The energy storage doubly-fed condenser with high inertia and wide slip variable speed operation ability can provide more effective rotor energy storage than traditional synchronous condenser

and has obvious advantages in frequency support. However

it is difficult for the existing inertia control method to achieve the ideal frequency support effect because it fails to consider the frequency modulation effect of other units in the system

as well as to take into account the steady-state constant speed operation requirements. Therefore

a rotor speed control strategy of energy storage doubly-fed condenser for system frequency trajectory optimization is proposed. Using the frequency response model of the grid-connected system

the frequency trajectory optimization control transfer function is constructed for the two indexes of maximum rate of change of frequency and maximum frequency deviation. Then

the analytical formula of the rotor speed command under the control form is derived

the frequency support mechanism of different links is analyzed

and the calculation method of main parameters is provided

so as to design the actual rotor speed control system. Finally

the feasibility and effectiveness of the strategy are verified in the simulation system with a new energy station.