2 results about "Wave processes" patented technology

The application discloses a kind of flexible direct current transmission line fault transient electrical quantity determination methods, comprising: according to the circuit parameter of MMC converter station, construct MMC equivalent circuit when inter-pole short circuit;According to the transmission line parameter obtained, establish the equivalent model of two-port of direct current transmission line under complex frequency domain;According to the equivalent circuit of MMC when inter-pole short circuit and the equivalent model of two-port of direct current transmission line, obtain the expression of direct current fault transient under complex frequency domain;The expression of direct current fault transient under complex frequency domain is carried out Laplace transformation to obtain time domain response, the whole trend of transient process after fault can be given more accurately by the application.The calculation process is simple, avoids the complicated modeling simulation process in traditional simulation method.Meanwhile, it can well reflect the occurrence wave process when overhead line fails.The method can accurately express the overall development trend of the fault current flowing through the protection installation before the converter station is locked after the fault occurs, and has a positive significance for the fault current suppression and protection setting design of MMC-HVDC system.

The application provides a wave process calculation method considering the corrugated aluminum sheath structure of a high-voltage cable, and the steps include: deducing the inner radius formula of the corrugated aluminum sheath of the high-voltage cable according to the geometric characteristics of the corrugated aluminum sheath; using the average geometric radius technology to equivalently convert the corrugated aluminum sheath into a uniform cylindrical shell; using a sine function to fit the corrugation of the actual corrugated aluminum sheath; solving the effective length of the equivalent uniform cylindrical shell; deducing the conductor impedance calculation approximate formula based on the effective length and the equivalent uniform cylindrical shell structure; deducing the admittance calculation formula based on the actual corrugated aluminum sheath structure of the high-voltage cable; calculating the cable wave transmission process characteristic parameters considering the corrugated aluminum sheath structure based on the above formula; and verifying the calculation results by building a low-voltage pulse verification test loop. The application is not only suitable for the distributed parameter equivalent circuit calculation of the corrugated aluminum sheath power cable of different sizes, voltage grades and lengths, but also can improve the electromagnetic transient simulation accuracy of the cable.