电力系统电压稳定监视与控制需要准确模拟负荷的电压响应特性。负荷在故障后的动态恢复特性是中长期电压失稳或电压崩溃的直接原因。该文提出一种模拟负荷动态恢复特性的连续潮流模型,将负荷功率的时域恢复特性等效转化为负荷静态电压模型中系数的连续变化。文中分别给出ZIP多项式和幂函数2种负荷模型的系数参数化方法,并推导和给出稳定临界点的灵敏度计算公式。负荷恢复型连续潮流可作为一种新的电压失稳故障识别方法。应用该模型在IEEE118节点系统,结果表明负荷恢复型连续潮流可模拟故障后负荷功率的动态恢复过程,识别失稳故障并给出可供预防控制用的灵敏度信息。
It is necessary to simulate the voltage response characteristics accurately of load in voltage stability assessment and for control of power system. The post-contingency load dynamic restoration is one of the direct reasons leading to mid-long term voltage instability or voltage collapse. A novel continuation power flow (CPF) model for simulating the load dynamic restoration in time-domain is proposed in this paper. The load restoration process is transformed equivalently into the continuous variation of parameters in static load voltage model, The homotopy parameterization methods based on both the ZIP polynomial load model and the exponential load model are given. The sensitivity formulation of the continuation parameter with respect to any control at the critical points is presented. The proposed CPF model can be taken as a new method for identifying the voltage unstable contingencies. The numerical results with IEEEll8 bus test system show that the proposed model and method is effective in simulating the load restoration characteristic in time-domain, unstable contingency identification and the sensitivities for preventive control.