Search

Integration of new energy sources will continuously encroach upon the startup capacity of conventional units， reducing system’s rotational inertia and frequency regulation capabilities. This leads to accelerated frequency changes and increased fluctuation amplitudes. Therefore， it is imperative for new energy units to provide active inertia support. However， the dynamic characteristics of new energy units differ significantly from synchronous generators， making traditional swing equations inadequate to fully reflect the dynamic process of frequency response in new-type power systems after disturbances. Therefore， an inertia model for new-type power systems is established to accurately characterize the inertia response process of synchronous generators， grid-following inverters， and grid-forming inverters. A real-time inertia measurement method is proposed， which employs an improved polynomial curve fitting method （PCFM） and system identification method to accurately identify the system’s rotational inertia and regional inertia. Finally， through simulation， a quantitative assessment of the equivalent inertia of new-type power systems is conducted， and the effectiveness of the proposed measurement method and mathematical model is validated.

Correct network topology is the basis of power grid analysis and control. Because of the lack of measurement on breakers， the identification of breaker states is particularly important in the distribution network. According to the characteristics of closed-loop construction and open-loop operation of the distribution network， section breaker graph is developed to describe the connectivity of the distribution network. The property of tree is used to describe the radial structure constraints of the operation of the distribution network. Based on the principle of weighted minimum absolute value， a identification model is developed， which aims to minimize the adjustments of breaker states and the sum of weighted absolute value of measurement errors. The proposed identification model is a mixed integer linear programming （MILP） problem in mathematic， which can be solved by the simplex method combined with the branch and cut frame. The correctness of proposed model and effectiveness of the proposed method are verified by simulation case.

A day-ahead optimal decision-making model is established for an integrated electricity-heat energy system to participate in both the electric energy market and the spinning reserve market, and the step-by-step carbon trading is introduced into the proposed model. The conditional value at risk method is used to manage the uncertainty risk of renewable energy and electrical load. With the objective to minimize the operation scheme cost and carbon emission cost, an operation plan is developed and the reserve resources are arranged for the integrated electricity-heat energy system. The results of a case study show that the proposed model improves the reliability, economy, and low-carbon level by taking the complementary advantages of the integrated energy system and reasonably arranging reserve resources to deal with the risks caused by uncertain factors.

Although enhanced performance of photovoltaic devices by embedding metal nanoparticles in charge transport layer, doping into active layer bulk, decorating the active layer surface, and inserting at the interface between semiconductor and the electrode were reported, the effect of incorporating metal NPs at the interface of single crystal semiconductor and perovskite is rarely tackled. Herein the effects of incorporating Ag nanoparticals (AgNPs) at p-Si/MAPbI3 perovskite interface on the photodiode performance were investigated. The results showed that compared with the reference device (without AgNPs) the photoresponsivity of the device incorporating AgNPs is greatly improved with the exception of light with wavelengths falling in the spectral range where AgNPs have strong optical absorption. This effect is extremely significant for relatively shorter wavelengths in the visible region, and a maximal improvement of around 10.6 times in photoresponsivity was achieved. The physical origin of the exception for spectral range that AgNPs have strong optical absorption is the cancelation of scatter resulted enhancement through AgNPs by band-to-band absorption resulted reduction of photocurrent, in which the generated electron has energy near the fermi level and the hole has large effective mass, which relax by nonradiative recombination, thus making not contribution to the photocurrent. More importantly, the AgNP decorated device showed much faster photo response speed than the reference device, and a maximal improvement of around 7.9 times in rise and fall time was achieved. These findings provide a novel approach for high responsive and high speed detection for weak light. [ABSTRACT FROM AUTHOR]

Grid-forming control is a promising solution for renewable power integration. This work presents a variable pairing scheme for the voltage controller of V/f controlled modular multilevel converter in an islanded network with a synchronous machine, which is a special type of grid-forming control. Based on the concept of the relative gain array (RGA), it is found that the RGA can be derived using steady-state sensitivity analysis. Then, the steady-state characteristics of the typical electrical components in the islanded network are considered, and the analytical expression for calculating the RGA is derived. Based on a typical system, a variable pairing scheme is then suggested using the calculated RGA elements. The time-domain simulations are conducted using PSCAD/EMTDC, and the results verify the feasibility and advantages of the suggested variable pairing scheme. [ABSTRACT FROM AUTHOR]

L-Arabinose isomerase (L-AI) has been commonly used as an efficient biocatalyst to produce D-tagatose via the isomerization of D-galactose. However, it remains a significant challenge to efficiently synthesize D-tagatose using the native (wild type) L-AI at an industrial scale. Hence, it is extremely urgent to redesign L-AI to improve its catalytic efficiency towards D-galactose, and herein a structure-based molecular modification of Lactobacillus plantarum CY6 L-AI (LpAI) was performed. Among the engineered LpAI, both F118M and F279I mutants showed an increased D-galactose isomerization activity. Particularly, the specific activity of double mutant F118M/F279I towards D-galactose was increased by 210.1% compared to that of the wild type LpAI (WT). Besides the catalytic activity, the substrate preference of F118M/F279I was also largely changed from L-arabinose to D-galactose. In the enzymatic production of D-tagatose, the yield and conversion ratio of F118M/F279I were increased by 81.2% and 79.6%, respectively, compared to that of WT. Furthermore, the D-tagatose production of whole cells expressing F118M/F279I displayed about 2-fold higher than that of WT cell. These results revealed that the designed site-directed mutagenesis is useful for improving the catalytic efficiency of LpAI towards D-galactose. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have been broadly applied in biomedical and other fields. MOFs have high porosity, a large comparative area, and good biostability and have attracted significant attention, especially in cancer therapies. This paper presents the latest applications of MOFs in chemodynamic therapy (CDT), sonodynamic therapy (SDT), photodynamic therapy (PDT), photothermal therapy (PTT), immunotherapy (IT), and combination therapy for breast cancer. A combination therapy is the combination of two different treatment modalities, such as CDT and PDT combination therapy, and is considered more effective than separate therapies. Herein, we have also discussed the advantages and disadvantages of combination therapy in the treatment of breast cancer. This paper aims to illustrate the potential of MOFs in new cancer therapeutic approaches, discuss their potential advantages, and provide some reflections on the latest research results. [ABSTRACT FROM AUTHOR]