Research On The Optimal Configuration Method Of Power System Load,Reserve And Maintenance Capacity

At present,China's development has entered a new era.Our country's economy,industry,science and technology are changing rapidly,with increasing energy exploitation and consumption.The fast development of China's comprehensive national strength entails higher and higher demands on the security,stability,efficiency and economy of power systems.Since the beginning of the 21st century,the total installed power capacity of our country has increased year by year.In the 13th five-year plan of electric power development,it is pointed out that while the power industry has seen great achievements,many problems have been exposed in the meantime.For instance,there are serious wasted hydropower resources in Yunnan province and Sichuan province;the peak-shaving capacity of power grids in certain areas is severely inadequate;some power equipment is used inefficiently,and the annual utilization hours of thermal power units are declining year by year.Under the background of further advancing energy conservation and emission reduction,as well as increasingly rigorous constraints of atmospheric environmental protection,it has become a hot research issue to study the theories and methods about optimal configuration of power system load,reserve and maintenance capacity,in order to decrease wasted hydropower and harness fossil energy more efficiently.Based on research in theories and methods about optimal configuration of power system load,reserve and maintenance capacity,this paper focuses on a series of problems about electric power and energy balance,such as power system load distribution,reserve and maintenance capacity allocation,wasting water for peak shaving and so on.With the integrated use of theories and techniques in electric power science,mathematical science,intelligent optimization,system engineering and other fields,research is mainly conducted from such aspects as power load distribution,optimal allocation of reserve as well as maintenance capacity,and pumped-storage power station's operation mode,which includes:(1)The nested-structured load shedding method based on output fluctuations is put forward.Firstly,using the principle of calculating the monthly adjustment coefficient,the idea and method of calculating the typical daily average output of a power station is proposed according to the power system's typical daily average load,monthly average load and power stations' monthly average output in a design level year.Secondly,in accordance with the iterative optimization principle of the improved load shedding method,the working capacity of an individual thermal power station is divided into peak-shaving capacity and non-peak-shaving capacity,for the load distribution calculation based on the constraints of electric power and energy balance.In this way.the typical daily average output and output processes of all hydropower and thermal power stations can be obtained through power and energy balance calculation,given the power system's monthly average load,typical daily load process and each power station's monthly average output.An example is given to verify the advantages and practicability of the proposed algorithm.(2)To address the problem of wasted hydropower for shaving peak load due to bearing the power system's reserve capacity,an optimal model of reserve capacity allocation with the minimum wasted hydropower is developed.Through analysis of the differences in peak-shaving capacity between hydropower and thermal power stations,as well as the correlation between their working capacity and peak-shaving capacity,the optimization direction is worked out based on the principle of equilibrium reserve capacity.The heuristic search algorithm is combined with the accelerative step algorithm to solve the model.Via practical application in a project of optimally allocating power system's reserve capacity,the optimization ability and computational efficiency of the model and the algorithm are proved.(3)The maintenance capacity of power units is incorporated as a variable into the above model to optimize both reserve capacity and maintenance capacity.In the temporal dimension,not only the power balance of the typical daily reserve capacity in every month of the design level year is considered,but also the power balance of each power station's maintenance capacity is taken into account.The correlation between reserve capacity and wasted hydropower of a hydro-thermal power system is deduced to improve the distribution estimation algorithm.Additionally,the generator units' spare capacity is used to modify the initial solution generated by the algorithm,so that the convergence time as well as the possibility of being stuck at local optimal solutions is reduced.The calculation results of an example show that under the constraints of electric power and energy balance,the wasted hydropower is substantially cut down with shorter computation time,which verifies the validity and effectiveness of the model and the algorithm.(4)In view of the hydropower waste in a hydro-thermal and pumped-storage power system,the method of determining pumped-storage power stations' operation schemes with the minimum wasted hydropower is put forth.Given the fact that a pumped-storage power station can account for some of the system's reserve capacity and shift the peak load,according to the system's load level and composition structure in the flood season of the design level year,the typical daily wasted hydropower is exploited by pumped-storage power stations in the way of daily regulation to store energy which is released for shaving peak load,producing their capacity benefits and power benefits to the utmost.The power system's reserve capacity is redistributed,or the load of hydropower and thermal power stations is adjusted to be more stable,so as to increase their peak-shaving capacity or lessen the system load's demand on their peak-shaving capacity,narrowing their gaps between peak and valley load.In the typical day,the system load fluctuate more gently,hence the thermal and hydro power output becomes smoother.As a result,the hydropower waste in the flood season dwindles,which can avoid masses of power loss and enhance the economic benefits of the power system.