From the perspective of senior citizens,questionnaire survey and field investigation were carried on and analyzed in three parks in Nanjing City.The results showed that outdoor activities are the principal ways for th...From the perspective of senior citizens,questionnaire survey and field investigation were carried on and analyzed in three parks in Nanjing City.The results showed that outdoor activities are the principal ways for the senior citizens to spend their time,the parks near home is their prior choice,and the radiation range of the park and greenbelt mostly is no more than 2 km;most of the senior citizens come to parks on foot and the parks are always within 30 minutes walking distance;the senior citizens always have fixed partners and groups for their exercise-dominant activities.展开更多
文摘From the perspective of senior citizens,questionnaire survey and field investigation were carried on and analyzed in three parks in Nanjing City.The results showed that outdoor activities are the principal ways for the senior citizens to spend their time,the parks near home is their prior choice,and the radiation range of the park and greenbelt mostly is no more than 2 km;most of the senior citizens come to parks on foot and the parks are always within 30 minutes walking distance;the senior citizens always have fixed partners and groups for their exercise-dominant activities.
文摘多微源独立微网中,传统下垂控制的输出频率动态响应速度快,虚拟同步发电机(virtual synchronous generator,VSG)控制可改善频率响应特性,但无法兼顾功率和频率的动态调节性能。针对此问题,提出一种改进的转动惯量自适应控制(improved adaptive control of inertia,IACI)。首先,在同步旋转坐标系下建立VSG数学模型,并分析转动惯量对VSG输出特性的影响;其次,在VSG控制的基础上通过在转动惯量控制中引入频率变化量形成VSG转动惯量自适应控制,并给出频率跟踪系数、转动惯量和阻尼系数等参量的整定方法;最后利用Matlab/Simulink对比VSG控制和IACI控制在VSG并入微网和负载扰动条件下的有功和频率响应曲线,在由两台1k W的VSG组成的独立微网实验平台上进行实验验证,结果表明所提控制策略可避免VSG并入微网过程中的有功振荡,且可以有效优化频率响应曲线。
