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Modular multilevel converter (MMC) has attracted great attention in the high voltage direct current (HVDC) transmission systems. Redundant submodules (SMs) are usually set to enhance the reliability of MMC. However, if some SMs break down, the arm energy is unbalanced and fundamental fluctuation appears in the DC current. This paper proposes an arm energy rebalancing control scheme to suppress the...
The great number of power modules (PMs) imposes great computational challenge on the voltage balancing of modular multilevel converter (MMC) as the sorting of the PM capacitor voltages is usually adopted. This paper presents a distributed control method for PM capacitor voltage balancing in MMC. With this method, all PMs in one arm are grouped and the sorting algorithm of the voltage balancing in...
This paper presents a H-bridge building block with 1700V SiC MOSFET for a pulsed power application to achieve both high voltage, high current and high switching frequency capability. Both power module level and system level stray inductance is minimized to better utilize the SiC high switching speed capability. Meanwhile, since the large pulsed energy is required to drive the pulsed load, voltage...
This letter focuses on the power module (PM) capacitor voltage balancing of a $\pm 350$ -kV/1000-MW modular multilevel converter (MMC). For this MMC, the current flowing through the IGBTs will exceed the nominal current of the adopted commercial high-voltage (3.3 kV or higher) IGBT products, i.e., 1500 A. As for the PM voltage balancing of this MMC, the switching frequency must be kept low to reduce...
In this paper, a power module capacitor voltage balancing method is presented for a ±350 kV/ 1000 MW modular multilevel converter (MMC) oriented for a back-to-back grid interconnecting project. In this method, a Balancing Adjusting Number (BAN) is proposed to adjust the voltage balancing effect and the switching frequency of the power modules. An accurate switching frequency calculation method is...
Based on modular multilevel converter (MMC) for high voltage direct current (HVDC) system, the startup strategy is researched. The equivalent charging circuits and physical models for uncontrolled and controlled charging process of MMC-HVDC system are derived and the charging current stresses are analyzed. In traditional methods, series resistors in the arm or in the dc lines are used to limit the...
Multiple induction motors (IM) fed by a single inverter are generally applied in traction system, such as rail transportation. The characteristics of the thrust difference are theoretically analyzed firstly. A novel control strategy based on weighted voltage vector is proposed to relieve the thrust difference in each wheel with induction motor. The essence of weighted voltage vector is to select suitable...
According to the dynamic voltage security control, the concept and method of the hybrid control system are introduced, and the dynamic hybrid automatic voltage control (D-HAVC) system is realized. The hybrid hierarchical control system model based on the hybrid theory is set up firstly. In the modelpsilas high layer, the power systempsilas differential-algebraic-equations are linearized, and the eigen-matrixpsilas...
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