Supervisory Predictive Control Of Standalone Wind/Solar Energy Generation Systems

With the sustained and rapid growth of Chinese economy, our energy and environmental crises are aggravating and prominent, environmental protection and new energy technology get more and more attention. Wind and solar energy become the most promising renewable energy sources on account of their exceptional advantages such as zero pollution, no radiation, extensive distribution, endless source and so on. By using the wind and solar resource’s complementary characteristics, Wind-solar complementary generation system can turn intermittent wind and solar power into stable power supply through effective means of transformation, storage and control, thus it becomes the cutting-edge hotspot of research and application in the new energy field.The wind-solar complementary generation system consists of wind power subsystem, photovoltaic power generation subsystem and battery energy storage subsystem. All the parts are designed all alone and run independently, when the wind, light intensity, temperature and load change harmonically with each other, the power system can run under the conditions of stability, economy, security and high quality.For wind power is highly nonlinear, the paper designes a sliding mode controller to response to load change under all conditions. Then, the paper proposes a sliding mode variable structure sub-controller base on the control of maximum power point tracking (MPPT) for photovoltaic cells. It improves the conversion efficiency of photovoltaic cells and decreases the cost of photovoltaic power generation systems. Supervisory predictive controller is designed based on the principle that wind power subsystem has the priority to generate electricity while photovoltaic power generation coordinates with wind power subsystem and battery energy storage subsystem can run to meet the load demand when necessary. The controller can distribute the reasonable given power to subsystems under disturbances such as bad working condition and variable load. That is to say it can not only meets the needs of the load, but also limit the output power fluctuations of each subsystem to protect power system’s equipment. At last, simulation results show the performance of this algorithm.