Cascade model predictive control method and device for five-level energy storage converter

Abstract

The invention discloses a cascade model prediction control method and device for a five-level energy storage converter. The method comprises the following steps: setting a two-stage model prediction control strategy; respectively controlling a power outer loop of a five-level energy storage converter model and a voltage inner loop of the five-level energy storage converter model based on the first-level model predictive control strategy and the second-level model predictive control strategy; and extracting a harmonic current according to an instantaneous reactive power theory, and modifying the reference voltage amplitude of the five-level energy storage converter model based on the harmonic current, and conducting calculation to obtain a modified voltage reference value output by an energy storage converter model side. A two-stage model predictive control strategy suitable for the topology of the five-level energy storage converter and with a fixed switching frequency is adopted, a virtual synchronous machine strategy based on model predictive control is adopted in the first stage, and the model predictive control strategy with the fixed switching frequency is adopted in the second stage, so that the voltage and the frequency of a power grid can be effectively supported.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a cascaded model predictive control method and device for five-level energy storage converters. Background technique [0002] ANPC five-level energy storage converters are widely used in photovoltaic grid-connected power generation, medium-voltage motor drive and energy storage systems due to their advantages such as low harmonics, low loss, and low voltage stress. [0003] The control strategy of the energy storage converter is the key problem. Existing ANPC five-level modulation strategies are mainly divided into carrier modulation-based PWM strategies (such as phase-shift PWM strategies and level-shift PWM strategies) and space vector PWM strategies. Among them, the carrier modulation strategy has the problem of low DC bus voltage utilization. Although the zero-sequence voltage injection method can effectively solve this problem. However, with the cont...

AI Technical Summary

Problems solved by technology

However, the existing five-level ANPC energy storage converter model predictive control strategy simply considers the adjustment of the midpoint voltage and the suspension capacitor voltage, and does not have the functions of grid voltage support and grid frequency fluctuation suppression.

Images