Dynamic reactive power compensation is an effective means to improve the safe and stable operation of power grid. In the current UHV AC/DC grid

the stability of the receiving end power grid interacts with the DC transmission systems. The use of dynamic dynamic reactive power compensation can increase the strength of the receiving end system and improve stability of voltage and frequency. It is therefore important to study the capability of various dynamic reactive power compensation devices to understand the stability of large power grids. In this paper

the functions of such three typical dynamic reactive power compensation devices as synchronous capacitor（SC）

static var compensator（SVC）and static synchronous compensator（STATCOM）systematically introduced and discussed. Through the combination of analytical deduction and digital simulation

the performance of these compensation devices is reviewed in detail.The conclusion in this paper can be used for the customers to design and choose the appropriate dynamic reactive power compensation devices and provide effective means to ensure the stable operation of power grid.