Multi-DC-feed (multi-direct current-feed) AC (alternate current) grid fault calculating method taking DC control characteristics into consideration

Abstract

The invention discloses a multi-DC-feed AC grid fault calculating method taking DC control characteristics into consideration. The multi-DC-feed AC grid fault calculating method comprises the following steps of inputting system parameters, DC control strategies and fault parameters of an MODC (multi-outfeed direct current) system; forming an AC system sequence network chart through the system parameters and the fault parameters of an AC grid, establishing an AC constraint equation, and establishing a DC constraint equation between the DC voltage and the DC current of a DC side through the DC control characteristics; setting initial values for all variables; establishing converter switch function models SI and SU of every DC subsystem; according to the AC constraint equation, the DC constraint equation and voltage and current switch functions, solving the transient state parameters of the AC side and the DC side of the MODC system; performing iterative computation, and when variable errors meet computational requirements, outputting the computation results of the transient state parameters of the AC side and the DC side of the MODC system. The multi-DC-feed AC grid fault calculating method taking the DC control characteristics into consideration is high in computation speed, accuracy and adaptability and has high engineering practical value in the aspect of setting and cooperation of fault computation and relay protection of multi-DC-outfeed AC grids.

Description

technical field [0001] The invention relates to the research field of a fault calculation method of a power system, in particular to a fault calculation method of a multi-DC feed-in AC power grid considering DC control characteristics. Background technique [0002] Compared with AC transmission, DC transmission has many advantages in terms of long-distance and large-capacity transmission, and is widely used in the transmission system that transmits electric energy from western regions with abundant power resources to eastern coastal regions. With the continuous expansion of electricity demand, it will also be possible to draw multiple DC transmission systems from the AC power grid in the western region with abundant power resources to form a multi-DC feed-in power transmission system. Following the Ningdong HVDC transmission project, Ningxia's second HVDC transmission project, the Ningdong-Zhejiang UHVDC transmission project, is scheduled to be completed and put into operati...

AI Technical Summary

Problems solved by technology

However, there is still a lack of effective calculation methods for the fault calculation of AC power grids with multi-circuit DC system feed-out. Although the detailed electromagnetic transient simulation method can simulate the fault transient process of the MODC network in detail, and in the case of multi-circuit DC systems In this case, the electromagnetic transient simulation model is relatively complex, and the simulation calculation time is extremely long, which is difficult to apply to occasions with high requirements for calculation rate. Therefore, it is necessary to propose a new method to improve the calculation rate on the basis of ensuring calculation accuracy.

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