Research On The Power System Of The Photovoltaic Dc Microgrid For Building

Environmental pollution and shortage of resources presents a serious challenge to the development of power system, to deal with this situation, the power industry’s attention on the distributed generation technology has been increasing, the demand for new energy generation is more urgent. DC Micro-grid base on photovoltaic power generation system has the advantages of easy control, high system efficiency and less energy loss and more efficient on use of new energy sources, provides high-quality and high stability DC power for data centers, buildings, homes and other electrical units.From Building Integrated Photovoltaics(BIPV) direction and making full use of environmental resources, this thesis proposes a building photovoltaic power system of a DC micro-grid composed of the east, south and west walls. The system consists of the PV systems on the east, south and west sides of the wall is connected into a unified DC bus, the energy stored in the battery, supply the DC load, it can also go through the inverter, supply the AC load.Aim at the particularity of the proposed PV system, this thesis research on its key technologies. The main work is as follows:1. This thesis analyzes the control methods of this system, points out that there are difficulties exist on the control of voltage control and circulating current for parallel system. Through the analysis, it points out that the easiest and most practical control method for parallel converters is droop control algorithm. According to the characteristics of the parallel system, propose a droop algorithm which does not require the use of interconnection lines, the droop algorithm is achieve by the control of output current feedback voltage droop.2. Use the circuit principle to equivalently simplify the system, so as to analyze the circulating current of parallel DC /DC converters, point out the cause of the circulating current; Base on the analysis, this thesis propose a method for calculating the instantaneous droop coefficient, the control algorithm has good control effect in inhibiting circulating current and load sharing.3. A simulation model of a multi-walls DC micro-grid PV power system is given by the MATLAB/Simulink, the design of each simulation modules is introduced. The system bus voltage and circulating current are simulated respectively to verify the feasibility and correctness of the control algorithm.4. Based on the theoretical analysis, this thesis designed an experimental system, detailed design of each part of the system is analyzed; Experiments are carried out on the established experimental platform, results show that the system is capable of stable operation, which verify the correctness and feasibility of the control strategy of the system.5. A data detection system based on ZigBee is designed for the system. The system uses Arduino controller as the slave computer, uses LABVIEW as the host computer, uses ZigBee to realize the transmission of datas. The data monitoring system is of high reliability, which enhance the operational reliability of the micro-grid system.