| Abstract |
With the increasing penetration of renewable energy systems into the power grid, stability and safe operation during grid faults have become a great challenge. The phase and frequency of the grid voltage are the important information for the acquisition of the reference value of the grid-connected converter control signal and ensure the smooth, reliable and stable operation of the grid-connected converter system. In this paper, a new concept the frequency locked loop with frozen mechanism is proposed, which is used for solving the grid synchronization problem of the power grid under unbalanced and distorted operating conditions. The frequency locked loop with frozen mechanism consists of the frequency-locked loop (FLL) based on the Second-order generalized integrator (SOGI) which tuned at grid frequency and the frequency frozen mechanism which guarantee the stability during the severe faults. |
