电网频率特性是电力系统运行机理分析和控制策略研究的基础,主要研究微电网中涉及双向储能设备的频率特性分析问题。首先,对变流器的功频特性和调频原理进行总结和分析。在此基础之上,针对传统频率特性分析法存在的参考值问题、单电源...电网频率特性是电力系统运行机理分析和控制策略研究的基础,主要研究微电网中涉及双向储能设备的频率特性分析问题。首先,对变流器的功频特性和调频原理进行总结和分析。在此基础之上,针对传统频率特性分析法存在的参考值问题、单电源问题和单维度问题,提出双象限频率特性(dual quadrant frequency characteristic,DQFC)分析方法。该方法构建统一的功率参考体系,不但能实现传统分析方法的功能,而且可对双向储能设备和复杂多电源系统的一次调频、二次调频机理进行定性和定量分析。该多电源系统可由发电机组、无穷大电网、实际电网和多种控制策略下发电机模式/电动机模式运行的双向储能设备组合而成。最后,基于Matlab/Simulink仿真平台验证DQFC分析方法的正确性和可行性。展开更多
The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the alu...The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the aluminum toxicity on pine seedlings, and the long-term soil acidification model(LTSAM) and a terrestrial biogeochemistry model(CENTURY) are used to simulate the influences of acid deposition on pine forest ecosystems. The indoor experiment results of aluminum toxicity show that aluminum ions in solution limit plant growth and acid deposition enhances this effect by facilitating the release of aluminum ions from the soil. Pine seedling biomass and root elongation decrease as the aluminum concentration increases. The results of model simulations show that the soil chemistry varies significantly with different changes in acid deposition. When the acid deposition increases, the pH value in the soil solution decreases and the soil Al^(3+) concentration increases. The increased acid deposition also has negative impacts on the forest ecosystem, i.e., decreases plant biomass, net primary productivity(NPP) and net CO_2 uptake. As a result, the soil organic carbon(SOC) decreases because of the limited supply of decomposition material. Thus acid deposition need be reduced to help protect the forest ecosystems.展开更多
文摘电网频率特性是电力系统运行机理分析和控制策略研究的基础,主要研究微电网中涉及双向储能设备的频率特性分析问题。首先,对变流器的功频特性和调频原理进行总结和分析。在此基础之上,针对传统频率特性分析法存在的参考值问题、单电源问题和单维度问题,提出双象限频率特性(dual quadrant frequency characteristic,DQFC)分析方法。该方法构建统一的功率参考体系,不但能实现传统分析方法的功能,而且可对双向储能设备和复杂多电源系统的一次调频、二次调频机理进行定性和定量分析。该多电源系统可由发电机组、无穷大电网、实际电网和多种控制策略下发电机模式/电动机模式运行的双向储能设备组合而成。最后,基于Matlab/Simulink仿真平台验证DQFC分析方法的正确性和可行性。
基金Under the auspices of National Basic Research Program of China(No.2010CB951802,2005CB422207)Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-219)National High Technology Research and Development Program of China(No.2009AA122104)
文摘The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the aluminum toxicity on pine seedlings, and the long-term soil acidification model(LTSAM) and a terrestrial biogeochemistry model(CENTURY) are used to simulate the influences of acid deposition on pine forest ecosystems. The indoor experiment results of aluminum toxicity show that aluminum ions in solution limit plant growth and acid deposition enhances this effect by facilitating the release of aluminum ions from the soil. Pine seedling biomass and root elongation decrease as the aluminum concentration increases. The results of model simulations show that the soil chemistry varies significantly with different changes in acid deposition. When the acid deposition increases, the pH value in the soil solution decreases and the soil Al^(3+) concentration increases. The increased acid deposition also has negative impacts on the forest ecosystem, i.e., decreases plant biomass, net primary productivity(NPP) and net CO_2 uptake. As a result, the soil organic carbon(SOC) decreases because of the limited supply of decomposition material. Thus acid deposition need be reduced to help protect the forest ecosystems.
