A soc balance control method for cascaded h-bridge energy storage statcom

Abstract

The invention discloses a SOC equalization control method of cascaded H-bridge energy storage STATCOM. Firstly, the chain link current and total capacitor voltage are used as state variables to establish a state equation, and discretize to obtain the discrete state equation of the chain link. Then, combined with the model predictive control based on the finite control set, the required output level Q(k) is obtained; then the SOC value of each module is sorted by the SOC sorting method, and the required output level Q(k) according to the current cycle and At this time, the direction of the chain link current finally distributes the switching action to each H-bridge module, so as to realize the balanced control of the SOC in the chain link. In addition, by averaging the equivalent SOC of each chain link, the command of the SOC balance control of each chain link is obtained, and then closed-loop control is performed to make the equivalent SOC of each phase chain link approach the total equivalent SOC, so as to realize the chain link. SOC balance control between them. The invention solves the SOC balance control problem in the energy storage energy storage STATCOM to a certain extent, and improves the utilization rate and service life of the energy storage system.

Description

technical field [0001] The invention relates to the research field of STATCOM equipment, in particular to a SOC equalization control method of a cascaded H-bridge type energy storage STATCOM. Background technique [0002] When STATCOM is applied to the suppression of commutation failure of HVDC system, it usually requires a large reactive power output. However, STATCOM has the problems that the output voltage and current quality is greatly affected by the capacitance value of the DC side, the reactive power output capacity is greatly affected by the grid voltage fluctuation, and it only compensates for reactive power. The power leads to the unsatisfactory effect of grid voltage stabilization, which greatly limits its application in the field of commutation failure suppression in HVDC systems. [0003] Energy storage batteries have the characteristics of high energy density, small self-discharge, less pollution and long cycle life. In recent years, with the improvement of ba...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a method for SOC balance control of cascaded H-bridge energy storage STATCOM to solve the problem of difficult SOC balance control in STATCOM

Images