses have shown that the operational region of the photovoltaic modules significantly affects the dynamics of the power balance in the photovoltaic unit and, consequently, the dynamics of the load pick-up of the photovoltaic modules. The performed linear analyses have shown that the parameters of the PI controller used to regulate the DC-link voltage significantly affect the dynamics of the system's frequency and, consequently, the stability of the system.