Abstract:
Reasonably evaluating the multi-feed-in DC carrying scale of the receiving grid is of great significance in guiding grid construction and maintaining grid security and stability. Considering the influence of DC impact point, unit output distribution and reactive power compensation on the DC bearing capacity of receiving end power grid, the generalized effective short-circuit ratio to quantify the strength of node voltage support to the DC feed-in is analyzed. Next, the model for implementing the combined optimization of both the DC drop point and the generator output distribution is established based on using the generalized effective short-circuit ratio index, transient voltage support strength index, network loss index and cost index of generator, and the multiple constraints considering the safe operation of the receiving grid. Then, the method for accessing the maximum DC load-carrying capacity of the receiving grid based on multi-objective optimization is proposed, which acquires the result of the maximum DC load-carrying capacity by using the cyclic incremental DC feed-in capacity and the repetitive solution optimization model to obtain the optimized solution set that satisfies the constraint conditions, as well as the safety check of the solution set in reverse order. On this basis, the method to increase the maximum DC load-carrying capacity based on multi-objective optimized reactive power compensation is further proposed. Finally, the IEEE 39-node system and Henan province planning power grid are used as a multi-fed DC receiving grid for simulation analysis, which verifies the feasibility and validity of the proposed method for analyzing the maximum DC load-carrying capacity of the receiving grid.