The Brazilian Interconnected Power System (BIPS) is undergoing a structural transformation driven by the expansion of wind, solar photovoltaic, and micro- and mini-distributed generation (MMDG). This transformation is based on the superposition of a large fleet of inverter-based resources (IBRs) onto a hydro-dominated system, in which reservoir hydropower remains the main source of flexibility. This paper examines the operational challenges that follow and how they were transformed into grid code requirements. These challenges became concrete in the partial blackout of 15 August 2023, whose investigation found that wind and photovoltaic plants did not perform as their simulation models predicted. The regulatory response made model representativeness a binding requirement, and validated models are now a condition to obtain the authorization to begin commercial operation. The paper describes the resulting connection requirements, modeling obligations and compliance procedures, and the emerging grid-forming requirements for battery energy storage. These instruments are available only in Portuguese, by presenting them in a single text, the paper aims to make the Brazilian integration framework accessible to the international community of manufacturers, whose prospects in Brazil now include a record of project registrations for battery energy storage systems and more than 134 GW of offshore wind projects seeking environmental licensing