Quantitative study on role of flexibility index of coal-fired power units in regulating wind and solar power generation

Within the swift progression of renewable energy, particularly wind and solar power, enhancing the regulatory capacity of supporting power sources is crucial. This serves as a vital assurance for the development of new power systems. A significant approach in this regard involves fully harnessing the flexibility potential of coal-fired power units. Currently, there is a growing demand for enhanced flexibility indicators in coal-fired power units, including the minimum operating load, load change rate, and start-up time. However, methodologies for quantitatively analyzing their regulatory impact on wind and solar power generation remain under developed. To address this issue, a computational model is developed for the peak shaving capacity of coal-fired power units. This model is constructed via the Python language and considers both the temporal production characteristics of wind and solar energy as well as power balance. Additionally, the operational characteristics of coal-fired power units are examined at minute-level time intervals. This analysis is conducted using the actual wind and solar power generation curves of a region in Inner Mongolia as a case study. The investigation focuses on the impact of varying minimum operating loads, load change rates and start-up times on the operating characteristics of these units. The findings suggest that, given the wind and solar power installations and resources in this region, as the minimum operating load of coal-fired power units decreases, the incremental rise in wind and solar power consumption with the unit’s minimum operating load change range (10%) progressively diminishes. Nevertheless, when the minimum operating load decreases from 30% to 20%, the enhanced wind and solar power consumption can still account for 4.88% of the total annual wind and solar power generation in this region. The enhancement of the damping effect on system load fluctuations can be achieved by increasing the load change rate of coal-fired power units. Specifically, when the load change rate reaches 6% Pe/min, it results in a reduction of the annual average change rate of the total system load by 35%, compared to scenario where there is no coal power involvement. As the start-up time for coal-fired power units decreases, the proportion of wind and solar power consumed during the change interval of 1 h increases. Furthermore, the likelihood of a single day witnessing both unit start-ups and shutdowns increases from 15.9% to 60.4% when the start-up time decreases from 4 h to 1 h.