Power flow calculation method for small impedance branch-containing power network employing compensation method and fast decomposition method

Abstract

The invention discloses a power flow calculation method for a small impedance branch-containing power network employing a compensation method and a fast decomposition method. Before power flow calculation, a small impedance branch is firstly processed and the small impedance branch is changed into a form of series connection of two branches, wherein the impedance of one branch is z1=r+j(x+xc), the impedance of the other branch is z2=-jxc, and xc is a mean value of reactance absolute values of the branches of which the reactance absolute values are smaller than a reactance threshold in a power system, and is called a normal reactance mean value of the power system. One small impedance branch is changed into two branches with relatively high impedance through series compensation, so that the convergence of power flow calculation can be improved. The small impedance branch with any impedance or even the branch with zero impedance can be calculated. According to the power flow calculation method, the problem of convergence due to the fact that a small impedance branch-containing branch system is analyzed by a conventional power flow calculation method employing the fast decomposition method can be effectively solved, and meanwhile, power flow calculation can be carried out on a normal system. Therefore, adverse effects are avoided.

Description

technical field [0001] The invention relates to a fast decomposition method power flow calculation method of an electric power system, in particular to a fast decomposition method power flow calculation method suitable for a small impedance branch system. Background technique [0002] Power system power flow calculation is a basic calculation for studying the steady-state operation of the power system. It determines the operating state of the power system according to the given operating conditions and network structure. The power flow calculation is also the basis of other analysis of the power system, such as safety analysis, transient stability analysis, etc., all use power flow calculation. Due to the advantages of reliable convergence, fast calculation speed and less memory requirements, the fast decomposition method has become one of the mainstream methods for power flow calculation. [0003] When there is no small impedance branch in the power system or the resistanc...

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Problems solved by technology

[0065] The method proposed in the Chinese patent ZL201410314990.6 effectively improves the convergence of the power flow calculation of the power system with small impedance branches, but when the resistance of the small impedance branches is large (r>>x), the method may still diverge

[0073] The methods proposed in Chinese patent ZL201410314990.6, Chinese patent ZL201510346974.X and Chinese patent 201610826604.0 all effectively improve the convergence of the power flow calculation of power systems with small impedance branches, but require the processing of small impedance branches to satisfy x>>r 2 , if this requirement is not met, the convergence becomes poor or even non-convergent

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