Answer Happy

Consider an isolated AC microgrid system shown below. The microgrid system contains conventional DEG, PV panel, Wind turbine Generator (WTG), Fuel Cell (FC) system, battery energy storage system (BESS), and flywheel energy storage system (FESS). As shown in Fig. below, the DGs are connected to the microgrid by power electronic interfaces which are used for synchronization in AC sources like DEG and WTG and to reverse voltage in DC sources like PV panel, FC, and energy storage devices. The FC contains three fuel blocks, an inverter for converting DC to AC voltage and an interconnection device (IC). The FC has a third order model. Each microsource has a circuit breaker to disconnect from the network to avoid the impacts of severe disturbances through the microgrid or for maintenance purposes. Nominal values of the DG units, as well as loads are given in Table below. A specific amount of power produced by the DEG is considered as spinning reserve for secondary frequency control. A simplified frequency response model of the system with the parameters values of the block diagram are given below. The main system parameters are D (damping coefficient), H (inertia constant), R (droop constant), T+(turbine time constant). Iz(gene rator time constant), TFESS(FESS time constant), and TBESS (BESS time constant). Using MATLAB/SIMULINK determine the following: a. Study the system stability. b. Analyze the system (without PI controller) frequency behavior Af due to a 50% step load change APload c. Design a suitable secondary PI controller or any other controller to limit the system frequency performance to a maximum overshoot of 5%, maximum settling time of 1 sec and zero steady state error. d. Show the final frequency variation response compared with the uncontrolled one.