The traditional synchronous power supply has been replaced by a large numbers of power electronic based grid-connected converters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.