Modular multilevel converter bridge arm current direction measuring device and judging method

Abstract

The invention relates to a modularization multi-level current converter bridge arm current direction measuring device and a judgment method. The modularization multi-level current converter bridge arm current direction measuring device comprises a first single chip microcomputer U1, a second single chip microcomputer U2, a first current sensor TA1, a second current sensor TA2, a first operational amplifier U3, a second operational amplifier U4, a first photoelectric coupler U5, a second photoelectric coupler U6, resistors R1-R16, a capacitor C1 and a capacitor C2. The modularization multi-level current converter bridge arm current direction measuring device has the advantages that the bridge arm current direction is indirectly judged by detecting the current situation of an internal switching tube of a submodule according to the switching tube conduction state, and the requirement for the insulating degree of the current sensors can be greatly reduced; meanwhile, power supplies of the sensors can be isolating power supplies of a submodule drive protection circuit, and a circuit does not need to be additionally arranged; the complex degree and cost of the modularization multi-level current converter bridge arm current direction measuring device can be greatly reduced according to the characteristics, and reliability can be improved.

Description

technical field [0001] The invention belongs to the technical field of power electronics and relates to a device for measuring the current direction of a bridge arm of a modular multilevel converter and a judging method. Background technique [0002] The continuous development of power electronics technology provides strong support for the construction of intelligent, clean and efficient modern power systems, and has been widely used in the fields of high voltage direct current transmission (HVDC) and flexible alternating current transmission (FACTS). Modular Multilevel Converter (MMC), as a new generation of high-voltage and high-power converters, has large power transmission capacity, independent control of active and reactive power, AC output without complex filtering devices, high reliability, and high reliability. It has many advantages, such as power transmission to passive or weak receiving end systems, and is considered as a representative technology of flexible DC t...

AI Technical Summary

Problems solved by technology

In addition to the fundamental wave component, the bridge arm current also contains a DC component and a frequency multiplier component, which cannot be accurately measured by an electromagnetic current transformer. The existing measurement method is to measure the bridge arm current through a current sensor, and then directly judge the current direction

Although this judgment method itself is simple and direct, the disadvantage of this measurement method is that the measurement point is on the connecting line of the bridge arm, and the insulation level of the current sensor and its isolated power supply is very high. The insulation level is the same as that of the AC side of the device, that is, it generally reaches tens to hundreds of kV levels

This makes the development or selection of high-voltage current sensors difficult, greatly increases the complexity and cost of the current direction detection device, and also reduces the reliability

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