The grounding grid is an important part of ensuring the safety of power plants and substations, and its performance is directly related to the safety of people, equipment and power grids. After the ...grounding grid is running, due to the concealment of the project, it lacks sufficient technical means to evaluate it after it is put into operation, which has caused many difficulties for equipment operation, personnel safety and grounding grid maintenance. In order to solve the above problems, this paper uses CDEGS software to simplify the modeling of the grounding grid of a substation, and evaluates the performance of the grounding grid by analyzing the soil resistance layered model, touch voltage, step voltage and other parameters of the grounding grid, and give an optimization plan.
In this paper, a fixed size least square - supported vector machine (LS-SVM) algorithm is proposed to estimate the state of health (SOH) of the lithium-ion battery. First, the battery constant ...current discharging voltage profiles are analyzed and partial discharge curve that can be employed to describe the attenuation of the battery's SOH are extracted, and the suitable voltage range is analyzed. The discharging time is regarded as the input variable of the model. Then the fixed size LS-SVM algorithm is employed, and the corresponding support vector is selected according to Renyi entropy. The model parameters are optimized based on Bayes framework. Experimental results validate that the new method proposed in this paper can effectively track the aging of batteries. Compared with the traditional supported vector machine (SVM), the fixed size LS- SVM requires only 10 support vectors to achieve the desirable SOH estimation.
To work against the annoying waggle of a two-dimensional overhead crane system, this paper puts forward a novel model predictive control (MPC) strategy to satisfy various control constraints, ...particularly the maximum swing angle threshold. In order to simplify the model and satisfy the requirements of embedding application conveniently, the trolley acceleration is employed to be control input. In addition, several critical constraints and soft conditions are added into the MPC, aiming to insure the system stability and improve the overall performance. Simulation results justify the feasibility and correctness of the proposed method.
In this paper, a novel velocity predicted method based on Wavelet Transform (WT) and Radial Basis Function Neural Network (RBF-NN) is introduced to achieve the predictive energy management for plug- ...in hybrid electric vehicles (PHEVs). Three cases including RBF-NN, 1 RBF-NN with WT and 2 RBF-NN with WT, are taken into account for comparison. The corresponding model predictive contorl (MPC) algorithm is employed to testify the improvement of fuel economy based on the predicted velocity profile. Simulation results show that the combined algorithm of 1 RBF-NN and WT can attain satisfactory performance, which increases the prediction accuracy by 7.31% compared with that by other two cases. In addition, the computational time of the proposed predictive method is 2.8649 ms, justifying that it can be efficiently employed in the practical application.
When disconnector is operated in Gas-Insulated Switchgear (GIS) substation, Very Fast Transient Over-voltage (VFTO) will be formed due to arc breakdown and reignition between the switch contacts. The ...transient electromagnetic field generated by the VFTO, can be coupled to the secondary cable by conduction or radiation. In this paper, the equivalent calculation circuit model of Capacitor Voltage Transformer (CVT) is established, the interference voltage of secondary cable is deduced and calculated, and the simulation model of interference voltage of secondary cable caused by VFTO in GIS substation is established based on EMTP software. The VFTO of the primary side and its conducted interference to the secondary cable are simulated and calculated, and the different protective measures and their protective effects are analyzed. The interference protective measures of the VFTO to the secondary cable in the GIS substation are summarized, and the relevant shielding and protective measures are put forward.
The event plane detector (EPD), installed in the Solenoid Tracker at the Relativistic Heavy-Ion Collider located at the Brookhaven National Laboratory is a plastic scintillator-based device that ...measures the reaction centrality and event plane in the forward region of the relativistic heavy-ion collisions. We used silicon photomultiplier (SiPM) arrays to detect the photons produced in the scintillator via the fiber connection. Signals from the SiPM arrays were amplified by the front-end electronic (FEE) board, and sent to the analog-to-digital converter (ADC) boards for further processing via the receiver(RX) board. The full EPD system consisted of 24 super-sectors (SSs); each SS was equipped with two SiPM boards, two FEE boards and two RX boards, and they corresponded to 744 readout channels. All these boards were mass produced at the University of Science and Technology of China, with a dedicated quality assurance (QA) procedures applied to identify any problems before deployment. This article describes the details of the QA method and the related test system. The QA test results are presented along with the discussions.
Lightning activities are easy to cause secondary equipment fault, affecting the safe and reliable operation of the substation. In this paper, the lightning current, tower, insulator string, overhead ...line, secondary cable, transformer, capacitor voltage transformer (CVT), earthing network and arrester are modeled by EMTP software. The simulation model of the whole substation is built, and the lightning overvoltage of the secondary equipment in the substation is simulated and analyzed. On the basis of common secondary side overvoltage protective measures, an overvoltage protective measure composed of zinc oxide arrester series transient suppression diode and LC low-pass filter is proposed, and the effectiveness of this protective measure is verified by simulation.
To improve the bioavailability and targeting effect to hepatic cells of volatile oil from Atractylodes macrocephala Koidz, the volatile oil was incorporated into liposomes by a improved process of ...rapid expansion of supercritical solutions (RESS). In this process, the liposomal materials and the volatile oil were dissolved in the mixture of supercritical carbon dioxide (SC-CO 2 )/ethanol and then the solution was sparyed into a buffer solution through a coaxial nozzle to form liposomes suspension.The physicochemical properties of the liposomes including structure, size of particle, entrapment ratio and loading efficiency were measured. The encapsulating performance of liposomes could be controlled by changing expansion process conditions such as pressure, temperature of SC-CO 2 and the amount of cosolvent in SC-CO 2 x (CH 3 CH 2 OH). Under the optimum conditions of 30MPa, 338K and x (CH 3 CH 2 OH)=15 %, the entrapment efficiency, drug loading, and average particle size of liposomes were found to be 82.18 %, 5.18 % and 173 nm respectively, which were complied with the standards of Chinese pharmacopoeia. The results indicate the improved RESS technique provide an innovative way for formation of liposomes loading multi-components extracted from Chinese traditional medicines.
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