Research On Improving Reclosing Rate Of Rural Small Hydro-plant Plant Synchronizing Major Grid

Small hydropower is internationally recognized clean and renewable energy, which can be developed dispersedly, on-site into nets, nearby electricity supply and with other advantages, it can be generally built in remote mountainous area, so the development of small hydropower can improve rural energy structure and fully adaptive to preferential policies related renewable energy. After decades of development and construction, the construction of the small hydropower development in our country have also made great achievements, small hydropower has become an important part of the power industry.For the small hydropower lack of rapid and effective signal channel, it cannot adjust power quickly, which makes it an independent power supply of the island after the grid single traverse or big power grid disconnect because of breakdown tripped and the island may cause unusual frequency and voltage upheaval due to power imbalance and leads to the failure of isolated land reclosing. Based on this issue, this paper launched a series of research.This paper briefly introduces some basic properties of the small hydropower and the development and future prospects of small hydropower in China. The paper also expounds the basic principle of automatic reclosing from the aspects of the best reclose time, the best reclose capture moments and adaptive reclose outlined his situation. This paper aims at the features of the small grid, such as lack of fast and effective signal channel, protection movement delaying, establishes and its mathematical model, which present the specific analysis method of the calculation of limiting time. Then it introduces the method of generator over-speed cutting, when the connecting line failures and the system arises leavings which can effectively control the ascending of frequency by reasonable cutter and making the system stable. And in Hunan Province, the actual situation of small hydropower systems simulation results show that the coordination of the generator over-speed cutting proposed by this paper and the rapid capture inspection period reclose device can meet the reclosing action time requirements, which greatly improves the success rate of rural water power grid fault reclosing and it has the universal engineering meaning for the small hydropower projects.