Computation of the Load Flow at the Transformer in Distribution Grids with a Significant Number of Photovoltaic Systems using Satellite-derived Solar Irradiance Data

Doktorgradsavhandling i fornybar energi, Fakultet for teknologi og realfag, Universitetet i Agder 2016This thesis investigates the applicability of irradiance data provided by a weather satellite for the simulation of the high-resolution electric power load flow time series at a distribution grid transformer in an area with a significant number of residential PV systems. Up to the present, the feed-in tariff for renewable generators in Germany has encouraged the installation of a significant number of photovoltaic systems especially at the low voltage level. Current studies assume a further increase in the number of systems worldwide. The responsibility for the electric grid at this voltage level rests on the distribution system operators. However, the photovoltaic systems affect the characteristics of the electric grid and the distribution system operator needs more information than the current annual energy measurements can provide. One option that may contribute to the closing of information gap is the use of irradiance data derived from remote sensing technologies. The load flow of the distribution grid transformer at a specific test site in Ulm, Germany, is calculated as a time series of 15-minute average values for a year. The feed-in power of each photovoltaic system connected to the grid is calculated using satellite-derived irradiance data and empirical non-linear photovoltaic models. The irradiance data are provided by different sources to investigate the influence of the irradiance source. The feed-in power is calculated with an average bias of 0.04 kW/kWp independent of the rated power of the photovoltaic system and varies with both the calculation algorithms and photovoltaic system orientation data used. The consumption time series is modelled with three different load profile types and scaled to the annual energy consumption provided by the distribution system operator. The different results of the variations are compared based on statistical measures and threshold detections are expressed as scores. The bias of the satellite derived irradiance of around 5% affects the simulation of the feed-in power. Experiment show that feed-in energy is overestimated by 22% when using satellite irradiance while the use of locally ground-measured irradiance only results in an overestimation of 3%. However, the statistical description of the consumption time series based on annual values leads to an additional bias of at least 33% for the energy at the transformer level. These overestimations are also visible in the scores of threshold detection at both photovoltaic system and transformer levels. The accuracy of detecting feed-in power above 70% of the photovoltaic system rating depends on the irradiance data and the modelling of the systems. The average false alarm rate is above 52% for the investigated test site. The detection of reversal load flows at the low voltage transformer is overestimated leading to a false alarm rate of at least 12% of all 15 minutes averages when the sun is higher than 15◦. This work makes clear that the detection accuracy strongly depends on the accuracy of the input data. The validation of the simulation up-scaled to the medium voltage level shows the weakness of absolute-value only measurements at the substation. The simulations also shows reversal load flows at this level. However, these results cannot be validated due to the limitation of the measurements to absolute values. To conclude, the simulation of the feed-in power as well as the load flow at the transformer is overestimated at a local level such as a residential area. The main errors are caused by the load profile used followed by the satellite-derived irradiance. An accurate detection of events exceeding a threshold requires accurate input and model data. Overall the method is able to simulate the load flow at low voltage and medium voltage levels. The effects of a significant number of PV systems on the electric grid and load flows have to be considered in grid planning and grid operations. Satellite-based irradiance data provides an opportunity to achieve independence from ground-based measurements limited to one location. If available, the orientation angles should be taken into account for analysis and calculations at the low voltage level

Digital rock physics applied to squirt flow

Meshed small and big models with triangular elements on their surfaces (.stl files) and tetrahedral elements (.mphbin)

Quantifying residential PV feed-in power in low voltage grids based on satellite-derived irradiance data with application to power flow calculations

A scheme using satellite-derived irradiance measurements to model the feed-in power of residential photovoltaic (PV) systems in a low voltage distribution grid is described. It is validated against smart meter measurements from a test site with 12 residential PV systems in the city of Ulm, Germany, during May 2013 to December 2014. The PV feed-in power is simulated in a 15-min time resolution based on irradiance data derived from Meteosat Second Generation satellite images by the physically based retrieval scheme Heliosat-4. The PV simulation is based on the nominal power and location of the PV systems as provided by the distribution system operator. Orientation angles are taken from high resolution aerial laser-scan data. The overall average mean error of PV feed-in power is 4.6% and the average root-mean-squared error is 12.3% for the individual systems. Relative values are given with respect to the total installed power of 152.3 kWp. Sensitivity studies discuss the need for knowing the exact orientation angles of each individual PV system or the usefulness of a single ground-based measurement as alternative to satellite observations. As an application of the scheme, the modelling of the effect of the power flow from the residential PV on the load flow of the low voltage distribution grid transformer is described and illustrates the advantage of the discussed approach for distribution system operators

Combination of GD2-directed bispecific trifunctional antibody therapy with Pd-1 immune checkpoint blockade induces anti-neuroblastoma immunity in a syngeneic mouse model

Introduction: Despite advances in treating high-risk neuroblastoma, 50-60% of patients still suffer relapse, necessitating new treatment options. Bispecific trifunctional antibodies (trAbs) are a promising new class of immunotherapy. TrAbs are heterodimeric IgG-like molecules that bind CD3 and a tumor-associated antigen simultaneously, whereby inducing a TCR-independent anti-cancer T cell response. Moreover, via their functional Fc region they recruit and activate cells of the innate immune system like antigen-presenting cells potentially enhancing induction of adaptive tumor-specific immune responses. Methods: We used the SUREK trAb, which is bispecific for GD2 and murine Cd3. Tumor-blind trAb and the monoclonal ch14.18 antibody were used as controls. A co-culture model of murine dendritic cells (DCs), T cells and a neuroblastoma cell line was established to evaluate the cytotoxic effect and the T cell effector function in vitro. Expression of immune checkpoint molecules on tumor-infiltrating T cells and the induction of an anti-neuroblastoma immune response using a combination of whole cell vaccination and trAb therapy was investigated in a syngeneic immunocompetent neuroblastoma mouse model (NXS2 in A/J background). Finally, vaccinated mice were assessed for the presence of neuroblastoma-directed antibodies. We show that SUREK trAb-mediated effective killing of NXS2 cells in vitro was strictly dependent on the combined presence of DCs and T cells. Results: Using a syngeneic neuroblastoma mouse model, we showed that vaccination with irradiated tumor cells combined with SUREK trAb treatment significantly prolonged survival of tumor challenged mice and partially prevent tumor outgrowth compared to tumor vaccination alone. Treatment led to upregulation of programmed cell death protein 1 (Pd-1) on tumor infiltrating T cells and combination with anti-Pd-1 checkpoint inhibition enhanced the NXS2-directed humoral immune response. Conclusion: Here, we provide first preclinical evidence that a tumor vaccination combined with SUREK trAb therapy induces an endogenous anti-neuroblastoma immune response reducing tumor recurrence. Furthermore, a combination with anti-Pd-1 immune checkpoint blockade might even further improve this promising immunotherapeutic concept in order to prevent relapse in high-risk neuroblastoma patients

GD2-directed bispecific trifunctional antibody outperforms dinutuximab beta in a murine model for aggressive metastasized neuroblastoma

Background: Neuroblastoma is the most common extracranial solid tumor of childhood. Patients with high-risk disease undergo extremely aggressive therapy and nonetheless have cure rates below 50%. Treatment with the ch14.18 monoclonal antibody (dinutuximab beta), directed against the GD2 disialoganglioside, improved 5-year event-free survival in high-risk patients when administered in postconsolidation therapy and was recently implemented in standard therapy. Relapse still occurred in 57% of these patients, necessitating new therapeutic options. Bispecific trifunctional antibodies (trAbs) are IgG-like molecules directed against T cells and cancer surface antigens, redirecting T cells (via their CD3 specificity) and accessory immune cells (via their functioning Fc-fragment) toward tumor cells. We sought proof-of-concept for GD2/CD3-directed trAb efficacy against neuroblastoma. Methods: We used two GD2-specific trAbs differing only in their CD3-binding specificity: EKTOMUN (GD2/human CD3) and SUREK (GD2/mouse Cd3). This allowed trAb evaluation in human and murine experimental settings. Tumor-blind trAb and the ch14.18 antibody were used as controls. A coculture model of human peripheral blood mononuclear cells (PBMCs) and neuroblastoma cell lines was established to evaluate trAb antitumor efficacy by assessing expression of T-cell surface markers for activation, proinflammatory cytokine release and cytotoxicity assays. Characteristics of tumor-infiltrating T cells and response of neuroblastoma metastases to SUREK treatment were investigated in a syngeneic immunocompetent neuroblastoma mouse model mimicking minimal residual disease. Results: We show that EKTOMUN treatment caused effector cell activation and release of proinflammatory cytokines in coculture with neuroblastoma cell lines. Furthermore, EKTOMUN mediated GD2-dependent cytotoxic effects in human neuroblastoma cell lines in coculture with PBMCs, irrespective of the level of target antigen expression. This effect was dependent on the presence of accessory immune cells. Treatment with SUREK reduced the intratumor Cd4/Cd8 ratio and activated tumor infiltrating T cells in vivo. In a minimal residual disease model for neuroblastoma, we demonstrated that single-agent treatment with SUREK strongly reduced or eliminated neuroblastoma metastases in vivo. SUREK as well as EKTOMUN demonstrated superior tumor control compared with the anti-GD2 antibody, ch14.18. Conclusions: Here we provide proof-of-concept for EKTOMUN preclinical efficacy against neuroblastoma, presenting this bispecific trAb as a promising new agent to fight neuroblastoma

12-Month outcomes of transcatheter tricuspid valve repair with the PASCAL system for severe tricuspid regurgitation

Objectives We investigated the durability of tricuspid regurgitation (TR) reduction and the clinical outcomes through 12 months after transcatheter tricuspid valve repair (TTVr) with the PASCAL Transcatheter Valve Repair System. Background TTVr has rapidly developed and demonstrated favorable acute outcomes, but longer follow-up data are needed. Methods Overall, 30 patients (age 77 ± 6 years; 57% female) received PASCAL implantation from September 2017 to May 2019 and completed a clinical follow-up at 12 months. Results The TR etiology was functional in 25 patients (83%), degenerative in three (10%), and mixed in two (7%). All patients had TR severe or greater (massive or torrential in 80%) and heart failure symptoms (90% in NYHA III or IV) under optimal medical treatment. Single-leaflet device attachment occurred in two patients. Moderate or less TR was achieved in 23/28 patients (82%) at 30 days, which was sustained at 12 months (86%). Two patients underwent repeat TTVr due to residual torrential TR (day 173) and recurrence of severe TR (day 280), respectively. One-year survival rate was 93%; 6 patients required rehospitalization due to acute heart failure. NYHA functional class I or II was achieved in 90% and 6-minute walk distance improved from 275 ± 122 m at baseline to 347 ± 112 m at 12-month (+72 ± 82 m, p < .01). There was no stroke, endocarditis, or device embolization during the follow-up. Conclusions Twelve-month outcomes from this multicenter compassionate use experience with the PASCAL System demonstrated high procedural success, acceptable safety, and significant clinical improvement