Power flow control for an embedded HVDC link to integrate renewable energy in Brazil

Abstract

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.