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The power system long-term expansion planning is a computer-intensive problem as demands a varied set of studies especially considering the increasing deployment of intermittent renewables. In the case of the Brazilian power sector planning, the responsible institutions mostly use proprietary software. This paper presents the multiyear two-stage academic generation and transmission expansion planning software, called CARTHER, developed by the authors in order to provide the academy an open-source and non-commercial software, with a friendly interface and with several applications for expansion planning of hydrothermal systems with high intermittent renewables penetration. CARTHER is then calibrated for a case study in the Brazilian power sector, considering the most recent governmental goals for renewable energies for the horizons of 2030, 2040, 2050 and 2060. The results demonstrate the functionality and the qualitative capacity of CARTHER optimization under the expansion's criteria of flexibility and reliability in the face of the intermittent renewables penetration. [ABSTRACT FROM AUTHOR]

Brazil is a case of the achievement of a high share of wind energy integration to an interconnected power system in an emerging market. A series of successful energy supply programmes and a strong renewable-oriented finance framework implemented since 2002, have promoted alternative renewables – wind installed capacity increased over 22-fold from 927 MW in 2011 to 21 GW in 2022, reaching 11.77% of total procured power. From this, about 90% are concentrated in Brazil's least developed region, the Northeast, where wind investment should create jobs and propel socioeconomic development. Despite that, there is no studies specific assessing the regional and economy-wide effects of those programmes, gap that this paper aims to fill by applying the regional Computable General Equilibrium (CGE) model TERM-BR10. We assess that by modelling an alternative scenario for the period 2010-19 based on an official electricity matrix built in 2010, that projected 3.4 additional GW of wind power while not considering all the success of renewable policies, against the observed installed capacity expansion, where wind power was 3.7 times higher than what had been planned. Our results show that in the absence of renewable policies, Brazil would have faced economic losses such as GDP (−0.27%) and investment (−4.76%). The Northeast region would have been the most impacted in terms of GDP (−1.3%), real wage (−2.99%) and employment creation (−0.1%). We propose that such socioeconomic co-benefits are incorporated in energy planning, which could promote regional equality through renewable energy expansion. • Wind power capacity increased over 20-fold from 2011 to 2022. • 90% are in the poorest region where policies propel development and job creation. • Policy absence would entail a GDP loss of 0.27% nationally and of 1.3% in the region. • Negative impacts to labour market are mostly over skilled jobs. [ABSTRACT FROM AUTHOR]

• A new Angle Difference Controller to adapt the power order of embedded HVDC links. • Simulations with the proposed ADC in the official Brazilian Power System model. • Performance comparison of the ADC implemented in LCC HVDC link and VSC HVDC link. • A tutorial example to make it clear the appearance of loop flows in AC-DC systems. This paper discusses the power flow control of embedded HVDC links in the Brazilian grid, with special attention to the requirements of intermittent energy sources where frequent load changes are needed, including power reversal, and automated action is called for. Recently two North-South bipoles, 4000 MW each, ±800 kV, have entered into service, these being embedded in the grid and with separate receiving end converter stations. In this case "reverse" power flow is foreseen, but only on a seasonal basis when water flow is low at the North region. The increasing capacity in wind and solar energy, especially in the Northeast region and the possibility of a new embedded HVDC link to carry the surplus power from this region, call for an adaptable power setpoint in the DC links in order to avoid adverse effects as loop flows and increased losses. The paper investigates the use of angle difference control and proposes a new controller to mitigate those adverse effects. [ABSTRACT FROM AUTHOR]