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More and more gas reciprocating generator units are integrated into offshore platforms, due to their compact structure and high efficiency. This paper concentrates on the transient stability analysis of one special type of AC microgrids containing a gas reciprocating generator unit. Firstly, the operation principle for the gas reciprocating generator unit is presented, which mainly consists of a reciprocating internal combustion engine and a linear synchronous alternator (LSA). Afterwards, the mathematical model for the core part of the gas reciprocating generator unit LSA is proposed, based on the principle of armature reaction in traditional synchronous and asynchronous machines. Finally, the simplified model of the independent offshore power system with a gas reciprocating generator unit is derived, and numerical simulations on the transient stability of this typical AC microgrid are performed, from which the effectiveness and correctness of the LSA model are validated. The transient stability analysis method of the independent offshore power system and the mathematical model of LSA can provide beneficial guidance for the stable operation of other types of stand-alone AC microgrids.

With the continuous decline in the cost of distributed photovoltaic systems, distributed photovoltaic systems have met the conditions for user-side parity to grid-connected. Its grid-connected capacity and installation penetration rate in some areas have also continued to rise, which has greatly affected the safe and stable operation of the distribution network and the main network. After the high penetration rate of distributed photovoltaic is connected, while increasing the line loss and reducing the economy, it also raises the voltage of the user's grid connection point, increases the neutral line current, and affects the user's power supply quality and power safety. Large-scale access has even changed the operation of the Power grid. This paper analyzes the impact of distributed photovoltaics on the grid from the aspects of voltage rise, line loss, etc., and analyzes the characteristics of distributed photovoltaic output, and finally gives some suggestions to solve the problems of distributed photovoltaics.

We developed a novel method for constructing nearly random peptide library. Genomic DNAs extracted from tissue or cells of large genome species were digested with frequent cutter to produce short DNA fragments. These short fragments can be considered nearly random. Nearly random peptide libraries can be constructed by cloning the short fragments into appropriate expression vectors and transformation into host cells. Genomic DNA from one species can be digested with different restriction enzymes and ligated to different reading frames to produce several different libraries. In this study, we digested tobacco genomic DNA with two enzymes and cloned into three different reading frames to make totally six nearly random peptide libraries.

To deduce all potential ligands undiscovered experimentally by searching all the proteins containing same C-termini, which can bind a certain PDZ domain.We developed a JAVA program for searching short exact sequence matches at C-terminus. According to the known C-termini, which PDZ domains recognized experimentally, Swissprot database has been searched by this program for all potential ligands.Some PDZ domains may have more potential ligand proteins, which are undiscovered yet experimentally. These bioinformatic results also provide clues for studying functions of hypothetical proteins and PDZ domains' protein interactions in many different organisms.The results may provide useful clues for discovering potential functions of hypothetical proteins and new functions of known proteins.