NEW ALGORITHMS FOR STABILITY OF OUTPUT VOLTAGES OF STAND-ALONE SINGLE STAGE FIVE LEVELS INVERTER IN SOUTH ALGERIA PV SYSTEM

摘要

This paper proposes two new control algorithms of three phase single-stage stand-alone five levels inverter for PV power supply system. The objective of these strategies is to get a symmetric and stable output voltage inverter. The first regulator compares the root mean square of output voltage in the same time to its previous and to its reference values and calculates the new modulation index to be applied. The second regulator uses the PV and load currents, the capacitors voltages and the output vector of SVPWM to choose the redundancy to be applied to get equal input capacitors voltages. To reduce the size of control algorithm, vectors groups composed each one by six vectors are constituted. Also, a new redundancy selection choice criterion is applied to balance the input capacitors DC voltages reducing the derivation cases from 24 to only 6. This proposed algorithm takes into account the variations of the photovoltaic array voltage and load currents. A real data of global horizontal irradiance and ambient temperature profiles of Ghardaia city (south of Algeria) are used to validate the performances of proposed control techniques.