Research On Key Technologies For Peak Load Shaving By Public Buildings' Air Conditioning Loads

With the gradually widely usage of the air conditioning(AC)loads in our country,the peak load of urban power grid has swiftly increased in summer over the past decade.In the city,the public building's AC loads which take up a large proportion of the total power network load in summer are easy to control centrally.Therefore,it is of great significance to improve power grid load characteristic in summer and realize safe,stable and economic operation of power grid by excavating peak shaving potential of large-scale air conditioning loads and adopting reasonable regulation patterns for peak load reduction of air conditioning loads.This dissertation focuses on the study of public buildings' AC loads which participate in the day-ahead peak load reduction in summer.The main contents of the dissertation are as follows.Firstly,the characteristics of baseline load curves and the typical scenes for peak load shaving of public building's AC systems are analyzed of typical industry types in summer.Also,the short-term load forecasting method for public building's AC system is studied.Next,the operating characteristics and the suitable control modes of public building's AC loads of different types are analyzed.Also,the modeling methods and the specific control strategies of public building's AC loads of different types are studied.The equivalent thermal parameters(ETP)model of public building's central air conditioning(CAC)load is emphatically established.A fine and flexible load reduction control strategy of public building's CAC load is proposed.Furthermore,based on the proposed multiple-rank control patterns of public building's CAC system,a combinatorial regulation model of large-scale public buildings' CAC loads for jointly participating in the peak load reduction is set up,also,a day-ahead power dispatching model with extensive participation of CAC loads is built.Finally,a coordinated control strategy for distribution network is proposed which is suitable for the scene of large-scale load reduction of public buildings'AC systems.The specific research contents carried out in the dissertation are as follows:1.The characteristics of the daily load curves of public building's AC systems are respectively detailed analyzed of three industry types of shopping mall,office building and guest house in summer.Then,the typical scenes in which the public building's AC loads participate in the peak load reduction are respectively summarized.The meteorological factors which influence the power consumption of public building's AC system are analyzed.Moreover,considering the accumulation effect of the meteorological parameters,a short term baseline load forecasting method of public building's AC system is proposed.2.The operating principles and characteristics of decentralized AC system,cool storage CAC(CSCAC)system and non-cool storage CAC(NCSCAC)system are respectively elaborated.Also,the applicable occasions and suitable control modes of public building's AC loads of different types are respectively summarized.Then,the operating characteristics and efficient operating power ranges of both screw-type and centrifugal chiller units are emphatically analyzed.They provide the bases for the specific implementation of load reduction control strategy of public building's CAC system.Next,the modeling method of decentralized AC system is introduced.On the other hand,taking the building,equipment and meteorological parameters into consideration,the ETP model of public building's CAC system is established.Furthermore,the load reduction control strategies and their effects are detailed studied of different types of public building's AC system.A load reduction control strategy for public building's CAC system by alternatingly and periodically opening and closing the terminal equipment of each floor is proposed.The operating efficiency of CAC system and the human comfort requirement are both considered in the control strategy.3.Taking the operating efficiency of chiller unit of CAC system into consideration,the schedulable capacity of one public building's CAC system is calculated.In order to facilitate the unified control of large-scale public buildings,AC loads,multiple-rank control patterns for both NCSCAC and CSCAC load are proposed.On the basis of load reduction control strategy and multiple-rank control pattern,a combinatorial regulation model of large-scale public buildings' CAC loads for jointly participating in the peak load reduction is set up.The model aims at minimizing the grid regulation difficulty and the operating efficiency of CAC system,also the energy utilization efficiency and the human comfort requirement are all considered in the model.The simulated results verify the effect of the regulation model on the regional power grid load reduction.Furthermore,combining with the model of traditional generating unit,a day-ahead power dispatching model with extensive participation of CAC loads is established.The target of the model is to achieve the minimization of the system operation costs.A case study on a region in Nanjing is presented to verify the peak load reduction effect and the economy of the model.4.The model of distribution network is established,which is with the joint participation of large-scale public buildings' controllable AC loads.The modeling method of the public building's controllable AC load is emphatically analyzed.By applying the virtual synchronous motor control to the rectifier of distribution network model innovatively,a novel coordinated control strategy for distribution network is proposed which is applicable to the scene that large-scale public buildings' AC loads participate in the peak load regulation.The control strategy aims at stabilizing the frequency and voltage of distribution network.Based on the coordinated control strategy,the equivalent model of the DC distribution system is established in the form of 'the prime mover-the generator-the variable load'.The large-scale public building' AC loads will have effects on the voltage and frequency of the distribution network when responding to the instruction of peak load reduction.The simulated results show that the effects can be restrained by adopting the coordinated control strategy.