Review of trends and targets of complex systems for power system optimization

Optimization systems (OSs) allow operators of electrical power systems (PS) to optimally operate PSs and to also create optimal PS development plans. The inclusion of OSs in the PS is a big trend nowadays, and the demand for PS optimization tools and PS-OSs experts is growing. The aim of this review is to define the current dynamics and trends in PS optimization research and to present several papers that clearly and comprehensively describe PS OSs with characteristics corresponding to the identified current main trends in this research area. The current dynamics and trends of the research area were defined on the basis of the results of an analysis of the database of 255 PS-OS-presenting papers published from December 2015 to July 2019. Eleven main characteristics of the current PS OSs were identified. The results of the statistical analyses give four characteristics of PS OSs which are currently the most frequently presented in research papers: OSs for minimizing the price of electricity/OSs reducing PS operation costs, OSs for optimizing the operation of renewable energy sources, OSs for regulating the power consumption during the optimization process, and OSs for regulating the energy storage systems operation during the optimization process. Finally, individual identified characteristics of the current PS OSs are briefly described. In the analysis, all PS OSs presented in the observed time period were analyzed regardless of the part of the PS for which the operation was optimized by the PS OS, the voltage level of the optimized PS part, or the optimization goal of the PS OS.Web of Science135art. no. 107

Optimal location of charging stations in smart cities: A points of interest based approach

Electric vehicles (EV) have become one of the most promising transportation alternatives in recent years. Due to continuously increasing gas prices and CO2 taxes, while at the same time subsidies of electrified cars run into millions, many countries such as the USA, UK, and Germany intend to bring large amounts of EVs onto their roads in the near future. As a prerequisite, an adequate charging infrastructure is needed to supply these vehicles with electrical fuel. In this paper we present a point of interest based business intelligence system to determine the optimal locations for charging stations. The underlying methodology is exploiting the potential of Big Data by analyzing and evaluating real charging sessions on the one hand and urban trip destination for vehicle owners on the other hand. Based on that, we formulate schemes to calculate an optimal charging infrastructure. A case study for Amsterdam and Brussels validates our results

Evaluation of battery energy storage systems in the Norwegian power grid to cope with increased vehicle electrification

Regjeringen har satt salgsmål for å øke elektrifiseringen av kjøretøy i Norge. Målene inkluderer at nye personbiler skal være nullutslippskjøretøy innen 2025. I tillegg skal alle lette varebiler, tunge varebiler, 75% av langdistansebussene og 50% av lastebilene være nullutslippskjøretøy innen 2030. Dette resulterer i en økende etterspørsel etter ladeinfrastruktur, både oppdateringer av eksisterende ladestasjoner, for å øke effektuttak og etablering av nye stasjoner. Nye utfordringer oppstår med økt elektrifisering. Utbyggere av ladestasjoner opplever begrenset nettkapasitet, noe som fører til høye kostnader for å forsterke nettet. Med økende ladeeffekt øker også investeringene i å etablere ladestasjoner. Nettselskap erkjenner behovet for å forsterke det eksisterende nettet når ladestasjonsoperatører ber om høy effekttilkobling til nettet. Derfor bør blant annet aspekter som avvikende spenninger, overbelastning av strømnettet, forventet redusert fleksibilitet og økte overharmoniske spenninger vurderes for å sikre en sikker nettdrift. I denne avhandlingen har et batterilagringssystem (BESS) blitt undersøkt. Systemet ble presentert som en mulig løsning for å fortsette utviklingen av ladestasjoner som var ulønnsomme eller tidkrevende prosjekter. Avhandlingen bruker tre metoder: et litteratursøk, kvalitative informantintervjuer og en GAP-analyse. I litteraturgjennomgangen ble ni artikler inkludert for å undersøke den optimale måten å utnytte et batterilagringssystem på i kombinasjon med en hurtigladestasjon. Det ble gjennomført elleve informantintervjuer med aktører fra fem ulike grupper. Ladeoperatører, nettselskaper, leverandører av batterilagringssystemer, støtteordingsinformanten og store kjøretøybrukere ga en bred, informativ og tilstrekkelig forklaring av deres opplevelse av den nåværende situasjonen for ladeinfrastruktur i Norge. I tillegg bidro de til å belyse fremtidige krav og forventinger. Litteratursøket viste en generell interesse for å bruke batteri av ulike grunner. Noen av grunnene var å redusere nettleie, bidra til å avlaste distribusjonsnettet og øke lønnsomheten til ladestasjonen. Flere tjenester ble presentert, for eksempel nettstøtte, frekvenskontrolltjenester, lastflytting og energiarbitrasje. Ifølge informantene som ble intervjuet, er det en stor etterspørsel etter ladeinfrastruktur med høyere effekt. Ladeoperatørene bemerket avgifter ved nettilknytning på steder med lav kapasitet og høy nettleie, noe som førte til mindre lønnsomme prosjekter. Dette kan også føre til færre installasjoner av ladestasjoner og manglende evne til å møte etterspørselen i årene som kommer. Som en løsning på dette ble det innført batterier for å øke hurtigladestasjonenes fortjeneste. Ifølge aktørene i denne avhandlingen er høyere effekttopper på ladestasjoner, finansiering for tunge kjøretøy og større ladeeffekt noe de forventer mer av i fremtiden. I GAP-analysen ble det presentert kortsiktige og langsiktige løsninger med batterilagringssystemer for å takle den økte etterspørselen etter ladeinfrastruktur. I en kortsiktig periode kan nettselskap kjøpe batteritjenester for å støtte nettet og for å knytte kunder raskere til nettet. Nettselskapene kan også integrere et batteri på en hurtigladestasjon for å redusere nettavgiftene og anleggsbidragene. Til slutt, for den kortsiktige løsning, var støtteordninger en sentral del for å utvide ladeinfrastrukturen for tunge kjøretøy. Den langsiktige løsningen inkluderte ladeoperatører som kunne øke fortjenester ved å selge tjenester i de norske reservemarkedene, i tillegg til energiarbitrasje og utvidelse av ladestasjonstilbudet. I tillegg ble det presentert at batterioperatører kunne selge tjenester til ladeoperatører og nettselskap for økt effektuttak og nettstøtte. Det ble også gitt et forslag om finansiering av batteri i distribusjonsnettet hvor verdistabling ble prioritert. Å øke batterioperatørens lønnsomhet, i tillegg til å anerkjenne betydningen av en mulig fleksibilitetsressurs, ble sett på som en løsning på den økende etterspørselen etter ladeinfrastruktur når elbilandelen i Norge øker.The Norwegian Government has set sales targets to increase the electrification of vehicles in Norway. The targets include new passenger cars to be zero-emissions vehicles by 2025. In addition, all light vans, heavy vans, 75% of the long-distance buses and 50 % of the lorries should be zero-emission vehicles by 2030. This results in an increasing demand for charging infrastructure, both updating existing stations with higher power outputs and establishing new charging stations. New challenges arise with increased electrification. Charging station developers experience limited grid capacity, leading to high costs of reinforcing the grid. With growing charger powers, the investment in establishing stations also grows. Distribution system operators acknowledge the need of reinforcing the existing grid when charging station operators request high power grid-tie. Therefore, aspects of deviating voltages, power grid congestion, expected reduced flexibility and increased harmonic distortions, amongst others should be considered to ensure a safe grid operation. In this thesis, the use of a battery energy storage system (BESS) has been investigated. The system was presented as one possible solution to proceed with the development of charging stations for unprofitable and time-consuming establishments. The thesis includes three methodologies: a literature review, qualitative informant interviews, and a GAP analysis. In the literature review, nine articles were included to examine the optimal way of utilising a battery energy storage system in combination with a fast charging station. Eleven informant interviews, with stakeholders from five different groups, were conducted. Charge point operators, distribution system operators, battery energy storage system providers, a funding informant, and heavy vehicle users presented a wide, informative, and adequate explanation of their experiences with the current charging infrastructure in Norway. Additionally, they noted future demands and prospects. The literature review showed an overall interest in utilising BESS for various reasons; Reducing grid fees, helping alleviate the distribution grid, and increasing the profitability of the charging station were repeated. Several services were presented, such as grid support, frequency control services, load shifting, and energy arbitrage. According to the informants interviewed, there is a rapid demand for charging infrastructure with higher power output. However, charging operators noted fees when grid-tying at locations with low capacity and high power grid fees, leading to less profitable projects. This could result in fewer charging station installations and a failure to meet demand in the coming years. As a solution to this, implementing batteries to increase a fast charging station's profits was introduced. According to the stakeholders of this thesis, future prospects are higher power peaks at charging stations, funding for heavy vehicles, and greater power charging output. In the GAP analysis, short- and long-term solutions with battery energy storage systems to cope with the increased demand in charging infrastructure were presented. For a short-term period, The DSO may rent BESS services for grid support and to grid-tie customers faster. CPOs may also integrate a BESS at a FCS to lower the grid fees and investment contributions. Lastly, for the short-term solution, funding was a central part to expand the heavy vehicle charging infrastructure. The long-term solution included CPOs possible increase revenue by selling services in the Norwegian reserve markets, in addition to energy arbitrage and expanding their charging station offer. Additionally, BESS operators selling services to CPOs and DSOs for increased power outputs and grid support were presented. Lastly, a proposal on funding BESSs in the distribution grid and favouring value stacking was given. Increasing the BESS operator's profitability in addition to recognising the importance of a possible flexibility resource was seen as a reasonable solution to the growing demand for charging infrastructure in Norway

Optimization and Integration of Electric Vehicle Charging System in Coupled Transportation and Distribution Networks

With the development of the EV market, the demand for charging facilities is growing rapidly. The rapid increase in Electric Vehicle and different market factors bring challenges to the prediction of the penetration rate of EV number. The estimates of the uptake rate of EVs for light passenger use vary widely with some scenarios gradual and others aggressive. And there have been many effects on EV penetration rate from incentives, tax breaks, and market price. Given this background, this research is devoted to addressing a stochastic joint planning framework for both EV charging system and distribution network where the EV behaviours in both transportation network and electrical system are considered. And the planning issue is formulated as a multi-objective model with both the capital investment cost and service convenience optimized. The optimal planning of EV charging system in the urban area is the target geographical planning area in this work where the service radius and driving distance is relatively limited. The mathematical modelling of EV driving and charging behaviour in the urban area is developed

Enhancement of Charging Resource Utilization of Electric Vehicle Fast Charging Station with Heterogeneous EV Users

This thesis presents innovative charging resource allocation and coordination strategies that maximize the limited charging resources at FCS with heterogeneous EV users. It allows opportunistic EV users (OEVs) to exploit available charging resources with dynamic event-driven charging resource allocation and coordination strategies apart from primary EV users (PEVs) (registered or scheduled EV users). Moreover, developed strategies focus on the limited charging resources that are allocated for primary/ registered EV users (PEVs) of the FCS who access the FCS with specific privileges according to prior agreements. But the available resources are not optimally utilized due to various uncertainties associated with the EV charging process such as EV mobility-related uncertainties, EVSE failures, energy price uncertainties, etc. Developed strategies consider that idle chargers and vacant space for EVs at the FCS is an opportunity for further utilizing them with OEVs using innovative charging resource coordination strategies. This thesis develops an FCS-centric performance assessment framework that evaluates the performance of developed strategies in terms of charging resource utilization, charging completion and the quality of service (QoS) aspects of EV users. To evaluate QoS of EV charging process, various parameters such as EV blockage, charging process preemptage, mean waiting time, mean charging time, availability of FCS, charging reliability, etc are derived and analyzed. In addition, the developed innovative charging resource allocation and coordination strategies with resource aggregation and demand elasticity further enhance the charging resource utilization while providing a high QoS in EV charging for both PEVs and OEVs.publishedVersio