Modified voltage oriented control resistant to grid voltage disturbances

摘要

Operation of grid connected Voltage Source Converter have to cope with the standards related to preserve of the symmetrical and sinusoidal current with unity power factor even during distorted grid voltage. Hence quality and reliability requirements are challenging because of unpredictable grid conditions such as: variable impedance, interrupts or sudden load changes. For this purpose, it is necessary to develop a current control technique which meets quality requirements, simultaneously providing stable operation under adverse affect of many unfavorable factors coming from grid and power converter construction. Also under distorted grid voltage conditions is difficult to obtain accurately synchronized reference current signal. This paper proposes simple strategy, which provide good performance of Voltage Oriented Control current control technique under strongly distorted grid voltage with robust grid voltage synchronization scheme. The proposed idea involves processed grid voltage and filter capacitor voltage used as feedforward signal. Synchronization scheme is a combination of Synchronous Reference Frame - Phase Locked Loop (SRF-PLL) with Second Order Generalized Integrator - Frequency Locked Loop (SOGI-FLL). Obtained results are explained on theoretical analysis and simulation model.