“…Hence, the dual solutions obtained in consecutive iterations tend to vary significantly, which also leads to slow convergence in the primal problem. To improve the stability, the column generation scheme presented in Section 3 is modified to include a boxstep restriction (Marsten et al, 1975) on the individual dual variables, so that each new dual point is kept close to the previous one (see also, e.g., du Merle et al, 1999;Larsson et al, 2004;Westerlund et al, 2006). For the dual problem of the RLPM presented in Section 3.1, we choose to include box constraints only for the dual variables y nt , since the values of the dual variables v u are uniquely determined by the values of y nt due to the structure of the constraints.…”