The Study On Control Of Distributed Grid-connected PV System

In the 21st century, we are confronted with increasingly grave problems like the global shortage of energy, the environmental pollution and the global warming. The solar energy is an ideal alternate with its infinite reserves, universality and clean development and application. China boasts of rich solar energy resources with its reserves reaching 1,700 billion tons standard coal per year in theory, which proves that the solar energy resource enjoys great potential. It is the PV that is the best way of utlizing the solar energy. PV is a dirct generating way which transfers the solar radiation energy into power through PV panels. While a PV system consisting of PV panels, controller and energy storage and etc. can transfer solar energy into usable eletric energy.Grid-connected photovoltaic (PV) generation has become an important part of the research and development in today's energy field. Based on the working principles and output characteristics of PV panels in practice, this paper has discovered and analyzed the misjudgement in the maximum power tracking algorithm through the simulation of some power tracing methods. It also has intensified the stability of the system power tracking, by improving disturbance observation method as an example. Based on the basic principles and operating characteristics of the distributed PV grid inverter, as well as instantaneous power theory, this paper has achieved active and reactive power decoupling control through dq transformations of output load current, making photovoltaic inverter convert acitive component at the maxium power of the solar panels. Meanwhile, with reactive component adjusted by fuzzy adaptive controller, the local load reactive current can be compensated simultaneously and the voltage fluctuation be suppressed effectively. In the related work of this paper, the hardware circuit has been built with the main loop of PV grid inverter and the control strategy has been succefully integrated within TMS320F28335 Digital Signal Processor.