The study examines the potential for extensive connection of photovoltaic (PV) production in the Swedish rural power grid, considering the case distribution grid (10kV) of Herrljunga Elektriska. Hourly PV production is calculated using radiation and temperature data together with information regarding building roofs in the studied area. Furthermore, hourly customer load data is aggregated, enabling detailed power flow simulations of the grid resulting in hourly voltages and currents for all nodes during 2014. Three cases with varying PV production are studied, using different thresholds for minimum annual radiation. Thus, roofs with lower annual radiation are excluded from the simulations, limiting PV production. The three cases considers annual radiation greater than 0 kWh/m2 , 700 kWh/m2 and 1000 kWh/m2. Simulations show that the distribution grid in Herrljunga maintains acceptable performance with respect to voltages and currents for the 1000 kWh/m2,year case, yielding an annual production of 30 % of consumption. The hosting capacity, which is an estimate of the amount of PV that can be connected to the grid, is therefore 30 %. In order to further examine grid limitations, weak parts of the grid are identified. These are situated in the peripheral parts of the grid, which is in accordance with earlier studies of intermittent power production in distribution grids. Additionally, low voltage grids in connection to these weaker parts of the distribution grid are simulated, showing no further limitations for hosting capacity.

The number of photovoltaic (PV) systems increases annually in Sweden and the installation rate increases every year. The Swedish Energy Agency predict more than a doubling of the amount of electricity generated from PV systems by the year 2025, compared with today’s numbers. There are certain challenges that arise when connecting PV systems to the electric grid, concerning quality of various grid parameters, including the voltage. First, there is a risk of voltage variations due to the lack of swing mass in the PV system, to counteract changes. Voltage variations can also occur due to the unpredictability of the power source which is solar radiation. Secondly, there is a risk of increased voltage when the power production from the PV system is maximized while the power demand is low. The purpose of this report was to help network operators to understand how grid-connected PV systems affect grid voltage levels, and what measures may be necessary to strengthen the grid in the face of a continued increase in PV system installation. A residential area in E.ON's low voltage grid in the municipality of Halmstad, Sweden, was studied, where approximately 20% of the customers currently have installed PV systems. The customers were distributed over 5 groups connected to the area’s substation. Measurements were carried out at the substation which showed that the power changed direction on sunny days. Measurements were also carried out at the customer's connection point, which showed voltage increases on sunny days. In addition, future scenarios were simulated where the PV installation rate in the area was increased to investigate the hosting capacity in the area, before grid strengthening measures were necessary to manage the solar installations. The results showed a variation between the groups regarding how well equipped they were for an expansion of PV installations, which was probably due to a combination of the distance to the substation and the number of customers in the group. The simulations showed how the voltage level depended on the distance to the grid station and on the number of PV systems. Network strengthening measures to cope with a future scenario with 100% installation rate were studied. Cable reinforcement was not a sufficient measure for two of the groups, a sectioning of the group was necessary.

Microproduction, also called distributed generation, is something that has become more and more popular in the electric grid. Microproduction can however lead to unacceptable performance if several units are installed in the same low voltage network. It is therefore good to know a limit where the performance of the low voltage network becomes unacceptable based on given parameters. This limit is usually called hosting capacity. In this report the hosting capacity with respect to voltage and current have been studied in three low voltage networks which are located in Falu Elnäts concession area. This has been done by simulations in a GIS-program where critical times of the grid have been simulated. When the hosting capacity had been decided attempts have been made to increase the hosting capacity with four different measures. The measures examined are line gain, tap changer, reactive compensation and voltage regulation in the form of MPV. For the investigated network the hosting capacity varied virtuously. For all three grids were too high voltage during low load with maximum power production however the reason that the performance of the grid became unacceptable. The reasons that the voltage became unacceptable at different amounts of microproduction depends mainly on four things. These were the voltage in the substation, the amount of customers in the grid, the quality of the lines and the line length between the customer and substation. The best measure to increase the hosting capacity in a net is line gain in the most of the cases. Tap changer and the voltage regulator MPV are however two other measures that are recommended, but mainly as temporary solutions. Reactive compensation on the other hand is something that isn’t recommended based on this report.

Two strong trends in society which may have a major impact on the electricity grid load in the near future are the expansion of micro production with solar cells, and the increasingly prominent role of electric cars in the automotive market. In this work, an attempt is made to develop standardized and not too time-consuming methods to study how different future scenarios with large-scale expansion of private micro production with solar cells, as well as a very proportion of cars are electric and being charged at home, affect the various parts of the network with regarding voltage levels and load rating. A number of assumptions about average size and production for solar cell installations, as well as about charging effects and charging behavior were made as input to the calculations. Two variants of methods were tested to carry out the calculations in Umeå Energy's network calculation program dpPower. In the first method, for each connection (at low voltage calculation) and mains station (at intermediate voltage calculation) a standardized production or consumption is specified which is then combined with the historical consumption which gives the worst case. The second, faster method uses a scale factor to increase or decrease a specific historical consumption so that the calculation is made for the worst case of net production/consumption in the calculated area that you want to study. The methods are deemed to work relatively well in assessing load levels, provided that when interpreting results, one is aware that mainly the scaling method can yield unrealistic figures for consumption and production at certain nodes. However, validation of the voltage calculations by comparison with data from electricity quality meters installed in certain network stations shows that the program in many cases exaggerates voltage drops. The difference to the measured values were up to 65%. Further studies of what causes the calculation errors need to be made in order to eliminate said causes before the proposed methods can be used for this purpose. / Två starka trender i samhället som kan innebära en stor inverkan på elnätets belastning i en nära framtid är utbyggnaden av mikroproduktion med solceller, samt elbilarnas allt mer framträdande roll på fordonsmarknaden. I detta arbete görs ett försök att ta fram metoder för att på ett standardiserat och inte allt för tidskrävande sätt studera hur olika framtida scenarier med storskalig utbyggnad av privat mikroproduktion med solceller, samt då en mycket stor andel av personbilsparken är elbilar som laddas hemma, påverkar nätets olika delar med avseende på spänningshållning och belastningsgrad. Ett antal antaganden om genomsnittlig storlek och produktion för solcellsinstallationer, samt om laddningseffekter och laddbeteende gjordes som indata till beräkningarna. Två varianter av metoder testas för att genomföra beräkningarna i Umeå Energis nätberäkningsprogram dpPower. Den första innebär att man för varje anslutning (vid lågspänningsberäkning) och nätstation (vid mellanspänningsberäkning) anger en standardiserad produktion eller förbrukning, som man sedan kombinerar med den historiska förbrukning som ger värsta fallet. Den andra, snabbare metoden innebär att man använder en skalfaktor för att öka eller minska en historisk förbrukning så att beräkningen görs för det värsta fall av nettoproduktion/förbrukning på det beräknade området man vill studera. Metoderna bedöms fungera relativt väl för att bedöma belastningsnivåer, förutsatt att man vid tolkningen av resultat är medveten om att främst skalningsmetoden kan ge orealistiska siffror för förbrukning och produktion i vissa knutpunkter. Validering av spänningsberäkningarna genom jämförelse med data från elkvalitetsmätare som finns installerade i vissa nätstationer visar dock att programmet i många fall beräknar för stora spänningsfall. I några fall var skillnaden mot det uppmätta värdet upp till 65%. Det gör att metoderna i dagsläget inte kan användas för att bedöma effekten på spänningshållning. Ytterligare studier om vad felberäkningarna beror på göras så att felen kan åtgärdas innan de föreslagna metoderna kan användas för detta syfte.

Att producera el hemma och vara mikroproducent blir idag mer och mer vanligt. Lokalnätet är till mesta del anpassat för konsumtion och kommer därmed stå inför utmaningar när det ska produceras effekt hos kunderna. I och med detta vill Skellefteå Kraft få en uppfattning om var och vad för problem som kan uppstå med ökad andel mikroproduktion. Det som undersökts är acceptansgräns, spänningsökning och överbelastning.

Detta arbete har med hjälp av acceptansgränser uppskattat hur mycket mikroproduktion som kan installeras i ett lågspänningsnät och resultatet presenteras som en karta över ett referensområde. Arbetet visar att det trots ett mycket starkt elnät i huvudsak är acceptansgränsen för spänningshöjning som kommer att vara begränsande. Det läggs fram tre förslag på åtgärder som underlättar införandet mikroproduktion. Mätning för att uppskatta återstående marginal till acceptansgränsen, vilket sedan kan fungera som ett beslutsunderlag för att tillåta mer installerbar effekt. Justering av transformatorns nominella spänning, vilket frigör utrymme för mer produktion. Möjligheten till begränsning av produktion under kritiska timmar medför att mer installerbar effekt kan tillåtas och det finns mer tid för genomtänkta investeringar. / This work has estimated the amount of microgeneration that may be installed in a low voltage grid based on hosting capacity limits and presents an overview of a reference area. The work shows that despite a very strong power grid, it is essentially the hosting capacity for voltage increase that will limit microgeneration production. Three proposals are given for measures that facilitate the introduction of microgeneration. Measurements to estimate the remaining margin to the hosting capacity limit, which serves as a decision base to allow more installable effect. Adjustment of the transformer's rated voltage, which increases the hosting capacity and allows more production. Production curtailment during critical hours means that more installable power can be allowed and there is more time for thoughtful investments.

The use of electricity from Distributed Energy Resources like wind and solar powerwill impact the performance of the electricity network and this sets a limit to theamount of such renewables that can be connected. Investment in energy storage andcommunication technologies enables more renewables by operating the networkcloser to its limits. Electricity networks using such novel techniques are referred toas “Smart Grids”. Under favourable conditions the use of these techniques is analternative to traditional network planning like replacement of transformers orconstruction of new power line.The Hosting Capacity is an objective metric to determine the limit of an electricitynetwork to integrate new consumption or production. The goal is to create greatercomparability and transparency, thereby improving the factual base of discussionsbetween network operators and owners of Distributed Energy Resources on thequantity and type of generation that can be connected to a network. This thesisextends the Hosting Capacity method to the application of storage and curtailmentand develops additional metrics such as the Hosting Capacity Coefficient.The research shows how the different intermittency of renewables and consumptionaffect the Hosting Capacity. Several case studies using real production andconsumption measurements are presented. Focus is on how the permitted amountof renewables can be extended by means of storage, curtailment and advanceddistributed protection and control schemes. / Användningen av el från förnyelsebara energikällor som vind och sol kommer att påverka elnätet, som sätter en gräns för hur mycket distribuerad energiproduktion som kan anslutas. Investeringar i storskalig energilager och användning av modern kommunikationsteknologi gör det möjligt att öka andelen förnyelsebarenergi genom att nätet kan drivas närmare sina gränser. Elnät med sådana nya tekniker kallas ofta för ”Smarta Elnät". Implementering av sådana smarta elnät kan vara ett alternativ till traditionell nätplanering och åtgärder som utbyte av transformatorer eller konstruktion av nya kraftledningen.Nätets acceptansgräns är ett objektivt mått för att bestämma gränsen för nätets förmåga att integrera ny förbrukning eller produktion. Målet är att skapa större transparens och bidra till ett bättre faktaunderlag i diskussioner mellan nätoperatörer och ägare av distribuerade energiresurser. Denna avhandling utökar acceptansgränsmetoden för tillämpning med energilager och produktions nedstyrning och utvecklar ytterligare begrepp så som acceptansgränsen koefficienten.Forskningen visar hur varierbarheten hos olika förnyelsebara energikällor samverkar med förbrukningen och påverkar nätets acceptansgräns. Flera fallstudier från verkliga elnät och med uppmätt produktion och konsumtion presenteras. Fokus är på hur den tillåtna mängden förnyelsebara energikällor kan ökas med hjälp av energilagring, kontrollerad produktionsnedstyrning och med avancerad distribuerade skydd och kontroll applikationer. / Nicholas Etherden works at STRI AB (www.stri.se) in Gothenburg, Sweden. When he is not pursuing his half-time PhD studies he works as a specialist consultant in the field of Power Utility Automation, specialising on the IEC 61850 standard for power utility automation (today widely used in substations as well as some wind parks, hydro plants and DER and Smart Grid applications such as vehicle-to-grid integration). The author of this thesis received his Master of Science in Engineering Physics from Uppsala University 2000. Side tracks during his engineering studies included studies in theoretical philosophy, chemistry, ecology and environmental sciences as well as chairing the Swedish student committee of the Pugwash Conferences on Science and Worlds Affairs and later board member of the International Network of Engineers and of Scientists for Global Responsibility (INES) and chair of Swedish Scientists and Engineers Against Nuclear Arms. He has been a trainee at ABB in Västerås Sweden and spent six years as developer and team leader for the application development of a new relay protection family (ABB IED 670 series). In parallel to his professional work he studied power system engineering at Mälardalens University and travelled to all continents of the world. Since 2008 he is responsible for the STRI IEC 61850 Independent Interoperability Laboratory and a member of IEC Technical Committee 57 working group 10 "Power system communication and associated data models” and UCA/IEC 61850 User group testing subcommittee. He is co-author of IEC 61850-1 and main contributor to “Technical Report on Functional Test of IEC 61850 systems” and has held over 25 hands-on courses around the world on IEC 61850 “Communication networks and systems for power utility automation”. / SmartGrid Energilager

This thesis develops methods to increase the amount of renewable energy sources that can be integrated into a power grid. The assessed methods include i) dynamic real-time assessment to enable the grid to be operated closer to its design limits; ii) energy storage and iii) coordinated control of distributed production units. Power grids using such novel techniques are referred to as “Smart Grids”. Under favourable conditions the use of these techniques is an alternative to traditional grid planning like replacement of transformers or construction of a new power line. Distributed Energy Resources like wind and solar power will impact the performance of the grid and this sets a limit to the amount of such renewables that can be integrated. The work develops the hosting capacity concept as an objective metric to quantify the ability of a power grid to integrate new production. Several case studies are presented using actual hourly production and consumption data. It is shown how the different variability of renewables and consumption affect the hosting capacity. The hosting capacity method is extended to the application of storage and curtailment. The goal is to create greater comparability and transparency, thereby improving the factual base of discussions between grid operators, electricity producers and other stakeholders on the amount and type of production that can be connected to a grid.Energy storage allows the consumption and production of electricity to be decoupled. This in turn allows electricity to be produced as the wind blows and the sun shines while consumed when required. Yet storage is expensive and the research defines when storage offers unique benefits not possible to achieve by other means. Focus is on comparison of storage to conventional and novel methods.As the number of distributed energy resources increase, their electronic converters need to provide services that help to keep the grid operating within its design criteria. The use of functionality from IEC Smart Grid standards, mainly IEC 61850, to coordinate the control and operation of these resources is demonstrated in a Research, Development and Demonstration site. The site contains wind, solar power, and battery storage together with the communication and control equipment expected in the future grids.Together storage, new communication schemes and grid control strategies allow for increased amounts of renewables into existing power grids, without unacceptable effects on users and grid performance. / Avhandlingen studerar hur existerande elnät kan ta emot mer produktion från förnyelsebara energikällor som vindkraft och solenergi. En metodik utvecklas för att objektivt kvantifiera mängden ny produktion som kan tas emot av ett nät. I flera fallstudier på verkliga nät utvärderas potentiella vinster med energilager, realtids gränser för nätets överföringsförmåga, och koordinerad kontroll av småskaliga energiresurser. De föreslagna lösningarna för lagring och kommunikation har verifierats experimentellt i en forskning, utveckling och demonstrationsanläggning i Ludvika. / Godkänd; 2014; Bibliografisk uppgift: Nicholas Etherden är industridoktorand på STRI AB i Göteborg. Vid sidan av doktoreringen har Nicholas varit aktiv som konsult inom kraftsystemsautomation och Smarta Elnät. Hans specialitet är IEC 61850 standarden för kommunikation inom elnät, vindkraftparker och distribuerad generering. Författaren har en civilingenjörsexamen i Teknisk fysik från Uppsala Universitet år 2000. Under studietiden läste han även kurser i kemi, miljökunskap och teoretisk filosofi. Han var under studietiden ordförande för Student Pugwash Sweden och ledamot International Network of Engineers and of Scientists for Global Responsibility (INES). Efter studietiden var han ordförande i Svenska Forskare och Ingenjörer mot Kärnvapen (FIMK). Han började sin professionella bana som trainee på ABB i Västerås där han spenderade sex år som utvecklare och grupp ledare för applikationsutvecklingen i ABB reläskydd. I parallell till arbete har han läst elkraft vid Mälardalenshögskola. År 2008 började han på STRI AB som ansvarig för dess IEC 61850 interoperabilitetslab. Han är på uppdrag av Svenska Kraftnät aktiv i ENTSO-E IEC 61850 specificeringsarbete och svensk representant i IEC tekniska kommitté 57, arbetsgrupp 10 som förvaltar IEC 61850 standarden. Han har hållit över 30 kurser i IEC 61850 standarden i fler än 10 länder.; 20140218 (niceth); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Nicholas Etherden Ämne: Elkraftteknik/Electric Power Engineering Avhandling: Increasing the Hosting Capacity of Distributed Energy Resources Using Storage and Communication Opponent: Professor Joao A Peças Lopes, Faculty of Engineering of the University of Porto, Portugal Ordförande: Professor Math Bollen, Avd för energivetenskap, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Måndag den 24 mars 2014, kl 09.00 Plats: Hörsal A, Campus Skellefteå, Luleå tekniska universitet / SmartGrid Energilager