Hybrid sub-modular mmc converter with DC fault ride-through capability

Abstract

The invention relates to a hybrid sub-module MMC converter with DC fault ride-through capability. The hybrid sub-module MMC topology is similar to the half-bridge MMC, which is still a three-phase six-leg structure, but a single bridge arm consists of m half-bridge sub-modules (HBSM), n full-bridge sub-modules (FBSM) and l Two clamping dual sub-modules (CDSM) are cascaded in sequence; combined with the high DC voltage utilization rate of FBSM, the DC fault current self-clearing shared by FBSM and CDSM, and the economical advantages of HBSM, according to actual needs, m, n and l Optimizing the selection of the number of the converter can make the converter applicable to the flexible DC transmission system, especially in the occasions where the operation rate of the system is required to be high when the DC fault occurs, so that it can improve the system while having the DC fault ride-through capability. Capacity, saving economic cost.

Description

technical field [0001] The invention relates to the technical fields of flexible direct current transmission and distribution of power systems, power electronics and user electric power, and specifically relates to a flexible direct current transmission MMC converter valve topology with direct current fault ride-through capability. Background technique [0002] DC short-circuit fault is the most common fault in the MMC-HVDC system. Traditional MMC converters based on half-bridge sub-modules cannot cut off the feed from the AC system to the DC short-circuit point by blocking the sub-module IGBT in the event of a DC bipolar short-circuit fault. If there is a power circuit, the AC circuit breaker or DC isolating switch must be quickly tripped to clear the fault current, which not only increases the system cost, improves the technical requirements for the equipment, but also reduces the system operation rate and slows down the fault recovery speed. [0003] At present, most proj...

AI Technical Summary

Problems solved by technology

The former has a complex structure and high difficulty in control, which is not conducive to project implementation

In the latter, in addition to the DC fault ride-through capability, the full-bridge sub-module MMC can also improve the DC voltage utilization rate due to the negative voltage characteristics of the module, thereby increasing the system capacity; the clamped twin-sub-module MMC has less power than the full-bridge sub-module. The number of components is more economical, but it is still at a disadvantage compared to the half-bridge MMC

Images