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The renewable portfolio standard has been promoted in parallel with the reform of the electricity market, and the flexibility requirement of the power system has rapidly increased. To promote renewable energy consumption and improve power system flexibility, a bi-level optimal operation model of the electricity market is proposed. A probabilistic model of the flexibility requirement is established, considering the correlation between wind power, photovoltaic power, and load. A bi-level optimization model is established for the multi-markets; the upper and lower models represent the intra-provincial market and inter-provincial market models, respectively. To efficiently solve the model, it is transformed into a mixed-integer linear programming model using the Karush–Kuhn–Tucker condition and Lagrangian duality theory. The economy and flexibility of the model are verified using a provincial power grid as an example.

This study presents a generation expansion planning by incorporating the impacts of renewable energy on the generation mix. The wind–solar power output and its flexibility requirement are integrated into an optimization model to provide the realistic representation of wind and solar energy resources. The model is then used for the power system optimization planning of Jiangsu Province. A comparison of power demand, electricity price subsidies, and carbon emission intensity scenarios reveals the power planning scheme and optimization path for power system integrating increasing renewable energy. The results suggest that the installed capacity of renewable energy will increase from 21.6 to 133.2 GW in the baseline scenario during the planning period, with its share ranging from 17.9 to 53.7%. Solar photovoltaic power is expected to contribute 72% of renewable capacity and 39% of total capacity by 2050. The impact of electricity price subsidies on solar PV generation expansion is particularly significant. Additionally, the flexibility requirement of power systems can basically be satisfied with the available generation technologies; however, it would become severe if the flexibility requirement grows faster than the flexible generation.

Towards low-carbon energy systems, there are countries with ongoing plans for expanding their nuclear power capacity, and simultaneously advancing the role of variable renewable energy sources (RES), namely wind and solar energy. This crossroads of capital-intensive, baseload power production and uncontrollable, intermittent RES may entail new challenges in the optimal and economic operation of power systems. This study examines this case by hourly analysis of a national-level energy system with the EnergyPLAN modeling tool, coupled with wind integration simulations (including uncertainty) implemented using MATLAB. We evaluate the maximum feasible wind integration under different scenarios for nuclear power plants, energy demand, and the flexibility of energy infrastructure for a real case study (Finland). We propose wind-nuclear compromise charts to envision the impact of any mix of these two technologies on four parameters: total costs, power exchange, carbon emissions, and renewable energy integration. The results suggest that nuclear power constrains the room for maximum uptake of wind energy by a descending parabolic relationship. If nuclear power production exceeds 50% of the total power demand, wind will be unlikely to penetrate in shares over 15% of the respective demand. Moreover, we investigate the role of four flexibility options: demand side management, electrical energy storage, smart electric heating, and large-scale heat pumps (backed with thermal energy storage). Heat pumps (which are in connection with combined heat and power (CHP) and district heating systems) offer the highest efficiency in balancing excess power from variable RES. However, power-to-heat options offer a limited capability for absorbing excess power, as oversupply arises mainly in the periods with relatively low demand for heat. This calls for longer-term energy storage and/or other flexibility options to achieve the planned targets in wind-nuclear scenarios.

The study concerns the ramp rate problem that is associated with the large-scale integration of wind power. As planned 3GW wind farms are built in Taiwan, the potential variability of the net load must be estimated to determine the flexibility requirement. This work will use numerical weather predictions in Taiwan to estimate total power output from 3 GW wind farms, and analyze the ramping characteristics of the net load using statistical approaches. Its results can provide the operators of Taiwan's power generation system an important reference for determining the required ramping capability in the future. [ABSTRACT FROM AUTHOR]

Towards low-carbon energy systems, there are countries with ongoing plans for expanding their nuclear power capacity, and simultaneously advancing the role of variable renewable energy sources (RES), namely wind and solar energy. This crossroads of capital-intensive, baseload power production and uncontrollable, intermittent RES may entail new challenges in the optimal and economic operation of power systems. This study examines this case by hourly analysis of a national-level energy system with the EnergyPLAN modeling tool, coupled with wind integration simulations (including uncertainty) implemented using MATLAB. We evaluate the maximum feasible wind integration under different scenarios for nuclear power plants, energy demand, and the flexibility of energy infrastructure for a real case study (Finland). We propose wind-nuclear compromise charts to envision the impact of any mix of these two technologies on four parameters: total costs, power exchange, carbon emissions, and renewable energy integration. The results suggest that nuclear power constrains the room for maximum uptake of wind energy by a descending parabolic relationship. If nuclear power production exceeds 50% of the total power demand, wind will be unlikely to penetrate in shares over 15% of the respective demand. Moreover, we investigate the role of four flexibility options: demand side management, electrical energy storage, smart electric heating, and large-scale heat pumps (backed with thermal energy storage). Heat pumps (which are in connection with combined heat and power (CHP) and district heating systems) offer the highest efficiency in balancing excess power from variable RES. However, power-to-heat options offer a limited capability for absorbing high-level excess power, as oversupply arises mainly in the periods with relatively low demand for heat. This calls for longer-term energy storage and/or other flexibility options to achieve the planned targets in wind-nuclear scenarios. [ABSTRACT FROM AUTHOR]