The Relationship Between The New Energy Penetration And The Hydro-plant Efficiency In The Short And Medium Term Coordinated Operation Of Hydro-wind-photovoltaic

As the scale of wind power and photovoltaic power plant development and utilization continues to expand,the high proportion of new energy has become normalized,and its volatility,intermittency and randomness bring great challenges to power grid operation.Hydropower as the ideal peaking power supply has the advantages of rapid start-stop,responsive,strong regulation ability,and hydropower,wind power and photoelectricity between the natural day complementary and seasonal complementary characteristics,water and scenery synergistic operation is to deal with wind,photoelectricity and grid consumption of effective measures.In the new energy generation priority policy,new energy crowded hydropower grid share,changed the hydropower operation,and then also affect the hydropower operation efficiency,that is,new energy accounted for a certain relationship with the efficiency of hydropower units.In terms of natural properties,wind and light resources,as natural resources,are susceptible to weather patterns,especially common weather patterns of several days’ duration;in terms of resource development and utilization,the short time scale operation plan of hydropower system needs to be guided by a longer time scale plan to be more efficient,especially the medium-term plan to guide the short-term plan.In this paper,a study on the synergistic operation of water and scenery at short and medium time scales is carried out to address the impact of weather patterns on the synergistic operation benefits of water and scenery.Taking the upstream Yellow River terrace hydropower station,Republican wind power station and photovoltaic station as the research objects,we first extract the typical scenarios of wind and photovoltaic output under continuous weather patterns,then construct the optimal scheduling model of water and scenery short and medium term nesting,finally analyze the complementary operation law of water and scenery synergistic operation system under different continuous weather patterns,and explore the relationship between the new energy ratio and the efficiency of hydropower units.The main research contents and conclusions of the paper are as follows:(1)For the problem of continuous weather pattern typical scene extraction,a scene reduction method based on the combination of K-means clustering algorithm and simultaneous backgeneration reduction algorithm is used to extract continuous weather pattern typical scenes,and the elbow rule and contour coefficient are used to determine the optimal number of clusters for the K-means clustering algorithm synthetically.The research results show that the adopted method can effectively select the typical scenes of wind and photoelectric output under different continuous weather patterns.(2)A short-and medium-term nested model for cooperative operation of water and scenery is constructed.The medium-term scheduling model provides the scheduling end-of-period water level for the short-term model to control the operating boundary of the short-term model;the short-term model takes the previous day’s scheduling end-ofperiod water level as the starting level for the next day and updates it on a rolling basis during the scheduling cycle.The medium-term optimal scheduling model uses genetic algorithm to solve the model with the objective function of minimizing the deviation of total power generation and load of the water scenery,while the short-term optimal scheduling model uses stepwise optimization algorithm to solve the model with the objective of maximizing power generation.The research results show that the shortterm and medium-term nested water and scenery cooperative operation optimization scheduling method,on the one hand,takes into account the change trend of wind power and photovoltaic output in the range of consecutive days,on the other hand,improves the effect of cooperative operation by controlling the short-term and short-term rolling update in the medium term.(3)The trend of changes in the efficiency of hydropower units under different new energy ratios is analyzed,and the research results show that the power generation efficiency of hydropower units increases as the new energy ratio decreases under a given load condition when water and scenery operate together.The new energy ratio has an impact on the inlet and outlet flow,power output and water level change during the operation of the reservoir.The increase in the proportion of new energy in the waterlandscape complementary system squeezes out the hydropower load to varying degrees,resulting in the reduction of hydropower output,which in turn affects the generation efficiency of hydropower units.(4)The impact of different continuous weather patterns on the relationship between the new energy share and the efficiency of hydropower units was analyzed,and the results showed that the average unit efficiency in three continuous weather patterns from high to low: weather pattern 2 > weather pattern 1 > weather pattern 3.The sensitivity of Huanghe five-stage power station to the change of unit efficiency due to new energy ratio in different weather patterns is: Jishixia > Gongboxia > Lijiaxia >Laxiwa > Longyangxia.The degree of influence of weather patterns on unit efficiency is: weather pattern Ⅲ> weather pattern Ⅰ> weather pattern Ⅱ.