Ensuring the provision of the increasing power consumption and maintaining the power quality (PQ) are considered to be the major challenges for electrical traction substations (TSSs) due to their dynamic characteristics, which render their power demand and electrical behavior to be highly complex. Solar photovoltaics (PVs) and battery energy storage systems (BESS) can be reliable options for integration with the TSSs, the prerequisite, however, is to devise the appropriate approaches for the demand management (DM) and maintaining the PQ of such a system. In this article, a strategy is proposed for the optimal technoeconomic operation of the TSSs using a sequential decision-making process (SDMP). In the first layer, the DM is formulated so that it can address the requirements of the integrated system and the uncertainties. The second layer optimizes the limited capacity of the PV/BESS converters for the mitigation of the unbalances and the reactive power compensation. Moreover, a comprehensive modeling framework incorporating the SDMP is presented that lends itself to use as a robust platform for the realistic modeling of the TSSs, BESSs, and PV systems. The framework is utilized to demonstrate the effectiveness of the proposed SDMP for both the DM and improving the PQ of the TSS, which are validated using different case studies.