The traditional synchronous power supply has been replaced by a large numbers of power electronic based grid-connected converters,resulting in insufficient reactive power margin of new energy power grid,reduced static voltage stability,and more and more obvious voltage instability or even collapse at the grid-connected point. Aiming at the above problems,the photovoltaic power generation system is used as an example in this paper to study the improvement of the static voltage stability of the system by using the new energy synchronous machine(motor-generator pair,MGP)grid-connected method. Firstly,the principle of MGP system is introduced and its power transmission characteristics are analyzed. Then,based on the V-Q and P-V curve methods that can reflect the relationship between node voltage and power flow,it is theoretically revealed that MGP can increase the reactive power margin to improve the static voltage stability. Finally,the electromagnetic transient simulation models of photovoltaic with load directly and via MGP were established respectively in the PDCSA/EMTDC software. By setting the load variation of different typical power factors with the similar system structure and combining with the V-Q/P-V response characteristics comparison,such typical indicators as unstable voltage,reactive power/voltage margin and voltage drop of the two systems are obtained. The results show that the static voltage stability of the original system can be significantly improved after the photovoltaic is integrated to the grid via MGP.
关键词
新能源电网/新能源同步机/V-Q曲线/P-V曲线/静态电压稳定
Key words
new energy grid/motor-generator pair/V-Q curve/P-V curve/static voltage stability
维普
万方数据