In the dynamic world of renewable energy transmission, the integration of intermittent sources like wind and solar power poses significant challenges to the stability and safety of power grids. A groundbreaking study led by Maolan Peng from the Electric Power Research Institute, CSG EHV Power Transmission Company, Guangzhou, China, published in the journal ‘Frontiers in Electronics’ (translated to ‘Frontiers in Electronics’) offers a promising solution to these challenges. The research focuses on enhancing the control strategies for Line Commutated Converter based High Voltage Direct Current (LCC-HVDC) transmission systems, which are pivotal in transmitting large amounts of power over long distances with high efficiency.
The study delves into the complex operating conditions that renewable energy sources (RESs) introduce into the AC power grid. Peng explains, “The power intermittency and fluctuation of renewable energy sources create variable operating conditions that a single converter control strategy cannot adapt to effectively.” This variability can lead to instability and safety concerns in the power system. To address this, Peng and his team developed a flexible control switching method designed to adapt to different operating conditions seamlessly.
The researchers first established a state-space model of the LCC-HVDC system with renewable energy at the sending-end. This model allowed them to analyze the small-signal stability and stable operating range of the system under various control strategies. Based on this analysis, they designed control switching principles that enable smooth transitions between different control strategies with minimal disturbance to the system.
One of the key innovations of this research is the ability to switch between constant power control and constant current control strategies. This flexibility ensures that the LCC-HVDC system can maintain stability and efficiency regardless of the fluctuating power output from renewable sources. Peng highlights, “Our method not only enhances the stability of the system but also ensures a smooth switching between different control strategies with minimal disturbance to the system.”
To validate their approach, the team built a simulation model on the PSCAD/EMTDC platform. The simulation results demonstrated that the disturbance during control switching was relatively small, confirming the feasibility and effectiveness of the flexible control switching method. This breakthrough has significant commercial implications for the energy sector. As the integration of renewable energy sources continues to grow, the ability to maintain stable and efficient power transmission will be crucial. Peng’s research provides a robust solution that can be implemented in real-world scenarios, paving the way for more reliable and efficient LCC-HVDC systems.
The implications of this research extend beyond immediate applications. As the energy sector continues to evolve, the need for adaptive and resilient control strategies will become even more critical. Peng’s work sets a precedent for future developments in the field, encouraging further innovation in control strategies for HVDC systems. By addressing the challenges posed by renewable energy sources, this research contributes to the broader goal of creating a more sustainable and stable energy infrastructure.
