The main contribution of this paper is to propose an approach for monitoring and updating the load margin of power systems related to Saddle-Node Bifurcations (related to voltage instabilities) and Hopf Bifurcations (related to small-signal instabilities) considering variations in load growth directions of power systems. First, a set of load margins related to the bifurcations are calculated using a direct method considering uncertainties in the power system operating conditions and load growth directions. Then, a PMU placement formulation is proposed to select the buses that provide useful information about these load margins. The proposed monitoring system evaluates if the currently considered load growth direction gives a compatible voltage profile when compared to the one actually measured by the PMUs. If the profile is incompatible with the predicted one, the load growth direction is updated based on an optimization model. The proposed approach was applied and evaluated in the reduced south-southeast Brazilian system. Case studies showed that daily load profile curves showed different directions of load growth that resulted in load margins associated with different bifurcations. These results highlight the importance of correctly identifying and constantly updating the load growth direction and the load margin of power systems.

本文的主要贡献是提出一种方法，该方法考虑负载增长方向的变化，来监视和更新与鞍形节点分叉（与电压不稳定性有关）和霍普夫分叉（与小信号不稳定性有关）的电力系统的负载裕度电力系统。首先，考虑到电力系统运行条件和负荷增长方向的不确定性，使用直接方法计算与分叉有关的一组负荷裕度。然后，提出了PMU放置方式来选择提供有关这些负载裕量的有用信息的母线。当与PMU实际测量的电压比较时，建议的监视系统评估当前考虑的负载增长方向是否给出了兼容的电压曲线。如果该配置文件与预测的配置文件不兼容，则基于优化模型更新负载增长方向。所提议的方法已在巴西东南偏南地区的缩小系统中得到应用和评估。案例研究表明，每日负荷曲线显示了不同的负荷增长方向，从而导致了与不同分叉有关的负荷裕度。这些结果突出了正确识别和不断更新电力系统的负荷增长方向和负荷裕度的重要性。案例研究表明，每日负荷曲线显示了不同的负荷增长方向，从而导致了与不同分叉有关的负荷裕度。这些结果突出了正确识别和不断更新电力系统的负荷增长方向和负荷裕度的重要性。案例研究表明，每日负荷曲线显示了不同的负荷增长方向，从而导致了与不同分叉有关的负荷裕度。这些结果突出了正确识别和不断更新电力系统的负荷增长方向和负荷裕度的重要性。