With the rapid development of renewable energy sources such as wind power and photovoltaics, the penetration rate of power electronic equipment represented by grid-forming (GFM) and grid-following (GFL) converters in the power system has been increasing. The development of modern power systems is gradually showing a trend of high proportion of renewable energy and high proportion of power electronic devices (double-high), which profoundly changes the dynamic characteristics of modern power systems. Most of the converters in the power system adopt the GFL control strategy, which lacks the ability to support frequency and voltage. The converter with GFM control have gradually been incorporated into high-proportion renewable energy systems due to their voltage support and inertial response capabilities. However, the proportion configurations of GFM converter in the GFM/GFL hybrid system still needs to be further investigated. Therefore, this paper compares the basic principles and control methods of converters based on GFM strategy and GFL strategy, establishes the small-signal model of 100% REI system, and comparatively analyzes the dynamic characteristics of GFM and GFL converters. Secondly, a proportional configuration method for the GFM converter in 100% renewable electricity independent system (100% REI system) is proposed, and then through the small-signal model, the influence of different proportions of GFM converters and control mode on the stability of 100% REI system is discussed, the minimum configuration proportion of GFM converter to satisfy the stable operation of the system is explored. Finally, the correctness of the proportional configuration of GFM converters proposed in this paper and the engineering feasibility of independent operation of 100% REI system is verified.

Existing short-circuit calculation methods for distribution networks with renewable energy sources ignore the fluctuation of renewable sources and cannot reflect the impact of renewable sources and load changes on short-circuit current in real time at all times of the day and in extreme scenarios. A real-time short-circuit current calculation method is proposed to take into account the stochastic nature of distributed generators (DGs) and electricity loads. Firstly, the continuous power flow of distribution networks is calculated based on the real-time renewable energy output and electricity loads. And then, equivalent DG models with low-voltage ride through (LVRT) strategies are substituted into the iterative calculation method to obtain the short-circuit currents of all main branches in real time. The effects of different renewable energy output curves on distribution network short-circuit currents are quantitatively analyzed during the fluctuation in distributed power output, which can provide an important basis for the setting calculation of distribution network relay protection and the study of new principles of protection.

Many dietary flavonoids exist as glycosides in fruits and vegetables, and they are considered as bioactive food components potentially responsible for various health benefits. Type 2 diabetes mellitus is a complex and polygenic disease with increasing global prevalence. In this study, the inhibitory effects of avicularin (quercetin‐3‐O‐α‐arabinofuranoside), a flavonoid glycoside commonly found in apple and mango, were determined in the mice with high fat diet/streptozotocin induced type 2 diabetes. Our results demonstrated that dietary avicularin treatment (100 mg/kg/d) reduced levels of fasting blood glucose, TG and LDL‐C, improved β‐cell function, and suppressed hepatic steatosis in diabetic mice. Gene expression analysis by RNA‐Seq revealed that arachidonic acid metabolism, drug metabolism‐cytochrome P450, drug metabolism‐other enzymes, MAPK signaling pathway, metabolic pathways, metabolism of xenobiotics by cytochrome P450, p53 signaling pathway and retinol metabolism were the major pathways altered in the liver of the diabetic mice in comparison with that of the negative control mice (healthy mice). Within the type 2 diabetes mellitus related pathways, ADIPO, P13K, SOCS, VDCC, SUR1, GK, PYK genes were upregulated in diabetic mice compared to the healthy mice, and avicularin treatment significantly downregulated these genes in the diabetic mice. Within the PPAR pathways, the mRNA levels of FABP1, SCD‐1, SCP‐X, ADIPO, PEPCK were increased in the diabetic mice, and avicularin treatment effectively decreased the levels of these gens in the diabetic mice. Avicularin treatment also upregulated the genes such as CYP7A1, CYP8B1, and CYP4A1 that was downregulated in the diabetic mice in comparison with the healthy mice. Taken together, our results demonstrated the protective effects of avicularin against diabetes and provided a global view of the effects of avicularin on the complexity transcriptome in diabetic mice. Support or Funding Information This study was supported by the University of International Cooperation in Science and Technology Innovation Platform Project of Guangdong (2013gjhz0003), the Education Department of Guang zhou Province (Grant No. 2013J4100075), the National Natural Science Foundation of China (Grant No. 31201321).

The project of the flexible direct transmission of renewable energy has become an inevitable development trend for the large-scale grid connection of renewable energy. Its two-terminal weakly fed AC system is often composed of 100% power electronic equipment, which leads to an essential transformation in fault characteristics and protection requirements. At present, in research, the traditional directional elements are limited by the negative-sequence control strategy, resulting in the decline of their sensitivity and reliability. Therefore, this paper proposes a model for identifying directional elements using composite electrical quantities that is not affected by the control strategy of the two-terminal weakly fed AC system and can reliably identify the fault direction. Firstly, the adaptability of traditional directional elements under the negative-sequence current suppression strategy on both sides of the system when faults occur in the AC line was analyzed. Secondly, based on the idea of model recognition, the model relationship of fault voltage and current in the case of ground faults and non-ground faults occurring at different locations was analyzed. Finally, a fitted voltage was constructed and the Kendall correlation coefficient was introduced to achieve fault direction discrimination. Simulation results demonstrate that the proposed pilot protection scheme can operate reliably under conditions of 300 Ω transition resistance and 25 dB noise interference.