Design of Control Logics for Islanding Schemes in Thermal Power Plants

Abstract: This paper focuses on the design of control logics for islanding schemes for three thermal power stations in Rajasthan, India. Islanding occurs when a power plant is isolated from the main utility grid, and this research seeks to design an algorithm for control logics for islanding schemes, develop a load-shedding scheme to stabilize the power system, and investigate planned islanding on rural feeders with multiple distributed generation units. The paper begins by defining islanding and its importance in ensuring uninterrupted power supply during grid disturbances. The research reviews various techniques used for the detection and classification of islanding events, including deep learning, wavelet transform, and fuzzy logic, highlighting the significant research activity in this area. The proposed control logics are based on the concept of decreasing frequency due to heavy load and low generation, and at a pre-determined frequency, boundary transmission lines will trip, and local loads will be fed from the local generator. Under-frequency relays are used to sense major grid disturbances and initiate load scheduling prior to islanding. The design of islanding schemes and load flow studies are also discussed to find balance between loads and generation. The research shows that islanding can offer advantages such as uninterrupted power supply in the island during grid disturbances and easier restoration of the island compared to the whole system from a blackout. Therefore, the development of effective islanding control logics is crucial for ensuring reliable and stable power supply. This study presents a comprehensive study of the design of control logics for islanding schemes for thermal power stations in Rajasthan. The proposed algorithm and load-shedding scheme provide a practical approach for ensuring stable power supply during grid disturbances, while the investigation of planned islanding on rural feeders with multiple distributed generation units offers valuable insights into the feasibility of implementing such schemes in similar contexts