Transmission network-distribution network joint fault analysis method based on improved node method

Abstract

The invention relates to a transmission network-distribution network joint fault analysis method based on an improved node method. The fault analysis method comprises the steps that 1) electrical parameters of a transmission device are acquired, and electrical parameters and control parameters of direct current transmission, a direct current power supply and a distributed power supply are acquired; (2) a coordination transmission network-distribution network is decomposed; (3) a phase sequence hybrid network is established; (4) a disconnection line of a vertical fault line is replaced by a constant current source branch with the current of 0, and a constant voltage branch with the voltage of 0 is added to a short circuit node of a crosswise fault line; (5) a transmission network and a distribution network are respectively modeled, and current and voltage electrical parameters of a failed network are calculated; and (6) a node voltage error is calculated, and if the error is greater than 10-8.p.u., returning to step (5) is carried out for recalculating. According to the technical scheme of the invention, by studying the mutual influence of the fault calculation of the transmission and distribution network, a phase sequence hybrid circuit is processed; and non-linear characteristics under various faults are analyzed.

Description

technical field [0001] The invention relates to the field of power system fault analysis, and more specifically relates to a transmission network-distribution network joint fault analysis method based on an improved node method. Background technique [0002] With the continuous penetration of DC transmission, electric vehicles and distributed power into the transmission-distribution network, the fault calculation of the distribution network is more complicated, and the setting of the relay protection of the distribution network is more difficult. In the past, in the fault calculation of transmission-distribution joint, the transmission network is equivalent to the distribution network side by using Thevenin equivalent, and the fault calculation is only performed on the distribution network. With the connection of nonlinear power electronic equipment such as DC transmission to the transmission network, it is difficult to describe the electrical characteristics of the transmis...

AI Technical Summary

Problems solved by technology

When these methods are used to accurately calculate the fault current of the distribution network, there are the following problems: when the compensation method is used for fault calculation, the short-circuit fault is modeled as adding a branch with a resistance of 0, and the open-circuit fault is modeled as adding a value at the fault point If the resistance is very large, the model cannot perform iterative calculations, and cannot calculate and deal with nonlinear fault characteristics such as arc resistance and distributed power sources. Sequence network analysis is suitable for the calculation of symmetrical three-phase structural parameters of the power grid. For three-phase structural parameters that are not Symmetrical distribution network, the computational efficiency of sequence network analysis is reduced

[0004] A unified calculation method for power flow faults in distribution networks has been proposed ([1] Wu Wenchuan, Zhang Boming. A unified analysis method for power flow faults in three-phase unbalanced distribution networks [J]. Electric Power System Automation, 2002, 20 (20): 50– 54. [2] Zhang Xiaoping, Chen Heng. A unified analysis method for power flow and faults in asymmetrical three-phase power systems [J]. Electric Power System Automation, 1994,18(8):18–24.), although iterative calculations can be realized, However, its essence is a process of alternating and iterative power flow-fault calculations, which is not a strict unified calculation method for power flow faults in the distribution network, nor does it consider the influence of the transmission network on the fault current calculation of the distribution network.

[0005] And because the transmission and distribution network may be managed by different companies, it is difficult to centralize the data of the transmission and distribution network for fault calculation, so it is necessary to propose a fault calculation method for the decomposition and coordination of the transmission-distribution network

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