Battery Energy Storage Systems for Improving the Performance of Wind Farms. A Study at Hitachi Energy.

The increasing penetration of wind power in the Nordic power system leads to a reduction in the share of conventional synchronous generation, which traditionally provides key ancillary services such as voltage support and black start capability. This thesis investigates how Battery Energy Storage Systems (BESS), provided by Hitachi Energy, can enhance the performance of wind farms by providing these services. The study is based on dynamic simulations using DIgSILENT PowerFactory and PSCAD. In PowerFactory, scenarios with different degrees of synchronous generator replacement are analyzed to investigate the impact on voltage response of the system, and how BESS integration influences the system's transient response during a short circuit disturbance. The PSCAD simulations focus on the BESS's capability to provide voltage and frequency support in grid following mode, and to perform black start in grid forming mode. Results show that BESS can improve voltage recovery and oscillation damping under fault conditions, and accurately track power setpoints during normal operation. The black start scenario demonstrates the ability of BESS to energize an islanded grid. While economic aspects and synchronization challenges are not modeled, the findings offer technical information on the role of BESS in supporting renewable integration.