Transient stability analysis is performed to assess the power system's condition after a severe contingency and is carried out using simulations. To adequately assess the system's transient stability, the correct dynamic models for the machines (i.e., generators, condensers, and motors) along with their dynamic parameters must be defined. The IEEE test systems contain the data required for steady-state studies. However, neither the dynamic model of the machines nor their specific parameters have been established for transient studies. As a result, there is a demand for test bed systems suitable for transient analysis. This paper defines dynamic machine models along with their parameters for each IEEE test bed system, thus producing full dynamic models for all test systems. It is important to mention that the parameters of the proposed dynamic models are based on typical data. The test systems are subjected to large disturbances, and a case study for each test system, which examines the frequency, angle, and voltage stability, is presented. Furthermore, the proposed dynamic IEEE test systems, implemented in PowerWorld, are available online.

Intentional Controlled Islanding (ICI) has been proposed as a corrective measure of last resort to split the power system into several sustainable islands and prevent cascading outages. This paper proposes a novel ICI algorithm based on a linear programming (LP) formulation that directly determines an islanding solution with minimal power-flow disruption for any given number of islands, while ensuring that each island contains only coherent generators. In addition, the proposed algorithm enables operators to constrain any transmission line to be excluded from the solution, allows the control of the size of islands and ensures their connectivity. The basis of the proposed LP formulation is an exact mixed integer linear programming (MILP) formulation. A search space reduction procedure that generates additional constraints for reducing the search space of the MILP is also proposed. In most cases, these additional constraints are enough for the relaxed MILP formulation (LP formulation) to generate optimal solutions. Nonetheless, the proposed LP formulation is executed as a part of a recursive linearization procedure, which ensures that optimal solutions are always obtained. Multiple simulation results demonstrate the ability of the proposed LP ICI algorithm to meet the requirement of real-time controlled islanding in large-scale power systems.

Power system operators are facing major challenges today to keep the system operating at the admissible limits. Recent blackouts demonstrated the need for a systematic study and design of a comprehensive system control strategy. Intentional Controlled Islanding (ICI) has been proposed as an effective corrective control action of final resort to save the system from a partial or a complete blackout. ICI limits the occurrence and consequences of blackouts by splitting the power system into a group of smaller, stable, and sustainable subsystems, also called islands. After a controlled system separation, power system operators should resynchronize and reconnect each island to restore the system. In this sense, real-time knowledge of the operating condition of the islands is required. In this paper, a real-time ICI and restoration scheme is proposed. The proposed scheme consists of an ICI algorithm that finds islanding solutions with minimal power-flow disruption while considering power system restoration constraints (e.g., blackstart availability, sufficient generation capacity and observability), a real-time state estimator that monitors the system before and after the islanding, and a restoration process. The proposed ICI and restoration scheme is tested using the dynamic IEEE 39- and 118-bus test systems.

Power systems are prone to cascading outages leading to large-area blackouts, and intentional controlled islanding (ICI) can mitigate these catastrophic events by splitting the system into sustainable islands. ICI schemes are used as the last resort to prevent cascading events; thus, it is critical to evaluate the corresponding system risks to ensure their correct operation. This paper proposes a unified framework to assess the risk of ICI schemes. First, a novel ICI method to create islands with minimum power imbalance is presented. Further, a risk assessment methodology is used to assess the probability and impact of the main operational modes of the ICI scheme. The unified framework provides insights on the benefits of implementing ICI, considering the uncertainties related to its reliability. The ICI scheme is demonstrated using the IEEE 9-bus system. The proposed unified framework is then fully deployed on the actual power system of Cyprus. Multiple case studies on the real network are created to demonstrate the adaptability and robustness of the proposed scheme to different system conditions. The adoption of the unified framework highlights that the system risk significantly reduces with the ICI in service, even when the reliability uncertainties associated with the scheme are considered.

Cascading outages leading to large-area blackouts can be mitigated using intentional controlled islanding (ICI). An ICI scheme must define the most suitable time to split the system after a severe contingency (i.e., when to island), as well as to quickly determine the set of branches to be disconnected to create stable islands (i.e., where to island). Most of the works in the literature, however, focus on the latter and little has been done to address the “when to island” problem. To fill this gap, this paper proposes a unified methodology to determine the most suitable moment for islanding. First, the proposed methodology uses real-time information to estimate the rotor angles of generators, which, in turn, serve to define the suitable number of coherent generators and the actual coherent groups. It then adopts the concept of area-based center of inertia-referred rotor angle index to determine the actual time of islanding. The unified methodology for determining the number of islands to be created, the coherent generators, and the time for islanding is tested using the IEEE 39- and 118-bus test systems. Multiple case studies are presented to demonstrate the adaptability and effectiveness of the proposed unified methodology to different system conditions.

The Fault Ride Through (FRT) capability of renewable energy sources (RES) for providing support to the power grid under several disturbances allows us to consider them not only as passive elements in the power system network, but also as ancillary services for the mitigation of evolving contingencies. In this paper, an investigation of the FRT operation of RES according to current grid regulations highlights some impacts on the system response that were not considered previously and require to be addressed. Slight modifications of the current grid codes are therefore necessary to solve these problems. A critical dead band zone modification for smother fault recovery is suggested. Moreover, this paper proposes the use of an adjustable parameter into the FRT strategy for a fair compromise of voltage and frequency support. The proposed FRT strategies are applied to a RES that is interconnected with the IEEE 14-bus test system and dynamic electromagnetic transient simulation results are provided.