A converter module unit, converter, direct current transmission system and control method

Abstract

The invention discloses a converter module unit. The anode of the first switch module is connected to the anode of the first energy storage element, the cathode of the second switch module is connected to the cathode of the first energy storage element; the cathode of the diode is connected to the first switch module. Anode, the anode of the diode is respectively connected to the cathode of the second energy storage element and the cathode of the fourth switch module, the anode of the fourth switch module is connected to the cathode of the third switch module, and the anode of the second energy storage element is connected to the anode of the third switch module ; The positive pole of the third switch module is connected to the positive pole of the fifth switch module, and the negative pole of the fifth switch module is connected to the negative pole of the second switch module. This structure can provide good DC-side fault ride-through performance, overcome the limitations and deficiencies of structures such as full-bridge modules and clamping dual modules, and have better performance in terms of economy and technology. The invention also discloses a control method of the inverter module unit. The invention also discloses a converter, a direct current transmission system and a control method.

Description

technical field [0001] The invention belongs to the field of flexible DC power transmission, and in particular relates to a converter module unit, a modular multilevel converter based on the converter module unit, a DC power transmission system, and the aforementioned converter module unit, modular multilevel converter A level converter and a control method for a direct current transmission system. Background technique [0002] The core of the flexible DC transmission system is the voltage source converter based on fully controlled devices. Multi-level technology is the optimal solution for realizing high-voltage and large-capacity voltage source converters. Compared with the two-level converter, the multi-level converter can use low-voltage devices to achieve high-voltage level output without direct series connection of switching devices. In recent years, the emergence of Modular Multilevel Converter (MMC) has enabled the successful application of MMC in the field of flex...

AI Technical Summary

Problems solved by technology

[0006] The clamp dual module is composed of two traditional half-bridge modules cascaded through a full-control switch and two clamp diodes. Compared with the full-bridge module, the number of full-control switches is effectively reduced and the operating loss is reduced. Problems: First, when the clamping dual module is in the state of all full-control switches locked, due to the asymmetric structure of the diode in the topology, the equivalent capacitance of each bridge arm is inconsistent when starting AC charging, and the capacitor voltage The rise rate is inconsistent, which makes the consistency of the high-potential energy acquisition and monitoring of the entire converter poor, which is likely to cause system misjudgment; second, when the DC fault occurs, the two DC support capacitors of the clamping dual module are connected in parallel to the AC Between the system voltage and the fault point, the DC voltage of the module rises slowly, and the dynamic response time for clearing the fault is longer

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