Time-series power flow simulations are consecutive power flow calculations on each time step of a set of load and generation profiles that represent the time horizon under which a network needs to be analyzed. These simulations are one of the fundamental tools to carry out cost-benefit analyses of grid planing and operation strategies in the presence of distributed energy resources, unfortunately, their execution time is quite substantial. In the specific case of cost-benefit analyses the execution time of time-series power flow simulations can easily become excessive, as typical time horizons are in the order of a year and different scenarios need to be compared, which results in time-series simulations that require a rather large number of individual power flow calculations. It is often the case that only a set of aggregated simulation outputs is required for assessing grid operation costs, examples of which are total network losses, power exchange through MV/LV substation transformers, and total power provision from PV generators. Exploring alternatives to running time-series power flow simulations with complete input data that can produce approximations of the required results with a level of accuracy that is suitable for cost-benefit analyses but that require less time to compute can thus be beneficial. This thesis explores and compares different methods for shortening time-series power flow simulations based on reducing the amount of input data and thus the required number of individual power flow calculations, and focuses its attention on two of them: one consists in reducing the time resolution of the input profiles through downsampling while the other consists in finding similar time steps in the input profiles through vector quantization and simulating them only once. The results show that considerable execution time reductions and sufficiently accurate results can be obtained with both methods, but vector quantization requires much less data to produce the same level of accuracy as downsampling. Vector quantization delivers a far superior trade-off between data reduction, time savings, and accuracy when the simulations consider voltage control or when more than one simulation with the same input data is required, as in such cases the data reduction process can be carried out only once. One disadvantage of this method is that it does not reproduce peak values in the result profiles with accuracy, which is due to the way downsampling disregards certain time steps in the input profiles and to the averaging effect vector quantization has on the them. This disadvantage makes the simulations shortened through these methods less precise, for example, for detecting voltage violations.

För att uppnå optimal resursdelning och öka hållbar energiförsörjning, stiger behovet av gränsöverskridande kraftöverföring ständigt. Därför frekventa utbyta information med detaljerade galler uppgifter krävs. För att standardisera sådant utbyte och därigenom främja gemensam kraftsystemstudier i Europa, Common Grid Model Exchange Standard (CGMES) grundar sig på IEC CIM (Common Information Models) utfärdats av ENTSO-E (European Network of Transmission Operators for Electricity) i 2013. En CGMES bedömning av överensstämmelse processen också inrättats att uppmuntra och undersöka antagandet av CGMES med relevanta kraftsystemtillämpningar. Huvudsyftet med denna avhandling är att validera att Network Manager produkten av ABB har genomfört CGMES ordentligt. Effektflödesberäkningar utförs baserat på ENTSO-Es provnäten och erhållna lösningarna jämförs med standard resultat samt resultaten från Power Factory (ett kraftsystem analysverktyg från DIgSILENT som redan har passerat bedömningen av överensstämmelse med framgång). Jämförelse resultaten analyseras alltså för att identifiera orsakerna till eventuella avvikelser från standardeffektflödeslösningar och ge förslag på framtida utveckling av Network Manager. / To achieve optimal resource sharing and enhance the sustainability of energy supply, the need for cross-border power transmission is continuously growing. Therefore, frequent information exchange with detailed grid data is required. To standardize such exchange and thus to facilitate common power system studies in Europe, the Common Grid Model Exchange Standard (CGMES) based on IEC CIM (Common Information Models) was issued by ENTSO-E (European Network of Transmission Operators for Electricity) in 2013. A CGMES conformity assessment process was also set up to encourage and examine the adoption of CGMES with relevant power system applications. The main purpose of this thesis is to validate that the Network Manager product of ABB has implemented CGMES properly. Power flow calculations are performed based on ENTSO-E’s test networks and the solutions obtained are compared with the standard results as well as the results from Power Factory (a power system analysis tool from DIgSILENT that has already passed the conformity assessment successfully).  The comparison results are analyzed thus to identify causes of any variation from the standard power flow solutions and to give suggestions for future development of Network Manager.

Kungälv Energi äger och ansvarar idag över Kungälv Kommuns elnät. Med en ökande befolkningsmängd ställs allt högre krav på elnätet och framför allt leveranssäkerheten. Med kalla vintrar och stort energibehov ger detta upphov till en svårare situation gällande leveranssäkerhet. I nuläget har Kungälv Energi två mottagarstationer, en 130/10kV-station espektive 130/20kV-station. 30/10kV-stationen börjar närma sig en gräns där effektbehovet närmar sig den maximala istributionskapaciteten. Därför fastställs en plan för att kunna klara av effektbehovet vid averi på en av två 130/10kV-transformatorer i mottagarstationen M1. Resultatet av rapporten visar att tillräcklig kapacitet finns i närliggande fördelningsstationer för att klara av reservdrift under hög belastning utan att några övriga komponenter skadas. Rapporten behandlar främst effektflöden för att kontrollera att dessa ej överskrider transformatorernas, ledningarnas och kablarnas märkeffekt. I flertalet fall har även faktorer för nödbelastning räknats med vilket resulterar i att samtliga linjer hos Kungälv Energi klarar av den ökade belastningen. Upptäckta flaskhalsar i nätet har uppmärksammats och delgetts samt förslag till förändringar för att förhindra framtida problem. / Kungälv Energi owns and is responsible of Kungälv municipality's electricity grid. With an increasing population and increasing demands on the grid and especially security of supply. With cold winters and large energy gives rise to a more difficult situation regarding security of supply. Currently, Kungälv Energi two receiving stations, a 130 / 10kV station and 130 / 20kV station. 130 / 10kV station is approaching a point where power demand is approaching the maximum distribution capacity. Therefore sets out a plan to cope with the power demand at the failure of one of two 130 / 10kV transformers of the receiving station M1. The results of the report shows that sufficient capacity is available in nearby distribution stations to cope with the emergency operation under high loads without any other components damaged. The report deals primarily with power flows to check that they do not exceed transformers, lines and cables rated power. In the majority of cases have also factors for distress load been counted with, which gives the result that all lines of Kungälv Energi can handle the increased load. Detected bottlenecks in the network have been highlighted, communicated and proposed changes to Kungälv Energi to prevent future problems.

This thesis deals with the issue of power flow analysis in a medium voltage (22kV) distribution network with a focus on the influence of distributed energy generation recources. At first the issue of operation of distributed energy resources and their reverse effects on the distribution system is presented in the thesis. Furtherly there are described their operational conditions from the legislation point of view. The part dealing with calculation compares two network configurations in terms of power quality and how the power quality is impacted by distributed energy resources. The attention is given to voltage conditions, short-circuit power, power conditions, losses and flicker. The first configuration corresponds to the real situation in the network, the other one is describing the changes after the new 110/22 kV substation implementation to the power supply area and the overal change of network configuration. The network model and run simulation is done using the E-Vlivy program.