Different active and reactive output power of the inverter in the grid-connected system can induce instability problems when the grid is a weak grid. Under the condition, it is important to obtain a stable operating area consisting of the active and reactive power. The system can avoid unstable operation when the output power of the inverter is in the stable operating area. The stability analysis method is the key to obtain the area. The existing analysis methods are conservative. Furthermore, it causes the output power to be wasted in the grid-connected system to keep the system stable. This paper presents an analytical method to overcome the above problem. The method obtains a stable boundary curve of the system operating area, which can divide stable and unstable regions. Then, an accurate stable operating area of the system is obtained. Finally, experiment results are presented to demonstrate the effectiveness of the proposed method.
Sixth-generation (6G) networks are evolving towards new features and order-of-magnitude enhancement of systematic performance metrics compared to the current 5G. In particular, the 6G networks are expected to achieve extreme connectivity performance with Tbps-scale data rate, Kbps/Hz-scale spectral efficiency, and $\mu$s-scale latency. To this end, an original three-layer 6G network architecture is designed to realise uniform full-spectrum cell-free radio access and provide task-centric agile proximate support for diverse applications. The designed architecture is featured by super edge node (SEN) which integrates connectivity, computing, AI, data, etc. On this basis, a technological framework of pervasive multi-level (PML) AI is established in the centralised unit to enable task-centric near-real-time resource allocation and network automation. We then introduce a radio access network (RAN) architecture of full spectrum uniform cell-free networks, which is among the most attractive RAN candidates for 6G TK$\mu$ extreme connectivity. A few most promising key technologies, i.e., cell-free massive MIMO, photonics-assisted Terahertz wireless access and spatiotemporal two-dimensional channel coding are further discussed. A testbed is implemented and extensive trials are conducted to evaluate innovative technologies and methodologies. The proposed 6G network architecture and technological framework demonstrate exciting potentials for full-service and full-scenario applications.
This paper is mainly devoted to investigating the migrativity equations involving nullnorms and 2-uninorms. Depending on whether the absorbing elements of 2-uninorms and unllnorms are same or not, all solutions of the migrativity equations for all possible combinations of the three defined subclasses of 2-uninorms and nullnorms are analyzed and characterized respectively. And for such equations, there are new solutions which extend the known ones about the migrativity for uninorms and nullnorms.
This paper aims to study the cross-migrative property for uninorms with different neutral elements. The cases for uninorms in Umin, Umax, representable uninorms, idempotent uninorms and uninorms continuous in the open unit square are studied, discussing cross-migrative property for all possible com binations of uninorms laying on these classes of uninorms. This study shows that there is no cross-migrativity between representable uninorms and other classes of uninorms, and the relation between conjunctive uninorms and disjunctive uninorms is also the same. The sufficient and necessary conditions such that cross-migrativity equation holds for all of the other possible combinations of uninorms are given out.
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