A Method For Formulating Monthly Energy-trade Scheduling Considering Multiple Energy Sources

The output power of renewable energy sources,whose proportion of capacity is constantly increasing,is highly uncertain,which brings many problems to the formulation of monthly energy-trade scheduling.The existing threshold value of the annual base electricity deviation rate to ensure fairness is an empirical value,and there is no solid theoretical basis.With the gradual increase of the scale of monthly energy-trade scheduling,and the increase of the proportion of new energy,the security and fairness of the scheduling have become the key considerations,which need new theories and methods to support.In the formulation of monthly energy-trade scheduling with high proportion of clean energy,the annual plan implementation progress and daily operation security constraints are focused on,the essence of monthly energy-trade scheduling is essentially a planning problem of "combination of details,macro and micro".The time-sequence simulation method can set up constraints from both macro and micro perspectives,by applying this method to the scheduling,the new and traditional energy coupling and collaborative optimization could be realized.According to the idea,the monthly energy-trade scheduling model can not only consider the fair distribution of annual contract electricity,but also take into account many security operation constraints in daily dispatching,and can also be easily solved by CPLEX software.The widely used deviation rate threshold method has the problems of relying on empirical values and lacking of fairness level corresponding standards.The Gini coefficient method is used as an indicator to measure the fairness of power progress,which can be set as a constraint in the monthly energy-trade scheduling model.Because the Gini coefficient method has a recognized and mature fairness level corresponding standard,it can make up for the shortcomings of the deviation rate threshold method.The monthly energy-trade scheduling model based on the time series simulation method is extremely computationally intensive and difficult to converge.Based on the physical characteristics of new energy prediction accuracy decay with time,the paper proposes a new four-stage modeling idea " modeling by stages,the model of former stage is relatively accurate,and the model of later stage is relatively rough",the accuracy of the stage's model gradually decreases with time,this idea can significantly reduce the calculation workload.The results of the example show that the proposed method can comprehensively consider the coordinated generation of multiple energy sources to reduce the impact of renewable energy fluctuations;lots of constraints such as security operation and system safety on short time scale can significantly improve the security of the scheduling;the Gini coefficient constraint ensures the balance of the power generation entity's power execution progress and the fairness of the scheduling;the four-stage modeling idea can effectively reduce the amount of calculation for solving the model,guarantying the convergence of the model,and make sure the model conform to the decline characteristics of the forecast accuracy of the renewable energy,so that the method could have good general practicability for large-scale systems.The proposed method has good feasibility and practicability,and can provide a new idea for the dispatching department when formulating the monthly energy-trade scheduling.