Compared with the parallel mechanisms, the mobility analysis of the general multi-loop spatial mechanisms（GMSMs） is more difficult to obtain correct results. The reason is that its multi-loop is formed through sever...Compared with the parallel mechanisms, the mobility analysis of the general multi-loop spatial mechanisms（GMSMs） is more difficult to obtain correct results. The reason is that its multi-loop is formed through several times of closings and there also exists motion coupling even strong coupling, where the over-constraints are concealed. However, the mobility analysis for this kind of mechanisms has been paid few attentions. A new systemic methodology for analyzing mobility is proposed for GMSMs also based on the screw theory. The key issue for mobility analysis is to recognize the over-constraint. Firstly, three theorems are given and point out： the reason and site of over-constraint occurrence, calculating the number of over-constraints by the screw theory, and how to analyze the over-constraints for a single-loop mechanism as well. Then, three closing forms for GMSMs are proposed including rigid closure, movable closure and dynamic closure, and for the three different forms the different analysis methods are also given. Especially, for the most difficult issue of GMSMs with the multi-loop Closure in many times and the inevitable motion coupling, two important methods are proposed： ＂recognizing over-constraints by analyzing relative movement＂ and ＂recognizing over-constraints by virtual loop＂. The two methods are well used to solve the issue. Above-mentioned principles are not only systematic and effective but also unified. They provide a theoretical basis for the general multi-loop spatial mechanisms.展开更多
With the continuous development of urban distribution network, most of the distribution network has formed a dual power supply mode. The traditional way of distribution network load operating mainly adopts the power m...With the continuous development of urban distribution network, most of the distribution network has formed a dual power supply mode. The traditional way of distribution network load operating mainly adopts the power method, while satisfied the requirements of the safety of power grid, but will cause external short time power outages, poor user experience, realizing the distribution network outage rearrangement of load is a necessary means to improve power supply reliability. This paper presents mathematical model of load transfer in distribution network. The differences of voltage of amplitude and phase angle on both sides are calculated by the power flow. According to the differential pressure to determine whether the loop can be closed at the loop operation, thereby improving the success rate of operation.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51005195)Natural Science Research Fund for Youth in Higher Education Institutions of Hebei Province,China(Grant No.QN2014175)
文摘Compared with the parallel mechanisms, the mobility analysis of the general multi-loop spatial mechanisms（GMSMs） is more difficult to obtain correct results. The reason is that its multi-loop is formed through several times of closings and there also exists motion coupling even strong coupling, where the over-constraints are concealed. However, the mobility analysis for this kind of mechanisms has been paid few attentions. A new systemic methodology for analyzing mobility is proposed for GMSMs also based on the screw theory. The key issue for mobility analysis is to recognize the over-constraint. Firstly, three theorems are given and point out： the reason and site of over-constraint occurrence, calculating the number of over-constraints by the screw theory, and how to analyze the over-constraints for a single-loop mechanism as well. Then, three closing forms for GMSMs are proposed including rigid closure, movable closure and dynamic closure, and for the three different forms the different analysis methods are also given. Especially, for the most difficult issue of GMSMs with the multi-loop Closure in many times and the inevitable motion coupling, two important methods are proposed： ＂recognizing over-constraints by analyzing relative movement＂ and ＂recognizing over-constraints by virtual loop＂. The two methods are well used to solve the issue. Above-mentioned principles are not only systematic and effective but also unified. They provide a theoretical basis for the general multi-loop spatial mechanisms.
文摘With the continuous development of urban distribution network, most of the distribution network has formed a dual power supply mode. The traditional way of distribution network load operating mainly adopts the power method, while satisfied the requirements of the safety of power grid, but will cause external short time power outages, poor user experience, realizing the distribution network outage rearrangement of load is a necessary means to improve power supply reliability. This paper presents mathematical model of load transfer in distribution network. The differences of voltage of amplitude and phase angle on both sides are calculated by the power flow. According to the differential pressure to determine whether the loop can be closed at the loop operation, thereby improving the success rate of operation.
