Inverters operation in rigid and autonomous grid
Purpose - The aim of this paper is to develop the method of optimal control of the three-phase inverter system for autonomous and power grid operation. The presented method will also allow the cooperation of several inverters creating an autonomous network. This system should also be able to reduce demanded higher harmonics in power voltage according to the list of numbers of these harmonics. In this article the authors describe a system that is used to create a symmetrical three-phase voltage. The supply power is taken from the renewal source. The inverter system as well as cooperation of several such systems to create an autonomous network is under consideration. The generated three-phase voltage should be symmetrical even when the RL load is not symmetrical or else it changes in impulse. Cooperation of the system with the autonomous network is also under consideration. The task is to supply the set current of the basic harmonic to the power grid and possibly to reduce voltage higher harmonics on output terminals of the system. Design/methodology/approach - The method of optimal control for a quadratic objective function was applied. Findings - In the autonomous system the presented method provides a symmetrical three-phase voltage with an unknown unsymmetrical constant or pulsed load. When operating for a power grid the system provides the desired current related to the basic harmonic of the grid voltages. In both cases the demanded higher harmonics of the grid voltages are reduced. Originality/value - Filter of the main harmonic for the power grid voltage was applied. Applied numerical solutions and obtained simulations are also original.
inverter optimal control harmonics filtering vectorial control