Advanced Materials Research Vols. 953-954

Abstract: The aims of this work were to investigate the influence of feedstock properties of different part of cassava residues (cassava rhizome (CR), cassava stalk (CS) and cassava leaf (CL)) and operating temperatures on the pyrolysis characteristics and the kinetic parameters. Pyrolysis experiments of three selected biomass feedstock were conducted using a fixed-bed reactor. It was shown that the bio-oil yield of cassava stalk reached the maxima at 600°C, and the char yield reduced with the temperature, whereas the gas yield increased with temperature. The cassava rhizome presented higher thermochemical reactivity than the other samples. The activation energy of cassava stalks was 37.57 kJ / mol and that of cassava rhizome (39.42 kJ / mol) increased slightly. The activation energy of cassava leaf (22.85 kJ / mol) was lowest of the three samples.

Abstract: The world is facing energy crisis and the search for renewable bio-energy is currently one of the most important issues. Energy plant as a kind of bio-energy feedstock has attracted more and more attention, especially its planting issue. Short rotation coppice (SRC) is used as a proxy for other energy plants. This paper investigates farmers’ planting decisions of SRC under the threat of regulatory taking which is rarely mentioned in the previous relevant literatures. We use real options approach and especially take the risk of regulatory taking into account to analyze whether or not to grow SRC instead of traditional crops on farmland. It turned out that the threat of regulatory taking reduces the investment threshold and stimulates farmers to grow SRC. In other words, the threat has potential to improve the development of bio-energy.

Abstract: A novel inverter control strategy to enhance the transient stability of grid-connected wind farm based on doubly-fed induction generator (DFIG) is presented. Adding transient angle control strategy in the rotor side converter active control loop, this can dissipate the system unbalancing energy and restrain the system oscillations by the variation of wind turbine speed. Adding transient voltage control strategy in reactive control loop, this can provide fast reactive power compensation and support the restoration and reconstruction of the grid voltage when fault occurred. The control strategy which can improve the transient Angle stability and transient voltage stability at the same time is put forward. Finally, a testing system including a DFIG-based wind farm is realized using DigSILENT/Power Factory, the strategy validation and the contribution to power system stability enhancement are verified by simulation.

Abstract: Taiwan is developing the renewable energy actively, in which the wind energy is seen as one of important resources. However, the suitable locations for wind farm constructions are less and less on the shore, and the trend of wind farm development in the future will toward to offshore where the installation capacity of the wind farm could reach hundreds of megawatts. As the installation capacity of the wind farm increases, the effects on the interconnected AC grid are also more notable. In this paper, the off-peak system in Taiwan is used as a studied system in which the Penghu area and Taiwan grid is connected by submarine cables. This study explores the wind farm transmission system including HVAC, HVDC, and hybrid HVAC-HVDC systems and compares the differences of their impact on the system.

Abstract: The development of new and renewable energy is the key to Chinas future energy strategy. The development of wind energy resources has been drawing our attention because of its unique advantages and it grew rapidly recently. At present, Chinas wind energy industry has come into large-scale stage of rapid development and has made remarkable achievements while it also faces great challenges. Based on the overview of wind energy resources and its development status in China, the problems and restrictive factors of Chinas wind energy industry were analyzed in this paper, and its proper strategies for further wind energy development were discussed also.

Abstract: Aimed at the high inertia and non-linear characteristics of yaw system, a parameter self –tuning fuzzy PID controller is designed. The controller can adjust the PID parameters based on the wind direction variation, and make the turbines track the coming wind timely to obtain maximum power output. Simulation results show that the controller has good real-time performance and robustness compared with the traditional PID control. It can lower the fluctuation and overshoot, and improve the stability of the yaw system significantly.

Abstract: Due to the defect of the traditional wind power generation equipment, the hydraulic-type wind power generation (HWPG) system has gained extensive attention. In order to study the generating stability of the HWPG system, we established the mathematic model of the off-network HWPG system in this paper; and built its simulation model by using MATLAB/Simulink to investigate the speed and power of the system with the sinusoidal input signal. The simulation results show that the output electric energy of the hydraulic type wind power is unstable. Therefore, to enhance the practical application effects of the off-grid HWPG system, we have to add a storage equipment or speed controller of the motor to improve the quality of output electric energy.

Abstract: To solve the voltage stability issue caused by wind speed random and fluctuations and dynamic reactive power regulation of DFIG, a new coordinated control strategy is proposed. The scheme of switching of capacitor bank is pre-performed based on the predicted wind power, then based on the variety relation analysis between active power and reactive power of DFIG, by regulating the reactive power of wind farm in real time and determining reactive power output, it implement the reactive power and voltage control. Therefore, this improvement can enhance voltage quality and reduce capacitor responding times. The simulation of a practical example shows that the control strategy is effective and feasible.

Abstract: Aiming at the problem of lack of engineering practice experience and corresponding technology research, this paper reveal the interactive mechanism of distributed wind power and power grid. Based on the actual network frame and planning network frame, this paper establish analysis database, analyze problem of voltage stability by large amount of wind power integration into power system, propose the adjustment measures of voltage, put forward operation control mode of distributed wind. These can be used to guide the large-scale development of distributed wind power, which makes the development of distributed wind power guided by resource type of guiding transition to grid type.

Abstract: The energy costs of island systems are usually higher than those of large grid systems. Therefore, majority of the countries worldwide usually initiate their plans for developing renewable energy on remote islands. The electricity cost of Matsu Islands accounted for roughly 5% of total annual deficit of Taiwan Power Company. Hence, power generation is a critical energy economics issue for the Matsu Islands. This study will examine the possibility of wind power integration into Matsu Islands and investigate the transient frequency response in this system when a fault or disturbance occurs. According to the simulation results, the main target of this study is to improve the system stability on the remote island systems, and achieve the maximum renewable energy penetration.