High voltage direct current (HVDC) emergency control can significantly improve the transient stability of an AC/DC interconnected power grid, and is an important measure to reduce the amount of generator and load shedding when the system fails. For the AC/DC interconnected power grid, according to the location of failure, disturbances can be classified into two categories: 1) interconnected system tie-line faults, which will cause the power unbalance at both ends of the AC system, as a result of the generator rotor acceleration at the sending-end grid and the generator rotor deceleration at the receiving-end grid; 2) AC system internal faults, due to the isolation effect of the DC system, only the rotor of the generator in the disturbed area changes, which has little impact on the other end of the grid. In view of the above two different locations of disturbance, auxiliary power and frequency combination control as well as a switch strategy, are proposed in this paper. A four-machine two-area transmission system and a multi-machine AC/DC parallel transmission system were built on the PSCAD platform. The simulation results verify the effectiveness of the proposed control strategy.
To keep genetic diversity, flowering plants have developed a self-incompatibility system, which can prevent self-pollination. It has been reported that calcium concentration in pistil papilla cells was increased after self-pollination in transformed self-incompatible Arabidopsis thaliana. In this study, we found that CML27 changed its expression level for both mRNA and protein when compared to transcriptome and proteome. At the same time, CML27 was expressed in the anther and pistil at a high level and reached up to 5-fold up-regulated expression in the pistil at 1 h post-pollination when compared to 0 min. In order to find out potential proteins that may interact with BoCML27, BoCML27 was expressed in and isolated from E. coli. After its co-incubation with Brassica oleracea pistil proteins, the products were separated on SDS-PAGE gels. We found a specific band at the position between 130–180 kDa. Through LC-MS-MS (Q-TOF) analysis, eight proteins were identified from the band. The proteins include 26S proteasome non-ATPase regulatory (26S), Phospholipase D, alpha 2 (PLDα2) involved in Ca2+ binding and Coatomer subunit alpha-2-like (Coatomer) involved in vesicle mediated transport. All of these identified proteins provide new insights for the self-incompatibility response in B. oleracea, specific for increasing Ca2+ concentration in pistil papilla cells.