Risk Assessment of Node Voltage Sag under the Scenario of DG Connected to Grid

Scientific assessment of the voltage sag risk level at each node of the power grid is the prerequisite for voltage sag management. In view of the lack of consideration of the low voltage ride through characteristics of distribution generator (DG) and power grid topology in the existing methods, this paper proposes a node voltage sag risk assessment method under the grid connection scenario of DG. Firstly, a fast and accurate solution method based on Fibonacci method is proposed for the exposed area. Then, the exposed area overlap index, DG isolation risk index and connectivity index of nodes are proposed respectively. Based on Entropy TOPSIS method and expert experience, the objective and subjective evaluation indexes of node voltage sag risk are obtained respectively. Combined with subjective and objective indexes, a comprehensive evaluation method of node voltage sag risk is constructed. Finally, based on the Monte-Carlo principle, the IEEE 30-nodes system is simulated to verify the rationality of the proposed comprehensive assessment method of voltage sag risk.