Estratégias para a mitigação de fluxo reverso em redes de distribuição com alta inserção de geração solar fotovoltaica

Abstract

The electric power sector has undergone significant changes in recent times due to the growing demand for a cleaner and more sustainable energy matrix. In line with this trend, the Brazilian government began encouraging energy generation by consumers themselves through the Legal Framework for Distributed Generation (Law No. 14,300/2022 from Brazil), which has made photovoltaic distributed generation a rising trend in Brazil. However, the expansion of distributed generation (DG) can lead to negative impacts on the grid, such as reverse power flow and overvoltage at system buses. This situation raises concerns for utility companies and motivates studies aimed at monitoring and mitigating these adverse effects. This study aims to propose strategies to mitigate reverse power flow in distribution networks with high photovoltaic generation penetration and to assess their impact on the electrical system. The research proposes three strategies for mitigating reverse flow: a battery energy storage system (BESS), an inverter-based Grid Zero control, and PV Curtailment, which consists of limiting the power injected by the modules with an inverter when an increase in bus voltage is detected. The proposed strategies were implemented in a distribution network in São Paulo using OpenDSS, an open-source software developed by Electric Power Research Institute (EPRI) that performs power flow analysis. The assessment of effects included the analysis of power flow through critical transformers, the substation, as well as the monitoring of bus voltages and network energy losses. The results demonstrate that the proposed strategies were effective in mitigating reverse power flow. Battery allocation yielded the best results, enabling the full use of energy generated by photovoltaic plants. The Grid Zero inverter curtailed part of the generation but was effective in mitigating reverse flow and presents a more economical alternative. PV Curtailment was the least effective in attenuating reverse flow, but managed to decrease the voltage rises in the nodes more efficiently than the other cases did.