Application of Model Predictive Control Based on Kalman Filter in Solar Collector Field of Solar Thermal Power Generation

There are two prominent features in the process of temperature control in solar collector field.Firstly,the dynamic model of solar collector field is nonlinear and complex,which needs to be simplified.Secondly,there are a lot of random and uncontrollable,measurable and unmeasurable disturbances in solar collector field.This paper uses Taylor formula and difference approximation method to design a dynamic matrix predictive control(DMC)by linearizing and discretizing the dynamic model of the solar collector field.In addition,the purpose of controlling the stability of the outlet solar field salt temperature is achieved by adjusting the mass flow of molten salt.In order to further improve the ability of the system to suppress unmeasured disturbances,a steady-state Kalman filter is designed to estimate state variables,so that the system has better stability and robustness.The simulation verification results show that the DMC control system based on Kamlan filtering has better control effect than the traditional DMC control system.In the case of large fluctuations in solar radiation intensity and consideration of undetectable interference,the overshoot of the system is reduced by 4%and the rise time remains unchanged.

Research on Mixed Logic Dynamic Modeling and Finite Control Set Model Predictive Control of Multi-Inverter Parallel System

Parallel connection of multiple inverters is an important means to solve the expansion,reserve and protection of distributed power generation,such as photovoltaics.In view of the shortcomings of traditional droop control methods such as weak anti-interference ability,low tracking accuracy of inverter output voltage and serious circulation phenomenon,a finite control set model predictive control(FCS-MPC)strategy of microgrid multiinverter parallel system based on Mixed Logical Dynamical(MLD)modeling is proposed.Firstly,the MLD modeling method is introduced logical variables,combining discrete events and continuous events to form an overall differential equation,which makes the modeling more accurate.Then a predictive controller is designed based on the model,and constraints are added to the objective function,which can not only solve the real-time changes of the control system by online optimization,but also effectively obtain a higher tracking accuracy of the inverter output voltage and lower total harmonic distortion rate(Total Harmonics Distortion,THD);and suppress the circulating current between the inverters,to obtain a good dynamic response.Finally,the simulation is carried out onMATLAB/Simulink to verify the correctness of the model and the rationality of the proposed strategy.This paper aims to provide guidance for the design and optimal control of multi-inverter parallel systems.

Modeling and Simulation Analysis of Solar Thermal Electric Plants Based on Petri Net

At present,solar thermal power generation is in the demonstration stage,and the large-scale production is affected by many factors.In view of the characteristics of different operating modes of photothermal power generation,it is analyzed that the turbine needs to be started and stopped frequently due to different operating modes,which will lead to the instability of the output energy and the reduction of power generation efficiency.In this paper,the dynamic equation of energy conversion process is established by using the law of conservation of energy and conservation of mass.Combined with the logic switching criterion of the system,the system model was established by using the extended differential Petri net,and the validity and accuracy of the model were verified.Through the Petri net model of the system,the system’s working mode switching and power generation situation are analyzed due to the difference of direct normal irradiation intensity(DNI).Finally,the accuracy of the model is proved by comparing it with experimental data of the photovoltaic and thermal demonstration projects that have been connected to the grid.

Operation Strategy Analysis and Configuration Optimization of Solar CCHP System

This paper proposed a new type of combined cooling heating and power(CCHP)system,including the parabolic trough solar thermal(PTST)power generation and gas turbine power generation.The thermal energy storage subsystem in the PTST unit provides both thermal energy and electrical energy.Based on the life cycle method,the configuration optimization under eight operation strategies is studied with the economy,energy,and environment indicators.The eight operation strategies include FEL,FEL-EC,FEL-TES,FEL-TES&EC,FTL,FTL-EC,FTL-TES,and FTL-TES&EC.The feasibility of each strategy is verified by taking a residential building cluster as an example.The indicators under the optimal configuration of each strategy are compared with that of the separate production(SP)system.The results showed that the PTST-CCHP system improves the environment and energy performance by changing the ratio of thermal energy and electric energy.The environment and energy indicators of FEL-TES&EC are superior to those of FTL-TES&EC in summer,and the results are just the opposite in winter.The initial annual investment of the PTST-CCHP system is higher than that of the SP system,but its economic performance is better than that of the SP system with the increase of life-cycle.

FCS-MPC Strategy for PV Grid-Connected Inverter Based on MLD Model

In the process of grid-connected photovoltaic power generation,there are high requirements for the quality of the power that the inverter breaks into the grid.In this work,to improve the power quality of the grid-connected inverter into the grid,and the output of the system can meet the grid-connected requirements more quickly and accurately,we exhibit an approach toward establishing a mixed logical dynamical(MLD)model where logic variables were introduced to switch dynamics of the single-phase photovoltaic inverters.Besides,based on the model,our recent efforts in studying the finite control set model predictive control(FCS-MPC)and devising the output current full state observer are exciting for several advantages,including effectively avoiding the problem of the mixed-integer quadratic programming(MIQP),lowering the THD value of the output current of the inverter circuit,improving the quality of the power that the inverter breaks into the grid,and realizing the current output and the grid voltage same frequency and phase to meet grid connection requirements.Finally,the effectiveness of the mentioned methods is verified by MATLAB/Simulink simulation.

Effect of microstructure on the mechanical, thermal, and electronic property measurement of ceramic coatings

Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition（EPD） and physical vapor deposition（PVD） were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina（YSZ/Al2O3） composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load–displacement curve. Scanning electron microscope（SEM） examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li0.34La0.51 Ti O2.94（LLTO） on Si/Sr Ru O3（Si/SRO） substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy（TEM） reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent.

Enhancement of ionic conductivity and fracture toughness by infiltrating porous Li_(0.33)La_(0.56)TiO_(3) pellets

Although solid-state lithium electrolytes have the potential to reduce the safety issues associated with organic liquid electrolytes,disadvantages such as low total conductivity,large interface impedance,and delamination of the interface due to cyclic stress still need to be addressed.The solid-state lithium-ion conductor Li_(0.33)La_(0.56)TiO_(3)(LLTO) was prepared via a hydrothermal route by using CTAB as templates in this paper.Perovskite LLTO with micro-porous channels was obtained and the total conductivity is comparable to the non-porous LLTO.Porous LLTO pellets are infiltrated with the non-porous LLTO precursor solution,and the total conductivities of the infiltrated porous LLTO are all higher than those without infiltration.After infiltration,the porous LLTO calcined at 600℃ achieves the highest total conductivity,7.88×10^(-5) S/cm.The fracture toughness of the infiltrated LLTO is higher than that of the non-porous LLTO.The results demonstrate a new way to prepare solid-state lithium-ion conductors with high ionic conductivity and great tolerance to cyclic stress.

寻根小说文化特色词英译过程研究——以蓝诗玲版《马桥词典》英译本为例

本文以长篇寻根小说《马桥词典》及其英译本为例,探讨生态、物质、社会、宗教和语言五种类别文化特色词英译之过程,验证乔治·斯坦纳阐释学翻译过程理论对寻根小说文化特色词翻译的指导价值。研究发现:斯坦纳提出的翻译四步骤对寻根文学《马桥词典》中五类文化特色词的英译过程具有很强的解释力,对寻根文学的文化特色词英译具有实际的指导意义;通过直译加注、直译加音译、直译加意译、意译加音译等"补偿"方式,可以最大限度还原源语的语言和文化信息,甚至是得到源语所没有表现出来的价值。

Preparation of hybrid perovskite-type Li_(0.33)La_(0.56)TiO_(3)by adding ionic liquids

Perovs kite-type Li_(0.33)La_(0.56)TiO_(3)(LLTO)shows greate r advantages than organic liquid electrolytes to be used in all-so lid-state lithium-ion batteries with high energy densities.Ionic liquid[BMIM][BF4]was used to improve the properties of Li_(0.33)La_(0.56)TiO_(3)by attrition milling in this study.The microstructure,crystallinity and lithium-ion conductivity of the samples were measured by scanning electron microscopy(SEM),X-ray diffraction(XRD),and impedance spectroscopy(IS).The total ionic conductivities of the samples LLTO+x wt%[BMIM][BF4]increase upon adding[BMIM][BF4]and the maximum conductivity reaches4.71×10^(-4)S/cm when x=12.5 wt%.The enhancement of the total conductivity is ascribed to the bridging role of the ionic liquid among grains,as evidenced by the low activation energy of 0.17-0.25 eV and the SEM observation.The Li+transference numbers of the hybrid samples are all lower than that of the pure LLTO,indicating the existence of electronic conductions.The hybrid mate rial with a mixed conductivity and good stability in the atmosphere can find uses in all-solid-state lithium-ion batteries to improve the interface contact between electrolytes and electrodes.

Improved conditional differential attacks on lightweight hash family QUARK

Nonlinear feedback shift register(NFSR)is one of the most important cryptographic primitives in lightweight cryptography.At ASIACRYPT 2010,Knellwolf et al.proposed conditional differential attack to perform a cryptanalysis on NFSR-based cryptosystems.The main idea of conditional differential attack is to restrain the propagation of the difference and obtain a detectable bias of the difference of the output bit.QUARK is a lightweight hash function family which is designed by Aumasson et al.at CHES 2010.Then the extended version of QUARK was published in Journal of Cryptology 2013.In this paper,we propose an improved conditional differential attack on QUARK.One improvement is that we propose a method to select the input difference.We could obtain a set of good input differences by this method.Another improvement is that we propose an automatic condition imposing algorithm to deal with the complicated conditions efficiently and easily.It is shown that with the improved conditional differential attack on QUARK,we can detect the bias of output difference at a higher round of QUARK.Compared to the current literature,we find a distinguisher of U-QUARK/D-QUARK/S-QUARK/C-QUARK up to 157/171/292/460 rounds with increasing 2/5/33/8 rounds respectively.We have performed the attacks on each instance of QUARK on a 3.30 GHz Intel Core i5 CPU,and all these attacks take practical complexities which have been fully verified by our experiments.As far as we know,all of these results have been the best thus far.