Study On Islanding Detection And Control Of Islanded Operation Of PV System

In recent years, with the widespread of photovoltaic power generation, not only to some extent deal with the shortage of traditional energy crisis and air pollution problems, but also to meet the users requirements of power quality and reliability. However, there are many technical problems to be solved, islanding is one of the important topics.Island effect studies mainly divided into the anti-islanding and utilize islanding two cases. However, regardless of the anti-islanding or use of the island, the first task is quick and reliable detection of island. Specific to the advantages and disadvantages of the existing types of islanding detection method, a new Islanding detection method for the PV system is proposed. Which is Based on the fluctuations of this Harmonic voltage, By extracting the higher harmonic components from the wavelet transformation of point of common coupling(PCC) voltage, and then taking its fluctuations as the islanding identification and detection index, which can eliminate non-detection zone(NDZ),without a plus disturbance. Compared with the existing methods, which also can identify the false islanding, such as voltage dips and switching loads.Meanwhile, in order to ensure local load uninterrupted power supply, and improve the quality and reliability of power supply. A new island operation controller is designed, which utilizes an internal oscillator for frequency control and a voltage feedback signal to regulate the island voltage. It is basically a single-input single-output (SISO) system, with limited bandwidth for noise and disturbance rejection, and structural simplicity. Despite uncertainty of load parameter, the proposed controller can guarantee a fast transient response and stable operation of the islanding system.As the development of micro-grid, this paper also built a two-parallel PV system, further verify the effectiveness of the proposed detection method and island operation control strategies. For the theoretical research and engineering application of distributed generation put forward a set of simple, practical and technology-neutral method.