The last decade has witnessed a renewed interest in antimicrobial agents. Plants have received particular attention and frequently rely on the spontaneous enzymatic conversion of an inactive precursor to an active agent. Such two-component substrate/enzyme defence systems can be reconstituted ex vivo. Here, the alliin/alliinase system from garlic seems to be rather effective against Saccharomyces cerevisiae, whilst the glucosinolate/myrosinase system from mustard appears to be more active against certain bacteria. Studies with myrosinase also confirm that enzyme and substrate can be added sequentially. Ultimately, such binary systems hold considerable promise and may be employed in a medical or agricultural context.

This paper presents a new strategy of active synchronization of an island micro-grid and the utility grid (UG) without measurements at the point of common coupling (PCC). This strategy is based on the assistance of Ethernet communication, GPS pulse-per-second device synchronization, and droop control parameter shift. A strategy with Ethernetassisted synchronization is used instead of synchronization with dedicated low-bandwidth communication. This strategy is based on exchanging data between two proposed devices: synchronization data sender (SDS) and synchronization data controller (SDC). The SDS calculates the UG voltage parameters and sends these data to the SDC device. The SDC is responsible for receiving synchronization data and calculating droop control parameter shift. The use of GPS-based device synchronization adds very stable and accurate measurements of synchronization parameters that correspond to the stable synchronization signal. As this strategy uses droop control method parameter change, all distributed generators share loads adequately. This strategy introduces the possibility to remove the need for measurement of voltage directly on the switch location. The proposed devices could be connected even a long distance from the PCC. The strategy also introduces the possibility of working in synchronism with the main grid despite the island mode of the micro-grid. This introduces the possibility to connect the micro-grid at the same moment as fault clear or maintenance end.

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Purpose -In the dispersed generation system, power electronic converters allow for coupling between energy sources and the power grid. The requirements of Transmission System Operators are difficult to meet when the share of distributed energy sources of the total energy balance increases. These requirements allow to increase penetration of distributed generation sources without compromising power system stability and reliability. Therefore, in addition to control of active or reactive power, as well as voltage and frequency stabilization, the modern power electronic converters should support power grid in dynamic states or in the presence of nonlinear distortions. The paper aims to discuss these issues. Design/methodology/approach -The research methodology used in this paper is based on three steps: Mathematical modelling and simulation studies, Experiments on laboratory test stand, Analyzing obtained results, evaluating them and formulating the conclusions. Findings -The authors identified two algorithms, αβ-Filter and Voltage Controlled Oscillator, which are able to successfully cope with notch distortions. Other algorithms, used previously for voltage dips, operate improperly when the voltage grid has notching disturbances. This work evaluates six different synchronization algorithms with respect to the abilities to deal with notching.Research limitations/implications -The paper presents results of the synchronization algorithms in the presence of nonlinear notching interference. These studies were performed using the original hardware-software power grid emulator, real-time d'Space platform and power electronic converter. This methodology allowed us to exactly and accurately evaluate synchronization performance methods in the presence of complex nonlinear phenomena in power grid and power electronic converter. The results demonstrated that the best algorithms were αβ -Filtering and Voltage Controlled Oscilator. Originality/value -In this paper, different synchronization algorithms have been tested. These included the classical Phase Locked Loop with Synchronous Reference Frame as well as modified algorithms developed by the authors, which displayed high robustness with respect to the notching interference. During the tests, the previously developed original test rig was used, allowing software-hardware emulation of grid phenomena.

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