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2 2021

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A novel method for islanding in active distribution network considering distributed generation

Wang Jun, Wang Xinran, Di Bart, Sun Chao, Zheng Wei

Journal of Power Technologies

2021

Vol. 101, nr 1

11--20

The output of distributed generation (DG) has strong randomness, and its randomness has a great inuence on the division of islands. To simulate the impact of DG output on island division when dividing islands, this study proposed an island division method that considers the randomness of DG output. The basic idea of this method is as follows. First, Monte Carlo sampling was used to obtain the output power of DG under different confidence levels to simulate the randomness of DG output. Furthermore, a multi-objective and multi-constraint considering the randomness of DG output were established. The niche genetic algorithm was used to solve the model, and the effectiveness of the proposed model and algorithm was verified through the analysis of examples. The results show that the risk reserve power introduced by simulating the randomness of DG output is inversely proportional to the confidence level. The minimum value of the system node voltage level after islanding is 0.9495 pu, which meets the requirements of the constraint. Under the same conditions, compared with the island division method of not considering the random DG, the method proposed in this study not only has a larger total load recovery and a higher priority load recovery rate but also has a higher DG utilization rate, which can meet the needs of practical applications. This study provides a certain reference for the establishment and solution method of the islanding model of the distribution network with DG.

Study of the Effect of DINA on the Polymorphic Transition of ε-CL-20 in Composite Modified Double Base Propellants

Wu Zongkai, Zheng Wei, Pei Jiangfeng, Chen Zhiqun, Zhang Jun, Song Xiuduo, Wang Jiangning, Zhang Dongxiang, Zhao Fengqi

Central European Journal of Energetic Materials

2021

Vol. 18, no. 2

165--182

Abstract: The polymorphic transition of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05,9.03,11]dodecane (CL-20) is influenced by the materials and conditions used in the preparation of propellants, and limits the application of ε-CL-20 in solid propellants. In the present work, the effect of dinitroxydiethylnitramine (DINA) on the polymorphic transition of ε-CL-20 in CMDB propellants was investigated by Raman spectroscopy and the Calvet microcalorimeter method. The performance of propellants with CL-20 as affected by DINA was studied by the theoretical prediction of their energetic parameters, stability, combustion, and mechanical tests, respectively. The results showed that the polymorphic transition temperature of ε-CL-20 to α-CL-20 can be reduced to 75 °C by DINA. Expansion of the crystal volume during the process of the ε-CL-20 to α-CL-20 transition will produce obvious cracks in the surface of the crystals. NC/NG can inhibit the effect of DINA on the polymorphic transition of ε-CL-20. The theoretically predicted results indicated that adding DINA will not lower the energy level of CMDB propellants containing CL-20. The DSC and VST results showed that CL-20 has good compatibility and thermal stability with DINA. The burning rate tests revealed that adding DINA decreases the burning rates of CMDB propellants containing CL-20. Mechanical property testing showed that adding DINA can clearly improve the mechanical properties of CMDB propellants containing CL-20. The results of these investigations suggested that DINA has no effect on the crystalline stability of ε-CL-20 in the solventless extrusion process, which contributes to a significant understanding of practical applications and provides guidance for applied research on the use of CL-20 in propellants.