Differentiated Power Generation Schedule Considering Environmental Capacity Margin

The impact from a variety of pollution sources including coal-fired power plants on air quality is becoming more and more serious. It is necessary to improve the traditional power system generation schedule methods in order to alleviate air pollution in key areas to a certain extent. Usually the generation schedules of thermal power units considering the minimization of the whole system emissions are often lack of pertinence or even with little effective to alleviate air pollution in key areas. By adjusting the optimization goals of generation schedule and taking full consideration to the difference of environmental capacity margin in different areas and differentiated requirements of environmental improvement goals, this papar explored a new method to plan generation schedule in order to alleviate or improve air pollution in key areas where the environment was monitored through a more scientific and rational behavior of power generation, particularly the behaviors of coal-fired plants.Firstly this paper focused the issues of thermal power units differentiated daily generation schedule. This paper considered the differentiated environmental capacity margin factor in addition on the basis of considering the differentiated thermal power units coal consumption and emission levels. The optimization model of thermal power units’ generation schedule that took the total cost of coal, the total amount of emissions and reduction of the concentration of pollutants contributed to the key areas as the desired objectives was established. The formulation of the desired objective of the reduction of the concentration of pollutants contributed to the key areas was referred to Gaussian puff dispersion model, the predicted weather and the pollution levels in the key areas. For this model, the solving strategy by step and classifying sets to revise the schedules was proposed: solve the basic generation schedule not considering the environmental capacity margin; according to the basic generation schedule and the environmental capacity margins of different areas, divide the thermal power units into the two subsets in one of which power decr eases appropriately and in the other of which an equal mount of power increases appropriately; revise the schedules of two subsets by Lagrange multiplier, resulting in getting a final solution of differentiated daily generation schedule.On the basis of the solution of thermal power units differentiated generation schedule, the paper further discussed the issues of the changes of system spinning reserve and changes of wind power accommodation abilities in different areas from the revision of the basic generation schedule. This paper should focus on solving those issues. When spinning reserve of the regional power grid is lack by the revision of the schedule, it is necessary to revise differentiated generation schedule after the first revision secondly in order to meet the constraints of spinning reserve requirements. When the wind power accommodation abilities of the regional power change by the revision of the schedule, it is necessary to appropriately adjust generation schedule of wind farm.For those two problems to be solved, this paper established the mathematical model of secondary revison generation schedule and sorted and summed 8 scenes after the first revision of the basic generation schedule according to the level of spinning reserve and the utilization of the wind power. For each scene, this paper studied the coordinated approach between the wind power and thermal power generation schedule and designed strategy of the secondary revison. Firstly, get the total amount of adjustment of each regional power of the wind power and thermal power depending on the scene. Secondly, considering the environmental capacity margin factor and the coal consumption levels, allocate the total amount of adjustment to each unit and solve the secondary revison generation schedule by Lagrange multiplier.Finally, for the model and solution of the differentiated generation schedule of thermal power units considering environmental capacity margin and differentiated generation schedule considering impact of wind power and reserve, this paper analyzed two examples which verified the reasonableness of the model and algorithm effectiveness.This research work was supported by National Natural Science Foundation of China Optimal Dispatch of Power Systems for Multiple Expected Objectives with Considering Temporal and Spatial Distribution of API(51377035) and International(Regional) Cooperation and Exchange between the National Natural Science Funds of China and the UK Engineering and Physical Sciences Research Council Intelligent Grid Interfaced Vehicle E-co Charging, i GIVE(NSFC: 51361130153, EPSRC: EP/L001063/1).