Power system intentional islanding for different contingency scenarios using discrete optimization technique

• Main Author: Nur Zawani Binti Saharuddin
• Format: text::Thesis
• Language: English
• Published: 2023
• Subjects: POWER SYSTEM INTENTIONAL ISLANDING

Power systems are susceptible to unavoidable failures or outages. One of these incidents is critical line outage, which can lead to the occurrence of severe cascading failures. These cascading failures can cause the system to split in an uncontrollable manner, forming unbalanced islands, which results in severe instability problems before the system completely collapses. Intentional islanding is one of the remedial actions that can be implemented to prevent severe cascading failures following a critical line outage. This approach splits the system to form balanced, stand-alone islands in order to continuously supply electricity to the consumers until the system is completely restored. However, an optimal intentional islanding strategy is required for this purpose. Hence, this thesis proposed a Modified Discrete Evolutionary Programming (MDEP) to determine the optimal intentional islanding strategies for different large-scale power systems following a critical line outage. First, N-1 contingency analysis was performed to identify the critical line outages. Next, graph theory was used to map the network, where the physical connections of the network were represented by edges and vertices. The initial intentional islanding solution was determined using graph theory approach, to facilitate the proposed MDEP algorithm in determining the optimal intentional islanding strategy. Once the optimal solution was obtained, the power balance for each island was checked to ensure that the loadgeneration balance criterion was met. If there was power imbalance in a particular island, the MDEP-based load shedding scheme developed in this research was executed for that island. Finally, the bus voltage was checked and transmission line power flow analysis was performed to ensure that the solution did not violate the allowable voltage and transmission line capacity limits. The performance of the proposed MDEP algorithm was evaluated using the IEEE 30-bus, IEEE 39-bus, and IEEE 118-bus test systems. The results showed that the MDEP algorithm was capable of determining the optimal intentional islanding strategy (without critical line outage) with a lower total power flow disruption compared to those of other published works. In addition, the results of the case studies (with critical line outage) showed that the MDEP algorithm was able to obtain the optimal intentional islanding strategy with minimal power flow disruption.