Measurement-Based Transmission Capability Estimation of Power Grid Using Load Response-Based Equivalent Model

In this paper, the load response-based equivalent model is proposed to develop a more sturdy method for the transmission capability estimation of the power grid. Based on real-time phasor measurement unit (PMU) measurements, the power grid is modelled as the multi-port equivalent model based on the coupled single-port models. The associated critical equivalent branch in the multi-port model is identified and modified by the shaping factor to construct the proposed model. According to the modification, the dissimilarity of the load response index between the critical equivalent branch and the approximate profile of the actual load voltage can indeed be reduced to obtain the perfect matching between the critical load voltage and the actual load voltage. Accordingly, the accurate and sturdy transmission capability estimation can be achieved in the proposed model. Moreover, the proposed model is further extended to design a complete solution algorithm for the limit-induced transmission capability estimation considering generator reactive power limits. Simulations on IEEE 14-bus and IEEE 118-bus test systems are presented to validate the accuracy and the sturdiness of the proposed method.