When the DC blocking fault occurs in the UHVDC of AC/DC hybrid system

the hybrid AC/DC receiving-end power grid may produce a huge power shortage

cause a significant power transfer and frequency drop

cause the AC channel overload

and even lead to chain failure. In order to solve this problem

a calculation method of optimal load shedding scheme is presented for hybrid AC/DC receiving-end power grid based on the wide-area measurement system(WAMS). The estimation model of AC channel transmission power and the frequency is established by using the instantaneous measurement data after DC blocking. Considering the AC channel transmission power limit

the grid frequency safety constraints

and the different importance of each load

the optimization model of the optimal load shedding is established with the objective of minimizing the total load shedding. Through the improved particle swarm optimization(PSO)algorithm

the optimal load shedding amount of each load is solved

which ensures the safe and stable operation of the hybrid AC/DC receiving-end power grid after the DC blocking. The improved IEEE 39-bus system is taken as an example in the PSS/E software. Simulations and analysis are carried out to validate the effectiveness and accuracy of the proposed method.