| Summary: | Aiming at the problem of frequency stability of the asynchronous AC/DC hybrid power grid, a prediction model of post-disturbance steady frequency is proposed, which considers the emergency DC power support (EDCPS) and the frequency response of AC grids on both sides of the high-voltage DC (HVDC) link. This post-disturbance steady frequency of both AC grids can be predicted quickly by utilising the wide area measurement system data, and the desired amount of EDCPS can be calculated directly by using the setting value of the steady frequency for the disturbed AC grid. Then this study considers the fact that the voltage level of the AC buses at both ends of the HVDC system will affect the operation modes of the HVDC system, resulting in the limited EDCPS. Therefore, a calculation method of the actual EDCPS command for steady frequency control is proposed. It can automatically identify the actual operation mode of the post-disturbance HVDC system and calculate the actual EDCPS command corresponding to the desired EDCPS value. Simulations of a typical two-area AC/DC hybrid power grid are carried out to validate the effectiveness of the proposed method.
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