Research On The Bundled Capacity For The Wind/PV/Hydro Complementary System

The development of renewable energy such as Wind/PV/Hydro has become the core content of energy transformation and an important way to cope with climate change.In order to give full play to the multi-energy complementary characteristics of Wind/PV/Hydro,it is urgent to do a good job in the planning level of wind and solar bundling capacity design matching the corresponding hydropower stations.At the same time,wind power and PV power are random,intermittent and volatile,and it is easy to cause tremendous impact on the power grid when wind power and PV power are connected to the grid separately.Hydropower has good regulation ability,quick start-stop,flexible operation and strong load tracking ability.As a peak shaving power source,it can better adjust the uncertainty of wind power output,thus promoting the absorption of wind power.At present,how to design a reasonable matching capacity of wind power and PV power according to the different needs of the sending end and receiving end of the system is one of the most important and difficult problems in the multienergy complementary development of Wind/PV/Hydro in the basin.Therefore,the paper analyses the admissible new energy capacity of multi-energy complementary system from the point of view of system operation.Taking Yalong River Basin in Sichuan Province as an example,the capacity planning model of Wind/PV installed capacity allocated reasonably on the basis of existing hydropower stations is constructed.The main research results and conclusions are as follows:(1)The evaluation index system of Wind/PV bundling capacity is constructed.The complementarity,stability and deviation indexes of Wind/PV bundling capacity allocation are defined respectively from three aspects: the complementary characteristics between Wind/PV output,the variation characteristics of Wind/PV combined output itself,and the deviation characteristics between Wind/PV combined output and target load.After that,the ELECTRE method of multi-criteria decision analysis is used to solve the problem.Since the primary task of the Wind/PV capacity ratio is to keep the output as stable as possible,and the matching degree of load is more regulated by the later stage,the optimal wind-light installed capacity ratio near Ertan can be obtained by enlarging the proportion of stability and complementarity in the overall weight.That is,the PV installed capacity accounts for 0.34 of the total installed capacity of wind and light.At this time,the combined output of wind and light is highly complementary,stable and effective for load tracking.(2)Two kinds of Wind/PV bundling capacity allocation models matching existing hydropower stations are constructed.One type of system outputs in the form of stable output,that is,to ensure that the output mode bears the load of the power system.Secondly,gridconnected with the output process required by the power system can bear the waist load and peak load of the power system.In the capacity model based on maximum output,the water volume and flow process play a dominant role,while in the matched capacity model considering grid peak shaving constraints,load and hydropower peak shaving capacity have a higher impact on the results.(3)In the capacity model based on maximum guaranteed output,quantify the change of typical annual total output of different incoming water under the same capacity,and the change of curtailment rate of wind power and surplus water volume with the binding capacity of Wind/PV in different representative years.In the planning stage,the model can provide the maximum guaranteed output of the whole year system with different hydropower representative years and different wind-light binding capacity,and can be used as the decision-making basis for determining the appropriate Wind/PV binding capacity by controlling two different system evaluation indicators,i.e.The curtailment power rate of Wind/PV and the surplus water volume.(4)Based on the research of matching capacity to ensure maximum output throughout the year,considering the operation characteristics of hydropower stations in different periods of the year,as well as the real-time peak shaving requirements of the system,a matching capacity model considering the constraints of grid peak shaving is established.At the same time,the quantitative relationship between the curtailment power rate of Wind/PV,the surplus water amount,the annual total electricity and the annual hydroelectric power generation with the Wind/PV binding capacity is established under different loads.(5)If the Wind/PV/Hydro system bears peak load and shoulder load all year round,the installed capacity of the Wind/PV/Hydro system should not exceed 950,000 kW on the premise of only Ertan Hydropower Station without considering engineering cost accounting;if the system bears base load all year round,the installed capacity of the Wind/PV/Hydro system should not exceed 1.1 million kW under the same conditions.In the actual planning,when the selected wind bundling capacity is large,the total power generation of the system is large,and the overall economic benefit is high;while when the selected wind bundling capacity is small,the curtailment power rate is small,and the utilization rate of the system Wind/PV resources is high.Therefore,based on the analysis of the impact of different indicators on the system,the decision maker can choose a reasonable Wind/PV bundling capacity according to the planning needs.