Research On Limiting Capacity Calculation Of Grid-connected Photovoltaic Power Station Based On Robust Optimization

With the rapid development of society and economy,traditional fossil energy consumption brings not only environmental problems,but also predicament of energy shortage.Faced with such severe situation,photovoltaic power generation has become a most potential one among new energy power generations by virtue of its abundant resource and environmentally-friendliness.Affected by natural factors,solar radiation is obviously fluctuating,so the photovoltaic power output is uncertain.With the growing number of large photovoltaic power station,the uncertainty of its power output certainly impacts on system stability when operating in-grid.Therefore,the capacity limit research which synthetically considers the fluctuation of photovoltaic power output and power system constraint is of significance.It is an important research content of system planning and operation,and can provide preference for construction of large grid-connected photovoltaic power station.This paper presents the development and research status of photovoltaic power generation and the development and application of robust optimization theory.By comprehensive analysis and contrast of different modeling methods to deal with uncertainty,this paper introduces robust linear optimization which needs not to obtain the uncertain parameter's probability distributions.Robust optimization method based on cassette and ellipsoid set and random variable distributional robust optimization method are expounded.In general mathematic model of the capacity limit of grid-connected photovoltaic power station,solar radiation is taken as a random variable.According to different ways to deal with random variable,the capacity limit of grid-connected photovoltaic power station is studied by cassette robust optimization and random variable distributional robust optimization,and corresponding robust optimization models are built.The former one depicts disturbance of solar radiation by cassette uncertainty,further describe the uncertainty of photovoltaic power output.While the latter one describes by combining upper-lower limits and the expectation of solar radiation.The model is transformed to certain linear programming problems via duality theory and solved.In allusion to the capacity limit of grid-connected photovoltaic power station based on the two different robust optimization methods,simulation calculation and analysis on a 46-bus system.Results indicate that it is quite essential to consider the uncertainty of photovoltaic power output,and the uncertainty has obvious effect on the in-grid capacity limit.Capacity limit of photovoltaic power station varies under the effect of factors such as the grid-connected bus,solar radiation disturbance range and different values of the constraint variables.Contrasted to cassette robust optimization,random variable distributional robust optimization method can provide flexible calculation results between optimization and robustness.Thereby the practicality and effectiveness of the model are proved.