Research On Grid Integration Of High-Penetration Renewable Energy

To realize energy revolution,it is of great necessity to develop the high proportion of wind and solar power.However,in the actual power grid operation,the curtailment of wind and solar power remains common.Therefore,improving accommodation of wind and solar power has become an important research direction in the future.Currently,insufficient peak-shaving capacity is the main reason for the wind and solar power curtailment.In view of the power source structure of China,performing the flexibility reformation concerning thermal units is still the preferred choice for realizing the high proportion of renewable energy consumption.In addition,considering the nature complementarity characteristics of wind farms and photovoltaic stations,coordinate operation of these two resources not only can promote the consumption of renewable energy,but also can strengthen the market competitiveness of these two resources.Based on the above-mentioned research direction,further research is conducted in this thesis.The main work is presented as follows:1)An optimal flexibility reformation planning model of thermal units based on interval optimization is presented,and the operation optimization of the full scenario is realized in the form of intervals.In terms of economy,the generation cost of thermal power units significantly increases during the deep peak regulation stage,causing large fluctuations in the unit generation cost in each scenario.In response to this phenomenon,the model optimizes the operation cost of multiple scenarios by the full-scenario optimization method,which can thus provide a scheme with better comprehensive economy.In terms of power flow adaptability,considering that the power grid requiring flexibility reformation usually has high penetration of wind power,the model uses the full-scenario optimization method to accommodate the power flow uncertainties,thus providing a scheme with better power flow adaptability.In dealing with the proposed model,two steps including the group search optimizer with multiple producers and the multiple attributed decision-making method,are used to ensure that the obtained scheme with the best comprehensive economy can best satisfy the users’ requirements.2)A unit commitment interval optimization model for deep peak regulation is proposed.Considering that the power grid requiring thermal power units for deep peak regulation has higher wind power penetration,which can increase the fluctuation range of node power.Therefore,an affine-arithmetic algorithm is adopted in the optimization process to reduce the boundary of power flow calculation,thus guaranteeing that the obtained optimal unit commitment scheduling can meet all the fluctuating requirements in the system.Additionally,for the increasing power generation cost of the thermal unit in the deep peak regulation stage,the proposed model selects the operation cost interval as the optimization objective,and the average and deviation of the objective interval are also extracted as the sub-objective,thus realizing coordinated optimization and further ensuring the the obtained optimal unit commitment scheduling is comprehensively economic.3)An optimal wind/solar/storage coordinated operation model is proposed,which can accommodate for the large-scale power system.In this model,an optimal coordinated bidding strategy is proposed,also presenting a revenue distribution method.In the coordinated bidding strategy,this model utilizes pumped storage stations to adjust the coordinated output power based on the complementary characteristics of wind and solar power.As a result,the ancillary service cost in the form of firm power supply can be reduced.Furthermore,the multi-period firm power supply mode is adopted to accommodate different connected ratios of wind farms and photovoltaic stations.In the revenue distribution method,the individual operational characteristics of each participating member are considered,and various revenues and costs are allocated according to these characteristics.Thus,it can reasonably allocate coordinated bidding revenues and costs among the participating members.