Global Suppression of DC Bias Based Optimal Configuration of Capacitor Blocking Devices

The capacitor blocking device (CBD) has a good effect on suppressing DC offset of a single transformer. However, incorrect configuration of CBDs will cause the bias current to shift, which will increase the bias current of other transformers in the regional grid. This paper proposes an improved multi-objective discrete particle swarm optimization algorithm (MODPSO) to optimize the configuration of the CBDs from a global perspective. First, analyze the flow path of the bias current in the AC power grid, and then build the earth-grid equivalent resistance model. Secondly, the mathematical model is constructed with the minimum number of the CBDs installed and the minimum sum of the transformer neutral current as the optimization objective. And the concept of adaptive inertia weight and particle mutation is introduced into the improved MODPSO, so as to find the Pareto optimal frontier of this problem. Finally, the correctness and superiority of the algorithm are verified through calculation examples, and the optimal configuration of the CBDs is determined accordingly.