MMC (Modular Multilevel Converter) ring current control method of bridge-arm single sensor

Abstract

The invention discloses an MMC ring current control method of a bridge-arm single sensor. The method comprises the following steps that (1) the resistance-inductive voltage, AC output current and DC bus current of bridge arms are collected, and the bridge-arm output voltage and the bridge-arm current are obtained; (2) according to a frequency doubled ring current inhibition principle based on energy analysis of the bridge arm, the number of sub-modules needed by each bridge arm is obtained; (3) according to the bridge-arm output voltage, the bridge-arm current and a sub-module driving signal of the last moment, capacitance-voltages of the sub-models in the next moment is predicted; and (4) the capacitance-voltage predicted values are ordered to predict a sub-module driving signal of the next moment, and the sub-module driving signal of the next moment is distributed to corresponding sub-modules. A single voltage sensor is used for the bridge arms, it is not required to detect the capacitance-voltage of each sub-module, the cost of voltage sensors and part of current sensors can be omitted, the complexity of a hardware circuit and a controller is reduced, and the method can be used to process a large-scale MMC system.

Description

technical field [0001] The patent of the present invention relates to a MMC circulation control method with a bridge arm single sensor. Background technique [0002] With the significant increase in the voltage level and power level of power electronic switching devices, High Voltage Direct Current (HVDC) used in high-power applications has attracted extensive attention from industry and academia, and has developed rapidly at home and abroad. Compared with conventional multilevel voltage source converters, modular multilevel converters (ModularMultilevel Converter, MMC) have the advantages of high modularity, easy expansion and less harmonic content in output waveforms, and structurally replace multi-winding The transformer reduces the volume of the device and saves costs. At the same time, the modular system structure also brings convenience to the redundant design of the system. The contradiction between device level and high-voltage grid system level has greatly promoted...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is that, aiming at the high-voltage passive inverter system with modular multi-level structure, it provides a method of circulating current control based on the single sensor of the bridge arm, which solves the problem of multi-voltage current sensor in the modular system. At the same time, the double-frequency circulation of the bridge arm is suppressed, and the power loss is reduced. On the premise of the stability of the control system, the balance of the capacitor voltage of each sub-module in the high-voltage modular multi-level passive inverter system is ensured, and the device is realized. Efficient use of energy and saving of manufacturing costs

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