HVDC multi-infeed analysis of the Brazilian transmission system and possible mitigation methods

The Brazilian transmission system is facing challenging problems with the distance between its generation areas and consumer centers that will be partly solved by the use of HVDC point-to-point systems. In the near future, the southeast subsystem will have a large amount of power injected through HVDC Systems in multiple points with relatively close electrical proximity. Therefore, the effects of a multi-infeed system are expected to influence the performance and operation of the network. Extensive studies and simulations will play an important role in determining the extension of the interactions among HVDC converters and determine if such interactions cause multiple commutation failures, thus disturbing the dynamic stability of the system. The use of CCC (Capacitor Commutated Converter) HVDC systems will also be assessed and is expected to diminish the need for a strong AC network (high short circuit level) and, therefore, mitigate multi-infeed interactions. The southeast subsystem of the Brazilian Power System currently has four LCC inverters, two of them belong to the Madeira power plant and the other two are from the Itaipu power plant. By the year 2024, four other HVDC systems will be arriving in the same region. This paper discusses the HVDC multi-infeed phenomena regarding the relevance of using synchronous machine models to represent important power plants and the application of mitigation methods regarding the 2020 network model, where six HVDC links will be present.