Dynamic response of hybrid energy storage based virtual inertial support in wind application

Abstract

The replacement of conventional synchronous generator (SG) with wind energy conversion system (WECS) greatly reduces the available inertial support in the electrical network. In order to avoid mechanical stress on wind turbine (WT) which is caused by kinetic energy (KE) extraction in providing the virtual inertial support (VIS), this paper proposed an improved technique in converting a hybrid energy storage (HES) into VIS during disturbances for wind turbine systems. The complementary behaviour of supercapacitor (SC) and battery energy storage (BES) offers a great deal of faster and limitless VIS. The trade-off between SC and BES has been achieved through a modified formulation of total available inertial time constant for HES-based VIS. To realize this, the new SC's voltage and BES's voltage are kept updated before being used to form the SC's and BES's reference current in the proposed model. Alongside in operating the HES-based VIS, this paper also introduced a modified energy management system (EMS) by fully utilizing the advantages of the high-power density of SC and the high-energy density of BES in handling disturbances. This modified control technique greatly provides faster and continuous VIS throughout the disturbances compared to the sole energy storage of SC and BES. In addition, based on the tested system of fixed wind speed and variable loads, the proposed HES-based VIS significantly improved the frequency nadir and peak frequency by 3.5 % and 2.7 % respectively. Additionally, the proposed HES-based VIS shows a significant improvement during variable wind speed and load conditions.