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In the present study, antioxidant impacts of L‐ascorbyl palmitate (L‐AP) on 14 kinds of typical vegetable oils were studied, whose ratios of C18:1 to C18:2 ranged from 0.15 to 9.57. Regression analyses between vegetable oils and their micronutrient‐free counterparts revealed that the antioxidant capacity of L‐AP was closely related to concentrations of α‐, γ‐, and δ‐tocopherols instead of fatty acid compositions. Binary mixtures consisting of L‐AP and α‐, γ‐, or δ‐tocopherols exhibited desirable synergistic antioxidant effects in comparison with individual species. The optimal synergistic effects were found at ratios of L‐AP to α‐, γ‐, δ‐tocopherols, being 1:2–1:4. Further EPR spin trapping test figured out that the combined antioxidants reduced the total amount of spin adducts significantly during lipid oxidation, which were contributed by regenerating tocopherols from L‐AP. The results will highlight the application of L‐AP in protecting packed cooking oils after opening and during cooking. Practical applications: Vegetable oils packaged in 4–5 L bottles are one of the most important forms for home cooking. Although deoxygenation techniques are applied to increase their shelf life during storage, they will experience a more violent oxidation reaction after opening. The oils are typically oxidized to rancidity before ending up in consumption. L‐AP was therefore involved into the vegetable oils to prevent them from oxidation during uses. The results of study can help companies to select the optimal L‐AP addition amount according to different endogenous tocopherol types and contents in the target oil in order to extend the use life of the vegetable oil. [ABSTRACT FROM AUTHOR]

In UHVDC transmission system, the inverter station is located in different geographical locations, and there are two sections of lines in single pole of HVDC system, which brings challenges to the traditional closed line protection. In this paper, firstly, the structural characteristics of series connection mode and the output characteristics of each converter in case of line fault are analysed, and the adaptability of conventional line protection in series multiple receiving ends system is studied. According to the characteristics of UHVDC system with multiple receiving ends in series connection mode, a hierarchical protection strategy is proposed and verified in PSCAD model.

Power supply system made of asynchronous motor-synchronous generator sets (M-G sets) is often used as power supply for important loads. The system usually consists of two M-G sets. Unlike synchronous generators connecting to large power grid, the two generators in the system can have significant effect on the other when field loss fault occurs. If the protection settings are inappropriate, the two generators may trip one after another during a fault on a single generator, causing the important load losing all the power supply. This paper proposed a simulation and protection verification method based on the RTDS digital modelling for M- G sets including detailed excitation system. The modelling and simulation methods can effectively verify the reasonability of settings of the P-Q restriction of the excitation regulator and the PID controllers, and provide the important basis for the setting of over-current protection and loss of excitation protection, ensuring the safe operation of the power supply system made of M-G sets.