How to ensure efficient and stable power grid operation  

The growing adoption of renewable energy sources such as solar and wind energy is transforming our power systems, highlighting the need for technologies that ensure efficient frequency support. In conventional power generation, inertia plays a crucial role as it allows generators and other components to maintain stable operating frequencies in case of severe system contingencies. However, as power grids become increasingly reliant on inverter-based renewable sources, this inertia support becomes less reliable, raising challenges for the future of energy stability. 

A research team from the Advanced Power and Energy Center (APEC) at Khalifa University has designed an online tool for assessing, predicting and enhancing the frequency stability of power systems that rely on renewable energy sources and energy storage systems. This frequency stability prediction and enhancement (FSP&E) tool works alongside a reserve-power allocation strategy to probe the real-time frequency response of the power system in a virtual environment.   

“The combination of these strategies can be employed by the transmission system operator – to maintain frequency stability in the presence of significant renewable energy integration, reduced system inertia and unexpected disturbances such as the sudden tripping of the largest generator or major transmission lines,” says Mohamed El Moursi, one of the co-authors of the study. 

“The FSP&E tool incorporates several critical features that are applicable to power grids.” 

Mohamed El Moursi

The FSP&E tool estimates the frequency response of the entire power system in different situations and at various levels of inertia. It also calculates the optimal amount of reserve power required to maintain the frequency above the minimum value needed for stable operation.  

“The FSP&E tool incorporates several novel features that are applicable to power grids,” says El Moursi. First, the tool calculates the system inertia in real-time and investigates the resilience of the power grid to sudden events. Next, it assesses the frequency response during these events. Finally, the tool estimates the required reserve power to maintain frequency stability and dynamically adjusts the hybrid renewable power-plant controller accordingly.  

“Subsequently, the energy management system of the power grid can use the reserve power allocation in the photovoltaic power plants and battery energy storage systems with the load shedding approach, for extreme cases, to save the power grid in response to severe system disturbances,” El Moursi explains. 

Continuous feedback from the FSP&E tool to the transmission system operator on system performance can help ensure the power system operates within its permissible frequency limits, even with the high intermittence of renewable power generation. This improves the reliability of the FSP&E tool in ensuring frequency stability in low-inertia and high-renewable power grids. 

The research team’s next step is to investigate the intermittent nature of photovoltaic power generation. “The impact of frequency-dependent loads on the estimation of frequency nadir [the lowest frequency point in response to system disturbance] and reserve power will also be probed,” says El Moursi.  

Reference  

Sattar, F., Ghosh, S., Isbeih, YJ., El Moursi, MS. Al Durra, A., El Fouly, THM. A predictive tool for power system operators to ensure frequency stability for power grids with renewable energy integration. Appl. Energy 353, 122226, (2024). | Article