Analysis and modeling of novel brushless exciter based on hybrid excitation topology
The exciter is a key component of the synchronous generator system with self-excited initiation. Based on the topology of hybrid excitation, this paper proposes a novel brushless exciter, which is suitable for an isolated power system. The parameters of the exciter are calculated by the numerical method based on finite element model, and the state space model is established. The experimental researches are carried out on a 3 kW prototype.
Research on self-excited initiation of a Medium-voltage DC (MVDC) multiphase synchronous generator-rectifier system
This paper has described the excitation system of a Medium-voltage DC (MVDC) multiphase synchronous generator-rectifier system and calculated the minimum frequency of the pilot-exciter needed for self-excited initiation. On this basis, a double closed-loop V/F control method is proposed according to the classical PI control algorithm for self-excited initiation. With the method, a prototype is constructed for test. The results show that both the self-excitation initiating and the speed-rising processes of the generator set have changed synchronously thus to reduce the time needed for MVDC multiphase synchronous generator-rectifier system to start and finish establishing the nominal DC voltage.
Fluctuating asymmetry as an indicator of stress: Implications for conservation biology.
Extinction can be attributed broadly to environmental or genetic stress. The ability to detect such stresses before they seriously affect a population can enhance the effectiveness of conservation programs. Recent studies have shown that within-individual morphological variability may provide a valuable early indicator of environmental and genetic stress.