Active Power Control of Grid Connected SPV Plant Based Microgrid Using Active Power Regulating Scheme

Abstract

In remote areas the cost of transmission of electrical power to the load from the main grid is very huge which increases the per unit cost of electricity. Moreover the regular damage to the transmission lines due to the natural phenomenon's affects the power supply. In addition to this the malfunctioning of the grid can also affect the power supply. Hence, in such cases our local generating stations can be utilised for meeting up the local demand. The use of local generating stations in unison with main grid forms a microgrid which increase the reliability and ensure continuity of the supply. In this work operation of the solar photovoltaic (SPV) system based 200kWp microgrid operated in grid linked mode has been analysed. The active power of system is regulated by an active power regulating strategy. For the analysis, the system has been modelled in MATLAB/Simulink. The system comprised of two SPV plants connected to a grid and the capacity of each SPV plant is 100kWp. The perturbation and observation based MPPT algorithm has been used for maximal power tracking from the SPV plants. In the control scheme voltage from grid and current from the inverter are transformed to dq0 coordinates and active (P) and reactive (Q) power are enumerated. The calculated P & Q are compared to Preference and Qreference, respectively. The transformed voltages and currents are also added. After this PWM generator generates the triggering pulses for inverter switches. The control strategy operates in two control loops, an outer power control loop and inner current control loop. A PLL is also used to match the phase and frequency of inverter output with the grid voltages. The obtained results shows the tracking of the peak power from the SPV for every value of irradiance and temperature inputs. The results also show that by using the control strategy the active power fed to grid can be properly controlled and can be changed to any reference value.