适用于潮流分析的改进网络等值建模方法研究

Research on Improved Network Equivalent Modeling Method for Power Flow Analysis

Ward等值法作为一种重要的等值建模方法,在电力系统分析计算中得到广泛应用。实际应用Ward等值时会出现2个问题:一是求解等值方程时如何提取电网数据计算等值导纳矩阵和等值电源;二是等值误差问题,包括等值过程中产生的误差以及系统运行状态改变时产生的误差。为此提出一种适用于潮流分析的改进等值建模方法,针对等值方程求解中存在数据提取问题,提出一种基于PSCAD中的PSD-SCCP短路故障分析功能求解等值电源和导纳矩阵的方法,实现在PSCAD中对大电网建模;针对常规等值在系统工况发生变化时的误差问题,研究一种用电压源串联阻抗的形式建模修正误差的办法,使等值系统潮流发生变化时与完整系统的PV节点发生相同响应,通过算例验证了方法的有效性。

As an important equivalent modeling method,ward equivalent method has been widely used in power system analysis and calculation.There are two problems in the practical application of Ward equivalent method.One is how to extract grid data to calculate equivalent admittance matrix and equivalent power supply when solving the equivalent equation,the other is the equivalent error problem,including the error caused by the equivalent process and the errors caused by changes of the system operation state.Therefore,this paper proposes an improved equivalent modeling method suitable for power flow analysis.Aiming at the problem of data extraction in the solution of equivalent equation,it also proposes a method of solving equivalent power supply and admittance matrix based on the short-circuit fault analysis function of PSD-SCCP to realize the modeling of large power grid in PSCAD.In view of the problem of conventional equivalent error,the paper studies a method to correct the equivalent power supply and the acceptance matrix by using the form of the parallel impedance of the voltage source as the equivalent machine modeling error,so that the equivalent system will have the same response as the PV node of the complete system when the power flow changes.The effectiveness of the method is verified by a numerical example.