For reflecting grid connected operation control strategies, modeling of Battery Energy Storage System (BESS) was studied. The BESS models include two parts according to the infection to control results of State of Charge (SOC) of batteries. One is the electromechanical transient model, and the other is the long-term dynamic model. The convertor section of the models consider power control segment in normal operating mode, and fault crossing and protection segment reflecting output external characteristics in abnormal operating mode. In the capacity limit aspect, the actual voltage-SOC curve of battery is introduced in the models. Meanwhile, the charging and discharging characteristics can be simulated accurately. The validity of the proposed models is proved according to calculation results after taking BESS models into single generator system for simulation. In this paper, BESS models are established from the perspective of power grid and to realize the target of grid connected control, the models have generality, and they are suitable for electromechanical transient and long-term dynamic simulation. Therefore, the problems of present BESS models, that is being complex, reflecting charging / discharging characteristics of different batteries but no grid connected characteristics, and being not suitable for engineering application, can be solved.

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Modulation of the microstructure and configurational entropy tuning are the core stratagem for improving thermoelectric performance. However, the correlation of evolution among the preparation methods, chemical composition, structural defects, configurational entropy, and thermoelectric properties is still unclear. Herein, two series of AgSbTe2-based compounds were synthesized by an equilibrium melting–slow-cooling method and a nonequilibrium melting–quenching–spark plasma sintering (SPS) method, respectively. The equilibrium method results in coarse grains with a size of >300 μm in the samples and a lower defect concentration, leading to higher carrier mobility of 10.66 cm2 V–1 s–1 for (Ag2Te)0.41(Sb2Te3)0.59 compared to the sample synthesized by nonequilibrium preparation of 1.83 cm2 V–1 s–1. Moreover, tuning the chemical composition of nonstoichiometric AgSbTe2 effectively improves the configurational entropy and creates a large number of cation vacancies, which evolve into dense dislocations in the samples. Owing to all of these in conjunction with the strong inharmonic vibration of lattice, an ultralow thermal conductivity of 0.51 W m–1 K–1 at room temperature is achieved for the (Ag2Te)0.42(Sb2Te3)0.58 sample synthesized by the equilibrium preparation method. Due to the enhanced carrier mobility, optimized carrier concentration, and low thermal conductivity, the (Ag2Te)0.42(Sb2Te3)0.58 sample synthesized by the equilibrium preparation method possesses the highest ZT of 1.04 at 500 K, more than 60% higher than 0.64 at 500 K of the same composition synthesized by nonequilibrium preparation.

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