A capacitor voltage balancing control strategy for high-voltage large-capacity VSC-HVDC systems based on tabu search hard optimization algorithm

This paper is written on the valve base control strategy specifically for high-voltage large-capacity modular multi-level converter (MMC) and on the sub-module capacitor voltage balance control strategy using tabu search optimization algorithm. In the context of high-voltage large-capacity VSC-HVDC transmission system, the paper analyzes MMC topology and related valve base control technique. The criteria for sub-module capacitor voltage balance algorithm are brought forward; the switching principle of sub-module pulse distribution is given in-depth study. Based on a distributed system structure, a novel sub-module voltage balance model using tabu search optimization algorithm is presented applicable to VSC-HVDC valve base control technique. In order to set up the objective function and constraints, establish the state decision optimization model, and formulate the optimization algorithm process, this model considers various factors, such as sub-module switch-on/off, energy fluctuations, and key parameters quintuple information tree. Simulation test and off-line test were carried out on the dynamic simulation platform employing PSCAD/EMTDC software. The test results showed that this approach was as good as nearest level approximation in terms of functionality and performance reliability, thus providing theoretical support and engineering basis.