Operating point stability analysis of SMIB power system equipped with high PV penetration

This paper presents the operating point stability analysis of a Single Machine Infinite Bus (SMIB) power system equipped with high Photovoltaic (PV) penetration. The detailed dynamical model of the synchronous generator in dq reference frame is considered including the dynamics of the damper windings and Automatic Voltage Regulator (AVR). A DC-DC buck-boost switch mode converter is placed as an intermediate stage between the PV array and the inverter. The main function of this implementation is to inject the voltage corresponding to the PV generator Maximum Power Point (MPP) by automatic adjusting its duty cycle. The PV array is designed to provide a maximum output power of about 0.78 pu at the full solar irradiance. The nonlinearity of the output characteristics of the PV generator is taken into account. Operating point stability analysis is performed by extracting the eigenvalues of the linearized model around the operating point at different solar irradiances. System response after successive step changes on the synchronous generator input mechanical power at three solar irradiances based on the complete nonlinear dynamical model is investigated. For given synchronous generator input parameters, the response of the system after successive step changes on the solar intensity is addressed. It is found that high PV penetration via DC-DC buck-boost converter and DC-AC inverter is practically possible, experiences a stable operating point and can withstand successive step changes on system parameters in case of practical solar irradiance levels. All numerical simulations are conducted using MATLAB software package by building the code required.