转换效率是太阳能光伏并网逆变系统的关键技术问题。当前，多级式变换的拓扑结构多被系统采用，尽管其结构控制较为简单，但由于变换级数的增加，难于提高该结构的转换效率。因此，拥有高效低功耗、高可靠性、电路简单等诸多优点的单级式拓扑结构越来越成为太阳能光伏并网逆变系统设计的第一选择。随着现代数字信号处理技术以及电力电子技术的迅猛发展，克服系统拓扑结构带来的控制难题成为可能。

In the light of low precision of the turbine model used in power system simulation calculation,this paper analyzes the turbine and its pressurized water diversion system,simplifies and improves the model of the turbine and its pressurized water diversion system based on the power system simulation calculation,proposes the suggestions to select corresponding water hammer model according to the characteristic of the water diversion system.Simulation instance shows that improved model enhances simulation precision of the model,and can be used in the system simulation calculation.

According to the characteristics of the units and regulating system of the Laxiwa Hydropower Station,and in consideration of the power counter-adjustment in hydro-units primary frequency modulation process,the primary frequency modulation parameters are optimized according to the primary frequency modulation technology requirements of electric power dispatching institution. The poor matching between primary frequency modulation and AGC (secondary frequency modulation) is improved and optimized; thus,both primary frequency modulation and AGC can play their normal functions.