A method to estimate speed droop ratios for primary frequency control responses in power generation units

Abstract

Primary frequency control (PFC) in power generation units is very important for power grids to suppress frequency fluctuations and preserve load-generation balance. The speed droop ratio is the most crucial performance index for a PFC response. This paper proposes a method to estimate speed droop ratios from historical data for PFC responses of power generation units. The proposed method is composed by three steps. The first step selects data segments containing PFC responses through a hidden Markov model describing underlying frequency states. The second step obtains piece-wise linear representations (PLRs) of the generated power and power grid frequency in the selected PFC data segments. The third step formulates different PFC response stages based on the PLRs, from which speed droop ratios are calculated. Numerical and industrial examples are provided to support the proposed method and compare with two existing ones.