Microgrid Energy Management with Flexibility Constraints: A Data-Driven Solution Method

Microgrid energy management is a challenging and important problem in modern power systems. Several deterministic and stochastic models have been proposed in the literature for the microgrid energy management problem. However, more accurate models are required to enhance flexibility of the microgrids when accounting for renewable energy and load uncertainties. This thesis proposes key contributions to solve the energy management problem for smart building (or small-scale microgrid). In Chapter 3, a deterministic energy management model is presented taking into account system flexibility requirements. Energy storage systems are deployed to enhance the grid flexibility and ramping capability. The objective function of the formulated optimization is to minimize the operation cost. Combined heat and power (CHP) units, which interconnect heat and electricity, are modeled. Thus, electricity and thermal generation and load constraints are formulated. To account for uncertainties of load and renewable energy resources (e.g., solar generation), a stochastic energy management model is proposed in Chapter 4. A data-driven chance-constrained optimization is based method is formulated. The proposed model is nonparametric that imposes no assumption on probability distribution functions (PDFs) of the random variables (i.e., load and renewable generation). Adaptive kernel density estimation is deployed to estimate a nonparametric PDF for each random variable. Confidence levels (risk levels) of the chance constraints are modified according to estimation errors. Several cases are simulated to analyze the deterministic and stochastic optimization models. The simulation results show that the proposed data-driven chance-constrained optimization with the flexibility constraints enhance reliability, resiliency, and economics of the microgrid energy systems. Note that these flexibility constraints avoid propagating solar and load fluctuations to the distribution feeder. That is smart building (microgrid) is capable of capturing fluctuations locally

Percutaneous management of complicated parapneumonic effusion and empyema after surgical tube thoracostomy failure in children: a retrospective study

PurposeWe aimed to evaluate the results of percutaneous management of complicated parapneumonic effusions (PPE) and empyema after surgical tube thoracostomy failure in children.MethodsA total of 84 children treated percutaneously after surgical tube thoracostomy failure between 2004 and 2019 were included to this retrospective study. Technical success was defined as appropriate placement of the drainage catheter. Clinical success was defined as complete resolution of infection both clinically and radiologically. Management protocol included imaging-guided pigtail catheter insertion, fibrinolytic therapy, serial ultrasonographic evaluation, catheter manipulations as necessary (revision, exchange, or upsizing), and appropriate antibiotherapy. All patients were followed up at least 6 months.ResultsTechnical success rate was 100%. Unilateral single, unilateral double, and bilateral catheter insertions were performed in 73, 9, and 2 patients, respectively. Inserted catheter sizes ranged from 8 F to 16 F. Streptokinase, urokinase, and tissue plasminogen activator were used as fibrinolytic agent in 29 (34%), 14 (17%), and 41 (49%) patients, respectively. In order to maintain effective drainage, 42 additional procedures (catheter exchange, revision, reposition, or additional catheter placement) were performed in 20 patients (24%). Clinical success was achieved in 83 of 84 patients (99%). Median catheter duration was 8 days (4–32 days). Median hospital stay during percutaneous management was 11.5 days (7–45 days). Factors affecting the median catheter duration were the presence of necrotizing pneumonia (p < 0.001) and bronchopleural fistulae (p < 0.001).ConclusionPercutaneous imaging-guided catheterization with fibrinolytic therapy should be the method of choice in pediatric complicated PPE and empyema patients with surgical tube thoracostomy failure. Percutaneous treatment is useful in avoiding more aggressive surgical options

A Time Decomposition and Coordination Strategy for Power System Multi-Interval Operation

This paper presents a time decomposition strategy to reduce the computational complexity of power system multi- interval operation problems. We focus on the economic dispatch problem. The considered scheduling horizon is decomposed into multiple smaller sub-horizons. The first time interval of each sub- horizon is modeled as the coupling interval between two consecutive sub-horizons. The interdependencies between the sub- horizons are mathematically modeled using ramp rates of generating units. A distributed coordination strategy, which is based on auxiliary problem principle, is developed to coordinate the economic dispatch solutions of the sub-horizons to find an optimal solution for the whole operation horizon. We also propose an initializing technique to start the iterative coordination algorithm from a good-enough point. This technique enhances the convergence rate significantly. The proposed algorithm is deployed to solve a week-ahead economic dispatch problem on the IEEE 118-bus system, and promising results are obtained

Data-Driven Nonparametric Chance-Constrained Optimization for Microgrid Energy Management

In this article, we present a data-driven nonparametric chance-constrained optimization for microgrid energy management. The proposed approach imposes no assumption on probability density and distribution functions of solar generation and load. Adaptive kernel density estimator is utilized to construct a confidence set for each random parameter based on the historical data. The constructed confidence sets encompass the ambiguous true distribution and density functions. The concept of phi -divergence tolerance is applied to compute the distance between the estimated and true probability distribution functions (PDF)s. The estimated distributions are used to formulate a set of data-driven nonparametric chance constraints and model system/component restrictions. To account for the impact of errors in the forecast distributions on system economics and security, confidence levels of the chance constraints are adjusted with respect to pointwise errors of the estimated PDFs. This adjustment ensures that the microgrid chance constraints are satisfied with a predetermined confidence level even if the true realizations of solar generation and load do not exactly fit on the estimated PDFs. The chance constraints are converted into algebraic constraints. Numerical results show the effectiveness of the proposed approach for microgrid management

Palliation Of Malignant Gastroduodenal Obstruction: Fluoroscopic Metallic Stent Placement With Different Approaches

PURPOSE We aimed to evaluate the safety and effectiveness of fluoroscopy-guided gastroduodenal metallic stent placement with different approaches in malignant obstruction. METHODS We retrospectively assessed 53 patients (33 men and 20 women; mean age, 58.7 +/- 15 years) who underwent stent placement between February 2004 and April 2014. All patients had unresectable tumors. The most common causes of obstruction were gastric (38%) and pancreatic cancers (36%). Uncovered self-expandable metallic stents (SEMS) were placed under fluoroscopic guidance. In addition to transoral approach in 46 patients (86.7%), transgastric and transhepatic approaches were used in six patients (11.3%) and one patient (1.8%), respectively. Gastric outlet obstruction scoring system (GOOSS) was used to evaluate oral intake before and after stenting. Patients were followed until death or the end of the study. RESULTS Technical and clinical success rates were 100% and 92%, respectively. The median stent patency was 76 days (range, 4-985 days). Mean preprocedural GOOSS score of 0.1 increased to post-procedural GOOSS score of 2.42 (P < 0.001). Afferent loop decompression was achieved in one symptomatic patient. Neither mortality nor major complications occurred due to stenting. Stent migration occurred in one patient (2%) and stent obstruction occurred in two patients (4%). Combined biliary and duodenal stenting were performed in 21 patients (40%). Post-stenting GOOSS scores were predictive of survival (P = 0.003). CONCLUSION Fluoroscopic metallic stent placement for palliation of malignant gastroduodenal obstruction is safe and effective with high technical and clinical success rates and minimal complications. High technical success rates can be achieved using different approaches.Wo

Chance-constrained microgrid energy management with flexibility constraints provided by battery storage

Battery storage devices can potentially provide multiple services to microgrids. However, concurrent modeling and formulation of multiple services in grid management is a challenging problem. This paper proposes an energy management approach for microgrids including electrical and thermal forms of energy sources. The proposed approach takes advantage of battery storage devices for providing multiple services by applying chance-constrained optimization. The battery storage is deployed for 5-minute load following and energy arbitrage purposes. In addition, we have formulated a set of flexibility constraints, taking advantage of battery\u27s fast ramping capabilities, to enhance microgrid reliability in response to short-term solar power and load fluctuations. That is, the battery is deployed for load following, energy arbitrage, and regulation reserve procurement. Chance constraints are implemented to handle uncertainties of solar generation and load forecasting errors. Interdependencies between thermal and electrical energies are taken into account in the proposed approach. Numerical results show the effectiveness of the proposed approach to handle uncertainties, alleviate the short-term fluctuations, and enhance grid flexibility and reliability

Us-Guided Botulinum Toxin Injection For Excessive Drooling In Children

PURPOSE We aimed to evaluate the safety and efficacy of botulinum toxin A (BTX-A) injections under ultrasonography (US) guidance for children with excessive drooling. MATERIALS AND METHODS Between January 2006 and January 2011,44 BTX-A injections into bilateral submandibular glands were performed in 20 children (mean age, 9.1 years; ran e, 3-16 years; gender, 151 boys and 5 girls) under intravenous Sedation. Efficacy of the injections was evaluated 4-12 weeks after the injection. Severity of drooling was assessed using the Teacher Drooling Scale (TDS). If the patient or the patient's caregiver reported a good initial response, injections were then repeated periodically when drooling reached the preinjection score. If there was no response or suboptimal response, a booster injection of BTX-A was given after one month. RESULTS Technical success rate was 100%. No procedure-related major or minor complication was detected. One family (5%) reported intermittent problems with swallowing due to viscous saliva. A successful outcome was defined as a minimum two point reduction in TDS score. This outcome occurred. for 8 of 20 patients four weeks after the first injection. After consecutive sessions, clinical success was achieved at the end of the 12 weeks for 16 patients (80%). The mean TDS score decreased from 4.75 to 2.1 at the end of the study for all patients (P < 0.05). Four patients did not respond to BTXA injection. Submandibular resection was applied to 3 of 4 unresponsive patients. Two patients had complete remission after surgery, but one patient showed excessive drooling that could not be controlled. CONCLUSION US-guided submandibular BTX-A injection is a safe and effective procedure in treating drooling in children. It can be performed under intravenous sedation and does not require general anesthesia

Pelvic Abscess Drainage: Outcome With Factors Affecting The Clinical Success

PURPOSE We aimed to evaluate the success and complication rates of image-guided pelvic abscess drain age with emphasis on factors affecting the clinical success. METHODS During a 7-year period, 185 pelvic abscesses were treated in 163 patients under ultrasonography and fluoroscopy (n=140) or computed tomography (n=45) guidance with transabdominal (n=107), transvaginal (n=39), transrectal (n=21) and transgluteal (n=18) approaches. Abscess characteristics (etiology, number, size, intrastructure, microbiological content, presence of fistula), patient demographics (age, sex, presence of malignancy, primary disease, antibiotic treatments), procedure-related factors (guidance method, access route, catheter size) and their effects on clinical success, complications, and duration of catheterization were statistically analyzed. RESULTS Technical and clinical success rates were 100% and 93.9%, respectively. Procedure-related mortality or major complications were not observed. Minor complications such as catheter dislodgement, obstruction, or kinking were detected in 6.7% of the patients. Clinical failure was observed in 10 patients (6.1%). Fistulization was observed in 14 abscesses. Fistulization extended the duration of catheter use (P < 0.001) and decreased the clinical success rate (P < 0.001). The presence of postoperative malignant, complex-multilocular abscesses, and fungus infection in the cavity extended catheter duration (P < 0.001, P = 0.018, and P = 0.007, respectively), whereas the presence of sterile abscess and endocavitary catheterization reduced the catheter duration (P = 0.009 and P= 0.011, respectively). CONCLUSION Image-guided pelvic abscess drainage has high clinical success and low complication rates. The only factor affecting the clinical success rate is the presence of fistula.WoSScopu

Radiofrequency Ablation for Lung Tumors: Outcomes, Effects on Survival, and Prognostic Factors

PURPOSE We aimed to evaluate the survival benefit achieved with radiofrequency (RF) ablation of primary and metastatic lung tumors and determine significant prognostic factors for recurrence-free survival. METHODS Forty-nine patients with lung cancer (10 primary and 39 metastatic) underwent computed tomography-guided percutaneous RF ablation between June 2005 and October 2013. A total of 112 tumors (101 metastatic and 11 primary non-small cell lung cancer) were treated with RF ablation. Tumor diameter ranged from 0.6 to 4 cm (median 1.5 cm). Effectiveness of treatment, complications, and survival were analyzed. RESULTS Primary success rate was 79.5% and local tumor progression occurred in 23 tumors. Among tumors showing progression, 10 were re-treated with RF ablation and secondary success rate was 87.5%. One-, two-, and three-year overall survival rates of 10 patients with primary lung cancer were 100%, 86%, and 43%, respectively. One-, two-, three-, four-, and five-year overall survival rates for 39 patients with metastatic lung tumors were 90%, 73%, 59%, 55%, and 38%, respectively. One-, two-, three-, and four-year overall survival rates for 16 patients with colorectal pulmonary metastases were 94%, 80%, 68%, and 23%, respectively. Complications occurred in 30 sessions (24.6%). Pneumothorax occurred in 19 sessions with seven requiring image-guided percutaneous chest tube drainage. Tumor status (solitary or multiple) and presence of extrapulmonary metastasis at initial RF ablation were significant prognostic factors in terms of recurrence-free survival. CONCLUSION RF ablation is a safe and effective treatment with a survival benefit for selected patients with primary and secondary lung tumors.Wo

Case Report: Role of Interventional Radiology in the Management of Patients with Alveolar Echinococcus: Successful Management of Three Cases

Alveolar echinococcus (AE) is an infestation by Echinococcus multilocularis. Partial hepatectomy or liver transplantation is the first choice of treatment. However, the disease is usually diagnosed at an unresectable stage. In those cases, invasion of the bile ducts and vessels, and necrosis in the center of the lesion lead to severe complications, such as cholangitis and liver abscesses. Palliative surgery has been reported to not offer advantages in management, and percutaneous and endoscopic interventions have become more prominent in management. In this case series, outcomes in three cases with unresectable AE were reported. In one of the cases, interventional procedures were used to manage the complications after surgery. In the second case, the cystic component was aspirated to decrease the size before the surgery and in the third case, it was used to drain biliary tree and no surgery was done.WoSScopu