应用非线性等值原理解析计算电压稳定临界点

Voltage Stability Critical Point Analytical Algorithm Based on Nonlinear Equivalent Principle

连续潮流法是电力系统静态稳定分析的重要方法。当负荷增加到接近电压稳定临界点时,常规潮流方程计算难以收敛。选择合适的步长与鞍结分岔点快速计算是提高连续潮流计算效率的重要研究内容。研究了电力系统非线性等值泰勒级数参变量的选择方法:负荷静态阻抗模、电流模与电压模3个参数能够唯一确定电力系统的运行状态,都适合于作为描述系统运行状态的参变量。选择负荷阻抗模作为参变量,应用复合函数求导的链式法则,将电力系统功率参变量置换成分散的负荷等值阻抗模参变量,建立了节点电压与负荷电流的泰勒级数非线性等值模型。应用电力系统非线性等值模型,能够较大范围直接计算负荷极限功率与电压稳定临界电压,加快了电压稳域边界的计算速度。提出负荷电流与电压相互补偿原理以及终值边界条件,提高了泰勒级数对非线性等值模型的拟合精度。仿真结果表明:电力系统非线性等值泰勒级数在电压稳定鞍结分岔点是收敛的,非线性等值方法也能够精确地预测连续潮流计算的步长。

Continuation power flow method is an important method for power system static stability analysis. When the load increases to near the critical point of voltage stability, it is difficult for the regular power flow equations to converge. The research on how to choose the proper step-size and how to quickly calculate the saddle node bifurcation point play an important role on improving the continuation power flow calculation. The power system＇s non-linear equivalent Taylor series variable parameter selection method was presented in this paper. Three parameters of static load impedance mode, current mode and voltage mode can determine the state of power systems, which are suitable for describing the power system as variable parameters. By selecting load impedance mode as a reference variable, applying the chain rule derivative calculation, and displacing the power parameters into distributed load equivalent impedance mode parameters, the nonlinear equivalent model in Taylor series between node voltages and load current was established. The application of nonlinear equivalent model can directly calculate limit load power and the stability of critical voltage, and accelerate the calculation speed about the voltage stability boundaries. Load Current and voltage mutual compensation principle and the final boundary conditions were proposed, and the fitting precision of Taylor series for nonlinear equivalent mode was improved. Simulation results show that non-linear equivalent Taylor series is convergent in the saddle node bifurcation point; non-linear equivalent method can accurately predict the step in a continuous flow calculation.