Devise On Household Grid-Connected System And Research On Anti-islanding

With the increasingly consumption of the non renewable energy resource whose total amount stored in our earth is limited, human beings is urgent to seek for a green renewable energy due to its awful impact to our environment. Solar energy is accepted commonly because of its particular advantages. However, considering the safety and stability of the grid, one has to take problems of interface with the grid into account, such as power quality, safety protection and so on, all these problems relate to the structure and the control of grid-connected inverter. This paper will concentrate its attention on the household grid-connected system, the topology, grid-connect control strategy and islanding detection methods will be analyzed and studied thoroughly which bases on the special demand of the household grid-connected system.The key technologies for grid-connected system will be expounded thoroughly first, based on special demand of economic expense and high efficiency, half-bridge structure equipped with single inductance to connect the grid will be introduced. To satisfy the grid-connecting criteria of power quality, this paper adopted the double-loop current control with utility voltage feed-forward. Finally, the experimental result will show the feasibility of this control strategy.An efficient anti-islanding strategy must be applied to the grid-connected system. The mechanism of islanding occurring is analyzed and studied in details, and the strategy of anti-islanding will be classified into two types, that is active and reactive methods, whose theories are explained in details. For the further investigating, the common point detecting strategy, active frequency drift (AFD) and automatic phase shift (APS) will be evaluated by the means of NDZ, which leads to the method of practical anti-islanding design. Ascribed to the difficulties of the testing and verifying of the active anti-islanding strategies, a series of methods for experimental testing and verifying will be proposed.Eventually, this paper indicates that mere positive feedback in the anti-islanding strategy is the optimal choice for a balance between power quality and anti-islanding efficiency.