چكيده لاتين
The occurrence of initial events in the system can cause cascading outages in power system and this, in turn, triggers instability. Consequently, the system operator must be consistently able to accurately assess the operational state of the system and to determine its proximity to instability. One of the most critical events in power system is voltage instability. When using voltage drop and voltage stability indices to determine the operating state of the system, it is possible to mistakenly identify that the system is in a normal condition. In such circumstances, if an increase in load occurs, there may be only a short time remaining until instability. In this situation, there is a high chance that the operator cannot maintain the network stability. This can easily happen because the remaining time until instability has not been considered when evaluating the systemʹs operating state. Therefore, the remaining time until instability should be treated as a critical factor to accurately determine the operating state of the system. In addition, when the system is in critical conditions, control measures must be implemented to ensure system stability. The system operator has various available tools and options to achieve this goal. However, these control actions must be adapted during the remaining time until instability occurs. If the remaining time until instability is very short, the system operator should implement some control measures quickly, such as load shedding. Thus, in addition to assess the operating state of the system, the remaining time until instability is a fundamental and determining factor to select appropriate control actions. This important issue has not been previously considered in the assessment and control of power systems. Thus, the aim of this thesis is to control power system by considering the remaining time until instability occurs. In doing so, a method has been developed to estimate this remaining time. By accurately determining the time left until instability, along with utilizing voltage drop and voltage stability indices, we will be able to effectively evaluate the operating state of the system. Once the operating state is identified, it will be necessary to implement preventive or corrective control measures. To achieve this, this thesis proposes two algorithms for coordinating preventive and corrective control actions while considering the remaining time until instability. After the selection of either preventive or corrective control measures, we need appropriate models for their implementation. Therefore, this thesis introduces two models based on VSC-OPF to execute preventive and corrective controls. These models incorporate the remaining time until instability into the constraints of the problem, allowing the system operator to be assured that there is a relatively substantial amount of time until instability may occur. To assess the effectiveness of the proposed algorithms and models, simulations are carried out on the IEEE 14-Bus and IEEE 57-Bus networks.
