Assessing Techno-Economic Performance of Synchronous Condensers and Static Synchronous Compensators in Renewable Energy-Integrated Weak-Grids Using Hedge Feedforward Feedback-Based Online Gated Recurrent Unit

To achieve net-zero targets in many counties, renewable energy generators (REGs) are integrated with grids where less fault current is produced compared to synchronous generators. Accordingly, fault level availability, known as ‘system strength’, is reduced at point of coupling (POC) buses. A minimum system strength level is crucial for REGs to accurately detect and ride-through faults. To maintain adequate system strength in renewable energy-based weak grids, researchers and engineers have recommended supplementary devices, such as synchronous condensers (SynCons) or static synchronous compensators (STATCOMs), to provide the required fault-current. Because SynCons and STATCOMs are costly devices, their optimal sizes and placement were investigated in existing literature. However, no long-term techno-economic analysis was conducted to confirm appropriate selection between SynCons and STATCOMs. To address the research gap, this paper investigates the long-term financial feasibility of SynCons and STATCOMs by considering their optimal allocation and sizes. A hedge feedforward feedback-based online gated recurrent unit (HFF-OLGRU) optimisation learning algorithm is developed and compared with existing learning approaches in order to determine the best solution. The technical and economic findings suggest that SynCons improve voltage recovery time approximately 0.06 s and achieve net profit USD$42.68M over STATCOMs in renewable energy-based weak grids.