Balancing the active power between the generation side and the demand side to maintain the frequency is one of the main challenging problems of integrating the increased intermittent wind power to the smart grid. Although the energy storage system, such as battery energy storage system (BESS), has potential to solve this problem, the installation of the BESS with large capacity is limited by its high cost. This chapter investigates the frequency regulation of the smart grid working in the isolated mode with wind farms by introducing not only the BESS but also dynamic demand control (DDC) via controllable loads and the plug-in electric vehicles (PEVs) with vehicle-to-grid (V2G) service. First, modelling of a single-area load frequency control (LFC) system is obtained, which includes the wind farms equipped with variable-speed wind turbines, the simplified BESS, the air conditioner based DDC and the distributed PEVs. The LFC system contains traditional primary and supplementary control loops and three additional control loops of the BESS, the PEVs and the DDC, respectively. Then, state-space models of the closed-loop LFC scheme with/without communication delays in the control loops are derived, and the stability of the closed-loop system with time delays is investigated via the Lyapunov functional based method. Third, gains of proportional integral derivative (PID)-type controllers are tuned based on the H∞ performance analysis and the particle swarm optimization searching algorithm. Case studies are carried out for the single-area smart power grid through the MATLAB®/Simulink platform. Both the theoretical analysis and the simulation studies demonstrate the contribution of the DDC, the BESS, and the PEVs to frequency regulation, and the robustness of the designed PID-type LFC against the disturbances caused by the load changes and the intermittent wind power and the delays arising in the control loops via theoretical analysis and the simulation studies.
Frequency regulation of smart grid via dynamic demand control and battery energy storage system, Page 1 of 2
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