Optimization of social welfare and transmission losses in offshore MTDC networks through multi-objective genetic algorithm

A multi-objective approach, for an envisioned future DC independent system operator (ISO), on how to optimally operate an offshore multi-terminal DC network is presented in this paper. A pool market is used, in which the ISO receives the bids, of both producers and consumers connected to the offshore network, and determines the electricity spot price. A trade-off between maximization of the social welfare and the minimization of transmission losses is analyzed. The offshore multi-terminal DC (MTDC) network here implemented is based on recent studies [1]. The multi-objective optimization algorithm (MOOA) determines an optimal power flow (OPF), which guarantees the network constrains - e.g. DC voltages boundaries, maximum DC cable current and power produced at the offshore wind farms - as defined by the ISO are all respected. Even on DC Networks the system losses, capitalized over a year, can be in the range of tenths of millions of euros [2]. Consequently, a fair power losses allocation among loads and generators has an important impact on their benefits. Therefore, a losses allocation technique is implemented in the algorithm. System security is also taken into consideration. In order to enhance the DC system stability with regard to predictable changes - demand and generation evolution - and unpredictable events - e.g. an outage at of one of the DC voltage controlling stations - the results of the OPF are also tested to make sure that the offshore network always remains at least N-1 secure [3].