Optimization modelling of HCMC-STATCOMs for offshore wind power based on PSCAD

Abstract

Under normal circumstances, the voltage fluctuation of the wind farm’s grid connection point is mainly caused by the volatility of wind power output. In recent years, with the clustering development of offshore wind power, the voltage fluctuation brought by the output fluctuation of wind power is becoming more and more notable. The main method of improving the reactive voltage problem of wind farms is to add more static and dynamic reactive power compensation devices. Hybrid cascaded multilevel converter STATCOMs (HCMC-STATCOMs) don’t need transformers to increase the device capacity and decrease the harmonics on the output voltage, which is effective in reducing the device cost and volume. This paper firstly introduces the topology and operation principles of an HCMC-STATCOM and then carries out a comparative study on HCMC-STATCOMs and traditional cascaded STATCOMs. Finally PSCAD/EMTDC is applied to model and simulate HCMC-STATCOMs. The simulation result shows that the reactive power of HCMC-STATCOMs can accurately vary according to the system’s demand on reactive power. This means that HCMC-STATCOMs have good dynamic performance and the harmonic contents in the output phase voltage and AC current are quite small. As a dynamic reactive power compensation device, HCMC-STATCOM can be adjusted in real time according to the system’s reactive power requirements, and has the advantages of small volume and low cost. The simulation results show that the properties of HCMC-STATCOMs are advantageous for the operation and control of the system and applicable for the dynamic reactive power configuration of offshore wind power.