A Model Predictive Direct Power Control Method Based on Three Vectors

Abstract

The invention discloses a model prediction direct power control method based on three vectors. According to the discretization prediction model of the system, the method analyzes the influence of non-zero voltage vector and zero voltage vector on the change rate of active power and reactive power, and predicts different According to the size of the active and reactive power under the voltage vector combination, select the appropriate voltage vector combination and calculate the corresponding action time according to the principle of the smallest power error; through the pulse width modulation technology, drive six switch tubes to operate, so as to control the active and reactive power. Reactive power follows its setpoint. This method does not require AC-side power grid voltage sensors, which saves costs and improves system reliability; uses three voltage vectors in one cycle, which can effectively suppress power fluctuations; compensates active and reactive power to reduce current harmonics Distortion rate; using predictive power control, it can realize active and reactive power without static difference.

Description

technical field [0001] The invention relates to electric transmission technology, in particular to a three-vector-based model prediction direct power control method. Background technique [0002] At present, with the development of power electronics technology and the continuous improvement of the performance of semiconductor switching devices, the three-phase PWM rectifier has developed from uncontrolled rectification to controllable rectification. The PWM rectifier uses fully controlled devices instead of diodes or thyristors, the power factor is adjustable, and energy can flow in both directions, realizing the real "green power conversion". Since the grid side of the PWM rectifier has the characteristics of a controlled source, it can also be used in active power filters, static var generators, unified power flow controllers, superconducting energy storage and other fields, and has great research value. [0003] For the control of the three-phase PWM rectifier, domestic ...

AI Technical Summary

Problems solved by technology

Direct power control adopts the control structure of the voltage outer loop and the power inner loop, and selects the appropriate switch table through the hysteresis comparison of active and reactive power and the position of the grid voltage vector, and then controls the action of the PWM rectifier, so that the active power and reactive power The power follows the given value, but the switching frequency is not fixed, the design of the output filter is more complicated, and only under the condition of a higher sampling frequency can a better control effect be achieved

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