Operation Risk Assessment of AC/DC Hybrid Distribution System Based on Two-Point Estimation Method

The operation risk assessment of AC/DC hybrid distribution system is of important to determine the operational status of the system and realize risk-based optimal scheduling. In this paper, a risk assessment method for AC/DC hybrid distribution network with fully consideration of VSC control modes is presented. In order to ensure the rapidity and accuracy of the assessment, a probabilistic power flow calculation based on two-point estimation method is proposed. The proposed two-point estimation method uses only two calculations of the deterministic power flow to calculate the statistical moments of the power flow solution, thus effectively reducing the calculation time of risk assessment. Finally, an AC/DC hybrid distribution network with three AC distribution areas and one DC network is employed to validate the proposed method. By comparing the results with Monte Carlo method, the validity of the model and method proposed in this paper is verified.