Stability and Reserve Constraints in Optimal Dispatch Models

The United Nations Framework Convention on Climate Change (UNFCCC) is strongly committed to accelerating the transition of the power sector towards a high penetration of Variable Renewable Energy (VRE) sources, with the goal of reducing global dependence on fossil fuels for power generation. However, this transition poses a significant challenge, as the increasing VRE share in power systems gradually decreases their rotational inertia. This reduction in rotational inertia negatively impacts the stability and safety of power systems, creating new operational challenges. To address this, transmission system operators (TSO) have defined strategies to compensate for unexpected imbalances between load and generation by contracting primary and secondary reserves. Nevertheless, a method that compensates for the inertial response excursion after a disturbance adapted to these tools has not yet been fully identified. This work proposes a deterministic estimation of inertia constraint in UC/OD models. The Rate of change of Frequency (RoCoF) is estimated from an Optimal Dispatch model by considering the worst-case contingency in the test case. Then the lower inertia limit required to operate the system with stability is estimated. The estimation of the inertia limit is done offline the optimization and added as a new constraint in the UC/OD model. Finally, different scenarios of VRE penetration are defined to evaluate the impact of this new constraint with a sensitivity analysis. Results show that the proposed method can be complementary applied to UC/OD models to reduce the risk of unintended load shedding, which might lead to cascading failures and blackouts.ARES-CDD and ARES PRDBOL2022 programmes7. Affordable and clean energy13. Climate actio

Energy transition planning in developing countries: The case of Bolivian interconnected power system

The transition to a more environmentally friendly energy matrix has become one of the most important goals to control the climate change. Variable renewable energy sources (VRES) are a central low-carbon alternative but their variability and lower predictability require a flexible power system capable of balancing the variations. The aim of this paper is to determine a possible transition pathway to reach high penetrations of non-conventional renewable sources for Bolivia. To that aim, a Bolivian long-term scenario (2050 horizon) is developed based on the international targets, with the purpose to distribute economic resources optimally in the next 30 years. This is achieved by combining a unitcommitment and dispatch model with the forecast demand for the upcoming years, the already-known power system plan for the Bolivian system (5 years), and various scenarios of VRES deployment. For each scenario, the flexibility of the power generation system is evaluated in terms of energy balancing, transmission grid, system inertia, ancillary services requirement, and energy generation cost. Results indicate a need to add 8.31 GW of transmission lines, increase storage capacity, and enhanced ancillary services up to 73.31TWh (in particular frequency containment reserve) in the next 30 years. Finally, the environmental and economic gains are evaluated with comparison to the baseline it is found that the proposed system can reduce 62% of the CO2 emissions by 2050 with high penetration of VRES. This will result into significant economic savings for the country by enhancing natural gas exportations.Energy transition planning in developing countries: The case of Bolivian interconnected power syste