Optimal Digital Load Frequency Control of Smart Grid Considering Sampling and Time Delay Based on Warm-Up Gray Wolf Algorithm

Smart grids usually apply digital load frequency controller to regulate the frequency via the wide-area communication network, where the data sampling and transmission delay of the signal transmission may degrade the frequency control performance. Plus, the inherent nonlinearity of frequency regulate may weaken the control performance. In this paper, a digital PID-type load frequency control (LFC) scheme based on warm up gray wolf optimization algorithm is designed for large-scale renewable energy grid-connected smart grids, considering the influence of data sampling, transmission delay and nonlinearity. First, a new digital PID-type LFC model considering data sampling, transmission delay and nonlinearity is established. Second, a novel warm-up gray wolf optimization method is proposed to optimize the parameters of the digital PID controller. The method can fully consider the nonlinearity of LFC and the influence of time delay and sampling, and the PID parameters with optimal control performance can be derived by taking the control performance as the objective function. Finally, simulation tests are undertaken on the three areas LFC systems. The simulation results illustrate the effectiveness and superiority of the proposed LFC scheme, and the necessity of control scheme design to consider the data sampling, transmission delay and nonlinearity.