Uniform Voltage Distribution for Grid-Tied Series Inverters under Unit Failure

Abstract

One of the major challenges of making energy produced by large wind turbine available at consumer level with minimum losses is the power transfer at high voltage. A single unit system with high input voltage requires the use of switches capable to withstand higher voltages stress. These components are not available above a certain voltage range. To overcome this difficulty, DC series connection of n inverters with mature and standard switches is analyzed. Proper operation of such a system must work under a uniform input voltage distribution. Analytical analysis is conducted by the use of the average phase leg technique. The results; obtained by this later technique or by simulation software, show good agreement.Unit failure test is conducted to validate that the input voltage is re-distributed among the n-1 remaining inverters: the continuity of service is accomplished.A tradeoff between efficiency and system performances makes the line resistance a key point of the study. The performances obtained with an acceptable line resistance are unsatisfactory. PID controller parameters are chosen to overcome these shortcomings