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Optimal strategy for energy management of DC multi‑microgrids considering power loss
Weiliang Zhang,Hui Zhang,Na Zhi,Hanwei Wang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4
DC multi-microgrids (DC MMG) improve power supply efficiency. However, they also increase transmission power loss. To reduce the power loss of the DC MMG, an optimization strategy of energy management with an adaptive distribution coefficient is proposed in this paper. By adjusting the power distribution coefficient of each DC microgrid (DC MG), the power distribution of the DC MMG is optimized to reduce power loss. In addition, to quickly predict changes of the DC MG power, the traditional finite control set model predictive control (FCS-MPC) is improved. The duty cycle of the converter is directly calculated according to the change of the current. Finally, experimental verification and comparison show that the proposed method can minimize the power loss of a DC MMG and speed up the balance of power.
Xiaoqi Wang,Zheng Hou,Hanwei Zhang 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.9
This work investigates the physical layer secrecy of a multi-antenna hybrid satellite-terrestrial relay networks (HSTRN) with jamming, in which a satellite aims to make communication with a destination user by means of a relay, along with spatially random eavesdroppers. In order to weaken the signals of eavesdroppers, the conventional relay can also generate intentional interference, besides forwarding the received signal. Shadowed-Rician fading is adopted in satellite link, while Rayleigh fading is adopted in terrestrial link, eavesdropper link and jamming link. The analytical and asymptotic formulas for the system secrecy outage probability (SOP) are characterized. Practical insights on the diversity order of the network are revealed according to the asymptotic behavior of SOP at high signal-to-noise ratio (SNR) regime. Then, analysis of the system throughput is examined to assess the secrecy performance. In the end, numerical simulation results are presented to validate the theoretical analysis and point out: (1) The secrecy performance of the considered network is affected by the channel fading scenario, the system configuration; (2) Decrease of the relay coverage airspace can provide better SOP performance; (3) Jamming from the relay can improve secrecy performance without additional network resources.
Han, Wei,Jin, Zhen,Zhang, Guang The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.5
In this paper, by using fixed point theorems in cones, the existence of positive solutions is considered for nonlinear m-point boundary value problem for the following second-order dynamic equations on time scales $({\phi}(u^{\Delta}))^{\nabla}+a(t)f(t,\;u(t))=0$, t $\in$ (0, T), $u(0)=\sum\limits^{m-2}_{i=1}a_iu(\xi_i)$, $\phi(u^{\Delta}(T))=\sum\limits^{m-2}_{i=1}b_i{\phi}(u^{\Delta}(\xi_i))$, where $\phi$ : R $\rightarrow$ R is an increasing homeomorphism and positive homomorphism and ${\phi}(0)=0$. In [27], we obtained the existence results of the above problem for an increasing homeomorphism and positive homomorphism with sign changing nonlinearity. The purpose of this paper is to supplement with a result in the case when the nonlinear term f is nonnegative, and the most point we must point out for readers is that there is only the p-Laplacian case for increasing homeomorphism and positive homomorphism due to the sign restriction. As an application, one example to demonstrate our results are given.