Impact of Grid-Following and Grid-Forming DERs on Resilient Operation of Holonic Grid

This thesis investigates how different distributed energy resources (DERs) impact the resilience operation of a holonic grid. The holonic grid consists of two or more connected microgrids and /or provisional microgrids (PMGs). The type of the DER, i.e., grid-forming or grid-following, affects the operations of the holonic grid, particularly during the islanded mode. To study this emerging and timely topic, a resilience-oriented holonic grid optimal operation model is proposed. This model carefully formulates the operations of both grid-forming and grid-following DERs. A variable value of lost load (VoLL) is further employed in the proposed model to help quantify and monetize the potential load curtailments, and accordingly, observe the holonic grid operation in response to various extreme external events. To evaluate the proposed model, two cases and multiple scenarios are performed on a sample holonic grid. The studied cases analyze the impact of microgrids energy exchange within the holonic grid, and scenarios take into account various resilience operations

Optimal Operation of Integrated Microgrids

Microgrids\u27 deployments are increasing and projected to increase even more in future due to the significant advantages that are provided by this technology for end-use customers. However, microgrids can be connected to each other to create integrated microgrids system, which can further promote the anticipated and desired benefits. An integrated operation of microgrids can potentially improve the local power system reliability and resilience, increase the individual microgrids\u27 economic benefits, and promote further utilization of renewable energy resources. Integrating microgrids, to achieve a microgrid network or cluster, is expected be an essential application towards smarter power grids and a key operational feature in emerging modern distribution grids. Consequently, finding the optimal schedule of the integrated microgrids during the grid-connected and islanded operation modes is necessary to achieve the most possible economic and environmental benefits. In this dissertation, the integrated microgrids systems\u27 operation is investigated, researched and studied. The impact of elevating prosumers to provisional microgrids (to form an integrated microgrids system) is discussed and examined, and further independent and integrated microgrid optimal scheduling models are developed and mathematically simulated, to identify its merits and importance in the distribution grid. In addition, the value/quantity of the unused capacities in the microgrids is discussed and investigated, and a communicative optimal scheduling model for integrated microgrids systems is developed and proposed, in which the local power exchange between the integrated microgrids is determined through an iterative exchange of relevant information based on unused capacity and unmet power in the microgrids. Moreover, the microgrids\u27 privacy is taken into consideration by a developed optimal scheduling model based on the Lagrange Relaxation (LR) method, where the optimal scheduling problem is decomposed into individual optimal scheduling problems using the LR to take prevailing privacy issues into account. Furthermore, an optimal scheduling model for integrated microgrids systems in holonic distribution grids is developed, where the proposed model is capable of determining the optimal network topology, i.e., optimal connections among the integrated microgrids, to ensure minimum microgrid-specific and system-wide operation cost as well as maximum reliability of the entire integrated system. It should be mentioned that all proposed models are mathematically formulated using mixed-integer programming, and studied through numerical simulations to show their performance and effectiveness