Research on the optimization method for grid structures of the receiving-end power system with multi-infeed direct-current channels

In the receiving-end power system with multi-infeed direct-current channels, traditional direct-current(DC) power transmission channel needs to be supported by reactive power to maintain the normal operation. The larger the short-circuit capacity of the receiving-end system has, the stronger the supporting capacity from the receiving-end system will be with. But with the increment of system short-circuit capacity, bus short-circuit currents in the receiving-end system may exceed the breaking capacities of the breakers. There is the contradiction between the support capacity to DC transmission from the receiving-end system and increasing system short-circuit currents. In the multi-dc-infeed system, the simultaneous commutation failures of multiple DC channels need to absorb large amount of reactive power from the receiving-end system, leading to system voltage instability and other problems. Essence of the grid-structure optimization of the receiving-end system with multi-infeed DC channels is to solve the increasing short-circuit current problem on the premise to maintain the system stability and reliability. Based on the indices as effective short circuit ratio(ESCR), multi-infeed interaction factor(MIIF) and ac-dc voltage coupling factor(ADVCF), setting grid reliability, effects to block the chain reaction between DC channels and receiving-end system and system operation efficiency as the goal in this paper, the system structure optimization method is proposed, and effectiveness of the method is verified in Jiangsu provincial system.