Topology control algorithms in power systems

This research focuses on improving the efficiency of power market operations by providing system operators additional tools for managing the costs of supplying and delivering electricity. A transmission topology control (TC) framework for production cost reduction based on a shift factor (SF) representation of branch and breaker flows is proposed. The framework models topology changes endogenously while maintaining linearity in the overall Mixed Integer Linear Programming (MILP) formulation. This work develops the DC lossless, and loss-adjusted TC formulations that can be used in a Day Ahead or intra-day market framework as well as an AC-based model that can be used in operational settings. Practical implementation choices for the Shift Factor formulation are discussed as well as the locational marginal prices (LMPs) under the TC MIP setting and their relation to LMPs without TC. Compared to the standard B-theta alternative used so far in TC research, the shift factor framework has significant computational complexity advantages, particularly when a tractably small switchable set is optimized under a representative set of contingency constraints. These claims are supported and elaborated by numerical results

Decentralized operation and control of integrated transactive and physical grids

The objective of this research is to develop a decentralized grid architecture to manage the physical and transactive aspects of power systems. With exponentially decreasing prices of PV the adoption of volatile and non-dispatchable sources into the grid has increased. This has two key impacts. Physical phenomenon like congestion of power flow corridors and voltage volatility become more prevalent. Similarly, with increasing prosumers, a multi-agent system is created, with each asset owner wanting to transact power. Existing transactive and physical control solutions are centralized, rely on low-latency communications, often require detailed knowledge of network topologies and are often highly coupled. The proposed research showcases fast localized grid control solutions in the form of hybrid transformers to manage physical phenomenon like congestion and voltage volatility. Furthermore, a decentralized, communication-free and topology-agnostic real-time pricing mechanism is proposed to enable collective stabilization even under wide variations in available generation. Thus, an architecture is presented where the transactive and physical grid constraints are handled in a decoupled fashion while being integrated through the physics of the network.Ph.D

Yellow Head Virus: Transmission and Genome Analyses

Yellow head virus (YHV) is an important pathogen to shrimp aquaculture. Among 13 species of naturally YHV-negative crustaceans in the Mississippi coastal area, the daggerblade grass shrimp, Palaemonetes pugio, and the blue crab, Callinectes sapidus, were tested for potential reservoir and carrier hosts of YHV using PCR and real time PCR. The YHV replicated in the daggerblade grass shrimp, and was still detectable on 36 d post-inoculation, causing 8% mortality after injection. However, YHV did not replicate in the blue crab. These data suggest that the daggerblade grass shrimp could act as a reservoir host for YHV. Storage conditions of hemolymph samples containing YHV may result in a decline of virus or exhibit false-negative results in viral detection. The YHV-positive hemolymph was stored at either 4 or 25 °C for a 6-d period, the viral load number at 4 °C was not significantly different from that stored at 25 °C. The only difference was between the samples stored for 6-d at either 4 or 25 °C and those stored at -80 °C, suggesting that shrimp hemolymph can be stored at either 4 or 25 °C for 3-5 d without a significant reduction in measured YHV RNA levels. The whole genome of 3 isolates in Penaeus monodon obtained from Thailand in 1992, 1995, and 1999 was sequenced. The only indel event in the coding region was located in the 5\u27 end of ORFla, containing a segment of 12 nt. Other indels occurred in the non-coding region. The 3\u27 untranslated region (UTR) forms a putative pseudoknot with an octonucleotide motif being the counterpart in the 3\u27 UTR of Coronavims. The phytogeny of Nidovirales was reconstructed based on 48 nidovirus proteome sequences, demonstrating a consistency with the contemporary phytogeny. Recombination in RNA viruses plays a major role in virus diversity and evolution. Seven recombination events were detected among the 4 YHV genomes with high statistical support. The divergence times for the most recent common ancestor of the YHV lineage were dated back to 1970-1980s based on 3 recombination-free data sets. These values were consistent with shrimp culture practice in Asia

Hierarchical congestion management for a deregulated power industry

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (p. 205-216).by Chien-Ning Yu.Ph.D

RSV sequence variation and within-host minority variant dynamics

Respiratory syncytial virus (RSV) infection is a common disease that causes the most severe disease in the extremes of age. Parts of the RSV genome are extremely variable, however, origination of genomic variation of RSV is not studied very well. Epidemiology studies have shown rapidly changing RSV strains and grouped these in genotypes based on a part of the RSV genome that consists of the (partial) G gene. In this thesis, the genotyping system was inspected and it showed that the part of the G gene previously used for genotyping did not contain enough information to reliably determine which genotype a strain belonged to. Phylogenetic analysis was performed to determine the necessary and sufficient part of the genome to determine the genotype reliably, which was full G. Other proteins were investigated for variability as well and both F and L carried plenty of variation as well. The amount of variation within a patient has been understudied. Therefore, a new method was optimised to detect the prevalence of minority variations in clinical samples. The prevalence of minority variants was examined in a community cohort and hospital cohort from season 2015-2016 of which all samples were spatiotemporally and age-matched. The detected genotypes were GA2 and ON1. Most clinical samples in this study did carry minority variants, however, there was no difference in the amount of variation between community and hospital samples. The gene that displayed the most variations per nucleotide, and most non-synonymous variations was G. This research also demonstrates that these variations can be transmitted or develop during acute infection. Consecutive samples from volunteers inoculated with a known RSV strain showed that both synonymous and non-synonymous variations can occur and their frequency can increase, decrease or remain stable over time. The F gene rarely developed non-synonymous variations in this study.Open Acces