Advanced Materials Research Vols. 1070-1072

Abstract: One-step hydrotreatment of three different vegetable oils have been carried out over Pd loading bi-functional catalyst in batch reactor. Rubber seed oil, Jatropha oil and castor oil have different acid value and constituents, which will influence the hydroprocessing and the quality of products. With temperature rising, several principles have been summarized, and an optimal temperature corresponding to three oils have been determined respectively. At the optimal temperature of Jatropha oil, 300°C, deoxygenation rate was up to 99.29%, C_8-16 hydrocarbons of products was up to 77.36%; 310°C and 320°C were respectively optimal temperature of rubber seed oil and castor oil, deoxygenation rate were 99.15% and 98.78%, C_8-16 hydrocarbons were 71.46% and 69.25%. The products quality of Jatropha oil was better than rubber seed oil and castor oil, and rubber seed oil and castor oil can cause the deactivation of catalyst.

Abstract: Effects of different carbon source and Fe³⁺ for the growth and lipid accumulation of Monoraphidium sp. FXY-10 cultured mixotrophically was studied in our present work. The final cell density was reached to 2.626 g L^-1 when glucose was the only carbon source, which is 1.43-fold to sodium acetate (1.834 g L^-1), far higher than sucrose (0.251 g L^-1) and xylitol (0.471 g L^-1), but barely grow in other culture condition. Additionally, the highest algae lipid productivity (77.45 mg L^-1 d^-1) was obtained in 10 g L^-1 glucose group, which indicated that glucose was the optimal carbon source for growth and lipid accumulation of Monoraphidium sp. FXY-10. Nevertheless, Monoraphidium sp. FXY-10 was grew slowly in BG-11 culture medium with the absence of Fe³⁺. The biomass was achieved at the top with 50μM Fe³⁺ added. With the increase of Fe³⁺ concentration, it showed no variation in the growth of microalgae. The highest biomass productivity (209.87 mg L^-1 d^-1) was reached when the Fe³⁺ concentration was at 150μM while highest lipid productivity (94.05 mg L^-1 d^-1) reached at 50μM, which indicated that Fe³⁺ was one of the most indispensable trace elements for the growth and lipid accumulation of Monoraphidium sp. FXY-10.

Abstract: Currently, the problem of energy crisis and environmental deterioration on the world is extremely urgent, so people now are trying to turn to many kinds of renewable energy to solve these problems. Of these renewable energies, because of its cleanness and availability, wind power has broadened prospect and in recent years, it is considered to connect wind power to the grid in large quantities to make full use of it. However, wind power possesses the shortcoming such as randomness so that when it is connected to the grid, it may have great impact to the grid and damage the balance of the power system. Based on the fluctuation regularity of load and the characteristics of volatility, intermittent and randomness of wind power, the operation characteristics when large-scale wind power is connected to the grid and active regulation characteristics of conventional power source such as fire power, the multi time-scale “source to source” active coordinated control technique is proposed.

Abstract: It is of great significance for the safe and stable operation of power system to master the fluctuation characteristics of wind power output. On the basis of analyzing a large number of field measured data, a weighted mixed Gaussian probability model is proposed to simulate short-time wind power fluctuation characteristics of wind farm cluster, that evaluation indices to reflect the short-time maximum fluctuation of wind power output and maximum likelihood estimation algorithm based on Expectation Maximization (EM) to estimate model parameters are put forward. This model is compared with various other kinds of probability distribution model and the simulation results show that the weighted mixed Gaussian probability model possesses the highest precision, so as the effectiveness of the weighted mixed Gaussian probability model is verified.

Abstract: This paper, using the blade momentum theory combined with dynamic inflow correction and stall delay correction, analyses how periodic surge affect rotor aerodynamics of the NREL 5MW turbine operating at three different regions of its power curve. Results show that surge has the largest effects on rotor aerodynamics in region under rated wind speed while the smallest in region above that. Besides, oscillation amplitudes of rotor aerodynamic loads are in linear correlation with surge frequency and amplitude in most cases, except that rotor power and torque in region above rated wind speed is in linear correlation with the square of surge frequency. Results of this analysis would provide reference data for designs of floating wind turbine systems.

Abstract: Large-scale wind power integration will increase the transmission channel flow and the network loss. Use of high-energy load to participate in wind power accommodation, will have a considerable impact on the network loss. This paper proposes several mathematical models in which high-energy load access power grid in different voltage levels and does a detailed analysis of the mechanism of high-energy load’s participation in the wind accommodation by layer. Based on that, combined with the actual structure of Hexi grid, the software PSASP is adopted to do detailed simulation analysis, so as to verify the correctness of the theoretical derivation.

Abstract: Based on the background of structural overcapacity in wind power industry, this paper analyzes the stakeholders’ motivations and behaviors. With game theory, wind power feed-in, tax concessions and other key issues are discussed. Then this paper puts forward some optimal paths from government strategy, determination and allocation price policy and incentive policy, which provide theoretical guidance and practical value to achieve the overall development of wind power industry.

Abstract: This paper uses the optimal probabilistic load flow method for power containing wind farm analysis. Based on Computation of optimal load flow using the Interior point method ,considering the stochasticlal power output of wind generator and the random outage of synchronous generator and the stochastic of load power, calculating the probability distribution of branch power flow and node voltage. This paper uses RTS-24 as the example to analysis the method ,and comparison the results with that of the Monte-Carlo method, to analysis the change of power system after the grid connected of wind turbine.

Abstract: This paper firstly analyzes the mechanism of transmission line and transformer loss and illustrates the equivalent model and calculating method. Then creates a simple three-node model and discusses the main factors which affect the grid loss with adequate formula. At last, we draw a concise conclusion that there are several factors affecting grid loss. The main factors are the location of wind power access, the active power flow of transmission lines, the active power output of wind farms and the voltage level of wind power access.

Abstract: Currently, back-to-back converter is widely used in rectifier and inverter of direct-drive permanent magnet synchronous wind power system. But there are two shortages in the system, not stable of control effect and higher ripple of DC voltage. The dual-channel parallel boost converter can shunt the DC current, reduce the ripple effectively, and improve the quality of inverter side DC current. The paper uses the space vector pulse width modulation control strategy to control the inverter. Simplifying and decoupling the complex control system and control the DC bus voltage to remain stable. The simulation results confirm that dual-channel parallel boost converter have a better control effect than back to back converter, it through control the inverter to make power quality reached the grid connected requirement, verified the correctness of the design of inverter.