Method for calculating load flow of power grid alternating current and direct current power transmission system based on state switching

Abstract

The invention discloses a method for calculating the load flow of a power grid alternating current and direct current power transmission system based on direct current system control logic, and belongs to the technical field of power grid alternating current and direct current power transmission. The method is characterized by including the steps: (1) acquiring steady-state operation parameters needed for calculating the load flow of the alternating current and direct current power transmission system; (2) building direct current control logic in load flow calculation; (3) determining a direct current power transmission system control mode according to the operation state of the system and the direct current control logic; (4) calculating the load flow of the alternating current and direct current power transmission system in the determined direct current control mode; (5) drawing a calculation conclusion if calculation finishing conditions are met; and (6) switching to the step (3) if the calculation finishing conditions are not met, and continuing to perform calculation. By the method, the load flow of the alternating current and direct current power transmission system can be more effectively and reliably calculated, and a basis is provided for planning and operating the alternating current and direct current power transmission system according the control mode and the switching process of the direct current power transmission system.

Description

technical field [0001] The invention relates to a power flow calculation method for a power grid AC-DC hybrid transmission system, in particular to a state conversion-based power flow calculation method for a power grid AC-DC transmission system, and belongs to the technical field of power grid AC-DC power transmission. Background technique [0002] HVDC is more and more widely used in power system. The DC transmission system has a high degree of controllability and flexible control methods, so the control function of the DC system must be considered in the power flow calculation process of the AC-DC hybrid transmission system. [0003] The power flow calculation of the traditional AC / DC hybrid system is carried out under the single control mode of the DC transmission system. It can be divided into two categories: unified iteration method and alternate iteration method. [1] . The unified iterative method considers the coupling relationship between AC and DC variables, and...

AI Technical Summary

Problems solved by technology

This calculation strategy has the following disadvantages: First, the convergence is poor, and the calculation reliability is greatly reduced

Due to the constant replacement of variables in the iterative process of power flow calculation, in some cases, the power flow calculation will oscillate and fail to converge; the second is that the control method considered is simple and not comprehensive; it is limited by the reliability of the calculation , the DC control method is considered too simplified, and the accuracy of the calculation is reduced; the third is that in the calculation of a power flow, DC control changes and transformer tap control and other issues must be considered, and the programming is complicated, which is not conducive to the commercialization of the algorithm.

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