计及负荷电压静态特性的电力系统最小负荷裕度的快速评估

摘要

Load margin is one of the most important index in static voltage stability, minimum load margin of nonlinear complex variable power system is defined. Power parameter is introduced using a dynamic equivalence method of nonlinear circuits, Lagrange function is constructed. It is proved the necessary condition of the maximum active power of nonlinear electric power network load node is that load static equivalent impedance mode is equal to dynamic equivalent impedance mode of load node, impedance modulus margin index is put forward which is used for assessing voltage stability. Under the same disturbance, the smaller the impedance module margin is, the weaker the voltage stability is, so the smaller the node load margin is. Therefore, the biggest load margin of the weakest node is calculated, it is minimum load margin. When impedance model margin of the weakest load node is zero, maximum active power is obtained and maximum load margin is calculated. Through simulation on IEEE30 nodes system under different disturbance ways considering load voltage static characteristic, it indicates that single node disturbance way and the increase of constant impedance and constant current load ratio improve minimum load margin of power system.%负荷裕度是静态电压稳定性最重要指标之一，定义了非线性复变电力系统的最小负荷裕度。利用非线性电路动态等值方法，引入功率参变量，构造拉格朗日函数。证明非线性电力网络负荷节点获取极大有功功率的必要条件：负荷静态等值阻抗模等于负荷节点看进系统的动态等值阻抗模，然后提出评估电压稳定性的阻抗模裕度指标。同一扰动下，阻抗模裕度越小，电压稳定性越薄弱，节点负荷裕度越小，只需计算最薄弱节点的最大负荷裕度，即系统最小负荷裕度。通过阻抗模裕度最先到达零来确定最薄弱节点获取的极大有功功率，计算其最大负荷裕度。计及负荷功率扰动方式与负荷电压静态特性，通过对 IEEE30节点系统的仿真表明：单节点负荷功率扰动方式及恒定阻抗与恒定电流负荷比例的增加，提高了系统的最小负荷裕度。