Under frequency load shedding Control Strategy Considering the Comprehensive Contribution Factor of Load Nodes

With the transformation of the energy system towards low-carbon, the high proportion of renewable energy and the low inertia characteristics of high proportion power electronic equipment pose serious challenges to the frequency safety of the power system. Under frequency load shedding (UFLS) is the third level protection measure to ensure the safe and stable operation of power system, which can effectively prevent the sharp drop of system frequency caused by power system failure. However, the traditional under frequency load shedding ignores the differences in the comprehensive characteristics of node loads, usually depends on the manually preset operating parameters, and lacks reasonable sorting principles and real-time flexibility as a whole. To solve the above problems, a under frequency load shedding strategy considering the new load shedding contribution factor of load nodes is proposed. Firstly, this study comprehensively considers the impact of load frequency regulation coefficient, transient voltage stability of nodes and load disturbance degree of different nodes on the overall effect of under frequency load shedding scheme. Secondly, the Delphi method (DM) and coefficient of variation (CVM) were used to determine the objective and subjective weights of load indicators, and the minimum discrimination principle information principle was used for comprehensive weighting to construct a new model of load reduction contribution factors for load nodes. This model was then applied to the selection of load reduction locations and the allocation of load reduction amounts. Finally, an example shows that the proposed improved under frequency load shedding strategy can improve the system frequency recovery level at the lowest frequency and the steady-state frequency under the same amount of load shedding, while restoring the system frequency as soon as possible, which fully verifies that the under frequency load shedding strategy taking into account the contribution factor has better performance.