Abstract
Modular Multilevel Converter (MMC) has the characteristics of high voltage level and low switching frequency. The traditional modular multilevel converter circulating current control strategy mostly adopts the PI control principle, and the parameter setting is complicated and the accuracy is not high, and the control process is more difficult. Model predictive control strategy is the optimal control method based on the model in the existing time domain. This paper proposes a Model Predictive Control (MPC) method based on carrier phase-shifted pulse width modulation (PSC-PWM) to suppress the circulating current, and output the optimal modulation wave through model prediction. Compared with the traditional control strategy, this strategy is simple to implement, does not require complex tuning calculations, and combines with the traditional capacitor voltage equalization strategy to obtain the output modulation wave. A 7-level MMC simulation control system is built in MATLAB / SIMLINK to verify the theory, comparing with existing control methods, it can be concluded that the proposed method has high calculation efficiency, good control accuracy and strong robustness.
Highlights
Modular multilevel converter (MMC), as a new type of voltage source converter topology[1], can be modularized and has good scalability
The complexity of the control system will be greatly increased[2], The phase to phase circulating current in MMC will directly lead to the current distortion of the bridge arm, aggravate the voltage fluctuation of the sub module and increase the system loss
In [3], the quasi proportional resonance (QPR) controller is improved to suppress the circulating current based on the low pass filter (LPF) circulating current suppression strategy
Summary
Modular multilevel converter (MMC), as a new type of voltage source converter topology[1], can be modularized and has good scalability. The complexity of the control system will be greatly increased[2], The phase to phase circulating current in MMC will directly lead to the current distortion of the bridge arm, aggravate the voltage fluctuation of the sub module and increase the system loss. In [3], the quasi proportional resonance (QPR) controller is improved to suppress the circulating current based on the low pass filter (LPF) circulating current suppression strategy. The model prediction method is used to suppress the circulating current. Because the bridge arm current contains AC and DC information, the bridge arm current is directly controlled to achieve the circulating current suppression effect. The actual current can track the reference current through the MPC prediction and tracking ability, so as to achieve the purpose of suppressing the circulating current. The principle is simple and the operator is simple the circulation suppression can be achieved without complicated setting calculation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
