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The purpose of this paper is to examine how a coordinated control strategy for managing the active power reserve in isolated microgrids is presented. This methodology can be applied in those microgrids where a specified generator assumes the role of the isochronous generator for the overall system. The derived algorithm evaluates control actions in the on-line environment by solving a constrained dynamic optimization problem aimed at maximizing the overall spinning reserve and, in particular, the reserve offered by the master unit equipped with the isochronous governor controller. The solution of this problem is obtained by adopting the direct Lyapunov theorem applied to the Sensitivity theory, ensuring the algorithm’s stability. Tests performed on the experimental microgrid, which has been built at the Polytechnic University of Bari, demonstrated the ability of the proposed methodology to share the regulation burden among all sources and storage systems, establishing adequate reserve margins of the master unit. [ABSTRACT FROM AUTHOR]

This paper proposes a decentralized controller to coordinate the reactive power injections of PV generators in order to contribute to the voltage regulation in distribution networks. The control actions are evaluated in the real time by adopting an optimization methodology involving the sensitivity applied to the Lyapunov function. By this approach it is possible to derive an auto-adaptive algorithm that can be implemented on actual distribution network without implying additional costs for infrastructures. Computer simulations have been performed on a MV distribution system to demonstrate the effectiveness of the proposed control scheme at different operating conditions and to confirm its ability to work in the real time. [ABSTRACT FROM AUTHOR]

This paper proposes a centralized control methodology for optimizing nodal voltages of distribution networks by acting on the reactive power produced by PV-inverters. Control actions are centrally evaluated in real-time by solving a constrained dynamic optimization problem aimed at minimizing the voltage deviation from a reference value. The solution of this problem is obtained by adopting an algorithm operating in the continuous time domain based on a fast artificial dynamic system involving the sensitivity theory. By this approach the controller is able to promptly respond to any change in the system operating point, allowing its adoption in the continuous time domain. However, it must be considered that the injection of the reactive power provided by PV-inverters entails greater conduction and switching losses, causing a reduction in the active power output, thus implying less incomings. As a consequence, these additional operating costs have been analyzed and evaluated in order to establish an economic compensation mechanism able to guarantee fair reimbursement to PV generators engaged in this regulation service. Computer simulations performed on an MV distribution system, demonstrate the effectiveness of the proposed control scheme under different operating conditions, confirming its ability to control the network in real-time. [ABSTRACT FROM AUTHOR]

• Identify the main design features of different microgrids around the world. • This paper explores the main issues arising from the development of a microgrid. • An attempt to define potential solutions to overcome the main technical issues. • It defines guidelines for practical implementation and operation of microgrids. A microgrid is a small portion of a power distribution system with distributed generators along with energy storage devices and controllable loads which can give rise to a self-sufficient energy system. From the utility grid side, a microgrid is seen as an equivalent generator that is able to seamlessly disconnect and operate autonomously once a fault affects the main grid. The design, installation and operation of such systems lead to dealing with a number of technical and operational challenges including control, protection and infrastructure requirements. To help designers and researchers address these challenges and draw potential recommendations for practical microgrid implementations, in this paper a review of the main design features of existing microgrids is undertaken, also in light of the experience gained during the realization of the Prince Lab microgrid at Polytechnic University of Bari, Italy. The main control functions required to guarantee an economic, reliable and secure operation of a microgrid are also reviewed. Finally, key practical guidelines for monitoring, operation and implementation of microgrids are provided. [ABSTRACT FROM AUTHOR]

Background Bevacizumab (BVZ) is an antiangiogenic agent approved by the Food and Drug Administration that is used for the treatment of recurrent glioblastoma. Complications related to impaired healing may adversely affect patients resected for recurrent high-grade glioma (HGG) after treatment with BVZ. Objective To examine the complication rate, outcome, and tumor vasculature in patients resected for recurrent HGG after treatment with BVZ. Methods Data were reviewed retrospectively from patients undergoing surgery for recurrent HGG after treatment with BVZ. Results were compared with a control group of recurrently operated BVZ-naïve HGG. Tumor samples and magnetic resonance imaging scans were analyzed. Results Fifteen patients underwent HGG resection after progression after BVZ. Forty-four BVZ-naïve patients who underwent surgeries for tumor recurrence were included as controls. Median time from BVZ treatment to surgery was 30 days (2–107). Median overall survival from time of tumor diagnosis was 21.0 months (12–83.0), and median survival from post-BVZ surgery was 5.0 months (2.0–19.0), compared with 8.1 months in BVZ-naïve controls measured from time of their last reoperation. Five of the 15 patients survived 6 or more months after post-BVZ surgery. Nine patients developed postsurgical complications requiring intervention. Complication rates for surgery after BVZ treatment were 66.7% compared with 38.6% in the control group ( P = 0.077). We did not see overt changes in histopathology or immunohistochemistry staining; however, tumor vasculature in tumors resected after treatment with BVZ showed a significant decrease in mean vessel density. Conclusions Surgery for recurrent HGG may be feasible in a select group of patients. Mean tumor vessel density may be decreased after treatment with BVZ. [ABSTRACT FROM AUTHOR]