The current energy systems with the mix of renewable and conventional sources are already working on their maximum capacity in order to meet the existing demand. In the near future to meet the burgeoning demand, the future electrical power system would be a mix of both AC and DC systems coexisting with each other. With the fast paced development of smart grids, decentralised system and micro grids, there is an increasing interest in the LVDC (Low Voltage Direct Current) distribution. Also there is increase in the loads in the residential and commercial sector side that require DC supply inherently. To tap in and realise the potential of the LVDC distribution systems, it requires the appropriate infrastructures to be developed that supports its assimilation faster. This thesis “The Design and development of LVDC cable” is a step forward in realising the potential that DC has in the LV distribution side. This research is done in collaboration between TU Delft and the Prysmian Group.

To begin with, two LVDC statespace based dynamic distribution system model namely: a neighbourhood distribution system and a ship distribution system are formed. The LVDC cables are incorporated as lines into these models. The sensitivity and stability analyses are performed by varying each of the active parameters individually, the influence that each of the active parameter has on node voltages, line currents and the stability of the system are studied and the trend is absorbed through this analysis. This analysis is set to be performed in both distribution systems under monopolar and bipolar configuration.

Subsequently, the short circuit analysis i.e the pole to pole and pole to neutral fault analysis is also performed on both the neighbourhood and ship distribution system. Here the cable’s active parameters that are expected to have an influence on the system performance and the line current during short circuit are taken into consideration. These active parameters are varied throughout this analysis and the resulting plots are further analysed to study their influence. These active parameters are cable resistance, cable inductance, cable capacitance, and cable length. The observations are tabulated for each of the active parameters individually. The generated results from this study would support in better assessment of cable’s active parameters influence on the short circuit current and designing the LVDC cables.

The accuracy of the dynamic model are validated by breaking the distribution system model into smaller sections and forthcoming results are compared to get the model accuracy. Finally based on the results from the sensitivity stability and short circuit analyses the optimal characteristics of the LVDC cables is formulated.

The growing global energy demand and correlated rise in carbon emissions is forcing us to increase the use of renewable sources. The residential sector represents a large part of the total energy consumption, and European governments are investing in distributed PV to increase the renewable share in this sector. However, on top of the solar power variability, residential systems are also characterized by very unstable load profiles. This issue can be solved by incorporating energy storage, that has many technical and economic benefits for the prosumer, especially if a long-term seasonal storage technology is used. Among all the available storage types, after an extensive literature study, some developing technologies proved to be suitable for this purpose: redox flow batteries (all-vanadium, hydrogen-bromide, zinc-bromide) and hydrogen systems.

For this work, a model was built in MATLAB Simulink to study and reproduce the behaviour of these storage systems in a grid-connected residential environment, and an optimization was set up to find the optimal sizing of the components and investigate the economic feasibility of the whole system. The models results proved that in the present scenario, storage integration is still too expensive with these technologies. However, future projections with different incentive scenarios demonstrate the potential of vanadium and zinc-bromine batteries, and highlight a dramatic cost reduction for hydrogen systems.

Advancements in the field of Information and Communication Technologies (ICT) has enabled the possibility to utilize the flexibility offered by responsive assets in a better way by employing Demand Response (DR) schemes. This thesis analyzes the performance of one such DR scheme developed at TU Delft called Forecast mediated Market Based Control (F-MBC), which aims to coordinate such flexible assets by communicating "self-fulfilling forecasts" [1]. The main aim of the project is to investigate the applicability of this method in real-world settings. To do so, several simulation scenarios were formulated to understand how well F-MBC coordinates heterogeneous populations of uninterruptible time shiftable loads over an extended time horizon, both from the system perspective and devices' perspective. The thesis also proposes an approach to test the mechanism in a rolling horizon setup. First, the performance of F-MBC is examined under several combinations of deferrable loads having identical deadlines. Then, its ability to coordinate devices with dynamic load profiles under a complex realistic setting is investigated. Trade-offs adopted when simulating such a setup is also highlighted. Results indicate that while F-MBC achieves good overall performance when coordinating devices with uniform power consumption profiles, its performance in scheduling heterogeneous populations of devices with dynamic load profiles was quite variable. When devices that consume high power when they start was considered for coordination, F-MBC was able found to allocate the devices in such a manner that steered towards overall cost minimization. However, its performance if used to schedule devices which consume low power when it starts was found to be undesirable. Hence, several recommendations were provided to deduce better conclusions about the applicability of the mechanism in reality. References: [1]Hazem A. Abdelghany, Simon H. Tindemans, Mathijs M. de Weerdt, Han la Poutré, Distributed coordination of deferrable loads: A real-time market with self-fulfilling forecasts, Sustainable Energy, Grids and Networks, Volume 23, 2020, 100364, ISSN 2352-4677. http://www.sciencedirect.com/science/article/pii/S2352467720302952

Technical developments in generation and demand of energy will motivate significant change in the electric power grid, both on the transmission and the distribution level. A major innovation would be the successful transformation of the current passive power grid towards an active and ICT-based smart grid. Among the technical efforts that will help to pursue this goal, the renewed interest in DC (direct current) distribution and transmission applications is playing an important role. In particular, the interest in the DC universal distribution networks is renewed since most of the renewable energy generation technologies (e.g. PV modules, fuel cells) and loads (e.g. LED lighting, electric vehicles) are DC-native. Their direct connection would allow to skip conversion steps, thus providing higher efficiency.

The focus of this thesis lies on the steady-state power flow analysis, a numerical study used in electrical engineering to assess the flows of power in the network. The aim of the thesis is to review the state of the art in computational methods for AC and DC power flow analysis and to determine a suitable method to develop a power flow tool for the DC framework.

The literature study revealed that most algorithms aim to solve the non-linear power flow problem without taking into account characteristics typical of future DC networks, such as highly meshed topologies and constant power converters. An innovative power flow method has there- fore been developed in order to include different node behaviours, such as constant voltage, constant current, constant impedance, constant power and I-V droop control. A case study based on the IEEE European Low-Voltage Test Feeder is analysed to provide an example of the application of the power flow tool.

The thesis shows that it is possible to linearize the system equations considering the constant power node either as a current source or as a parallel of current source and impedance. Both methods allow very fast convergence for complex meshed networks, and can therefore be adopted for diverse studies such as market analysis and N-1 redundancy analysis, among others.