An Emergency power supply unit is of great importance to an electric pitch control system especially in MW turbines. Based on a basic parallel-series shift circuit, the paper proposes a novel topology of an emergency power supply unit consisting of ultracapacitors in electric pitch system. Capacitance configuration is obtained and the percentage of efficiency improvement using parallel-series circuit is calculated. Then a control strategy involving three operating modes is established and specific parameters are shown with a flow chart. Finally a simulation of an emergency power supply unit is established and the result confirms the theory.
A PCS Control Strategy for Hybrid ESS with Function of Emergency Power Supply
