Grid-connected Photovoltaic With Power Quality Control System

With the intensifying exploitation of renewable energy in worldwide, solar photovoltaic industry is developing by leaps and bounds. On the basis of renewable energy, the Distributed micro-grid technology, which has been getting more attention in recent years, can improve energy efficiency and maintain high power-supply quality. Grid-connected Photovoltaic system is a hot research point at home and abroad, and it is an important micro-source in the micro-grid with small-scale electricity generation and high permeability, which mainly distributes in the Grid endings. The present thesis, taking the Grid-connected Photovoltaic system with power Quality Control as an object of the study, discusses the double function of active power generation and grid power quality control. In a word, this system both supply energy and improve power quality of micro-grid.Based on the comparison of system structure and operating principal between the micro-grid PV systems and APF, this thesis comes to the conclusion that the micro-grid PV systems and APF have similar topology structure of main circuit, similar mode of operation and similar control method, besides, through unified control the function of APF could be realized by the micro-grid PV systems in theory. GPQC can save the costs of equipping an additional set of active power filter, and makes the new energy power generation more greenearthy and more environment-friendly. This system has certain reference for the power quality control of the distributed grid-connected system in micro-grid with various energy.The basic principle of this system is discussed and the mathematical model is established in this thesis. Focusing on the compound control of active current, reactive current and harmonic current, dead beat compound control is proposed. Active current is required for active energy exporting and DC stability. Reactive and harmonic current is required for compensation. Demand signal computation unifies them to compound instruction. Dead beat compound control warrant the tracking effect rapidly and indifferently. The maximum power point tracking determines the network active current. The calculation of the compound control instruction is accomplished by the instantaneous power theory. On the basis of the above theoretical analysis, the respective design of GPQC is described, including the main circuit parameter design, the hardware design of DSP control system and the software implementation of control algorithms. The simulation and experimental results demonstrate the feasibleness and correctness of the system and its control strategy.