Coordinated control method for mutiple high-voltage direct current (hvdc) links after fault based on extended equal area criterion

A coordinated control method for multiple high-voltage direct current (HVDC) links after a fault based on an Extended Equal Area Criterion, comprising the following steps:

• S1:
• acquiring monitored angular velocity data of all generators in a sending-end system after the fault, and dividing a critical generator group GS and a remaining generator group GA according to the monitored angular velocity data;
• S2:
• calculating a support effect evaluation index of each DC converter station for all generators in the critical generator group GS to determine a DC converter station with an optimal support effect as an optimal DC converter station;
• S3:
• if a fault type is a three-phase short-circuit fault, reducing a power of the optimal DC converter station by f percentage points;
• and if the fault type is a DC fault, increasing the power of the optimal DC converter station by f percentage points;
• S4:
• considering a dynamic process of the system and a variation in relative magnitudes of an equivalent angular velocity of the critical generator group GS and an equivalent angular velocity of the remaining generator group GA in the dynamic process, i.e., re-determining the optimal DC converter station if a sign of a difference between the two equivalent angular velocities switches, wherein if the equivalent angular velocity of the critical generator group GS is greater than the equivalent angular velocity of the remaining generator group GA, a DC power of a present optimal DC converter station is increased by f percentage points, and otherwise, the DC power of the present optimal DC converter station is reduced by f percentage points;
• and
• S5:
• repeating the steps S1 to S4 until a total time of all the DC power increases and reductions reaches a short-time overload time limit ts of a converter station.