Reactive Power Compensation of a Single Phase Grid Connected Photovoltaic System Using Modified PQ Theory and Single Phase Seven Level Inverter

Abstract

This work aims at designing and modeling of a single phase grid connected photovoltaic system with a control strategy that utilizes instantaneous power theory also known as p-q theory. The inverter topology used is the novel single phase seven level inverter. With the use of the multilevel inverter the THD of the load current is reduced to a small value. For the switching pattern of the inverter, hysteresis band current control technique is applied. The MPPT algorithm which is used in this work is the Perturb and Observation algorithm (p&o) algorithm. P&O algorithm is the simplest mppt method. The time complexity of this algorithm is very less but on reaching very close to the MPP it doesn’t stop at the MPP and keeps on perturbing on both the directions. The cost of implementation is less and hence easy to implement.

According to this strategy during sunlight the system sends active power to the grid and at the same time compensates the reactive power of the load. The advantage of this control strategy is that the photovoltaic system is operated the whole day. Furthermore, the p–q theory uses simple algebraic calculations without demanding the use of PLL to synchronize the inverter with the grid. The simulation for the proposed system is carried out using MATLAB simulink software.