Conceptualization, design and optimal operation of hybrid AC-DC power router grids
(English) Driven by increasingly strict climate goals, the need for modernization of the electric power system has intensified in recent years. The transition towards a distributed and decarbonized smart energy system requires modernizing power grids to accommodate the widespread adoption of renewab...
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| Tipo de documento: | tese |
| Estado: | Versão publicada |
| Data de publicação: | 2025 |
| País: | España |
| Recursos: | CBUC, CESCA |
| Repositório: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/695075 |
| Acesso em linha: | http://hdl.handle.net/10803/695075 https://dx.doi.org/10.5821/dissertation-2117-439793 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Optimal power flow Power router Energy router Distribution grid Modelling Smart grid Second-order cone Pyomo Python Branch-flow model Converter losses Modular-Multilevel Converter Power router grid Àrees temàtiques de la UPC::Enginyeria elèctrica 621.3 - Enginyeria elèctrica. Electrotècnia. Telecomunicacions |
| Resumo: | (English) Driven by increasingly strict climate goals, the need for modernization of the electric power system has intensified in recent years. The transition towards a distributed and decarbonized smart energy system requires modernizing power grids to accommodate the widespread adoption of renewable energy sources (RES), electric vehicles (EVs), and distributed energy resources (DERs). One key factor to enable this is the advancements in power electronics and their widespread deployment. The Power Router (PR) technology is crucial for this transition, as it facilitates flexible and efficient management of electricity as well as integration between AC and DC grids. It is a device composed of multiple ports that provides a seamless interface of different elements of a power grid by controlling the power between ports. In the first half of this thesis, different kinds of PR concepts are investigated and a novel grid concept based on PRs has been defined, named Power Router Grid (PRG). The PR concept adopted consists of coupling a set of voltage source converters to a common DC bus, in which each converter functions as a different input or output port. The converter model design used is the Modular-Multilevel-Converter (MMC) and is adaptable for PRs with any number of ports and any power level. Then, the theory behind the PRG is presented. First, a set of rules is proposed to ensure the correct configuration and operation of the PRG. Secondly, each PR role is defined based on their tasks within the PRG. Finally, in combination with graph theory methods, a new concept is introduced called Slack Tree (ST). The ST is the backbone that regulates and ensures power balance and the feasibility of the PRG operation, and is a connection path between all ports operating as a slack element. In the second half, all of these novelty concepts behind the PRG are combined with optimal power flow (OPF) models, convexity techniques and converter loss modelling. The goal is to create a Python-based convex OPF formulation suitable for any hybrid AC-DC network Based on PRs. The mathematical formulation is based on a second-order cone relaxation of the traditional power flows equations applied to radial networks. The developed PRG-OPF however, due to the decoupling characteristics of the PRs, is demonstrated to be suitable for any network meshed through PRs. In the last part of thesis, this formulation is further expanded to include the effects of converter losses. The loss model developed is defined as a set of linear constraints that are scalable and easy to implement inside an OPF. Additionally, other constraints regarding DC lines and AC grid integration are developed and integrated. The proposed OPF formulation is loss-aware and utilizes the full potential of PRs to integrate different systems. Throughout this doctoral thesis, seven case studies are presented in order to demonstrate the validity of the proposed concepts. Specifically, the power flow analysis show the viability of the highly-flexible PRG design. Different sensitivity analysis are conducted in order to assess the impact of converter losses and also the ST selection in the optimal operation of the PRG. Among the key remarks, the results demonstrate that the choice of ST does not significantly affect line losses. It is also shown that, despite the added converter losses, the PRG is more efficient than a traditional network in most scenarios, particularly in the presence of loads with low power factor. |
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