Optimized Installation Strategy Of Transformer DC Bias Blocking Devices In Regional Power Grid

In recent years,the phenomenon of DC bias in substations caused by the monopole operation mode of HVDC transmission is increasing.Commonly used treatment measures are the resistance method,the capacitance method,and the reverse injection current method.Considering the high installation and operation cost of the blocking device and the difficulty of substation transformation,it is impossible to install the straightening device in all substations around the DC grounding electrode,and the optimal configuration scheme of the existing treatment device fails to consider the fault condition of the straightening device.Therefore,the lack of relevant research is targeted.This paper aims at the phenomenon of DC bias and its treatment,and main contents are as follows:Firstly,this paper establishes a field-circuit indirect coupling model for DC bias current calculation,and on this basis,the advantages and disadvantages of capacitance method and resistance method on DC bias treatment of power grid are studied,and the necessity of DC bias treatment of regional power grids from the overall perspective is demonstrated by analyzing the change DC distribution in the power grid during single-station governance.Then,this paper proposes an installation strategy of DC bias blocking device of transformer based on the heuristic algorithm,which can comprehensively consider the cost and treatment effect.the installation strategy optimization model is established with the installation and maintenance cost and the weighting of the neutral point current value of the transformer as the optimization objective function,and then that at all transformer neutral points is not exceeded as the constraint condition,and finally,the particle swarm algorithm and the genetic algorithm are used to obtain the optimal installation strategy.Finally,to verify the effectiveness of the proposed installation strategy,the actual parameter model of Jinhua Power Grid is constructed,this paper considers the parameters such as the comprehensive cost and importance level of multiple substations,and analyzes the significance represented by the difference in the weights of cost and importance level.By optimizing the objective function and constraints of the installation strategy,it is ensured that the configuration scheme meets the overall substation DC current limit when a single DC blocking device failure occurs in Jinhua Power Grid.The results show that the installation strategy of the DC bias blocking device proposed in this paper can quickly and effectively obtain the optimal configuration scheme of the DC blocking device of each substation in the regional power grid.