A control method for phase-to-phase power balance of power electronic transformers

Abstract

The invention relates to an interphase power balancing control method of a power electronic transformer. The interphase power balancing control method comprises the following steps of calculating a d-axis component and a q-axis component of a zero sequence voltage according to an active power difference value required to be output from arbitrary two of three phases of the transformer under the effect of the zero sequence voltage and active power required to be output from the third phase in the three phases under the effect of the zero sequence voltage; calculating the zero sequence voltage according to the d-axis component of the zero sequence voltage, the q-axis component of the zero sequence voltage and angular frequency of a power grid; separately superposing three phase modulation waves output from a high-voltage stage of the transformer with the zero sequence voltage to generate new three phase modulation waves; and generating corresponding trigger pulses to control the high-voltage stage of the transformer according to the three phase modulation waves so as to achieve interphase power balancing control. By the method, balanced correction can be carried out on three phase transmission powers of the power electronic transformer (PET) when an unbalanced fault occurs in the voltage of the power grid, and the interphase power balance of the PET and the DC voltage balance of the high-voltage stage are ensured when the unbalanced fault occurs in the voltage of the power grid.

Description

technical field [0001] The invention relates to a power electronic transformer phase-to-phase power balance control method, which belongs to the field of power electronic device control. Background technique [0002] Power Electronic Transformer (PET) can not only realize the functions of traditional transformers such as voltage conversion, electrical isolation and bidirectional flow of energy, but also has the advantages of small size, light weight, constant output voltage amplitude, and reactive power compensation. , with the rapid development of high-power semiconductor devices and magnetic materials, it has become the key equipment for smart grid construction. [0003] The topology of the main circuit of a power electronic transformer is as follows: figure 1 As shown, it consists of high voltage stage, isolation stage and low voltage stage. The high-voltage stage is an H-bridge chain structure. Each phase in the high-voltage stage is composed of several sub-modules cas...

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Problems solved by technology

[0012] The purpose of the present invention is to provide a power electronic transformer phase-to-phase power balance control method to solve the problem of unbalanced PET three-phase transmission power when the power grid voltage unbalanced fault occurs

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