A Control Method of Voltage Source Inverter Constructing Rotating Coordinate System for Zero-axis Vector

Abstract

The invention discloses a voltage source inverter control method for constructing a rotation coordinate system for a zero axis vector. In a dq0 synchronous rotation coordinate system, a coordinate system orthogonal to the zero axis is constructed through a 90<0> phase shifting system based on a second-order generalized integrator, the virtual coordinate system is subjected to Park transformation to become the synchronous rotation coordinate system whose rotation surface is vertical to the dq-axis plane, the AC on the original zero axis is then transformed to DC, and zero steady-state error tracking control can be realized through a PI controller. The control scheme of the invention can accurately and quickly track a zero sequence component on the zero axis of the dq0 coordinate system, the scheme has obvious adaptive ability for small-range frequency deviation, and the zero sequence current control effects are excellent.

Description

technical field [0001] The invention belongs to the technical field of power electronic control, and in particular relates to a voltage source inverter control method for constructing a rotating coordinate system for a zero-axis vector. Background technique [0002] Voltage source inverters have been widely researched and applied in the fields of renewable energy grid connection, power quality control, frequency control and speed regulation. In these fields, the control method of the inverter is directly related to the stable, efficient, reliable and optimal operation of the system. The control goal of the voltage source inverter is to make the output current of the inverter track the given current without static difference, and to respond quickly to the changes of various loads. [0003] In practical applications, due to factors such as unbalanced load, nonlinear load, and switch dead zone, low-order harmonics will be introduced into the output current of the voltage sourc...

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Problems solved by technology

[0004] The above commonly used voltage source inverter control methods can track the positive sequence and negative sequence currents without static error, but cannot track the zero sequence current

With the increasing application of three-phase unbalance control devices (SPC) in the field of power quality control, the control of the neutral line zero-sequence current of three-phase four-leg converters has become particularly important, especially in three-phase unbalanced Excessive zero-sequence current under balanced conditions will lead to increased device loss and seriously affect the stable operation of the system

[0005] According to the above analysis, the commonly used voltage source inverter control method uses coordinate transformation to decouple the active and reactive currents, and can track the positive sequence and negative sequence without static error under the positive sequence and negative sequence dual synchronous rotating coordinate system Negative-sequence current, but cannot track the zero-sequence current, let alone suppress the zero-sequence current, which seriously affects the control effect

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