中文摘要：

针对小扰动长期电压稳定在线监测，建立了被监测节点局部区域节点功率传输等值模型，以及考虑局部区域以外系统影响的扩展的功率传输等值模型，并在此基础上将负荷裕度指标拓展到多机系统。根据被监测点相邻局部区域内的量测信息，计算节点功率传输等值模型参数，以其作为初值辨识出扩展的功率传输等值模型参数，进而计算节点局部指标，改善了弱可辨识性条件下的指标值精度，提高了基于局部指标的电压稳定在线监测方法的有效性。将提出的电压稳定在线监测方法在IEEE50机测试系统进行了仿真，参数辨识采用递推的带遗忘因子平方根最小二乘算法，结果表明它能有效地识别出电压稳定薄弱节点、实现电压稳定在线监测。

英文摘要：

Attention is focused on small-disturbance and long-term voltage stability monitoring. Both a single source power transmission equivalent model of the surrounding local power grids of the monitored node and an extended single source power transmission equivalent model taking the effects of the external grids into account are established. A load margin local index is applied to multi-machine power systems based on those established models. The information from the surrounding local power grids of the monitored node is used to calculate the parameters of the single source power transmission equivalent model, which is considered as the initial guesses to track parameters of the above extended single source power transmission equivalent model. The local index of node is calculated. The accuracy of the index is improved especially in the situation that the identifiable conditions are not met entirely. As a result, the validity of the method of on-line voltage stability monitoring based on local index is enhanced. In the IEEE 50 generators test system, the proposed on-line voltage stability monitoring method is tested, the recursive square-root least squares filter with a forget factor is applied to track the parameters, and the results indicate that it can identify the critical bus effectively so as to realize on-line voltage stability monitoring.