静态电压稳定性的临界特性和最小稳定裕度的确定

恒功率因数负荷PR-VR曲线和临界恒功率负荷PR.cr-QR.cr曲线已广泛应用于电压静态稳定性分析中。文中针对π型电路求出了用A、B、C、D参数表示的恒功率负荷的临界点特性，如负荷临界电压(幅值和相角)，负荷临界阻抗和临界功率；证明了PR.cr-QR.cr曲线是抛物线，指出maxPR.cr/maxQR.cr只与参数A、B有关，并分别讨论了PR.cr-VR.cr曲线与PR-VR曲线和PR.cr-QR.cr曲线的关系；在PR-VR和PR-QR平面上分别讨论了由奇异点族构成的奇异曲线间及对应的可运行稳定域间的一一对应关系；提出了求取在PR-QR平面上与工作点最近的奇异点的解法，并在简单系统和IEEE 30系统上进行了验证。

Critical Characteristics of Steady-state Voltage Stability and Determination of Minimum Stability Margin

Constant power factor PR-VR curve and critical constant power PR.cr-QR.cr curve are widely applied in voltage stability analysis. In this paper, firstly, the characteristics of critical point are expressed with ABCD parameters for constant power load in π type circuit, these characteristics include critical voltage(amplitude and angle), critical load impedance and critical power, etc. Secondly, the PR.cr-QR.cr curve is proved to be a parabola, maxPR.cr/maxQR.cr is determined by parameters A and B only, and the relations between PR-VR curve and PR.cr-VR.cr curve, between PR.cr-VR.cr curve and PR.cr-QR.cr curve are pointed individually. Thirdly, the one-to-one correspon- dence between singular curves on PR-VR and PR-QR planes formed by a family of singular points are described together, so do the corresponding operable stability domains. At last, the solution of the nearest point on the singular curve from the operating point is given and was verified on a simple system and IEEE 30 system.