PMU-Based Evaluation of Transmission Bus Strength through Angle Sensitivity Metrics

As the share of wind power generation increases, the power system stability may be adversely affected. Wind interconnection studies are conducted to evaluate and anticipate the interactions between the wind project and the power system. Various metrics have been developed to evaluate the system strength at the point of interconnection: short-circuit ratio, voltage stability limit, and system inertia. These metrics, unfortunately, rely on network data which may not be readily available. In this paper, a voltage phase angle based index is proposed for evaluating a transmission bus strength. The proposed metric describes the sensitivity of the change of voltage phase angle to the change of active power flow. The proposed metric requires no network information but solely rely on PMU measurements. The validity of the proposed metric is demonstrated by applying it to analyzing the system strength of the Panhandle region of the ERCOT transmission network. Through field data, it is shown that the proposed metric correctly identifies buses as strong or weak. Moreover, the metric can determine the system strength caused by varying wind power production. It is shown that the system strength decreases during high wind power generation, and vice versa.