A mmc circulation control method with a single bridge arm sensor

Abstract

The invention discloses a MMC circulation control method of a bridge arm single sensor, which specifically includes the following steps: (1) sampling the bridge arm resistance-inductance voltage, AC output current and DC bus current, respectively obtaining the bridge arm output voltage and bridge arm current; (2) According to the double-frequency circulating current suppression principle based on the energy analysis of the bridge arm, the number of sub-modules that need to be put into each bridge arm is obtained; (3) According to the output voltage of the bridge arm, the current of the bridge arm and the driving signal of the sub-module at the previous moment, Predict the capacitor voltage of the sub-module at the next time; (4) sort the predicted value of the capacitor voltage, predict the driving signal of the sub-module at the next time and distribute it to the corresponding sub-module. The present invention adopts a single voltage sensor for each bridge arm without detecting the capacitor voltage of each sub-module, saves the cost of the voltage sensor and a part of the current sensor, simplifies the complexity between the hardware circuit and the controller, and enables it to handle 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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