The application of DC grids is gaining more attention in office applications. Especially since powering an office desk would not require a high power connection to the main AC grid but could be made sustainable using solar power and battery storage. This would result in fewer converters and further advanced grid utilization. In this paper, a sustainable desk power application is described that can be used for powering typical office appliances such as computers, lighting, and telephones. The desk will be powered by a solar panel and has a battery for energy storage. The applied DC grid includes droop control for power management and can either operate stand-alone or connected to other DC-desks to create a meshed-grid system. A dynamic DC nano-grid is made using multiple self-developed half-bridge circuit boards controlled by microcontrollers. This grid is monitored and controlled using a lightweight network protocol, allowing for online integration. Droop control is used to create dynamic power management, allowing automated control for power consumption and production. Digital control is used to regulate the power flow, and drive other applications, including batteries and solar panels. The practical demonstrative setup is a small-sized desktop with applications built into it, such as a lamp, wireless charging pad, and laptop charge point for devices up to 45W. User control is added in the form of an interactive remote wireless touch panel and power consumption is monitored and stored in the cloud. The paper includes a description of technical implementation as well as power consumption measurements.
Residential electricity distribution grid capacity is based on the typical peak load of a house and the load simultaneity factor. Historically, these values have remained predictable, but this is expected to change due to increasing electric heating using heat pumps and rooftop solar panel electricity generation. It is currently unclear how this increase in electrification will impact household peak load and load simultaneity, and hence the required grid capacity of residential electricity distribution grids. To gain better insight, transformer and household load measurements were taken in an all-electric neighborhood over a period of three years. These measurements were analyzed to determine how heat pumps and solar panels will alter peak load and load simultaneity, and hence grid capacity requirements. The impacts of outdoor effective temperature and solar panel orientation were also analyzed. Moreover, the potential for smart grids to reduce grid capacity requirements was examined.
As the impact of our actions on the climate become more and more clear and environmental awareness is rising, the quest for increasing efficiency and lower environmental impact becomes very important. Efficiency is particularly important in the field of electricity consumption, which keeps on rising as electrification of our transportation, houses, offices and more continues worldwide. These loads and sustainable sources have one thing in common: Direct Current. To successfully respond to this growing usage of direct current (DC) systems it is important to provoke an evolution in the provision of DC infrastructure. The goal of this paper is to create a methodology to calculate and evaluate the power losses in both traditional AC grids and DC microgrids. This is done through simulation models made by Caspoc, a software for modeling and simulating physical systems in analog/power electronics, electric power generation/conversion/distribution and mechatronics. The results are compared on the quantifiable indicator: energy savings. The impact of cable losses and different converters is calculated through the simulation. This methodology and simulation strategy can be the basis for the optimal grid design in other infrastructures and cases. The model will be validated with intensive tests of household equipment in a later stage of the project, this paper focuses on the model and methodology itself. DOI: 10.1109/DUE.2014.6827760
AANLEIDING In het RAAK-MKB project ‘Gelijkspanning breng(t) je verder’ heeft De Haagse Hogeschool, specifiek de opleiding Elektrotechniek, ervaren dat de opkomst van het onderwerp ‘Gelijkspanning’ (ook wel DC) in het beroepenveld sterk samenhangt met ontwikkelingen in het vakgebied van ‘Vermogenselektronica’ of ‘Power Eletronics’. Het beroepenveld vraagt steeds vaker om steeds meer kennis op dit vakgebied, in het kader van bijvoorbeeld de energietransitie, Smart Grids, Internet-of-Things etc. Om deze kennis op een goed gestructureerde wijze over te dragen aan studenten, moeten er een aantal belemmeringen worden weggewerkt. Een van deze belemmeringen is de beperkte beschikbaarheid van kennis; het vakgebied is relatief nieuw en nog sterk in ontwikkeling. Binnen De Haagse Hogeschool is door de opleiding Elektrotechniek (met kennis van de nog weg te werken belemmeringen) de bewuste keuze gemaakt om zich binnen Nederland te willen profileren met het onderwerp ‘Gelijkspanning’. Vanuit het eerdere RAAK-MKB project ‘Gelijkspanning breng(t) je verder’ werden hiertoe een eerste vak en practicum ontwikkeld: Vermogenselektronica 1. Hierin worden beginselen van DC-DC omvormers behandeld. DC-DC omvormers zorgen voor het transformeren van DC-spanningen, om energie bij hoge spanningen en dus lage verliezen te kunnen transporteren. Vanaf het huidige collegejaar (2015-2016) is ook een tweede vak op dit gebied toegevoegd aan het curriculum: Vermogenselektronica 2: hierin worden DC-AC omvormers op hoofdlijnen behandeld. Deze omvormers zorgen ervoor dat veel gebruikte types motoren aangedreven kunnen worden met gelijkspanning. Deze hoofdlijnen staan in de ogen van het beroepenveld nog (te) ver af van toepassingen waarmee zij werken. Daarbij moet gedacht worden aan bijvoorbeeld elektrische mobiliteit (specifieke types motoren), verlichting (DC-DC), distributietechnieken (DC-DC op hogere vermogens) of slimme netten (integratie van energietechniek, communicatietechnologie en regeltechniek / embedded systems). DOELSTELLING Het doel van het project is het opstellen van een implementatiewijze ter verdere invulling van de onderwerpen ‘Gelijkspanning’ en ‘Vermogenselektronica’ in het curriculum van de opleiding Elektrotechniek voor de teamleider van Elektrotechniek van De Haagse Hogeschool om de gewenste profilering te kunnen realiseren. ACTIVITEITEN Vanuit de curriculum commissie van de opleiding Elektrotechniek wordt opdracht gegeven aan een apart team om het implementatievoorstel voor te bereiden. Hierin werken twee docent/onderzoekers samen met de teamleider en enkele extern specialisten. In vijf opeenvolgende stappen wordt op een top-down manier gewerkt aan 1. Formuleren competenties voor DC 2. Hoofdstromen curriculum inrichten 3. Uitwerken vakinhoudelijke gebieden Elektrotechniek (‘leeg vel papier’) 4. Koppelen opzet aan bezetting en kennis in het team en bij partners 5. Voorbereiden besluitvorming RESULTAAT Op deze wijze wordt een heldere visie ontwikkeld op het benodigde onderwijs om het onderwerp gelijkspanning gestructureerd aan te kunnen bieden. Daarbij gaat het om vakinhoudelijke kennis in vakken, met bijbehorende practica en projecten. Om deze kennis goed aan te bieden wordt nadrukkelijk ook de samenwerking met andere kennisinstellingen (zoals Zuyd Hogeschool en de TU-Delft) gezocht.
The integration of renewable energy resources, controllable devices and energy storage into electricity distribution grids requires Decentralized Energy Management to ensure a stable distribution process. This demands the full integration of information and communication technology into the control of distribution grids. Supervisory Control and Data Acquisition (SCADA) is used to communicate measurements and commands between individual components and the control server. In the future this control is especially needed at medium voltage and probably also at the low voltage. This leads to an increased connectivity and thereby makes the system more vulnerable to cyber-attacks. According to the research agenda NCSRA III, the energy domain is becoming a prime target for cyber-attacks, e.g., abusing control protocol vulnerabilities. Detection of such attacks in SCADA networks is challenging when only relying on existing network Intrusion Detection Systems (IDSs). Although these systems were designed specifically for SCADA, they do not necessarily detect malicious control commands sent in legitimate format. However, analyzing each command in the context of the physical system has the potential to reveal certain inconsistencies. We propose to use dedicated intrusion detection mechanisms, which are fundamentally different from existing techniques used in the Internet. Up to now distribution grids are monitored and controlled centrally, whereby measurements are taken at field stations and send to the control room, which then issues commands back to actuators. In future smart grids, communication with and remote control of field stations is required. Attackers, who gain access to the corresponding communication links to substations can intercept and even exchange commands, which would not be detected by central security mechanisms. We argue that centralized SCADA systems should be enhanced by a distributed intrusion-detection approach to meet the new security challenges. Recently, as a first step a process-aware monitoring approach has been proposed as an additional layer that can be applied directly at Remote Terminal Units (RTUs). However, this allows purely local consistency checks. Instead, we propose a distributed and integrated approach for process-aware monitoring, which includes knowledge about the grid topology and measurements from neighboring RTUs to detect malicious incoming commands. The proposed approach requires a near real-time model of the relevant physical process, direct and secure communication between adjacent RTUs, and synchronized sensor measurements in trustable real-time, labeled with accurate global time-stamps. We investigate, to which extend the grid topology can be integrated into the IDS, while maintaining near real-time performance. Based on topology information and efficient solving of power flow equation we aim to detect e.g. non-consistent voltage drops or the occurrence of over/under-voltage and -current. By this, centrally requested switching commands and transformer tap change commands can be checked on consistency and safety based on the current state of the physical system. The developed concepts are not only relevant to increase the security of the distribution grids but are also crucial to deal with future developments like e.g. the safe integration of microgrids in the distribution networks or the operation of decentralized heat or biogas networks.
Based on the model outcomes, Houtlaan’s energy transition will likely result in congestion and curtailmentproblems on the local electricity grid within the next 5-7 years, possibly sooner if load imbalance between phasesis not properly addressed.During simulations, the issue of curtailment was observed in significant quantities on one cable, resulting in aloss of 8.292 kWh of PV production per year in 2030. This issue could be addressed by moving some of thehouses on the affects cable to a neighboring under-utilized cable, or by installing a battery system near the end ofthe affected cable. Due to the layout of the grid, moving the last 7 houses on the affected cable to the neighboringcable should be relatively simple and cost-effective, and help to alleviate issues of curtailment.During simulations, the issue of grid overloading occurred largely as a result of EV charging. This issue can bestbe addressed by regulating EV charging. Based on current statistics, the bulk of EV charging is expected to occurin the early evening. By prolonging these charge cycles into the night and early morning, grid overloading canlikely be prevented for the coming decade. However, such a control system will require some sort of infrastructureto coordinate the different EV charge cycles or will require smart EV chargers which will charge preferentiallywhen the grid voltage is above a certain threshold (i.e., has more capacity available).A community battery system can be used to increase the local consumption of produced electricity within theneighborhood. Such a system can also be complemented by charging EV during surplus production hours.However, due to the relatively high cost of batteries at present, and losses due to inefficiencies, such a systemwill not be financially feasible without some form of subsidy and/or unless it can provide an energy service whichthe grid operator is willing to pay for (e.g. regulating power quality or line voltage, prolonging the lifetime of gridinfrastructure, etc.).A community battery may be most useful as a temporary solution when problems on the grid begin to occur, untila more cost-effective solution can be implemented (e.g. reinforcing the grid, implementing an EV charge controlsystem). Once a more permanent solution is implemented, the battery could then be re-used elsewhere.The neighborhood of Houtlaan in Assen, the Netherlands, has ambitious targets for reducing the neighborhood’scarbon emissions and increasing their production of their own, sustainable energy. Specifically, they wish toincrease the percentage of houses with a heat pump, electric vehicle (EV) and solar panels (PV) to 60%, 70%and 80%, respectively, by the year 2030. However, it was unclear what the impacts of this transition would be onthe electricity grid, and what limitations or problems might be encountered along the way.Therefore, a study was carried out to model the future energy load and production patterns in Houtlaan. Thepurpose of the model was to identify and quantify the problems which could be encountered if no steps are takento prevent these problems. In addition, the model was used to simulate the effectiveness of various proposedsolutions to reduce or eliminate the problems which were identified
